Di­aqua­bis­(pyridine-2-carbox­amide-κ²N¹,O²)copper(II) squarate

The title compound, [Cu(C₆H₆N₂O)₂(H₂O)₂](C₄O₄) [or Cu(pia)₂(H₂O)₂.Sq, where pia is picolin­amide or pyridine-2-carboxy­amide, and Sq is the squarate dianion, (C₄O₄)²⁻], has been synthesized and the crystal structure determination is reported. The Cu²⁺ cation, located on a centre of symmetry, is coordinated by two symmetry-related aqua ligands together with a pair of symmetry-related bidentate pia mol­ecules and exhibits elongated octahedral trans-[CuN₂O₄] coordination geometry. The unligated Sq dianion also lies on a crystallographic inversion centre. The squarate O atoms link the Sq ions to the metal complex via O—H...O and O—H...N hydrogen bonds. Intermolecular π–π and C—H...π interactions between the moieties also stabilize the crystal structure.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.002 Å
• R factor = 0.025
• wR factor = 0.072
• Data-to-parameter ratio = 15.8

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT232_ALERT_2_C Hirshfeld Test Diff (M-X)  Cu1    -   O1      ..       7.15 su
PLAT232_ALERT_2_C Hirshfeld Test Diff (M-X)  Cu1    -   O2      ..       9.07 su
PLAT232_ALERT_2_C Hirshfeld Test Diff (M-X)  Cu1    -   N2      ..       6.68 su
PLAT480_ALERT_4_C Long H...A H-Bond Reported H6     ..  CG1     ..       3.13 Ang.

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   4 ALERT level C = Check and explain
   0 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   3 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion

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Computing details

Data collection: X-AREA (Stoe & Cie, 2002); cell refinement: X-AREA; data reduction: X-RED32 (Stoe & Cie, 2002); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Burnett & Johnson, 1996); software used to prepare material for publication: WinGX (Farrugia, 1999).

Diaquabis(pyridine-2-carboxamide-κ²N¹,O²)copper(II) squarate

Crystal data

[Cu(C6H6N2O)2(H2O)2](C4O4)	Z = 1
Mr = 455.87	F(000) = 233
Triclinic, P1	Dx = 1.784 Mg m^−3
Hall symbol: -P 1	Mo Kα radiation, λ = 0.71073 Å
a = 7.1240 (9) Å	Cell parameters from 13950 reflections
b = 7.7627 (9) Å	θ = 2.7–29.7°
c = 8.1191 (9) Å	µ = 1.35 mm^−1
α = 108.150 (9)°	T = 293 K
β = 92.225 (10)°	Prism, green
γ = 94.531 (10)°	0.42 × 0.27 × 0.18 mm
V = 424.37 (9) Å^3

Data collection

Stoe IPDS-2 diffractometer	2361 independent reflections
Radiation source: fine-focus sealed tube	2241 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.070
Detector resolution: 6.67 pixels mm^-1	θmax = 29.6°, θmin = 2.7°
ω scans	h = −9→9
Absorption correction: integration (X-RED32; Stoe & Cie, 2002)	k = −10→10
Tmin = 0.656, Tmax = 0.803	l = −11→11
8483 measured reflections

