2,2′-Bipyridyl adducts of tungsten oxide fluorides: preparation and characterization of WOF4bipy and WO2F2bipy; crystal structure of WO2F2bipy

WOF 4* bipy was prepared from the reaction of WOF 4 with 2,2′-bipyridyl (bipy) in the melt or in solution in CH 2 Cl 2 or CH 3 CN.The adduct, which is not moisture-sensitive at room temperature, was characterized by elemental analysis, X-ray powder data, and vibrational spectroscopy. WOF 4* bipy is almost insoluble in the usual organic solvents, and the species which were observed in CH 2 Cl 2 or CH 3 CN by 1 H NMR and Raman spectroscopy resulted from the dismutation of WOF 4* bipy into WO 2 F 2* bipy and WF 6* bipy.This transformation in solution was revealed by the slow growing of crystals identified as WO 2 F 2* bipy and by the 1 H NMR spectrum which displayed lines assigned to the independently synthesized and characterized species WF 6* bipy. Unlike the WOF 4 adduct, the tungstyl adduct is moisture-sensitive, its crystal structure showed that the tungsten atom is surrounded by a very distorted octahedron of ligands with each nitrogen of the bipy ligand trans to one oxygen atom and the two fluorine atoms trans to each other. The space group, unit cell parameters, and R factor for C 10 H 8 F 2 N 2 O 2 W are as follows: monoclinic, P2 1 / n (No. 14) (alternate setting of the standard space group P2 1 / c ), a = 8.637(1) Å, b = 13.823(2) Å, c = 9.526(2) Å, β = 109.98(2)°, V = 1068.8(6) Å 3 , Z = 4, and R = 0.044 for 806 (I > 3σ(I)) of 1471 total reflections and 94 parameters. Keywords: 2,2′-bipyridyl adducts, tungsten oxide tetrafluoride, tungsten dioxide difluoride.