PHOSPHINE AND PHOSPHINE OXIDE ADDUCTS OF VANADIUM(IV) CHLORIDE - SYNTHESIS AND STRUCTURAL STUDIES

The reaction products of VCl4 with PEt(3), PMe(3), PMe(2)Ph, Et(3)PO and PhMe(2)PO have been structurally characterized. Compound 1, [HPEt(3)][VCl4(PEt(3))(2)], crystallizes in space group C2/c with a = 17.422(2), b = 12.671(1), C = 13.390(1) Angstrom, beta = 95.76(2)degrees, V = 2941(2) Angstrom(3) and Z = 4. The [VCl4(PEt(3))(2)](-) anion has a trans arrangement of the phosphines with mean V-CI and V-P distances of 2.360(3) and 2.551(4) Angstrom, respectively. Compound 2, mer-VCl3(OPEt(3))(3), crystallizes in an orthorhombic cell (P2(1)2(1)2(1)) with a = 13.310(4), b = 17.754(6), c = 12.383(3) Angstrom, V = 2926(2) Angstrom(3) and Z = 4; V-CI distance (av.) = 2.396(7) and V-O (av.) = 2.00(2) Angstrom. Compound 3, mer-VCl3(PMe(2)Ph)(2)(OPMe(2)Ph) which has been reported before in a different space group, crystallizes with an orthorhombic (Pmn2(1)) unit cell: a = 13.590(4), b = 11.673(4), c = 8.964(4) Angstrom, V = 1422(1) Angstrom(3) and Z = 2. A mirror plane bisects the molecule. The V-CI, V-P and V-O distances are similar to those in 1 and 2. Compound 4, V2Cl6(PMe(3))(4), is a dinuclear compound which crystallizes with an orthorhombic unit cell (Pna2(1)) with cell dimensions: a = 11.470(4), b = 18.433(4); c = 13.677(4) Angstrom, V = 2892(2) Angstrom(3) and Z = 4; distance V-Cl-t (av.) = 2.30(1), V-Cl-b(av.) = 2.44(1) and V-P (av.) = 2.524(6) Angstrom. The phosphines have the common 1,3,6,8 arrangement. The V V distance of 3.691(2) Angstrom,is non-bonding. The reaction chemistry of these compounds is compared with that of the Nb and Ta analogs, and EPR measurements made on compound 1 are discussed. EPR spectra recorded for solutions of 1 in CH,CI, were shown to be due to about 1% of the vanadium in the form of VOC2(PEt(3))(2).