Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S010827010500034X/av1222sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S010827010500034X/av1222Isup2.hkl |
CCDC reference: 264794
Cu(CH3C≡N)4(ClO4) (1 mmol) was reacted with dibenzyl-(6-methyl-2-pyridylmethyl)amine (1 mmol) in moist methanol to give the copper(I) complex which, on reaction with oxygen, afforded the title dinuclear bis-hydroxo-bridged copper(II) complex. X-ray diffraction quality crystals of (I) were obtained by recrystallization from an acetonitrile–methanol mixture (Ratio?).
During the last stages of refinement, a certain disorder of the perchlorate O atoms was evident. This was modelled considering two partially occupied positions for the perchlorate anion, with occupancy factors of 0.60 and 0.40, respectively. All the Cl—O distances in each perchlorate position were set equal to common parameters, which were refined and finally set as 1.39 and 1.43 Å, respectively. The H atoms of the organic amine were introduced in calculated positions and then refined using the riding model, with C—H distances of 0.93 Å and with Uiso(H) = 1.2Ueq(C). The hydroxy H atom was located by difference synthesis during the last stages of the structure completion. Its coordinates were not subsequently refined.
The coordination chemistry of copper complexes is a subject of continuing importance, mainly in relation to the structure and reactivity of the active site in copper-containing metalloproteins. The reactivity of copper(I) complexes towards molecular oxygen is also relevant to the utilization of atmospheric oxygen in stoichiometric or catalytic oxidations of organic substrates mediated by copper complexes (Karlin et al., 1999), as well as to understanding the mechanism of dioxygen utilization by copper proteins (Karlin & Zuberbuhler, 1999; Kopf & Karlin, 2000; Solomon et al., 1996). Recent advances (Kitajima & Moro-oka, 1994; Suzuki et al., 2000) have shown that the structure and reactivity of copper(I) complexes are significantly modified by slight perturbations in the supporting ligands.
Recently, we reported that the oxygenation of a methanol solution of the copper(I) complex with the bidentate ligand dibenzyl-(6-methyl-2-pyridylmethyl)amine (BiBzMePMA) at room temperature leads to the bis-methoxo-bridged copper(II) complex [Cu(BiBzMePMA)]2-µ2(OCH3)2, which has been fully characterized, both magnetically and structurally (Rojas et al., 2004). Here, we report the crystal structure of the analogous bis-hydroxo-bridged compound, [Cu(BiBzMePMA)]2-µ2(OH)2, (I), resulting from the same synthetic procedure, but in the presence of traces of water in the solvent.
The molecular structure of complex (I) is defined by two [CuL]2+ units [where L is dibenzyl-(6-methyl-2-pyridylmethyl)amine], µ2-bridged by two hydroxyl groups, in such a way as to define a central N2CuO2CuN2 core. Additionally, there is an acetonitrile (CH3C≡N) molecule completing pentacoordination of each Cu atom, thus defining a slightly distorted square-based pyramidal coordination for the metal centres. The basal square of the pyramid is defined by two amine N atoms (N1 and N2) and two hydroxyl O atoms [O1 and O1i; symmetry code: (i) 1 - x, -y, 2 - z Please check added symmetry code], while the acetonitrile atom N3 occupies the apical position. This N atom deviates by 3.7° from the perpendicular to the basal-plane position.
The Cu—Nacetonitrile distance is 2.476 (5) Å, a rather long value for this kind of bond, which is usually in the range 2.00–2.50 Å. A shorter value of about 2 Å has been described for [Cu2(L2)(CH3CN)2]4+, where L is tetrakis(1-methylimidazol-2-ylmethyl)-2-hydroxy-1,3-diaminopropane (Gentschev et al., 2000), while a distance of 2.322 (6) Å has been described for [Cu2(µ-oxalato)(dipyridylamino)2(CH3CN)2](ClO4)2 (Du et al., 2003). The linear acetonitrile molecule defines an angle of 24.8° with the Cu—N3 line [Cu—N3—C22 155.2 (4)°], which can probably be ascribed to packing effects (Murthy et al., 2001).
