Trinuclear osmium clusters containing bidentate Ph2PCH2PPh2 and Me2PCH2PMe2 ligands: X-ray crystal structures of the complexes [Os3H(CO)9(Me2PCHPMe2)] and [Os3H(OH)(CO)8(Ph2PCH2PPh2)

Abstract

The clusters [Os3(CO)10(dppm)](dppm = Ph2PCH2PPh2) and [Os3(CO)10(dmpm)](dmpm = Me2PCH2PMe2) react with trimethylamine N-oxide in acetonitrile solution to give [Os3 CO)9-(dppm)(MeCN)](1) and [Os3(CO)9(dmpm)(MeCN)](2) respectively. The acetonitrile ligand of (1) and (2) is readily displaced by other two-electron donor ligands to give [Os3(CO)9(dppm)L][L = PPh3, P(OMe)3, or ButNC] and [Os3(CO)9(dmpm)L][L = P(OMe)3 or C2H4]. Thermolysis of [Os3(CO)9(dmpm)(C2H4)] or [Os3(CO)10(dmpm)] gives the cyclometallated product [Os3H (CO)9-(Me2PCHPMe2)]. The acetonitrile complex (1) also reacts with HX (X = Cl or SR, R = alkyl) to give clusters of general formula [Os3H(X)(CO)8(dppm)], whereas for X = OH or OMe the only product isolated is [Os3H(CO)8{Ph2PCH2PPh(C6H4)}]. The dmpm derivative (2) reacts similarly with HCl and RSH. The cluster [Os3H(OH)(CO)8(dppm)], which can be prepared from [Os2H-(OH)(CO)10] and dppm, was found to have a different structure from [Os3H(Cl)(CO)8(dppm)]. All the products were characterised by i.r. and n.m.r. spectroscopy. The structures of [Os3H(CO)9-(Me2PCHPMe2)] and [Os3H(OH)(CO)8(dppm)] were confirmed by X-ray crystallography.