Some further studies of estertin compounds. Crystal structures of [NEt4][MeO2CCH2CH2Sn(dmio)(2)] (dmio = 1,3-dithiole-2-one-4,5-dithiolato) and (MeO2CCH2CH2)(2)SnX2[X-2 = I-2, (NCS)(2) or Cl, Br]

Estertin compounds, (MeO2CCH2CH2)(2)SnX2 [X-2 = I-2 (2); X-2 = Br-2 (9); X-2 = Cl,Br (4); or X-2 = (NCS), (3)] have been obtained by halide exchange reactions of (MeO2CCH2CH2)(2)SnCl2. Crystal structure determinations of 2-4 revealed chelating MeO2CCH2CH2 units with distorted octahedral geometries at tin. The Sn-O bond lengths in the isothiocyanato complex, 3, are shorter [2.390(11) to 2.498(12), mean 2.439 Angstrom], with the chelate bite angles, C-Sn-O, larger [74.3(7) to 78.2(6), mean 76.0 degrees] than those in the halide analogues 2 and 4 [Sn-O = 2.519(2) to 2.541(8), mean 2.530 Angstrom; C-Sn-O 72.8(3) to 73.9(4), mean 73.3 degrees]. H-1, C-13 and Sn-119 NMR and IR spectra of 2-4 and 9 were determined in CDCl3 solution : the NMR spectra of (MeO2CCH2CH2)(2)SnX2 show the following trends: (i) both delta(1)H(alpha) and delta(13)C(alpha), increase and (ii) both (2)J(Sn-H) and (1)J(Sn-C) decrease in the sequence X-2 = (NCS)(2), Cl-2, ClBr, Br-2 and I-2. The MeO2CCH2CH2 and dmio groups (dmio = 1,3-dithiole-2-one-4,5-dithiolato) are all chelating groups in (MeO2CCH2CH2)(2)Sn(dmio) (5). As shown by X-ray crystallography, the tin atom in the anion of solid [Q][MeO2CCH2CH2Sn(dmio)(2)] 6 (Q = NEt4) forms 5 strong bonds [to C and the 4 thiolato S atoms, Sn-S 2.459(2) to 2.559(2) Angstrom], arranged in a near trigonal bipyramidal array. There is an additional intramolecular, but weaker, interaction with the carbonyl oxygen atom [Sn-O = 3.111(5) Angstrom]; v(C=O) = 1714 cm(-1) in solid 6 (Q = NEt4). NMR spectra of 5 and 6 are also reported. (C) 1997 Elsevier Science Ltd.