Synthesis, spectroscopic and structural aspects of some tetraorganodistannoxanes with internally functionalized oxime: crystal and molecular structures of [{R2Sn(ONC(Me)py)}2O]2 (R=Bun and Et) and 2-NC5H4C(Me)NOH

Diorganotin(IV) complexes of the type [{R2Sn(ONC(Me)py)}2O]2(R=Bun(1), Prn(2), Et (3) and Me (4)) have been synthesized by the condensation reaction of R2SnO with 2-NC5H4(Me)CNOH (5) in 1:1 molar ratio in refluxing anhydrous benzene–toluene and characterized by elemental analyses and IR and NMR (1H, 13C and119Sn) spectroscopy. Two sets of 119Sn chemical shifts are observed in the 119Sn-NMR spectra of all of these compounds indicating the presence of two types of environment around the tin atoms in solution. The crystal structures of 1, 3 and 5 have been established by single crystal X-ray diffraction. The bonding in 1 differs from that in 3 but in both structures two different environments around the tin atoms are evident with the geometry around each tin atom being that of a distorted trigonal bipyramid with alkyl groups at the equatorial positions. The structure of 5 consists of chains of molecules arising from intermolecular hydrogen bonding involving the nitrogen atom of the ring.