Compounds of Germanium and Tin, 20. Stannylene Complexes of Iron and Nickel without Donor Stabilization†‡

Treatment of [Fe2(CO)9], [Fe3(CO)12] or [Ni(CO)4] with the alkylarylstannylene RR′Sn: [R= 2,4,6-tBu3C6H2, R′ = CH2C(CH3)2-3,5-tBu2C6H3] furnishes the stannylene complexes [(OC)4Fe=SnRR′] (5) and [(OC)3Ni=SnRR′]. The X-ray structure analysis of 5 reveals a trigonal-bipyramidal environment of the iron atom with the tricoordinated tin atom occupying an axial site, thus indicating that RR′Sn: is a strong σ-donor but weak π-acceptor.