metal-organic compounds
Bis{2-[(5-hydroxypentyl)iminomethyl]phenolato-κ2N,O1}copper(II)
aDepartment of Chemistry, University of Calcutta, 92 A.P.C. Road, Kolkata 700 009, USA
*Correspondence e-mail: sgchem@caluniv.ac.in
In the title compound, [Cu(C12H16NO2)2], the CuII ion, located on a center of inversion, is coordinated by two singly deprotonated Schiff base ligands derived from condensation of salicyldehyde and 1-aminopentan-5-ol. The imino N and phenol O atoms from both ligands offer a square-planar arrangement around the metal ion. The Cu—N and Cu—O bond lengths are 2.0146 (15) and 1.8870 (12) Å, respectively. Since the Cu—O and Cu—N bond lengths are different, it can be concluded that the resulting geometry of the complex is distorted. The aliphatic –OH group of the ligand is not coordinated and points away from the metal coordination zone and actively participates in hydrogen bonding connecting two other units and thus stabilizing the This results in a two-dimensional extended array parallel to (201).
Related literature
For the participation of the copper ion in the active sites of a large number of metalloproteins involved in important biological electron-transfer reactions, see: Reedijk & Bouwman (1999); Solomon et al. (2001); Hatcher & Karlin (2004); Kaim & Rall (1996). For references regarding the t4 value, see: Yang et al. (2007). For similar Cu—N and Cu—O bond lengths, see: Maeda et al. (2003); Akimova et al. (2001); Pawlicki et al. (2007); Verma et al. (2011); Khandar & Nejati (2000); Sundaravel et al. (2009).
Experimental
Crystal data
|
|
Data collection: APEX2 (Bruker, 2004); cell SAINT (Bruker, 2004); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: Mercury (Macrae et al., 2008).
Supporting information
https://doi.org/10.1107/S1600536813016802/bv2221sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536813016802/bv2221Isup2.hkl
The solution of 5-amino-1-pentanol (3 mmol, 650.8 mg) in methanol (20 mL) was added to the solution of salicylaldehyde (3 mmol, 366.36 mg) in methanol (20 ml) under vigorous stirring condition. The resulting reaction mixture was subsequently refluxed with stirring for 4 h. Completion of the reaction checked by thin layer
(TLC). After reaction was complete, the solution was dried over Na2SO4, followed by filtration and the solvent was removed under reduced pressure to get the ligand. Now a solution of Cu(OAc)2.H2O (1.5 mmol, 299.47 mg) in methanol (20 ml) was added to the solution of the prepared crude ligand (3 mmol, 621.84 mg) in methanol(20 ml) with constant stirring. The resulting mixture was stirred for 3 h at room temperature and then filtered. The resulting dark brown solution on slow evaporation gave a brown amorphous solid which was washed with diethyl ether properly and dried in vacuum desiccator containing anhydrous CaCl2. X-ray quality single crystals were grown from acetonitrile by the slow evaporation method.The H atoms were placed in calculated positions and refined as riding atoms, with C—H = 0.93 Å, aliphatic C – H = 0.97 Å and O – H = 0.82 Å.
Coordination chemistry of copper complexes of chelating ligands is a subject of continuing importance in connection with their structural, spectral, and redox properties in general and from the standpoint of their relevance to copper-containing metalloproteins in particular (Solomon et al., 2001; Hatcher & Karlin, 2004; Kaim & Rall, 1996). Copper ions are found in the active sites of a large number of metalloproteins involved in important biological electron-transfer reactions, as well as in redox processes of molecular oxygen (Reedijk & Bouwman, 1999).
Crystallographic analysis reveals that the τ4 value of 0 (α = O2 - Cu1 - O2_a = 180.00 and β = N1 - Cu1 - N1_a = 180.00) as a consequence of the Cu lying on a center of inversion thus supporting an assignment of distorted square planar geometry around the central metal ion (Yang et al. 2007). The complex exhibits a Cu1 – N1 bond length of 2.0146 (16) Å. In a perfectly square planar CuN4 moiety, the average CuII – N distance lies in the range of 1.980 (9) and 2.018 (9) Å (Maeda et al.,2003, Akimova et al., 2001). The Cu – N bond length value is comparable to the previously reported nearly planar CuII (2.020 Å, 2.065 Å, 1.977 Å) (Pawlicki et al. 2007). It agrees well with the CuN2O2 monomer (τ4 = 1/5) having average CuII – N bond length range of 2.071 Å (Verma et al., 2011). The Cu1 – O2 bond distance in the complex is 1.8871 (11) Å. It is well established in the literature that in a nearly square planar geometry, the CuII – phenolic oxygen bond length lies in the range of 1.84 Å to 1.93 Å (Khandar & Nejati, 2000; Sundaravel et al., 2009). Since the Cu - O and Cu - N bond lengths are different, therefore, it can be concluded that the resultant geometry is a distorted square planar one. The pendant –OH group actively participates in H-bonding and connects two other units stabilizing the As a result we have a two-dimensional extended array parallel to 201 plane with O1 - H1 - - - O1 length 2.864 (2) Å.
