Interpenetrating nets in cis-bis­(pyri­dine-4-carboxyl­ate)­nickel(II)

The title compound, [Ni(C₆H₄NO₂)₂], crystallized in a three-dimensional framework consisting of three interpenetrating diamond-like nets. The Ni atom is on a twofold axis, the coordination is `(O₂)₂N₂' in a cis arrangement and the ligands are bridging.

S1. Comment

Molecules containing bifunctional and multi-functional pyridine or carboxylate groups, such as 4,4'-bipyridine (Fujita et al., 1994; Stang et al., 1995; Yaghi & Li, 1995; Kondo et al., 1997; Hagrman et al., 1997; Kumar et al., 1998; Keller & Lopez, 1999; Biradha et al., 1999; Gudbjartson et al., 1999; Zhang et al., 1999), benzene-1,4-dicarboxylate (Eddaoudi et al., 2001; Groeneman et al., 1998; Guilera & Steed, 1999; Lo et al., 2000), pyridine-4-carboxylate (pyca) (MacGillivary et al., 1998; Evans, et al., 1999; Evans, Xiong et al., 1999; Ma et al., 1999; Evans & Lin, 2000), benzene-1,3,5-tricarboxylate (Chui et al., 1999; Chen et al., 2001; Choi & Suh, 1998) and other bridging molecules (Batten & Robson, 1998; Batten, 2001; Leininger et al., 2000; Fujita et al., 2001; Yaghi et al., 1998) are often used as ligands to construct coordination polymers with different nanostructures and interpenetrating nets. Diamond-related nets constitute the largest class of interpenetrating structures and most of these involve Zn^II, Cd^II, Cu^I and Ag^I metals (Batten & Robson, 1998). So far, no diamond-like net arrangement has been reported with Ni^II as the transition metal (Allen et al., 1983).

The Ni^II in (I) is six-coordinated by two cis-pyridyl N atoms of two µ-pyca anions and two chelating carboxylate groups of two additional µ-pyca anions (Fig. 1). The two Ni—O bond distances of the chelating µ-pyca anion are significantly different. One [Ni1—O2 2.074 (3) Å] is significantly longer than the Ni—N bond distance [Ni1—N1 2.041 (3) Å], and the other [Ni1—O1 2.208 (2) Å] is much longer. The angles around the Ni^II ion are also very different. The O1—Ni1—O2 and N1_8—Ni1—O1 angles are 61.88 (9) and 156.06 (10)°, respectively, while the other angles are closer to 90° [88.22 (10)–100.65 (15)°] and 180° [166.71 (14)°]; thus, the octahedral geometry of the Ni^II ion is highly distorted. The pyca ligand is not planar and has a dihedral angle of 19.5 (2)° between the planes defined by the carboxylate group and the pyridine moiety.

The extended arrangement consists of each Ni^II connected with four neighboring Ni^II ions through pyca bridges forming a three-dimensional diamond-like net (Fig. 2). Three independent three-dimensional diamond-like nets interpenetrate with each other (Fig. 3). The Ni to Ni atom separation in each three-dimensional net is 8.760 (5) Å.

S2. Experimental

A mixture of Eu₂O₃ (0.088 g, 0.25 mmol), NiCl₂·6H₂O (0.119 g, 0.5 mmol), pyridine-4-carboxylic acid (0.246 g, 0.2 mmol) and water (15 ml) was sealed in a 35 ml Teflon-capped ace pressure tube, heated to 453 K and held at that temperature for 12 h. During this time, the solid Eu₂O₃ dissolved completely and deep-green crystals of (I) (10% based on nickel) formed at the bottom of the tube. When the tube was cooled to room temperature, blue crystals of trans-tetraaquabis(pyridine-4-carboxylate-κN)nickel(II) (Batten & Harris, 2001) (40% based on nickel) formed. These were mechanically separated from the green crystals under a microscope. In this reaction, the Eu₂O₃ compound is presumably acting as a weak base. If the reaction temperature is below 413 K, only trans-tetraaquabis(pyridine-4-carboxylate-κN)nickel(II) is obtained (Batten & Harris, 2001). This suggests that the formation of the highly distorted structure in (I) requires more vigorous reaction conditions.

S3. Refinement

H atoms were treated as riding, with C—H distances of 0.93 Å and isotropic displacement parameters set to 1.2 times the equivalent isotropic displacement parameter of the C atoms to which they were attached.

