Flexible coordination of the carboxylate ligand in tin(ii) amides and a 1,3-diaza-2,4-distannacyclobutanediyl

Abstract

A series of tin(II) amido complexes possessing m-terphenyl carboxylate ligands have been prepared. These complexes, namely [(Me₃Si)₂NSn(µ-O₂CC₆H₂Ph₃)]₂, [(Me₃Si)₂NSn(µ-O₂CC₆H₃Mes₂)]₂, and [(Me₃Si)₂NSn(µ-O₂CC₆H₂Mes₂Me)]₂ [Mes = 2,4,6-trimethylphenyl], are the first structurally characterized examples of tin(II) carboxylate complexes exhibiting discrete Sn₂O₄C₂ heterocyclic cores. Initial reactivity studies led to the isolation of a 1,3-diaza-2,4-distannacyclobutanediyl, [(Mes₂C₆H₃CO₂)Sn(µ-NSiMe₃)]₂. This molecule possesses a Sn₂N₂ heterocyclic core and it was crystallised as both the CH₂Cl₂ and Et₂O solvates. Although the tin atoms in this molecule have a formal oxidation state of 3+, preliminary computational studies on this molecule suggest that it is best described as a ground state singlet. Finally, the X-ray crystal structure of (CH₂Cl)(Cl)Sn[N(SiMe₃)₂]₂, the product of oxidative addition of CH₂Cl₂ to Sn[N(SiMe₃)₂]₂, is also presented herein.