Preparation, characterization and crystal structure of the adducts WF 6·F-py and WOF 4·F-py (F-py = 2-fluoropyridine)

Abstract

The adducts of tungsten(VI) WF 6·F-py and WOF 4·F-py were prepared from the reaction of WF 6 or WOF 4 with 2-fluoropyridine (F-py) in dichloromethane. The two adducts were characterized by X-ray powder data, and vibrational spectroscopy. The adduct of WOF 4 is only slightly volatile at room temperature, whereas that of WF 6 has a dissociation pressure of 26.5 mmHg at 21 °C. Solutions of these adducts in CD 2Cl 2 were studied by 19F, 1H, and 13C NMR spectroscopy. The crystal structures of WF 6·F-py and WOF 4·F-py have been determined by X-ray diffraction methods. Both adducts are of a molecular type. In WOF 4·F-py, the tungsten atom is surrounded by a distorted octahedron of ligands with the nitrogen atom of the organic ligand being trans to the oxygen atom and the equatorial plane made up of four fluorine atoms located at the corners of a square. The tungsten atom is displaced out of this plane toward the oxygen atom. In WF 6·F-py, the tungsten atom is surrounded by a capped trigonal prism of ligands with the nitrogen atom of the organic ligand occupying the capping site. The space groups, and unit cell parameters are as follows: WF 6·F-py, monoclinic, P2 1/c, a = 7.009, b = 15.373, c = 8.023Å, β = 101.62°, V = 847 Å 3, Z = 4; WOF 4·F-py, monoclinic, P2 1/c, a = 8.742, b = 9.349, c = 10.737 Å, β = 106.85°, V = 840 Å 3, Z = 4.