THE CRYSTAL STRUCTIIRF: 3

DETERMINATION

by

Cashman R.S .Me Hanpton

B. Sc., University of Victoria, 1967

A THESIS SUBMITTED I N PARTIAL F W I W N T OF

THE RlQUIREbfENTS FOR THE DEGREE OF

MASTER OF SCIEXCE

i n the Department

SIMON FRASER UXTVERSITY

June, 1970

APPROVAL

Title of Thesis: The crystal structure determination of [ ~ h ( f 6 f ~ ~ ) ] [ci~-Rh(~o)~~l~]

2

S t$r Supervisor (F.W.B. s in stein) +'

Examining Committee ( J . M. D1 ~ u r i a )

Date Approved: July 27, 1970

iii J ABSTGCT

The crystal structure of di (l,2-bis (diphenylphosphino )hexa-

f luorocyclopentene ) rhodium(1) cis-dicarbonyl-dichloro rhodate (I ), I

[~h(f 6f~~)2] [ois-~h(C0)$1~] has been determined from three-dimensional

x-ray data collected by counter methods. Using full-matrix least-

squares techniques, the structure was refined to a conventional R factor

of 8.8% for the 1628 observed reflections. The salt crystallizes in

4 1 n - . - I 1- l3-- -2 -LA D----? - --JA- u r r u v ~ u * ~~~~~~r upobv €;A vuy r+l/ a. K UA F ~ A ~ U C I AVI UIILLQ ~ ~ 1 1 ~ 3 i i i 6 1;i3E ~f

dimensions a = 17.722(1); and c = 36.773(4)i the calculated density is

1.59~/cd. The density as measured by flotation was between 1.60 and

~.63~/c11?. Both of the chemically and crystallographically distinct rhodium

atom environments possess crystallographic two-fold symmetry, In the

case of each rhodium atom, the arrangement of coordinating atoms is

approximately square planar. The two Rh-P distances are 2.282(6$ and

2.300(6)i and the bite of the chelating ditertiary phosphine, fgfos,

as measured by the intra-ligand P-P distance is 3.I.l1(8)k

TABLE O F CONTENTS I

T I T L E : P A G E ~ ~ ~ e ~ . ~ e e ~ e ~ ~ ~ e ~ e ~ a ~ ~ ~ * ~ * ~

EXAhENING COMMITTEE APPROVAL . . . . . . A B S T E l A C T . . e . . e . . . e . . e * * . , m e . * * e * e * *

. . . . . . . . . . . . . . . . . . . . . . T A B L E O F C O N T E N T S

L I S T O F T A B ~ e e ~ e ~ e ~ ' ~ ~ ~ ~ ~ ~ ~ ~ e ~ e ~ ~ ~ ~ e e

L I S T O F F I G U R E S ~ ~ ~ ~ ~ ~ e ~ e ~ ~ e ~ ~ ~ * e e ~ e e ~ .

. . . . . . . . . . . . . . . . . ACKNoWZ;E ;?X;MENT. . . . . . .

INTRODUCTION. . . . . . . . . a * . . . . . . . . . . . . . .

m E R I ~ A L . . . . . . . . . . . . . . . . . . . . . . . . .

STRUCTURE SOLUTION . . . . . . . . . . . . . . . . . . . . . . DISCUSSION

. . . . DIUENSIONS FROM PREXESSION PHOTO WASURETaNTS

B, DESCRIPTION O F COWUTER PROGRAld3USED I N T H I S VORK . , . . . . . . . C. PREPARATION O F P2S5Br4 AND h 'a2N2O2~5H20

D. DESCRIPTION OF WEIGHTING SCHEME USED I N T H I S WORK . .

PAGE i

i

iii

V I I .

LIST OF TABLES I

J

V

PAGE

. . . . . . Measured and calculated structure factors 6 I

Final positional and thermal parameters with

. . . . . . . . . . . . . . . . standard deviations 12

Equations of best planes and distances of atom

from planes . . . . . . . . . . . . . . . . . . . . . 25

Inter-atomic distances and bond angles with

. . . . . . . . . . . . . . . . . standard deviations 28

Root-mean-square radial thermal displacements of

. . . . . . . atoms with isotropic thermal parameters 33

. . . . . . . . . . . . . Anisotropic motion analysis 3 5

Correlation coefficients (6 ) greater than 0.45 between

parameters of the carbonyl atoms . . . . . . . . . . 36

FIGURE

1.

2.

3

4 *

5

6 .

v i

LIST OF FIGURES

PA03

The crystal structure of [~h(f~fos)~] [c~s-R~(co)~c~~] 18 1

View down a two-fold axis . . . . . . . . . . . . . 19

T h a m l ellipsoid plot of the cation [~h(f~fos)~]+ J

22

Diagram featuring ring conformations of the cation 23

Alternative structural proposals for f6fos~e(CO)g . 37

Two possible isomers of f6fosFe(CO) 3 * . * . O e . 39

vii

I am gra tefu l t o Dr. F.W.B. Einstein f o r h i s guidance and

assis tance i n t h i s work.

I would a lso l i k e t o thank Dr. W.R. Cullen f o r providing the

c rys t a l s of [Fth(f6fos [R~(co)$~ .

As part of an investigation of transition metal compounds containing

fluorocarbon-bridged ditertiary phosphines and arsines as ligands (2,13,14,

32-35), reactions between these ligands and chlorodicarbonyl rhodium dimer

were studied. The intention was to prepare neutral complexes of the type,

(diphosphine)~h(C~)Cl, which are products of symmetric cleavage of

[R~-I(CO)~C~] 2, and these products were to be examined to ascertain their 7

ability to undergo oxidative addition.

It has been found 2 however, that the ligands ffos and f6fos do

n = 2: ffos

n = 3: f6fos

not cleave R~(cO)~C~ symmetrically as does the saturated hydrocarbon-

bridged diphosphine, 1,2-bisdiphenylphosphinoethane. Rather, the cleavage

is unsymmetric as with the reaction of [R~(co)~c~]~ Kith the unsaturated

hydrocarbon-bridged aipnospnine, i,2-bisdipnenyip~osphinoethyiene, and . -

yields salts containing cations of the type [~h(diphosphine)~]+.

As well as confirming that the reaction between f6fos and chlorodi-

carbonyl rhodium dimer occurs via unsymmetric cleavage of the dimer,

this work reveals certain features (see page 38) of the cation which have

implications for work on other compounds containing the f6fos ligand.

The crystal structure of [~h(f~fos )2] [C~S-R~(CO)~C~~] described in

this thesis was determined by the techniques of single crystal x-ray

diffraction. These techniques and the instruments used are very commonly

used in x-ray crystal structure determinations and will not be described

here*; instead, the emphasis is on a critical analysis of results.

* One good book describing the practical side of a crystal structure determination is Stout and ~ensen(1).

Crystals were kindly provided by Dr. W.R. Cullen and their

preparation is described elsewhere (2). The sample received was a

mixture of two different kinds of crystals. The majority were small

needles (of the order of 0.1 mm.) and the smaller fraction were crystals

of the type whose structure determination is described here.

Crystal Data: [Rh(f6fos )?] [cis-Rh(~~)~~l~], formula weight 1421.20,

is tetragonal, space group 14~/a (identified unambiguously from Laue

group 4/m and systematic absences). a = b = 17.722(1)i, c = 36.773(4)1,

V = 11,815d, 1.60s Dmc1.63g/cc. (as measured by flotation*), z = 8,

-1 Dx = 1. 5Yg/cc. , F (000 ) = 5664 and r (h-K 4) = 8.2 cm. . X-ray Data Collection: Weissenberg photographs of the zones h01, hll,

h21, h3l and h41 using Cr-K* radiation, together with precession

photographs of the zones hkO and h01 using Mo-Kd radiation, showed

absences for hkl with h+k+l= odd missing, for 001 with 1 = f+n+2

missing and for hkO with h = odd missing.

