Tetramerization of alkynes on a tungsten( 0 ) centre to form a cyclopentadienylvinylcarbene complex; crystal structure of [W(CO)(PhCCPh){η 5 -C 3 Ph 3 (C 5 Ph 5 )}]

Heating [W(CO)3(MeCN)3] or [W(CO)(PhCCPh)3] with an excess of diphenylacetylene produces [W(CO)(PhCCPh){η5-C3Ph3(C5Ph5)}], which contains a novel Cyclopentadienylvinylcarbene group through coupling of four alkyne ligands on the tungsten(O) centre.