Studies on homogeneous and immobilized metal carbonyl clusters on inorganic oxide

A detailed investigation of the reaction between Os3(C))12 and Ru3(CO)12 with HOR (R = CH3, SiPh3), HOOCR (R = H, CH3) and 2,4-pentanedione was undertaken and the products of the form (μ-H)M_3(CO)_10(L) and [ M_3(CO)_10L^-] were characterized by i.r. and n.m.r. spectroscopies. The substitution of (μ-H)Os3(CO)10(O2CCH3) with phosphines is studied and the resulting cluster compounds(μ-H)Os_3(CO)_9(O_2CCH_3)(PPh_3) isolated and characterized by i.r. and n.m.r. spectroscopies. Infrared and raman spectroscopic studies of triosmium and triruthenium hydride carbonyl clusters were carried out to determine the hydrogen vibrational frequencies. The hydride modes of vibration in (μ-H)2M3(CO)10, (μ-H)_2M_3(CO)_9(E), (E = S, PPh) and (μ-H) (μ-E')Os_3(CO)_10 (E' = OR, O_2CR and acac) clusters were compared and the ability to identify particular co-ordination modes of hydrogen established. The immobilization of metal carbonyl clusters onto inorganic oxide and phosphine functionalized supports was investigated by i.r. and solid state magic angle spinning n.m.r. The triosmium and triruthenium carbonyls were shown to react with silica and alumina to form [(μ-H)M3(CO)_10-O O-silica/alumina] or [(μ-H)M3(CO)10-O-silica/alumina] in mild conditions. The reaction of Os3(CO)11(L) and H20s3(CO)10(L) (L =PPh2(CH)2Si(OEt)3) with silica was shown to give intact supported species, while a surface attached cluster (μ-H)Os_3(CO)9(L)break (O O-silica) is proposed to result in the case of (μ-H)_2Os_3(CO)_9(L). The rhodium carbonyls Rh4(CO)_11(L) and Rh6(CO)_15(L) were found to form initially [ Rh_4(CO)_11(L')] and Rh_6(CO)_15(L') (L' = PPh_2(CH_2)_2Si-(OEt)_3-x(OSi≡)x) which decompose on exposure to air to a common surface containing L'Rh(I)(O)2and Rh(I)(CO2)2. The direct interaction of Rh4(CO)12 and RH6(CO)16, at room temperature, with phosphinated silica was shown to result in initial formation of Rh (CO)12-x(L')x' x = 1,2 and complex surface, containing Rh6(CO)16-x(L')x x = 1, LRh(I)(CO)2, Rh(I)(CO)2fragments and CO covered metallic rhodium. (D74035/87)