Reactivity of Boryl- and Silyl-Substituted Carbenoids toward Alkynes: Insertion and Cycloaddition Chemistry

Three modes of reactivity of phenyl-substituted alkynes toward acyclic tetrelenes are reported, with reaction pathways found to be dependent not only on the nature of the group 14 element but also on the supporting ligand set. Systems featuring Sn–B or Ge–B bonds undergo insertion chemistry, forming borane-appended (vinyl)­Sn^II and Ge^II species. With a bis­(amido)­stannylene, phenylacetylene acts as a protic acid, generating a Sn^II acetylide with a unique bridged structure. Reactivity toward a more strongly reducing Si^II system is dominated by the possibility of accessing Si^IV via [2 + 1] cycloaddition chemistry

Oxidative Bond Formation and Reductive Bond Cleavage at Main Group Metal Centers: Reactivity of Five-Valence-Electron MX₂ Radicals

Monomeric five-valence-electron bis­(boryl) complexes of gallium, indium, and thallium undergo oxidative M–C bond formation with 2,3-dimethylbutadiene, in a manner consistent with both the redox properties expected for M^II species and with metal-centered radical character. The weaker nature of the M–C bond for the heavier two elements leads to the observation of reversibility in M–C bond formation (for indium) and to the isolation of products resulting from subsequent B–C reductive elimination (for both indium and thallium)

Oxidative Bond Formation and Reductive Bond Cleavage at Main Group Metal Centers: Reactivity of Five-Valence-Electron MX₂ Radicals

Monomeric five-valence-electron bis­(boryl) complexes of gallium, indium, and thallium undergo oxidative M–C bond formation with 2,3-dimethylbutadiene, in a manner consistent with both the redox properties expected for M^II species and with metal-centered radical character. The weaker nature of the M–C bond for the heavier two elements leads to the observation of reversibility in M–C bond formation (for indium) and to the isolation of products resulting from subsequent B–C reductive elimination (for both indium and thallium)

Oxidative Bond Formation and Reductive Bond Cleavage at Main Group Metal Centers: Reactivity of Five-Valence-Electron MX₂ Radicals

Monomeric five-valence-electron bis­(boryl) complexes of gallium, indium, and thallium undergo oxidative M–C bond formation with 2,3-dimethylbutadiene, in a manner consistent with both the redox properties expected for M^II species and with metal-centered radical character. The weaker nature of the M–C bond for the heavier two elements leads to the observation of reversibility in M–C bond formation (for indium) and to the isolation of products resulting from subsequent B–C reductive elimination (for both indium and thallium)