Synthesis, characterisation, Mössbauer spectra, and structures of some trinuclear iron–tin clusters

Abstract

Reactions of [Fe₃(CO)₁₂] with diaryltin species SnR₂(R¹= 2,4,6-triisopropylphenyl, R²= 2,6-diethylphenyl, R³= pentamethylphenyl) and with Sn[CH(PPh₂)₂]₂ have been investigated. The tin reagents SnR₂(R = R¹ or R²) reacted under mild conditions to give in moderate yields the trinuclear species [Fe₂(CO)₈(µ-SnR¹₂)]1 or [Fe₂(CO)₈(µ-SnR²₂)]2, as orange-red crystalline solids, which decompose in air on prolonged exposure. The compound [Fe₂(CO)₈(µ-SnR⁴₂)]3(R⁴= 2,4,6-triphenylphenyl) can be similarly obtained. Prolonged treatment of the carbonyl with the novel tin reagent SnR³₂, by contrast, afforded the known compound spiro-[(OC)₈Fe₂SnFe₂(CO)₈]4 for which data are briefly reported. Reactions with tin or lead reagents M[CH(PPh₂)₂]₂(M = Sn or Pb) afforded [Fe₂(CO)₆(µ-CO)(µ-dppm)][dppm = 1,2-bis(diphenylphosphino)methane] rapidly and almost quantitatively. Full crystal and molecular structural data are reported for [Fe₂(CO)₈(µ-SnR¹₂)] and [Fe₂(CO)₈(µ-SnR²₂)]. Mössbauer data are also presented for compounds 1–3, and interpreted in terms of the structural data for these and other systems.