The title compound, [CuBr(C6H7NO)2]Br·H2O, is an ionic mononuclear complex in which the [CuBr(C6H7NO)2]+ cation possesses distorted square-pyramidal geometry. The CuII centre is coordinated by two neutral 2-(pyridin-2-yl)methanol (2-pyMeOH) ligands and a terminal bromide ligand. The 2-pyMeOH ligands are coordinated in a bidentate chelating manner through the pyridine N and hydroxy O atoms, forming a five-membered chelate ring with the CuII centre. The planes of the pyridine rings are twisted by 58.71 (14)° with respect to each other. The charge is balanced by a noncoordinating bromide anion which, together with a solvent water molecule, links the components through hydrogen bonds into infinite chains propagating along the a axis. The mononuclear cations appear to associate in pairs through weak interactions between the metal atom of one cation and the halogen atom of an adjacent cation.
Supporting information
CCDC reference: 950435
CuBr2 (120 mg, 5.4 mmol) was dissolved in methanol (15 ml) while mixing and
heating to boiling. Itaconic acid (2-methylidenebutanedioic acid; 70 mg, 5.4 mmol) and 2-pyMeOH (0,15 ml, 1.5 mmol) were added. The resulting solution was
left under ambient conditions for slow evaporation of the solvent.
Turquoise–blue crystals of (I) appeared within a few days.
All C-bound H atoms were initially found in a difference Fourier map, but they
were repositioned at their calculated positions and refined using a riding
model. Aromatic H atoms were permitted to ride, with C—H = 0.93 Å and
Ueq(H) = 1.2Uiso(C), and those of the CH2 group were
constrained, with C—H = 0.97 Å and Ueq(H)=1.2Uiso(C).
The H atoms of the hydroxy groups and the water molecule were positioned from
a difference Fourier map and refined freely.
Data collection: CrysAlis PRO (Agilent, 2011); cell refinement: CrysAlis PRO (Agilent, 2011); data reduction: CrysAlis PRO (Agilent, 2011); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, (2012); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).
Bromidobis[2-(pyridin-2-yl)methanol-
κ2N,
O]copper(II) bromide
monohydrate
top
Crystal data top
[CuBr(C6H7NO)2]Br·H2O | Z = 2 |
Mr = 459.63 | F(000) = 450 |
Triclinic, P1 | Dx = 1.915 Mg m−3 |
Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71073 Å |
a = 7.9681 (6) Å | Cell parameters from 3806 reflections |
b = 9.8543 (6) Å | θ = 2.9–30.4° |
c = 11.1812 (8) Å | µ = 6.39 mm−1 |
α = 74.974 (6)° | T = 150 K |
β = 72.481 (6)° | Prismatic, light blue |
γ = 76.590 (6)° | 0.3 × 0.2 × 0.2 mm |
V = 797.24 (10) Å3 | |
Data collection top
