NEW CLASS OF TRINUCLEAR TUNGSTEN(IV) CLUSTER COMPOUNDS WITH W-W SINGLE BONDS

The reaction of tungsten hexacarbonyl with carboxylic acids, followed by suitable workup procedures, allows the isolation of compounds whose common feature is the presence of a [W3O2(O2CR)6]2+ unit, to which three additional donors are coordinated. This consists of an equilateral triangle of tungsten atoms with oxygen atoms on the threefold axis above and below the triangle so that the W3O2 set of atoms defines a trigonal bipyramid. Each W-W edge is bridged by two bidentate carboxylato ions. Each tungsten atom is coordinated by an additional ligand, such as H2O or an anion, and is therefore nine-coordinate, counting its neighboring tungsten atoms. The W-W distances, which are all about 2.75 Å, are consistent with the existence of W-W single bonds. Additional anions or cations are present as necessary for electroneutrality. Four compounds, all of which have been structurally characterized by X-ray crystallography, are reported here: 1, {[W3-O2(02CCH3)6](H2O)3}(CF3SO3)2; 2, {[W3O2(O2CC2H5)6](H2O)3}(BF4)2•5.5H20; 3, {[W3O2(O2CC(CH3)3)6](O2CC(C-H3)3)2(H20)}(CH3)3CCO2H; 4, Cs{[W302(O2CCH3)6](CH3C02)3|-3H20. All four are yellow solids and are stable in air. The principal crystallographic data for each of the compounds are as follows: (1) monoclinic C2/c, a = 19.798 (5) Å, b = 11.424 (5) Å, c= 15.079 (5) Å, β = 115.94(5)°, V= 3067 Å3, Z = 4; (2) triclinic P1, a = 13.285 (6) Å, b = 12.614 (5) Å, c = 12.453 (5) Å, α = 93.84 (5)°, β = 92.17 (5)°, γ = 102.37 (5)°, V = 2031 Å3, Z = 2; (3) orthorhombic Pnnm, a = 16.159 (3) Å,b = 26.053 (6) Å, c = 16.941 (3) Å, V = 7132 Å3, Z = 4; (4) monoclinic C2/c, a = 20.702 (5) Å, b = 12.987 (2) Å, c = 25.535 (5) Å, 0 92.61 (6)°, V= 6858 Å3, Z = 8. © 1978, American Chemical Society. All rights reserved.