Experimental and ab initio structural study of the ketotin compounds,X_3SnCR_2CH_2COMe:crystal structures of X_3SnCMe_2CH_2COMe (X = Cl and I)

摘要

The MeCOCH_2CMe_2 ligand in X_3SnCMe_2CH_2COMe (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,X_3SnCH_2CH_2CO_2R (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(Cl_nI_(3-n)SnCMe_2CH_2COMe) (n = 0-3).Various ab initio calculations on 2 and X_3SnCH_2CH_2COMe (3) have been carried out.Comparisons of the theoretical and experimental structures of 2 for X = Cl or I are reported.