~ Pergamon S0277-5387 (96) 00196-9

Polyhedron Vol. 15, No. 24, pp. 4447 4460, 1996 Copyright ~~ 1996 Elsevier Science Ltd

Printed in Great Britain. All rights reserved 0277 5387/96 $15.00+0.00

PREPARATION OF CHIRAL DIIMINO- AND DIAMINODIPHOSPHINE LIGANDS AND THEIR Cu I AND Ag I

COMPLEXES. X-RAY CRYSTAL STRUCTURES OF [Cu(1S,2S-CYCLOHEXYL-P2N2)][PF6] AND [Ag(1R,2R-

CYCLOHEXYL-PzN2H4)] [BF4]

WAI-KWOK WONG* and TAT-WAI CHIK

Department of Chemistry, Hong Kong Baptist University, 224 Waterloo Road, Kowloon, Hong Kong

and

KIN-NING HUI and IAN WILLIAMS

Department of Chemistry, The Hong Kong University of Science and Technology, The Clear Water Bay, Kowloon, Hong Kong

and

XUE FENG and THOMAS C. W. MAK

Department of Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong

and

CHI-MING CHE

Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong

(Received 19 March 1996; accepted 24 April 1996)

Abstract--The interaction of optically pure 1R,2R-diammoniumyclohexane mono-(+)- tartrate and 1 S,2S-diammoniumcyclohexane mono-(-)-tartrate with 2 equiv, of o-(diphe- nylphosphino)benzaldehyde in the presence of 2 equiv, of potassium carbonate in a refluxing ethanol/water mixture gave the optically pure condensation products N,N'-bis[o-(diphe- nylphosphino)benzylidene]-lR,2R-diiminocyclohexane [lR,2R-cyclohexyl-P2N2, (R,R)-I] and N,N'-bis[o- (diphenylphosphino) benzylidene]- 1 S,2S-diiminocyclohexane [1 S,2S- cyclohexyl-P2N2, (S,S)-I], respectively, in good yield. Reduction of optically pure (R,R)-I and (S,S)-I with NaBH4 in ethanol gave the optically pure reduced products N,N'-bis[o- (diphenylphosphino) benzylidene]- 1R,2R-diaminocyclohexane [1R,2R-cyclohexyl-P2N2H4, (R,R)-II] and N,N'-bis[o-diphenylphosphino)benzylidene]-I S,2S-diaminocyclohexane [1S,2S-cyclohexyl-P2N2H4, (S,S)-II], respectively, in good yield. The coordination behav- iour of I and II toward salts of Cu ~ and Ag ~ have been examined. The interaction of [Cu(CH3CN)4][X] (X = C104, PF6)with 1 equiv, of optically pure L4 [L4 = (R,R)-I, (S,S)-

* Author to whom correspondence should be addressed.

4447

4448 WAI-KWOK WONG et al.

| , (R,R)-II and (S,S)-II] gave the corresponding optically pure [CuL4] [X] complexes, III VI [Ilia, L 4 = (R,R)-I, X = PF6, lllb, L4 = (R,R)-I, X = C104, IV, L4= (S,S)-I, X = PF~, ; Va, L4 = (R,R)-II, X = PF6, Vb, L4 = (R,R)-II, X = C104, VI, L4 = (S,S)-Ii, X = PF6 ], in good yield. For the Cu ~ complexes, the L 4 ligand acted as a tetradentate ligand. However, a variable-temperature 3tp [IH] NMR study of l l lb shows that at ambient temperature one of the imino groups of the tetradentate ligand undergoes rapid dissociation to form a tridentate ligand. The interaction of AgBF4 with 1 equiv, of optically pure L4 [L4 = (R,R)-I, (S,S)-I, (R,R)-II and (S,S)-II] gave the corresponding optically pure [AgL4][BF4] complexes, VII-X [VII, L4 = (R,R)-I ; VIII, L4 = (S,S)-I; IX, L4 = (R,R)-II; X, L4 = (S,S)-II], in good yield. For the Ag ~ complexes, the L4 ligand acted as a tetradentate ligand with the two amino groups coordinated unsymmetrically to the silver. A variable temperature 3Jp [iH] NMR study of VIi suggests that at high temperature the complex exists as a tri-coordinated complex. The structures of IV and IX were established by X-ray diffraction studies. Copyright 42;, 1996 Elsevier Science Ltd

Kevwor&: copper(l); silver(l); chiral diiminodiphosphine; chiral diaminodiphosphine; X-ray structure; solution dynamic.

We have been interested in the chemistry ofdiimino, diamino- and diamidodiphosphine ligands as these are polydentate ligands containing both phos- phorus and nitrogen donor atoms, which could behave as soft and hard bases, respectively, and act as bridging ligands for the preparation of het- erometallic complexes with hard and soft metal cen- tres. We have shown that these ligands exhibit a very rich coordination chemistry and can behave as bridging, bi, tri and tetradentate ligands depending on the reaction conditions. ~ s We would also like to extend our study to the chiral diimino-, diamino- and diamidodiphosphine ligands. In this paper, we report a simple, high yield method for the prep- aration of optically pure N,N'-bis[o(diphenyl- p h o s p h i n o ) b e n z y l i d e n e ] - I R ,2R,d i iminocyclo- hexane [1R,2R-cyclohexyl-P2N> (R,R)-I], N,N' bis[o-(diphenylphosphino)benzylidene]-I S,2S-di- iminocyclohexane [lS,2S-cyclohexyl-P2N2, (S,S)- I], N,N'-bis[o-diphenylphosphino)benzylidene]- 1 R, 2R,diaminocyclohexane [1 R,2R-cyclohexyl-P2N2 H4, (R,R)-II] and N,N'-bis[o-(diphenylphos- phino)benzylidene]- l S,2S-diaminocyclohexane [1S, 2S-cyclohexyl-P2N2H4, (S,S)-II] and their cor- responding Cu ~ and Ag ~ complexes.

RESULTS A N D D I S C U S S I O N

Preparation of chiral diimino- and diaminodi- phosphine ligan&

(i) (R,R)- and (S,S)-I. The interaction of 1R,2R- diaminocyclohexane, generated in situ from the reaction of 1R,2R-diammoniumyclohexane mono- (+)- tar t ra te salt with 2 equiv, potassium carbon-

ate, with 2 equiv, of o-(diphenylphos- phino)benzaldehyde in refluxing water/ethanol mixture gave an orange solid, 1R,2R,-cyclohexyl- P2N2 [(R,R)-I], with specific rotation [cq~ ° of 9.04' (c 1, CH2C12) in 77% yield. The IR spectrum of (R,R)-I exhibited a strong Vc N stretch at 1632 cm ~. In addition to signals from the phenyl and cyclohexyl protons, the ~H NMR spectrum exhi- bited a doublet (Jp H = 4.1 HZ) and a multiplet of relative intensity 2 : 2 at 6 8.50 and 2.98 ppm for the imino H C = N and the cyclohexyl N - - C H protons, respectively. The 3~p [~H] NMR spectrum of (R,R)- I exhibited a singlet at c5 - 11.3 ppm. The LRMS- FAB spectrum of (R,R)-I exhibited the ( M + I ) peak at m/z of 659. The corresponding 1S,2S- cyclohexyl-PEN2, (S,S)-I, was synthesized similarly from 1S,2S-diammoniumcyclohexane mono- (+) - tartrate salt in 70% yield. (S,S)-I exhibited a spec- ific rotation [~]~0 of - 9 . 0 4 (c 1, CH2CI2). The IR spectrum of (S,S)-I exhibited a strong VC--N stretch at 1626 cm *. In addition to signals from the phenyl and cyclohexyl protons, the *H N MR spectrum exhibited a doublet (Jp H = 4.1 HZ) and a multiplet of relative industry 2 :2 at g 8.68 and 3.01 ppm for the imino H C = N and the cyclohexyl N - - C H protons, respectively. The 31p [IH] NMR spectrum of (S,S)-I exhibited a singlet at 6 - 11.5 ppm. The LRMS-FAB spectrum of (S,S)-I exhibited the ( M + I ) peak at m/z of 659. Based on the above spectroscopic data, the following structures are pro- posed for (R,R)-I and (S,S)-I :

