89637-13-8Relevant academic research and scientific papers
Preparative, structural, and spectroscopic studies of tetrakis(carboxylato)ditungsten(II) compounds with W-W quadruple bonds
Cotton, F. Albert,Wang, Wenning
, p. 1604 - 1610 (2008/10/08)
Preparative procedures affording the following compounds in good yield are described: orange W2(O2CC6H5)4(C 4H8O)2 (1), orange W2(O2CC6H4-p-OCH3) 4(C4H8O)2·2C 4H8O (2), and red W2[O2CC6H2[2,4,6-(CH 3)3]]4-2CH3C6H 5 (3). The general route is by reduction of WCl4 in THF using Na/Hg in the presence of the appropriate sodium carboxylate. Each compound has been obtained in crystalline form and characterized by X-ray crystallography. The compounds are all quite sensitive to oxygen and moisture, especially in solution. Crystal data are as follows: (1) P21/c with a = 9.511 (7) A?, b = 17.716 (7) A?, c = 10.843 (3) A?, β = 109.52 (4)°, and Z = 2; (2) P1 with a = 11.590 (4) A?, b = 14.421 (3) A?, c = 8.278 (2) A?, α = 100.77 (2)°, β = 103.23 (2)°, γ = 68.55 (2)°, and Z = 1; (3) P21/c with a = 8.141 (3) A?, b = 21.873 (4) A?, c = 14.244 (3) A?, β = 102.41 (2)°, and Z = 2. In each case the molecule resides on an inversion center. The W-W distances in 1-3 are 2.196 (1), 2.203 (1), and 2.176 (1) A?, respectively. The shorter distance in 3 may be due to the absence of axial ligands. In 1 and 2 each phenyl group is nearly coplanar with its carboxyl group whereas in 3 it is nearly perpendicular. The visible spectra of 1, 2, 3, and W2(O2CC6H4(4-CN))4 have been studied and compared to the spectra of the molybdenum analogues. In 1 and 2 there are clearly two overlapping absorption bands in the 500-600-nm region and it is proposed that the one at lower energy is due to the δ → δ* transition while the other one is due to a δ → π*L transition. Other aspects of the spectra are discussed.