Agilent SuperNova (Dual, Cu at zero, Atlas) diffractometer | 3668 independent reflections |
Radiation source: SuperNova (Mo) X-ray Source | 3086 reflections with I > 2σ(I) |
Mirror monochromator | Rint = 0.037 |
Detector resolution: 10.4933 pixels mm-1 | θmax = 27.5°, θmin = 2.9° |
ω scans | h = −10→9 |
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2011) | k = −12→12 |
Tmin = 0.073, Tmax = 1.000 | l = −14→14 |
6592 measured reflections | |
Refinement top
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.041 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.092 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.04 | w = 1/[σ2(Fo2) + (0.0382P)2] where P = (Fo2 + 2Fc2)/3 |
3668 reflections | (Δ/σ)max = 0.001 |
197 parameters | Δρmax = 0.92 e Å−3 |
0 restraints | Δρmin = −0.85 e Å−3 |
Crystal data top
[CuBr(C6H7NO)2]Br·H2O | γ = 76.590 (6)° |
Mr = 459.63 | V = 797.24 (10) Å3 |
Triclinic, P1 | Z = 2 |
a = 7.9681 (6) Å | Mo Kα radiation |
b = 9.8543 (6) Å | µ = 6.39 mm−1 |
c = 11.1812 (8) Å | T = 150 K |
α = 74.974 (6)° | 0.3 × 0.2 × 0.2 mm |
β = 72.481 (6)° | |
Data collection top
Agilent SuperNova (Dual, Cu at zero, Atlas) diffractometer | 3668 independent reflections |
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2011) | 3086 reflections with I > 2σ(I) |
Tmin = 0.073, Tmax = 1.000 | Rint = 0.037 |
6592 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.041 | 0 restraints |
wR(F2) = 0.092 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.04 | Δρmax = 0.92 e Å−3 |
3668 reflections | Δρmin = −0.85 e Å−3 |
197 parameters | |
Special details top
Experimental. Abdorption correction: CrysAlisPro, Agilent Technologies,
Version 1.171.35.11 (release 16-05-2011 CrysAlis171 .NET)
(compiled May 16 2011,17:55:39)
Empirical absorption correction using spherical harmonics,
implemented in SCALE3 ABSPACK scaling algorithm. |
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are
estimated using the full covariance matrix. The cell s.u.'s are taken into
account individually in the estimation of s.u.'s in distances, angles and
torsion angles; correlations between s.u.'s in cell parameters are only used
when they are defined by crystal symmetry. An approximate (isotropic)
treatment of cell s.u.'s is used for estimating s.u.'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 >
2σ(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 (Å2) top | x | y | z | Uiso*/Ueq | |
Br1 | 0.69276 (5) | 0.11173 (4) | 0.41782 (4) | 0.02072 (12) | |
Br2 | 0.82213 (5) | 0.33174 (4) | −0.01707 (4) | 0.02657 (13) | |
Cu1 | 0.41848 (6) | 0.15156 (4) | 0.35337 (4) | 0.01644 (13) | |