Computing details

Data collection: CAD-4 EXPRESS (Enraf-Nonius, 1994); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).

Figures

	Fig. 1. ORTEP-3 (Farrugia, 1997) view of (I) shown with 50% probability displacement ellipsoids.
	Fig. 2. The three-dimensional framework of (I).
	Fig. 3. Stereoview of (I) using the Ni, C1 and N1 atoms connected by lines displaying the threefold interpenetrating diamond-like nets.

(I)

Crystal data

[Ni(C6H4NO2)2]	Dx = 1.703 Mg m^−3
Mr = 302.90	Mo Kα radiation, λ = 0.71069 Å
Tetragonal, P43212	Cell parameters from 25 reflections
a = 11.678 (3) Å	θ = 10–15°
c = 8.6608 (12) Å	µ = 1.65 mm^−1
V = 1181.1 (4) Å^3	T = 293 K
Z = 4	Prism, green
F(000) = 616	0.50 × 0.45 × 0.40 mm

Data collection

Enraf-Nonius CAD-4 diffractometer	Rint = 0.04
non–profiled ω/2θ scans	θmax = 25.0°, θmin = 2.5°
Absorption correction: ψ scan (North et al., 1968)	h = 0→13
Tmin = 0.451, Tmax = 0.516	k = 0→13
1448 measured reflections	l = −1→10
1043 independent reflections	3 standard reflections every 166 min
1021 reflections with I > 2σ(I)	intensity decay: 1%

Refinement

Refinement on F^2	H-atom parameters constrained
Least-squares matrix: full	w = 1/[σ^2(Fo^2) + (0.0667P)^2 + 0.3267P] where P = (Fo^2 + 2Fc^2)/3
R[F^2 > 2σ(F^2)] = 0.029	(Δ/σ)max = 0.003
wR(F^2) = 0.092	Δρmax = 0.29 e Å^−3
S = 1.18	Δρmin = −0.37 e Å^−3
1043 reflections	Absolute structure: (Flack, 1983), 327 Friedel pairs
87 parameters	Absolute structure parameter: 0.01 (3)
0 restraints

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

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

	x	y	z	Uiso*/Ueq
Ni1	0.22114 (3)	0.22114 (3)	0.5	0.0195 (2)
O1	0.1316 (2)	0.1257 (2)	0.3159 (3)	0.0302 (5)
O2	0.1041 (2)	0.3091 (2)	0.3643 (3)	0.0300 (5)
N1	−0.1474 (2)	0.2525 (2)	−0.0989 (3)	0.0249 (6)
C1	0.0862 (3)	0.2208 (3)	0.2831 (3)	0.0251 (7)
C2	0.0077 (3)	0.2309 (3)	0.1439 (4)	0.0245 (7)
C3	−0.0441 (3)	0.1351 (3)	0.0806 (4)	0.0274 (7)
H3	−0.028	0.0624	0.1187	0.033*
C4	−0.1210 (3)	0.1493 (3)	−0.0414 (4)	0.0261 (7)
H4	−0.1551	0.0848	−0.0843	0.031*
C5	−0.0938 (3)	0.3448 (3)	−0.0400 (4)	0.0296 (7)
H5	−0.1091	0.4163	−0.0825	0.036*
C6	−0.0163 (3)	0.3377 (3)	0.0821 (4)	0.0301 (7)
H6	0.0185	0.4032	0.1211	0.036*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Ni1	0.0208 (2)	0.0208 (2)	0.0169 (3)	−0.00097 (18)	−0.00042 (15)	0.00042 (15)
O1	0.0311 (14)	0.0280 (13)	0.0315 (11)	0.0010 (8)	−0.0104 (10)	0.0049 (10)
O2	0.0346 (12)	0.0306 (13)	0.0250 (11)	0.0030 (10)	−0.0083 (11)	−0.0051 (10)
N1	0.0252 (12)	0.0260 (14)	0.0234 (13)	−0.0002 (10)	−0.0028 (11)	−0.0009 (11)
C1	0.0224 (14)	0.0317 (16)	0.0212 (15)	−0.0030 (12)	0.0001 (12)	0.0041 (14)
C2	0.0230 (14)	0.0274 (16)	0.0232 (14)	0.0025 (12)	−0.0020 (13)	−0.0002 (13)
C3	0.0318 (17)	0.0252 (15)	0.0251 (15)	0.0041 (13)	−0.0024 (14)	0.0020 (14)
C4	0.0301 (17)	0.0217 (15)	0.0265 (17)	−0.0001 (12)	−0.0045 (12)	−0.0018 (13)
C5	0.0361 (17)	0.0211 (15)	0.0318 (17)	0.0010 (12)	−0.0070 (15)	0.0024 (13)
C6	0.0317 (17)	0.0248 (15)	0.0339 (17)	−0.0029 (14)	−0.0084 (15)	−0.0005 (13)

