AMPHIPHILIC QUALITIES OF ETA(2)-PHOSPHINO CARBENE COMPLEXES OF TUNGSTEN

eta(2)-Phosphinocarbene complexes of tungsten containing a trimethyl-p hosphine ligand show an amphiphilic behavior. With the Lewis acid SMe( +) an electrophilic attack occurs at the metal-carbon double bond to g ive 1-tungsta-2-phospha-4-thia-bicyclo[1.1.0]butane complexes. On the contrary the Lewis base, PMe(3), adds at the carbene carbon atom to yi eld a cationic trimethylphosphoraneylidene complex. However, treatment of hosphino)methylcarbene]-tungsten-tetraphenylborate with the less n ucleophilic triethylamine causes deprotonation at the methyl group pro viding entadienyl)-eta(2)-diphenylphosphinovinyltungsten.