of the title mononuclear complex consists of one CuII ion, which is located on a center of inversion, and two singly deprotonated ligands, HL-, with the phenolic O atom being deprotonated. The phenolic O atoms (O2 and O2_a; symmetry code: (a) 2-x, 1-y, 1-z) and the imine N atoms (N1 and N1_a; symmetry code: (a) 2-x, 1-y, 1-z) from both the ligands coordinate to the same CuII center in the trans disposition to each other. The aliphatic –OH group remains as a pendant arm and is pointing away from the metal coordination zone. This uncoordinated oxygen atom, O1, is 8.083 Å away from the CuII ion. The complex has aFor the participation of the copper ion in the active sites of a large number of metalloproteins involved in important biological electron-transfer reactions, see: Reedijk & Bouwman (1999); Solomon et al. (2001); Hatcher & Karlin (2004); Kaim & Rall (1996). For references regarding the t4 value, see: Yang et al. (2007). For similar Cu—N and Cu—O bond lengths, see: Maeda et al. (2003); Akimova et al. (2001); Pawlicki et al. (2007); Verma et al. (2011); Khandar & Nejati (2000); Sundaravel et al. (2009).
Data collection: APEX2 (Bruker, 2004); cell
SAINT (Bruker, 2004); data reduction: SAINT (Bruker, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: Mercury (Macrae et al., 2008).[Cu(C12H16NO2)2] | F(000) = 502.0 |
Mr = 476.07 | Dx = 1.385 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 13343 reflections |
a = 11.8815 (8) Å | θ = 1.8–27.5° |
b = 5.2219 (3) Å | µ = 0.99 mm−1 |
c = 18.9588 (12) Å | T = 296 K |
β = 102.876 (2)° | Block, dark green |
V = 1146.70 (12) Å3 | 0.8 × 0.6 × 0.4 mm |
Z = 2 |
Bruker APEXII SMART CCD diffractometer | 2549 independent reflections |
Radiation source: fine-focus sealed tube | 2174 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.027 |
φ and ω scans | θmax = 27.5°, θmin = 1.8° |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | h = −14→14 |
Tmin = 0.497, Tmax = 0.674 | k = −6→6 |
13343 measured reflections | l = −24→24 |
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)] = 0.030 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.096 | H-atom parameters constrained |
S = 0.95 | w = 1/[σ2(Fo2) + (0.0695P)2 + 0.3017P] where P = (Fo2 + 2Fc2)/3 |
2549 reflections | (Δ/σ)max = 0.015 |
143 parameters | Δρmax = 0.27 e Å−3 |
0 restraints | Δρmin = −0.30 e Å−3 |
[Cu(C12H16NO2)2] | V = 1146.70 (12) Å3 |
Mr = 476.07 | Z = 2 |
Monoclinic, P21/c | Mo Kα radiation |
a = 11.8815 (8) Å | µ = 0.99 mm−1 |
b = 5.2219 (3) Å | T = 296 K |
c = 18.9588 (12) Å | 0.8 × 0.6 × 0.4 mm |
β = 102.876 (2)° |
Bruker APEXII SMART CCD diffractometer | 2549 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 2174 reflections with I > 2σ(I) |
Tmin = 0.497, Tmax = 0.674 | Rint = 0.027 |
13343 measured reflections |
R[F2 > 2σ(F2)] = 0.030 | 0 restraints |
wR(F2) = 0.096 | H-atom parameters constrained |
S = 0.95 | Δρmax = 0.27 e Å−3 |
2549 reflections | Δρmin = −0.30 e Å−3 |
143 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 | ||
Cu1 | 1.0000 | 0.5000 | 0.5000 | 0.03217 (12) | |
O1 | 0.50800 (15) | 0.8210 (3) | 0.72046 (8) | 0.0640 (4) | |
H1 | 0.4971 | 0.9476 | 0.7436 | 0.096* | |
O2 | 1.04519 (10) | 0.2230 (2) | 0.44865 (7) | 0.0440 (3) | |
N1 | 0.83417 (13) | 0.4686 (3) | 0.44597 (8) | 0.0338 (3) | |
C1 | 0.74512 (14) | 0.6417 (3) | 0.46237 (9) | 0.0372 (4) | |
H1A | 0.6794 | 0.6453 | 0.4215 | 0.045* | |
H1B | 0.7761 | 0.8140 | 0.4697 | 0.045* | |
C2 | 0.70561 (16) | 0.5564 (3) | 0.52942 (10) | 0.0389 (4) | |
H2A | 0.6628 | 0.3975 | 0.5191 | 0.047* | |
H2B | 0.7727 | 0.5236 | 0.5680 | 0.047* | |
C3 | 0.63016 (16) | 0.7546 (4) | 0.55460 (10) | 0.0420 (4) | |
H3A | 0.5621 | 0.7829 | 0.5163 | 0.050* | |
H3B | 0.6722 | 0.9150 | 0.5629 | 0.050* | |
C4 | 0.59209 (16) | 0.6804 (4) | 0.62336 (10) | 0.0422 (4) | |
H4A | 0.5346 | 0.5457 | 0.6122 | 0.051* | |
H4B | 0.6579 | 0.6127 | 0.6581 | 0.051* | |
C5 | 0.5428 (2) | 0.8995 (5) | 0.65661 (12) | 0.0571 (5) | |
H5A | 0.6001 | 1.0342 | 0.6685 | 0.068* | |
H5B | 0.4768 | 0.9679 | 0.6222 | 0.068* | |
C6 | 0.79987 (14) | 0.3133 (3) | 0.39297 (9) | 0.0375 (4) | |
H6 | 0.7230 | 0.3277 | 0.3687 | 0.045* | |
C7 | 0.86641 (14) | 0.1202 (3) | 0.36685 (8) | 0.0362 (4) | |
C8 | 0.98489 (15) | 0.0831 (3) | 0.39729 (9) | 0.0357 (3) | |
C9 | 1.04061 (17) | −0.1203 (3) | 0.36855 (10) | 0.0437 (4) | |
H9 | 1.1187 | −0.1500 | 0.3873 | 0.052* | |
C10 | 0.98222 (18) | −0.2730 (4) | 0.31404 (10) | 0.0485 (5) | |
H10 | 1.0212 | −0.4049 | 0.2967 | 0.058* | |
C11 | 0.86595 (19) | −0.2348 (4) | 0.28419 (10) | 0.0502 (5) | |
H11 | 0.8270 | −0.3392 | 0.2469 | 0.060* | |
C12 | 0.80936 (19) | −0.0411 (4) | 0.31035 (11) | 0.0452 (4) | |
H12 | 0.7313 | −0.0149 | 0.2904 | 0.054* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Cu1 | 0.02804 (18) | 0.03330 (18) | 0.03728 (18) | 0.00376 (10) | 0.01180 (12) | −0.00224 (10) |
O1 | 0.0847 (11) | 0.0657 (9) | 0.0553 (8) | 0.0084 (8) | 0.0448 (8) | 0.0046 (7) |
O2 | 0.0337 (6) | 0.0444 (7) | 0.0535 (7) | 0.0065 (5) | 0.0088 (5) | −0.0123 (6) |
N1 | 0.0299 (7) | 0.0393 (8) | 0.0358 (7) | 0.0058 (5) | 0.0146 (6) | 0.0026 (5) |
C1 | 0.0309 (8) | 0.0425 (9) | 0.0405 (8) | 0.0106 (7) | 0.0131 (6) | 0.0037 (7) |
C2 | 0.0356 (9) | 0.0362 (8) | 0.0498 (10) | 0.0068 (7) | 0.0203 (7) | 0.0052 (7) |
C3 | 0.0427 (9) | 0.0422 (9) | 0.0471 (9) | 0.0112 (7) | 0.0226 (8) | 0.0079 (7) |
C4 | 0.0442 (10) | 0.0426 (9) | 0.0444 (9) | 0.0038 (7) | 0.0198 (7) | 0.0042 (7) |
C5 | 0.0746 (15) | 0.0529 (12) | 0.0562 (12) | 0.0147 (11) | 0.0415 (11) | 0.0116 (10) |
C6 | 0.0312 (8) | 0.0467 (9) | 0.0359 (8) | 0.0016 (7) | 0.0103 (6) | 0.0029 (7) |
C7 | 0.0402 (9) | 0.0369 (9) | 0.0350 (8) | −0.0010 (7) | 0.0158 (7) | 0.0006 (7) |
C8 | 0.0400 (9) | 0.0318 (8) | 0.0386 (8) | 0.0028 (7) | 0.0161 (7) | 0.0015 (7) |
C9 | 0.0481 (10) | 0.0371 (9) | 0.0486 (10) | 0.0099 (8) | 0.0167 (8) | −0.0001 (8) |
C10 | 0.0693 (13) | 0.0356 (9) | 0.0464 (10) | 0.0071 (9) | 0.0252 (9) | −0.0032 (8) |
C11 | 0.0651 (13) | 0.0474 (10) | 0.0399 (9) | −0.0069 (9) | 0.0156 (8) | −0.0066 (8) |
C12 | 0.0459 (11) | 0.0537 (11) | 0.0369 (9) | −0.0038 (8) | 0.0110 (8) | −0.0025 (7) |
Cu1—O2i | 1.8870 (12) | C4—C5 | 1.488 (3) |
Cu1—O2 | 1.8870 (12) | C4—H4A | 0.9700 |
Cu1—N1i | 2.0146 (15) | C4—H4B | 0.9700 |
Cu1—N1 | 2.0146 (15) | C5—H5A | 0.9700 |
O1—C5 | 1.424 (2) | C5—H5B | 0.9700 |
O1—H1 | 0.8200 | C6—C7 | 1.436 (2) |
O2—C8 | 1.298 (2) | C6—H6 | 0.9300 |
N1—C6 | 1.285 (2) | C7—C8 | 1.411 (2) |
N1—C1 | 1.476 (2) | C7—C12 | 1.411 (3) |
C1—C2 | 1.517 (2) | C8—C9 | 1.423 (2) |
C1—H1A | 0.9700 | C9—C10 | 1.366 (3) |
C1—H1B | 0.9700 | C9—H9 | 0.9300 |
C2—C3 | 1.514 (2) | C10—C11 | 1.386 (3) |
C2—H2A | 0.9700 | C10—H10 | 0.9300 |
C2—H2B | 0.9700 | C11—C12 | 1.368 (3) |
C3—C4 | 1.522 (2) | C11—H11 | 0.9300 |
C3—H3A | 0.9700 | C12—H12 | 0.9300 |
C3—H3B | 0.9700 | ||
O2i—Cu1—O2 | 179.999 (1) | C3—C4—H4A | 109.0 |
O2i—Cu1—N1i | 91.94 (5) | C5—C4—H4B | 109.0 |
O2—Cu1—N1i | 88.06 (5) | C3—C4—H4B | 109.0 |
O2i—Cu1—N1 | 88.06 (5) | H4A—C4—H4B | 107.8 |
O2—Cu1—N1 | 91.94 (5) | O1—C5—C4 | 110.77 (17) |
N1i—Cu1—N1 | 179.998 (1) | O1—C5—H5A | 109.5 |
C5—O1—H1 | 109.5 | C4—C5—H5A | 109.5 |
C8—O2—Cu1 | 130.21 (11) | O1—C5—H5B | 109.5 |
C6—N1—C1 | 115.71 (15) | C4—C5—H5B | 109.5 |
C6—N1—Cu1 | 123.56 (12) | H5A—C5—H5B | 108.1 |
C1—N1—Cu1 | 120.58 (11) | N1—C6—C7 | 127.59 (15) |
N1—C1—C2 | 111.53 (13) | N1—C6—H6 | 116.2 |
N1—C1—H1A | 109.3 | C7—C6—H6 | 116.2 |
C2—C1—H1A | 109.3 | C8—C7—C12 | 119.69 (16) |
N1—C1—H1B | 109.3 | C8—C7—C6 | 122.08 (15) |
C2—C1—H1B | 109.3 | C12—C7—C6 | 118.20 (16) |
H1A—C1—H1B | 108.0 | O2—C8—C7 | 124.29 (15) |
