Synthesis and characterisation of tin(IV) and organotin(IV) derivatives 2-{[(2-hydroxyphenyl)imino]methyl}phenol

From the interaction of 2-{[(2-hydroxyphenyl)imino]methyl}phenol(salopH2) with tin and organotin(IV) acceptors, the derivatives [SnR3(salopH)] (R=Me or Bun), [SnR2(salop)] (R=Me, Bun, But, Vin or Ph), [SnRX(salop)(solvent)] (R=Me, Bun, Ph or X; X=Cl, Br or I; solvent=CH3OH or H2O), [Sn(salop)2], [R2SnCl2(salopH2)] (R=Me or Bun) have been obtained and characterised. The chelates, containing the Schiff base in mono or dianionic form, are generally stable both in the solid state and in solution, whereas the [SnR2Cl2(salopH2)] adducts slowly decompose in acetone or DMSO yielding [SnR2(salop)] and releasing HCl. All the [SnR2(salop)] and [SnRX(salop)(solvent)] complexes are fluxional in solution. The 119Sn NMR chemical shift is a function of the number of R groups. The X-ray single crystal diffraction study of [SnVin2(salop)] shows the metal to be five-coordinate in a distorted square pyramidal environment, SnC distances being 2.112(2) and 2.113(2) Å, SnO 2.117(2) and 2.125(2) Å and SnN 2.227(2) Å. The whole structure consists of molecular units connected by weak intermolecular SnO interactions. In the complexes [SnX2(salop)(CH3OH)]·CH3OH complexes (X=Cl or Br), the tin atom is found in a strongly distorted octahedral environment with the SnO bond ranging from 1.995(3) to 2.055(2) Å. The SnN bond is 2.116(4) Å in the bromide and 2.171(3) Å in the chloride complex.