VIBRATIONAL AND SN-119 MOSSBAUER-SPECTRA OF TIN(IV) HALIDE-COMPLEXES WITH 1,3-DIMETHYLUREA AND 1,3-DIMETHYLTHIOUREA

Tin(IV) halide complexes with 1,3-dimethylurea (dmu) and 1,3-dimethylt hiourea (dmtu) have been prepared and characterised by IR, Raman and S n-119 Mossbauer spectroscopies. The previously reported isomer shift ( IS) values of SnBr4(dmtu)2 and SnI4(dmtU)2 have been revised to 0.98 a nd 1.32 mm s-1, respectively. The IS increases with decreasing electro negativity of the halogen atoms, and on going from dmu to dmtu complex es. The variation Of the IS of SnX4L2 complexes with the electronegati vity of the halogen X and the donor atom of the ligand L is studied. T he IS can be used to get information about the atoms bonded to tin. Th e shifts of nu(C=E) (E=O, S) and nu(as)(N-C-N) with respect to the fre e ligands, in the IR spectra of the complexes, indicate that the dmu a nd dmtu ligands coordinate through the 0 and S atoms, respectively. Th e structure of the complexes is discussed in terms of the Mossbauer qu adrupole splitting and the tin-halogen stretching vibrations in the IR and Raman spectra.