All counter data were collected using a crystaL mounted along its

"bt' axis. The crystal was in the shape of a slightly tetragonally

distorted octahedron. Distension was in the ttc" direction of the crystal,

so that from apex to apex in that direction the distance would be about

+ 0.21(- 0.01 mm. ) were one of the apices not chipped off. In the ltblt apical

Wrystals separated from the crystal mixture by hand and slightly smaller than that used for counter data collection were found to sink very slowly in CCl4(p = 1. 6og/cc. ) and to float just beneath the surface in concentrated aqueous KI solution ( P = 1.63~/cc., maximum density for concentrated aqueous KI solution).

5

(not-distended) direction, the dimension of the crystal was about

O.l&n~n. Cell dimensions were determined by least-squares +%in

high-angle reflections measured on a Picker four-circle autclnated I 0

diffractometer (A= 0,70926A, unfiltered Mo-K, radiation was used to

obtain cell dimensions at 19O~), The errors were estimated f r o m

the internal consistency obtained,

Reflection intensities f,or the unique set of data were zeasured

using a Picker four-circle diffractometer equipped with our own semi-

automation, Zirconium filtered hlo-K,radiation was measure2 by a

scintillation detector with pulse-height analysis, The take-off

angle was l.1•‹ and a symmetrical 0 -28 scan of 1.6* width was used.

Background was measured by stationary counts lasting 12 secozds on

either side of the 1.6~ scans. m e stationary counts were sxbtracted

from the scanned intensity for each reflection. Any net int.ensity

which was less than two standard deviations (ie,, 26; a = fl, and M is

the sum of counts obtained for the scan plus two background counts)

was coded as unobserved. Unobserveds are denoted by a minus sign in

the Fobs columns in Table I, Of the 2934 intensities recorded in

the range 0 < 28<!+0, 1628 were observed, Three measurements for each

of two standard reflections were taken at intervals ranging ,Orom 15

to 5 hours, The average of these six measurements changed about

55% during the data collection,

Because of the large size of the unit cell care had to te

exercised in order to recognize cases of scans overlapping =re than

Table 1. Measured ~ n d calculated s t ructure fac tors

I 0 1 1 1 -.,, , 6 a,. -8.. 9 0 ,a, -,,, v * . I -,. . . , I 0 .I,.

I, 0 I", ... ,I . 10, - 8 " . b * 0 .,, ... a , r , , . , I , , .a ., 4 I ,, ..I . t - 8 , m . 1 1 1 . 11.

1. , I , . ,I, I, 1 .. .. 1. I . , . I, 8 . , - 9 , .,

1 4 11. ., 1 1 1 1 1 . 111 I , - 1 , .I, # , .,. - 8 . . , I.. (4,

I 1 I I.. I*,

O 1"" -1.) 0 ,,I -In. 0 ,I. .I.. 0 I., -JOY 0 I , . .I,, . d B * 7,s. 0 ,.. .,,, 0 111 -11. 1 I.. .I., , *,. . U D I a". - w e , .. -*. , ,Q, .,a. , a , , -,*a I I., .I". I 9. .., , -,. .,I 1 1 . 4 130 t 1 1 1 a,. a 1 1 e 19. 1 11. ,*" a 1.. I t , I 2.. , I . ' , ,, ,<" a I* .. 1 1 1 1 , I $ l , lS *a, I 1 1 1 ,.r s 11, ,.. , 2.8 '.+ 1 I t . 2.. I 1 % ) 1%" , 6, 1, , -,. $1 . a,. st,. . I,. -I,, . .H -..a . 1+1 -21, . 101 -2,. . 111 -11. . I , . -,"I . $7 - , I , I11 -2.. . I., -I.. , .. 7 -.,. . .., -.,, 3 82. -2,. . -3. -., , I. -.. , 1.1 -62, 6 I" to* . .,. 1.1 . .I" .I, . ,.I I , . . 103 101 . 3 0 . 100 ,I. . 11) 111 I I.. 101 I 1.1 **. 1 11. 1.1 1 *a, 5,) 1 11: 1 r - 8 . . 7 -9. A,,

1 127 111 . ,up -1,. I 1,. -2.. . I.. ->.. 8 a,, -,J? I .o - , ,a * .I -.O I , I0 -,a. * 111 -11, . t.4 -,3, . M -,. . ,,a -t.o . .. -1. . 11, -1.1

t,. -,,, to I , , I.. 10 to. 111 10 .1 ,a, t o ,st 1.1 I 0 I.. t1. 10 I,, , I . , I ,,, 8.3 I, t,. I,. 11 -,1 8 . I , 10 r . I , m. ,a. 11 1.1 1.9 I 1 I . 1 5 ,a >., -2.0 11 -1. -1, , I - 3 , - I I, I.. -0,. I, 1.1 -I#. t 1 1 1 1 -191 I, $6. .,., I, ." -*. 0 , I,. - t o 11 -1. -3, I, I,. -I,. I. . I ,, ,. 0 , $5 1. 11. 111 ,. 1 1 1 111 1. 10. 111 1, .I 8 . I. U .I 1. 11. 11, I. I. -., ,. ,.a -,,,

e 2.3 ,u 0 I* I.. 0 7 ' -I, 0 ,,a -*. 0 95 ., 0 ,I\ 1.4 4 -.* .I 0 -,. 2, L 2.6 -2.9 I I , , -2,. , ., 3, , ,.. L,. I 1, -9. , 1.2 - 1 1 1 1 11 -1J3 1 .1 -. , 2%. -,a* , ,7 . , I I tII I M I ,I ., 2 -,. .." 1 1.) - , I s 1 W -)I z -,I . , 20. I.. , .e - 1 8 , 3 -,. -1. * . I 8 , 3 70 .O 3 n qr I I 0 9 11. , . , I -2. . 42 9, . -1, -11 . I ,O 61% . .. I. . - 3 , .. . -,, $0 . .* ., . .,, ., . 70 .. . , I t 1 0 , ,.P - , r . , 1,. -I,, 5 -7 - w I 1, ... . -,, , I 9 -,. .,, . ., -.. 6 I." -1,. . ,,, - a , % . 1 1 1 -11, . - 9 , -,, . -,, ,. . .I* I ? P ,Oh - a . I 61 ., 1 1 . 1 , 1 0 I I.. 1.1 , -,, .a 1 . I \ -,, , -,& .,, , .I ,I a .I, I , 0 ,.a 110 . L , . I . . . * % .a . .I\ ..I . -,. - 8 % * .I I , " ,, -10

,I, .I., " .,, .,* . .I. - 9 , . .,I - 1 1 . - 9 . -,. .,. .,, 111 1 1 , - 8 . 8 t o - 8 . -,, 10 1. .. ,a .,. -., $ 0 6 % . - 4 2 , ,O 11. - a , , 11 1.. 1.0 ,, .,. ., ,, .?, .,a I, - 8 . n ,I I". I", I, l t . 69.. 1, .. !. 1, . I . 8. I , -I. -,I 6, . , t .,. 1, -,. .. I * .. -1 . I , .,. .., I , -,* 1 s 8 , .,, -,. 4 , ,. .#. 6. -,. ...

