Bis­[2-(pyrazol-3-yl)­phenolato-κ²N²,O]copper(II) dimethanol solvate

The title compound, [Cu(C₉H₇N₂O)₂]·2CH₃OH, contains a crystallographically centrosymmetric near-regular square planar Cu^II centre with trans-disposed chelating ligands. The complex mol­ecules associate into a one-dimensional polymeric chain via hydrogen bonding to the solvent mol­ecules.

S1. Comment

We have recently described that complexation of CuCl₂ or CuBr₂ by 3{5}-tertbutylpyrazole in basic MeOH leads to a novel heptacopper aggregate structure, which is templated by N—H···X (X^- = Cl^-, Br^-) hydrogen bonding between the pyrazole ligands and non-coordinated halide anions (Liu et al., 2001). As an extension of this work, we were keen to examine the Cu(II) chemistry of pyrazole ligands containing additional hydrogen-bonding functionality, in addition to the N—H group of the pyrazole ring. 2-(Pyrazol-3-yl)phenol(HL) is one such ligand that is readily available (Catalan et al., 1992), and we now report the structure of the mononuclear complex [CuL₂]·2CH₃OH (I). No other complexes of L^- have been previously crystallographically characterized, although the crystal structure of one complex of the closely related ligand 2-(5-methylpyrazol-3-yl)phenol (HL'), [FeL'₂(CH₃OH)₂]NO₃·CH₃OH, has been reported (Ainscough et al., 1980).

The asymmetric unit of the crystals contains half a complex molecule, with Cu1 lying on the crystallographic inversion centre at 1/2, 1/2, 1/2, together with one molecule of methanol. As in [FeL'₂(CH₃OH)₂]NO₃·CH₃OH (Ainscough et al., 1980), the L^- ligands in I chelate to the Cu ion through their pyrazole N and phenoxide O donors, giving a four-coordinate Cu(II) centre with a trans-N₂O₂ donor set. The coordination geometry at Cu1 is strictly planar by symmetry, and is almost perfectly square. The Cu(II) ion stands proud of the least squares plane of the chelating ligand, by 0.5784 (13) Å. This is also manifested in the dihedral angle between the square plane of donors at Cu1 [Cu1, N2, O13, N2ⁱ, O13ⁱ] and the least squares plane of the L^- ligand [N2–O13], which is 24.73 (7)°. The pyrazole and phenoxide moieties of the ligand are twisted with respect to each other, with the dihedral angle between the least squares planes [N2–C7] and [C8–O13] being 16.37 (11)°.

The methanol molecule accepts a hydrogen bond from the L^- pyrrolic N—H group, and donates a hydrogen bond to the phenoxide O-donor of a neighbouring molecule related by x, y, 1 - z. This affords a one-dimensional polymeric chain of hydrogen-bonded molecules, running parallel to the z-axis of the unit cell. Adjacent chains are linked by a π–π interaction between the phenyl rings C7–C12 and C7ⁱⁱⁱ–C12ⁱⁱⁱ (related by -x, 1 - y, 1 - z). The interacting rings are strictly coplanar by symmetry and are separated by 3.410 (5) Å, with their centroids being offset by 1.24 Å. These parameters imply a π–π interaction that is only weakly electrostatically attractive (Hunter & Sanders, 1990).

S2. Experimental

A mixture of 2-(pyrazol-3-yl)phenol (0.32 g, 2.0 mmol; Catalan et al., 1992), CuBr₂ (0.22 g, 1.0 mmol) and NaOH (0.040 g, 1 mmol) in MeOH (50 cm³) was stirred at room temperature for 16 hrs, yielding a brown solution. Concentration of this solution to about half its original volume afforded a dark precipitate, which was removed by filtration. Storage of the filtrate at 263 K afforded dark brown plates, which slowly degraded in vacuo. The dried material reproducibly analyses for [CuL₂].xCH₃OH.(2 - x)H₂O (x = ca 1/2). Found C, 53.4; H, 4.5; N, 12.9%. Calcd for C₁₈H₁₄CuN₄O₂·1.5CH₃OH·0.5H₂O C, 53.4; H, 4.8; N, 12.8%.

S3. Refinement

All H atoms were located in the Fourier difference map and allowed to refine freely. Refined C—H distances ranged from 0.88 (3)–1.02 (4) Å, while N3—H3 = 0.88 (3) and O15—H15 = 0.75 (3) Å.

Computing details

Data collection: COLLECT (Nonius, 1999); cell refinement: DENZO-SMN (Otwinowski & Minor, 1996); data reduction: DENZO-SMN; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEX (McArdle, 1995); software used to prepare material for publication: local program.

Figures

Fig. 1. A view of the title compound with 50% probability displacement ellipsoids, showing the atom numbering scheme employed. H atoms have arbitrary radii. [Symmetry codes: (i) 1 - x, 1 - y, 1 - z; (ii) x, y, 1 - z].

