A seven-coordinate pyridine-2,6-di­carboxyl­ate-bridged cadmium(II) complex, at 110 K

The reaction of cadmium(II) chloride monohydrate with a self-assembling pyridine-containing ligand, LH₂ {LH₂ is [H₂pyda]²⁺[pydc]²⁻, where pyda = 2,6-di­amino­pyridine and H₂pydc = pyridine-2,6-di­carboxyl­ic acid}, in water leads to the formation of a centrosymmetric dinuclear Cd^II complex, di-μ-pyridine-2,6-di­carboxyl­ato-bis­[tri­aqua­cadmium(II)], [Cd(pydc)(H₂O)₃]₂·2H₂pydc or [Cd₂(C₇H₃NO₄)₂(H₂O)₆]·2C₇H₅NO₄. Each Cd atom is seven-coordinate and has a distorted pentagonal-bipyramidal geometry. The two metal fragments are linked via the central four-membered Cd₂O₂ ring and there is no [Hpyda]⁺ moiety in the structure of the complex. The structure self-assembles into layers via hydrogen bonds.

Key indicators

• Single-crystal X-ray study
• T = 110 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.039
• wR factor = 0.091
• Data-to-parameter ratio = 17.9

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry


 Alert Level B:



ABSTM_02  Alert B The ratio of expected to reported Tmax/Tmin(RR') is < 0.75
          Tmin and Tmax reported:      0.285     0.862
          Tmin' and Tmax expected:      0.516     0.866
          RR' =      0.555
          Please check that your absorption correction is appropriate.

Author response: ... The values quoted are those present in the outputfile of the SADABS absorption correction program. It is common that they differ appreciably from the SHELXL-97 theoretical values.

 0 Alert Level A = Potentially serious problem

 1 Alert Level B = Potential problem

 0 Alert Level C = Please check

---

Computing details

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

(I)

Crystal data

[Cd2(C7H3O4)2(H2O)6]·2C7H5O4	F(000) = 992
Mr = 997.34	Dx = 2.070 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 9.0531 (16) Å	Cell parameters from 967 reflections
b = 14.667 (3) Å	θ = 3–30°
c = 12.186 (2) Å	µ = 1.44 mm^−1
β = 98.485 (4)°	T = 110 K
V = 1600.4 (5) Å^3	Plate, colorless
Z = 2	0.45 × 0.35 × 0.10 mm

Data collection

Bruker SMART 1000 CCD area-detector diffractometer	4676 independent reflections
Radiation source: fine-focus sealed tube	3769 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.035
φ and ω scans	θmax = 30.1°, θmin = 2.2°
Absorption correction: multi-scan (SADABS; Sheldrick, 1998)	h = −12→12
Tmin = 0.285, Tmax = 0.862	k = −20→20
18834 measured reflections	l = −17→17

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.039	Hydrogen site location: geom and difmap
wR(F^2) = 0.091	H-atom parameters constrained
S = 1.21	w = 1/[σ^2(Fo^2) + (0.045P)^2] where P = (Fo^2 + 2Fc^2)/3
4676 reflections	(Δ/σ)max = 0.002
261 parameters	Δρmax = 2.85 e Å^−3
0 restraints	Δρmin = −0.96 e Å^−3

