SYNTHESIS AND SPECTROSCOPIC STUDIES (MOSSBAUER, IR AND NMR) OF [R(2)SNCL(2)BIPYM] (R=BUTYL OR PHENYL) AND THE CRYSTAL AND MOLECULAR-STRUCTURE OF [PH(2)SNCL(2)BIPYM]

The complexes [R(2)SnCl(2)bipym] (R = phenyl or butyl, bipym = 2,2',6, 6'-bipyrimidine) were synthesized and studied in solution by H-1- and C-13-NMR spectroscopy and in the solid state by IR and Mossbauer spect roscopy. The latter was also performed in frozen ethanolic solution. T he structure of the phenyl complex was determined by single crystal di ffraction methods. The value obtained for the angle C-Sn-C in the phen yl compound is 169.3(2)degrees (X-ray) and 151 degrees (Mossbauer), bu t the assignment of an octahedral configuration by Mossbauer spectrosc opy is consistent with the structure determined by diffraction. The bu tyl complex is also octahedral and the two techniques show better agre ement. The value of the C-Sn-C angle is 171 degrees (Mossbauer in the solid state), 163 degrees (Mossbauer in frozen solution) and 175.1(6)d egrees (X-ray). The NMR coupling constant, (1)J(Sn-119-C-13), was also used to estimate the C-Sn-C angle. The C-13-NMR spectrum for the buty l complex is markedly concentration-dependent. At the highest concentr ation, this angle is 138 degrees (Lockhart) and 145 degrees (Holecek); for less concentrated samples the angle tends to decrease. This sugge sts that the coordination number of tin in solution is less than six.