Bis[2-(pyrazol-3-yl)phenolato]copper(II) methanol disolvate

Crystal data

C18H14CuN4O2·2(CH4O)	F(000) = 462
Mr = 445.96	Dx = 1.559 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
a = 7.5210 (2) Å	Cell parameters from 10193 reflections
b = 15.6270 (4) Å	θ = 2.8–27.5°
c = 8.3657 (3) Å	µ = 1.19 mm^−1
β = 105.000 (1)°	T = 150 K
V = 949.72 (5) Å^3	Plate, brown
Z = 2	0.19 × 0.15 × 0.03 mm

Data collection

Nonius KappaCCD diffractometer	2172 independent reflections
Radiation source: fine-focus sealed tube	1952 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.038
Detector resolution: 9.091 pixels mm^-1	θmax = 27.5°, θmin = 2.8°
Area detector scans	h = −9→9
Absorption correction: multi-scan (SORTAV; Blessing, 1995)	k = −20→20
Tmin = 0.806, Tmax = 0.965	l = −10→10
10193 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)] = 0.034	All H-atom parameters refined
wR(F^2) = 0.093	w = 1/[σ^2(Fo^2) + (0.053P)^2 + 0.359P] where P = (Fo^2 + 2Fc^2)/3
S = 1.06	(Δ/σ)max = 0.001
2172 reflections	Δρmax = 0.37 e Å^−3
178 parameters	Δρmin = −0.51 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: 0.032 (5)

Special details

Experimental. Detector set at 30 mm from sample with different 2theta offsets 1 degree phi exposures for chi=0 degree settings 1 degree omega exposures for chi=90 degree settings

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. Structure solution was achieved by direct methods using SHELXS97 (Sheldrick, 1990), while least squares refinement used SHELXL97 (Sheldrick, 1997). No disorder was detected during refinement. All non-H atoms were refined anisotropically, and no restraints were applied.

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

	x	y	z	Uiso*/Ueq
Cu1	0.5000	0.5000	0.5000	0.02096 (15)
N2	0.3506 (2)	0.41544 (9)	0.35599 (18)	0.0236 (3)
N3	0.3799 (2)	0.38621 (10)	0.21270 (18)	0.0264 (3)
H3	0.462 (4)	0.4056 (16)	0.163 (3)	0.037 (6)*
C4	0.2536 (3)	0.32732 (13)	0.1430 (2)	0.0311 (4)
H4	0.267 (3)	0.2998 (16)	0.044 (3)	0.038 (6)*
C5	0.1370 (3)	0.31699 (13)	0.2437 (2)	0.0304 (4)
H5	0.034 (3)	0.2756 (16)	0.229 (3)	0.035 (6)*
C6	0.2005 (2)	0.37442 (11)	0.3765 (2)	0.0234 (4)
C7	0.1216 (2)	0.39339 (11)	0.5144 (2)	0.0230 (4)
C8	0.2203 (2)	0.43845 (11)	0.6562 (2)	0.0230 (4)
C9	0.1342 (2)	0.45397 (12)	0.7839 (2)	0.0266 (4)
H9	0.193 (3)	0.4867 (14)	0.877 (3)	0.026 (6)*
C10	−0.0437 (3)	0.42674 (12)	0.7724 (2)	0.0284 (4)
H10	−0.093 (3)	0.4383 (15)	0.862 (3)	0.033 (6)*
C11	−0.1427 (3)	0.38374 (12)	0.6313 (2)	0.0282 (4)
H11	−0.274 (3)	0.3651 (17)	0.621 (3)	0.041 (7)*
C12	−0.0601 (3)	0.36810 (12)	0.5050 (2)	0.0273 (4)
H12	−0.129 (3)	0.3408 (15)	0.411 (3)	0.034 (6)*
O13	0.39371 (16)	0.46636 (9)	0.67637 (15)	0.0251 (3)
C14	0.6207 (4)	0.31413 (15)	−0.0520 (3)	0.0429 (5)
H14A	0.638 (5)	0.282 (2)	0.057 (5)	0.080 (10)*
H14B	0.526 (5)	0.289 (2)	−0.121 (4)	0.064 (9)*
H14C	0.723 (5)	0.307 (2)	−0.087 (4)	0.068 (10)*
O15	0.5817 (2)	0.40058 (9)	−0.02642 (17)	0.0306 (3)
H15	0.533 (4)	0.4182 (18)	−0.110 (4)	0.040 (7)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cu1	0.0228 (2)	0.0222 (2)	0.0183 (2)	−0.00240 (10)	0.00616 (13)	−0.00010 (10)
N2	0.0268 (7)	0.0240 (7)	0.0211 (7)	−0.0006 (6)	0.0085 (5)	−0.0005 (6)
N3	0.0319 (8)	0.0286 (8)	0.0208 (7)	−0.0018 (6)	0.0104 (6)	−0.0030 (6)
C4	0.0383 (10)	0.0311 (9)	0.0238 (9)	−0.0046 (8)	0.0077 (8)	−0.0047 (7)
C5	0.0344 (10)	0.0304 (9)	0.0258 (9)	−0.0073 (8)	0.0070 (7)	−0.0033 (7)
C6	0.0258 (8)	0.0219 (8)	0.0217 (8)	−0.0005 (6)	0.0044 (6)	0.0016 (6)
C7	0.0240 (8)	0.0226 (8)	0.0231 (8)	−0.0003 (6)	0.0070 (6)	0.0038 (6)
C8	0.0237 (8)	0.0227 (8)	0.0225 (8)	−0.0005 (6)	0.0059 (6)	0.0042 (6)
C9	0.0295 (9)	0.0279 (9)	0.0231 (8)	−0.0004 (7)	0.0079 (7)	0.0005 (7)
C10	0.0298 (9)	0.0294 (9)	0.0301 (9)	0.0025 (7)	0.0149 (7)	0.0041 (7)
C11	0.0235 (8)	0.0269 (9)	0.0348 (10)	0.0002 (7)	0.0088 (7)	0.0068 (7)
C12	0.0262 (9)	0.0257 (9)	0.0291 (9)	−0.0028 (7)	0.0056 (7)	0.0028 (7)
O13	0.0237 (6)	0.0329 (7)	0.0192 (6)	−0.0041 (5)	0.0062 (5)	0.0009 (5)
C14	0.0498 (14)	0.0331 (11)	0.0526 (14)	0.0054 (10)	0.0254 (12)	0.0043 (10)
O15	0.0360 (7)	0.0325 (7)	0.0224 (7)	0.0030 (6)	0.0061 (6)	0.0015 (5)

