trans-Diaqua­bis­(1H-imidazole-4-carboxyl­ato-κ² N ³,O ⁴)nickel(II)

Abstract

In the title complex, [Ni(C₄H₃N₂O₂)₂(H₂O)₂], the Ni^II ion is located on an inversion center and shows a distorted octa­hedral geometry, defined by two N,O-bidentate 1H-imidazole-4-carboxyl­ate ligands in the equatorial plane and two water mol­ecules in the axial positions. Inter­molecular N—H⋯O hydrogen bonds link the complex mol­ecules into layers parallel to (10), which are further linked into a three-dimensional supra­molecular network through O—H⋯O hydrogen bonds.

Related literature

For general background to the design and synthesis of coordination polymers, see: Choi & Jeon (2003 ▶); Moulton & Zaworotko (2001 ▶); Roesky & Andruh (2003 ▶); Tao et al. (2000 ▶). For complexes with imidazole-4,5-dicarb­oxy­lic acid, see: Alkordi et al. (2009 ▶); Lu et al. (2009 ▶); Sun et al. (2005 ▶). For related structures, see: Gryz et al. (2007 ▶); Haggag (2005 ▶); Starosta & Leciejewicz (2006 ▶); Xu et al. (2008 ▶); Yin et al. (2009 ▶); Zheng et al. (2011 ▶).

Experimental

Crystal data

• [Ni(C₄H₃N₂O₂)₂(H₂O)₂]

• M _r = 316.91

• Monoclinic,

• a = 6.6123 (18) Å

• b = 12.267 (3) Å

• c = 7.239 (2) Å

• β = 101.059 (3)°

• V = 576.2 (3) ų

• Z = 2

• Mo Kα radiation

• μ = 1.72 mm⁻¹

• T = 298 K

• 0.48 × 0.36 × 0.32 mm

Data collection

• Bruker APEXII CCD diffractometer

• Absorption correction: multi-scan (SADABS; Sheldrick, 1996 ▶) T _min = 0.493, T _max = 0.610

• 2878 measured reflections

• 1043 independent reflections

• 947 reflections with I > 2σ(I)

• R _int = 0.027

Refinement

• R[F ² > 2σ(F ²)] = 0.027

• wR(F ²) = 0.070

• S = 1.07

• 1043 reflections

• 88 parameters

• H-atom parameters constrained

• Δρ_max = 0.25 e Å⁻³

• Δρ_min = −0.42 e Å⁻³

Data collection: APEX2 (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: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

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⋯O2i	0.86	2.16	2.942 (3)	152
N2—H2N⋯O1i	0.86	2.36	3.130 (2)	149
O1W—H1WA⋯O2ii	0.83	1.94	2.762 (2)	169
O1W—H1WB⋯O2iii	0.84	1.94	2.7654 (19)	168

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

supplementary crystallographic information

Comment

The rational design and synthesis of coordination polymers have received extensive attention over the past decades (Moulton & Zaworotko, 2001; Roesky & Andruh, 2003). The choice of suitable ligands is an important factor that greatly affects the structure and stabilization of the coordination architecture (Choi & Jeon, 2003; Tao et al., 2000). Recently, our group has focused on constructing coordination polymers based on N-heterocyclic carboxylic acids (Zheng et al., 2011). 1H-Imidazole-4-carboxylic acid (H₂imc), which is recognized as efficient N/O donors exhibiting versatile coordination behaviors and potential hydrogen-bonding abilities, remains largely unexplored, compared with its analogue imidazole-4,5-dicarboxylic acid (Alkordi et al., 2009; Lu et al., 2009; Sun et al., 2005). A few of mononuclear complexes based on the H₂imc ligand have been reported (Gryz et al., 2007; Haggag, 2005; Starosta & Leciejewicz, 2006; Yin et al., 2009). In this work, we report the synthesis and structure of a new Ni^II complex, which was obtained by the solvothermal reaction of Ni(ClO₄)₂.6H₂O and H₂imc.

The asymmetric unit contains a half of [Ni(Himc)₂(H₂O)₂] formula unit, with the Ni^II ion lying on an inversion center. The Ni^II ion exhibits a distorted octahedral geometry, in which two bidentate chelating Himc ligands are located in the equatorial plane, forming two stable five-membered rings with metal ion, and the axial sites are occupied by two coordinated water molecules (Fig. 1). The Ni—O distances range from 2.0764 (13) to 2.0947 (17) Å and Ni—N bonds have the value of 2.0502 (17) Å, which are similar to the reported Ni^II complexes with imidazole-based carboxylate ligands (Xu et al., 2008).

In the crystal, each complex molecule is joined to four adjacent ones via N2–H2···O1ⁱⁱ and N2–H2···O2ⁱⁱ hydrogen bonds between the imidazole N—H group and carboxylate O atoms (Table 1) [symmetry code: (ii) x + 1, -y + 1/2, z + 1/2], generating a two-dimensional hydrogen-bonded sheet parallel to (1 0 2) (Fig. 2). These sheets are further linked by O—H···O hydrogen bonds involving the coordinated water molecules (O1W) and carboxylate O atoms (O2), resulting in a three-dimensional supramolecular network (Fig. 3).