(ii) (R,R)- and (S,S)-II. The interaction of optically pure (R,R)-I with excess NaBH+ in reflux- ing ethanol gave a pale yellow solid, I R,2R- cyclohexyl-P2N2H4 [(R,R)-II], with specific rotation [~]~ of - 2 9 . 2 3 ' (c 1, CH2CI2) in 55%

Preparation of chiral diimino- and diaminodiphosphine ligands

=N'"; NN=C~ N

PP½ p ½ p J

1R, 2R-cyclohexyl-P 2N2, (R,R)-I

H. H , , , . ~ H __H

] S, 2S-cyclohexyl-P 2N2, (S,S)-I

4449

yield. The IR spectrum of (R,R)-II exhibited a vN, stretch at 3048 cm 1. In addition to signals from the phenyl and cyclohexyl protons, the ~H N M R spectrum exhibited two doublets of relative inten- sity 2:2 at 6 3.90 (d, J = 13.8 Hz) and 3.73 (d, J = 13.8 Hz) ppm for the PhCH2N-- protons ; and a broad singlet of relative intensity 2 at 6 1.78 ppm for the - - N H protons. The 3~p [1H] NMR spectrum of (R,R)-II exhibited a singlet at 6 - 13.7 ppm. The LRMS-FAB spectrum of (R,R)-II exhibited the ( M + 1) peak at m/z of 663. The corresponding 1S,2S-cyclohexyl-P2N2H4, (S,S)-II, was syn- thesized similarly with optically pure (S,S)-I in 60% yield. (S,S)-II exhibited a specific rotation [a]~o of 26.63' (c 1, CH2C12). The IR spectrum of (S,S)-II exhibited a VN H stretch at 3048 cm-~. In addition to signals from the phenyl and cyclohexyl protons, the ~H N M R spectrum exhibited two doublets of relative intensity 2:2 at 6 3.91 (d, J = 13.8 Hz) and 3.73 (d, J = 13.8 Hz) ppm for the PhCH2N-- protons ; and a broad singlet of relative intensity 2 at 6 1.78 ppm for the - - N H protons. The 31p [IH] NMR spectrum of (S,S)-II exhibited a singlet at 6 - 13.7 ppm. The LRMS-FAB spectrum of (S,S)-II exhibited the (M + 1) peak at m/z of 663. Based on the above spectroscopic data, the following struc- tures are proposed for (R,R)-II and (S.S)-II :

1R,2R-cyclohexyl-P zN2H4 , (R,R)-II

Preparation of Cu I complexes

(i) [Cu(1 R,2R-cyelohexyl-P2N2)] [PF6] (llIa). When [Cu(CH3CN)a][PF6] was treated with 1 equiv, of (R,R)-I in CH2C12 for 16 h, work-up gave

orange crystals of stoichiometry [Cu(1R,2R- cyclohexyl-P2N2)] [PF6] (Ilia) with specific rotation [7]~0 of -269.08 ° (c 0.5, CH2C12) in good yield (75%) after recrystallization from a CH2C12/diethyl ether mixture. The IR spectrum of I l ia exhibited a strong Vc= N absorption at 1640s cm t for the imino groups. The ~H NMR spectrum of I l ia exhibited a singlet and a multiplet of relative intensity 2 : 2 at 6 8.43 and 2.99 ppm for the imino H C ~ N and the cyclohexyl N - - C H protons, respectively. The ambient-temperature 31p [IH] NMR spectrum exhi- bited a broad singlet (width at half-height 135.7 Hz) and a heptet (Jp v = 711.3 Hz) at ~ -0 .3 and -142.4 ppm for the phosphorus of the (R,R)-I ligand and the PF6 anion, respectively. The per- chlorate salt, [Cu(1R,2R-cyclohexyl-P2N2)][ClO4] (lllb), was prepared similarly in good yield (70%) from [Cu(CH3CN)4][C104] and (R,R)-I. Com- pound lllb exhibited a specific rotation [e]2o of -264.0 ~ (c 0,5, CH2C12). The ambient-temperature 3tp [~H] NMR spectrum of l l lb exhibited a broad singlet (width at half-height 131.1 Hz) at 6 - 1 . 0 ppm for the phosphorus of the (R,R)-I ligand. Since the corresponding [Cu(1 R,2R-cyclohexyl- PzN2)][PF6] (IV) complex is a tetrahedral complex (vide &['ra), a tetrahedral geometry is assigned to Ilia and lllb.

CH2 NH ¢ ""

~ P P l ~ 2 Ph2P /

1S, 2S-cyclohexyl-P2N2H4, (S,S)-II

Compound l l lb exhibited fluxional behaviour in solution. Variable-temperature 3~p [~H] NMR spec- tra of IIIb in CD2C12, shown in Fig. 1, revealed that on lowering the temperature, the broad singlet (width at half-height 131.1 Hz) at 6 - 1 . 0 ppm sharpened and shifted upfield. At - 80°C, the broad

4450 WAI-KWOK WONG et al.

O°C

_40°C

-60°C

L /( _80°C

5 0 -5 -10

Fig. 1. Variable temperature 3~p [~H] NMR spectra of [Cu(1R,2R-cyclohexyl-PaN2)][ClO4].

signal sharpened (width at half-height 29.1 Hz) and shifted upfield to 6 - 2 . 0 ppm. A possible intra- molecular exchange process for the solution dynamic behaviour of IIIb is shown in Scheme 1. At low temperature, IIIb exists as a tetrahedral complex, with the (R,R)-I ligand acting as a tet- radentate ligand. As the temperature increases, one of the imino groups of the tetradentate (R,R)-I ligand dissociates from the coordination sphere of the Cu atom and the ligand becomes a tridentate ligand. At ambient temperature, the coordinated and the uncoordinated imino group undergo a facile intramolecular exchange. Similar dynamic behaviour had also been reported for related diim- inophosphine Cu ~ complexes. 4,6

(ii) [Cu(1S,2S-cyclohexyl-P2N2)][PF6] (IV). When [Cu(CH3CN)4][PF6] was treated with 1

equiv, of (S,S)-I in refluxing CH2C12 for 16 h, work- up gave orange crystals of stoichiometry [Cu(l S,2S-cyclohexyl-PzN2)] [PF6] (IV) with spec- ific rotation [~]20 of 266.87 o (c 0.5, CH2C12) in good yield (75%) after recrystallization from a CH2C12 diethyl ether mixture. The IR spectrum of IV exhi- bited a strong Vc= N absorption at 1638s cm ~ for the imino groups. The 1H N M R spectrum of IV exhibited a singlet and a multiplet of relative inten- sity 2 :2 at 6 8.42 and 2.99 ppm for the imino H C ~ N and the cyclohexyl N - - C H protons, respectively. The ambient-temperature 3ip [~H] N MR spectrum exhibited a broad singlet (width at half-height 148.6 Hz) and a heptet (Jp v = 711.3 Hz) at 6 - 0 . 5 and - 142.5 ppm for the phosphorus of the (S,S)-I ligand and the PF6 anion, respectively. Spectroscopic data suggest that similar to III, IV

Preparation of chiral diimino- and diaminodiphosphine ligands _ +

.P /-N%. ,,"

, , , ,M\ \ N " e

+

4451

M= Cu(I), Ag(I) ; p N N P = 1R,2R-cyclohexyl-P2N 2 IS, 2S-cyclohexyl-P 2N2 IR, 2R-cyclohexyl-P 2N2H4 IS, 2S-cyclohexyl-P 2N2H4

Scheme 1. Proposed mechanism for the dynamic behaviour of Cu I and Ag 1 complexes.

also undergoes a facile intramolecular exchange at ambient temperature as shown in Scheme 1.

