Tungstaarsirenes: Synthesis and structure of eta(2)-arsinocarbene complexes of tungsten [(eta(5)-C5H5)(CO)(2)W=C(R)-AsPh2][PF6]

The reaction of the carbyne complexes (eta(5)-C5H5)(CO)(2)W=CR (R = Me, Ph, Tol) with chlorodiphenylarsine, Ph2AsCl, provides in the presence of thallium hexafluorophosphate the novel cationic eta(2)-arsinocarbene complexes [(eta(5)-C5H5)(CO)(2)W=C(R)-AsPh2][PF6] (2a-c) in high yields. The constitution of the new tungstaarsacyclopropene complexes was determined by spectroscopic investigation and, in the case of the 4-methylphenyl-substituted compound 2c, additionally by X-ray single-crystal structure determination.