Preparation, structural studies, and some reactions of new heterobinuclear complexes containing molybdenum, tungsten, or manganese and rhodium or copper; X-ray crystal structures of [MoRh(CO)(μ-CO)2(PPh3) 2(η-C5H5)] and two isomers of [CuW(CO) 3(PPh3)2(η-C5H5)]

Laurence Carlton, W. Edward Lindsell, Kevin J. McCullough, Peter N. Preston

Research output: Contribution to journalArticle

Abstract

Reaction of the anions [M(CO)3(?-C5H 5)]- or [Mn(CO)5]- with [RhCl(PPh3)3] in tetrahydrofuran produces the formally unsaturated bimetallic complexes [MRh(CO)(µ-CO)2(PPh 3)2(?-C5H5)] [M = Mo (1) or W (2)] or [MnRh(CO)2(µ-CO)2(PPh3)3] (3) respectively. An X-ray diffraction study of (1) has established its molecular structure: monoclinic, space group P21/c, a = 18.102(2), b = 10.407(1), c = 20.736(2) Å, ß = 104.99(1)°, and Z = 4. The structure, determined from 5 233 independent intensities, was refined to R = 0.036 (R1 = 0.074). It comprises a Mo(CO)(?-C5H 5) group bonded to Rh(PPh3)2 with a short Mo-Rh separation 2.588(1) Å and two asymmetric (µ-CO) ligands with Mo-C 1.980(6) and 2.026(5) Å and Rh-C 2.182(6) and 2.092(5) Å; the Mo(µ-CO)2Rh framework has a dihedral angle (Mo-Rh-C/Mo-Rh-C) of 161°. I.r., 1H and 31P-{1H} n.m.r. spectra of complexes (1)-(3) are presented and discussed in relation to their structures: formal metal-metal multiple bonds, Rh-?M, are proposed. Complex (1) acts as a catalyst in hydrogenation of cyclohexene and reactions involving the cleavage of M-Rh bonds are described for complexes (1) and (3). Reactions of [M(CO)3(?-C5H5)]- with [{CuCl(PPh3)}4] give the bimetallic products [CuM(CO)3-(PPh3)2(?-C5H 5)] [M = Mo (4) or W (5)] in relatively low yields. Complex (5) has been obtained in two isomeric crystalline forms, (5a) and (5b), for which X-ray crystal structure determinations have been undertaken: (5a), triclinic, space group P1 (no. 2), a = 12.404(4), b = 11.756(3), c = 14.208(3) Å, a = 101.4(2), ß = 79.5(2), ? = 110.3(2)°, and Z = 2; (5b), monoclinic, space group P21/c (no. 14), a = 17.991 (3), b = 10.098(2), c = 21.608(2) Å, ß = 105.66(1)°, with Z = 4. The structures of (5a) and (5b) have been refined to residuals R = 0.058 and 0.034 from 3 997 and 4 009 unique reflections, respectively. Both isomers contain W(CO)3(?-C5H5) groups bonded to Cu(PPh 3)2 units. The carbonyl ligands are essentially terminally bound to W but two CO groups show some semibridging interactions with Cu, especially in structure (5b); Cu-C 2.309(13) and 2.405(13) Å in (5a), 2.260(8) and 2.197(9) Å in (5b). In (5a) the Cu(PPh3) 2 unit occupies the position typical of a ligand to W in a complex with 'four-legged piano stool' geometry [W-Cu 2.721(1) Å; dihedral angle (W-Cu-C/W-Cu-C') 139.8°]. In (5b) the W(µ-CO)2Cu fragment is almost planar (W-Cu-C/W-Cu-C' 170.9°) and W-Cu [2.771 (1) Å] is longer. The structures and bonding of complexes (4) and (5) are discussed in relation to i.r. and n.m.r. spectral data; in solution, 13C-{1H} n.m.r. spectra support a non-rigid structure for complex (5).

Original languageEnglish
Pages (from-to)1693-1701
Number of pages9
JournalJournal of the Chemical Society, Dalton Transactions
Issue number8
DOIs
Publication statusPublished - 1984

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