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)Å. 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)Å.