f’olyhedron Vol. 12, No. II, pp. 141~1417, 1993 Printed in Great Britain

0277-53X7/93 $6.00+.00 0 1993 Pergamon Press Ltd

COMMUNICATION

SYNTHESIS AND CHARACTERIZATION OF RUTHENIUM DIIMINODIPHOSPHINE COMPLEXES. X-RAY STRUCTURE

OF TRANS-Ru(P,N,)CI, .2H,O (P2N2 = N,N’-BIS (o-(DIPHENYLPHOSPHINO)BENZYLIDENE]ETHYLENEDIAMINE)

WAI-KWOK WONG*

Department of Chemistry, Hong Kong Baptist College, Kowloon, Hong Kong

and

JING-XING GAO

Department of Chemistry, Xiamen University, Xiamen 361005, Fujian, P.R.C.

and

ZHONG-YUAN ZHOU and THOMAS C. W. MAK*

Department of Chemistry, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong

(Received 22 February 1993 ; accepted 4 March 1993)

Abstract-The interaction of Ru(OAc)2(Ph3P)2 with 1 equivalent of N,N’-bis[o-(diphenyl- phosphino)benzylidene]ethylenediamine (P2N2) in refluxing dichloromethane gives trans- Ru(OAC)~(P~NJ (I) in moderate yield (63%) ; in refluxing toluene the reaction gives a red product, which upon recrystallization in CHCl,/hexane gives trans-Ru(OAC)~C~~ - 2H20 (III) in good yield (92%). Compounds I and III have been fully characterized by analytical and spectroscopic methods. The structure of III has been determined by an X-ray diffraction study.

Ru(OAc)2(Ph3P)Z is a very versatile reagent. It pro- vides a very good entry to ruthenium(I1) complexes. Since its preparation a large number of ruthenium carboxylate complexes have been synthesized, and most of the known mononuclear acetates are Ph3P complexes. Recently, ruthenium diphosphine and triphosphine complexes have been synthesized. 1*2 Ruthenium acetate complexes have been shown to display various catalytic properties, 3 particularly those with chiral chelating diphosphine ligands. 4 Chelating multidentate phosphine ligands offer several advantages over monodentate phosphines containing similar phosphino groups. They can pro-

* Authors to whom correspondence should be addressed.

vide better control over the coordination number and stereochemistry of the resulting complexes, increase basicity at the metal centres and slow down intra- and intermolecular exchange processes. ’ N,N’ - bis[o - (diphenylphosphino)benzylidene]ethyl- enediamine (P2N2), a polydentate ligand, can serve as a bi-, tri- and tetradentate ligand depending on the reaction conditions.“’ It is likely that a ruthenium acetate complex containing the P2N2 ligand may display some interesting structural, chemical and catalytic properties that are not ob- served in other chelating phosphine complexes. In this communication the interaction of Ru(OAC)~ (Ph,P), with the polydentate diiminodiphosphine ligand P2N, is reported.

When Ru(OAc)2(Ph3P)2 was treated with 1 equi-

1415

1416 Communication

valent of P,N2 in refluxing dichloromethane for 16 h, work-up gave red crystals of the stoichiometry [Ru(PzN2)(CH3C00),] * 2H20 (I)* in moderate yield (63%) after recrystallization from an ace- tone/Et,0 mixture. Compound I exhibits absorp- tions at 1562~s and 1380s cm- 1 in the IR spectrum and a singlet at 6 1.06 ppm ib the ‘H NMR spectrum for the acetate groups. The p ‘P{ ‘H} NMR spectrum of I exhibits a singlet at 6

“d”

.6 ppm, indicating that the two phosphino group of the P2N2 ligand are

* Ru(CH,COO)~(C~,,H~~N~PJ*~H~O: red crystals, m.p. 216219°C (dec.). Found: C, 61.3; H, 4.8; N, 3.1. Calc.: C, 61.5; H, 5.1; N, 38.3%. IR (cm-‘, in KBr): 34OOs, 3048w, 1608s, 1582~6, 1562vs, 1478w, 143Os, 138Os, 1326w, 1264w, 1182q, 1138w, 1090m, 102Ow, 74Om, 684m, 508m, 458m. f’P{‘H} NMR (CDCI,): 6 48.6(s) ppm. ‘H NMR (C&l,): olefinic protons, 6 8.97 (2H, m); phenyl protoqs, 6 6.80-7.53 (28H, m); NCH,CHIN protons, 6 4.59 ;(4H, s) ; water protons, 6 1.69 (4H, s) ; acetate methyl p$otons, 6 1.07 (6H, s) ppm.

