A new two-dimensional Cd^II coordination polymer constructed by pyrazine-2,3-dicarboxyl­ate

In the title compound, poly[μ₅-pyrazine-2,3-dicarboxyl­ato-cadmium(II)], [Cd(C₆H₂N₂O₄)]_n or [Cd(pdc)]_n, where pdc is the pyrazine-2,3-dicarboxyl­ate anion, the Cd^II atom is six-coordinated by five carboxyl­ate O atoms and one N atom from five different pdc ligands in a distorted octa­hedral CdO₅N coordination geometry. Two Cd^II atoms are bridged by carboxyl­ate groups of the pdc ligands to create a dimeric unit. The dimeric units are further connected by the pdc ligands to generate an inter­esting two-dimensional structure.

Computing details

Data collection: SMART (Bruker, 1998); cell refinement: SMART (Bruker, 1998); data reduction: SAINT (Bruker, 1998); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1998); software used to prepare material for publication: SHELXTL (Bruker, 1998).

poly[µ₅-pyrazine-2,3-dicarboxylato-cadmium(II)]

Crystal data

[Cd(C6H2N2O4)]	F(000) = 528
Mr = 278.50	Dx = 2.738 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71069 Å
Hall symbol: -P 2ybc	Cell parameters from 1568 reflections
a = 10.728 (6) Å	θ = 1.9–28.4°
b = 7.731 (5) Å	µ = 3.21 mm^−1
c = 8.674 (5) Å	T = 292 K
β = 110.068 (5)°	Block, colourless
V = 675.7 (7) Å^3	0.31 × 0.27 × 0.24 mm
Z = 4

Data collection

Bruker APEX CCD area-detector diffractometer	1568 independent reflections
Radiation source: fine-focus sealed tube	1494 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.039
Detector resolution: none pixels mm^-1	θmax = 28.4°, θmin = 2.0°
φ and ω scans	h = −6→14
Absorption correction: multi-scan (SAINT; Bruker, 1998)	k = −9→9
Tmin = 0.355, Tmax = 0.468	l = −10→11
3843 measured reflections

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)] = 0.023	H-atom parameters constrained
wR(F^2) = 0.054	w = 1/[σ^2(Fo^2) + (0.0256P)^2 + 0.3986P] where P = (Fo^2 + 2Fc^2)/3
S = 1.15	(Δ/σ)max < 0.001
1568 reflections	Δρmax = 0.67 e Å^−3
119 parameters	Δρmin = −0.90 e Å^−3
0 restraints	Extinction correction: SHELXL97 (Sheldrick, 1997), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0257 (11)