The structure of IV was established by an X-ray diffraction study. Crystals of stoichiometry { [Cu( 1 S, 2 S-cyclohexyl-PzN2)] [PF6] } 2" CHzC12 • (C2H5)20 suitable for X-ray diffraction study were grown from a mixture of CHzClz/diethyl ether. A perspective drawing of IV is shown in Fig. 2. Selected bond lengths and bond angles are listed in Table 1. All bond lengths and bond angles are normal. The solid-state structure of IV can be described as distorted tetrahedral with the ligand acting as a tetradentate ligand. The C(30b)--N(3b) and C(40b)--N(4b) distances of 1.268(11) and 1.262(11) A, respectively, are typical of C - - N distance. The structure further reveals that the two chiral carbons C(31b) and C(41b) of the cyclohexyl ring adopt a S configuration.

(iii) [Cu(1R,2R-cyclohexyl-PzNzH4)][PF6] (Va). When [Cu(CH3CN)4][PF6] was treated with 1 equiv, of (R,R)-II in refluxing CHzCI2 for 16 h, work-up gave white crystals of stoichiometry [Cu(1R,2R-cyclohexyl-P2N2H4)][PF6] (Va) with specific rotation [~]20 of 85.90 ° (c 0.5, CH2C12) in good yield (75%) after recrystallization from a CH2Clz/diethyl ether mixture. The IR spectrum of Va exhibited a strong vy_n absorption at 3281 s cm- for the amino groups. The ~H NMR spectrum of Va exhibited a doublet of doublet (J = 13.0 Hz, J = 4.1 Hz) and a broad doublet (J = 13.0 Hz) of relative intensity 2:2 at 6 3.97 and 3.87 ppm, respectively, for the PhCHzN-- protons; and a broad singlet of relative intensity 2 at 6 2.57 ppm for the - - N H protons. The ambient-temperature 3~p [~H] NMR spectrum of Va exhibited a broad singlet (width at half-height 131.1 Hz) and a heptet (JP v = 707.3 Hz) at 6 - 5.8 and - 142.4 ppm for the phosphorus of the (R,R)-II ligand and the PF 6 anion, respectively. The perchlorate salt, [Cu(1R,2R-cyclohexyl-P2N2H4)][CIO4] (Vb), was

prepared similarly in good yield (70%) from [Cu(CH3CN)4][C104] and (R,R)-II. Compound Vb exhibited a specific rotation [~]20 of 84.35 ° (c 0.5, CH2C12). The ambient-temperature 3~p [~H] NMR spectrum of Vb exhibited a broad singlet (width at half-height 131.0 Hz) at 6 - 6 . 0 ppm for the phosphorus of the (R,R)-II ligand. This suggests that similar to III, V has a tetrahedral geometry and undergoes a facile intramolecular exchange at ambient temperature as shown in Scheme 1.

(iv) [Cu(1S,2S-cyelohexyl-P2N2H4)][PF6] (VI). When [Cu(CH3CN)4][PF6] was treated with 1 equiv, of (S,S)-II in refluxing CH2CI 2 for 16 h, work-up gave white crystals of stoichiometry [Cu(1 S,2S-cyclohexyl-PzN2H4)][PF6] (VI) with specific rotation [~]20 of - 86.35 ° (e 0.5, CHzCI2) in good yield (75%) after recrystallization from a CHzClz/diethyl ether mixture. The IR spectrum of VI exhibited a strong V~n absorption at 3288s cm- for the amino groups. The ~H N M R spectrum of VI exhibited a doublet of doublets (J = 13.2 Hz, J = 3.8 H z ) and a broad doublet (J = 13.2 Hz) of relative intensity 2:2 at 6 4.05 and 3.95 ppm, respectively, for the PhCHzN-- protons; and a broad singlet of relative intensity 2 at 6 2.63 ppm for the - - N H protons. The ambient-temperature 3~p [~H] N M R spectrum exhibited a broad singlet (width at half-height 134.0 Hz) and a heptet (JP-r = 707.3 Hz) at 6 -6 .1 and -142.3 ppm for the phosphorus of the (S,S)-II ligand and the PF6 anion, respectively. Spectroscopic data suggest that the structure of VI is similar to that of V and that VI also undergoes a facile intramolecular exchange at ambient temperature as shown in Scheme 1.

Preparation of Ag I complexes

(i) [Ag(1R,2R-cyclohexyl-P2Nz)][BF4] (VII). When AgBF4 was treated with 1 equiv, of (R,R)-I in refluxing CH2C12 for 16 h, work-up gave light

4452

C(55b)

C(46b)

C(13b)

C(51b)

C(62b)

C(63b)

C(64b)

WAI-KWOK WONG et al.

C(43b)

C(42b)/

C(41b) C(52b)

C(33b)

C(32b)

C(31b)

C(40b) C(83b)

P(Ib) P(2b)

C(61b) C(71 b)

~k~F(4b)~~F(6b~

~ F(3b)

F(2b)

~3~i)34b) Z C(35b)

C(21b) ~.,.,¢-~C(85b)

C(22b)

C(66b)

i)C(65b)

C(72b)

C(73b)

C(76b)

C(75b)

C(74b)

C(23b)

Fig. 2a. A perspective drawing of [Cu(1S,2S-cyclohexyl-P2N2)][PF6] (IV).

yellow crystals of stoichiometry [Ag(1R,2R- cyclohexyl-P2N2)][BF4] (VII) with specific rotation [~]20 of - 51 . 15 ' (c 0.5, CH2C12) in good yield (75%) after recrystallization from a CH2Cl2/diethyl ether mixture. The IR spectrum of VII exhibited a strong vc-N absorption at 1632s cm 1 for the imino groups. The ~H NMR spectrum of VII exhibited a singlet and a multiplet of relative intensity 2 : 2 at 6 8.48 and 3.34 ppm for the imino H C ~ N and the cyclohexyl N - - C H protons, respectively. The ambient-temperature 31p [iH] NMR spectrum ex- hibited two doublets (Jp p = 40.6 Hz) of equal intensity at 6 11.3 and 16.2 ppm, indicating that both phosphorus atoms of the ligand were coor- dinated and non-equivalent. This suggests that the l R,2R-cyclohexyl-P2N2 ligand behaves either as a tridentate ligand with the two phosphino groups and one of the two imino groups coordinated to the

Ag atom and the remaining imino group unco- ordinated as in the case of [Ag(binap-P2N2) ] [BF4],4 or as a tetradentate ligand with the two imino groups bonded unsymmetrically to the Ag atom as in the case [Ag(1 R,2R-cyclohexyl-P2N2H4)] [BF4] (IX) (vide infi'a). In terms of steric environment, the 1R,2R-cyclohexyl-P2N2 ligand is closer to that of the l R,2R-cyclohexyl-P2N2H4 ligand than that of the binap-P2N2 ligand. It is expected that the geometry of Vll is similar to that of IX, which has a tetrahedral structure. Thus, a tetrahedral geometry is assigned to VII.