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)] = 0.025	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.072	H atoms treated by a mixture of independent and constrained refinement
S = 1.10	w = 1/[σ^2(Fo^2) + (0.0346P)^2 + 0.1621P] where P = (Fo^2 + 2Fc^2)/3
2361 reflections	(Δ/σ)max < 0.001
149 parameters	Δρmax = 0.40 e Å^−3
4 restraints	Δρmin = −0.34 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
C1	0.21475 (19)	0.32463 (17)	1.14790 (17)	0.0270 (2)
C2	0.16763 (18)	0.32436 (16)	0.96700 (17)	0.0244 (2)
C3	0.2272 (2)	0.45950 (18)	0.89902 (19)	0.0313 (3)
H3	0.3045	0.5614	0.9660	0.038*
C4	0.1698 (2)	0.4407 (2)	0.7288 (2)	0.0369 (3)
H4	0.2088	0.5298	0.6796	0.044*
C5	0.0547 (3)	0.2889 (2)	0.6333 (2)	0.0379 (3)
H5	0.0144	0.2740	0.5189	0.045*
C6	−0.0003 (2)	0.1586 (2)	0.71037 (19)	0.0330 (3)
H6	−0.0788	0.0562	0.6463	0.040*
C7	0.47741 (19)	−0.08788 (17)	0.37386 (17)	0.0262 (2)
C8	0.5383 (2)	0.10690 (17)	0.45315 (17)	0.0276 (3)
N1	0.3271 (2)	0.45972 (18)	1.25195 (18)	0.0374 (3)
N2	0.05588 (17)	0.17558 (15)	0.87345 (15)	0.0264 (2)
O1	0.14535 (16)	0.19543 (14)	1.19395 (13)	0.0343 (2)
O2	0.29209 (19)	−0.11154 (19)	0.93404 (17)	0.0439 (3)
O3	0.44753 (17)	−0.19531 (14)	0.22224 (13)	0.0354 (2)
O4	0.58527 (19)	0.23626 (15)	0.39787 (15)	0.0420 (3)
Cu1	0.0000	0.0000	1.0000	0.02944 (9)
H1A	0.366 (3)	0.556 (2)	1.228 (3)	0.046 (6)*
H1B	0.356 (4)	0.454 (4)	1.353 (2)	0.064 (7)*
H2A	0.345 (4)	−0.132 (4)	0.845 (3)	0.059 (7)*
H2B	0.359 (3)	−0.118 (3)	1.016 (2)	0.045 (6)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
C1	0.0309 (6)	0.0227 (5)	0.0258 (6)	−0.0030 (5)	0.0004 (5)	0.0068 (5)
C2	0.0275 (6)	0.0196 (5)	0.0258 (6)	−0.0009 (4)	0.0030 (4)	0.0074 (4)
C3	0.0371 (7)	0.0229 (6)	0.0343 (7)	−0.0047 (5)	0.0028 (5)	0.0113 (5)
C4	0.0496 (8)	0.0296 (7)	0.0359 (7)	−0.0019 (6)	0.0052 (6)	0.0179 (6)
C5	0.0525 (9)	0.0352 (7)	0.0282 (7)	−0.0004 (6)	0.0007 (6)	0.0146 (6)
C6	0.0423 (7)	0.0285 (6)	0.0257 (6)	−0.0052 (5)	−0.0014 (5)	0.0077 (5)
C7	0.0318 (6)	0.0226 (5)	0.0235 (6)	−0.0032 (4)	−0.0015 (5)	0.0080 (5)
C8	0.0353 (6)	0.0235 (6)	0.0235 (6)	−0.0046 (5)	−0.0020 (5)	0.0091 (5)
N1	0.0467 (7)	0.0308 (6)	0.0312 (6)	−0.0141 (5)	−0.0086 (5)	0.0104 (5)
N2	0.0328 (5)	0.0213 (5)	0.0243 (5)	−0.0042 (4)	0.0018 (4)	0.0078 (4)
O1	0.0465 (6)	0.0289 (5)	0.0263 (5)	−0.0127 (4)	−0.0031 (4)	0.0113 (4)
O2	0.0471 (7)	0.0563 (7)	0.0341 (6)	0.0098 (6)	0.0054 (5)	0.0211 (6)
O3	0.0519 (6)	0.0274 (5)	0.0225 (5)	−0.0062 (4)	−0.0023 (4)	0.0046 (4)
O4	0.0668 (8)	0.0289 (5)	0.0309 (5)	−0.0125 (5)	−0.0020 (5)	0.0151 (4)
Cu1	0.04224 (15)	0.02166 (12)	0.02307 (12)	−0.01158 (9)	−0.00145 (9)	0.00909 (8)

Geometric parameters (Å, º)

