Alkyl chloro, dialkyl and mixed alkyl derivatives of imido(pentamethylcyclopentadienyl) tantalum(V). X-ray crystal structure of [TaCp*Cp′Cl{N(2,6-Me 2C 6H 3)}], (Cp′= η5-C 5H 4SiMe 3

Abstract

[TaCp*Cl 2{N(2,6-Me 2C 6H 3)}] (Cp*= η 5-C 5Me 5) reacts with one equivalent of LiR (R=CH 2SiMe 3, CH 2CMe 2Ph, CH 2CMe 3, 2-(CH 2NMe 2)C 6H 4, C 5H 4SiMe 3) or 0.5 equivalents of Mg(CH 2C 6H 5) 2(THF) 2 to give the alkyl chloro complexes [TaCp*ClR{N(2,6-Me 2C 6H 3)}],(R=CH 2SiMe 3, 1; CH 2CMe 2Ph, 2; CH 2CMe 3, 3; CH 2C 6H 5, 4; 2-(CH 2NMe 2)C 6H 4, 5; C 5H 4SiMe 3, 6). When the same reaction was carried out with two equivalents of lithium or one equivalent of magnesium reagent, the corresponding dialkyl derivatives [TaCp*R 2{N(2,6-Me 2C 6H 3)}],(R=CH 2SiMe 3, 7; CH 2CMe 2Ph, 8; C 6H 5, 9; CH 2C 6H 5, 10; CH 2CMe 3, 11) were obtained. The mixed alkyl derivatives [TaCp*MeR{N(2,6-Me 2C 6H 3)}], (R=CH 2SiMe 3, 12; CH 2CMe 2Ph, 13; C 6H 5, 14; CH 2CMe 3, 15; 2-(CH 2NMe 2)C 6H 4, 16; CH 2C 6H 5, 17; C 5H 4SiMe 3, 18) have been prepared by treatment of solutions containing [TaCp*ClMe{N(2,6-Me 2C 6H 3)}] with one equivalent of lithium or 0.5 equivalents of magnesium reagent. All the new complexes were characterized by the usual IR and NMR spectroscopic methods. The crystal structure of 6 was determined by X-ray diffraction studies. Crystals of 6 are monoclinic, space group P2 1/ c, with Z=4 in a unit cell of dimensions a=12.597(3), b=11.338(2), c=18.297(4) Å and β=96.53(3)°. The structure was solved from diffractometer data by a combination of direct and Fourier methods and refined by full-matrix least squares fit on the basis of 4846 observed reflections to R 1 and wR 2 values of 0.0224 and 0.0574, respectively.