O2B | 0.1749 (4) | 0.1436 (3) | 0.3342 (3) | 0.0216 (6) | |
O2A | 0.4565 (4) | 0.3461 (3) | 0.1964 (3) | 0.0233 (6) | |
O1W | 1.0781 (5) | 0.3461 (4) | 0.1580 (3) | 0.0412 (9) | |
H1W | 1.120 (7) | 0.408 (5) | 0.117 (4) | 0.033 (15)* | |
H2W | 1.000 (9) | 0.344 (6) | 0.122 (5) | 0.065 (19)* | |
N21 | 0.4958 (4) | 0.0118 (3) | 0.2393 (3) | 0.0165 (6) | |
C22 | 0.3623 (5) | −0.0388 (4) | 0.2233 (3) | 0.0186 (8) | |
C25 | 0.7064 (6) | −0.1302 (4) | 0.0995 (4) | 0.0284 (9) | |
H25 | 0.8243 | −0.1591 | 0.0573 | 0.034* | |
N11 | 0.3099 (4) | 0.3101 (3) | 0.4460 (3) | 0.0174 (6) | |
C24 | 0.5702 (6) | −0.1840 (4) | 0.0866 (4) | 0.0292 (10) | |
H24 | 0.5952 | −0.2519 | 0.0367 | 0.035* | |
C1B | 0.1767 (5) | 0.0183 (4) | 0.2924 (4) | 0.0243 (9) | |
H1B1 | 0.0985 | 0.0402 | 0.2357 | 0.029* | |
H1B2 | 0.1322 | −0.0536 | 0.3658 | 0.029* | |
C26 | 0.6636 (6) | −0.0318 (4) | 0.1770 (4) | 0.0241 (9) | |
H26 | 0.7551 | 0.0054 | 0.1862 | 0.029* | |
C12 | 0.3498 (5) | 0.4406 (4) | 0.3872 (4) | 0.0212 (8) | |
C14 | 0.1854 (6) | 0.5329 (4) | 0.5740 (4) | 0.0282 (9) | |
H14 | 0.1450 | 0.6081 | 0.6170 | 0.034* | |
C15 | 0.1414 (6) | 0.3995 (4) | 0.6338 (4) | 0.0278 (9) | |
H15 | 0.0698 | 0.3834 | 0.7171 | 0.033* | |
C13 | 0.2896 (6) | 0.5526 (4) | 0.4504 (4) | 0.0273 (9) | |
H13 | 0.3198 | 0.6418 | 0.4090 | 0.033* | |
C1A | 0.4647 (6) | 0.4577 (4) | 0.2527 (4) | 0.0262 (9) | |
H1A1 | 0.4239 | 0.5492 | 0.2029 | 0.031* | |
H1A2 | 0.5871 | 0.4552 | 0.2527 | 0.031* | |
C16 | 0.2069 (5) | 0.2909 (4) | 0.5663 (4) | 0.0234 (8) | |
H16 | 0.1783 | 0.2009 | 0.6060 | 0.028* | |
C23 | 0.3979 (6) | −0.1375 (4) | 0.1472 (4) | 0.0260 (9) | |
H23 | 0.3049 | −0.1722 | 0.1373 | 0.031* | |
H2A | 0.542 (7) | 0.346 (5) | 0.139 (4) | 0.032 (14)* | |
H2B | 0.149 (6) | 0.203 (4) | 0.288 (4) | 0.017 (13)* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
Br1 | 0.0136 (2) | 0.0230 (2) | 0.0271 (2) | 0.00025 (15) | −0.00721 (18) | −0.00840 (16) |
Br2 | 0.0208 (2) | 0.0361 (2) | 0.0236 (2) | −0.00661 (18) | −0.00253 (19) | −0.00954 (18) |
Cu1 | 0.0117 (2) | 0.0178 (2) | 0.0205 (3) | 0.00292 (18) | −0.0042 (2) | −0.00993 (18) |
O2B | 0.0158 (14) | 0.0239 (15) | 0.0269 (16) | 0.0029 (12) | −0.0088 (14) | −0.0101 (13) |
O2A | 0.0216 (16) | 0.0280 (15) | 0.0184 (15) | −0.0041 (12) | 0.0019 (15) | −0.0097 (12) |
O1W | 0.053 (2) | 0.0335 (19) | 0.047 (2) | −0.0148 (18) | −0.032 (2) | 0.0030 (17) |
N21 | 0.0157 (16) | 0.0164 (15) | 0.0160 (15) | 0.0014 (12) | −0.0043 (14) | −0.0043 (12) |
C22 | 0.024 (2) | 0.0152 (18) | 0.0172 (18) | −0.0002 (15) | −0.0082 (18) | −0.0032 (14) |
