Acta Crystallographica Section C

Crystal Structure Communications

Volume 64, Part 5 (May 2008)

metal-organic compounds

 

Zinc(II) and cadmium(II) chloride complexes with 4,4'-bi-1,2,4-triazole

E. V. Govor, A. B. Lysenko and K. V. Domasevitch

Abstract: New coordination compounds with the 4,4'-bi-1,2,4-triazole ligand (btr), namely tetraaqua-2⁴O-di-₂-4,4'-bi-1,2,4-triazole-1:2²N¹:N^1';2:3²N¹:N^1'-hexachlorido-1³Cl,3³Cl-trizinc(II), [Zn₃Cl₆(C₄H₄N₆)₂(H₂O)₄], (I), and poly[cadmium(II)-₂-4,4'-bi-1,2,4-triazole-²N¹:N²-di-₂-chlorido], [CdCl₂(C₄H₄N₆)]_n, (II), reveal an unprecedented molecular zwitterionic structure for (I) and a polymeric two-dimensional layer structure for (II). Differences between these products, which involve the formation of either charge-separated chlorometallate/aquametal fragments or complementary organic and inorganic bridges, are attributable to the hardness-softness characters of the metal cations. In (I), two N¹,N^1'-bidentate btr molecules connect one [Zn(H₂O)₄]²⁺ cation and two [ZnCl₃]^- anions into a linear trizinc motif (the Zn atom of the cation occupies a centre of inversion in an N₂O₄ coordination octahedron, whereas the Zn atom of the anion possesses a distorted tetrahedral Cl₃N environment). In (II), the distorted vertex-sharing CdCl₄N₂ octahedra are linked into binuclear [Cd₂(₂-Cl)(₂-btr)₂]³⁺ fragments by unprecedented N¹:N²-bidentate btr double bridges and bridging chloride ligands, while the additional chloride anions are also bridging, providing further propagation of the fragments into a two-dimensional network [Cd-Cl = 2.5869 (2)-2.6248 (7) Å].

Formula: [Zn₃Cl₆(C₄H₄N₆)₂(H₂O)₄] and [CdCl₂(C₄H₄N₆)]

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