Bis­(pyrazine-2-carbox­amide)­bis­(tri­fluoro­methanesulfonato)copper(II) monohydrate

The copper(II) ion in [Cu(C₅H₅N₃O)₂(CF₃SO₃)₂]·H₂O lies on a center of symmetry and is coordinated by two pyrazine­carbox­amide ligands in a square-planar geometry with Cu-O and Cu-N distances of 1.9445 (14) and 1.9680 (17) Å, respectively. The Cu(C₅H₅N₃O)₂ unit is approximately planar, with an average atomic deviation of 0.057 (4) Å from the least-squares plane. Each copper center is further coordinated, in the axial direction, by two symmetry-equivalent O atoms from tri­fluoro­methane­sulfonate anions with a Cu-O distance of 2.4871 (17) Å, giving the copper(II) ion a Jahn-Teller distorted-octahedral geometry.

Key indicators

• Single-crystal X-ray study
• T = 295 K
• Mean [sigma](C-C) = 0.003 Å
• R factor = 0.037
• wR factor = 0.105
• Data-to-parameter ratio = 15.3

checkCIF results

No syntax errors found

ADDSYM reports no extra symmetry

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S1. Comment

The multifunctionality of the pyrazine-2-carboxamide (pyca) ligand offers interesting possibilities in crystal engineering, owing to its chelating properties in addition to its potential as a linker molecule between metal centers. In this contribution, we present the crystal structure of bis(pyrazine-2-carboxamide)bis(trifluoromethanesulphonato)copper(II) monohydrate, (I). The copper(II) ion lies on a center of symmetry and is coordinated by two pyca ligands in a square-planar geometry (Figure 1). The Cu²⁺ ion chelates the pyca ligand via N1 and O1 to form a five-membered chelate ring. The N1—O1—Cu1—N1ⁱ—O1ⁱ moiety [symmetry code (i): -x, -y, -z] is strictly planar. The average atomic deviation from the least-squares plane defined by all the non-H atoms of the pyca ligand is 0.024 (4) Å. The ligand plane forms an angle of 5.83 (9) ° with the former plane, which results in a copper out-of-plane distance from the pyca ligand of 0.1422 (1) Å.

The changes of the intermolecular geometry of the pyca molecule upon coordination with the Cu²⁺ cation are insignificant, with all distances within one standard deviation of the average value for the four crystalline polymorphs of pyca structurally determined (Allen & Kennard, 1993). Each copper center is further coordinated, in the axial direction, by two symmetry-equivalent oxygen atoms from trifluoromethanesulfonate anions. The geometry of the copper ion can thus be considered as a Jahn–Teller distorted octahedron. The water molecule lies on a twofold axis and forms four hydrogen bonds by accepting two symmetry-equivalent protons from the amide groups and by donating two relatively weak, equivalent hydrogen bonds to trifluoromethanesulfonate oxygen atoms. The hydrogen-bond pattern is completed by a relatively weak hydrogen bond between the amide group and the trifluoromethanesulfonate O11 atom. The packing in the unit cell, viewed along the b axis, is shown in Fig. 2.

In the closely related bis(pyca)copper(II) perchlorate (Sekisaki, 1973), the copper center is chelated by two symmetry-equivalent pyca ligands with Cu—O and Cu—N distances of 1.964 (4) and 1.999 (6) Å, respectively. In this case, however, the perchlorate anions are non-coordinating, and the axial positions of the copper ion are occupied by the ring N atom, corresponding to N4 of the title compound, of adjacent Cu(pyca)₂ complexes, resulting in a two-dimensional square-grid network. In acetylacetonato(pyca)copper(II) perchlorate monohydrate (Zhong et al., 1990), which has a similar bidentate coordination mode to the title compound, the Cu—O and Cu—N distances are 2.008 (6) and 1.992 (3) Å, respectively. Interestingly, in this case the perchlorate anions occupy axial positions, with Cu—O distances of 2.543 (9) and 2.871 (4) Å, and each perchlorate anion bridges two adjacent copper centers to form extended chains.

S2. Experimental

A mixture of Cu(H₂O)₆(CF₃SO₃)₂ (1 mmol) and pyrazine-3-carboxamide (4 mmol) in water/ethanol (50:50) was stirred while boiling. The solution was allowed to evaporate slowly, which afforded X-ray quality crystals. The chosen crystals were coated with a hydrocarbon oil and mounted on a glass fibre

Computing details

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

Figures

	Fig. 1. ORTEP (Johnson, 1976) drawing of the molecular structure of the title compound, with displacement ellipsoids drawn at the 30% probability level for all non-H atoms.
	Fig. 2. The packing in the unit cell, viewed along the b axis. Hydrogen atoms and oxygen and flourine atoms of the trifluoromethanesulfonate anions are omitted for clarity.

