Tetra­aqua-trans-bis­(nicotinato-κN)­cadmium(II)

The title compound, [Cd(C₆H₄NO₂)₂(H₂O)₄], was synthesized by the hydro­thermal reaction of cadmium chloride and nicotinic acid. Crystallographic analysis reveals it to be a new nicotinic acid complex. The molecule has crystallographic 2/m symmetry. The hydrogen-bonding interaction between the mol­ecules results in a three-dimensional supramolecular structure.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.010 Å
• R factor = 0.038
• wR factor = 0.095
• Data-to-parameter ratio = 8.2

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level C:



ABSTM_02  Alert C The ratio of expected to reported Tmax/Tmin(RR') is < 0.90
          Tmin and Tmax reported:      0.520     0.839
          Tmin' and Tmax expected:      0.587     0.839
          RR' =      0.886
          Please check that your absorption correction is appropriate.


 0 Alert Level A = Potentially serious problem

 0 Alert Level B = Potential problem

 1 Alert Level C = Please check

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S1. Comment

Recently, the design and syntheses of non-centrosymmetric transition metal complexes attracted widespread attention for it is an essential requirement for a bulk material to exhibit non-linear optical (NLO) effects. We have investigated the coordination chemistry of nicotinic acid complexes. Our interest in these systems stems from the lack of a center of symmetry in the ligand. In addition, the introduction of electronic asymmetry (push–pull effects) through the bifunctional m-pyridinecarboxylate group is necessary for the second-order optical non-linearity. The reason that we adopted the Cd atom as the metal center is because its complexes are usually colorless, which is good for optical materials. Several nicotinic acid–transition metal complexes have been synthesized and studied, such as zinc (Lin et al., 1998; Cotton et al., 1991), chromium(II) (Cotton et al., 1991; Broderick et al., 1986). cobalt and copper (Waizumi et al., 1998), and nickel (Batten et al., 2001)

Here we report a new cadmium(II) complex, tetraaqua-trans-bis(nicotinato-κN)cadmium(II), (I). X-Ray single-crystal diffraction analysis reveals that it is isomorphous with other transition metal dinicotinates and crystallizes in the C2/m space group. Each cadmium(II) center is coordinated by two N atoms from two nicotinate groups and four O atoms from four coordinated water molecules in a slightly distorted octahedral geometry. Two nicotinate groups are in trans positions. The Cd—N and Cd—O bond lengths are 2.309 (5) and 2.321 (4) Å, respectively (Table 1).

The O atom of each coordinated water molecule forms bifurcated hydrogen bonds with the carbonyl O atom of nicotinate groups (Table 2). The intermolecular hydrogen-bonding interactions thus link the molecules into hydrogen-bonded three-dimensional crystal structure, as shown in Fig. 2.

S2. Experimental

The hydrothermal reaction of cadmium chloride (0.05 g, 0.27 mmol) and nicotinic acid (0.04 g, 0.32 mmol) in the molar ratio of 1:1 at 443 K for 5 d. After cooling to room temperature at 5 K h⁻¹, colorless platelet crystals of (I) were isolated in 63% yield (base on Cd). Elemental analysis calculated for C₁₂H₁₆CdN₂O₈: C 33.62, H 3.76, N 6.53%; found: C 33.41, H 3.43, N 6.51%.

S3. Refinement

All H atoms were located in a difference Fourier map and refined freely [C—H = 0.79 (11)–1.00 (9) Å], along with an isotropic displacement parameter.

Computing details

Data collection: SMART (Siemens, 1996); cell refinement: SMART; data reduction: XPREP (Bruker, 1997); program(s) used to solve structure: SHELXTL (Siemens, 1994); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXL97 (Sheldrick, 1997); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. View of the molecule of the title complex, showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level and H atoms are represented by circles of arbitrary size.
	Fig. 2. The molecular packing of the title complex. H atoms bonded to C atoms have been omitted for clarity.

