Synthetic, spectroscopic and electrochemical characterisation of mixed-metal acetylide complexes

Terminal metal acetylide complexes trans-[(dppm),(Cl)Os(-C=C-R-C=C-H)] (dppm = Ph2PCH2PPh2, R = -p-C6H4- (1), -p-C6H4-C6H4-p- (2)) and trans-[(Et3P)(2)(Ph)Pt(C=C-p -C6H4-C=CH)] (3) have been synthesised by the application of established synthetic routes. Acetylide bridged mixed-metal complexes trans-[(dppm)(2)(Cl)Os-C=C-p-C6H4-C=C-Ru(Cl)(dppm)(2)] (4), trans-[(Et3P)(2)(Ph)Pt- C=C-p-C6H4-C=C-Ru(Cl)(dppm)(2)] (5), trans-[(Et3P)(2)(Ph)Pt-C=C-p-C6H4-C=C-Ru(Ph3P)(2)(eta(5)-C5H5)] (6) and trans-[(Et3P)(2)(Ph)Pt-C=C-p-C6H4-C=C-Ru(Ph3P)(2)(eta(5)-C5H4-CH3)] (7) have been formed by the reaction of 1, 2 and 3 with the appropriate metal chlorides. Complex 6 is less soluble in common organic solvents than the other complexes but this insolubility has been overcome by introducing a methylcyclopentadienyl group on the ruthenium centre to form complex 7. Complexes 1, 2, 4, 6 and 7 have shown reversible redox chemistry and in the di-metallic complexes, intramolecular electronic communication has been investigated by cyclic voltammetry. The shift in the lowest energy band in the UV-vis spectra of the mixed-metal complexes 4, 5, 6 and 7 is largely dependent on the various metal fragments. (C) 1998 Elsevier Science S.A. All rights reserved.