bis(pyrazine-2-caboxamide)bis(trifluoromethanesulphonato)copper(II) monohydrate

Crystal data

[Cu(C5H5N3O)2(CF3SO3)2]·H2O	F(000) = 1252
Mr = 625.94	Dx = 1.794 Mg m^−3
Orthorhombic, Pbcn	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2n 2ab	Cell parameters from 1907 reflections
a = 8.9014 (7) Å	θ = 2.2–28.0°
b = 13.7809 (11) Å	µ = 1.23 mm^−1
c = 18.8910 (15) Å	T = 295 K
V = 2317.3 (3) Å^3	Prism, blue
Z = 4	0.30 × 0.25 × 0.18 mm

Data collection

Bruker SMART CCD diffractometer	2738 independent reflections
Radiation source: fine-focus sealed tube	1907 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.035
ω scans	θmax = 28.0°, θmin = 2.2°
Absorption correction: multi-scan (SADABS; Bruker, 1998)	h = −11→11
Tmin = 0.710, Tmax = 0.809	k = −18→18
13434 measured reflections	l = −24→16

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)] = 0.037	H atoms treated by a mixture of independent and constrained refinement
wR(F^2) = 0.105	w = 1/[σ^2(Fo^2) + (0.0773P)^2] where P = (Fo^2 + 2Fc^2)/3
S = 0.89	(Δ/σ)max < 0.001
2738 reflections	Δρmax = 0.53 e Å^−3
179 parameters	Δρmin = −0.54 e Å^−3
0 restraints	Extinction correction: SHELXL, Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0034 (5)

Special details

Experimental. A hemisphere of data (1291 frames) was collected for each structure (0.3° frame width) with 40 s exposure time. The crystal-detector distance was 4.74 cm. Water- and amide-H atoms were located on difference Fourier maps and isotropically refined with no restraints. Carbon-H atoms were generated in ideal positions and were refined as riding on their respective C atoms.

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
Cu1	0.0000	0.0000	0.0000	0.03429 (14)
O1	0.04724 (18)	−0.06811 (10)	0.08735 (7)	0.0350 (3)
O2	−0.5000	0.2722 (2)	0.2500	0.0551 (7)
N1	0.10327 (19)	0.10799 (12)	0.04774 (9)	0.0325 (4)
N2	0.1408 (2)	−0.04973 (16)	0.19627 (10)	0.0398 (5)
N4	0.2283 (3)	0.24654 (14)	0.13453 (11)	0.0564 (6)
C2	0.1308 (3)	0.19622 (16)	0.02345 (12)	0.0410 (5)
H2	0.1076	0.2119	−0.0232	0.049*
C3	0.1943 (3)	0.26512 (17)	0.06748 (13)	0.0497 (6)
H3	0.2139	0.3266	0.0495	0.060*
C5	0.2009 (3)	0.15719 (17)	0.15810 (12)	0.0444 (6)
H5	0.2239	0.1418	0.2048	0.053*
C6	0.1392 (2)	0.08705 (15)	0.11497 (11)	0.0314 (4)
C7	0.1054 (2)	−0.01598 (14)	0.13424 (11)	0.0308 (4)
S10	−0.30289 (7)	0.07843 (5)	0.11977 (3)	0.04407 (19)
O10	−0.4075 (3)	0.1563 (2)	0.12653 (13)	0.0913 (8)
O11	−0.2040 (2)	0.06537 (15)	0.17885 (9)	0.0657 (5)
O12	−0.2302 (2)	0.07279 (14)	0.05245 (8)	0.0560 (5)
C10	−0.4188 (5)	−0.0307 (4)	0.1209 (2)	0.0909 (12)
F10	−0.5260 (4)	−0.0222 (3)	0.0741 (2)	0.1633 (16)
F11	−0.4921 (3)	−0.0372 (3)	0.1791 (2)	0.1665 (14)
F12	−0.3395 (5)	−0.1058 (2)	0.1120 (2)	0.199 (2)
H1B	0.171 (3)	−0.0123 (18)	0.2264 (15)	0.038 (7)*
H1A	0.121 (3)	−0.109 (2)	0.2014 (14)	0.049 (8)*
H2B	−0.486 (4)	0.238 (3)	0.2174 (17)	0.083 (12)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1	0.0485 (3)	0.0261 (2)	0.0283 (2)	−0.00458 (15)	−0.00822 (15)	0.00020 (13)
O1	0.0467 (8)	0.0272 (7)	0.0311 (8)	−0.0013 (6)	−0.0067 (6)	−0.0007 (6)
O2	0.0707 (19)	0.0436 (15)	0.0512 (17)	0.000	−0.0115 (14)	0.000
N1	0.0369 (9)	0.0286 (9)	0.0319 (9)	−0.0028 (7)	−0.0022 (7)	0.0010 (6)
N2	0.0557 (13)	0.0310 (10)	0.0327 (10)	−0.0034 (9)	−0.0088 (9)	0.0012 (8)
N4	0.0833 (17)	0.0378 (12)	0.0482 (12)	−0.0169 (11)	−0.0156 (11)	−0.0006 (8)
C2	0.0519 (14)	0.0359 (11)	0.0352 (11)	−0.0078 (10)	−0.0035 (10)	0.0050 (9)
C3	0.0667 (16)	0.0322 (12)	0.0502 (14)	−0.0130 (11)	−0.0067 (12)	0.0047 (10)
C5	0.0587 (14)	0.0394 (12)	0.0351 (12)	−0.0095 (11)	−0.0100 (10)	−0.0003 (9)
C6	0.0325 (10)	0.0311 (10)	0.0305 (10)	0.0004 (9)	−0.0004 (8)	−0.0009 (8)
C7	0.0308 (10)	0.0303 (10)	0.0314 (10)	0.0030 (8)	0.0002 (8)	−0.0004 (8)
S10	0.0451 (3)	0.0534 (4)	0.0338 (3)	0.0106 (3)	0.0002 (2)	0.0030 (2)
O10	0.0956 (17)	0.0975 (18)	0.0809 (17)	0.0526 (15)	0.0113 (13)	0.0001 (13)
O11	0.0740 (13)	0.0813 (15)	0.0419 (10)	0.0027 (11)	−0.0177 (9)	0.0049 (9)
O12	0.0518 (11)	0.0777 (13)	0.0386 (9)	0.0065 (9)	0.0064 (8)	0.0100 (8)
C10	0.077 (3)	0.117 (3)	0.078 (3)	−0.032 (3)	0.006 (2)	0.002 (2)
F10	0.134 (2)	0.224 (4)	0.131 (3)	−0.089 (3)	−0.050 (2)	0.009 (2)
F11	0.132 (2)	0.243 (4)	0.124 (3)	−0.070 (2)	0.0428 (18)	0.057 (3)
F12	0.210 (4)	0.0652 (17)	0.322 (5)	−0.043 (2)	0.100 (3)	−0.021 (2)

