Heterodi- and heterotrinuclear complexes containing highly polar metal-metal bonds

Reaction of the dichlorozirconium complex [CH2(CH2NSiMe3)(2)ZrCl2(thf)2] (1), containing a chelating amido ligand and having a trans disposition of the chloro ligands established by an X-ray diffraction study, with the carbonylmetalate derivatives K[MCp(CO)(2)] (Cp = C5H5) and Na[Co(CO)(3)(PPh3)] gave the heterotrinuclear complexes [CH2(CH2NSiMe3)(2)Zr(MCp(CO)(2)}(2)] (M = Fe (2), Ru (3)) and [CH2(CH2NSiMe3)(2)Zr{Co(CO)(3)(PPh3)}(2)] (4), respectively. Of these, 2 and 3 were structurally characterized by X-ray crystallography, establishing two unsupported metal-metal bonds in each of the compounds [2, d(Zr-Fe) = 2.665(2), 2.664(2) Angstrom; 3, d(Zr-Ru) 2.7372(7), 2.7452(7) Angstrom]. Reaction of 2 and 3 with 1 in a I:1 molar ratio led to a quantitative redistribution of complex fragments, yielding the dinuclear complexes [CH2(CH2NSiMe3)(2)(Cl)Zr-MCp(CO)(2)] (M = Fe (5), Ru (6). Both products as well as the Zr-Co complex [CH2(CH(2)NsiMe(3))(2)(Cl)Zr-Co(CO)(3)(PPh3)] (7) were also obtained in moderate yields by reacting 1 with 1 molar equiv of the carbonylmetalate, Reacting 5-7 with NaCp gave the corresponding CpZrcomplexes [CH2(CH2NSiMe3)(2)(Cp)Zr-MCp(CO)(2)](M = Fe (8), Ru (9)) and [CH2(CH2NSiMe3)(2)(Cp)Zr-Co(CO)(3)(PPh3)] (10), of which 9 was characterized by a single-crystal X-ray structure analysis [d(Zr-Ru) 2.8297(14) Angstrom]. Compounds 5, 6, 8, and 9 insert methyl isonitrile to give the heterobimetallic metallaiminoacylzirconium complexes [CH2(CH2NSiMe3)(2)(Cl)Zr{eta(2)-C(=NCH3)MCp(Co (M = Fe (11), Ru (12)) and [CH2(CH2NSiMe3)(2)(Cp)Zr{eta(2)-C(=NCH3)MCp(CO)(2)}] (M = Fe (13), Ru (14)), respectively. Reaction of the heterotrinuclear compounds 2 and 3 with isonitriles exclusively gave the products of the insertion into one of the unsupported metal - metal bonds, [CH2(CH2NSiMe3)(2)Zr{eta(2)-C(=NCH3)MCp(CO)(2)}{MCp(CO)(2)}] (M = Fe, R = Me, Bu-n, Cy, Tol(15a-d); M = Ru, R = Me, Bu-n, Cy, Tol(16a-d)). A crystal structure analysis of 16a established the insertion into one of the metal-metal bonds while the intact Zr-Ru bond was elongated in comparison to that of 3 [d(Zr-Ru) = 2.8639(6) Angstrom]. Cleavage of both metal-metal bonds in 2 and 3 was observed in reactions with sulfoxides. Transfer of the S-bound oxygen atom to a carbonyl ligand led to CO2-linked trinuclear complexes in which the thioether thus generated was coordinated to the late transition metal center. The reaction at the two metal-metal bonds occurred cooperatively, precluding the isolation of intermediates.