Compound VII exhibited temperature-depen- dent 3~p [iH] N MR spectra. The variable-tem- perature 3~p [1H] N M R spectra of V|l in DMSO-d6 shown in Fig. 3 revealed that the two doublets for the two non-equivalent phosphino groups became equivalent and coalesced at 140~C. The solution

Preparation of chiral diimino- and diaminodiphosphine ligands

o)

4453

Fig. 2b. A perspective drawing of { [Cu(1S,2S-cyclohexyl-P:N2)] [PF6] } 2" CH2CI:" (C:Hs)20.

Table 1. Selected bond lengths (A) and angles (:) for IV. The values of the second molecule are in square brackets

Cu(lb)--P(lb) 2.219(2) [2.214(2)] Cu(Ib)--P(2b) 2.217(2) [2.198(2)] Cu(lb)--N(3b) 2.057(6) [2.033(6)] Cu(Ib)--N(4b) 2.095(5) [2.074(6)] N(3b)--C(30b) 1.268(11) [1.259(11)] N(3b)--C(31b) 1.476(8) [1.478(8)] N(4b)--C(40b) 1.262(11) [1.251(11)] N(4b)--C(41b) 1.491(9) [1.481(9)]

P(lb)--Cu(lb)--P(2b) 129.7(1) P(lb)--Cu(1 b)--N(3b) 129.7(2) P(I b)--Cu(1 b)--N(4b) 90.3(2) P(2b)--Cu(l b)--N (3b) 93.5(2) P(2b)--Cu(lb)--N(4b) 124.7(2) N(3b)--Cu(lb)--N(4b) 81.9(2) C(30b)--N(3b)--C(31b) 120.3(6) C(40b)--N (4b)--C(41 b) 121.4(6) N(3b)--C(30b)--C(34b) 128.1 (6) N(4b)--C(40b)--C(44b) 126.5(6)

[126.8(1)] [126.6(2)] [91.4(2)1 [95.4(2)]

[129.4(2)] [82.2(2)]

[120.7(6)] [121.1(6)] [128.0(6)] [126.3(7)]

dynamic behaviour of VII can also be explained by the proposed mechanism shown in Scheme 1. At ambient temperature, VII exists in solution as a tetrahedral complex with the two imino groups coordinated to the silver atom unsymmetrically. As the temperature increases, one of the two imino

groups of the tetradentate (R,R)-I ligand slowly dissociates from the coordination sphere of the sil- ver atom and the ligand becomes a tridentate ligand. At high temperature, VII exists as a tri- coordinated complex with the coordinated and the uncoordinated imino groups of the tridentate (R,R)-I ligand undergoing a facile intramolecular exchange.

(ii) [Ag(lS,2S-o,clohexyl-P2N2)][BF4] (VIII). When AgBF4 was treated with 1 equiv, of (R,R)-I in refluxing CH2C12 for 16 h, work-up gave light yellow crystals of stoichiometry [Ag(1S,2S- cyclohexyl-PzN2)] [BF4] (VIII) with specific rotation [~]20 of 61.86' (c 0.5, CH2C12) in good yield (75%) after recrystallization from a CH2C12/diethyl ether mixture. The IR spectrum of VIII exhibited a strong VC~N absorption at 1626s cm- 1 for the imino groups. The LH N M R spectrum of V | l l exhibited a singlet and a multiplet of relative intensity 2 : 2 at 6 8.52 and 3.08 ppm for the imino HC~-~-N and the cyclohexyl N - - C H protons, respectively. The ambient-temperature 31p [IH] N MR spectrum ex- hibited two doublets (Jp p = 36.6 Hz) of equal intensity at fi 10.5 and 15.3 ppm, indicating that both phosphorus atoms of the ligand were coor- dinated and non-equivalent. Spectroscopic data suggest that the structure of VIII is similar to that of VII and thus, a tetrahedral structure is also assigned to VIII.

(iii) [Ag(l R,2R-cyclohexyI-P2N2H4)][BF4] (IX).

4454 WAI-KWOK WONG et al.

30oc

.,+++,.,,.++~.~~~'+,+-,",'~"~,',',-+,.+-,+~,J'.,r ~ + 600~

90°C

~ X 140°C

, i ) / ' ~^,..

i + i ] i i + i l i i i i l + + i i I i i i i l 20 15 10 5 0 Fig. 3. Variable temperature 3119 [IH] NMR spectra of [Ag(1R,2R-cyclohexyl-P2N2)][BF4].

When AgBF4 was treated with l equiv, of (R,R)-II in refluxing CH2CI 2 for 16 h, work-up gave white crystals of stoichiometry [Ag(1R,2R-cyclohexyl- P~NzH4)][BF4] (IX) with specific rotation M 2° of 42.80 ° (e 0.5, CH2C12) in good yield (70%) after recrystallization from a CH~C12/diethyl ether mixture. The IR spectrum of IX exhibited a strong vy_H absorption at 3288s cm -~ for the amino groups. The 1H NMR spectrum of IX exhibited two multiplets of relative intensity 2:2 at 6 3.91 and 3.72 ppm for the PhCH2NH-- protons; and a broad singlet of relative intensity 2 at 6 2.37 ppm for the - - N H protons. The ambient-temperature 31p [1H] NMR spectrum exhibited two doublets (Jp p = 28.5 Hz) of equal intensity at 6 - 0 . 4 and 3.5 ppm, indicating that both phosphorus atoms of the ligand were coordinated and non-equivalent. The structure of IX was established by an X-ray diffraction study. Crystals of stoichiometry [Ag (1R,2R-cyclohexyl-P2N2H4)] [BF4] • CH2C12 suit- able for X-ray diffraction were grown from a mixture of CHzC12/diethyl ether. A perspective

drawing of IX is shown in Fig. 4. Selected bond lengths and bond angles are listed in Table 2.

The solid-state structure of IX is consistent with the spectroscopic data and shows the complex to be a distorted tetrahedral species with the two amino groups bonded unsymmetrically to the silver atom. The Ag--P(1) and Ag--P(2) bond distances 2.446(5) and 2.440(5) A, respectively, and are very similar. The Ag--N(1) and Ag--N(2) bond dis- tances are 2.382(13) and 2.476(12) A, respectively, and are longer than normal Ag- -N bond of 2.20 A indicating weak interactions between the silver atom and the two amino groups. The two Ag- -N bond distances are significantly different [0.094(25) A]. This difference in bonding interaction in the solid state is significant and is believed to persist in solution, since the 3~p [1H] NMR data suggested non-equivalent environment for the two phos- phorus atoms.

(iv) [Ag(1S,2S-cyclohexyl-P2N2H4)] [BF4] (X). When AgBF4 was treated with 1 equiv, of (S,S)-II in refluxing CH2C14 for 16 h, work-up gave white

Preparation ofchiral diimino- and diaminodiphosphine ligands

C(37)

C(36} ~ C(41,,-~'~ C(42)

C(35)

C ( 3 2 ~

C(31)

C(30)

0(38) 0(40)

C(33) C(39) C(431

C(44)

F(2) F(1)

C ( 8 1 ~ F(4)

C(: C(2)

C(3)

C(25) C(26) ~,,) / / a{1 , "~ I ) !

~J '- ' ,~r~'g ",%r--~ C(7) ~ ~'" C(6)

C(23) Ci22) C(1~ C(17)

C(4)

IC(16) ~ C(10)

C(14"~,~ C(11) C1(2)

C(13) C(12) C1(1) C(45)

Fig. 4. A perspective drawing of [Ag(l R,2R-cyclohexyl-P2NzH4)][BF4] • CH2CI2(IX" CH2C12).