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
Cd1	0.08391 (2)	0.915353 (13)	0.902269 (16)	0.01153 (7)
O1	−0.0780 (2)	0.93091 (13)	1.03935 (16)	0.0130 (4)
O2	−0.2026 (2)	0.85577 (13)	1.15671 (17)	0.0150 (4)
O3	0.1482 (2)	0.79271 (13)	0.78084 (17)	0.0152 (4)
O4	0.1391 (2)	0.64399 (13)	0.74347 (17)	0.0155 (4)
O1W	−0.0994 (2)	0.96293 (13)	0.76298 (17)	0.0154 (4)
H1WA	−0.1138	1.0188	0.7608	0.015 (8)*
H1WB	−0.1875	0.9454	0.7751	0.050 (14)*
O2W	0.2613 (2)	0.97219 (13)	0.80776 (17)	0.0165 (4)
H2WA	0.2559	0.9581	0.7397	0.017 (9)*
H2WB	0.2541	1.0284	0.8084	0.058 (15)*
O3W	0.2884 (2)	0.90593 (13)	1.05349 (17)	0.0145 (4)
H3WA	0.2649	0.8872	1.1147	0.039 (12)*
H3WB	0.3379	0.8647	1.0459	0.056 (16)*
N1	−0.0158 (2)	0.77532 (15)	0.94144 (19)	0.0114 (4)
C2	−0.0986 (3)	0.77090 (17)	1.0233 (2)	0.0101 (5)
C3	−0.1561 (3)	0.68894 (18)	1.0563 (2)	0.0144 (5)
H3A	−0.2128	0.6870	1.1159	0.017*
C4	−0.1282 (3)	0.61024 (19)	0.9995 (2)	0.0160 (5)
H4A	−0.1668	0.5532	1.0191	0.019*
C5	−0.0433 (3)	0.61583 (19)	0.9139 (2)	0.0149 (5)
H5A	−0.0237	0.5628	0.8736	0.018*
C6	0.0123 (3)	0.69967 (18)	0.8879 (2)	0.0115 (5)
C7	−0.1291 (3)	0.85964 (18)	1.0789 (2)	0.0118 (5)
C8	0.1070 (3)	0.71155 (18)	0.7960 (2)	0.0121 (5)
O5	0.3025 (2)	0.77816 (13)	0.62702 (18)	0.0191 (4)
H5O	0.2555	0.7898	0.6840	0.034 (11)*
O6	0.2991 (3)	0.92695 (14)	0.59154 (18)	0.0203 (5)
O7	0.5754 (2)	0.57418 (14)	0.44913 (18)	0.0169 (4)
H7O	0.6119	0.5259	0.4429	0.047 (14)*
O8	0.6201 (2)	0.60253 (15)	0.27671 (18)	0.0212 (5)
N2	0.4551 (2)	0.74047 (16)	0.46387 (19)	0.0128 (4)
C9	0.4165 (3)	0.82764 (18)	0.4773 (2)	0.0130 (5)
C10	0.4463 (3)	0.89774 (19)	0.4070 (2)	0.0153 (5)
H10A	0.4174	0.9586	0.4201	0.018*
C11	0.5184 (3)	0.8776 (2)	0.3181 (2)	0.0170 (6)
H11A	0.5390	0.9241	0.2682	0.020*
C12	0.5602 (3)	0.7880 (2)	0.3030 (2)	0.0164 (5)
H12A	0.6102	0.7718	0.2426	0.020*
C13	0.5272 (3)	0.72249 (18)	0.3783 (2)	0.0130 (5)
C14	0.3335 (3)	0.84903 (19)	0.5718 (2)	0.0144 (5)
C15	0.5774 (3)	0.6264 (2)	0.3624 (2)	0.0154 (5)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cd1	0.01394 (11)	0.00909 (10)	0.01269 (11)	−0.00075 (7)	0.00569 (7)	−0.00055 (7)
