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 o f novel organotin halides and carboxylates containing bulky organic li gands (adamantyl, triptycyl). The Mossbauer spectra are discussed in t erms 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 Moss bauer quadrupole splittings and with the electronegativities of the li gands 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 f rom 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 significa ntly longer than the three Sn-C(phenyl) bonds. The structure is compar ed to those of other similar compounds.