t RuC12(C,,H,,N,P,) * 2H,/O : dark red crystals, m.p. 168-171°C(dec).Found:C,59.3;H,4.5;N,3.3;Cl,9.0. Calc.: C, 59.1; H, 4.7; N, $4; Cl, 8.7%. IR (cm-‘, in KBr): 3476br, 3044m, 2916w, 1628m, 1478m, 1428s, 1344w, 1298m, 1264m, 1216C, 1186w, 1156w, 1134w, 1088m, 74Os, 686vs, 476m. T’P{‘H) NMR (CDCI,): 6 46.1 ppm. ‘H NMR (CdCl,): olefinic protons, 6 8.99 (2H, m); phenyl protofls, 6 6.8&7.60 (28H, m); NCH,CH2N protons, 6 4.33 (4H, s) ; water protons, 6 1.53 (4H, s) ppm.

$Crystal data for (C,,H3

!Y

2P2)RuCl,*2H,0: mol. wt 812.71, monoclinic, spa group C2/c (No. 15), a = 38.751(15), b = 10.299 4), c = 25.377(9) A, /? = 123.13(13)“, U = 8479.9(d) h;‘, Z = 8, Dcalc = 1.27 g cnm3, F(OOO) = 3328, MO-K, badiation (1 = 0.71073 A), p = 6.02 cm- ‘. Data were collected to 2&,,, = 59” using a crystal (0.24 x 0.36 x 0.35 mm) on a Siemens P4 diffrac- tometer in the variable w-scab mode and corrected for absorption (pr = 0.20, tra*mission factors 0.834- 0.975) ; 7991 unique reflectibns, of which 4493 with IF,1 2 6S(lFJ) were employed In structure analysis using the SHELXTL-PC program! system. Other than the four independent water oxy@ atoms which exhibit half site occupancy, all nqn-hydrogen atoms were subjected to anisotropic refinhent. All hydrogen atoms, except those of the disorderbd water molecules, were placed in their idealized posit@ with assigned isotropic thermal parameters and included in structure-factor calculations. The weighti$g scheme used was w = [0*(I~~l)+O.O003lr;,l’]- ’ rjnd the final residuals were R = 0.062 and R' = 0.074. i Atomic coordinates are available from the Director of the Cambridge Crystallographic Data Cen rt, University Chemical Laboratory, Lensfield Road 1 Cambridge CB2 IEW, U.K. Any request should bi: accompanied by a full literature citation for this conimunication.

coordinated and equivalent. The IR and ‘H NMR data indicate that the two acetate groups are mono- dentate and equivalent. This rules out the salt for- mulation [Ru(O,CCH,)(P,N,)][CH,CO,]. There are two possible isomers for I. These are the cis- and trans-isomers, as shown below.

F-P ?Ac

Cis Trans

The available spectroscopic data cannot distinguish between the two isomers. However, since the cor- responding chloro complex, Ru(P2N2)C12, adopts a trans-configuration (via inpa), a trans-con- figuration is assigned to I.

When the above reaction was performed in refluxing toluene for 16 h, work-up gave a red solid (II), whose IR and ‘H NMR spectra showed the absence of the acetate groups. Compound II has a very complex ‘H NMR spectrum ; however, its 3’P{‘H} NMR spectrum exhibits only a singlet at 6 3.8 ppm. Attempts to obtain an analytically pure sample of II for analysis were unsuccessful. When II was recrystallized from a CHClJhexane mixture, dark red crystals of stoichiometry Ru(P2NJCl,* 2H,O (III)? were obtained in high yield (92%). This showed that II reacted with chloroform to give III and the chloro ligands of III originated from chloroform. The IR and ‘H NMR spectra of III do not exhibit any absorption due to acetate groups. The ‘H NMR spectrum of III exhibits resonances due to the P2N2 alone, whereas a resonance due to the methyl protons of acetate is not observed. 3’P( ‘H} NMR of III exhibits a singlet at 6 46.1 ppm, indicating that the two phosphino groups of the PzNz ligand are coordinated and equi- valent. Since the available spectroscopic data again cannot be used to distinguish between the cis- and trans-isomers of III, an X-ray diffraction studyi was performed to establish the structure unequi- vocally. A perspective drawing and selected bond lengths and angles of III are shown in Fig. 1 and its caption. All bond lengths and angles are normal.

The solid state structure of III reveals a trans- configuration for the complex. The structure shows that the two chloro ligands are mutually tram to each other and the P2N, ligand acts as a tetra- dentate ligand with the two phosphino groups cis to each other.

Communication 1417

Acknowledgements-Financial support from the Hong Kong Baptist College and the UPGC (Hong Kong) is gratefully acknowledged.

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