TETRAMETHYLPHOSPHOLYLURANIUM COMPLEXES AND THEIR PENTAMETHYLCYCLOPENTADIENYL ANALOGS

The mono- and bis-(tetramethylphospholyl)uranium complexes [U(tmp)(Cl)(3)(L)(2)] (tmp = C(4)Me(4)P, L = tetrahydrofuran or L(2) = dimethoxyethane), [U(tmp)(X)(3)] (X = BH4, CH(2)Ph) and [U(tmp)(2)(X)(2)] (X = Cl, BH4, alkyl, or alkoxide) were compared with their pentamethylcyclopentadienyl (cp*) analogues. The crystal structures of [U(tmp)(Cl)(3)(dimethoxyethane)] and [U(cp*)(2)(BH4)(2)] have been determined. Although the structures of the phospholyl compounds are similar to those of their cyclopentadienyl counterparts, the distinct electronic effects of the tmp and cp* ligands (tmp being less electron-donating than cp*) are manifest in the coordinating and redox properties of the complexes.