The two edge-sharing pyramids have their apical acetonitrile N atoms lying on opposite sides of the CuO2Cu plane, in a trans arrangement, as required by the inversion centre at the middle of the Cu···Cu distance. A cis arrangement was found in the macrocyclic complex [Cu2L(CH3C≡ N)2], where L is 3,7,10,11,14,18,21,22-octaazatricyclo[18.2.2.29,12]-hexacosa- 1(22),2,7,9,11,13,18,20,23,25-decaene (Brooker et al., 1996).
The Cu···Cu distance is 2.9522 (9) Å, a rather short value for this kind of complex (Rojas et al., 2004). Consistently, the Cu—O—Cu angle is 100.24 (12)°. The atom sequence Cu—O1—Cui—O1i is a rather regular parallogram, with sides of about 1.92 Å. The Cu—O1 and Cu—O1i distances are 1.923 (3) and 1.920 (3) Å, respectively. The hydroxy H atoms deviate from the Cu–O plane by 45.5°, a value which can be affected by packing effects, i.e. interaction between the hydroxy H atoms and the O atoms of the perchlorate counteranion. The distances between atom H1 and the partially occupied perchlorate atoms O5A and O5B are 1.974 and 2.196 Å, respectively. The deviation of the hydroxy H atom from planarity has been described as an important factor which determines the magnetic coupling exchange of binuclear copper(II) complexes (Ruiz et al., 1997).
Data collection: SMART-NT (Bruker, 2001); data reduction: SAINT-NT (Bruker, 1999); program(s) used to solve structure: SHELXTL-NT (Bruker, 1999); program(s) used to refine structure: SHELXTL-NT; molecular graphics: SHELXTL-NT; software used to prepare material for publication: SHELXTL-NT.
[Cu2(OH)2(C2H3N)2(C21H22N2)2](ClO4)2 | F(000) = 1084 |
Mr = 1046.94 | Dx = 1.462 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 3378 reflections |
a = 10.1453 (10) Å | θ = 4.6–46.7° |
b = 20.0868 (19) Å | µ = 1.07 mm−1 |
c = 12.0925 (12) Å | T = 571 K |
β = 105.193 (2)° | Prism, blue |
V = 2378.2 (4) Å3 | 0.55 × 0.55 × 0.45 mm |
Z = 2 |
Siemens SMART CCD area-detector diffractometer | 4218 independent reflections |
Radiation source: fine-focus sealed tube | 3006 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.030 |
φ and ω scans | θmax = 25.1°, θmin = 2.0° |
Absorption correction: part of the refinement model (ΔF) (SADABS in SAINT-NT; Bruker, 1999) | h = −11→12 |
Tmin = 0.572, Tmax = 0.618 | k = −23→23 |
12077 measured reflections | l = −14→12 |
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)] = 0.057 | Hydrogen site location: mixed |
wR(F2) = 0.183 | H-atom parameters constrained |
S = 1.04 | w = 1/[σ2(Fo2) + (0.1158P)2] where P = (Fo2 + 2Fc2)/3 |
4218 reflections | (Δ/σ)max < 0.001 |
299 parameters | Δρmax = 0.76 e Å−3 |
