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

Abstract

Abstract [(CH3)3Sn]2S2(C2N2S) is monoclinic, space group P21 /c, a = 10.492(5), b = 12.257(6), c = 12.691(6) Å, β = 95.86(1)°. 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 moieties, bound to the atom C5 of the heterocyclus, remains tetrahedral, whereas the other, bound to C2, is transformed through the N3 atom of the neighbouring ring to a trigonal bipyramid S···(Me3Sn)···N. The three C atoms and the Sn atom of this Me3Sn group are nearly coplanar and form the equatorial plane. With the N3 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 SN2 displacement at tetrahedrally coordinated tin.