Heptacoordination in Organotin(IV) Complexes: Spectroscopic and Structural Studies of 2,6？Diacetylpyridine bis(thiosemicarbazone)di？n？butyltin(IV) Chloride Nitromethane Solvate, [nBu2Sn(H2daptsc)]Cl 2？MeNO2 and of 2,6？Diacetylpyridine bis(semicarbazone)dimethyltin(IV) trans？Tetrachlorodimethylstannate(IV), [Me2Sn(H2dapsc)][Me2 SnCl4]

two new cases of heptacoordination in organotin(iv) complexes are described. both possess pentagonal bipyramidal geometry and show the organic groups on the axial positions, with the ligands forming five bonds to tin(iv) on the equatorial plane. the first complex, [nbu2sn(h2daptsc)]cl2 ？meno2 (1) is entirely new, whereas the second, [me2sn(h2dapsc)][me2 sncl4] (2), although previously reported, only now had its structure determined. in both 1 and 2 the heptacoordinate species are cationic, but whereas in 1 the counterion is simply cl-, in 2 it is a complex anion, namely [me2sncl4]2.