Experimental

A mixture of Ni(ClO₄)₂.6H₂O (41.9 mg, 0.10 mmol), H₂imc (11.2 mg, 0.10 mmol), NaOH (4.0 mg, 0.10 mmol) and EtOH/H2O (v/v 1:1, 6 ml) was sealed in a 10 ml Teflon-lined stainless-steel reactor, which was heated to 100°C for 48 h under autogenous pressure, and then slowly cooled to room temperature at a rate of 5°C h^-1. Pale green block crystals of the title compound were isolated, washed with distilled water and dried in air (yield: 78%). IR (KBr, cm^-1): 3340 s, 2923 m, 2853 w, 2350 w, 1598 s, 1461 m, 1427 w, 1402 w, 1357 m, 1287 w, 1260 w, 1091 s, 1039 m, 854 w, 806 w, 723 m, 655 w, 544 m, 456w.

Refinement

C– and N-bound H atoms were positioned geometrically and refined using a riding model, with C—H = 0.93 and N—H = 0.86 Å and with U_iso(H) = 1.2U_eq (C, N). H atoms of water molecule were located from a difference Fourier map and refined as riding atoms with O—H = 0.84 Å.

Figures

Fig. 1.

The molecular structure of the title compound, with displacement ellipsoids drawn at the 30% probability level. [Symmetry code: (i) 1 - x, -y, -z.]

Fig. 2.

The crystal packing of the title compound, showing the two-dimensional hydrogen-bonded network. Hydrogen bonds are shown as dashed lines. [Symmetry code: (ii) x + 1, -y + 1/2, z + 1/2.]

Fig. 3.

The crystal packing of the title compound, showing the three-dimensional hydrogen-bonded network. Hydrogen bonds are shown as dashed lines.

Crystal data

[Ni(C4H3N2O2)2(H2O)2]	F(000) = 324
Mr = 316.91	Dx = 1.826 Mg m−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 1803 reflections
a = 6.6123 (18) Å	θ = 3.1–27.8°
b = 12.267 (3) Å	µ = 1.72 mm−1
c = 7.239 (2) Å	T = 298 K
β = 101.059 (3)°	Block, pale green
V = 576.2 (3) Å3	0.48 × 0.36 × 0.32 mm
Z = 2

Data collection

Bruker APEXII CCD diffractometer	1043 independent reflections
Radiation source: fine-focus sealed tube	947 reflections with I > 2σ(I)
graphite	Rint = 0.027
φ and ω scans	θmax = 25.2°, θmin = 3.1°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −7→7
Tmin = 0.493, Tmax = 0.610	k = −14→14
2878 measured reflections	l = −8→7

Refinement

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.027	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.070	H-atom parameters constrained
S = 1.07	w = 1/[σ2(Fo2) + (0.0415P)2 + 0.1301P] where P = (Fo2 + 2Fc2)/3
1043 reflections	(Δ/σ)max < 0.001
88 parameters	Δρmax = 0.25 e Å−3
0 restraints	Δρmin = −0.42 e Å−3

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
Ni1	0.5000	0.0000	0.0000	0.02288 (16)
N1	0.7437 (3)	0.09727 (13)	0.1157 (2)	0.0289 (4)
C3	0.8498 (3)	0.26678 (17)	0.1929 (3)	0.0331 (5)
H2	0.8537	0.3422	0.2070	0.040*
C4	0.9370 (3)	0.09539 (18)	0.2052 (3)	0.0401 (6)
H4	1.0157	0.0325	0.2312	0.048*
C2	0.6866 (3)	0.20552 (15)	0.1070 (3)	0.0226 (4)
N2	1.0046 (3)	0.19580 (17)	0.2536 (3)	0.0411 (5)
H2N	1.1260	0.2125	0.3132	0.049*
O2	0.4160 (2)	0.32925 (10)	−0.0090 (2)	0.0322 (4)
O1	0.3604 (2)	0.15166 (10)	−0.0480 (2)	0.0270 (3)
O1W	0.4100 (3)	−0.00996 (9)	0.2616 (2)	0.0307 (4)
C1	0.4750 (3)	0.23191 (17)	0.0111 (2)	0.0225 (4)
H1WA	0.4644	−0.0632	0.3236	0.027*
H1WB	0.4254	0.0483	0.3241	0.027*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Ni1	0.0221 (3)	0.0146 (2)	0.0284 (2)	0.00075 (12)	−0.00422 (15)	−0.00212 (12)
N1	0.0249 (10)	0.0224 (9)	0.0348 (9)	0.0037 (7)	−0.0057 (7)	−0.0029 (7)
C3	0.0268 (11)	0.0294 (11)	0.0410 (12)	−0.0075 (9)	0.0013 (9)	−0.0092 (9)
C4	0.0267 (13)	0.0401 (13)	0.0473 (13)	0.0096 (10)	−0.0089 (10)	−0.0050 (10)
C2	0.0213 (10)	0.0200 (9)	0.0249 (9)	−0.0018 (7)	−0.0001 (8)	−0.0020 (7)
N2	0.0179 (9)	0.0548 (12)	0.0455 (11)	−0.0031 (8)	−0.0066 (8)	−0.0147 (9)
O2	0.0348 (9)	0.0188 (7)	0.0385 (9)	0.0048 (6)	−0.0037 (6)	0.0020 (5)
O1	0.0211 (7)	0.0199 (7)	0.0348 (7)	0.0010 (6)	−0.0076 (6)	−0.0025 (6)
O1W	0.0403 (10)	0.0188 (7)	0.0306 (8)	0.0027 (6)	0.0008 (7)	−0.0008 (5)
C1	0.0243 (11)	0.0214 (11)	0.0204 (9)	0.0008 (7)	0.0008 (8)	0.0003 (7)