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
C1	0.2851 (2)	0.7692 (3)	0.6300 (3)	0.0150 (4)
C2	0.2109 (2)	0.6350 (3)	0.6617 (3)	0.0166 (5)
C3	0.0665 (3)	0.8296 (4)	0.7010 (4)	0.0275 (6)
H3	−0.0079	0.8551	0.7287	0.033*
C4	0.1361 (2)	0.9646 (3)	0.6650 (3)	0.0227 (5)
H4	0.1070	1.0777	0.6669	0.027*
C5	0.2471 (2)	0.4467 (3)	0.6530 (3)	0.0172 (4)
C6	0.4176 (2)	0.7425 (3)	0.6075 (3)	0.0161 (4)
N1	0.24488 (19)	0.9341 (3)	0.6275 (2)	0.0176 (4)
N2	0.1009 (2)	0.6654 (3)	0.6978 (3)	0.0245 (5)
O1	0.43998 (19)	0.8454 (2)	0.5065 (2)	0.0230 (4)
O2	0.2452 (2)	0.3483 (2)	0.7660 (2)	0.0240 (4)
O3	0.2718 (2)	0.4020 (3)	0.5281 (2)	0.0271 (4)
O4	0.49301 (19)	0.6301 (2)	0.6890 (2)	0.0238 (4)
Cd1	0.364000 (16)	1.14258 (2)	0.53924 (2)	0.01699 (10)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0147 (10)	0.0145 (11)	0.0166 (9)	0.0019 (8)	0.0065 (8)	0.0004 (8)
C2	0.0173 (11)	0.0157 (12)	0.0193 (11)	0.0004 (8)	0.0097 (9)	0.0007 (8)
C3	0.0241 (13)	0.0226 (13)	0.0440 (16)	0.0031 (10)	0.0223 (12)	−0.0012 (11)
C4	0.0230 (11)	0.0154 (12)	0.0324 (12)	0.0044 (9)	0.0133 (10)	0.0009 (9)
C5	0.0148 (10)	0.0146 (11)	0.0218 (10)	−0.0010 (8)	0.0058 (8)	0.0007 (8)
C6	0.0153 (10)	0.0161 (11)	0.0190 (10)	−0.0009 (8)	0.0088 (8)	−0.0028 (8)
N1	0.0177 (9)	0.0142 (10)	0.0222 (9)	−0.0003 (8)	0.0086 (7)	0.0007 (7)
N2	0.0213 (11)	0.0187 (11)	0.0408 (13)	0.0004 (8)	0.0199 (10)	0.0021 (9)
O1	0.0226 (9)	0.0224 (10)	0.0306 (10)	0.0015 (6)	0.0176 (8)	0.0068 (7)
O2	0.0277 (10)	0.0188 (10)	0.0237 (9)	−0.0022 (6)	0.0064 (8)	0.0051 (6)
O3	0.0385 (11)	0.0205 (9)	0.0266 (9)	0.0079 (8)	0.0165 (8)	0.0001 (8)
O4	0.0197 (9)	0.0267 (11)	0.0243 (9)	0.0075 (7)	0.0067 (7)	0.0041 (7)
Cd1	0.01718 (13)	0.01466 (14)	0.02154 (13)	0.00040 (5)	0.00972 (8)	0.00082 (5)

Geometric parameters (Å, º)

