TIN(TV), MONOMETHYLTIN(IV), AND DIMETHYLT IN(IV) COMPLEXES WITH THIOLSULFUR AND HETEROCYCLIC NITROGEN DONORS - MOLECULAR-DYNAMICS AND STRUCTURE BY SN-119 MOSSBAUER-SPECTROSCOPY

The molecular dynamics of the complexes Sn(SPyN)(4) (1), SnCl2(SPyN)(2 ) (2), MeSn(SPy)(3) (3), MeSnCl(SPyN)(2) (4), Me(2)Sn(TCy)(2) (5), Me( 2)SnCl(TOx) (6), and Me(2)Sn(TUr) (7) [HSPy = 2-mercaptopyridine; HSPy N = 2-mercaptopyrimidine; HTCy = 2-thiocytosine; HTOx = 8-thioquinolin e; H(2)TUr = 2-thiouracil] has been investigated by variable temperatu re Sn-119 Mossbauer spectroscopy. The area under the resonant peaks ha s been determined as function of temperature, from which Debye tempera tures and cut-off frequencies, as well as recoil-free fractions (Lamb Mossbauer factor) and mean square displacements of Sn-119, have been c alculated. By fingerprint procedures on the basis of literature data, monomeric structures are attributed to complexes (1)-(4) and (6), whil e (5) and (7) lie in the borderline monomersmonodimensional polymers. The results are discussed on the basis of known crystal and molecular structures. The nature of the environment of tin atoms has been simula ted by point charge model calculations of nuclear quadrupole splitting parameters; molecular structures are proposed for complexes (5)-(7), where no X-ray diffractometric data are available.