4455

Table 2. Selected bond lengths (A) and angles (°) for IX

Ag(1)--P(I) 2.446(5) Ag(1)--P(2) 2.440(5) Ag(1)--N(I) 2.382(13) Ag( 1)--N (2) 2.476(12) N(1)--C(I) 1.427(20) N(2)--C(2) 1.494(19) N(1)--C(7) 1.508(20) N(2)--C(8) 1.503(21)

P(1)--Ag(I)--P(2) 136.5(2) P(1)--Ag(1)--N(1) 88.6(3) P(1)--Ag(I)--N(2) 114.7(3) P (2)--Ag(l)--N (1) 134.7(3) P(2)--Ag(1)--N(2) 86.8(3) N( 1 )--Ag(1 )--N (2) 73.2(4) C(1)--N(1)--C(7) 115.1(12) C(2)--N(2)--C(8) 112.5(12) N(1)--C(7)--C(10) 109.7(14) N(2)--C(8)--C(28) 112.3(13)

crystals of stoichiometry [Ag(1S,2S-cyclohexyl- P2N2H4)][BF4] (X) with specific rotation [c~]~ ° of -43.18 '~ (c 0.5, CH2C12) in good yield (65%) after

recrystallization from a CH2Clz/diethyl ether mixture. The IR spectrum of X exhibited a strong VN H absorption at 3301s cm -1 for the amino groups. The ~H N M R spectrum of X exhibited two multiplets of relative intensity 2:2 at 6 3.90 and 3.76 ppm for the PhCH2NH-- protons; a broad singlet of relative intensity 2 at 6 2.39 ppm for the - - N H protons. The ambient-temperature 31p [1H] NMR spectrum of exhibited two doublets (Jp_p = 28.5 Hz) of equal intensity at 6 0.4 and 4.0 ppm, indicating that both phosphorus atoms of the ligand were coordinated and non-equivalent. Spectroscopic data suggest that the structure of X is similar to that of IX and thus, a tetrahedral struc- ture is assigned to X.

E X P E R I M E N T A L

Microanalyses were performed by the Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, China. IR spectra (KBr pellets) were recorded either on a Hitachi 270-30 IR spec- trometer or on a Nicolet Nagna-IR 550 spec- trometer; data are given in cm -~. N M R spectra were recorded on a JEOL EX270 spectrometer.

4456 WAI-KWOK WONG et al.

Chemical shifts of3JP NMR spectra were referenced to external 85% H3PO4. Chemical shifts of 1H NMR spectra were referenced to internal deut- erated solvents and then recalculated to TMS = 6 0.00 ppm. Low-resolution mass spectra (LRMS) were obtained on a Finnigan MAT SSQ-710 spec- trometer in FAB (positive) operation mode and are reported as m/z. Optical rotation was measured on a JASCO DIP-1000 polarimeter with concentration given in grams of sample per 100 cm -~ of the solvent.

All operations were carried out under nitrogen or in vacuo. All chemicals used were of reagent grade. Solvents were dried by standard procedures, distilled and deaerated prior to use. Optically pure 1R,2R-diammoniumyclohexane mono-(+)- tar - trate and l S,2S-diammoniumcyclohexane mono- ( - ) - t a r t r a t e were prepared according to literature method. 7

Preparation of ligands

(i) 1R,2R-cyclohexyl-P2N2, (R,R)-I. A solution of 1R,2R-diammoniumyclohexane mono-(+)- tar - trate (1.0 g, 3.8 mmol) and potassium carbonate (1.05 g, 7.6 mmol) in a 1 : 2 mixture of water/ethanol (60 cm 3) was refluxed for 3 h in a 250 cm 3, two-neck round-bottomed flask equipped with a pressure- equalizing additional funnel and a condenser fitted with a nitrogen inlet. Then a solution of o-(diphe- nylphosphino)benzaldehyde (2.2 g, 7.6 mmol) in ethanol (30 cm 3) was added dropwise to the reac- tion mixture over a period of 30 min. The resultant yellow solution was refluxed further for another 3 h and cooled down to room temperature. Water (20 cm 3) was then added to the reaction mixture to give creamy yellow solids after cooling down to OC for several hours. The crude product was collected by suction filtration and washed with cold ethanol. The crude product was redissolved in CH2C12 (20 craB), which was washed with water (2 x 20 cm3), dried over anhydrous Na2SO4 and filtered. Removal of the solvent from the filtrate in vacuo gave a yellow solid. Yield : 1.9 g, 77%. m.p. 83-85"C. Found : C, 79.2; H, 6.1; N, 3.6. Calc. for (C44H40N2 P2) '0.5H20: C, 79.2; H, 6.1 ; N, 4.2%. IR (KBr): 3048m, 2844m, 2748m, 1688vs, 1582m, 1458s, 1428s, l190s, 740s, 688s cm -I. 3Jp [1H] NMR (CDC13): 6 -11 .3 (s) ppm. IH NMR (CDC13): 6 8.50 (2H, d, Jp n = 4.1 Hz), 6.70-7.66 (28H, m), 2.98 (2H, m), 1.18 1.58 (8H, m) ppm. LRMS (FAB: +ve) re~z: 659 ( M + I ) . [e]20 = 9.04 c (c 1, CH2C12).

(ii) l S,2S-eyclohexyI-P2N2, (S,S)-I. The pro- cedure was similarly to that of (R,R)-I. 1S,2S-diam- moniumyclohexane mono- (+ )-tartrate (1.0 g, 3.8

mmol), potassium carbonate (1.05 g, 7.6 mmol) and o-(diphenylphosphino)benzaldehyde (2.2 g, 7.6 mmol) were used. Yield: 1.74 g, 70%. m.p. 80- 82'C. Found: C, 79.3; H, 6.0; N, 3.7. Calc. for (C44H40N2P2) "0.5H20: C, 79.2; H, 6.1 ; N, 4.2%. 1R (KBr): 3048m, 2924s, 2848s~ 1626s, 1430s, 1174s, 734s, 688s, 480m cm 1. 3~p [IH] NMR (CDCI3): 6 -11 .5 (s) ppm. tH NMR (CDCI3): 6 8.68 (2H, d, JP--H = 4.1 Hz), 6.78 7.76 (28H, m), 3.10 (2H, m), 1.22-1.58 (8H, m) ppm. LRMS (FAB" + v e ) m / z " 659 ( M + I ) . [~]~0 = -9.04'; (c 1, CH2C12).

(iii) lR,2R-cvclohexyl-P2N2H4, (R,R)-II. A solution of (R,R)-I (0.79 g, 1.21 retool) and sodium borohydride (0.27 g, 7.3 mmol) in absolute ethanol (40 cm ~) was refluxed for 24 h to give a creamy yellow solution. Removal of the solvent gave a pale yellow residue which was extracted with CH2C12 (2 x 15 cm)). The CH2C12 solution was washed with water (2 x 10 cm3), dried over Na4SO4 and filtered. Removal of the solvent gave pale yellow solids. Yield: 0.44 g, 55%; m.p. 64~66'C. Found: 75.8; H, 6.6; N, 3.5. Calc. for (C44H44N2P2)" 0.5CH2C12 : C, 75.8 ; H, 6.4; N, 3.5%. IR (KBr) : 3048m, 2912s, 1428s, 1256m, 1086s, 736m, 688m, 488m cm ~. 3~p [IH] NMR (CDCI3): 6 -13 .7 (s) ppm. 'H NMR (CDC13): (~ 6.73 7.46 (28H, m); 3.90 (2H, d, J = 13.8 Hz) ; 3.73 (2H, d, J = 13.5 Hz) ; 2.03 (2H, m); 1.90 (2H, d, J = 12.7 Hz); 1.78 (2H, s, br); 1.51 (2H, m) ; 1.01 (2H, t, J = 9.7 Hz) ; 0.79 (2H, m) ppm. LRMS (FAB: +ve) m/z: 663 ( M + I ) . [~]~o = - 2 9 . 2 3 (c 1, CH:C12).

