Experimental and ab-initio structural study of the ketotin compounds, X₃SnCR₂CH₂COMe. Crystal structures of X₃SnCMe₂CH₂COMe (X = Cl and I)

The MeCOCH2CMe2 ligand in X3SnCMe2CH2COMe (2; X = halide) acts as a C,O-chelating group both in the solid state and in non-coordinating solutions. The intramolecular Sn-O bond lengths in trigonal bipyramidal 2 (X = Cl and 1), as determined by X-ray crystallography, indicate that the stronger interaction occurs in 2 X - Cl. Comparisons with the Sn-O bond lengths in the estertin trihalides, X3SnCH2CH2CO2R (1; R - Me), suggest that the latter form stronger chelates than do 2. In chlorocarbon solution, 2 (X = Cl, I) undergoes exchange reactions, as shown by NMR spectra, to give all possible halide derivatives, Sigma(ClnI3-nSnCMe2CH2COMe) (n = 0-3). Various ab initio calculations on 2 and X3SnCH2CH2COMe (3) have been carried out. Comparisons of the theoretical and experimental structures of 2 for X = Cl or I are reported. Copyright (c) 2005 John Wiley & Sons, Ltd.