. , .. .. P , . I , . . , - , a ,

t , - r 8 , b - 9 . .,. , I I .I. I. ,' . . I . .(.

a . ." . .. .,. . . - 3 , .." 0 . -,: .,,

I" . 1. .. 8: . . ,. , ~ 3

I. . -,. .,, 8 3 -,. ,% b , .," .,* . . I. .. . . 4- .., . I .I , ' A

,I 3 .I. I , I I - , . . I . ,, . ". .. i . 3.L -4.. . . 101 - 1 % ) . . . , I 1 . . " I I,. ," . - 3 . -.

,I . -,. -.. 1. . .,I .. , . - 2 . -3

3 7 - w -,, , 7 -,. 8 , , , - 9 . ?, 1 . ,. :I ,, 7 - 3 . .. ,, , -1. -,. 0 . -,, ,- I a - 3 , t. . I a. 3 , . . - 3 s , a , -,, -*.

I C . - 3 % - 3 6 11 I - , , I' , 9 - u - 4 , , a -,, 3. . , $ 3 0

I . -,, 'I 9 . Li -..I ,, -,. , P 0 ,o -*. -1, z ,I ,L .. . 1, -,. b, . , . , - 9 . a . L O - 3 . -..

10 1, - 3 . . 11 ,t ,, - 9 . <*

L ,I - I \ I. S I t - 3 6 . 9 ,I - 9 , ,I 7 L L - 7 . 9,

1 1 -1. - 1 $ 1 11 -1. -1. " , I -,. , , 6, - I + - 3 . . I, - 3 , - I . ,r -,, ,r e ,, - 3 . .? ,: t, -,+ - 2 , 1 1 ) -1 . - 1 % , I , -9, . , L, - w I . 7 1, - 3 . -, J 1. -., -10 , 1. - 9 . -., . L. -,7 ' 7 . 1. -1. 2, , ,, - 3 . -20 1 1. -,. 2 1

Table I. Measured and ce.lculated structure factors (continued ) :

.......I r..

I S 1.9 Z H I 0 I t . I,, 3 0 115 ID, . 0 .I 5. . e ,,. to,

11 . , ,I 11. I S 0 I. 1D. 0 1 1.0 I% I 1 1.1 111 . 1 11. 12,

t -3, ,. . . . . . . 10 I 8.0 I.. 11 1 131 1.0 I I ,a, -,,. I 1 I.. -1,. s t I , , -I*. ? , 10) -11, . I 1.8 -,lo

I , I I" - 8 , D I I , . -,r. 1 I ,.a -,,I 6 , ,., -,a, 6 I ,** -,,a , 1 1 1 1 -11.

11) * 101 -11, Ll , .. -,.

I . I,? ,I. * . 1.. I . , % . 8.6 a,. I . , I . 6,.

8

one ref lect ion, and some e f fo r t was made t o correct f o r t h i s

e f fec t . It appeared tha t no serious e r rors of t h i s type remained, I

since there were no large deviations of Fo from Fcalc a t the end of

the refinement t o enable detection of such an ef fec t . This e f fec t

was observed par t icu lar ly along the c* axis and a t low values of 28

(length of c = twice the length of a ) .

Lorentz and polarization fac tors were applied and s t ructure

fac tors calculated in the usual way. No correction f o r absorption

was made since the small s i ze and the shape of the c rys t a l suggested

tha t t h i s correction would be small. Furthermore, the var iat ion

of in t ens i ty due t o absorption was calculated t o be no more than

5% (with an estimated e r ro r i n t h i s percentage of 22% due t o uncertainty

i n the c rys t a l s i ze measurements).

STRUCTURE SOLUTION

10

F'rom the unsharpened Patterson function it was possible to assign

approximate positions on the two-fold axis to two crystallogrs$xically I

distinct rhodium atoms, and also to one other atom which was te.nporarily

assumed to be a chlorine atom. One cycle of least-squares on four

atoms including the three above as well as one misplaced chloene

atom yielded a conventional R factor of 46.2%. These two rhocuas

later proved to be the rhodiurfis of the cation and anion. The =csmainder

of the structure was filled in as prominent features of successive

difference maps and good chemical sense dictated.

With all the non-hydrogen atoms allowed appropriate coorcEnates

and isotropic thermal parameters, the structure was refined to a

conventional R factor of 11.5% (weighted R, 12%). It was inferred

from prominent features of a difference map at this point that the

fluorine atoms were vibrating a~sotropically. After two cycles of

least-squares, varying anisotropic parameters for the fluorinez,

the R factor dropped to 9.e (weighted R, 10.l% ) . Prominent features of a difference map at this stage pointed to the possibility tkat

the anion was vibrating anisotropically. The R factor after two

cycles of least-squares varying anisotropic parameters for th+ anion

had dropped to 9.4% (weighted R, 9.7%).

Up to this point all observed reflections had received wLt

weights. Unobserveds were not included in the least-squares rsfine-

ment (ie., they were effectively given zero weight). After refLne-

ment involving weights which were the reciprocals of the varizzces

The R f ac to r dropped t o i t s f i n a l value of 8.8% (weighted R,

10.5%) a f t e r four changes had been made : ( i )anomalous dispersion

corrections (3) were applied t o the rhodium scat ter ing fac tor curve;

( i i ) t h e cationic rhodium atom was allowed t o "go anisotropicw;

(iii )the phosphorus scat ter ing f ac to r curve was employed, i n the

calculations, f o r phosphorus atoms which had been mistakenly given

chlorine sca t te r ing power; and ( iv) the carbon ( ~ ( 6 ) ) a t the extreme

end of the fluorocarbon moiety of the f6fos ligand was allowed t o go

anisotropic. It seemed there was a suggestion of anisotropy f o r t h i s

carbon i n the difference map a t t h a t stage. The value f o r R of 8.8%

signif ied a reasonable point a t which t o discontinue the refinement

fo r a large problem which involved a la rge amount of computing time.

I n the l a s t cycle of least-squares refinement all ele~ents of the ftd-l-

matrix were varied except f o r the atomic parameter$*of atoms C(16)-~(21).

These parameters were varied i n the previous cycle. Final posi t ional and

thermal parameters a re l i s t e d i n Table 11. 0

A f i n a l difference Fourier contained no peaks la rger than 0.86 e/$,

which corresponds t o about 79% of the height of the broad peak tha t was found

f o r the carbonyl group. A peak of 0.86 e/i3 was found about 2.36 away

from the anionic rhodium atom.

There was a l so a peak of subs tant ia l height remaining i n the 0

f i n a l difference map about l.49A from the cationic carbon atom fa r thes t

from the rhodium of the cation. It i s i n a posit ion roughly

corresponding t o the posit ion a f luorine atom would be expected t o

*The weighting scheme used i s described i n appendix D.

Table 11. Final posi t ional and thermal parameters with standard deviations,

Atoms with isotropic thermal parameters: I

Atom x P

m H e r e d throughout t h i s thesis , standard deviations a re indicated by brackets. For example, f o r 3,23(l4), the standard deviation is 0.u.

* The posit ional coordinates x,y and z a re f rac t ions of the uni t c e l l edges a ,b and c respectively.

u Atoms with anisotropic thermal parameters (continued) :

Atom x Y z 1

take for another conformation of the fluorocyclopentenyl I ring.

This together with the unreasonable anisotropic motion of the fluoro- I

carbon fluorine atoms led us to consider the possibility of disorder

involving another conformation of the fluorocyclopentenyl ring. Such

a conformation, if it exists, would probably occur less frequently in

the crystal structure than the one which was refined. However, no

- o f i n ~ m ~ n t . i n v o l v i n ~ two conformations of the ring was carried out as - ----------- -

such further investigation would have required an unwarranted amount

of computer time.

