The crystal structure of “bis(trimethyltin)-1,3,4-thiadiazole-2,5-dithiolate” – different bonding of the two trimethyltin groups

[(CH3)(3)Sn](2)S-2(C2N2S) is monoclinic, space group P2(1)/c, a = 10.492(5), b = 12.257(6), c = 12.691(6) angstrom, beta = 95.86(1)degrees. The zigzag chain structure of the coordination polymer can be derived by the structure correlation method. The starting point is a monomolecular symmetric bis(trimethyltin)-1,3,4-thiadiazole-2,5-dithiolate (Me3SnS)(2)(C2N2S): The first of the Me3SnS rnoieties, bound to the atom C-5 of the heterocyclus, remains tetrahedral, whereas the other, bound to C-2, is transformed through the N-3 atom of the neighbouring ring to a trigonal bipyramid S...(Me3Sn)...N. The three C atoms and the Sri atom of this Me3Sn group are nearly coplanar and form the equatorial plane. With the N-3 atom of the starting molecule, an equivalent linking to the other neighbour takes place. The resultant plane ribbons run parallel to the crystallographic b-axis. The analysis of the bond distances and angles reveals that the regular trigonal bipyramid almost exactly represents the transition state along a chemical reaction pathway for a nucleophilic S(N)2 displacement at tetrahedrally coordinated tin.