(iv) lS,2S-evclohexyl-P2N2H4, (S,S)-II. The pro- cedure was similar to that of (R,R)-II. Compound (S,S)-I (0.79 g, 1.21 mmol) and sodium borohy- dride (0.27 g, 7.3 retool) were used. Yield: 0.48 g, 60% ; m.pt 60-62C. Found: C, 77.5; H, 6.6; N, 3.8. Calc. for (C44H44N2P2)"0.3CH2C12: C, 77.3; H, 6.5; N, 4.1%. IR (KBr) : 3048m, 2916, 1430s, 1256m, I084m, 738s, 690m, 490m cm ~. 3up [~H] NMR (CDC13): (3 - 1 3 .7 (s) ppm. IH N MR (CDCI3): 6 6.73 7.46 (28H, m); 3.91 (2H, d, J = 13.8 Hz); 3.73 (2H, d, J = 13.2 Hz); 2.04 (2H, m); 1.91 (2H, d, J = 12.7 Hz); 1.78 (2H, s, br); 1.54 (2H, m); 1.01 (2H, t, J = 9 . 7 Hz); 0.81 (2H, m) ppm. LRMS (FAB: +ve) m/z: 663 ( M + I ) . [~]~0 = 26.63,~ (c 1, CH2C12).

Preparation o/'Cu I complexes

(i) [Cu(lR,2R-o, clohexyI-P2N2)][PF6] (Ilia). A solution of [Cu(CH3CN)4 ] [PF6] (0.32 g, 0.49 retool) and (R,R)-I (0.18 g, 0.49 mmol) in CHzCI 2 (20 cm 3) was stirred at room temperature for 16 h. An orange solution was obtained. The solvent was removed in

Preparation of chiral diimino-

vacuo to give an orange residue. The residue was redissolved in a minimum amount of CH2C12 and chromatographed on a silica gel column (2 x 15 cm) with a 1 : 1 mixture of CH2C12/acetone as eluent to give an orange band. Removal of the solvent from the orange band gave an orange residue which was redissolved in minimum amount of CH2C12. Diethyl ether was added to the CH2C12 solution slowly until it just turned cloudy. The CH2C12/diethyl ether mix- ture was then cooled to - 2 0 C to give orange crys- tals, which were filtered and dried in vacuo. Yield : 0.31 g; 75%, m.p. 208 210"C (decomposed). Found: C, 58.3; H, 4.5; N, 3.0. Calc. for ( C 4 4 H 4 0 N 2 P 3 F 6 C u ) • 0.6CH2C12 : C, 58.3; H, 4.5; N, 3.1%. IR (KBr): 3050m, 2932s, 2880s, 1640s, 1434s, 1094s, 836vs, 744s, 694s, 556m cm-1.31p [~H] NMR (CDCI3) : 6 -0 .3 (br, s) ; - 142.4 (heptet, Jpv = 711.3 Hz) ppm. ~H NMR (CDC13) : 6 8.43 (2H, s); 6.95-7,73 (28H, m); 2.99 (2H, m); 0.95 1.71 (8H, m) ppm. LRMS (FAB: +ve) m/z: 721 (M). [~]~0 = _ 269.08,7 (c 0.5, CHzC12).

(ii) [Cu(1R,2R-cyclohexyl-P2N2)][C104] (lllb). This compound was prepared as described for Illa. [Cu(CH3CN)4][C104] (0.16 g, 0.49 retool) and (R,R)-I (0.32 g, 0.49 mmol) were used. Yield : 0.37 g, 75%, orange crystals, m.p. 238-240' C (decom- posed). IR (KBr): 3052s, 2938s, 2833s, 1649s, 1441s, 1094s, 742s, 695s, 507s cm 1.31p [IH] NMR (CDCI3) : 6 - 1.0 (br, s) ppm. 1H NMR (CDCI3) : 6 8.48 (2H, s) ; 6.92-7.78 (28H, m) ; 3.00 (2H, m) ; 0.95-1.72 (8H, m) ppm. [~]20 = -264.0" (c 0.5, CH2C12).

(iii) [Cu(1S,2S-cyclohexyl-P2N2)][PF6] (IV). This compound was prepared as described for Ilia. [Cu(CH3CN)4][PF6] (0.22 g, 0.61 mmol) and (S,S)- I (0.40 g, 0.61 mmol) were used. Yield : 0.37 g, 70%, orange crystals, m.p. 212-214~C (decomposed). Found: C, 59.2; H, 4.7; N, 2.9. Calc. for (C44H40N2P3F6Cu) • 0.4CH2C12 : C, 59.2 ; H, 4.5 ; N, 3.1%. IR (KBr): 3052m, 2932s, 2860s, 1638s, 1434s, 1094s, 836vs, 746s, 694s, 556m cm 1.3~p [IH] NMR (CDCIs) : 6 -0 .5 (br, s); - 142.5 (heptet, Jp v = 711.3 Hz) ppm. IH NMR (CDCI3) : 6 8.42 (2H, s); 6.94 7.73 (28H, m); 2.99 (2H, m); 1.18-1.71 (8H, m) ppm. LRMS (FAB: +ve) m/z: 721 (M). [c¢]t¢ ~ = 266.87" (c 0.5, CH2C12).

(iv) [Cu(1R,2R-cyclohexyI-P2N2H4)][PF6] (Va). A solution of [Cu(CH3CN)4][PF6] (0.06 g, 0.15 mmol) and (R,R)-II (0.10 g, 0.15 mmol) in CH,CI2 (20 cm 3) was stirred at room temperature for 16 h. A pale blue solution was obtained. The solution was concentrated to ca 5 cm 3. Diethyl ether (5 cm 3) was then added to the solution to effect precipi- tation. The white precipitate was filtered, washed with diethyl ether (2 × 5 cm3), redissolved in a mini- mum amount of CH2C12 and filtered. Diethyl ether

and diaminodiphosphine ligands 4457

was added to the CH2C12 filtrate slowly until it just turned cloudy. The CH2C12/diethyl ether mixture was then cooled to -20°C to give white crystals, which were filtered and dried in vacuo. Yield: 0.10 g, 75%, m.p. 257 259°C (decomposed). Found : C, 59.6; H, 5.1; N, 3.1. Calc. for (C44H44N2P3F6 Cu ) ' H2 0 : C, 59.4; H, 5.2; N, 3.2%. IR (KBr) : 3281s, 3052s, 2938s, 2858s, 1441s, 1098s, 834vs, 755s, 695s, 561s cm -~. 31p [In] NMR (CD2Cl2) : 6 - 5.8 (br, s) ; - 142.4 (heptet, Jp F = 707.3Hz) ppm. ~H NMR (CD2C12) : 6 6.9(~7.50 (28H, m); 3.97 (2H, d of d, J = 13.0 Hz, J = 4.1 Hz); 3.87 (2H, br, d, J = 13.0 Hz); 2.57 (2H, br, s) ;2.38 (2H, m) ; 1.82 (2H, m) ; 1.65 (2H, m) ; 0.91 (4H, m) ppm. LRMS (FAB" +ve) m/z: 725 (M)" [~]~0 = 85.9ff (c 0.5, CH2C12).

