Unusual reactivity of methylphosphaalkyne (PCMe) toward digermenes and distannenes: stepwise formations of bridged 2,3,5,6-tetraphospha-1,4-dimethylidenecyclohexanes.
Reactions of methylphosphaalkyne, PCMe, with a digermene, R'' 2GeGeR'' 2 (R'' = -CH(SiMe 3) 2), and two distannenes, R'' 2SnSnR'' 2 and Ar' 2SnSnAr' 2 (Ar' = C 6H 2Pr (i) 3-2,4,6), have given moderate to high yields of the first bridged 2,3,5,6-tetraphospha-1,4-dimethylidenecyclohexanes, [R 2E{C(Me)(H)PC(CH 2)P}] 2 (R = R'' or Ar', E = Sn or Ge), all of which have been structurally characterized. Their mechanisms of formation are thought to involve successive [2 + 1] and [2 + 2] phosphaalkyne cycloaddition, heterocycle rearrangement, phosphaalkene/vinylphosphine tautomerization, and intermolecular hydrophosphination reactions. In one reaction, two intermediates have been spectroscopically observed and one trapped by coordination to one or two W(CO) 5 fragments, yielding the first diphosphagermole complexes, {[W(CO) 5} 1or2{R'' 2Ge[C(Me)PC(Me)P]}], which have been structurally characterized. Differences between the reactivities of PCMe and PCBu (t) are highlighted.
Jones
Cameron
C
School of Chemistry, Monash University, Clayton, Victoria 3800, Australia. cameron.jones@sci.monash.edu.au
Schulten
Christian
C
Stasch
Andreas
A