O1	0.0162 (9)	0.0109 (9)	0.0133 (9)	−0.0008 (7)	0.0066 (7)	−0.0010 (7)
O2	0.0188 (10)	0.0120 (9)	0.0162 (10)	−0.0017 (7)	0.0091 (8)	−0.0004 (7)
O3	0.0201 (10)	0.0114 (9)	0.0161 (10)	−0.0019 (7)	0.0092 (8)	−0.0013 (7)
O4	0.0180 (10)	0.0120 (9)	0.0177 (10)	0.0005 (7)	0.0072 (8)	−0.0041 (7)
O1W	0.0169 (10)	0.0110 (9)	0.0191 (10)	−0.0002 (7)	0.0047 (8)	0.0010 (7)
O2W	0.0224 (10)	0.0120 (9)	0.0176 (10)	−0.0018 (8)	0.0110 (8)	−0.0024 (7)
O3W	0.0150 (9)	0.0149 (10)	0.0143 (10)	0.0016 (8)	0.0050 (8)	0.0014 (7)
N1	0.0117 (10)	0.0107 (10)	0.0119 (10)	−0.0009 (8)	0.0027 (8)	−0.0009 (8)
C2	0.0118 (11)	0.0102 (11)	0.0085 (11)	0.0005 (9)	0.0019 (9)	0.0008 (9)
C3	0.0167 (13)	0.0121 (12)	0.0153 (13)	−0.0035 (10)	0.0049 (10)	−0.0012 (10)
C4	0.0205 (14)	0.0102 (12)	0.0182 (14)	−0.0033 (10)	0.0062 (11)	0.0005 (10)
C5	0.0192 (13)	0.0097 (12)	0.0162 (13)	−0.0008 (10)	0.0043 (10)	−0.0004 (10)
C6	0.0105 (11)	0.0115 (12)	0.0125 (12)	0.0012 (9)	0.0015 (9)	−0.0016 (9)
C7	0.0122 (12)	0.0127 (12)	0.0108 (12)	−0.0007 (9)	0.0024 (9)	0.0006 (9)
C8	0.0108 (11)	0.0115 (12)	0.0141 (12)	0.0005 (9)	0.0018 (9)	−0.0001 (9)
O5	0.0281 (11)	0.0129 (9)	0.0202 (10)	−0.0004 (8)	0.0160 (9)	−0.0004 (8)
O6	0.0293 (12)	0.0148 (10)	0.0189 (11)	0.0041 (8)	0.0103 (9)	0.0007 (8)
O7	0.0187 (10)	0.0149 (10)	0.0183 (10)	0.0037 (8)	0.0067 (8)	−0.0004 (8)
O8	0.0219 (11)	0.0246 (11)	0.0188 (11)	0.0045 (9)	0.0086 (9)	−0.0035 (9)
N2	0.0129 (10)	0.0131 (11)	0.0134 (11)	0.0003 (9)	0.0048 (8)	−0.0009 (8)
C9	0.0126 (12)	0.0129 (12)	0.0136 (12)	−0.0003 (9)	0.0024 (10)	−0.0008 (9)
C10	0.0160 (13)	0.0143 (13)	0.0163 (13)	−0.0014 (10)	0.0042 (10)	0.0010 (10)
C11	0.0191 (14)	0.0156 (13)	0.0176 (14)	−0.0050 (11)	0.0064 (11)	0.0019 (11)
C12	0.0150 (13)	0.0206 (14)	0.0151 (13)	−0.0034 (11)	0.0069 (10)	−0.0006 (11)
C13	0.0098 (11)	0.0147 (12)	0.0149 (12)	−0.0004 (9)	0.0036 (10)	−0.0026 (10)
C14	0.0145 (12)	0.0139 (13)	0.0146 (13)	0.0002 (10)	0.0013 (10)	−0.0005 (10)
C15	0.0106 (12)	0.0180 (14)	0.0182 (13)	−0.0009 (10)	0.0041 (10)	−0.0029 (11)

