Combining coordination chemistry with hydrogen bonds: perturbation of the structures by interaction of an organotin(IV) complex with O-donor solvent molecules

We have examined the role of different solvents in the crystallisation process of cis -octahedral, diphenyltin(IV)-bis-cupferronato complex, Ph2Sn(cupf)2 (1), where View the MathML sourcecupf=PhN2O2-. The Mössbauer spectra of frozen chloroform solution of 1 revealed the presence of cis and trans isomers. This cis–trans isomerisation was investigated by Mössbauer spectroscopy and the results inspired the synthesis of two new heptacoordinated derivatives: Ph2Sn(cupf)2(H2O) (2) and Ph2Sn(cupf)2(EtOH) · EtOH (3). In both compounds, the O-donor solvent molecules (H2O, EtOH) form novel Sn–O bonds with the Ph2Sn(IV) centre of 1, consequently the phenyl groups attached to tin undergo an intramolecular rearrangement. Compound 2 contains O–H ⋯ O hydrogen bonded infinite chains. In compound 3, O–H ⋯ O hydrogen-bonds and short O ⋯ O contacts assemble the complexes and uncoordinated solvent molecules into dimeric supramolecules. These solvents have structure-determining roles at both molecular and supramolecular levels: at molecular level the coordination of solvent determines intramolecular rearrangement by changing the conformation of the parent unsolvated complex, whilst at supramolecular level they control the association of solvated molecules via hydrogen bonds.