C1—O1	1.2489 (16)	C6—H6	0.93
C1—N1	1.3104 (18)	C7—O3	1.2523 (16)
C1—C2	1.4932 (19)	C7—C8	1.4687 (17)
C2—N2	1.3438 (16)	C8—O4	1.2495 (16)
C2—C3	1.3762 (18)	N1—H1A	0.855 (16)
C3—C4	1.385 (2)	N1—H1B	0.851 (17)
C3—H3	0.93	N2—Cu1	1.9724 (11)
C4—C5	1.375 (2)	O1—Cu1	1.9976 (10)
C4—H4	0.93	O2—Cu1	2.3342 (14)
C5—C6	1.385 (2)	O2—H2A	0.807 (17)
C5—H5	0.93	O2—H2B	0.816 (16)
C6—N2	1.3314 (18)
O1—C1—N1	122.56 (13)	C5—C6—H6	119.0
O1—C1—C2	118.50 (11)	O3—C7—C8	135.81 (13)
N1—C1—C2	118.94 (12)	O4—C8—C7	135.52 (13)
N2—C2—C3	122.03 (12)	C1—N1—H1A	124.5 (15)
N2—C2—C1	112.57 (11)	C1—N1—H1B	117.3 (18)
C3—C2—C1	125.40 (12)	H1A—N1—H1B	118 (2)
C2—C3—C4	118.68 (13)	C6—N2—C2	119.16 (12)
C2—C3—H3	120.7	C6—N2—Cu1	127.34 (9)
C4—C3—H3	120.7	C2—N2—Cu1	113.48 (9)
C5—C4—C3	119.31 (13)	C1—O1—Cu1	112.95 (9)
C5—C4—H4	120.3	Cu1—O2—H2A	129.6 (19)
C3—C4—H4	120.3	Cu1—O2—H2B	116.4 (16)
C4—C5—C6	118.86 (14)	H2A—O2—H2B	113 (3)
C4—C5—H5	120.6	N2—Cu1—O1	82.17 (4)
C6—C5—H5	120.6	N2—Cu1—O2	89.46 (5)
N2—C6—C5	121.96 (13)	O1—Cu1—O2	85.19 (5)
N2—C6—H6	119.0
O1—C1—C2—N2	−1.74 (19)	C3—C2—N2—C6	−0.5 (2)
N1—C1—C2—N2	178.17 (13)	C1—C2—N2—C6	178.82 (12)
O1—C1—C2—C3	177.57 (13)	C3—C2—N2—Cu1	177.84 (11)
N1—C1—C2—C3	−2.5 (2)	C1—C2—N2—Cu1	−2.83 (14)
N2—C2—C3—C4	0.0 (2)	N1—C1—O1—Cu1	−174.61 (12)
C1—C2—C3—C4	−179.29 (14)	C2—C1—O1—Cu1	5.30 (16)
C2—C3—C4—C5	0.4 (2)	C6—N2—Cu1—O1	−177.49 (14)
C3—C4—C5—C6	−0.2 (3)	C2—N2—Cu1—O1	4.32 (10)
C4—C5—C6—N2	−0.4 (3)	C6—N2—Cu1—O2	97.30 (13)
O3—C7—C8—O4	−1.3 (3)	C2—N2—Cu1—O2	−80.89 (10)
C5—C6—N2—C2	0.7 (2)	C1—O1—Cu1—N2	−5.29 (10)
C5—C6—N2—Cu1	−177.37 (12)	C1—O1—Cu1—O2	84.83 (11)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N1—H1A···O3^i	0.86 (2)	1.99 (2)	2.8324 (16)	168 (2)
N1—H1B···O4^ii	0.85 (2)	2.53 (2)	3.0678 (19)	122 (2)
O2—H2A···O4^iii	0.81 (2)	1.98 (2)	2.7659 (17)	165 (3)
O2—H2B···O3^ii	0.82 (2)	2.05 (2)	2.8264 (16)	158 (2)
C6—H6···Cg1^iv	0.93	3.13	3.8251 (17)	133

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