Characterisation of organotin(IV) derivatives of 1,6-bis(pyrimidin-2ylthio)hexane by Mossbauer spectroscopy
A series of tin(IV) derivatives of 1,6-bis(pyrimidin-2-ylthio)hexane (pth) have been investigated by Mössbauer spectroscopy to elucidate aspects concerning structure and bonding in solid state. The SnClPh3 (1) and SnCl2Ph2 (2) derivatives have 5- and 6-coordinate metal centres respectively. The phenyl groups of the diphenyltin(IV) derivative are in cis configuration as revealed by its isomer shift and quadrupole splitting as well as by the estimated C-Sn-C bond angle. The spectrum of the SnCl3Ph (3) derivative reveals three phases in solid state as a mixture of chemicals having tetrahedral and octahedral geometries. The magnitude of both isomer shift and quadrupole splitting of SnCl3Ph (3a) is smaller than the other two sites (3b and 3c) as a result of dephenylation of the metal precursor. The SnCl4 (4) derivative has an octahedral geometry with the ligand bonded through the pyrimidyl moiety of pth. This polydentate compound is a weak s-donor, in comparison to pyrazin, and it is acting as a bridging-bidentate as well as bridging-tetradentate ligand upon coordination. The r value (QS/IS ratio) of all organotin(IV) derivatives supports coordination number higher than four, except the compound from the 3c site.