C1—N1	1.344 (3)	C5—O2	1.246 (3)
C1—C2	1.391 (3)	C5—O3	1.249 (3)
C1—C6	1.514 (3)	C6—O4	1.232 (3)
C2—N2	1.342 (3)	C6—O1	1.266 (3)
C2—C5	1.515 (3)	Cd1—N1	2.342 (2)
C3—N2	1.326 (3)	Cd1—O1	2.486 (2)
C3—C4	1.380 (4)	Cd1—O1^i	2.272 (2)
C3—H3	0.9300	Cd1—O2^ii	2.275 (2)
C4—N1	1.336 (3)	Cd1—O3^iii	2.224 (2)
C4—H4	0.9300	Cd1—O4^iv	2.332 (2)
N1—C1—C2	120.6 (2)	C6—O1—Cd1^i	123.58 (15)
N1—C1—C6	116.0 (2)	C6—O1—Cd1	110.75 (15)
C2—C1—C6	123.3 (2)	Cd1^i—O1—Cd1	109.98 (7)
N2—C2—C1	121.6 (2)	C5—O2—Cd1^v	130.22 (16)
N2—C2—C5	116.1 (2)	C5—O3—Cd1^vi	115.81 (16)
C1—C2—C5	122.2 (2)	C6—O4—Cd1^vii	128.77 (16)
N2—C3—C4	123.0 (2)	O3^iii—Cd1—O1^i	112.34 (7)
N2—C3—H3	118.5	O3^iii—Cd1—O2^ii	81.08 (6)
C4—C3—H3	118.5	O1^i—Cd1—O2^ii	92.19 (8)
N1—C4—C3	120.5 (2)	O3^iii—Cd1—O4^iv	102.10 (7)
N1—C4—H4	119.8	O1^i—Cd1—O4^iv	81.42 (8)
C3—C4—H4	119.8	O2^ii—Cd1—O4^iv	173.55 (7)
O2—C5—O3	125.3 (2)	O3^iii—Cd1—N1	110.51 (8)
O2—C5—C2	118.3 (2)	O1^i—Cd1—N1	136.61 (7)
O3—C5—C2	116.3 (2)	O2^ii—Cd1—N1	100.86 (7)
O4—C6—O1	126.7 (2)	O4^iv—Cd1—N1	83.38 (7)
O4—C6—C1	118.9 (2)	O3^iii—Cd1—O1	170.69 (7)
O1—C6—C1	114.39 (19)	O1^i—Cd1—O1	70.02 (7)
C4—N1—C1	117.8 (2)	O2^ii—Cd1—O1	89.89 (6)
C4—N1—Cd1	125.35 (17)	O4^iv—Cd1—O1	87.11 (7)
C1—N1—Cd1	116.75 (15)	N1—Cd1—O1	68.82 (7)
C3—N2—C2	116.5 (2)
N1—C1—C2—N2	−3.0 (4)	C1—C6—O1—Cd1	40.6 (2)
C6—C1—C2—N2	173.0 (2)	O3—C5—O2—Cd1^v	121.8 (2)
N1—C1—C2—C5	175.3 (2)	C2—C5—O2—Cd1^v	−60.9 (3)
C6—C1—C2—C5	−8.8 (3)	O2—C5—O3—Cd1^vi	−14.8 (3)
N2—C3—C4—N1	−1.2 (5)	C2—C5—O3—Cd1^vi	167.93 (15)
N2—C2—C5—O2	−47.1 (3)	O1—C6—O4—Cd1^vii	97.7 (3)
C1—C2—C5—O2	134.6 (2)	C1—C6—O4—Cd1^vii	−80.1 (3)
N2—C2—C5—O3	130.4 (2)	C4—N1—Cd1—O3^iii	0.5 (2)
C1—C2—C5—O3	−48.0 (3)	C1—N1—Cd1—O3^iii	176.01 (15)
N1—C1—C6—O4	140.9 (2)	C4—N1—Cd1—O1^i	171.02 (18)
C2—C1—C6—O4	−35.2 (3)	C1—N1—Cd1—O1^i	−13.5 (2)
N1—C1—C6—O1	−37.2 (3)	C4—N1—Cd1—O2^ii	−83.9 (2)
C2—C1—C6—O1	146.7 (2)	C1—N1—Cd1—O2^ii	91.56 (16)
C3—C4—N1—C1	−1.6 (4)	C4—N1—Cd1—O4^iv	101.0 (2)
C3—C4—N1—Cd1	173.9 (2)	C1—N1—Cd1—O4^iv	−83.52 (16)
C2—C1—N1—C4	3.6 (3)	C4—N1—Cd1—O1	−169.6 (2)
C6—C1—N1—C4	−172.7 (2)	C1—N1—Cd1—O1	5.94 (14)
C2—C1—N1—Cd1	−172.29 (17)	C6—O1—Cd1—O1^i	140.1 (2)
C6—C1—N1—Cd1	11.4 (2)	Cd1^i—O1—Cd1—O1^i	0.0
C4—C3—N2—C2	1.8 (4)	C6—O1—Cd1—O2^ii	−127.54 (17)
C1—C2—N2—C3	0.3 (4)	Cd1^i—O1—Cd1—O2^ii	92.37 (9)
C5—C2—N2—C3	−178.1 (2)	C6—O1—Cd1—O4^iv	58.17 (17)
O4—C6—O1—Cd1^i	−3.6 (3)	Cd1^i—O1—Cd1—O4^iv	−81.91 (9)
C1—C6—O1—Cd1^i	174.26 (14)	C6—O1—Cd1—N1	−25.84 (15)
O4—C6—O1—Cd1	−137.3 (2)	Cd1^i—O1—Cd1—N1	−165.93 (10)

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