Synthesis and Characterization of Triplet Germylene-bridged Diiron Complexes and Singlet Stannylene-bridged Diiron Complexes

Photoreaction of CpFe(CO)2Me with sterically congested R2GeH2 [R = 2,4,6-C6H2^iPr3 (Tip), 2,4,6-C6H2Me3 (Mes)] afforded paramagnetic germylene-bridged diiron complexes having a triplet ground state, Cp2Fe2((mu)-CO)2((mu)-GeR2) (3a, R = Tip; 3b, R = Mes), while the analogous reaction with R2SnH2 afforded diamagnetic complexes Cp2Fe2(CO)2((mu)-CO)((mu)-SnR2) (trans-5a, R = Tip; trans-5b, R = Mes). The structure of 3a was determined by X-ray crystallography.