Dirhodium(II,II) tetra-acetate complexes with sulphur donors. The crystal structure of [Rh 2(O 2CMe) 4(L) 2] (L = N, N-dimethylthioformamide or N, N-dimethyl O-ethylthiocarbamate)

Abstract

The rhodium(II) complexes [Rh 2(O 2CMe) 4(DMTC)] and [Rh 2(O 2CMe) 4(L) 2], where L = DMTC (EtOSCNMe 2), DMTA (MeSCNMe 2), DMTF (HSCNME 2), TBA (PhSCNH 2) and TAA (MeSCNHPh), have been prepared and characterized by infrared, 1H NMR and electronic spectroscopy. The structures of [Rh 2(O 2CMe) 4(DMTC) 2] ( I) and [Rh 2(O 2CMe) 4(DMTF) 2] ( II) were determined by X-ray crystallography. Compound I is monoclinic, space group P2 1/ n, with a = 15.665(5), b = 8.184(5) and c = 21.976(5) Å, and β = 106.76(3)°; D c = 1.74 g cm −3 for Z = 4. The structure was refined to R = 0.048 for 2385 observed reflections. Compound II is triclinic, space group P 1 , with a = 9.503(5), b = 8.206(5), c = 8.123(5) Å, α = 114.65(3)°, β = 105.21(3)° and γ = 90.60(3)°; D c = 1.87 g cm −3 for one formula unit per unit cell. The structure was refined to R = 0.030 for 2445 observed reflections. Both compounds are binuclear complexes where two rhodium atoms, linked by four bridging acetato groups, form a strong direct metalmetal bond. The RhRh distances are 2.409(1) Å in I and 2.418(1) Å in II. The strong trans influence of the RhRh bond is reflected the weakness of the axial RhS bond (2.624 Å in I and 2.546(1) Å in II). Structural details of the dirhodium(II) tetraacetato moieties are fully equivalent in the two compounds. The colour of the complexes (green ( I) and violet ( II)) seems to depend on the RhS bond strength.