8 restraints | Δρmin = −0.74 e Å−3 |
[Cu2(OH)2(C2H3N)2(C21H22N2)2](ClO4)2 | V = 2378.2 (4) Å3 |
Mr = 1046.94 | Z = 2 |
Monoclinic, P21/c | Mo Kα radiation |
a = 10.1453 (10) Å | µ = 1.07 mm−1 |
b = 20.0868 (19) Å | T = 571 K |
c = 12.0925 (12) Å | 0.55 × 0.55 × 0.45 mm |
β = 105.193 (2)° |
Siemens SMART CCD area-detector diffractometer | 4218 independent reflections |
Absorption correction: part of the refinement model (ΔF) (SADABS in SAINT-NT; Bruker, 1999) | 3006 reflections with I > 2σ(I) |
Tmin = 0.572, Tmax = 0.618 | Rint = 0.030 |
12077 measured reflections |
R[F2 > 2σ(F2)] = 0.057 | 8 restraints |
wR(F2) = 0.183 | H-atom parameters constrained |
S = 1.04 | Δρmax = 0.76 e Å−3 |
4218 reflections | Δρmin = −0.74 e Å−3 |
299 parameters |
Experimental. Each frame was mesured during 10 s, using 0.3 /% between frames. |
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 | Occ. (<1) | |
Cu | 0.39369 (5) | −0.00309 (2) | 0.89022 (4) | 0.0369 (2) | |
O1 | 0.5473 (3) | 0.05049 (14) | 0.9675 (2) | 0.0431 (7) | |
H1 | 0.6163 | 0.0577 | 0.9285 | 0.10 (2)* | |
N1 | 0.2476 (4) | −0.06543 (16) | 0.7961 (3) | 0.0402 (8) | |
C1 | 0.3294 (6) | −0.1707 (2) | 0.8914 (5) | 0.0691 (15) | |
H1A | 0.4164 | −0.1487 | 0.9096 | 0.104* | |
H1B | 0.3387 | −0.2145 | 0.8626 | 0.104* | |
H1C | 0.2973 | −0.1740 | 0.9591 | 0.104* | |
C2 | 0.2299 (5) | −0.1318 (2) | 0.8028 (4) | 0.0490 (11) | |
C3 | 0.1183 (6) | −0.1628 (3) | 0.7287 (5) | 0.0651 (15) | |
H3 | 0.1071 | −0.2086 | 0.7333 | 0.078* | |
C4 | 0.0259 (6) | −0.1268 (3) | 0.6500 (5) | 0.0709 (16) | |
H4 | −0.0502 | −0.1474 | 0.6026 | 0.085* | |
C5 | 0.0461 (5) | −0.0597 (3) | 0.6412 (4) | 0.0596 (14) | |
H5 | −0.0156 | −0.0341 | 0.5874 | 0.072* | |
C6 | 0.1585 (4) | −0.0310 (2) | 0.7130 (4) | 0.0430 (11) | |
C7 | 0.1885 (4) | 0.0415 (2) | 0.7032 (4) | 0.0437 (11) | |
H7A | 0.1569 | 0.0550 | 0.6237 | 0.052* | |
H7B | 0.1387 | 0.0672 | 0.7469 | 0.052* | |
N2 | 0.3366 (3) | 0.05635 (16) | 0.7457 (3) | 0.0383 (8) | |
C8 | 0.4144 (5) | 0.0414 (2) | 0.6595 (4) | 0.0508 (12) | |
H8A | 0.5031 | 0.0629 | 0.6834 | 0.061* | |
H8B | 0.3661 | 0.0606 | 0.5865 | 0.061* | |
C9 | 0.4352 (5) | −0.0315 (3) | 0.6428 (4) | 0.0531 (12) | |
C10 | 0.3506 (6) | −0.0668 (3) | 0.5540 (5) | 0.0709 (16) | |
H10 | 0.2838 | −0.0451 | 0.4982 | 0.085* | |
C11 | 0.3674 (8) | −0.1363 (4) | 0.5493 (7) | 0.096 (2) | |
H11 | 0.3098 | −0.1606 | 0.4908 | 0.116* | |
C12 | 0.4658 (9) | −0.1681 (4) | 0.6285 (8) | 0.098 (2) | |
H12 | 0.4736 | −0.2142 | 0.6259 | 0.117* | |
C13 | 0.5538 (7) | −0.1326 (3) | 0.7123 (6) | 0.0837 (19) | |
H13 | 0.6249 | −0.1542 | 0.7642 | 0.100* | |
