Synthesis and X-ray crystal structures of six [TeL4][MF6] salts, where L is ethylene- or trimethylene-thiourea, and M is Si, Ge or Sn. Five Te(II) complexes with a novel type of structure linked together by unusual N–H⋯F hydrogen bonds
摘要:
The complexes [Te(etu)(4)][SiF6] (1), [Te(etu)(4)][SiF6] . H2O (2), [Te(trtu)(4)][SiF6] (3), [Te(etu)(4)][GeF6] . H2O (4), [Te(trtu)(4)][GeF6] (5) and [Te(etu)(4)][SnF6] (6) (etu = ethylenethiourea, trtu = trimethylenethiourea) have been prepared and their crystal structures determined by X-ray crystallographic methods. The crystals of 1, 3 and 5 are tetragonal; space groups P4cc (No. 103) with Z = 4 for 1, P4nc (No. 104) with Z = 2 for 3, and I4 (No. 79) with Z = 2 for 5. The crystals of 2, 4 and 6 are orthorhombic, space group Pccn (No. 56) with Z = 8 for 2 and 4 and Z = 4 for 6; those of 2 and 4 being isomorphous. The cations contain square planar or slightly distorted square planar TeS4 coordination groups. In 1, 3 and 5 the Te atoms are located on fourfold rotation axes; the cations have fourfold rotational symmetry and the four thiourea ligands extend to the same side of the TeS4 plane. These are the first examples of [TeL4](2+) conformers of this type. In 2 and 4 the Te atoms lie on general positions; the cations are distorted versions of those in 1, and also in these the four ligands extend to the same side of the TeS4 plane. In 6 the Te atoms are located on twofold rotation axes, the conformation of the cations corresponds to the point group C-2 with two neighbouring ligands extending to one side of the coordination plane and the remaining two to the opposite side. In 1-5 each of the four ligands forms a N-H...F bond to the same F atom in the counter ion. The crystals of 1-5 are red, and those of 6 are yellow. The red colour is attributed to interactions of Te and S lone electron pairs caused by ligand TeS4/TeSC tilt angles markedly different from 90degrees. (C) 2004 Elsevier Ltd. All rights reserved.