Synthesis and reactivity of early-late heterodinuclear complexes stabilized by a trisilylsilane-based tripodal amido ligand

The reaction of the complexes [MeSi{SiMe2N(R)}(3)MX] (R = p-tolyl, 2-FC6H4; M = Ti, Zr, Hf; X = Cl, Br) with K[CpM'(CO)(2)] afforded the metal-metal b onded heterodinuclear complexes [MeSi{SiMe2N(R)}(3)M-M'(CO)(2)Cp] (M = Ti, Zr, Hf; M' = Fe, Ru; R = p-tolyl, 2-C6H4), all of which are thermally stabl e in the solid state and in solution. X-ray crystal structure analyses of t he complexes [MeSi{SiMe2N(p-tol)}(3)M-M'(CO)(2)Cp] (M. M': Ti, Fe (3); Ti, Ru (4); Zr, Fe (5)) and [MeSi{SiMe2N(2-FC6H4)}(3)Ti-Fe(CO)(2)Cp] (9) establ ished the presence of unsupported metal-metal bonds [3, Ti-Fe 2.360(1); 4, Ti-Ru 2.5609(8); 5, Zr-Fe 2,605(2); 9, Ti-Fe 2.433(4) Angstrom]. Reaction o f the dinuclear complexes with isonitriles led to insertion of the substrat e into the polar metal-metal bond and the formation of the metallaiminoacyl complexes [MeSi{SiMe2N(R)}(3)M{eta(2)-(C=NR')M'(CO)(2)Cp}] (M = Ti, Zr, Hf ; M' = Fe, Ru; R p-tolyl, 2-C6H4; R' = Me, p-tolyl). The C-13 NMR resonance s of the isonitrile-derived carbon nuclei linking the two metal centers are observed at remarkably low field (delta 267.8-303.8). The structural propo sal for the insertion products was confirmed by an X-ray crystallographic s tudy of [MeSi{SiMe2N(p-tol)}(3)Ti{eta(2)-(C=NMe)Ru(CO)(2)Cp]. When the hete robimetallic complex [Me2SO, Me(Ph)SO, (PhCH2)(2)SO, (CH2)(4)SO], was react ed with sulfoxides [Me2SO, Me(Ph)SO, (PhCH2)(2)SO, (CH2)(4)SO], immediate o xygen transfer to a carbonyl ligand occurred, generating the dinuclear comp lexes [MeSi(SiMe2-NTol)(3)Zr(mu-O2C)RuCp(CO){S(R)R'}] (R R' = Me (23a); R = Me, R' Ph (23b); R, R' = (CH2)(4) (23c); R, R' = PhCH2 (23d)), in which th e two metal centers are linked by a CO2 ligand derived from a carbonyl liga nd in the starting material. In the presence of a second equivalent of sulf oxide, the Lewis acid-base adducts [MeSi(SiMe(2)NTol)(3)Zr{OS(R)R'-kappa O} (mu-O2C)RuCp(CO){S(R)R'}] (R = R' = Me (24a); R = Me, R' = Ph (24b); R, R' = (CH2)(4) (24c)) were formed. An X-ray crystal structure analysis of 24a e stablished the conversion of the carbonyl ligand to the bridging matallacar boxylate unit and the coordination of the thioether, formed in the oxygen t ransfer, to the Ru atom. The oxygen transfer from the sulfoxide to a carbon yl ligand was confirmed by an NMR study of the reaction using C-13-labeled carbonyl derivatives and O-17-labeled Me(Ph)SO.