The function minMsed was v( \Fol - IFc i )2 and the discrepancy

Scattering factors used were those tabulated in "International

Tables for X-ray ~rystallography'~ (4 ) .

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DISCUSSION

A. Crystal Structure

The c r y s t a l s t ruc ture of [ ~ h (f6fos )2 ] [ c i s - R h ( ~ ~ ) ~ ~ l ~ ] contains

[ ~ h ( f ~ f o s ) 2 ] + i o n s and [ c i s - ~ h ( ~ ~ ) ~ ~ l ~ ] - i o n s packed together i n a body-cen-

t red te t ragonal l a t t i c e (see f igure 1 ) . The asymmetric un i t contains ha l f

a cation and ha l f an anion. A l l rhodium atoms a r e on two-fold spec i a l posi-

t i ons so t h a t both cat ion and anion possess crystallographic two-fold symme-

t ry . The d ispos i t ion of coordinating atoms about t h e rhodium i n both ca t ion

and anion i s appraximat,elp square planar. Cat-ion and sninr! I r e sc pocked te-

gether t h a t t h e chlorines of t he anion a r e directed toward the adjacent cat-

ion, a s i l l u s t r a t e d in f igure 2. The chlorine atoms of the anion, which a re 0

separated from the cat ionic rhodium by a dis tance of 5 .23(1)~ , a r e d i rec ted

away from the ~ ( 3 ) and ~ ( 3 ) * atoms and towards the P(4) and ~ ( 4 ) t atoms.

This i s a.ccommodated by a twist i n t h e cat ion such t h a t the P(4) and P(4)t

atoms a re depressed r e l a t i v e t o t he anion above them apparently in favour

of the anion chlor ine atoms#. Consequently the cation is not superposable

on i t s mirror image; t h i s means there a r e two d i s t i n c t enantiomorphs* i n . -

the c rys t a l l a t t i c e , re la ted t o each o ther by e i t h e r a centre of symmetry

o r a g l ide plane operation.

The anion a l so has adopted a twist in the form of a te t rahedra l d i s tor -

t ion . The oxygen atoms of t h e carbonyl groups a r e 0.32(3)8 on e i t h e r s ide

of the plane of the rhodium and two chlorine atoms.

B. The Anion

Substant ia t ing the presence of the [ c i s - ~ h ( ~ ~ ) ~ ~ l ~ l ' a n i o n i s the i r

* A t l e a s t , t h e r e a r e two predominant enantiomorphs; there may be disorder involving o the r conformations.

spectrum(2) whose two carbonyl stretching frequencies closely resembled the

carbonyl stretching frequencies of other compounds containing this same anion

I Though the presence of this anion is certain, not all the atomic parame- i

ters are certain. The C-0 bond distance (0.91(3)i) is too short to believe 8

since C-0 distances are usually 1.1A (7-10,lY). Furthermore, in two other

cases (11,20) where carbonyl groups are trans to chlorine atoms in rhodium

complexes, the C-0 distances are 1.181 (average value) and 1.098(13)X. Thus

to the extent that the C-0 bond distance is not feasible, the atomic coordin-

ates for the carbon and oxygen are in question. That these coordinates are

questionable is also indicated by the high correlation coefficients between

them.* Between the x-coordinate of the carbon atom and the z-coordinate of I,

the oxygen atom the correlation coefficient is 0.54 and between the z-coordin-

ate of the carbon atom and the x-coordinate of the oxygen atom the correlation

coefficient is 0.52(see Table vII). No other correlation coefficient between

positional parameters of different atoms is greater than 0.30. A possible

reason for these high correlation coefficients for the carbon and oxygen is

mentioned on page 34. However, the Rh-C-0 angle is reasonable: 177(6): and

linear within experimental error,

The Rh-C1 distance corrected for thermal motion is 2.35(1)i# which 0

is similar to values obtained (2.36~ (average value) , and

*A correlation coefficient shows the interdependence of parameters in the refinement. It is defined for the parameters i and j as 6 =be . / * b T i r where bij is the ijth element of the inverse matrix of the ij 1 J 3 J

least-squares procedure. 0

#2.31(1)~ was the value for the Rh-C1 distance before correction for thermal motion.

f igure 3 . Thermal ellipsoid p lo t of the cat ion (~h(f~fos)~] '

24

2.372(3)X) for othor rhodium complexes where a chlorine atom is

trans to a carbonyl group (11,20).

6. The Cation +

The cation [Rh (f6fos )2] (figure 3 ) contains two crystallographically

identical f6fos ligands. The bite of the ligand as measured by the

intra-ligand P-P distance is 3.111(8)i.

Each half of the c a t i o n cont,ains twn p i c k s r e d , fjv~-memhF,y~d

rings. Carbon atoms C(14) and ~(15) are respectively 0.28(2)i

and 0.26(2); out of the plane of the phosphorus atoms of the same

ligand and the rhodium (~h(1)) atom. The fluorocarbon ring is also

significantly puckered. This can be seen by examination of the

results in Table I11 for the weighted mean plane through four of the

carbon atoms of this ring. ~(6), the carbon atom farthest from the

cationic rhodium atom, is significantly out of this plane

,- \ ? \ (in fact by O.iO(j)A). Featured in figure 4 are the conformations of

- -

the five-membered rings of the cation; the cyclopentenyl ring

conformation is shown to be consistent with the orientation of the

C-F bonds farthest from the rhodium atom. ~ ( 5 ) is in the axial

position, ~ ( 7 ) in the equatorial.

This latter consistency does not preclude the existence of another

conformation of the fluorocyclopentenyl ring. Rather it

underlines that if there is another conformation existing, it is

a less preferred one. Indeed, one feature of these C-F bonds lends

support to the proposal of another conformation in which ~ ( 5 )

Table 111. Equations of best planes and distances of atoms from planes.

Anion: (1) Plane containing ~ h ( 2 ) and i t s bonded C 1 atoms

Atom distance from plane ( in i)

Cation: (2) Mean plane through ~ h ( l ) and i t s bonded P atoms

- z + 5.193 = 0

Atom distance from plane ( i n i) ~h(l) 0.008(2)

P(3 0.008(6)

P ( 3 p O,OOR(h] - -

P(4) -0.104(6)

~ ( 4 ) ' -0.104 (6 )

(3) Plane containing Rh(1) and only the P atoms of one l igand

0 .0355~ - 0 .0321~ - 0,99892 + 5.6055 = 0

Atom distance from plane ( i n i) ~ ( 1 4 ) 0.28(2)

c(15) 0.26(2)

Table 111. (continued) I

Note: The equations are given i n ff coordinates. Planes (2) and (4) a r e weighted mean planes. The weight assigned t o an atom i s inversely proportional t o the sum of the standard deviations for the posi t ional coordinates of the atom.

27

becomes equatorial and F(7) becomes axial: namely their lengths.

The ~(6)-~(5) bond length (see Table IV) is ostensibly rather long

while the ~(6)-~(7) bond length is ostensibly rather short. A

range of 1.32-1.36i for C-F bond lengths in a similar ligand (21)

suggests the average value 1.33i is a reasonable one for a C-F bond

in this situation.) Such lengthening and shortening is to be expected

4 C + -a.w- he-- - i= s E~uxz~x~g cct cf (6 ! s l ~ c + _ ~ ~ ~ P E ~ ~ + _ T I d 9 1 ~ .I --- to the wc(6)" of another "flipped" conformation. If the

~ ( 6 ) - ~ ( 5 ) bond is of the order of 0.11 too long the actual position

of the ~(6) atom would be of the order of 0.2 6 out of the plane of the other four fluorocyclopentenyl carbon atoms. This would place

0

the ~(6) atoms a distance of the order of 0.4A apart, which is close

to the value of the root-mean-square thermal displacement of the ~(6)

atom along the ~(6)-~(5) bond (0.34(4); ). Thus the apparent

irregularity of C(6 j-~(5,7j bond lengths is actually in keeping with - -

the presence of the other conformation.