Geometric parameters (Å, º)

Ni1—N1^i	2.041 (3)	N1—C5	1.347 (4)
Ni1—N1^ii	2.041 (3)	N1—Ni1^iv	2.041 (3)
Ni1—O2	2.074 (2)	C1—C2	1.519 (4)
Ni1—O2^iii	2.074 (2)	C2—C3	1.385 (5)
Ni1—O1	2.208 (2)	C2—C6	1.386 (4)
Ni1—O1^iii	2.208 (2)	C3—C4	1.396 (4)
Ni1—C1	2.452 (3)	C3—H3	0.93
Ni1—C1^iii	2.452 (3)	C4—H4	0.93
O1—C1	1.263 (4)	C5—C6	1.393 (4)
O2—C1	1.265 (4)	C5—H5	0.93
N1—C4	1.340 (4)	C6—H6	0.93
N1^i—Ni1—N1^ii	100.65 (15)	C1—Ni1—C1^iii	125.80 (15)
N1^i—Ni1—O2	95.19 (11)	C1—O1—Ni1	85.28 (18)
N1^ii—Ni1—O2	93.29 (11)	C1—O2—Ni1	91.19 (19)
N1^i—Ni1—O2^iii	93.29 (11)	C4—N1—C5	118.2 (3)
N1^ii—Ni1—O2^iii	95.19 (11)	C4—N1—Ni1^iv	123.2 (2)
O2—Ni1—O2^iii	166.71 (14)	C5—N1—Ni1^iv	118.2 (2)
N1^i—Ni1—O1	156.06 (10)	O1—C1—O2	121.4 (3)
N1^ii—Ni1—O1	88.22 (10)	O1—C1—C2	120.0 (3)
O2—Ni1—O1	61.88 (9)	O2—C1—C2	118.6 (3)
O2^iii—Ni1—O1	108.13 (10)	O1—C1—Ni1	63.84 (16)
N1^i—Ni1—O1^iii	88.22 (10)	O2—C1—Ni1	57.75 (16)
N1^ii—Ni1—O1^iii	156.06 (10)	C2—C1—Ni1	174.7 (2)
O2—Ni1—O1^iii	108.13 (10)	C3—C2—C6	119.0 (3)
O2^iii—Ni1—O1^iii	61.88 (9)	C3—C2—C1	121.0 (3)
O1—Ni1—O1^iii	92.51 (12)	C6—C2—C1	119.9 (3)
N1^i—Ni1—C1	126.12 (11)	C2—C3—C4	119.0 (3)
N1^ii—Ni1—C1	89.55 (10)	C2—C3—H3	120.5
O2—Ni1—C1	31.06 (10)	C4—C3—H3	120.5
O2^iii—Ni1—C1	138.70 (10)	N1—C4—C3	122.4 (3)
O1—Ni1—C1	30.88 (10)	N1—C4—H4	118.8
O1^iii—Ni1—C1	103.20 (10)	C3—C4—H4	118.8
N1^i—Ni1—C1^iii	89.55 (10)	N1—C5—C6	122.8 (3)
N1^ii—Ni1—C1^iii	126.12 (11)	N1—C5—H5	118.6
O2—Ni1—C1^iii	138.70 (10)	C6—C5—H5	118.6
O2^iii—Ni1—C1^iii	31.06 (10)	C2—C6—C5	118.5 (3)
O1—Ni1—C1^iii	103.20 (10)	C2—C6—H6	120.7
O1^iii—Ni1—C1^iii	30.88 (10)	C5—C6—H6	120.7

Symmetry codes: (i) −y+1/2, x+1/2, z+3/4; (ii) x+1/2, −y+1/2, −z+1/4; (iii) y, x, −z+1; (iv) x−1/2, −y+1/2, −z+1/4.