The compound μ-(C6H5)(CH3)Sn]2Fe2(CO)7 was synthesized to differentiate bridge deformation from iron-tin bond cleavage in R group interchange processes of stereochemically nonrigid [μ-R2Sn]2Fe2(CO)7 complexes. It is found from proton NMR studies that both processes can occur, the former with ΔG‡ = 11.8 ± 0.6 kcal/mol (298 K) and the latter with ΔG‡ = 19.2 ± 0.9 kcal/mol (298 K). The bridge deformation in the related, more soluble molecule [(n-C4H9)2Sn]2Fe2(CO)7 occurs with simultaneous, stereospecific interchange of bridge and terminal carbonyl ligands, as monitored by 13C NMR spectra. The complex [(C6H5)(CH3)SnFe(CO)4]2 exists in two isomeric forms which interconvert in solution with ΔG‡ = 25.5 ± 0.7 kcal/mol (298 K). The iron-tin bond cleavages are proposed to yield R2Sn→Fe stannylene intermediates.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry