Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270104008030/fa1055sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270104008030/fa1055Isup2.hkl |
CCDC reference: 243582
The title compound was prepared by reaction of the corresponding aqua complex (Werner et al., 1983) with an excess of urea in an ethanol–water solution. Cu(sal-β-ala)(H2O) (10 mmol, 2.72 g) and urea (40 mmol, 2.4 g) were added to ethanol/water (120 ml; 3:1, v/v) and the mixture was heated to 333 K and stirred vigorously for 60 min until the solid phase disappeared. The solution was filtered and allowed to cool to room temperature. The resulting dark-blue well developed crystals were isolated and analyzed. Analysis (Carlo–Erba 1180 instrument) calculated for C11H15CuN3O5: C 39.70, H 4.54, N 12.63%; found: C 39.82, H 4.59, N 12.70%.
H atoms attached to C and N atoms were positioned geometrically, with N—H distances of 0.88 Å and C—H distances in the range 0.95–0.99 Å, and refiend as riding, with Uiso(H) values of 1.2Ueq(C,N). The parameters of H atoms attached to atom O1 were refined, with the O···H distances restrained to 0.95 (2) Å and with a free variable used for their common Uiso(H) value.
Data collection: CrysAlis CCD (Oxford Diffraction, 2002); cell refinement: CrysAlis RED (Oxford Diffraction, 2002); data reduction: CrysAlis RED; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEPIII (Johnson & Burnett, 1996); software used to prepare material for publication: SHELXL97 (Sheldrick, 1997) and PARST (Nardelli, 1995).
[Cu2(C10H9NO3)2(H2O)2]·2CH4N2O | Z = 1 |
Mr = 665.62 | F(000) = 342 |
Triclinic, P1 | Dx = 1.746 Mg m−3 |
a = 7.3218 (10) Å | Mo Kα radiation, λ = 0.71073 Å |
b = 9.0547 (14) Å | Cell parameters from 1272 reflections |
c = 10.7935 (15) Å | θ = 3.0–26.4° |
α = 105.638 (13)° | µ = 1.75 mm−1 |
β = 108.079 (12)° | T = 120 K |
γ = 98.697 (12)° | Needle, dark blue |
V = 633.14 (18) Å3 | 0.60 × 0.15 × 0.05 mm |
Kuma KM-4-Plus CCD diffractometer | 2210 independent reflections |
Radiation source: fine-focus sealed tube | 1941 reflections with I > 2σ(I) |
Enhance (Oxford Diffraction) monochromator | Rint = 0.036 |
Detector resolution: 16.3 pixels mm-1 | θmax = 25.0°, θmin = 3.9° |
ω scan | h = −7→8 |
Absorption correction: analytical CrysAlis RED (Oxford Diffraction, 2002) | k = −10→10 |
Tmin = 0.458, Tmax = 0.882 | l = −12→12 |
4325 measured reflections |
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)] = 0.032 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.085 | H-atom parameters constrained |
S = 1.01 | w = 1/[σ2(Fo2) + (0.0577P)2] where P = (Fo2 + 2Fc2)/3 |
2210 reflections | (Δ/σ)max < 0.001 |
181 parameters | Δρmax = 0.60 e Å−3 |
0 restraints | Δρmin = −0.46 e Å−3 |
[Cu2(C10H9NO3)2(H2O)2]·2CH4N2O | γ = 98.697 (12)° |
Mr = 665.62 | V = 633.14 (18) Å3 |
Triclinic, P1 | Z = 1 |
a = 7.3218 (10) Å | Mo Kα radiation |
b = 9.0547 (14) Å | µ = 1.75 mm−1 |
c = 10.7935 (15) Å | T = 120 K |
α = 105.638 (13)° | 0.60 × 0.15 × 0.05 mm |
β = 108.079 (12)° |
Kuma KM-4-Plus CCD diffractometer | 2210 independent reflections |
Absorption correction: analytical CrysAlis RED (Oxford Diffraction, 2002) | 1941 reflections with I > 2σ(I) |
Tmin = 0.458, Tmax = 0.882 | Rint = 0.036 |
4325 measured reflections |
R[F2 > 2σ(F2)] = 0.032 | 0 restraints |
wR(F2) = 0.085 | H-atom parameters constrained |
S = 1.01 | Δρmax = 0.60 e Å−3 |
2210 reflections | Δρmin = −0.46 e Å−3 |
181 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
Cu | 0.53149 (4) | 0.69727 (3) | 0.07211 (3) | 0.01315 (14) | |
O1 | 0.2898 (2) | 0.5182 (2) | 0.00128 (17) | 0.0131 (4) | |
H1V | 0.1761 | 0.5220 | −0.0631 | 0.016* | |
H1W | 0.2531 | 0.5040 | 0.0719 | 0.016* | |
O2 | 0.5760 (3) | 0.6614 (2) | 0.24738 (18) | 0.0158 (4) | |
O3 | 0.7636 (3) | 0.6449 (3) | 0.4452 (2) | 0.0271 (5) | |
O4 | 0.4524 (3) | 0.7080 (2) | −0.11013 (18) | 0.0155 (4) | |
N1 | 0.7516 (3) | 0.8858 (2) | 0.1500 (2) | 0.0142 (5) | |
C1 | 0.7449 (4) | 0.6912 (3) | 0.3453 (3) | 0.0156 (6) | |
C2 | 0.9230 (4) | 0.7899 (3) | 0.3364 (3) | 0.0162 (6) | |
H2A | 0.9650 | 0.7234 | 0.2665 | 0.019* | |
H2B | 1.0346 | 0.8264 | 0.4269 | 0.019* | |
C3 | 0.8776 (4) | 0.9338 (3) | 0.2969 (3) | 0.0161 (6) | |
H3A | 0.8091 | 0.9881 | 0.3543 | 0.019* | |
H3B | 1.0035 | 1.0096 | 0.3156 | 0.019* | |
C4 | 0.7886 (4) | 0.9779 (3) | 0.0833 (3) | 0.0164 (6) | |
H4 | 0.8936 | 1.0716 | 0.1346 | 0.020* | |
C5 | 0.6868 (4) | 0.9529 (3) | −0.0605 (3) | 0.0150 (6) | |
C6 | 0.5321 (4) | 0.8162 (3) | −0.1517 (3) | 0.0145 (5) | |
C7 | 0.4622 (4) | 0.7972 (3) | −0.2935 (3) | 0.0179 (6) | |
H7 | 0.3666 | 0.7024 | −0.3575 | 0.021* | |
C8 | 0.5288 (4) | 0.9126 (4) | −0.3423 (3) | 0.0217 (6) | |
H8 | 0.4788 | 0.8961 | −0.4387 | 0.026* | |
C9 | 0.6694 (4) | 1.0538 (4) | −0.2506 (3) | 0.0231 (6) | |
H9 | 0.7086 | 1.1361 | −0.2833 | 0.028* | |
C10 | 0.7499 (4) | 1.0716 (3) | −0.1128 (3) | 0.0196 (6) | |
H10 | 0.8499 | 1.1651 | −0.0510 | 0.024* | |
O12 | 0.0692 (3) | 0.4762 (2) | 0.15298 (19) | 0.0192 (4) | |
N13 | −0.0243 (3) | 0.3743 (3) | 0.2996 (2) | 0.0192 (5) | |
H13A | −0.1500 | 0.3465 | 0.2443 | 0.023* | |
H13B | 0.0096 | 0.3544 | 0.3779 | 0.023* | |
N14 | 0.3036 (3) | 0.4881 (3) | 0.3522 (2) | 0.0216 (5) | |
H14A | 0.3984 | 0.5368 | 0.3322 | 0.026* | |
H14B | 0.3331 | 0.4667 | 0.4298 | 0.026* | |
C11 | 0.1149 (4) | 0.4467 (3) | 0.2647 (3) | 0.0143 (5) |
U11 | U22 | U33 | U12 | U13 | U23 | |
Cu | 0.0121 (2) | 0.0134 (2) | 0.0123 (2) | 0.00116 (13) | 0.00253 (13) | 0.00526 (13) |
O1 | 0.0122 (9) | 0.0157 (9) | 0.0117 (9) | 0.0027 (7) | 0.0039 (7) | 0.0064 (7) |
O2 | 0.0123 (9) | 0.0197 (10) | 0.0148 (9) | 0.0022 (8) | 0.0035 (7) | 0.0075 (8) |
O3 | 0.0192 (10) | 0.0445 (13) | 0.0189 (11) | 0.0044 (10) | 0.0040 (8) | 0.0185 (10) |
O4 | 0.0148 (9) | 0.0158 (10) | 0.0149 (9) | 0.0015 (7) | 0.0034 (7) | 0.0075 (8) |
N1 | 0.0111 (11) | 0.0124 (11) | 0.0163 (11) | 0.0029 (9) | 0.0036 (9) | 0.0024 (9) |
C1 | 0.0155 (13) | 0.0168 (13) | 0.0129 (13) | 0.0041 (11) | 0.0043 (11) | 0.0036 (10) |
C2 | 0.0135 (13) | 0.0196 (14) | 0.0128 (13) | 0.0038 (11) | 0.0037 (11) | 0.0029 (11) |
C3 | 0.0128 (13) | 0.0144 (14) | 0.0160 (14) | 0.0009 (11) | 0.0033 (11) | 0.0012 (11) |
C4 | 0.0119 (13) | 0.0119 (13) | 0.0265 (15) | 0.0046 (10) | 0.0090 (11) | 0.0052 (11) |
C5 | 0.0140 (13) | 0.0158 (13) | 0.0227 (14) | 0.0093 (11) | 0.0109 (11) | 0.0101 (11) |
C6 | 0.0119 (13) | 0.0156 (13) | 0.0230 (14) | 0.0086 (11) | 0.0103 (11) | 0.0100 (11) |
C7 | 0.0149 (13) | 0.0211 (14) | 0.0232 (14) | 0.0080 (11) | 0.0093 (11) | 0.0117 (12) |
C8 | 0.0212 (14) | 0.0315 (16) | 0.0250 (15) | 0.0145 (13) | 0.0144 (12) | 0.0179 (13) |
C9 | 0.0215 (15) | 0.0287 (16) | 0.0367 (17) | 0.0132 (13) | 0.0192 (13) | 0.0244 (14) |
C10 | 0.0159 (13) | 0.0168 (14) | 0.0337 (17) | 0.0075 (11) | 0.0142 (12) | 0.0124 (12) |
O12 | 0.0125 (9) | 0.0307 (11) | 0.0166 (10) | 0.0046 (8) | 0.0040 (8) | 0.0139 (8) |
N13 | 0.0125 (11) | 0.0271 (13) | 0.0176 (12) | 0.0016 (10) | 0.0031 (9) | 0.0119 (10) |
N14 | 0.0121 (11) | 0.0334 (14) | 0.0188 (12) | 0.0018 (10) | 0.0021 (9) | 0.0146 (11) |
C11 | 0.0145 (13) | 0.0118 (13) | 0.0150 (13) | 0.0041 (10) | 0.0045 (10) | 0.0027 (10) |
Cu—O4 | 1.9046 (18) | C4—C5 | 1.435 (4) |
Cu—O2 | 1.9417 (18) | C4—H4 | 0.9500 |
Cu—N1 | 1.942 (2) | C5—C6 | 1.418 (4) |
Cu—O1 | 1.9922 (18) | C5—C10 | 1.423 (4) |
Cu—O1i | 2.5941 (18) | C6—C7 | 1.408 (4) |
Cu—Cui | 3.3847 (9) | C7—C8 | 1.381 (4) |
O1—Cui | 2.5941 (18) | C7—H7 | 0.9500 |
O1—H1V | 0.9161 | C8—C9 | 1.401 (4) |
O1—H1W | 0.9165 | C8—H8 | 0.9500 |
O2—C1 | 1.286 (3) | C9—C10 | 1.372 (4) |
O3—C1 | 1.236 (3) | C9—H9 | 0.9500 |
O4—C6 | 1.314 (3) | C10—H10 | 0.9500 |
N1—C4 | 1.289 (3) | O12—C11 | 1.260 (3) |
N1—C3 | 1.468 (3) | N13—C11 | 1.335 (4) |
C1—C2 | 1.510 (4) | N13—H13A | 0.8801 |
C2—C3 | 1.527 (4) | N13—H13B | 0.8796 |
C2—H2A | 0.9900 | N14—C11 | 1.336 (3) |
C2—H2B | 0.9900 | N14—H14A | 0.8801 |
C3—H3A | 0.9900 | N14—H14B | 0.8795 |
C3—H3B | 0.9900 | ||
O4—Cu—O2 | 171.49 (7) | N1—C3—H3A | 109.5 |
O4—Cu—N1 | 94.28 (8) | C2—C3—H3A | 109.5 |
O2—Cu—N1 | 94.14 (8) | N1—C3—H3B | 109.5 |
O4—Cu—O1 | 87.02 (7) | C2—C3—H3B | 109.5 |
O2—Cu—O1 | 84.48 (7) | H3A—C3—H3B | 108.1 |
N1—Cu—O1 | 173.92 (8) | N1—C4—C5 | 126.4 (3) |
O4—Cu—O1i | 89.27 (7) | N1—C4—H4 | 116.8 |
O2—Cu—O1i | 90.47 (7) | C5—C4—H4 | 116.8 |
N1—Cu—O1i | 100.16 (7) | C6—C5—C10 | 119.3 (2) |
O1—Cu—O1i | 85.79 (7) | C6—C5—C4 | 123.5 (2) |
O4—Cu—Cui | 87.69 (6) | C10—C5—C4 | 117.2 (2) |
O2—Cu—Cui | 87.11 (6) | O4—C6—C7 | 119.1 (2) |
N1—Cu—Cui | 136.09 (6) | O4—C6—C5 | 123.4 (2) |
O1—Cu—Cui | 49.85 (5) | C7—C6—C5 | 117.5 (2) |
O1i—Cu—Cui | 35.94 (4) | C8—C7—C6 | 121.8 (3) |
Cu—O1—Cui | 94.21 (7) | C8—C7—H7 | 119.1 |
Cu—O1—H1V | 118.8 | C6—C7—H7 | 119.1 |
Cui—O1—H1V | 118.6 | C7—C8—C9 | 120.5 (3) |
Cu—O1—H1W | 111.3 | C7—C8—H8 | 119.8 |
Cui—O1—H1W | 108.7 | C9—C8—H8 | 119.8 |
H1V—O1—H1W | 105.0 | C10—C9—C8 | 119.1 (3) |
C1—O2—Cu | 126.47 (17) | C10—C9—H9 | 120.5 |
C6—O4—Cu | 127.48 (16) | C8—C9—H9 | 120.5 |
C4—N1—C3 | 117.1 (2) | C9—C10—C5 | 121.4 (3) |
C4—N1—Cu | 124.39 (19) | C9—C10—H10 | 119.3 |
C3—N1—Cu | 118.39 (17) | C5—C10—H10 | 119.3 |
O3—C1—O2 | 122.4 (3) | C11—N13—H13A | 120.0 |
O3—C1—C2 | 120.2 (2) | C11—N13—H13B | 120.0 |
O2—C1—C2 | 117.4 (2) | H13A—N13—H13B | 120.0 |
C1—C2—C3 | 111.8 (2) | C11—N14—H14A | 120.0 |
C1—C2—H2A | 109.2 | C11—N14—H14B | 120.0 |
C3—C2—H2A | 109.2 | H14A—N14—H14B | 120.0 |
C1—C2—H2B | 109.2 | O12—C11—N13 | 120.9 (2) |
C3—C2—H2B | 109.2 | O12—C11—N14 | 121.1 (2) |
H2A—C2—H2B | 107.9 | N13—C11—N14 | 118.0 (2) |
N1—C3—C2 | 110.8 (2) | ||
O4—Cu—O1—Cui | 89.49 (7) | C4—N1—C3—C2 | −141.5 (2) |
N1—Cu—O2—C1 | −33.7 (2) | Cu—N1—C3—C2 | 42.4 (3) |
O1—Cu—O2—C1 | 152.2 (2) | C1—C2—C3—N1 | −73.8 (3) |
O1i—Cu—O2—C1 | 66.5 (2) | C3—N1—C4—C5 | 179.0 (2) |
Cui—Cu—O2—C1 | 102.3 (2) | Cu—N1—C4—C5 | −5.2 (4) |
N1—Cu—O4—C6 | −1.4 (2) | N1—C4—C5—C6 | −2.4 (4) |
O1—Cu—O4—C6 | 172.62 (19) | N1—C4—C5—C10 | 179.0 (2) |
O1i—Cu—O4—C6 | −101.55 (19) | Cu—O4—C6—C7 | 175.13 (17) |
Cui—Cu—O4—C6 | −137.48 (19) | Cu—O4—C6—C5 | −4.8 (3) |
O4—Cu—N1—C4 | 6.3 (2) | C10—C5—C6—O4 | −173.6 (2) |
O2—Cu—N1—C4 | −172.5 (2) | C4—C5—C6—O4 | 7.8 (4) |
O1i—Cu—N1—C4 | 96.3 (2) | C10—C5—C6—C7 | 6.4 (4) |
Cui—Cu—N1—C4 | 97.4 (2) | C4—C5—C6—C7 | −172.1 (2) |
O4—Cu—N1—C3 | −177.99 (17) | O4—C6—C7—C8 | 174.8 (2) |
O2—Cu—N1—C3 | 3.26 (18) | C5—C6—C7—C8 | −5.2 (4) |
O1i—Cu—N1—C3 | −87.96 (18) | C6—C7—C8—C9 | −0.1 (4) |
Cui—Cu—N1—C3 | −86.88 (19) | C7—C8—C9—C10 | 4.2 (4) |
Cu—O2—C1—O3 | −169.6 (2) | C8—C9—C10—C5 | −2.9 (4) |
Cu—O2—C1—C2 | 11.8 (3) | C6—C5—C10—C9 | −2.5 (4) |
O3—C1—C2—C3 | −133.6 (3) | C4—C5—C10—C9 | 176.2 (3) |
O2—C1—C2—C3 | 45.0 (3) |
Symmetry code: (i) −x+1, −y+1, −z. |
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1V···O12ii | 0.92 | 1.76 | 2.656 (2) | 165 |
O1—H1W···O12 | 0.92 | 1.84 | 2.688 (3) | 153 |
N13—H13A···O4ii | 0.88 | 2.13 | 3.009 (3) | 177 |
N13—H13B···O3iii | 0.88 | 2.10 | 2.891 (3) | 149 |
N14—H14A···O2 | 0.88 | 2.16 | 3.022 (3) | 167 |
N14—H14B···O3iii | 0.88 | 2.11 | 2.895 (3) | 148 |
Symmetry codes: (ii) −x, −y+1, −z; (iii) −x+1, −y+1, −z+1. |
Experimental details
Crystal data | |
Chemical formula | [Cu2(C10H9NO3)2(H2O)2]·2CH4N2O |
Mr | 665.62 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 120 |
a, b, c (Å) | 7.3218 (10), 9.0547 (14), 10.7935 (15) |
α, β, γ (°) | 105.638 (13), 108.079 (12), 98.697 (12) |
V (Å3) | 633.14 (18) |
Z | 1 |
Radiation type | Mo Kα |
µ (mm−1) | 1.75 |
Crystal size (mm) | 0.60 × 0.15 × 0.05 |
Data collection | |
Diffractometer | Kuma KM-4-Plus CCD diffractometer |
Absorption correction | Analytical CrysAlis RED (Oxford Diffraction, 2002) |
Tmin, Tmax | 0.458, 0.882 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 4325, 2210, 1941 |
Rint | 0.036 |
(sin θ/λ)max (Å−1) | 0.595 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.032, 0.085, 1.01 |
No. of reflections | 2210 |
No. of parameters | 181 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.60, −0.46 |
Computer programs: CrysAlis CCD (Oxford Diffraction, 2002), CrysAlis RED (Oxford Diffraction, 2002), CrysAlis RED, SHELXS97 (Sheldrick, 1990), ORTEPIII (Johnson & Burnett, 1996), SHELXL97 (Sheldrick, 1997) and PARST (Nardelli, 1995).
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1V···O12i | 0.92 | 1.76 | 2.656 (2) | 165 |
O1—H1W···O12 | 0.92 | 1.84 | 2.688 (3) | 153 |
N13—H13A···O4i | 0.88 | 2.13 | 3.009 (3) | 177 |
N13—H13B···O3ii | 0.88 | 2.10 | 2.891 (3) | 149 |
N14—H14A···O2 | 0.88 | 2.16 | 3.022 (3) | 167 |
N14—H14B···O3ii | 0.88 | 2.11 | 2.895 (3) | 148 |
Symmetry codes: (i) −x, −y+1, −z; (ii) −x+1, −y+1, −z+1. |
CuII centers coordinated by O,N,O' three-donor Schiff base dianions (TSB) derived from salicylaldehyde and amino acids can form a variety of chelates by filling out the coordination environment, esulting in a square-planar (Warda et al., 1997; Warda, 1997a), square-pyramidal (Hill et al., 1999; Kettmann et al., 1993; Butcher et al., 2003; Weng et al., 2002; Vančo et al., 2003) or distorted square-bipyramidal polyhedron (Marek et al., 2003), or in a mixed square-pyramidal/square-planar form (Werner et al., 1983). Depending on the proportions and physico-chemical properties of the additional ligands, monomeric (Warda, 1997a,b; Warda, 1998a), dimeric (Werner et al., 1983; Warda, 1998c; Hill et al., 1999; Vančo et al., 2003), oligomeric (Warda, 1997c) or polymeric (Warda et al., 1997; Warda, 1998 d; Kettmann et al., 1993) crystal structures are formed. One of the features specific to the Cu(TSB) complexes is stabilization of the oxidation number of CuII, as could be demonstrated in the case of thiourea Cu(TSB) complexes (Pavelčík et al., 1981; Warda et al., 1998; Švajlenová et al., 1978), or the cuprates with thiocyanate ions in the inner coordination sphere of CuII atom (Vančo et al., 2003; Marek et al., 2003; Kettmann et al., 1992; Sivý et al., 1990).
The unique distorted square-pyramidal arrangement of CuII also gives the Cu(TSB) complexes the potential to act as antiradical (Bergendi et al., 1991; Valentová et al., 1995a), radioprotective (Valentová et al., 1995b) and antimicrobial agents (Sokolík et al., 1997), or as inhibitors of enzymatic systems (Kráľová, et al., 2004). In the present and in recent studies, the greatest emphasis was given to the Schiff base chelates with additional molecular N-ligands, mostly derived from pyridine, imidazole, pyrazole or quinoline. Only a few papers have dealt with the structural characterization or biological activity of urea complexes, where urea usually acts as an O-ligand (Warda et al., 1998; Valent et al., 2002). These studies introduced the structures of urea-(N-salicylideneglycinato)copper(II) and urea-(N-salicylidenemethylalaninato)copper(II), and the antimicrobial potential of the former was mentioned. From the structural point of view, the urea ligand offers the possibility of forming an extensive hydrogen-bonding network through the involvement of two non-coordinated NH2 groups. In light of the biological activities mentioned above and their relationship to structural properties, the title compound, (I), was synthesized and studied.
The dimer of (I) consists of two [Cu(sal-β-ala)(H2O)] coordination units spanning a crystallographic inversion center (Fig. 1). The unique CuII atom adopts a (4 + 1)-square-pyramidal geometry, formed by a tridentate O,N,O'-N-salicylidene-β-alaninate dianion and the water O atom in the basal plane (selected geometric parameters are given in Table 1). The apical position is occupied by the water Oi atom from the second unit [symmetry code: (i) 1 − x, 1 − y, −z]. The resulting [Cu(sal-β-ala)(H2O)]2 dimer containing two bridging µ-aqua molecules fixed in their positions by a grid of hydrogen bonds is a structutal motive observed for the first time in N-salicylideneamino acid copper(II) complexes. The structure of dimer (I) thus differs significantly from the structure of the starting material [Cu2(sal-β-ala)2(H2O)]·H2O, (II) (Werner et al., 1983), where the dimer is formed by two coordination units connected via two Cu—O bonds with bridging phenolate O atoms of the adjacent unit at distances 1.986 and 2.013 Å, respectively. In addition, the CuII coordination polyhedra in (I) and (II) are different. The polyhedra of the two CuII atoms in (II) have distorted square-planar and square-pyramidal configurations, with the apical position occupied by the water molecule and a Cu—O distance of 2.295 Å, while the coordination polyhedra of both the central atoms in (I) are uniformly square-pyramidal. The equatorial Cu—O1(water) bond distance in the basal plane of the pyramid in (I) decreased to 1.9927 (18) Å and the apical Cu–O1i bond distance increased to 2.5946 (18) Å, resembling a Jahn–Teller effect. The Cu–water lengths are comparable to the average lengths (1.95 Å and 2.43 Å) of these bonds in related Cu complexes reported in the Cambridge Structural Database (Version 5.24.3; Allen, 2002).
The pyramidal basal plane is nearly planar; only the Cu atom and two opposite O atoms (O2 and O4) are shifted slightly from the mean plane through the four basal atoms (all deviations are in the range 0.04–0.05 Å) in one direction, and the remaining two basal atoms are shifted in the opposite direction. In addition, the phenyl (labeled A in the chemical diagram) and the first six-membered metallochelate ring (labeled B) of the (sal-β-ala) moiety are nearly planar (the mean deviation of contributing atoms from the least-squares planes are 0.022 and 0.033 Å, respectively), while the second six-membered chelate ring (ring C) is significantly deformed; atoms C1 and C2 are displaced by 0.548 (3) and 1.049 (3) Å from the mean plane through the remaining four atoms (the mean deviation from the plane is 0.016 Å). The Cremer & Pople (1975) puckering parameters for ring C are Q = 0.668 (2) Å, Θ = −154.4 (4)°, ϕ2 =78.7 (2)°. The angle between the planes of rings A and B, and the angle between the plane of ring B and the planar part of ring C, are 6.45 (7) and 3.04 (5)°, respectively.
In the extended structure of (I), the complex dimers and molecules of urea are linked by a network of hydrogen bonds (Table 2 and Fig. 2) into a two-dimensional grid of molecules parallel to [101]. The two shortest hydrogen bonds [O···O = 2.687 (3) and 2.656 (2) Å] connect the O atom of urea and the two µ-aqua ligands of two adjacent complexes. The hydrogen bond involving the N14/H14A unit as donor is bifurcated.
The chelate ring system resulting from the Schiff base ligand coordination is a suitable electronic system for metaloaromaticity (Masui, 2001) and related interactions. Crystals of (I) exhibit the superposition of pyramidal base planes, with possible π–π interactions in the [100] direction.