C25 | 0.029 (2) | 0.030 (2) | 0.017 (2) | 0.0125 (18) | −0.002 (2) | −0.0089 (17) |
N11 | 0.0127 (16) | 0.0185 (16) | 0.0198 (16) | 0.0021 (12) | −0.0024 (15) | −0.0082 (13) |
C24 | 0.048 (3) | 0.018 (2) | 0.022 (2) | 0.0029 (19) | −0.011 (2) | −0.0094 (16) |
C1B | 0.017 (2) | 0.027 (2) | 0.031 (2) | −0.0027 (16) | −0.007 (2) | −0.0103 (18) |
C26 | 0.021 (2) | 0.026 (2) | 0.021 (2) | 0.0029 (17) | −0.0044 (19) | −0.0058 (16) |
C12 | 0.017 (2) | 0.0212 (19) | 0.023 (2) | 0.0016 (16) | −0.0070 (18) | −0.0039 (16) |
C14 | 0.028 (2) | 0.027 (2) | 0.031 (2) | 0.0087 (18) | −0.009 (2) | −0.0185 (18) |
C15 | 0.027 (2) | 0.032 (2) | 0.020 (2) | 0.0051 (18) | −0.001 (2) | −0.0138 (17) |
C13 | 0.029 (2) | 0.0173 (19) | 0.037 (2) | −0.0002 (17) | −0.009 (2) | −0.0094 (17) |
C1A | 0.028 (2) | 0.022 (2) | 0.026 (2) | −0.0070 (17) | 0.000 (2) | −0.0061 (17) |
C16 | 0.021 (2) | 0.022 (2) | 0.024 (2) | 0.0009 (16) | −0.0022 (19) | −0.0063 (16) |
C23 | 0.039 (3) | 0.0183 (19) | 0.025 (2) | −0.0054 (18) | −0.011 (2) | −0.0066 (16) |
Geometric parameters (Å, º) top
Br1—Cu1 | 2.4194 (6) | N11—C16 | 1.339 (5) |
Cu1—N11 | 1.983 (3) | N11—C12 | 1.346 (4) |
Cu1—N21 | 1.987 (3) | C24—C23 | 1.365 (6) |
Cu1—O2B | 2.037 (3) | C24—H24 | 0.9300 |
Cu1—O2A | 2.247 (3) | C1B—H1B1 | 0.9700 |
Cu1—Br1i | 3.2129 (6) | C1B—H1B2 | 0.9700 |
O2B—C1B | 1.425 (4) | C26—H26 | 0.9300 |
O2B—H2B | 0.71 (4) | C12—C13 | 1.379 (5) |
O2A—C1A | 1.424 (4) | C12—C1A | 1.497 (5) |
O2A—H2A | 0.78 (5) | C14—C13 | 1.372 (6) |
O1W—H1W | 0.75 (5) | C14—C15 | 1.383 (6) |
O1W—H2W | 0.84 (6) | C14—H14 | 0.9300 |
N21—C26 | 1.336 (5) | C15—C16 | 1.382 (5) |
N21—C22 | 1.348 (4) | C15—H15 | 0.9300 |
C22—C23 | 1.381 (5) | C13—H13 | 0.9300 |
C22—C1B | 1.501 (5) | C1A—H1A1 | 0.9700 |
C25—C24 | 1.371 (6) | C1A—H1A2 | 0.9700 |
C25—C26 | 1.382 (5) | C16—H16 | 0.9300 |
C25—H25 | 0.9300 | C23—H23 | 0.9300 |
| | | |
N11—Cu1—N21 | 168.98 (12) | C23—C24—H24 | 120.1 |
N11—Cu1—O2B | 90.14 (11) | C25—C24—H24 | 120.1 |
N21—Cu1—O2B | 81.45 (12) | O2B—C1B—C22 | 110.7 (3) |
N11—Cu1—O2A | 77.10 (11) | O2B—C1B—H1B1 | 109.5 |
N21—Cu1—O2A | 96.24 (11) | C22—C1B—H1B1 | 109.5 |
O2B—Cu1—O2A | 93.69 (11) | O2B—C1B—H1B2 | 109.5 |
N11—Cu1—Br1 | 92.47 (8) | C22—C1B—H1B2 | 109.5 |
N21—Cu1—Br1 | 97.41 (9) | H1B1—C1B—H1B2 | 108.1 |
O2B—Cu1—Br1 | 166.09 (9) | N21—C26—C25 | 122.5 (4) |
O2A—Cu1—Br1 | 100.21 (7) | N21—C26—H26 | 118.7 |
N11—Cu1—Br1i | 99.40 (9) | C25—C26—H26 | 118.7 |
N21—Cu1—Br1i | 86.10 (8) | N11—C12—C13 | 120.8 (3) |
O2B—Cu1—Br1i | 79.31 (9) | N11—C12—C1A | 117.4 (3) |
O2A—Cu1—Br1i | 172.24 (8) | C13—C12—C1A | 121.8 (3) |