D, The Thermal Motion

Thermal parameters as obtained from the refinement procedure

can only be depended on to represent reality if they are chemically

and physically reasonable. If they are not so, either the data or

the model of the crystal structure is suspect.

Isotropic thermal motion:

Isotropic thermal parameters for the phosphorus atoms, the

Table IV, Inter-atomic distances and boqd angles with standard deviations.

Bonded Distances ( i n 3 )

Cation:

Average

2 291

Table IV (continued), I

Bonded Distances ( i n )

a The correction fo r thermal motion described i n footnote b was not considered t o be s t r i c t l y applicable t o the C-F bond situation. However calculations of corrections based on t h i s r iding motion model (as descriked i n footnote b) indicated t h a t corrections a r e of the order of O.3.A . b Corrected f o r thermal motion assuming t h a t the c 'dorine i s r id ing on t h e rhodium according t o the model used by W.R. h s i n g , K.0, W i n and H.A. fRvy i n t h e i r program ItOrffe, A for t ran c ~ s t a l l o g r a p h i c function and er ror program1I. A version of t h i s p=,garn - was used t o calculate the RMS r a d i a l thermal displacements ( r r ) of tAe involved and a l so the RMS component of thermal dis$axnent (fRh FC, ) i n the direct ion defined by the two atoms involved ( i n t h i s case the rhodium and the chlorine), The equation used was t k e one used i n t h e program O r f f e :

c Though the Rh-CO s i tua t ion does not exactly P i t t h e w d e l of a

Table IV (continued ) . I

Non-bonded Distances ( i n 1) Anion:

Cl(40)-Cl(40) '

Shortest Anion-Cation distance: Cl(40>-~(39> (phenyl(4))

Bond Angles ( i n degrees)

P (3 )-~h(1)-P (4) ( i n t er-Iigand)

c (continued)light atom alone r id ing on a heavy atom, it WZE f e l t * t h a t t h i s model. s t i l l miph t provide a c lose approximation tc t he

Rh-CO bond dis tance correction, A negl igible correction WZE obtair.ed, however.

Table I V (continued 9. I

Bond Angles (in degrees)

carbon atoms of the fluorocyclopentenyl ring (except for C(6), the carbon

farthest from the cationic rhodium) and the phenyl carbon atoms were allowed

to vary in the least-squares procedure. When refinement was terminated, phy-

sically reasonable values were obtained. Parameters for the phosphorus atoms

and for the adjoining carbon atoms of the fluorocyclopentenyl ring are small.

They would appear to be rigidly fixed by bonds to other atoms; hence little

thermal motion would be expected. On the other hand more motion would be ex-

pected for carbon atoms farthest from the phosphorus atoms. The root-mean-

square radial thermal displacements of the phenyl carbon atoms are arranged

in arbitrary classes in Table V. These class divisions are based on the dis-

tances of the carbon atoms from the phosphorus. Thus class 1 contains the

phenyl carbon atoms bonded to the phosphorus, class 2 contains the phenyl

carbon atoms two bonds away from the phosphoms, class 3 contains the phenyl

carbon atoms three bonds away from the phosphorus, and class 4 contains the

carbon atoms farthest from the phosphorus atoms. The generally increasing

amplitude of vibration of the phenyl carbon atoms with increasing distance

from the phosphorus is evidence that their thermal parameters are physically

reasonable.

Anisotropic thermal motion:

Anisotropic thermal parameters as obtained from least-squares refinement

can sometimes be simply accommodating disorder in the crystal, or even per-

haps inaccurate data, rather than any genuine anisotropic motion of the atoms.

Therefore the direction of maximum amplitude of the vibration of an atom must

be considered, as well as the amplitude of the vibration of an atom, in

assessing the legitamacy of any anisotropic thermal parameters. \

The anion: The direction of maximum amplitude of vibration of the chlorine

Table V, Root-mean-square radial thermal displacements of atoms with isotropic thermal parameters.

Phosphorus atoms:

Atoms

p(3 > p(4)

0

displacement (in A)

0*20(1),

0*21(1)

Fluorocyclopentenyl carbon qtoms bonded to the phosphorus atoms :

Atoms displacement (in i)

Fluorocyclopentenyl carbon atoms two bonds from the phosphorus atoms:

0

Atoms displacement (in A)

~(13)

Phenyl carbon atoms: 0

At om displacements (in A) for atoms listed according class to the phenyl ring to which they belong

phenyl 1 phenyl 2 phenyl 3 phenyl t C(16 )-c(21) ~(22 >-c(27) ~(28)-~(33) ~(34>-~(39)

class 1 0.24(1) 0.22(1) 0.20(2) 0,21(2 )

class 3 0.32(1) 0.30(2) 0.28(2) 0.28(2) 0.29(1) 0.28(2) 0.27(2) 0.30(2 1

class4 0.31(2) 0.28(2) 0.26(2) 0*31(2)

atom is at right-angles to the Rh-C1 bond able VI 1; and the amplitude of

this vibration is greater than that of the rhodium atom. This picture of

the chlorine atom riding on the rhodium is physically reasonable, though the

relation of this motion to the vibration of the anion as a whole is obscured

by uncertainty as to the behaviour of the carbonyl group.

It might be expected that at Peast the oxygen of the carbonyl group

would be vibrating as much as or more than the chlorine atom; but o(4.2) ap-

pear3 to he vihrat.in_g 6 t . h cnnsaderahl_y ampl5t.r_?rln t.hzn_ t h e chlgrL?n

atom a able VI). That this inconsistency is the fault of the carbonyl atom

parameters is suggested by the unreliability of the positional parameters

for these atoms (see page ?l), and the high correlation coefficients between

the thermal parameters of one atom of the carbonyl group and the positional

and thermal parameters of the other ca able VII). In fact, the highest cor-

relation coefficient in the correlation matrix is the one (value: 0.60) I

between the z-coordinate of the carbon atom and the z-component of the ther-

mal motion of the oxygen atom. So there is uncertainty as to how the car- - -

bony1 group is vibrating; perhaps this is the fault of the vibration itself--

of the carbonyl group or even of the anion as a whole.

The cation: As for the rhodium atom, its anisotropic parameters are reason-

able. Its amplitude of vibration is comparable to those of the phosphorus

atoms bonded to it which appear to be just as rigidly fixed (Tables V and VI).

Also, the direction of maximum displacement of the rhodium atom is in a dir-

ection normal to the "square plane" of the cation. That this is so is easily

deduced from the thermal ellipsoid plot (figure 3 ) given that the direction

of maximum displacement of the cationic rhodium is at right-angles to the

Table VI. Anisotropic motion analysis

Root-mean-square of atomic displacement along the three principal axes of the thermal e l l ipsoid (A"

Angle between principal axis and a given bond (degree )

Atoms def i n i W bond ,

Cation:

Anion :

Table V I (continued).

Atom Root-mean-square of h E l e between Atoms atomic displacement pr incipal axis defining along the three and a given bond bond I principal axes of the (degree) thermal e l l ipso id (A" >

Table V I I . Correlation coeff ic ients ( 6 ) grea ter than 0.45 between parameters of the carbonyl atoms.

carbon atom parameter oxy-gen atom p a r a .:ter 6

str

uc

tu

re

"b

" 6

w

str

uc

tu

re

a

fig

ure

5.

