Bis(cyanato-κN)bis­(5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine-κN 3)zinc

Ana B Caballero; Miguel Quirós; Antonio Rodríguez-Diéguez; Juan M Salas

doi:10.1107/S1600536811005769

. 2011 Feb 19;67(Pt 3):m345. doi: 10.1107/S1600536811005769

Bis(cyanato-κN)bis(5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine-κN ³)zinc

Ana B Caballero ^a,^*, Miguel Quirós ^a, Antonio Rodríguez-Diéguez ^a, Juan M Salas ^a

PMCID: PMC3052141 PMID: 21522274

Abstract

In the title complex, [Zn(NCO)₂(C₇H₈N₄)₂], the Zn^II ion exhibits a distorted tetrahedral coordination geometry. The coordination environment is formed by two 5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine (dmtp) ligands, coordinated through the N atom in position 3, and two cyanate anions interacting by their N atoms. Supramolecular dimers are generated by stacking interactions between the pyrimidine rings of two ligands related by an inversion center [centroid–centroid distance = 3.5444 (18) Å].

Related literature

For similar structures, see: Adriaanse et al. (2009 ▶); Salas et al. (1999 ▶); Caballero et al. (2010 ▶). For a description of the geometry of tetrahedrally coordinated metal atoms, see: Yang et al. (2007 ▶).

Experimental

Crystal data

[Zn(NCO)₂(C₇H₈N₄)₂]
M _r = 445.76
Triclinic,
a = 10.0023 (15) Å
b = 10.8168 (16) Å
c = 11.1094 (16) Å
α = 116.772 (2)°
β = 107.226 (2)°
γ = 98.557 (2)°
V = 967.2 (2) Å³
Z = 2
Mo Kα radiation
μ = 1.31 mm⁻¹
T = 293 K
0.25 × 0.14 × 0.10 mm

Data collection

Bruker SMART APEX CCD system diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.773, T _max = 0.881
11387 measured reflections
4403 independent reflections
3580 reflections with I > 2σ(I)
R _int = 0.025

Refinement

R[F ² > 2σ(F ²)] = 0.039
wR(F ²) = 0.106
S = 1.01
4403 reflections
266 parameters
H-atom parameters constrained
Δρ_max = 0.37 e Å⁻³
Δρ_min = −0.22 e Å⁻³

Data collection: SMART (Bruker, 2007 ▶); cell refinement: SAINT (Bruker, 2007 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: Xtal_GX (Hall et al., 1999 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536811005769/su2253sup1.cif

e-67-0m345-sup1.cif^{(18.7KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811005769/su2253Isup2.hkl

e-67-0m345-Isup2.hkl^{(215.7KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

Financial support from the Junta de Andalucia (FQM-3705 and FQM-4228) and the Spanish Ministry of Education (FPU fellowship of Ana B. Caballero) is gratefully acknowledged.

supplementary crystallographic information

Comment

The coordination chemistry of 1,2,4-triazolo[1,5-a]pyrimidine derivatives displays great versatility, binding metal ions in several different ways, either in a monodentate (usually through the N atom in position 3) or in a bidentate fashion, bridging metal atoms and leading to dinuclear or polynuclear species with interesting metal-metal interactions (Salas et al., 1999). Some zinc(II) complexes containing these derivatives together with secondary bridging ligands have been described, for example with the thiocyanate anion (Salas et al., 1999; Adriaanse et al., 2009). In most of these metal complexes, both ligands display monodentate binding leading to mononuclear species with either octahedral or tetrahedral coordination geometries.

The title compound continues our studies on a series of triazolopyrimidine and pseudohalide-based metal complexes (Caballero et al., 2010). This zinc(II) complex, together with the analogous complex with the unsubstituted triazolopyrimidine ligand (Caballero et al., 2010), are the only ones that have been obtained with the cyanate anion.

The title compound exhibits a distorted tetrahedral coordination geometry (τ₄ = 0.924, Yang et al., 2007) made of two dmtp ligands (dmtp = 5,7-dimethyl-1,2,4-triazolo[1,5-a]pyrimidine) interacting through their more usual coordination position, N3, and two cyanate anions bound through their N atom (Fig. 1). The Zn—N3 bond distances, 2.022 (2) and 2.043 (2) Å, are in the typical range for triazolopyrimidine ligands.

In the crystal the stacking interactions between the pyrimidine ring of two triazolopyrimidine aromatic systems leads to the formation of supramolecular centrosymmetric dimers (Fig. 2); the centroid-to-centroid distance, involving ring (N4A,C3A,N8A,C7A,C6A,C5A) and that related by an inversion center [symmetry code: 1-x, -y, -z], is 3.5444 (18) Å.

Experimental

A 10 ml volume of an aqueous solution containing 1 mmol of NaNCO (0.068 g) was slowly added to a 10 ml aqueous solution containing 0.5 mmol of Zn(NO)₃.4H₂O (0.131 g) and 1 mmol of dmtp ligand (0.148 g). Immediately after adding NaNCO, a yellow turbidity gradually appeared. The mixture was stirred at 353 K for 15 min. and the precipitate was then filtered off. The resulting clear yellow solution was left to stand for a week at room temperature and yellow crystals of the title compound were collected and used for X-ray diffraction studies.