Br1—Cu1—Br1i | 86.785 (17) | C13—C14—C15 | 119.1 (4) |
C1B—O2B—Cu1 | 111.7 (2) | C13—C14—H14 | 120.5 |
C1B—O2B—H2B | 107 (3) | C15—C14—H14 | 120.5 |
Cu1—O2B—H2B | 110 (3) | C16—C15—C14 | 118.2 (4) |
C1A—O2A—Cu1 | 107.5 (2) | C16—C15—H15 | 120.9 |
C1A—O2A—H2A | 104 (3) | C14—C15—H15 | 120.9 |
Cu1—O2A—H2A | 121 (3) | C14—C13—C12 | 120.2 (4) |
H1W—O1W—H2W | 103 (5) | C14—C13—H13 | 119.9 |
C26—N21—C22 | 118.9 (3) | C12—C13—H13 | 119.9 |
C26—N21—Cu1 | 126.1 (2) | O2A—C1A—C12 | 109.8 (3) |
C22—N21—Cu1 | 115.0 (2) | O2A—C1A—H1A1 | 109.7 |
N21—C22—C23 | 120.8 (4) | C12—C1A—H1A1 | 109.7 |
N21—C22—C1B | 116.2 (3) | O2A—C1A—H1A2 | 109.7 |
C23—C22—C1B | 123.0 (3) | C12—C1A—H1A2 | 109.7 |
C24—C25—C26 | 118.2 (4) | H1A1—C1A—H1A2 | 108.2 |
C24—C25—H25 | 120.9 | N11—C16—C15 | 122.7 (4) |
C26—C25—H25 | 120.9 | N11—C16—H16 | 118.7 |
C16—N11—C12 | 119.0 (3) | C15—C16—H16 | 118.7 |
C16—N11—Cu1 | 122.7 (2) | C24—C23—C22 | 119.7 (4) |
C12—N11—Cu1 | 118.2 (2) | C24—C23—H23 | 120.2 |
C23—C24—C25 | 119.8 (4) | C22—C23—H23 | 120.2 |
Symmetry code: (i) −x+1, −y, −z+1. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O2B—H2B···O1Wii | 0.71 (4) | 1.86 (4) | 2.573 (5) | 175 (5) |
O2A—H2A···Br2 | 0.78 (5) | 2.39 (5) | 3.163 (3) | 173 (4) |
O1W—H1W···Br2iii | 0.75 (5) | 2.60 (5) | 3.319 (4) | 162 (5) |
O1W—H2W···Br2 | 0.84 (6) | 2.44 (6) | 3.271 (3) | 169 (5) |
Symmetry codes: (ii) x−1, y, z; (iii) −x+2, −y+1, −z. |
Experimental details
Crystal data |
Chemical formula | [CuBr(C6H7NO)2]Br·H2O |
Mr | 459.63 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 150 |
a, b, c (Å) | 7.9681 (6), 9.8543 (6), 11.1812 (8) |
α, β, γ (°) | 74.974 (6), 72.481 (6), 76.590 (6) |
V (Å3) | 797.24 (10) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 6.39 |
Crystal size (mm) | 0.3 × 0.2 × 0.2 |
|
Data collection |
Diffractometer | Agilent SuperNova (Dual, Cu at zero, Atlas) diffractometer |
Absorption correction | Multi-scan (CrysAlis PRO; Agilent, 2011) |
Tmin, Tmax | 0.073, 1.000 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 6592, 3668, 3086 |
Rint | 0.037 |
(sin θ/λ)max (Å−1) | 0.650 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.041, 0.092, 1.04 |
No. of reflections | 3668 |
No. of parameters | 197 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.92, −0.85 |
Selected geometric parameters (Å, º) topBr1—Cu1 | 2.4194 (6) | Cu1—O2B | 2.037 (3) |
Cu1—N11 | 1.983 (3) | Cu1—O2A | 2.247 (3) |
Cu1—N21 | 1.987 (3) | Cu1—Br1i | 3.2129 (6) |
| | | |
N11—Cu1—N21 | 168.98 (12) | O2B—Cu1—Br1 | 166.09 (9) |
N11—Cu1—O2B | 90.14 (11) | O2A—Cu1—Br1 | 100.21 (7) |