C14 | 0.5378 (6) | −0.0651 (3) | 0.7204 (5) | 0.0640 (14) | |
H14 | 0.5971 | −0.0416 | 0.7790 | 0.077* | |
C15 | 0.3537 (4) | 0.12901 (19) | 0.7795 (4) | 0.0434 (11) | |
H15A | 0.3144 | 0.1362 | 0.8435 | 0.052* | |
H15B | 0.4505 | 0.1387 | 0.8058 | 0.052* | |
C16 | 0.2899 (4) | 0.1773 (2) | 0.6862 (4) | 0.0437 (11) | |
C17 | 0.1583 (5) | 0.2006 (2) | 0.6742 (4) | 0.0511 (12) | |
H17 | 0.1092 | 0.1866 | 0.7249 | 0.061* | |
C18 | 0.0996 (5) | 0.2446 (2) | 0.5868 (5) | 0.0580 (14) | |
H18 | 0.0103 | 0.2589 | 0.5782 | 0.070* | |
C19 | 0.1712 (6) | 0.2671 (2) | 0.5136 (4) | 0.0588 (14) | |
H19 | 0.1316 | 0.2971 | 0.4559 | 0.071* | |
C20 | 0.3018 (6) | 0.2453 (2) | 0.5256 (5) | 0.0654 (15) | |
H20 | 0.3506 | 0.2601 | 0.4751 | 0.078* | |
C21 | 0.3619 (5) | 0.2013 (2) | 0.6121 (5) | 0.0558 (13) | |
H21 | 0.4516 | 0.1877 | 0.6206 | 0.067* | |
N3 | 0.2201 (4) | 0.0519 (2) | 0.9695 (4) | 0.0599 (11) | |
C22 | 0.1587 (5) | 0.0594 (2) | 1.0321 (5) | 0.0540 (13) | |
C23 | 0.0792 (7) | 0.0684 (3) | 1.1156 (6) | 0.0842 (19) | |
H23A | 0.0011 | 0.0957 | 1.0830 | 0.126* | |
H23B | 0.1348 | 0.0896 | 1.1829 | 0.126* | |
H23C | 0.0495 | 0.0258 | 1.1359 | 0.126* | |
ClA | 0.81252 (13) | 0.12494 (7) | 0.80005 (13) | 0.0693 (5) | 0.60 |
O2A | 0.7094 (8) | 0.1640 (4) | 0.7324 (9) | 0.116 (4)* | 0.60 |
O3A | 0.9310 (7) | 0.1617 (5) | 0.8419 (11) | 0.143 (4)* | 0.60 |
O4A | 0.8574 (11) | 0.0838 (5) | 0.7248 (8) | 0.147 (4)* | 0.60 |
O5A | 0.7786 (10) | 0.0821 (5) | 0.8762 (9) | 0.114 (3)* | 0.60 |
ClB | 0.81252 (13) | 0.12494 (7) | 0.80005 (13) | 0.0693 (5) | 0.40 |
O2B | 0.6926 (11) | 0.1652 (8) | 0.7825 (17) | 0.141 (7)* | 0.40 |
O3B | 0.8673 (19) | 0.1548 (9) | 0.9098 (8) | 0.168 (7)* | 0.40 |
O4B | 0.910 (2) | 0.1394 (15) | 0.737 (2) | 0.237 (11)* | 0.40 |
O5B | 0.7293 (16) | 0.0725 (8) | 0.7984 (15) | 0.131 (5)* | 0.40 |
U11 | U22 | U33 | U12 | U13 | U23 | |
Cu | 0.0420 (3) | 0.0320 (3) | 0.0337 (3) | −0.0029 (2) | 0.0048 (2) | 0.0042 (2) |
O1 | 0.0433 (16) | 0.0435 (18) | 0.0391 (17) | −0.0092 (13) | 0.0047 (14) | 0.0085 (14) |
N1 | 0.052 (2) | 0.0341 (19) | 0.037 (2) | −0.0056 (16) | 0.0158 (17) | −0.0031 (16) |
C1 | 0.097 (4) | 0.035 (3) | 0.074 (4) | 0.000 (3) | 0.020 (3) | −0.001 (3) |
C2 | 0.068 (3) | 0.034 (2) | 0.050 (3) | −0.008 (2) | 0.025 (2) | −0.007 (2) |
C3 | 0.091 (4) | 0.046 (3) | 0.067 (4) | −0.023 (3) | 0.035 (3) | −0.018 (3) |
C4 | 0.083 (4) | 0.061 (3) | 0.062 (4) | −0.028 (3) | 0.007 (3) | −0.018 (3) |
C5 | 0.060 (3) | 0.068 (3) | 0.046 (3) | −0.017 (3) | 0.004 (2) | −0.003 (3) |
C6 | 0.050 (3) | 0.042 (3) | 0.035 (2) | −0.007 (2) | 0.008 (2) | −0.005 (2) |