Geometric parameters (Å, º)

Cd1—O2W	2.269 (2)	C3—H3A	0.9500
Cd1—O1W	2.300 (2)	C4—C5	1.387 (4)
Cd1—N1	2.321 (2)	C4—H4A	0.9500
Cd1—O1^i	2.3674 (19)	C5—C6	1.383 (4)
Cd1—O1	2.3902 (19)	C5—H5A	0.9500
Cd1—O3W	2.416 (2)	C6—C8	1.518 (4)
Cd1—O3	2.4532 (19)	O5—C14	1.291 (3)
O1—C7	1.267 (3)	O5—H5O	0.8834
O1—Cd1^i	2.3674 (19)	O6—C14	1.218 (3)
O2—C7	1.237 (3)	O7—C15	1.308 (4)
O3—C8	1.269 (3)	O7—H7O	0.7898
O4—C8	1.237 (3)	O8—C15	1.217 (4)
O1W—H1WA	0.8299	N2—C13	1.336 (3)
O1W—H1WB	0.8715	N2—C9	1.342 (3)
O2W—H2WA	0.8490	C9—C10	1.390 (4)
O2W—H2WB	0.8270	C9—C14	1.498 (4)
O3W—H3WA	0.8506	C10—C11	1.377 (4)
O3W—H3WB	0.7669	C10—H10A	0.9500
N1—C6	1.330 (3)	C11—C12	1.387 (4)
N1—C2	1.335 (3)	C11—H11A	0.9500
C2—C3	1.393 (4)	C12—C13	1.391 (4)
C2—C7	1.512 (4)	C12—H12A	0.9500
C3—C4	1.388 (4)	C13—C15	1.502 (4)
O2W—Cd1—O1W	90.09 (7)	C4—C3—H3A	121.0
O2W—Cd1—N1	139.06 (7)	C2—C3—H3A	121.0
O1W—Cd1—N1	99.22 (8)	C5—C4—C3	119.2 (3)
O2W—Cd1—O1^i	81.47 (7)	C5—C4—H4A	120.4
O1W—Cd1—O1^i	83.51 (7)	C3—C4—H4A	120.4
N1—Cd1—O1^i	138.96 (7)	C6—C5—C4	119.0 (3)
O2W—Cd1—O1	150.78 (7)	C6—C5—H5A	120.5
O1W—Cd1—O1	92.11 (7)	C4—C5—H5A	120.5
N1—Cd1—O1	69.12 (7)	N1—C6—C5	121.8 (2)
O1^i—Cd1—O1	69.85 (7)	N1—C6—C8	115.8 (2)
O2W—Cd1—O3W	83.58 (7)	C5—C6—C8	122.4 (2)
O1W—Cd1—O3W	165.59 (7)	O2—C7—O1	126.7 (3)
N1—Cd1—O3W	94.01 (7)	O2—C7—C2	117.3 (2)
O1^i—Cd1—O3W	82.77 (7)	O1—C7—C2	116.0 (2)
O1—Cd1—O3W	87.26 (7)	O4—C8—O3	125.4 (3)
O2W—Cd1—O3	73.41 (7)	O4—C8—C6	119.4 (2)
O1W—Cd1—O3	89.24 (7)	O3—C8—C6	115.2 (2)
N1—Cd1—O3	67.00 (7)	C14—O5—H5O	114.9
O1^i—Cd1—O3	153.84 (7)	C15—O7—H7O	113.1
O1—Cd1—O3	135.73 (6)	C13—N2—C9	116.7 (2)
O3W—Cd1—O3	101.24 (7)	N2—C9—C10	123.5 (3)
C7—O1—Cd1^i	130.21 (17)	N2—C9—C14	117.6 (2)
C7—O1—Cd1	118.91 (17)	C10—C9—C14	118.9 (2)
Cd1^i—O1—Cd1	110.15 (7)	C11—C10—C9	119.0 (3)
C8—O3—Cd1	119.93 (16)	C11—C10—H10A	120.5
Cd1—O1W—H1WA	114.6	C9—C10—H10A	120.5
Cd1—O1W—H1WB	111.4	C10—C11—C12	118.6 (3)
H1WA—O1W—H1WB	98.8	C10—C11—H11A	120.7
Cd1—O2W—H2WA	117.6	C12—C11—H11A	120.7
Cd1—O2W—H2WB	107.4	C11—C12—C13	118.5 (3)
H2WA—O2W—H2WB	105.0	C11—C12—H12A	120.7
Cd1—O3W—H3WA	115.2	C13—C12—H12A	120.7
Cd1—O3W—H3WB	110.4	N2—C13—C12	123.8 (3)
H3WA—O3W—H3WB	94.4	N2—C13—C15	118.6 (2)
C6—N1—C2	119.6 (2)	C12—C13—C15	117.7 (2)
C6—N1—Cd1	121.94 (18)	O6—C14—O5	124.8 (3)
C2—N1—Cd1	118.35 (17)	O6—C14—C9	121.4 (3)
N1—C2—C3	122.2 (2)	O5—C14—C9	113.8 (2)
N1—C2—C7	117.0 (2)	O8—C15—O7	124.7 (3)