Geometric parameters (Å, º)

Cu1—O1	1.9445 (14)	C2—H2	0.9300
Cu1—N1	1.9680 (17)	C3—H3	0.9300
Cu1—O12	2.4871 (17)	C5—C6	1.378 (3)
O1—C7	1.253 (2)	C5—H5	0.9300
O2—H2B	0.79 (3)	C6—C7	1.496 (3)
N1—C2	1.323 (3)	S10—O12	1.4291 (17)
N1—C6	1.341 (3)	S10—O11	1.4330 (18)
N2—C7	1.299 (3)	S10—O10	1.426 (2)
N2—H1B	0.81 (3)	S10—C10	1.824 (5)
N2—H1A	0.84 (3)	C10—F12	1.264 (6)
N4—C3	1.327 (3)	C10—F11	1.281 (5)
N4—C5	1.332 (3)	C10—F10	1.306 (5)
C2—C3	1.383 (3)
O1^i—Cu1—O1	180.00 (8)	N4—C5—C6	121.6 (2)
O1^i—Cu1—N1	97.17 (6)	N4—C5—H5	119.2
O1—Cu1—N1	82.83 (6)	C6—C5—H5	119.2
N1—Cu1—N1^i	180.00 (11)	N1—C6—C5	120.26 (19)
O1—Cu1—O12^i	88.01 (6)	N1—C6—C7	112.74 (17)
N1—Cu1—O12^i	95.90 (7)	C5—C6—C7	127.0 (2)
O1—Cu1—O12	91.99 (6)	O1—C7—N2	122.17 (19)
N1—Cu1—O12	84.10 (7)	O1—C7—C6	117.09 (18)
O12^i—Cu1—O12	180.00 (12)	N2—C7—C6	120.7 (2)
C7—O1—Cu1	114.37 (13)	O12—S10—O11	114.07 (12)
C2—N1—C6	118.82 (18)	O12—S10—O10	114.60 (13)
C2—N1—Cu1	128.53 (15)	O11—S10—O10	115.21 (14)
C6—N1—Cu1	112.50 (13)	O12—S10—C10	102.81 (17)
C7—N2—H1B	119.0 (17)	O11—S10—C10	103.59 (17)
C7—N2—H1A	113.6 (18)	O10—S10—C10	104.5 (2)
H1B—N2—H1A	127 (3)	S10—O12—Cu1	138.56 (10)
C3—N4—C5	117.1 (2)	F12—C10—F11	110.0 (5)
N1—C2—C3	119.9 (2)	F12—C10—F10	113.1 (5)
N1—C2—H2	120.1	F11—C10—F10	102.4 (4)
C3—C2—H2	120.1	F12—C10—S10	110.9 (3)
N4—C3—C2	122.3 (2)	F11—C10—S10	110.8 (4)
N4—C3—H3	118.8	F10—C10—S10	109.4 (4)
C2—C3—H3	118.8

Symmetry code: (i) −x, −y, −z.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N2—H1B···O11^ii	0.81 (3)	2.11 (3)	2.898 (3)	164 (3)
N2—H1A···O2^iii	0.84 (3)	2.16 (3)	2.936 (3)	153 (2)
O2—H2B···O10	0.79 (3)	2.17 (3)	2.945 (3)	169 (3)

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