Alt

ern

ativ

e st

ruc

tura

l p

rop

osa

ls f

or

f6fo

s~

e

(CO) .

Str

uct

ure

"a

w i

s b

ased

on

a sq

uar

e py

ram

idal

ar

rang

emen

t;

stru

ctu

rtj

ft 2 '1

is b

ased

on

a t

rig

on

al

bip

yra

mid

al a

rran

gem

ent.

T

hese

alt

ern

ati

ve

s w

ere

prop

osed

by

W .R

. C

ull

en

(13

).

38

~h(1)-P(3) vector able VI) . Anisotropic thermal parameters for the fluorine atoms may well ,

I be accommodating disorder due to the presence of the other

confomtion of the fluorocyclopentenyl ring. The root-mean-

square displacements of F(8), ~(10), ~(11) and F(12) are greatest

in the directions of fluorine atom positions of a,~~flipped~ con-

formation. In addition, the magnitudes of these displacements e

(Table VI) are not less than the shifts in position (about 0.4~)

these atoms would undergo were the ring flipped.

E. Implications of Two Structural Features of the Cation +

Two structural features of the [~h(f~fos)~] cation have

fnplications concerning other compounds containing the f6fos

ligand . Firstly, the bite of the ligand (intra-ligand P-P distance :

0

3.111(8!~! has a. bearing on the structural proposal for f:fns~e(~~)- 2

(13 1. The nmr spectrum showed that the original ;hetry of the fbfos

ligand was preserved in the latter complex. Cullen et al. have

suggested that this leaves two regular arrangements (figure 5) as

possible structures for this compound, and that the true structure

is one that is intermediate between these two possibilities.

Assuming that the Fe-P distance in fgfos~e(~0)~ is close to

2.21 (it is 2.181 in the compound (n-C5H5)Fe (CO) (f6fos)~n(~~3)3

where f6fos is monodentate(l2)) and assuming that the P-P distance

is no greater than 3.li in f6fos~e(~0)3, the angle subtended at the

Fe atom by the Fe-P vectors would be 9 6 This suggests that

6 t b o a t "

86 c h a i r "

figure 6. Two possible isomers of f6f0sFe(CO)~. , The pucker of the five-membered rings has been

much exaggerated to emphasize the difference between the two conformations.

s t ruc ture (b) i s much closer t o t h e t r u e s t ructure, I

Secondly, the conformations found f o r the five-membered rings of I

t h e cation suggest t ha t other complexes shown t o contain f6fos

puckered, five-membered rings, It is conceivable t h a t two short-

l i ved isomers might appear i n solution. They might be loosely

described a s "boatw and "chairn forms. (see f i g m e 6.) The carboqvl

s t retching ( i r ) spectrum of f 6 f o s ~ e ( ~ ~ ) 3 shows f o m bands, one more

than the number expected f o r a compound with C2, s p n e t r y ( l 4 ) .

Similar ly i n f6fos M ( C O ) ~ complexes four bands are predicted yet

f i v e a r e observed. The evidence here adds c r e d i b i l i t y t o the

suggestion of Cullen and coworkers t h a t this ext ra band could a r i s e

from the presence of two d i s t i n c t isomers i n so lu t ion which have a

long enough l i fe t ime t o be detected by ir spectroscopy.

REFERENCES

42

George H. Stout and Lyle H. Jensen, "X-ray Structure Determination", The Macmillan Company, New York, 1968.

W.R. Cullen and J.A.J. Thompson, Canadian Journal of Chemistry, 48, 1730 (1970).

D.H. Templeton in "International Tables for X-ray Crystallography", vol. 3, The Kynoch Press, Birmingham, England, 1962, p.216. Both real (AFT ) and imaginary (AF") corrections were applied.

"International Tables for X-ray Crystallographytl, vo1.3, The Kynoch Press, Birmingham, England, 1962, p.201.

J.T. Mague and J.P. Mitchener, Inorganic Chemistry, 8, 119 (1969).

L. M. Vallarino, Inorganic Chemistry, 4, 161 (1965).

O.S. Mills and J.P. Nice, J~urnal of Organometallic Chemistry, 10, 337 (1967). - S.J. LaPlaca and J.A. Ibers, Journal of the American Chemical Society, a, 3501 (1963). F.R. Corey, L.F. Dahl and W. Beck, Journal of the American Chemical Society, a, 1202 (1963). Linda R. Bateman, P.M. Maitlis and L.F. Dahl, Journal of the American Chemical Society, 2, 7292 (1969).

L.F. Dahl, C. Martell and D.L. Wampler, Journal of the American Chemical Society, a, 1761 (1961). Private Communication, Dr. R. Restivo.

13. W.R. Cullen, D.A. Harbourne, B.V. Liengme and J.R. Sam, Inorganic Chemistry, t3, 1464 (1969).

14. W.R. Cullen, D.F. Dong, J.A.J. Thompson, Canadian Journal of Chemistry, g, 4673 (1969).

15. F.W.B. Einstein, B.R. Penfold and Q.T. Tapsell, Inorganic Chemistry, 4, 186 (1965).

16. A. Stock and B. Herscovici, Berichte der Deutschen Chemischen Gesellschaft, &3, 414 (1910).

17. J.M. Andrews, JOE. Ferguson and C. J, Wilkins, Journal of Inorganic and Nuclear Chemistry, 5 829 (1963).

18. D.M. Adam and J.B. Raynor, "Advanced Practical Inorganic ChemistryI1, Wiley, London, 1965, p. 94.

19. F,A, Cotton and G, Wilkinson, "Advanced Inorganic Chemistry; a comprehensive textv, Interscience Publishers, New York, 1968, P O 113.

20. J.T. Mague, Inorganic Chemistry, $ 1975 (1969).

21. F.W.B. Einstein and A.M. Svensson, Journal of the American Chemical Society, & 3663 (1969).

22. W.R. Cullen, B.A. Harbourne, B.V. Liengme and J.R. Sam, Inorganic Chemistry, 2, 702 (1970).

23. W.R. Cullen. "Fluorine Chemistry Reviews", vol. 3, Paul Tarrant, ed., Marcel Dekker, Inc . , New York (1969 ) .

24. W.R. Cullen and D.A. Harbourne, Canadian Journal of Chemistry, a, 3371 (1969). 25. W.R. Cullen, D.A. Harbourne, B.V. Liengme and J.R. Sams,

Inorganic Chemistry, €3, 95 (1969).

. -

27. L. Kuhn and E.R. Lippincott, Journal of the krican Chemical Society, '& 1820 (1956).

28. D.J. Millen, C.N. Polydoropoulos and D. Watson, Journal of the Chemical Society, 687 (1960).

29. J.E. Rauch and J.C. Decius, Spectrochimica Acta, 22, 1963 (1966).

30. R.D. Dragsdorf, J.L. Lambert, R.L. Hollis, G.P. Reese and G.L. Stucky, United States Clearinghouse for Federal Scientific and and Technical Information, AD 651647 (reported in U.S .Govt .Res . Develop. Rep., (13 ) , 127 (1967 ) . ) .

APPENDIX

A. A computer program for calculating preliminary cell dimensions from precession photo meusurement s .

46

This i s a program t o calculate preliminary values of c e l l

dimensions from one r e a l angle, two reciprocal angles, and the

reciprocal c e l l elements a*, @and c*. This information can be

e a s i l y obtained from precession photos.

Only one input card i s required. Crystal system need not be

specified.

