SYNTHESIS AND CHARACTERIZATION OF NEW HYDROTRI(3,5-DIMETHYL-1-PYRAZOLYL)BORATE VANADIUM HALFSANDWICH COMPLEXES

Paramagnetic vanadium(III) complexes of the type TpVCl2(L) were prepa red by replacing the dimethylformamide ligand in TpVCl2(dmf) (1) by v arious N-containing heterocycles. The new compounds TpVCl2(L) (L=4 su bstituted pyridine NC5H4-R(4) (R = H (3a), CH3 (3b), C2H5 (3c), Ph (3d )), pyridazine (4), pyrimidine (5), pyrazine (6), imidazole (7a), 1-me thylimidazole (7b), 1,2-dimethylimidazole (7c), and 4,4'-bipyridine (8 )) were characterized by IR and mass spectroscopy, and the molecular s tructure of 3b was determined by X-ray crystallography. A binuclear pr oduct, [TpCl2V](2)(L-L) (9),containing 4,4'-bipyridine (L-L) as bridg ing ligand, and the dimethyl sulfoxide complex, TpCl-2(O=SMe2) (10), were also investigated. Reactions of 1 with phenol and triethylamine i n the presence of air gave TpV(O)(OPh)(2) (11). Other diamagnetic van adium(V) complexes such as TpV((NBu)-Bu-t)(SR)(2) (R = Et (12a), Ph ( 12b) and TpV((NBu)-Bu-t)(S2C6H4) (12c)) were obtained from the tert-b utylimido compound TpV((NBu)-Bu-t)Cl-2 (2) and the appropriate thiol in the presence of the base triethylamine. The H-1, C-13 and V-51 NMR spectra of 2, 11 and 12a-c are reported. (C) 1998 Elsevier Science S.A .