Tetraaqua-trans-bis(nicotinato-κN)cadmium(II)

Crystal data

[Cd(C6H4NO2)2(H2O)4]	F(000) = 428
Mr = 428.68	Dx = 1.850 Mg m^−3
Monoclinic, C2/m	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2y	Cell parameters from 35 reflections
a = 14.5727 (8) Å	θ = 2.7–25.0°
b = 6.9988 (1) Å	µ = 1.46 mm^−1
c = 8.5447 (5) Å	T = 293 K
β = 118.012 (3)°	Plate, colorless
V = 769.39 (7) Å^3	0.36 × 0.14 × 0.12 mm
Z = 2

Data collection

Siemens SMART CCD diffractometer	733 independent reflections
Radiation source: fine-focus sealed tube	718 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.037
ω scans	θmax = 25.0°, θmin = 2.7°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −15→17
Tmin = 0.520, Tmax = 0.839	k = −8→8
1341 measured reflections	l = −9→10

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.038	All H-atom parameters refined
wR(F^2) = 0.095	w = 1/[σ^2(Fo^2) + (0.0528P)^2 + 0.4415P] where P = (Fo^2 + 2Fc^2)/3
S = 1.15	(Δ/σ)max < 0.001
733 reflections	Δρmax = 1.03 e Å^−3
89 parameters	Δρmin = −0.83 e Å^−3
0 restraints	Extinction correction: SHELXL97, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.019 (2)

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.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

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

	x	y	z	Uiso*/Ueq
Cd	0.0000	0.0000	0.0000	0.0304 (4)
C1	0.2387 (6)	0.0000	0.7435 (9)	0.0380 (16)
C2	0.2466 (5)	0.0000	0.5754 (8)	0.0288 (14)
C3	0.3408 (5)	0.0000	0.5726 (9)	0.0376 (16)
H3	0.398 (7)	0.0000	0.668 (12)	0.06 (3)*
C4	0.3411 (5)	0.0000	0.4122 (10)	0.0397 (17)
H4	0.390 (8)	0.0000	0.394 (13)	0.07 (3)*
C5	0.2483 (5)	0.0000	0.2583 (9)	0.0339 (15)
H5	0.252 (8)	0.0000	0.157 (13)	0.07 (3)*
C6	0.1566 (5)	0.0000	0.4141 (8)	0.0295 (14)
H6	0.087 (7)	0.0000	0.411 (11)	0.06 (3)*
N	0.1564 (4)	0.0000	0.2577 (7)	0.0303 (12)
O1	0.0606 (3)	0.2301 (6)	−0.1246 (5)	0.0403 (9)
H1A	0.098 (5)	0.184 (11)	−0.167 (8)	0.06 (2)*
H1B	0.098 (6)	0.309 (12)	−0.058 (9)	0.07 (2)*
O2	0.1490 (5)	0.0000	0.7295 (8)	0.0551 (15)
O3	0.3220 (5)	0.0000	0.8877 (6)	0.0525 (14)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cd	0.0242 (4)	0.0361 (5)	0.0266 (4)	0.000	0.0083 (3)	0.000
C1	0.060 (5)	0.023 (4)	0.034 (4)	0.000	0.025 (3)	0.000
C2	0.032 (3)	0.019 (3)	0.030 (3)	0.000	0.010 (3)	0.000
C3	0.027 (3)	0.039 (4)	0.037 (4)	0.000	0.007 (3)	0.000
C4	0.023 (3)	0.054 (5)	0.041 (4)	0.000	0.014 (3)	0.000
C5	0.032 (3)	0.035 (4)	0.037 (4)	0.000	0.018 (3)	0.000
C6	0.030 (3)	0.031 (4)	0.027 (3)	0.000	0.013 (3)	0.000
N	0.028 (3)	0.029 (3)	0.032 (3)	0.000	0.013 (2)	0.000
O1	0.0399 (19)	0.036 (2)	0.044 (2)	−0.0063 (17)	0.0188 (18)	0.0011 (17)
O2	0.066 (4)	0.064 (4)	0.052 (3)	0.000	0.041 (3)	0.000
O3	0.073 (4)	0.039 (3)	0.027 (3)	0.000	0.008 (3)	0.000