Input Card ( 9 ~ 8 . ~ ) :

1 - 8 d

9 - 16

17 - 24 l* ) 25 - 32

33 - 40 P

4 1 - 48 * . Y )

49 - 56

57 - 62, "* ', " * specify a i i t'nree

65 - 72 c*

Program w i l l p r in t out a, b, c, a*, F, c*, &, 0, f , < (35 Y

V and v*.

specify any two

specify any one

C A

PROG

RAbiI

TO

CA

LCU

LATE

CEL

L EZ

EXEN

TS F

ROM

PR

EZES

SIO

N M

EA

SUR

EE

mS

D0U

BI;E

PW

XIS

ION

ASTA,BSTA,CSTA,AA,BB,CC,GAM,ALPHyBFP,AWHST,BETS1'

lCST

AR

1 F

O~

~A

T

(9~8.4)

C R

EXA

I~II

IE CE

XL lZ

T..E

lvE1\J

TS T

O C

ONFO

RM T

O A

CA

LCU

LATI

ON

OF

CEL

L EL

ENFN

TS

C ST

AR

TIN

G W

ITH

ALPWLSTAR,BmASTAR,Ghafi,

AND

AST

AR,

BSTA

R AND

CSTA

R (m3

C M

JST

ALS

O B

E RE

NA

MED

) M

=l

IF (

AFA

STD

.EB,

.O)

GO T

O 2

IF

(BTA

STD

.EQ

.O)

GO

TO

3

AST

AX

STA

R

BST

A=B

STA

R

C ST

AX

STA

R G

OT

04

2

AFA

STD

=GM

STD

G

IJA

DEG

ALF

AD

G

C ST

A=A

STA

R A

STA

X ST

AR

BSTA

ZEST

AR

N=O

GO

TO

4

3 BT

AST

D=G

MA

STD

G

lrm-T

AD

G

C ST

AZB

STA

R BS

TAZC

STA

R A

STA

ZAST

AR

N=-

1 C

CON

VER

T TO

R4D

IAN

S FR

OM DEGREES

4 G

AbG

O.O

1745

32PG

EWE%

ALPHST=O.O1745329*AFASTD

BI;;

TST=

O. 0

171+

5329

*BTA

STD

C

CA

JL~l

IlA

'l'i~

; (!i~

~ll

, \'AI~

AklI

~Yb:

RS

. GAh

4MA=

BET

GM

AST

=BET

ST

BETA

=GA

M

ALP

HA

=ALP

H

AW

AST

=ALP

HST

A=

AA

B=CC

C=

BB

AST

AR=

AST

A

BSTA

R=CS

TA

CSTA

R=BS

TA

GO T

O 7

,

6 A=

CC

C =A

A B=

BB

AST

AG

CST

A

C STA

RZA

STA

BS

TAR=

BSTA

B

ETA

ST=B

ETST

G

MA

ST=A

LPH

ST

ALF

AST

=GA

MT

GA

k%IA

=ALP

H

BET

AZB

E'I'

ALP

HA

= ALP

H C PRINT

PARA

E.rn

ERS

7 W

RITE

(^, 8

) A,

B, C

, AST

AR,

BSTA

R,

CSTA

R, A

LPHA

, BET

A, G

AMb'iA

, A

LFA

ST, B

ETA

ST,

1GM

AST

.V.V

STA

.R

8 F

OR

LL

Z? (l

H0,

'A

= t,F

7.2,

t

AN

GST

ROW

I, IOX,

B =

,F

7.2,

A

NG

STRC

, lJ

St,

lOX

,tC

=

t,F

7.2

,t

ANGSTROhJSt/'//lX,tASTAR=

t,F

7.4,

t A

hGST

fi:

~o

w~

-~)'

,~x

,'B

ST

AR

=

t,F

?.l+

,t

ANGSTROW*(-1)',8x,'CSTAR

= t,P

1 37

.4,

' A

NG

ST

RO

&L

~**

(-~

) '///

U,

'ALP

HA

=

',F7.

2,

' D

EGRE

ES ',

8X,

tBFI

1 4

A=

t,F

7.2,

' D

ER

EE

St,

8X

,tG

AlU

=

',F?.

Z,t

DM

;RE

ESf

///U

[,tA

LPH

5A

STA

R =

,F?.

2,

DEG

REES

I, 8X, 1

BFTA

STA

R =

t,F7.

2,

t D

K;R

EES

t, 8

X,

6rG

Ab

~IA

~~

A~

=

',F7.

2,

t D

EGR

EES t

///l

X,

'V

= t,F

10.2

, A

NG

STR

OB

C

WBE

D ',

16X, IV

STA

R =

,Flo

e 7,

t

AN

GST

RO

W*(

-3 ) 1

) ST

OP

B. Description of computer programs used i n t h i s work.

figure B-1.

Flo

w d

iagr

am i

llu

stra

tin

g

sequ

ence

in

whi

ch p

rogr

ams

wer

e u

sed

during t

he

str

uc

ture

det

erm

inat

ion

.

Some of these programs have other functions which are not des- I

cribod here; functions not used are not described.

The output from one of these programs can be used, where neces-

sary, as input for another without change of format.

DSET2: ',A program to calculate goniostat settings for chi-ninety

line-up on a real or imaginary refliction written by E.L. Enwall

at Montana State University and further modified at Simon Frassr

University.11 Input for this program includes indices of the chi-

ninety reflection, the indices of a phi-zero reflection, the real

cell constants, the wavelength of the radiation, and the scan width.

DATAPR: A program to convert raw intensity data into structure

amplitudes, applying Lorentz and polarization corrections. The cor-

rection used is:

i - - 2 sin 28 LP - 1 + cosZ 28

This program was originally written by F.R. Ahmed and has been modi-

fied at Sinon Fraser Universtiy. Input includes F(OOO),

the number of planes, the multiplicities of hOO, OkO, hkO, OOc,

h01, Okl and hkl, the overall scale, and planes cards contain-

ing intensity and scale information.

BUCILS: tlCrystallographic structure factor and full-matrix least-

squares. " This program is a version of the original UCILS (~orth-

western University and University of California, ~rvine) and has

undergone various modifications a t t h e University of Bri t ish

Columbia, and a t Simon Fraser University. Input includes t he r a a l

c e l l dimensions, symmetry information, s ca l e f ac to r and atomic

parameters(both t o be varied i n the least-squares procedure), zz wel l

a s observed s t ruc ture f ac to r information obtained from BUCFIU.

BUCILS was used t o wr i t e t he following f i l e s :

FORFILE: Contains calculated and observed s t ruc tu re fac tc -

informatiorl f o r use i n analysis of R f ac to r s and weights

(program R\NC,ER) and a l so f o r use i n ca lcu la t in r e lect ron Sen-

s i t y by Fourier synthesis (program FORDAP) . ORFFIlE: Contains atomic coordinates and temperature fac5r-rs,

standard deviations f o r these atomic parameters, and t h e ccr re -

l a t i o n matrix f o r t he l a t e s t cycle of least-squares re f inczsn t .

FORDAP: A program t o

ence syntheses of t h e

Pat terson function of

A. Zalkin, Universi ty

compute Fourier syntheses and Fourier d i f f e r -

s t ruc ture factors , a s wel l a s t o compute : ie

FobsZ. This proyram was o r ig ina l ly writtm b+

of California, and has undergone various

modifications including t h a t by J.A. Ibers, and a l so m o d i f i c a t i x s

a t t h e University of Canterbury and the University of Br i t i sh

Columbia. It i s the University of Br i t i sh Columbia version

(January 1969) which was used here. Input includes uni t c e l l ?:men-

sions, symmetry information and the observed s t ruc tu re f ac to r s zc?d

t h e phases of t h e calculated s t ruc tu re f ac to r s f rornthe FORFIE,

I n the case of t h e Patterson function comnutation, the observerl s t ruc-

t u r e fac tors vrere obtained from the RUCFILE.