N21—Cu1—O2B | 81.45 (12) | N11—Cu1—Br1i | 99.40 (9) |
N11—Cu1—O2A | 77.10 (11) | N21—Cu1—Br1i | 86.10 (8) |
N21—Cu1—O2A | 96.24 (11) | O2B—Cu1—Br1i | 79.31 (9) |
O2B—Cu1—O2A | 93.69 (11) | O2A—Cu1—Br1i | 172.24 (8) |
N11—Cu1—Br1 | 92.47 (8) | Br1—Cu1—Br1i | 86.785 (17) |
N21—Cu1—Br1 | 97.41 (9) | | |
Symmetry code: (i) −x+1, −y, −z+1. |
Hydrogen-bond geometry (Å, º) top
D—H···A | D—H | H···A | D···A | D—H···A |
O2B—H2B···O1Wii | 0.71 (4) | 1.86 (4) | 2.573 (5) | 175 (5) |
O2A—H2A···Br2 | 0.78 (5) | 2.39 (5) | 3.163 (3) | 173 (4) |
O1W—H1W···Br2iii | 0.75 (5) | 2.60 (5) | 3.319 (4) | 162 (5) |
O1W—H2W···Br2 | 0.84 (6) | 2.44 (6) | 3.271 (3) | 169 (5) |
Symmetry codes: (ii) x−1, y, z; (iii) −x+2, −y+1, −z. |
Comparison of unit-cell parameters of (I) with those of the related compounds
(II), (III) and (IV) top | (I) | (II) | (III) | (IV) |
T (K) | 150 | 150 | 133 | 90 |
a (Å) | 7.9681 (6) | 7.71430 (10) | 7.9154 (6) | 7.9333 (3) |
b (Å) | 9.8543 (6) | 9.7359 (2) | 9.5718 (6) | 11.1019 (3) |
c (°) | 11.1812 (8) | 11.0072 (2) | 11.1614 (8) | 11.2436 (4) |
α (°) | 74.974 (6) | 74.570 (1) | 72.121 (3) | 102.670 (2) |
β (°) | 72.481 (6) | 72.311 (1) | 70.460 (3) | 102.670 (2) |
γ (°) | 76.590 (6) | 77.405 (1) | 76.231 (3) | 101.724 (1) |
V (Å3) | 797.24 (10) | 750.71 (2) | 749.77 (9) | 862.52 (5) |
Comparison of the coordination environment of the metal centre in (I) with
those reported for the related compounds (II), (III) and (IV) top | (I) | (II) | (III) | (IV) |
M—N (Å) | 1.984 (3) | 1.9883 (13) | 2.0988 (8) | 1.97282) |
| 1.987 (3) | 1.9858 (13) | 2.1004 (8) | 1.971 (2) |
M—O (Å) | 2.0384 (3) | 2.0382 (12) | 2.1209 (7) | 2.029 (2) |
| 2.2487 (3) | 2.2466 (4) | 2.1224 (8) | 2.179 (2) |
M—X (Å) | 2.4194 (2) | 2.2764 (4) | 2.4212 (3) | 2.2581 (2) |
| 3.2129 (6) | 3.0434 (5) | 2.4620 (3) | 3.475 (5) |
The preparation of coordination polymers remains an attractive field of research in coordination chemistry. We have been interested for some time in the use of simple pyridyl-substituted alcohols as organic linker ligands (Lah et al., 2006; Lah & Leban, 2010; Lapanje et al., 2012; Trdin & Lah, 2012). During the course of the preparation of new CuII complexes with 2-(pyridin-2-yl)methanol (2-pyMeOH) and various carboxylic acids, the reaction of CuBr2 was carried out in methanol. Surprisingly, the resulting product did not contain any of the itaconic acid species that was present in the reaction mixture. Crystal structure determination revealed the product to be the title ionic compound, [CuBr(2-pyMeOH)2]Br.H2O, (I) (Fig. 1).
