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-dimethylthiourea (dmtu) have been prepared and characterised by IR, Raman and Sn-119 Mossbauer spectroscopies. The previously reported isomer shift (IS) values of SnBr4(dmtu)2 and SnI4(dmtU)2 have been revised to 0.98 and 1.32 mm s-1, respectively. The IS increases with decreasing electronegativity of the halogen atoms, and on going from dmu to dmtu complexes. The variation Of the IS of SnX4L2 complexes with the electronegativity of the halogen X and the donor atom of the ligand L is studied. The IS can be used to get information about the atoms bonded to tin. The shifts of nu(C=E) (E=O, S) and nu(as)(N-C-N) with respect to the free ligands, in the IR spectra of the complexes, indicate that the dmu and dmtu ligands coordinate through the 0 and S atoms, respectively. The structure of the complexes is discussed in terms of the Mossbauer quadrupole splitting and the tin-halogen stretching vibrations in the IR and Raman spectra.