The Reaction of Potassium Polyselenides with [CpW(CO)3Cl] in DMF - Formation and Crystal Structure of [CpW(CO)3SeC(O)NMe2] and {[CpW(CO)3]2Se4}

Abstract

The reactions of the potassium polyselenides „K2Se6” and „K2Se8” with [CpW(CO)3Cl] and 18-crown-6 in DMF lead to a mixture of the selenido complexes {[CpW(CO)3]2Se4} 1 and [(18-crown-6)K]+[CpW(Se4)2]−3 and the Se−bonded selenocarbamato complex [CpW(CO)3SeC(O)NMe2] 2 in yields depending on the selenium content of the used potassium polyselenides („K2Se6” or „K2Se8”). A similar reaction in THF produces {[CpW(CO)3]2Se4} as the main product. X-ray structures of 1 and 2 were determined. In 1 the Se4-chain is bonded in a μ2-η1 fashion, with corresponding W−Se bond lengths of 264.0(1) and 264.3(1) pm. The Se−Se bond lengths lie in the range 232 to 237 pm. The first example of an η1 Se-bonded selenocarbamato ligand is observed in the crystal structure of 2, with a W−Se bond length of 263.1(1) pm. The 77Se-NMR data are compared with the corresponding data of related complexes.