Geometric parameters (Å, º)

Cu1—N2	1.9390 (15)	C8—C9	1.406 (3)
Cu1—O13	1.9243 (12)	C9—C10	1.384 (3)
N2—C6	1.347 (2)	C9—H9	0.94 (3)
N2—N3	1.353 (2)	C10—C11	1.395 (3)
N3—C4	1.343 (2)	C10—H10	0.94 (2)
N3—H3	0.88 (3)	C11—C12	1.379 (3)
C4—C5	1.374 (3)	C11—H11	1.01 (3)
C4—H4	0.96 (3)	C12—H12	0.93 (2)
C5—C6	1.412 (2)	C14—O15	1.411 (3)
C5—H5	0.99 (3)	C14—H14A	1.02 (4)
C6—C7	1.458 (3)	C14—H14B	0.88 (3)
C7—C12	1.405 (3)	C14—H14C	0.90 (4)
C7—C8	1.414 (2)	O15—H15	0.75 (3)
C8—O13	1.344 (2)
O13^i—Cu1—O13	180	O13—C8—C7	123.29 (16)
O13—Cu1—N2	90.07 (6)	C9—C8—C7	118.58 (16)
O13—Cu1—N2^i	89.93 (6)	C10—C9—C8	121.44 (17)
N2—Cu1—N2^i	180	C10—C9—H9	117.5 (15)
C6—N2—N3	106.65 (14)	C8—C9—H9	120.9 (16)
C6—N2—Cu1	127.96 (12)	C9—C10—C11	120.11 (17)
N3—N2—Cu1	125.39 (12)	C9—C10—H10	117.5 (14)
C4—N3—N2	110.90 (16)	C11—C10—H10	122.4 (14)
C4—N3—H3	122.3 (17)	C12—C11—C10	119.09 (17)
N2—N3—H3	126.5 (17)	C12—C11—H11	120.6 (14)
N3—C4—C5	107.82 (17)	C10—C11—H11	120.3 (14)
N3—C4—H4	117.5 (14)	C11—C12—C7	122.11 (18)
C5—C4—H4	134.5 (15)	C11—C12—H12	118.0 (14)
C4—C5—C6	105.59 (17)	C7—C12—H12	119.9 (14)
C4—C5—H5	127.1 (14)	C8—O13—Cu1	125.08 (11)
C6—C5—H5	127.2 (14)	O15—C14—H14A	109 (2)
N2—C6—C5	109.03 (16)	O15—C14—H14B	111 (2)
N2—C6—C7	122.02 (16)	H14A—C14—H14B	105 (3)
C5—C6—C7	128.90 (17)	O15—C14—H14C	114 (2)
C12—C7—C8	118.64 (17)	H14A—C14—H14C	108 (3)
C12—C7—C6	119.17 (16)	H14B—C14—H14C	110 (3)
C8—C7—C6	122.17 (16)	C14—O15—H15	106 (2)
O13—C8—C9	118.13 (15)

Symmetry code: (i) −x+1, −y+1, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N3—H3···O15	0.88 (3)	2.02 (3)	2.815 (2)	150 (2)
O15—H15···O13^ii	0.75 (3)	1.97 (3)	2.724 (2)	177 (3)

Symmetry code: (ii) x, y, z−1.