C3—C2—C1 | 112.27 (14) | O2—C8—C9 | 118.78 (16) |
C3—C2—H2A | 109.2 | C7—C8—C9 | 116.92 (16) |
C1—C2—H2A | 109.2 | C10—C9—C8 | 121.64 (18) |
C3—C2—H2B | 109.2 | C10—C9—H9 | 119.2 |
C1—C2—H2B | 109.2 | C8—C9—H9 | 119.2 |
H2A—C2—H2B | 107.9 | C9—C10—C11 | 121.12 (17) |
C2—C3—C4 | 113.92 (15) | C9—C10—H10 | 119.4 |
C2—C3—H3A | 108.8 | C11—C10—H10 | 119.4 |
C4—C3—H3A | 108.8 | C12—C11—C10 | 118.98 (18) |
C2—C3—H3B | 108.8 | C12—C11—H11 | 120.5 |
C4—C3—H3B | 108.8 | C10—C11—H11 | 120.5 |
H3A—C3—H3B | 107.7 | C11—C12—C7 | 121.66 (19) |
C5—C4—C3 | 112.76 (15) | C11—C12—H12 | 119.2 |
C5—C4—H4A | 109.0 | C7—C12—H12 | 119.2 |
Symmetry code: (i) −x+2, −y+1, −z+1. |
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···O1ii | 0.82 | 2.07 | 2.864 (2) | 163 |
C1—H1B···O2i | 0.97 | 2.34 | 2.771 (2) | 106 |
Symmetry codes: (i) −x+2, −y+1, −z+1; (ii) −x+1, y+1/2, −z+3/2. |
Experimental details
Crystal data | |
Chemical formula | [Cu(C12H16NO2)2] |
Mr | 476.07 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 296 |
a, b, c (Å) | 11.8815 (8), 5.2219 (3), 18.9588 (12) |
β (°) | 102.876 (2) |
V (Å3) | 1146.70 (12) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.99 |
Crystal size (mm) | 0.8 × 0.6 × 0.4 |
Data collection | |
Diffractometer | Bruker APEXII SMART CCD |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.497, 0.674 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 13343, 2549, 2174 |
Rint | 0.027 |
(sin θ/λ)max (Å−1) | 0.650 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.030, 0.096, 0.95 |
No. of reflections | 2549 |
No. of parameters | 143 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.27, −0.30 |
Computer programs: APEX2 (Bruker, 2004), SAINT (Bruker, 2004), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), ORTEP-3 for Windows (Farrugia, 2012), Mercury (Macrae et al., 2008).
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1···O1i | 0.8200 | 2.0700 | 2.864 (2) | 163.00 |
C1—H1B···O2ii | 0.9700 | 2.3400 | 2.771 (2) | 106.00 |
Symmetry codes: (i) −x+1, y+1/2, −z+3/2; (ii) −x+2, −y+1, −z+1. |
Acknowledgements
Financial support from the University Grants Commission for a junior research fellowship to SM [Sanction No. UGC/749/Jr. Fellow(Sc.)] and an RFSMS fellowship (Sanction No. UGC/740/RFSMS) to RM is gratefully acknowledged. We thank the DST for a junior research fellowship to YS (Sanction No. SERB/F/1585/2012–13). DST–FIST is acknowledged for providing the X-ray diffraction facility at the Department of Chemistry, University of Calcutta.
