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 I), 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, ∑(Cl_nI_3?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 © 2005 John Wiley & Sons, Ltd.