Photochemical synthesis and stereodynamic behavior of alkoxy-bridged (silylene)(germylene)iron complexes

Article abstract of DOI:10.1021/om00043a033

Mixed (silylene)(germylene)iron complexes have been synthesized for the first time and are internally stabilized by a donor bridging alkoxy group: [Cp′(CO)Fe{GeMe₂O(R)-SiMe₂}] (Cp′ = C₅Me₅; R = Me, Bu^t). Two-dimensional and variable-temperature ¹H NMR spectroscopies establish germylene-methyl group exchange. Computer simulation of the spectra and calculation using the Eyring equation yield values for ΔG^≠₂₉₈ for the process of 62 kJ mol^-1 (R = Me) and 61 kJ mol^-1 (R = Bu^t). A mechanism involving cleavage of the Ge-O partial bond, followed by rotation of the resulting coordinated germylene moiety about the Fe = Ge double bond, is proposed for this exchange. The (silylene)(germylene)iron complexes are weighted toward the (methoxysilyl)(germylene) form, indicating that germylene ligands are more stable than their silicon analogues.