DINUCLEAR ZIRCONIUM COMPLEXES WITH ME(2)SI(C5H4)(2) AS BRIDGING LIGAND - MOLECULAR-STRUCTURE OF [(ZR(ETA(5)-C5H3-BU(2)(T))ME)(2)(MU-O)((MU-ME(2)SI(C5H4)(2))]

The reaction of Li-2[Me(2)Si(C5H4)(2)] with 2 equivalents of [ZrLCl(3)] (L = C(5)Me(5) or C(5)H(3)Bu(2)(t)) in toluene under reflux gave the known [{Zr(C(5)Me(5))Cl-2}(2){mu-Me(2)Si(C5H4)(2)}] 1 and the new chloro derivative [{Zr(C5H3-Bu(2)(t))Cl-2}(2){mu-Me(2)Si(C5H4)(2)}] 2 in good yields. Addition of 4 equivalents of LiMe (or MgMeCl) to a pentane solution of 1 or 2 afforded the tetramethyl derivatives [{Zr(C5(M)e(5))Me(2)}(2){mu-Me(2)Si(C5H4)(2)}] 3 and [{Zr(C(5)H(3)Bu(2)(t))Me(2)}(2){mu-Me(2)Si(C5H4)(2)}] 4. Compound 3 is extremely moisture sensitive leading to the mu-oxo dinuclear complex [{Zr(C(5)Me(5))Me}(2)(mu-O){mu-Me(2)Si(C5H4)(2)}] 5, as demonstrated by H-1 NMR spectroscopy. Compound 4 reacted with water, in pentane or toluene, to give the mu-oxo dimethyl complex [{Zr(C(5)H(3)Bu(2)(t))Me}(2)(mu-O){mu-Me(2)Si(C5H4)(2)}] 6. Further reaction of 6 with water in toluene gave an unidentified insoluble yellow powder through the intermediate formation of a mu-dioxo methyl complex 7, identified by H-1 NMR spectroscopy. The crystal structure of 6 has been determined by X-ray diffraction methods: monoclinic, space group P2(1)/n, a = 15.494(4), b = 13.338(3), c = 19.933(4) Angstrom, beta = 107.19(1)degrees and Z = 4. Complex 6 is a dimer produced by the interaction of two Zr(eta(5)-C(5)H(3)Bu(2)(t))Me units bridged by one oxygen atom and the Me(2)Si(C5H4)(2) group.