C7 | 0.047 (2) | 0.039 (2) | 0.039 (2) | −0.0062 (19) | 0.001 (2) | 0.002 (2) |
N2 | 0.048 (2) | 0.0328 (18) | 0.0327 (19) | −0.0032 (15) | 0.0078 (15) | 0.0013 (15) |
C8 | 0.063 (3) | 0.046 (3) | 0.046 (3) | −0.001 (2) | 0.019 (2) | 0.007 (2) |
C9 | 0.066 (3) | 0.053 (3) | 0.047 (3) | −0.001 (3) | 0.028 (2) | −0.005 (2) |
C10 | 0.092 (4) | 0.072 (4) | 0.052 (3) | −0.002 (3) | 0.023 (3) | −0.013 (3) |
C11 | 0.129 (6) | 0.078 (5) | 0.087 (5) | −0.006 (4) | 0.038 (5) | −0.045 (4) |
C12 | 0.127 (6) | 0.065 (4) | 0.116 (6) | 0.021 (4) | 0.059 (5) | −0.012 (4) |
C13 | 0.084 (4) | 0.065 (4) | 0.103 (5) | 0.020 (3) | 0.027 (4) | −0.003 (4) |
C14 | 0.066 (3) | 0.062 (3) | 0.066 (4) | 0.012 (3) | 0.020 (3) | −0.002 (3) |
C15 | 0.052 (3) | 0.032 (2) | 0.042 (3) | −0.0047 (19) | 0.006 (2) | 0.0004 (19) |
C16 | 0.055 (3) | 0.031 (2) | 0.043 (3) | −0.0048 (19) | 0.010 (2) | 0.0006 (19) |
C17 | 0.058 (3) | 0.047 (3) | 0.053 (3) | 0.005 (2) | 0.024 (2) | 0.000 (2) |
C18 | 0.056 (3) | 0.043 (3) | 0.071 (4) | 0.015 (2) | 0.008 (3) | −0.001 (3) |
C19 | 0.084 (4) | 0.036 (3) | 0.051 (3) | 0.009 (2) | 0.008 (3) | 0.009 (2) |
C20 | 0.084 (4) | 0.051 (3) | 0.068 (4) | 0.003 (3) | 0.032 (3) | 0.023 (3) |
C21 | 0.054 (3) | 0.045 (3) | 0.073 (3) | 0.002 (2) | 0.024 (3) | 0.015 (3) |
N3 | 0.066 (3) | 0.059 (3) | 0.060 (3) | 0.008 (2) | 0.027 (2) | 0.008 (2) |
C22 | 0.064 (3) | 0.041 (3) | 0.060 (3) | 0.002 (2) | 0.022 (3) | 0.004 (2) |
C23 | 0.099 (5) | 0.080 (4) | 0.092 (5) | 0.002 (3) | 0.060 (4) | −0.006 (3) |
ClA | 0.0505 (7) | 0.0669 (9) | 0.0814 (10) | −0.0146 (6) | 0.0011 (6) | 0.0250 (7) |
ClB | 0.0505 (7) | 0.0669 (9) | 0.0814 (10) | −0.0146 (6) | 0.0011 (6) | 0.0250 (7) |
Cu—O1i | 1.920 (3) | C10—C11 | 1.408 (8) |
Cu—O1 | 1.923 (3) | C10—H10 | 0.9300 |
Cu—N1 | 2.044 (3) | C11—C12 | 1.350 (10) |
Cu—N2 | 2.070 (3) | C11—H11 | 0.9300 |
Cu—N3 | 2.476 (5) | C12—C13 | 1.362 (9) |
Cu—Cui | 2.9522 (9) | C12—H12 | 0.9300 |
O1—Cui | 1.920 (3) | C13—C14 | 1.372 (8) |
O1—H1 | 0.952 | C13—H13 | 0.9300 |
N1—C2 | 1.350 (5) | C14—H14 | 0.9300 |
N1—C6 | 1.352 (5) | C15—C16 | 1.500 (6) |
C1—C2 | 1.487 (7) | C15—H15A | 0.9700 |
C1—H1A | 0.9600 | C15—H15B | 0.9700 |
C1—H1B | 0.9600 | C16—C21 | 1.382 (6) |
C1—H1C | 0.9600 | C16—C17 | 1.386 (6) |
C2—C3 | 1.393 (7) | C17—C18 | 1.387 (7) |
C3—C4 | 1.356 (8) | C17—H17 | 0.9300 |
C3—H3 | 0.9300 | C18—C19 | 1.361 (7) |
C4—C5 | 1.373 (7) | C18—H18 | 0.9300 |
C4—H4 | 0.9300 | C19—C20 | 1.367 (7) |
C5—C6 | 1.366 (6) | C19—H19 | 0.9300 |
C5—H5 | 0.9300 | C20—C21 | 1.384 (6) |
C6—C7 | 1.500 (6) | C20—H20 | 0.9300 |
C7—N2 | 1.485 (5) | C21—H21 | 0.9300 |
C7—H7A | 0.9700 | N3—C22 | 1.109 (6) |
C7—H7B | 0.9700 | C22—C23 | 1.459 (8) |
N2—C8 | 1.494 (6) | C23—H23A | 0.9600 |
N2—C15 | 1.513 (5) | C23—H23B | 0.9600 |
C8—C9 | 1.501 (7) | C23—H23C | 0.9600 |
C8—H8A | 0.9700 | ClA—O5A | 1.369 (10) |
C8—H8B | 0.9700 | ClA—O3A | 1.3890 (10) |
C9—C14 | 1.381 (7) | ClA—O2A | 1.3900 (7) |
C9—C10 | 1.382 (7) | ClA—O4A | 1.3911 (10) |
O1i—Cu—O1 | 79.61 (13) | C10—C9—C8 | 121.7 (5) |
O1i—Cu—N1 | 101.86 (13) | C9—C10—C11 | 118.9 (6) |
O1—Cu—N1 | 172.23 (14) | C9—C10—H10 | 120.6 |
O1i—Cu—N2 | 174.44 (12) | C11—C10—H10 | 120.6 |
O1—Cu—N2 | 95.69 (12) | C12—C11—C10 | 121.0 (6) |
N1—Cu—N2 | 83.20 (14) | C12—C11—H11 | 119.5 |
O1i—Cu—N3 | 87.74 (14) | C10—C11—H11 | 119.5 |
O1—Cu—N3 | 97.49 (14) | C11—C12—C13 | 119.9 (6) |
N1—Cu—N3 | 90.21 (14) | C11—C12—H12 | 120.1 |
N2—Cu—N3 | 89.97 (14) | C13—C12—H12 | 120.1 |
Cui—O1—Cu | 100.39 (13) | C12—C13—C14 | 120.2 (6) |
Cui—O1—H1 | 115.0 | C12—C13—H13 | 119.9 |
Cu—O1—H1 | 116.9 | C14—C13—H13 | 119.9 |
C2—N1—C6 | 118.4 (4) | C13—C14—C9 | 121.1 (6) |
C2—C1—H1A | 109.5 | C13—C14—H14 | 119.4 |
C2—C1—H1B | 109.5 | C9—C14—H14 | 119.4 |
H1A—C1—H1B | 109.5 | C16—C15—N2 | 115.1 (3) |
C2—C1—H1C | 109.5 | C16—C15—H15A | 108.5 |
H1A—C1—H1C | 109.5 | N2—C15—H15A | 108.5 |
H1B—C1—H1C | 109.5 | C16—C15—H15B | 108.5 |
N1—C2—C3 | 120.1 (5) | N2—C15—H15B | 108.5 |
N1—C2—C1 | 119.1 (4) | H15A—C15—H15B | 107.5 |
C3—C2—C1 | 120.8 (4) | C21—C16—C17 | 118.2 (4) |
C4—C3—C2 | 120.6 (5) | C21—C16—C15 | 121.0 (4) |
C4—C3—H3 | 119.7 | C17—C16—C15 | 120.7 (4) |
C2—C3—H3 | 119.7 | C16—C17—C18 | 120.3 (5) |
C3—C4—C5 | 119.2 (5) | C16—C17—H17 | 119.8 |
C3—C4—H4 | 120.4 | C18—C17—H17 | 119.8 |
C5—C4—H4 | 120.4 | C19—C18—C17 | 120.7 (5) |
C6—C5—C4 | 118.8 (5) | C19—C18—H18 | 119.6 |
C6—C5—H5 | 120.6 | C17—C18—H18 | 119.6 |
C4—C5—H5 | 120.6 | C18—C19—C20 | 119.5 (5) |
N1—C6—C5 | 122.8 (4) | C18—C19—H19 | 120.2 |
N1—C6—C7 | 116.4 (3) | C20—C19—H19 | 120.2 |
C5—C6—C7 | 120.8 (4) | C19—C20—C21 | 120.5 (5) |
N2—C7—C6 | 112.1 (3) | C19—C20—H20 | 119.7 |
N2—C7—H7A | 109.2 | C21—C20—H20 | 119.7 |
C6—C7—H7A | 109.2 | C20—C21—C16 | 120.6 (5) |
N2—C7—H7B | 109.2 | C20—C21—H21 | 119.7 |
C6—C7—H7B | 109.2 | C16—C21—H21 | 119.7 |
H7A—C7—H7B | 107.9 | C22—N3—Cu | 155.2 (4) |
C7—N2—C8 | 112.9 (3) | N3—C22—C23 | 179.2 (6) |
C7—N2—C15 | 108.7 (3) | C22—C23—H23A | 109.5 |
C8—N2—C15 | 109.7 (3) | C22—C23—H23B | 109.5 |
C7—N2—Cu | 102.1 (2) | H23A—C23—H23B | 109.5 |
C8—N2—Cu | 113.1 (3) | C22—C23—H23C | 109.5 |
C15—N2—Cu | 110.0 (2) | H23A—C23—H23C | 109.5 |
N2—C8—C9 | 114.0 (4) | H23B—C23—H23C | 109.5 |
N2—C8—H8A | 108.7 | O5A—ClA—O3A | 115.8 (7) |