54

RANGER: A procram t o analyze R fac tors and weiuhts f o r d i f f e r a n t

c lasses of re f lec t ions based on magnit<des, s i n 8 and indices.

This program was ori,n(inally wr i t ten by P.W.R. Corfield a t Nortk-

western University; the University of Br i t i sh Columbia version

(January 1969) used f o r t h i s work i s almost i den t i ca l with a p r e ~ -

ous version of D r . Corfieldls program used a t t h e University or'

Canterbury. Input includes , the approximate m&mum absolute v a u e

of a s t ruc ture factor , the value of (NO-NV)(ie., the number of

observations minus the number of var iables) , the wavelength of

rad ia t ion used, and the information contained i n the FORFILE.

ORFFE2: A program t o ca lcu la te inter-atomic distances a ~ d anyl=s with

standard deviations, and t o ca lcu la te root-mean-square displace3ents

f o r thermal motion of atoms. The o r ig ina l program was writ ter . 3y

W.R. Busing, K.O. Martin and H . A . Levy a t Oak Ridge National Laa-

o r a t o q , Oak Ridge, Tennessee. This v5rsion has undergone nodif i -

cat ions including t h a t a t Simon Fraser University. Input iccl?:3'es

c e l l dimensions with t h e i r standard errors , and the informat io-

contained i n the OFJFII.23, v i z . , t he carrel-ation matrix, and atc-ic

parameters from t h e l a t e s t cvcle of refinement by BUCILS.

ORTEP: "A fo r t r an thermal-ellipsoid p lo t oro-ram f o r c r y s t a l struc-

t u r e i l l u s t r a t i o n s t t , wr i t t en by Car ro l l K. Johnson, Oak Ridge Xltion-

a 1 Laboratory, Oak Ridue, Tennessee. This pronram has been m d i f i e d

s l i e h t l y a t Simon Fraser Universit:r. Input includes atomic cos+inates

and thermal parameters, a s well as un i t c e l l dimensions.

bPANPWN: A procram t o ca lcu la te weiphted mean planes through ztom

55

groups and deviations of atoms from thqse planes. This program was

originally written by M.E. Pippy and F.R. Ahmed of the National

Research Council. The present is the University of British Columbia

version ( ~anuary 1969 ) . Input includes atomic coordinates with estimated standard deviations, and unit cell dimensions.

PARAM: A program to calculate by a least-squares procedure cell

dimensions from 29 measurements of x-ray reflections- Thin pmgrgm

was obtained from Stewart by E.L. Enwall and revised, Montana State

University, April, 1968. Input includes specification of lattice

type, preliminary unit cell dimensions, and indices and 28

measurements of x-ray reflections.

C. The preparations of P2S5BrL and Na2N202*5H20.

57

Two pro jec t s were attempted before the determination of the c r y s t a l

s t ruc tu re of [ ~ h (f6fos )2] [cis-R,h ( c o ) ~ c ~ ~ ] was undertaken. One was t o prepare

and determine the s t ruc ture of c rys t a l s of P2S5Br4. The o ther was t o p r pare '7 and determine the s t ruc ture of c rys t a l s of Na2N2O2*5H2Oe

1. To obtain c rys t a l s and determine t he s t ruc tu re of P2S5Br4.

Discussion: The s t ruc ture of P S B r (lr), which i s obtained from the same 2 6 2

preparative reaction as P S B r (17), was found t o involve a novel phosphorus- 2 5 4

s u l f u r r inc syst-em rnnt,aini-ng S-S hnnds?

( c i s o r t r a n s )

This consis tent with t he statement previously made (17) t h a t P2S6Br2 and

Pg5Br4 must contain S-S bonds i f the coordination of phosphorus with respect

t o su l fu r i s t o be l imited t o four a s expected. Because P2S5Br4 i s prepared

from the same react ion a s P2S6Br2 and under the same conditions, and because

of the l im i t a t i on on the coordination of phosphorus with respect t o su l fur ,

it i s reasonable t o suppose t h a t P2S5Br4 a l s o contains a P S r ing with S-S . - 2 4

bonds. Two l i k e l y s t ruc tures f o r P2S5Br4 based on t h i s r ing s t ruc ture a r e I1

and 111:

It i s noted t h a t there i s a tendency f o r

s t ruc tu re s in the c r y s t a l l i n e s t a t e (eg.

phosphorus pentahalides t o have i on i c

[ P C ~ ~ ] ' [ ~ ~ l d -, [pBr4]+ Br-), thereby

avoiding five-coordination. Because of t h i s general tendency, and pa r t i cu l a r ly

because of the s t ruc tu re of PBr5, s t ruc tu re I1 would seem preferable t o 111.

58

The poss ib i l i t y of the presence of t h i s novel r ing i n the s t ructure , and

the uncertainty as t o the a b i l i t y of phosphorus t o be five-coordinate i n t h i s

s i t ua t ion , made t h i s an a t t r a c t i v e problem.

Preparation: PGS7 first had t o be prepared by the method of Stock and

Herscovici (16). The preparation of P S B r was then attempted by the method 2 5 4

of Andrews , Fergusson and Wilkins (17 ) . The preparation required anhydrous

and oxygen-free conditions, and any product decomposed before su i t ab l e c rys t a l s

were obtained.

2. To obtain c rys t a l s and determine the s t ruc ture of Na2N2OZe5H20.

Discussion: This was a des i rab le project t o undertake f o r the following

reasons: ( i ) t he re has recent ly been new i n t e r e s t i n hyponitrous acid chemistry

(26); ( i i)we wished t o confirm t h a t t he anion had the t rans configuration,

a s indicated by i r evidence(27); ( i i i ) t h e N-0 bond length could be correla ted

with t he NO s t re tch ing frequency (Raman) (27-29). It was expected t o be

r a the r long (1.2-I.$) a s the NO s t re tch ing frequency was ra ther low ( 1 3 9 0 ~ ~ ) ;

( iv ) the hydrogen bonding was of i n t e r e s t . A t t h e time t h i s prodect was

undertaken we were not aware t h a t t he c rys t a l s t ruc ture had already been

determined (30).

Preparation: Na2N202'5H20 was prepared by the method given i n Adams and Ray-

nor (18). The product decomposed before acceptable c rys t a l s were obtained.

D. Description of weighting scheme used in t h i s work.

60

The weighting factor f o r a given observed s t ructure factor

should be a measure of i t s r e l i a b i l i t y . Thus the weight t h a t s t a t i s t i c a l l y

should be used f o r a given observed s t ructure fac tor i s the reciprocal

of its variance:

where 6 i s the standard Fo

deviation f o r Fo, the

observed s t ructure factor .

However, weights a re often taken as being roughly proportional

t o 1 , where the 131 f s are the mean I A F ~ f s f o r d i f fe rent c lasses of IAFP

s t ruc ture fac tors based on magnitudes, sin f3 o r indices. (AF = IFo 1- IF', I ). I f , f o r example, the lzlfs were the meanlhF lfs f o r classes based on

magnitudes of the Fats, then a weighting function would be obtained

from a p lo t of laF( vs . , where the 1% 1 f s a re mean values of (Fo I

f o r c lasses of F,ts of s imilar magnitudes. In t h i s case the weighting

function would be proportional t o

approximately describes the above

the reciprocal of a function which

p lo t :

1 W d Fo A + B I F ~ ) + C I F ~ ~ ~

I n t h i s work, A = 378.3599, B = -3.49X)and C = 0.0112.