(v) [Cu(1R,2R-cyclohexyl-P2N2H4)] [CIO4] (Vb). This compound was prepared as described for Va. [Cu(CH3CN)4][CI04] (0.05 g, 0.15 mmol) and (R,R)-II (0.10 g, 0.15 mmol) were used. Yield: 0.09 g, 70%, white crystals, m.p. 270-272°C (decom- posed). IR (KBr): 3281s, 3052s, 2918s, 2851s, 1447s, 1091vs, 755s, 695s, 514scm t. 3~p [LH] NMR (CD2C12) : ~ -6 .0 (br, s) ppm. IH NMR (CD2C12) : 6 6.96-7.50 (28H, m); 3.97 (2H, d of d, J = 13.0 Hz, J = 4.1 Hz) ; 3.87 (2H, br, s, J = 13.0 Hz) ; 2.57 (2H, br, s) ; 2.36 (2H, m) ; 1.82 (2H, m) ; 1.65 (2H, m); 0.91 (4H, m) ppm. [~]~0 = 84.35 (c 0.5, CH2C12).

(vi) [Cu(1S,2S-cyclohexyl-P4N2H4)][PF6] (VI). This compound was prepared as described for Va. [Cu(CH3CN)4][PF6] (0.06 g, 0.15 mmol) and (S,S)- II (0.10 g, 0.15 mmol) were used. Yield: 0.09 g, 70%, white crystals, m.p. 259-261°C (decom- posed). Found: C, 60.2; H, 5.1 ; N, 3.2. Calc. for C44H44N2P3F6Cu: C, 60.6; H, 5.1: N, 3.2%. IR (KBr) : 3288m, 3056m, 2928s, 1434s, 1092s, 828vs, 740s, 692s, 510m cm -~. 3!p [1H] NMR (CD2C12) : t~ -6.1 (br, s); -142.3 (heptet, Jp_~ = 707.3 Hz) ppm. ~H NMR (CD2CI2): ~ 7.04~7.58 (28H, m); 4.05 (2H, d of d, J = 13.2 Hz, J = 3.8 Hz): 3.95 (2H, d, J = 13.2 Hz); 2.63 (2H, br, s); 2.46 (2H, m) ; 1.91 (2H, m) ; 1.73 (2H, m) ; 0.99 (4H, m) ppm. LRMS (FAB" +ve) m/z: 725 (M). [~]~0= -86.35 '~ (c 0.5, CH2C12).

Preparation of Ag ~ complexes

(i) [Ag(1R,2R-cyclohexyl-PzNz)][BF4] (VII). A solution of AgBF4 (0.12 g, 0.61 mmol) and (R,R)- I (0.40 g, 0.61 mmol) in CH2CI 2 (20 cm 3) was stirred at room temperature for 24 h. A yellow solution was obtained. The solvent was removed in vacuo to give a yellow residue. The residue was redissolved in a minimum amount of CH2C12 and chro-

4458 WAI-KWOK WONG et al.

matographed on a silica gel column (2 × 15 cm) with a 1 : 1 mixture of CH2C12 : acetone as eluent to give a yellow band. Removal of the solvent from the yellow band gave a yellow residue, which was redissolved in minimum amount ofCHzC12. Hexane was added to the CH2C12 solution slowly until it just turned cloudy. The CH2C12/hexane mixture was then cooled to -20°C to give light yellow crystals, which were filtered and dried in vacuo. Yield : 0.41 g ; 70%, m.p. 222-224°C (decomposed). Found : C, 61.6; H, 4.9; N, 3.1. Calc. for C44H40NzP2F4BAg : C, 61.9 ; H, 4.7 ; N, 3.3%. IR (KBr) : 3052m, 2928s, 2852s, 1632vs, 1434s, 1056vs, 746s, 694s, 504m cm 1. 31p [iH] NMR (CDC13): 6 11.3 (d, Jp p = 40.6 Hz); 16.2 (d, Jp p = 40.6 Hz) ppm. 'H NMR (CDCI3) : 6 8.48 (2H, s) ; 7.83 (2H, m) ; 7.19-7.60 (24H, m); 6.80 (2H, m); 3.34 (2H, m); 1.50 (2H, m); 1.30 (2H, m); 1.04 (2H, m); 0.76 (2H, m) ppm. LRMS (FAB: +ve) m/z: 765 (M). [cc]~) ° = -51.15 ° (c 0.5, CH2C12).

(ii) [Ag(1S,2S-eyclohexyl-P2N2) ] [BF4] (VIII). This compound was prepared as described for VII. AgBF4 (0.12 g, 0.61 mmol) and (S,S)-I (0.40 g, 0.61 mmol) were used. Yield : 0.44 g, 75%, light yellow crystals, m.p. 218-220°C (decomposed). Found : C, 62.1 ; H, 4.9; N, 3.2. Calc. for C44H40N2P2F4BAg : C, 61.9 ; H, 4.7 ; N, 3.3%. IR (KBr) : 3052m, 2924s, 1626s, 1430s, 1056vs, 742s, 688s, 496m cm -~. 3Jp ['H] NMR (CDCI3) : di 10.5 (d, Jp_p = 36.6 Hz) ; 15.3 (d, Jp p = 36.6 Hz) ppm. IH NMR (CDCI3) : 6 8.52 (2H, s) ; 7.80 (2H, m) ; 7.20-7.66 (24H, m) ; 7.05 (2H, m); 3.08 (2H, m); 2.46 (2H, m); 1.80 (2H, m); 1.04 (4H, m) ppm. LRMS (FAB: +ve) m/z: 765 (M). [~]~0 = 61.86 c~ (c 0.5, CH2C12).

(iii) [Ag(lR,2R-cyclohexyl-P2N2H4)][BF4] (IX). This compound was prepared as described for VII. AgBF4 (0.11 g, 0.47 mmol) and (R,R)-II (0.31 g, 0.47 mmol) were used. Yield: 0.30 g, 70%, white crystals, m.p. 247 249°C (decomposed). Found: C, 61.1; H, 5.3; N, 3.0. Calc. for (C44H44N2P2F4 BAg)'0.5H20: C, 61.0; H, 5.2; N, 3.2%. IR (KBr): 3288s, 3059s, 2932s, 2858s, 1441s, 1085vs, 755s, 702s, 520s cm- ' . 31p [1H] NMR (CDC13) : 6 - 0 . 4 (d, J p _ p = 28.5 Hz) ; 3.5 (d, J p p = 28.5 Hz) ppm. 1H NMR (CDC13): 6 7.11-7.40 (26H, m); 6.80 (2H, m); 3.91 (2H, m); 3.72 (2H, m); 2.37 (2H, s, br) ; 2.22 (2H, m) ; 2.00 (2H, m) ; 1.64 (2H, m); 1.04 (4H, m) ppm. LRMS (FAB: +ve) m/z: 769 (M). [~]~)o = 42.80 ° (c 0.5, CHzC12).

(iv) [Ag(l S,2S-cyclohexyl-P2N2H4)] [BF4] (X). This compound was prepared as described for VII. AgBF4 (0.11 g, 0.47 mmol) and (S,S)-II (0.31 g, 0.47 mmol) were used. Yield: 0.29 g, 65%, white crystals, m.p. 250-252°C (decomposed). Found : C, 60.9; H, 5.2; N, 3.0. Calc. for (C44H44N2P2F4

BAg)-0.5H20: C, 61.0; H, 5.2; N, 3.2%. IR

(KBr) : 3301s, 3052s, 2932s, 2851s, 1447s, 1085vs, 742s, 695s, 514s cm -1. 31p [1HI NMR (CDCI3) : 6 0.4 (d, Jp p = 2 8 .5 Hz) ;4 .2 (d, Jp p = 2 8 . 5 H z ) ppm. 1H NMR (CDC13): 6 7.13-7.37 (26H, m); 6.83 (2H, m); 3.90 (2H, m); 3.76 (2H, m); 2.39 (2H, s, br) ; 2.22 (2H, m) ; 2.00 (2H, m) ; 1.64 (2H, m); 1.04 (4H, m) ppm. LRMS (FAB: +ve) re~z: 769 (M). [c~] 2° = -43.18 ° (c 0.5, CH2C12).

