Self-assembly of diorganotin(IV) moieties and 2-pyrazinecarboxylic acid: syntheses, characterizations and crystal structures of monomeric, polymeric or trinuclear macrocyclic compounds

A series of diorganotin(IV) compounds of the type [R2Sn(pca)Cl](3) (R = CH3 1; Bu-n 2; C6H5 3; C6H5CH2 4; Hpca = 2-pyrazinecarboxylic acid), R2Sn(pca)(2)(mH(2)O).nH(2)O (m = 1: R = CH3, n = 2 5, R = Bu-n, n = 0 6; m = 0, n = 0: R = Bu-n 7, C6H5 8, C6H5CH2 9) and (Et3NH)(+)[R2Sn(pca)(2)Cl](-).mH(2)O (m = 0: R = CH3 10, Bu-n 11, C6H5CH2 13; m = 1: R = C6H5 12) have been obtained by reactions of 2-pyrazinecarboxylic acid with diorganotin( IV) dichloride in the presence of sodium ethoxide or triethylamine. All compounds were characterized by elemental, IR and NMR spectra analyses. Except for compounds 3, 4, 7, 11 and 13, the others were also characterized by X-ray crystallography diffraction analyses, which revealed that compounds 1 and 2 were trinuclear macrocyclic structures with six-coordinate tin( IV) atoms, compounds 5 and 6 were monomeric structures with seven-coordinate tin(IV) atoms, compounds 8 and 9 were polymeric chain structures with seven-coordinate tin (IV) atoms and compounds 10 and 12 were stannate with seven-coordinate tin( IV) atoms.