C3—C2—C7	120.8 (2)	O8—C15—C13	121.4 (3)
C4—C3—C2	118.1 (2)	O7—C15—C13	113.9 (2)
O2W—Cd1—O1—C7	−159.51 (19)	C2—N1—C6—C5	0.6 (4)
O1W—Cd1—O1—C7	106.5 (2)	Cd1—N1—C6—C5	177.9 (2)
N1—Cd1—O1—C7	7.47 (19)	C2—N1—C6—C8	179.8 (2)
O1^i—Cd1—O1—C7	−171.2 (2)	Cd1—N1—C6—C8	−2.9 (3)
O3W—Cd1—O1—C7	−87.9 (2)	C4—C5—C6—N1	−1.3 (4)
O3—Cd1—O1—C7	15.4 (2)	C4—C5—C6—C8	179.6 (3)
O2W—Cd1—O1—Cd1^i	11.67 (19)	Cd1^i—O1—C7—O2	3.9 (4)
O1W—Cd1—O1—Cd1^i	−82.29 (9)	Cd1—O1—C7—O2	173.1 (2)
N1—Cd1—O1—Cd1^i	178.65 (11)	Cd1^i—O1—C7—C2	−177.18 (16)
O1^i—Cd1—O1—Cd1^i	0.0	Cd1—O1—C7—C2	−8.1 (3)
O3W—Cd1—O1—Cd1^i	83.30 (8)	N1—C2—C7—O2	−178.2 (2)
O3—Cd1—O1—Cd1^i	−173.38 (7)	C3—C2—C7—O2	2.3 (4)
O2W—Cd1—O3—C8	166.1 (2)	N1—C2—C7—O1	2.8 (4)
O1W—Cd1—O3—C8	−103.6 (2)	C3—C2—C7—O1	−176.7 (3)
N1—Cd1—O3—C8	−3.22 (19)	Cd1—O3—C8—O4	−176.4 (2)
O1^i—Cd1—O3—C8	−177.10 (18)	Cd1—O3—C8—C6	2.9 (3)
O1—Cd1—O3—C8	−11.3 (2)	N1—C6—C8—O4	179.2 (2)
O3W—Cd1—O3—C8	86.4 (2)	C5—C6—C8—O4	−1.6 (4)
O2W—Cd1—N1—C6	−12.6 (3)	N1—C6—C8—O3	−0.2 (4)
O1W—Cd1—N1—C6	88.3 (2)	C5—C6—C8—O3	179.0 (3)
O1^i—Cd1—N1—C6	179.01 (18)	C13—N2—C9—C10	0.7 (4)
O1—Cd1—N1—C6	177.1 (2)	C13—N2—C9—C14	179.1 (2)
O3W—Cd1—N1—C6	−97.4 (2)	N2—C9—C10—C11	0.4 (4)
O3—Cd1—N1—C6	3.1 (2)	C14—C9—C10—C11	−177.9 (3)
O2W—Cd1—N1—C2	164.70 (17)	C9—C10—C11—C12	−0.8 (4)
O1W—Cd1—N1—C2	−94.4 (2)	C10—C11—C12—C13	0.1 (4)
O1^i—Cd1—N1—C2	−3.7 (3)	C9—N2—C13—C12	−1.5 (4)
O1—Cd1—N1—C2	−5.64 (19)	C9—N2—C13—C15	177.8 (2)
O3W—Cd1—N1—C2	79.9 (2)	C11—C12—C13—N2	1.1 (4)
O3—Cd1—N1—C2	−179.6 (2)	C11—C12—C13—C15	−178.2 (3)
C6—N1—C2—C3	0.8 (4)	N2—C9—C14—O6	177.5 (3)
Cd1—N1—C2—C3	−176.5 (2)	C10—C9—C14—O6	−4.1 (4)
C6—N1—C2—C7	−178.7 (2)	N2—C9—C14—O5	−3.1 (4)
Cd1—N1—C2—C7	4.0 (3)	C10—C9—C14—O5	175.3 (3)
N1—C2—C3—C4	−1.5 (4)	N2—C13—C15—O8	167.2 (3)
C7—C2—C3—C4	177.9 (3)	C12—C13—C15—O8	−13.4 (4)
C2—C3—C4—C5	0.8 (4)	N2—C13—C15—O7	−15.0 (4)
C3—C4—C5—C6	0.5 (4)	C12—C13—C15—O7	164.3 (3)

Symmetry code: (i) −x, −y+2, −z+2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O1W—H1WA···O4^ii	0.83	1.85	2.679 (3)	178
O1W—H1WB···O8^iii	0.87	1.88	2.743 (3)	170
O2W—H2WA···O6	0.85	1.96	2.787 (3)	165
O2W—H2WB···O2^i	0.83	1.83	2.628 (3)	162
O3W—H3WA···O4^iv	0.85	2.12	2.940 (3)	162
O3W—H3WB···N2^iv	0.77	2.19	2.927 (3)	160
O5—H5O···O3	0.88	1.64	2.507 (3)	168
O7—H7O···O3W^v	0.79	1.97	2.761 (3)	173

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