C9—C8—H8A | 108.7 | O5A—ClA—O2A | 117.9 (6) |
N2—C8—H8B | 108.7 | O3A—ClA—O2A | 111.1 (6) |
C9—C8—H8B | 108.7 | O5A—ClA—O4A | 104.5 (7) |
H8A—C8—H8B | 107.6 | O3A—ClA—O4A | 98.9 (7) |
C14—C9—C10 | 118.7 (5) | O2A—ClA—O4A | 106.0 (7) |
C14—C9—C8 | 119.5 (4) |
Symmetry code: (i) −x+1, −y, −z+2. |
Experimental details
Crystal data | |
Chemical formula | [Cu2(OH)2(C2H3N)2(C21H22N2)2](ClO4)2 |
Mr | 1046.94 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 571 |
a, b, c (Å) | 10.1453 (10), 20.0868 (19), 12.0925 (12) |
β (°) | 105.193 (2) |
V (Å3) | 2378.2 (4) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 1.07 |
Crystal size (mm) | 0.55 × 0.55 × 0.45 |
Data collection | |
Diffractometer | Siemens SMART CCD area-detector |
Absorption correction | Part of the refinement model (ΔF) (SADABS in SAINT-NT; Bruker, 1999) |
Tmin, Tmax | 0.572, 0.618 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 12077, 4218, 3006 |
Rint | 0.030 |
(sin θ/λ)max (Å−1) | 0.597 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.057, 0.183, 1.04 |
No. of reflections | 4218 |
No. of parameters | 299 |
No. of restraints | 8 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.76, −0.74 |
Computer programs: SMART-NT (Bruker, 2001), SAINT-NT (Bruker, 1999), SHELXTL-NT (Bruker, 1999), SHELXTL-NT.
Cu—O1i | 1.920 (3) | Cu—N2 | 2.070 (3) |
Cu—O1 | 1.923 (3) | Cu—N3 | 2.476 (5) |
Cu—N1 | 2.044 (3) | Cu—Cui | 2.9522 (9) |
O1i—Cu—O1 | 79.61 (13) | O1—Cu—N3 | 97.49 (14) |
O1i—Cu—N1 | 101.86 (13) | N1—Cu—N3 | 90.21 (14) |
O1—Cu—N1 | 172.23 (14) | N2—Cu—N3 | 89.97 (14) |
O1i—Cu—N2 | 174.44 (12) | Cui—O1—Cu | 100.39 (13) |
O1—Cu—N2 | 95.69 (12) | Cui—O1—H1 | 115.0 |
N1—Cu—N2 | 83.20 (14) | Cu—O1—H1 | 116.9 |
O1i—Cu—N3 | 87.74 (14) | C22—N3—Cu | 155.2 (4) |
Symmetry code: (i) −x+1, −y, −z+2. |
The coordination chemistry of copper complexes is a subject of continuing importance, mainly in relation to the structure and reactivity of the active site in copper-containing metalloproteins. The reactivity of copper(I) complexes towards molecular oxygen is also relevant to the utilization of atmospheric oxygen in stoichiometric or catalytic oxidations of organic substrates mediated by copper complexes (Karlin et al., 1999), as well as to understanding the mechanism of dioxygen utilization by copper proteins (Karlin & Zuberbuhler, 1999; Kopf & Karlin, 2000; Solomon et al., 1996). Recent advances (Kitajima & Moro-oka, 1994; Suzuki et al., 2000) have shown that the structure and reactivity of copper(I) complexes are significantly modified by slight perturbations in the supporting ligands.
