A new β-octa­molybdate(VI) salt based on 1,4-bis­(2-methyl-1H-imidazol-1-yl)butane

Shun-Li Li; Ke Tan

doi:10.1107/S1600536808035022

. 2008 Nov 8;64(Pt 12):m1487. doi: 10.1107/S1600536808035022

A new β-octamolybdate(VI) salt based on 1,4-bis(2-methyl-1H-imidazol-1-yl)butane

Shun-Li Li ^a,^*, Ke Tan ^b

PMCID: PMC2960135 PMID: 21581111

Abstract

The title compound, bis[2,2′-dimethyl-3,3′-(butane-1,4-diyl)diimidazol-1-ium] β-octamolybdate(VI), (C₁₂H₂₀N₄)₂[Mo₈O₂₆], was produced by hydrothermal reaction of an acidified aqueous solution of Na₂MoO₄ and 1,4-bis(2-methyl-1H-imidazol-1-yl)butane (hereafter L). The structure of the title compound consists of the β-octamolybdate anions having a center of symmetry, and protonated [H₂ L]²⁺ cations, which link the β-octamolybdate anions, generating a supramolecular chain via hydrogen bonds.

Related literature

For the applications of polyoxometalates (POMs) chemistry, see: Kozhevnikov (1998 ▶); Rhule et al. (1998 ▶); Li et al. (2007 ▶). For the coordination ability of polyoxometalates with different transition-metal organic units, see: Hagrman et al. (1997 ▶); Li et al. (2008 ▶). For the introduction of POMs into coordination polymers for the construction of polymers with desired properties, see: Bu et al. (2001 ▶); Wu et al. (2002 ▶).

Experimental

Crystal data

(C₁₂H₂₀N₄)₂[Mo₈O₂₆]
M _r = 1624.16
Triclinic,
a = 10.5680 (3) Å
b = 11.4890 (5) Å
c = 11.5600 (8) Å
α = 60.7770 (10)°
β = 68.1550 (10)°
γ = 70.4000 (10)°
V = 1116.29 (10) Å³
Z = 1
Mo Kα radiation
μ = 2.27 mm⁻¹
T = 293 (2) K
0.27 × 0.26 × 0.20 mm

Data collection

Bruker APEX CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.49, T _max = 0.63
6962 measured reflections
5123 independent reflections
3776 reflections with I > 2σ(I)
R _int = 0.016

Refinement

R[F ² > 2σ(F ²)] = 0.032
wR(F ²) = 0.079
S = 1.04
5123 reflections
306 parameters
2 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.53 e Å⁻³
Δρ_min = −0.71 e Å⁻³

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

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808035022/bg2208sup1.cif

e-64-m1487-sup1.cif^{(30.7KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808035022/bg2208Isup2.hkl

e-64-m1487-Isup2.hkl^{(245.8KB, hkl)}

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

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N2—H2N⋯O9ⁱ	0.87 (3)	2.37 (4)	3.031 (5)	134 (4)
N2—H2N⋯O10ⁱ	0.87 (3)	2.20 (2)	3.001 (5)	153 (5)
N4—H4N⋯O12ⁱⁱ	0.86 (3)	2.39 (4)	3.052 (5)	134 (4)
N4—H4N⋯O4ⁱⁱⁱ	0.86 (3)	2.12 (3)	2.873 (4)	146 (5)

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) .

supplementary crystallographic information

Comment

Polyoxometalates (POMs), a unique class of metal-oxide clusters, have many properties that make them attractive for applications in catalysis, biology, magnetism, optics, medicine, etc (Kozhevnikov, 1998; Rhule et al., 1998; Li et al., 2007). In recent times a remarkable approach to the construction of multifunctional materials is being realized exploting the ability of polyoxometalates to coordinate to different transition-metal organic units (Hagrman et al., 1997; Li et al., 2008). The POMs, acting as unusual inorganic ligands are introduced into a variety of POM-based coordination polymers with desired properties (Bu et al., 2001; Wu et al., 2002). During our ongoing studies of related materials, we obtained the title compound, (I), and present its crystal structure here.

The asymmetric unit of compound (I) contains a complete (C₁₂H₂₀N₄²⁺) cation (hereafter [H₂L]²⁺) and half a [Mo₈O₂₆]^4- anion. The complete [Mo₈O₂₆]^4- moiety is generated from the asymmetric unit atoms by a crystallographic inversion center (Fig. 1). It consists of eight edge-sharing MoO₆ octahedra and displays the characteristic β-octamolybdate arrangement. Each protonated [H₂L]²⁺ cation donates two N—H···O hydrogen bonds to two terminal oxygen atoms from one [Mo₈O₂₆]^4- anion and two ones to two bridging oxygen atoms from the other [Mo₈O₂₆]^4- anion. So each [Mo₈O₂₆]^4- anion joins four protonated [H₂L]²⁺ cations (see the hydrogen bonding table for numerical values) to generate a one-dimensional supramolecular double-chain structure (Fig. 2).

Experimental

A mixture of Na₂MoO₄.2H₂O (0.242 g, 1.0 mmol) and L (0.218 g, 1.0 mmol) in water (10 ml) was adjusted with HCl (2M) to pH = 3. Then the mixture was placed in a 23 ml Teflon-lined autoclave and kept under autogenous pressure at 150 °C for 2 days. After the mixture was cooled to room temperature at 10°C.h^-1, colorless crystals of the title compound were obtained.