Syntheses, structures and spectroscopic properties of a novel series of metal-metal bonded complexes Ru(E)(E')(CO)(2)(Pr-i-DAB):(E=Br, E'=Mn(CO)(5); E=SnPh3, E'=Mn(CO)(5), Re(CO)(5), Co(CO)(4); E=Me, E'=Re(CO)(5); E=E'=Mn(CO)(5), Re(CO)(5); Pr-i-DAB=N,N'-diisopropyl-1,4-diaza-1,3-butadiene)

This article describes the syntheses, structures and spectroscopic (IR, Raman, NMR, visible absorption) properties of novel metal-metal bonded complexes of the type trans, cis-Ru(E)(E')(CO)(2)(Pr-i-DAB) in which E = Br, Me, SnPh3, Mn(CO)(5) or Re(CO)(5) and E' = Mn(CO)(5), Re(CO)(5) or Co(CO)(4) (depending on E). The structures of Ru(SnPh3)(Mn(CO)(5))(CO)(2)(Pr-i-DAB) Ru(SnPh3)(Co(CO)(4))(CO)(2)(Pr-i-DAB) and Ru(Re(CO)(5))(2)(CO)(2)(Pr-i-DAB) were determined by single crystal X-ray diffraction. The complexes have a distorted octahedral geometry with E and E' in axial positions. The structure of Ru(SnPh3)(Co(CO)(4))(CO)(2)(Pr-i-DAB) is noteworthy, since one of the carbonyl ligands of the Co(CO)(4) group forms a semi-bridge with Ru. The IR and Raman spectra in the nu(CO) and nu(5)(CN) wavenumber region are assigned. The absorption spectra show one or two charge-transfer bands in the visible region, their position and number depending on E and E'. The SnPh3-complexes show in the H-1 NMR spectra a large (4)J(Sn-117/119,H) coupling constant for the imine protons of their Pr-i-DAB ligands, which points to a strong delocalisation of charge within these complexes.