Multidimensional transition metal complexes based on 3-amino-1H-1,2,4-triazole-5-carboxylic acid: from discrete mononuclear complexes to layered materials

Abstract

The synthesis and structural characterization of five transition metal complexes with different dimensionality and incorporating residues of 3-amino-1H-1,2,4-triazole-5-carboxylic acid (H2atrc) is reported: [Zn(Hatrc)2(H2O)] (1), [Mn(Hatrc)2(H2O)2]·2H2O (2), [Fe2(Hatrc)4(OH)2]·6H2O (3), [Cd(Hatrc)2(H2O)]n (4), and [Mn(atrc)(H2O)]n·nH2O (5). These materials could be prepared from solution (1-3), diffusion (4), or hydrothermal reactions (5) with various anions and L:M ratios. Structural details were revealed by single crystal X-ray diffraction. The discrete units composing compounds 1-3, the polymeric 1D chain of 4 and the 2D layer of 5 are further extended into 3D supramolecular architectures through the formation of hydrogen bonds.

Keywords: 1,2,4-triazole; crystal structures; supramolecular organization.

Scheme 1

Coordination modes of Hatrc⁻ (type I and II) and atrc²⁻ (type III) anionic residues found in compounds 1–5.

Figure 1

Schematic representation of the mononuclear complex [Zn(Hatrc)₂(H₂O)] present in compound 1, showing the labelling scheme for all non-H atoms composing the asu and those forming the metal coordination sphere. Non-H atoms of the asu are drawn as thermal ellipsoids at the 30% probability level and the remaining atoms as spheres with arbitrary radius. For selected bond lengths and angles see Table 1. Symmetry transformation: a = 1−x, y, 1.5−z.

Figure 2

Ball-and-stick representation of (a) the 2D hydrogen-bonded network and (b) 3D hydrogen-bonded supramolecular network (layers with alternating colors) in the crystal structure of compound 1. Hydrogen bonds are represented as yellow (those forming the 2D network) and orange (inter-layer connections) dashed lines. Geometric details on the represented interactions are listed in Table 2.

Figure 3

Mononuclear anionic complex [Mn(Hatrc)₂(H₂O)₂] found in 2 showing the labelling scheme for all non-H atoms composing the asu and the metallic coordination environment. Crystallographically independent non-H atoms are represented as thermal ellipsoids drawn at the 50% probability level. Symmetry-related atoms are represented as spheres with arbitrary radius. For selected bond lengths and angles see Table 1. Symmetry operation: b = 1−x, 1−y, 1−z.

Figure 4

Ball-and-stick representation of (a) the 1D hydrogen-bonded chain; (b) the 2D layer and (c) the 3D supramolecular network (layers alternating between original and green color) present in compound 2. Hydrogen bonds are represented by dashed light-green lines. For details on the represented interactions see Table 2.

Figure 5

Representation of the binuclear complex [Fe₂(Hatrc)₄(OH)₂] present in compound 3, showing the labelling scheme for all non-H atoms composing the asu and the Fe1 coordination environment. Non-H atoms of the asu are represented as thermal ellipsoids (70% probability level) and the remaining atoms as spheres with arbitrary radii. For selected bond lengths and angles see Table 3. Symmetry operation: l = x, 0.5−y, 0.5−z.

Figure 6

Ball-and-stick representation of the 2D hydrogen-bonded layer present in compound 3 viewed along the (a) [001] and (b) [100] directions of the unit cell (1D supramolecular chains represented in alternate colors); (c) Perspective view of the 3D supramolecular framework (layers alternate between colors) present in the crystal structure of 3. Dashed yellow lines represent the hydrogen bonds. Geometric details on these supramolecular interactions are summarized in Table 4.

Figure 7

Schematic representation of the (a) Cd²⁺ coordination environment present in compound [Cd(Hatrc)₂(H₂O)]_n (4) showing the labeling scheme for all non-hydrogen atoms composing the asu and the Cd1 coordination environment. Non-H atoms of the asu are represented as thermal ellipsoids drawn at the 70% probability level and the remaining atoms as spheres with arbitrary radii; (b) 1D coordination chain present in compound 4. For selected bond lengths (in Å) and angles (in degrees) see Table 3. Symmetry operation: m = 1.5−x, y+0.5, 0.5−z.

Figure 7

Schematic representation of the (a) Cd²⁺ coordination environment present in compound [Cd(Hatrc)₂(H₂O)]_n (4) showing the labeling scheme for all non-hydrogen atoms composing the asu and the Cd1 coordination environment. Non-H atoms of the asu are represented as thermal ellipsoids drawn at the 70% probability level and the remaining atoms as spheres with arbitrary radii; (b) 1D coordination chain present in compound 4. For selected bond lengths (in Å) and angles (in degrees) see Table 3. Symmetry operation: m = 1.5−x, y+0.5, 0.5−z.

Figure 8

Ball-and-stick representation of the (a) 2D hydrogen-bonded network formed between adjacent 1D coordination chains (represented with alternating colors) and the (b) 3D hydrogen-bonded supramolecular network viewed in perspective along the [010] direction of the unit cell (layers represented with alternating colors) present in compound 4. Hydrogen bonds are represented as dashed yellow lines. Geometric details on these interactions are summarized in Table 5.

Figure 9

Mixed ellipsoid and ball-and-stick representation of the Mn²⁺ coordination environment present in compound [Mn(atrc)(H₂O)]·H₂O (5), showing the labeling scheme for all non-H atoms composing the asu and the first metal coordination sphere. Non-H atoms of the asu are represented as thermal ellipsoids drawn at the 90% probability level and the remaining atoms as spheres with arbitrary radius. For selected bond lengths and angles see Table 3. Symmetry operations: n = −x, 0.5+y, 0.5−z; o = x, 0.5−y, −0.5+z.

Figure 10

Ball-and-stick representation of (a) the 2D coordination layer and (b) 3D hydrogen-bonded network viewed along the [001] direction of the unit cell of compound 5 (layers represented with alternating colors). Hydrogen bonds are represented as dashed light-green lines. Geometric details on the represented supramolecular interactions are listed in Table 5.