Metallacyclohexatrienes or ‘metallabenzenes.’ Synthesis of osmabenzene derivatives and X-ray crystal structure of Os(CSCHCHCHCH)(CO)(PPh3)2

The first metallabenzene,O[graphic omittedH)(CO)(PPh3)2] has been prepared from Os(Co)(CS)(PPh3)3 and ethyen; X- ray crystal structure determination reveals a planar six-membered ring with no significant alternation of C–C bond lengths thus supporting the idea of electron delocalization within the ring.