References
Akimova, E. V. R., Nazarenko, A. Y., Chen, L., Krieger, P. W., Herrera, A. M., Tarasov, V. V. & Robinson, P. D. (2001). Inorg. Chim. Acta, 324, 1–15. Google Scholar
Bruker (2004). APEX2 and SAINT. Bruker–Nonius AXS Inc., Madison, Wisconsin, USA. Google Scholar
Farrugia, L. J. (2012). J. Appl. Cryst. 45, 849–854. Web of Science CrossRef CAS IUCr Journals Google Scholar
Hatcher, L. Q. & Karlin, K. D. (2004). J. Biol. Inorg. Chem. 9, 669–683. Web of Science CrossRef PubMed CAS Google Scholar
Kaim, W. & Rall, J. (1996). Angew. Chem. Int. Ed. 35, 43–60. CrossRef CAS Google Scholar
Khandar, A. A. & Nejati, M. (2000). Polyhedron, 19, 607–613. Web of Science CSD CrossRef CAS Google Scholar
Macrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe, P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. & Wood, P. A. (2008). J. Appl. Cryst. 41, 466–470. Web of Science CSD CrossRef CAS IUCr Journals Google Scholar
Maeda, H., Osuka, A., Ishikawa, Y., Aritome, I., Hisaeda, Y. & Furuta, H. (2003). Org. Lett. 5, 1293–1296. Web of Science CSD CrossRef PubMed CAS Google Scholar
Pawlicki, M., Kanska, I. & Latos-Grazynski, L. (2007). Inorg. Chem. 46, 6575–6584. Web of Science CSD CrossRef PubMed CAS Google Scholar
Reedijk, J. & Bouwman, E. (1999). In Bioinorganic Catalysis, 2nd ed. New York: Marcel Dekker. Google Scholar
Sheldrick, G. M. (1996). SADABS. University of Göttingen, Germany. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
Solomon, E. I., Chen, P., Metz, M., Lee, S.-K. & Palmer, A. E. (2001). Angew. Chem. Int. Ed. 40, 4570–4590. CrossRef CAS Google Scholar
Sundaravel, K., Suresh, E. & Palaniandavar, M. (2009). Inorg. Chim. Acta, 362, 199–207. Web of Science CSD CrossRef CAS Google Scholar
Verma, P., Weir, J., Mirica, L., Stack, T. & Daniel, P. (2011). Inorg. Chem. 50, 9816–9825. Web of Science CSD CrossRef CAS PubMed Google Scholar
Yang, L., Powell, D. R. & Houser, R. P. (2007). Dalton Trans. pp. 955–964. Web of Science CSD CrossRef PubMed CAS Google Scholar
This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
Coordination chemistry of copper complexes of chelating ligands is a subject of continuing importance in connection with their structural, spectral, and redox properties in general and from the standpoint of their relevance to copper-containing metalloproteins in particular (Solomon et al., 2001; Hatcher & Karlin, 2004; Kaim & Rall, 1996). Copper ions are found in the active sites of a large number of metalloproteins involved in important biological electron-transfer reactions, as well as in redox processes of molecular oxygen (Reedijk & Bouwman, 1999).
Crystallographic analysis reveals that the asymmetric unit of the title mononuclear complex consists of one CuII ion, which is located on a center of inversion, and two singly deprotonated ligands, HL-, with the phenolic O atom being deprotonated. The phenolic O atoms (O2 and O2_a; symmetry code: (a) 2-x, 1-y, 1-z) and the imine N atoms (N1 and N1_a; symmetry code: (a) 2-x, 1-y, 1-z) from both the ligands coordinate to the same CuII center in the trans disposition to each other. The aliphatic –OH group remains as a pendant arm and is pointing away from the metal coordination zone. This uncoordinated oxygen atom, O1, is 8.083 Å away from the CuII ion. The complex has a τ4 value of 0 (α = O2 - Cu1 - O2_a = 180.00 and β = N1 - Cu1 - N1_a = 180.00) as a consequence of the Cu lying on a center of inversion thus supporting an assignment of distorted square planar geometry around the central metal ion (Yang et al. 2007). The complex exhibits a Cu1 – N1 bond length of 2.0146 (16) Å. In a perfectly square planar CuN4 moiety, the average CuII – N distance lies in the range of 1.980 (9) and 2.018 (9) Å (Maeda et al.,2003, Akimova et al., 2001). The Cu – N bond length value is comparable to the previously reported nearly planar CuII porphyrins (2.020 Å, 2.065 Å, 1.977 Å) (Pawlicki et al. 2007). It agrees well with the CuN2O2 monomer (τ4 = 1/5) having average CuII – N bond length range of 2.071 Å (Verma et al., 2011). The Cu1 – O2 bond distance in the complex is 1.8871 (11) Å. It is well established in the literature that in a nearly square planar geometry, the CuII – phenolic oxygen bond length lies in the range of 1.84 Å to 1.93 Å (Khandar & Nejati, 2000; Sundaravel et al., 2009). Since the Cu - O and Cu - N bond lengths are different, therefore, it can be concluded that the resultant geometry is a distorted square planar one. The pendant –OH group actively participates in H-bonding and connects two other units stabilizing the crystal lattice. As a result we have a two-dimensional extended array parallel to 201 plane with O1 - H1 - - - O1 length 2.864 (2) Å.