Recently, we reported that the oxygenation of a methanol solution of the copper(I) complex with the bidentate ligand dibenzyl-(6-methyl-2-pyridylmethyl)amine (BiBzMePMA) at room temperature leads to the bis-methoxo-bridged copper(II) complex [Cu(BiBzMePMA)]2-µ2(OCH3)2, which has been fully characterized, both magnetically and structurally (Rojas et al., 2004). Here, we report the crystal structure of the analogous bis-hydroxo-bridged compound, [Cu(BiBzMePMA)]2-µ2(OH)2, (I), resulting from the same synthetic procedure, but in the presence of traces of water in the solvent.
The molecular structure of complex (I) is defined by two [CuL]2+ units [where L is dibenzyl-(6-methyl-2-pyridylmethyl)amine], µ2-bridged by two hydroxyl groups, in such a way as to define a central N2CuO2CuN2 core. Additionally, there is an acetonitrile (CH3C≡N) molecule completing pentacoordination of each Cu atom, thus defining a slightly distorted square-based pyramidal coordination for the metal centres. The basal square of the pyramid is defined by two amine N atoms (N1 and N2) and two hydroxyl O atoms [O1 and O1i; symmetry code: (i) 1 - x, -y, 2 - z Please check added symmetry code], while the acetonitrile atom N3 occupies the apical position. This N atom deviates by 3.7° from the perpendicular to the basal-plane position.
The Cu—Nacetonitrile distance is 2.476 (5) Å, a rather long value for this kind of bond, which is usually in the range 2.00–2.50 Å. A shorter value of about 2 Å has been described for [Cu2(L2)(CH3CN)2]4+, where L is tetrakis(1-methylimidazol-2-ylmethyl)-2-hydroxy-1,3-diaminopropane (Gentschev et al., 2000), while a distance of 2.322 (6) Å has been described for [Cu2(µ-oxalato)(dipyridylamino)2(CH3CN)2](ClO4)2 (Du et al., 2003). The linear acetonitrile molecule defines an angle of 24.8° with the Cu—N3 line [Cu—N3—C22 155.2 (4)°], which can probably be ascribed to packing effects (Murthy et al., 2001).
The two edge-sharing pyramids have their apical acetonitrile N atoms lying on opposite sides of the CuO2Cu plane, in a trans arrangement, as required by the inversion centre at the middle of the Cu···Cu distance. A cis arrangement was found in the macrocyclic complex [Cu2L(CH3C≡ N)2], where L is 3,7,10,11,14,18,21,22-octaazatricyclo[18.2.2.29,12]-hexacosa- 1(22),2,7,9,11,13,18,20,23,25-decaene (Brooker et al., 1996).
The Cu···Cu distance is 2.9522 (9) Å, a rather short value for this kind of complex (Rojas et al., 2004). Consistently, the Cu—O—Cu angle is 100.24 (12)°. The atom sequence Cu—O1—Cui—O1i is a rather regular parallogram, with sides of about 1.92 Å. The Cu—O1 and Cu—O1i distances are 1.923 (3) and 1.920 (3) Å, respectively. The hydroxy H atoms deviate from the Cu–O plane by 45.5°, a value which can be affected by packing effects, i.e. interaction between the hydroxy H atoms and the O atoms of the perchlorate counteranion. The distances between atom H1 and the partially occupied perchlorate atoms O5A and O5B are 1.974 and 2.196 Å, respectively. The deviation of the hydroxy H atom from planarity has been described as an important factor which determines the magnetic coupling exchange of binuclear copper(II) complexes (Ruiz et al., 1997).