SN-119 MOSSBAUER AND NUCLEAR-MAGNETIC-RESONANCE STUDIES OF ORGANOTIN COMPOUNDS .2. STERICALLY CROWDED ORGANOTIN HALIDES AND CARBOXYLATES

Tin-119 Mossbauer and Sn-119 NMR data have been obtained fora number of novel organotin halides and carboxylates containing bulky organic ligands (adamantyl, triptycyl). The Mossbauer spectra are discussed in terms of distortions from tetrahedral geometries as a result of steric crowding. The largest distortions occur for the adamantyl derivatives. A detailed study of Sn-119 NMR shifts revealed correlations with Mossbauer quadrupole splittings and with the electronegativities of the ligands concerned. The crystal structure of (E)-(but-2-enyl)triphenyltin was determined: triclinic, space group P1BAR, with a = 9.892(3), b = 10.196(4), c = 11.637(5) angstrom, alpha = 107.16(2), beta = 103.40(2), gamma = 109.77(2)degrees. The crystals are composed of discrete non-interacting molecules. The structure was refined to R 0.035 and R' = 0.043. The geometry around the tin centres is only slightly distorted from tetrahedral with bond angles ranging between 107.5(2) and 112.8(2)degrees, average 109.5-degrees. The Sn-C(but-2-enyl) bond is significantly longer than the three Sn-C(phenyl) bonds. The structure is compared to those of other similar compounds.