119Sn Chemical Shifts in five- and six-coordinate organotin chelates

Abstract

119Sn chemical shifts, δ( 119Sn), relative to Me 4Sn in five- and six-coordinate organotin chelates were measured by means of FT NMR spectroscopy. 119Sn resonances were found to lie between ca. −90 and −330 ppm in the five-coordinate compounds and between ca. −125 and −515 ppm in the six-coordinate derivatives. thus δ( 119Sn) moves upfield by 60–150 ppm with a change of the coordination number of tin from four to five and by 130–200 ppm from five to six. the δ( 119Sn) values were shifted depending on the nature of chelating ligands and this shift was discussed in terms of the bonding between the ligand and tin. Replacement of methyl groups attached to tin by phenyl groups in five- and six-coordinate compounds induces upfield shifts in δ( 119Sn) parallel to those found in four-coordinate organotin halides.