Geometric parameters (Å, °)

Ni1—N1	2.0502 (17)	C4—N2	1.334 (3)
Ni1—O1	2.0764 (13)	C4—H4	0.9300
Ni1—O1W	2.0947 (17)	C2—C1	1.473 (3)
N1—C4	1.318 (3)	N2—H2N	0.8600
N1—C2	1.379 (3)	O2—C1	1.256 (2)
C3—N2	1.352 (3)	O1—C1	1.266 (2)
C3—C2	1.363 (3)	O1W—H1WA	0.83
C3—H2	0.9300	O1W—H1WB	0.84
N1i—Ni1—N1	180.00 (10)	N2—C3—H2	127.0
N1i—Ni1—O1i	80.58 (6)	C2—C3—H2	127.0
N1—Ni1—O1i	99.42 (6)	N1—C4—N2	110.96 (19)
N1i—Ni1—O1	99.42 (6)	N1—C4—H4	124.5
N1—Ni1—O1	80.58 (6)	N2—C4—H4	124.5
O1i—Ni1—O1	180.00 (8)	C3—C2—N1	108.92 (18)
N1i—Ni1—O1Wi	90.11 (7)	C3—C2—C1	133.68 (19)
N1—Ni1—O1Wi	89.89 (7)	N1—C2—C1	117.39 (16)
O1i—Ni1—O1Wi	90.53 (5)	C4—N2—C3	108.32 (18)
O1—Ni1—O1Wi	89.47 (5)	C4—N2—H2N	125.8
N1i—Ni1—O1W	89.89 (7)	C3—N2—H2N	125.8
N1—Ni1—O1W	90.11 (7)	C1—O1—Ni1	114.94 (12)
O1i—Ni1—O1W	89.47 (5)	Ni1—O1W—H1WA	111.4
O1—Ni1—O1W	90.53 (5)	Ni1—O1W—H1WB	114.2
O1Wi—Ni1—O1W	180.00 (11)	H1WA—O1W—H1WB	112.4
C4—N1—C2	105.70 (17)	O2—C1—O1	123.19 (17)
C4—N1—Ni1	143.40 (15)	O2—C1—C2	120.62 (18)
C2—N1—Ni1	110.80 (13)	O1—C1—C2	116.20 (17)
N2—C3—C2	106.10 (18)
O1i—Ni1—N1—C4	−2.4 (3)	C4—N1—C2—C1	179.45 (17)
O1—Ni1—N1—C4	177.6 (3)	Ni1—N1—C2—C1	−3.3 (2)
O1Wi—Ni1—N1—C4	−92.9 (3)	N1—C4—N2—C3	−0.2 (3)
O1W—Ni1—N1—C4	87.1 (3)	C2—C3—N2—C4	0.2 (2)
O1i—Ni1—N1—C2	−177.92 (12)	N1i—Ni1—O1—C1	179.42 (13)
O1—Ni1—N1—C2	2.08 (12)	N1—Ni1—O1—C1	−0.58 (13)
O1Wi—Ni1—N1—C2	91.56 (13)	O1Wi—Ni1—O1—C1	−90.55 (13)
O1W—Ni1—N1—C2	−88.44 (13)	O1W—Ni1—O1—C1	89.45 (13)
C2—N1—C4—N2	0.2 (2)	Ni1—O1—C1—O2	178.85 (13)
Ni1—N1—C4—N2	−175.53 (18)	Ni1—O1—C1—C2	−1.03 (19)
N2—C3—C2—N1	−0.1 (2)	C3—C2—C1—O2	2.5 (3)
N2—C3—C2—C1	−179.5 (2)	N1—C2—C1—O2	−176.88 (16)
C4—N1—C2—C3	0.0 (2)	C3—C2—C1—O1	−177.7 (2)
Ni1—N1—C2—C3	177.21 (13)	N1—C2—C1—O1	3.0 (2)

Symmetry codes: (i) −x+1, −y, −z.

Hydrogen-bond geometry (Å, °)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H2N···O2ii	0.86	2.16	2.942 (3)	152
N2—H2N···O1ii	0.86	2.36	3.130 (2)	149
O1W—H1WA···O2iii	0.83	1.94	2.762 (2)	169
O1W—H1WB···O2iv	0.84	1.94	2.7654 (19)	168

Symmetry codes: (ii) x+1, −y+1/2, z+1/2; (iii) −x+1, y−1/2, −z+1/2; (iv) x, −y+1/2, z+1/2.