The [CuBr(C6H7NO)2]+ cation of (I) shows a distorted square-pyramidal geometry, in which the CuII centre is coordinated by two neutral and crystallographically distinct 2-pyMeOH molecules in a bidentate chelating manner, and a Br atom as a terminal ligand. The basal plane consists of the CuN2OBr chromophore; the axial site is occupied by the remaining O atom of one of the two 2-pyMeOH ligands. The charge is balanced by a noncoordinating bromide anion. Some geometric parameters are listed in Table 1.
In addition, the structure contains solvent water molecules which are involved in the formation of infinite hydrogen-bonded chains oriented along the a axis (Fig. 2). Each water molecule is a hydrogen-bond donor to two neighbouring bromide anions and a hydrogen-bond acceptor from the hydroxy group of one of the two distinct 2-pyMeOH ligands. The remaining hydroxy group is involved in hydrogen-bond formation with the bromide counterion. Thus, each noncoordinating bromide anion acts as an acceptor of three hydrogen bonds (Table 2). The chains are held together by weak π–π stacking interactions (Fig. 3).
In a comparison of the structure of (I) with those of known ionic halide complexes of transition metals with simple pyridine alcohols, six structures need to be mentioned. Three CuII complexes are reported as mononuclear ionic compounds with the stoichiometry [CuXL2]X: X = Cl and L = 2-pyMeOH (Antonioli et al., 2007), X = Cl and L = 2-pyEtOH (Hamamci et al., 2004), and X = Br and L = 2-pyEtOH (Lah & Leban, 2010). All three crystallize as anhydrous compounds and contain cations with a similar arrangement of ligands around the CuII centre. Three further structures deserve a closer look: (a) a chloride complex with 2-pyMeOH, described as a dinuclear ionic complex with a formulation of [Cu2Cl2(2-pyMeOH)4]Cl2.2H2O, (II) (Lah & Leban, 2010); (b) an analogous cobalt complex, [Co2Cl2(2-pyMeOH)4]Cl2.2H2O, (III) (Yilmaz et al., 2004); and (c) a chloride complex of CuII and the 4-bromo derivative of 2-pyMeOH with a formulation of [CuCl(2-pyMeOH)2]Cl.H2O, (IV) (Hubrich et al., 2010).
These last three compounds are closely related to (I) so that their unit-cell parameters agree reasonably well [allowing for the additional Br atom on the 2-pyMeOH ligand in (IV)]. A comparison of the unit-cell parameters is listed in Table 3. Nevertheless, two of them are described as dinuclear [(II) and (III)], while (IV) is described as a mononuclear ionic compound.
Closer inspection of the coordination environment in all the reported structures reveals that the M—X distances (M = metal cation and X = halogenide anion) vary from structure to structure (Table 4). A strong coordinative bond of the second halogen atom is only observed in the case of (III), whereas in the other structures a significant difference in M—X distances for the `bonded' halogenide anions is observed. Considering the sum of the van der Waals radii for the present atoms (Standard reference?), there is an attractive interaction between the metal centre and the halogenido atom of the neighbouring unit in (II) and (III), and the description of (IV) as a mononuclear ionic compound is justified. Being aware that, in (I), the M—Br distance (3.2128 (6) Å) is just below the sum of the van der Waals radii (3.25 Å), the structure described here can also be described as a dinuclear ionic compound with the formulation [Cu2Br2(2-pyMeOH)4]Br2.2H2O (Fig. 4).