RECENT DEVELOPMENTS IN ORGANOMETALLIC CHEMISTRY

New cyclopentadienyl-imido compounds of molybdenum (and tungsten) have been prepared. They have an extensive chemistry in which the imido group behaves as a 4-electron donor spectator ligand. The structure of bis-eta-cyclopentadienyl compound [Mo(eta-C5H4R)2(NBu(t))] shows the eta-cyclopentadienyl rings are partially displaced from the metal by the ppi-donor electron pair on the imido nitrogen. In consequence a eta-cyclopentadienyl ring can be readily displaced. The ansa-sandwich compounds [M(eta-C5H4-CMe2-eta-C5H4)X2], where M = Mo or W and X2 = Cl2, H2, Me2, HPh, HMe have been prepared. These ansa bridged compounds are much more resistant to reductive elimination reactions than their non-ansa analogues. New transition metal compounds of the fullerence C60 have been prepared.