X-ray diffraction studies

(i) Crystals of IV suitable for X-ray diffraction study were grown by slow diffusion of diethyl ether into a saturated solution of IV in CH2C12 as a solv- ate of stoichiometry (IV)2"CH2C12" (C2H5)20. An orange crystal of dimensions 0.30 x 0.50 × 0.40 mm 3 was mounted on a glass fibre with epoxy resin. Intensity data were collected on a Siemens P4/Ra diffractometer at 203 K, using graphite-mon- ochromated Cu-K~ radiation (2 = 1.54178 •). A total of 5843 unique reflections (3 ~< 20 ~< 110 °) were measured; 5534 of these had I ~> 4or(/) and were considered to be observed. The data were cor- rected for Lorentz and polarization factors and semi-empirical absorption was applied. Crystal data, data collection parameters and results of the analysis are given in Table 3. The structure was solved by direct methods and refined by full-matrix least-squares analysis, with all non-hydrogen atoms assigned anisotropic displacement parameters. Hydrogen atoms were generated in their idealized positions (C--H bond fixed at 0.96 A) and allowed to ride on their respective parent carbon atoms. These hydrogen atoms were assigned appropriate isotropic thermal parameters and included in the structure factor calculations but not in the refine- ment. Computations were performed using the SHELTXL-PLUS program package. 8 The absolute configuration of the original ligand (1S,2S) has been checked by refinement based on the anom- alous dispersion of the Cu, F and P atoms.

(ii) Crystals of IX suitable for X-ray diffraction study were grown by slow diffusion of diethyl ether into a saturated solution of IX in CHzC1 z as a solv- ate of stoichiometry IX" CH2C12. A colourless prism of dimensions 0.25 x 0.25 x 0.42 mm 3 was mounted on a glass fibre with epoxy resin. Intensity data were collected on a Siemens R3m/V diffractometer at 294 K, using graphite-monochromated Mo-K~ radi- ation (2 = 0.71073 ~). A total of 4141 unique reflections (7 ~< 20 ~< 45 °) were measured; 2304 of these had I >~ 4~r(/) and were considered to be observed. The data were corrected for Lorentz and polarization factors and semi-empirical absorption correction was applied. Crystal data, data col-

Preparation of chiral diimino- and diaminodiphosphine ligands 4459

Table 3. Data collection and processing parameters for IV and IX

IV IX

Empirical formula Colour, habit Crystal size (mm) Crystal system Space group Unit cells dimensions

Volume (/k 3) Z Formula weight Density (calc.) (g cm -3) Absorption coefficient (cm -~) F(000) Diffractometer Radiation Temperature (K) 20 range C) Scan type Scan rate C min ~ in ~o) Scan range (co) (o) Background measurement

Standard reflections Index ranges

Reflections collected Independent reflections Observed reflections Absorption correction Refinement program Solution methods Refinement method Quantity minimized Weighting scheme R indices (observed data) Goodness-of-fit Largest A/o Number of parameters, p Residual extrema (e A --3)

C 9 3 H 9 2 N 4 P 6 F I / C u 2 C 1 2 0

Orange prism 0.30 x 0.50 x 0.40 Monoclinic P2t a = 10.893(2) A b = 30.117(2) A c = 14.603(2) A /J = 110.95(2) ° 4473.3(11) 2 1893.5 1.406 27.76 1952 Siemens P4/RA Cu-K~ (2 = 1.54178 A) 203 3.0-110.0 0~-20 Variable, 6.00-60.00 0.90 Stationary crystals and stationary counter at beginning and end of scan, each for 25.0% of total scan time 3 measured every 150 reflections 0~<h~< 1 1 ; 0 ~ < k ~ 3 2 ; - 1 5 ~<l~ 14 5843 5731 (Rint = 3.56%) 5534 (Io > 4.0a(Io)] Semi-empirical SHELXTL-PLUS (UNIX) Direct methods Full-matrix least-square Zw(Fo- Fc) 2 w-I = a2(F) + 0.0005F 2 R = 0.043 ; wR = 0.058 2.05 0.02 1092 0.64 to -0 .63

C45H46N2PzF4AgCl:B Colourless prism 0.25 × 0.25 × 0,42 Orthorhombic P212121 a = 9.333(9) A b = 20.881(5) A c = 22.645(4) A

4413(4) 4 941.7 1.415 7.01 1920 Siemens R3m/V Mo-K~ (2 = 0.71073 A) 294 7.0-45.0 o~20 Variable, 6.00-60.00 0.60 Stationary crystals and stationary counter at beginning and end of scan, each for 0.5% of total scan time 3 measured every 97 reflections 0~<h~<9;0~<k~<24; 0 ~ / ~ 2 6 4141 4141 (R~nt = 0.00%) 2304 (Io > 4.0a(Io)] Semi-empirical SHELXTL-PLUS (PC) Direct methods Full-matrix least-square Ew(Fo- Fc) 2 W I = o . 2 ( F ) 4 _ 0 . 0 0 0 5 F 2

R = 0.065 ; wR = 0.062 1.29 0.002 537 0.70 to --0.95

4460 WAI-KWOK WONG et al.

lection parameters and results of the analysis are given in Table 3. The structure was solved by direct methods and refined by full matrix least-squares analysis, with all non-hydrogen atoms assigned anisotropic displacement parameters. Hydrogen atoms were generated in their idealized positions ( C - - H bond fixed at 0.96 A,) and allowed to ride on their respective parent carbon atoms. These hydrogen atoms were assigned appropriate iso- tropic thermal parameters and included in the struc- ture factor calculations, but not in the refinement. Computat ions were performed using the SHELTXL-PLUS program package. ~ The absolute configuration of the original ligand (1R,2R) has been checked by refinement based on the anom- alous dispersion of the Ag, F and P atoms.

Aeknowledgements--W.-K.W. thanks the Hong Kong Baptist University and the Hong Kong Research Grant Council for financial support.

REFERENCES

I. W. K. Wong, J.-X. Gao, Z.-Y. Zhou and T. C. W. Mak, Polyhedron 1992, 11, 2965.

2. W. K. Wong, J.-X. Gao and W. T. Wong, Polyhedron 1993, 12, 1647.

3. W. K. Wong, J.-X. Gao, Z.-Y. Zhou and T. C. W. Mak, Polyhedron 1993, 12, 1415.

4. W. K. Wong, J.-X. Gao, W. T. Wong, W. C. Cheng and C. M. Che, J. Oryanomet. Chem. 1994, 471,277.

5. J.-X. Gao, H.-L. Wan, W. K. Wong, M. C. Tse and W. T. Wong, Polyhedron 1996, 15, 1241.

6. J. C. Jeffrey, T. B. Rauchfuss and P. A. Tucker, Inor 9. Chem. 1980, 19, 3306.

7. J. F. Larrow and E. N. Jacobsen, J. Org. Chem. 1994, 59, 1939.

8. G. M. Sheldrick, Crystallographic Computin 9 3 : Data Collection, Structure Determination, Proteins, and Dat- abases (edited by G. M. Sheldrick, C. Kruger and R. Goddard), p. 175. Oxford University Press, New York (1985).