Geometric parameters (Å, º)

Cd—N	2.309 (5)	C3—C4	1.373 (10)
Cd—N^i	2.309 (5)	C3—H3	0.85 (9)
Cd—O1^ii	2.321 (4)	C4—C5	1.374 (10)
Cd—O1^iii	2.321 (4)	C4—H4	0.79 (11)
Cd—O1^i	2.321 (4)	C5—N	1.336 (8)
Cd—O1	2.321 (4)	C5—H5	0.89 (10)
C1—O2	1.254 (10)	C6—N	1.335 (8)
C1—O3	1.260 (9)	C6—H6	1.00 (9)
C1—C2	1.495 (9)	O1—H1A	0.84 (7)
C2—C3	1.383 (9)	O1—H1B	0.80 (8)
C2—C6	1.386 (9)
N—Cd—N^i	180.0 (4)	C6—C2—C1	119.5 (6)
N—Cd—O1^ii	91.13 (13)	C4—C3—C2	119.0 (6)
N^i—Cd—O1^ii	88.87 (13)	C4—C3—H3	120 (6)
N—Cd—O1^iii	88.87 (13)	C2—C3—H3	121 (7)
N^i—Cd—O1^iii	91.13 (13)	C3—C4—C5	119.5 (6)
O1^ii—Cd—O1^iii	180.00 (17)	C3—C4—H4	128 (7)
N—Cd—O1^i	88.87 (13)	C5—C4—H4	113 (7)
N^i—Cd—O1^i	91.13 (13)	N—C5—C4	122.5 (6)
O1^ii—Cd—O1^i	92.1 (2)	N—C5—H5	121 (6)
O1^iii—Cd—O1^i	87.9 (2)	C4—C5—H5	117 (6)
N—Cd—O1	91.13 (13)	N—C6—C2	123.5 (6)
N^i—Cd—O1	88.87 (13)	N—C6—H6	117 (5)
O1^ii—Cd—O1	87.9 (2)	C2—C6—H6	120 (5)
O1^iii—Cd—O1	92.1 (2)	C6—N—C5	117.7 (6)
O1^i—Cd—O1	180.0 (2)	C6—N—Cd	119.5 (4)
O2—C1—O3	125.2 (7)	C5—N—Cd	122.8 (4)
O2—C1—C2	117.1 (6)	Cd—O1—H1A	113 (5)
O3—C1—C2	117.8 (7)	Cd—O1—H1B	116 (5)
C3—C2—C6	117.8 (6)	H1A—O1—H1B	102 (6)
C3—C2—C1	122.8 (6)
O2—C1—C2—C3	180.000 (3)	C2—C6—N—Cd	180.000 (1)
O3—C1—C2—C3	0.000 (3)	C4—C5—N—C6	0.0
O2—C1—C2—C6	0.000 (3)	C4—C5—N—Cd	180.000 (1)
O3—C1—C2—C6	180.000 (3)	O1^ii—Cd—N—C6	−136.06 (11)
C6—C2—C3—C4	0.000 (2)	O1^iii—Cd—N—C6	43.94 (11)
C1—C2—C3—C4	180.000 (2)	O1^i—Cd—N—C6	−43.94 (11)
C2—C3—C4—C5	0.000 (2)	O1—Cd—N—C6	136.06 (11)
C3—C4—C5—N	0.000 (1)	O1^ii—Cd—N—C5	43.94 (11)
C3—C2—C6—N	0.000 (2)	O1^iii—Cd—N—C5	−136.06 (11)
C1—C2—C6—N	180.000 (2)	O1^i—Cd—N—C5	136.06 (11)
C2—C6—N—C5	0.000 (1)	O1—Cd—N—C5	−43.94 (11)

Symmetry codes: (i) −x, −y, −z; (ii) x, −y, z; (iii) −x, y, −z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1—H1A···O2^iv	0.84 (7)	1.90 (8)	2.705 (7)	158 (?)
O1—H1B···O3^v	0.80 (8)	1.92 (8)	2.709 (5)	173 (?)

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