Synthesis and reactivity of bis(η-cyclopentadienyl) trimethyltin derivatives of niobium: crystal and molecular structure of [{Nb(η-C5H5)2(SnMe3)}2(µ-O)

Abstract

The reaction between [Nb(η-C5H5)2H3] and LiBu followed by SnMe3Cl gives [Nb(η-C5H5)2H2(SnMe3)]2, also produced from [Nb(η-C5H5)2H3] and SnMe3H. Heating 2 with styrene, PMe3, isoprene or but-2-yne gives [Nb(η-C5H5)2L(SnMe3)](L =η-H2CCH–C6H5, 3; PMe3, 4; η-H2CCHCMeCH2, 5; or η-C2Me26). Photolysis of complex 3 in the presence of CO, 2,6-Me2C6H3NC, MeCN, or PMe3 gives [Nb(η-C5H5)2L(SnMe3)](L = CO, 7; 2,6-Me2C6H3NC, 8; η2-MeCN, 9a and 9b; or PMe3, 4). Heating 3 with H2 regenerates 2 and releases styrene. Compound 3, 5 or 6 reacts with SnMe3H to give the bis(stannyl) derivative [Nb(η-C5H5)2H(SnMe3)2]10, which is also formed by prolonged heating of [Nb(η-C5H5)2H2(SnMe3)] with SnMe3H. Photolysis of 3 under CO2 gives a mixture of 7 and [{Nb(η-C5H5)2(SnMe3)}2(µ-O)]11 by cleavage of the CO2 molecule. Compound 11 crystallises in the orthorhombic space group Pbca with a= 8.409(3), b= 21.109(4) and c= 15.582(3)A. The bridging oxygen atom sits on a crystallographic inversion centre giving a linear Nb–O–Nb group with Nb–O 1.9434(4) and Nb–Sn 2.8619(5)A.