NEW NIOBIUM COMPLEXES WITH ALKYNES .4. A COMPOUND CONTAINING BOTH AN OXO-CENTERED TETRAMERIC ANION AND A RELATED DINUCLEAR CATION

A compound with the formula [Nb2(μ-Ph4C4)(μ-Cl)Cl2(THF)4]2[Nb4(μ-Ph4C4)2(μ4-0)(μ-Cl)4Cl4]·3C6H6·4THF has been prepared and characterized. Crystal data are as follows: space group, P21/c; a = 23.162 (5) Å, b = 15.235 (4) Å, c = 26.274 (5) Å, β = 111.91 (2)°, V = 8602 (4) Å3, and Z = 2. The tetranuclear anion is the same one previously described in other compounds with simpler cations. The cations in this case can be regarded as modified halves of the anion. They contain the same type of μ-PhCC(Ph)C(Ph)CPh ligand and have internal dimensions similar to those of each half of the anion. Given the structural relationship of the cation and anion, several hypotheses concerning their chemical relationship are considered. © 1990, American Chemical Society. All rights reserved.