metal-organic compounds
Bis{μ-2,2′-[ethane-1,2-diylbis(nitrilomethylidyne)]diphenolato}dinickel(II)
aDepartment of Chemistry, Xiaogan University, Xiaogan, Hubei 432000, People's Republic of China
*Correspondence e-mail: dy9802@126.com
The 2(C16H14N2O2)2], contains an NiII cation which is coordinated by two imine N atoms and by two phenolate O atoms of the salen ligand {salen = N,N′-bis(salicylidene)ethane-1,2-diamine or 2,2′-[ethane-1,2-diylbis(nitrilomethylidyne)]diphenol}, leading to a distorted square-planar conformation. When a secondary Ni—O interaction > 2.41 Å to the neighbouring phenolate O atom is considered, two molecules are linked into a centrosymmetric dimer with an overall square-pyramidal coordination for the NiII cation. Weak π–π interactions with a shortest interplanar distance of 3.704 Å help to stabilize the crystal structure.
of the title compound, [NiExperimental
Crystal data
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Refinement
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Data collection: SMART (Bruker, 2001); cell SAINT (Bruker, 2001); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL ((Bruker, 2001); software used to prepare material for publication: SHELXTL.
Supporting information
https://doi.org/10.1107/S1600536807065506/wm2168sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536807065506/wm2168Isup2.hkl
Compound (I) was prepared by adding Ni(Ac)2.2H2O (0.110 g, 0.5 mmol) to a solution of H2(salen) 0.122 mg (0.5 mmol) in methanol (20 mL) and DMF (20 ml). After stirring the mixture for 2 h, the solution was filtered and kept for several days at ambient temperature to evaporate. Brown block-like crystals were obtained.
H atoms were placed in geometrically idealized positions and were refined in the riding mode with C–H = 0.97Å and Uiso(H)=1.5Ueq(C) for C14 and C15. All other H atoms were refined with C–H = 0.93Å and Uiso(H) = 1.2Ueq(C).
A review on metal-salen complexes in catalysis was given recently by Cozzi (2004). Herein, we report on synthesis and
of [Ni(salen)]2, (I).As shown in Fig. 1, the molecular structure of (I) is made up of a centrosymmetric dimer. The NiII cation is surrounded by two N atoms and two O atoms from the salen ligands leading to a distorted square coordination with mean Ni—O distances of 1.927 Å, and somewhat longer mean Ni—N distances of 1.952 Å. Secondary Ni1—O1(-x, y, 1/2 - z) interactions of 2.4106 (11) Å of one salen ligand to the neighbouring NiII center link two molecules to a centrosymmetric dimer with an Ni1···Ni1(-x, y, 1/2 - z) separation of 3.1946 (4) Å. The resulting overall coordination sphere of the NiII cation can thus be described as a distorted square pyramid.
As shown in Fig. 2, there are weak π-π interactions, with plane-to-plane distances and displacement angles for the planes Cg4···Cg5 and Cg5···Cg6 of 3.704 Å and 11.85 °, and 4.022 Å and 6.72 °, respectively. The planes Cg4, Cg5 and Cg6 consist of atoms C3—O2/N1, C1—C6 and C7—C12.
For a review on metal–salen complexes used in catalysis, see: Cozzi (2004).
Data collection: SMART (Bruker, 2001); cell
SAINT (Bruker, 2001); data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL ((Bruker, 2001); software used to prepare material for publication: SHELXTL (Bruker, 2001).Fig. 1. The molecular structure of (I), showing displacement ellipsoids at the 30% probability level [symmetry code: (i) -x, y, 1/2 - z]. | |
Fig. 2. The packing diagram of (I). |
[Ni2(C16H14N2O2)2] | F(000) = 1344 |
Mr = 650.00 | Dx = 1.593 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -C 2yc | Cell parameters from 3127 reflections |
a = 26.639 (2) Å | θ = 2.8–26.6° |
b = 6.9775 (6) Å | µ = 1.44 mm−1 |
c = 14.7094 (12) Å | T = 273 K |
β = 97.501 (1)° | Block, brown |
V = 2710.7 (4) Å3 | 0.34 × 0.21 × 0.07 mm |
Z = 4 |
Bruker SMART CCD diffractometer | 3090 independent reflections |
Radiation source: fine-focus sealed tube | 2607 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.023 |
φ– and ω– scans | θmax = 27.5°, θmin = 2.8° |
Absorption correction: multi-scan (SADABS; Bruker, 2001) | h = −34→32 |
Tmin = 0.641, Tmax = 0.906 | k = −7→9 |
8437 measured reflections | l = −16→19 |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.024 | H-atom parameters constrained |
wR(F2) = 0.056 | w = 1/[σ2(Fo2) + (0.0243P)2 + 0.8084P] where P = (Fo2 + 2Fc2)/3 |
S = 1.03 | (Δ/σ)max < 0.001 |
3090 reflections | Δρmax = 0.39 e Å−3 |
191 parameters | Δρmin = −0.18 e Å−3 |
0 restraints | Extinction correction: SHELXL, Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.00018 (7) |
[Ni2(C16H14N2O2)2] | V = 2710.7 (4) Å3 |
Mr = 650.00 | Z = 4 |
Monoclinic, C2/c | Mo Kα radiation |
a = 26.639 (2) Å | µ = 1.44 mm−1 |
b = 6.9775 (6) Å | T = 273 K |
c = 14.7094 (12) Å | 0.34 × 0.21 × 0.07 mm |
β = 97.501 (1)° |
Bruker SMART CCD diffractometer | 3090 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2001) | 2607 reflections with I > 2σ(I) |
Tmin = 0.641, Tmax = 0.906 | Rint = 0.023 |
8437 measured reflections |
R[F2 > 2σ(F2)] = 0.024 | 0 restraints |
wR(F2) = 0.056 | H-atom parameters constrained |
S = 1.03 | Δρmax = 0.39 e Å−3 |
3090 reflections | Δρmin = −0.18 e Å−3 |
191 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 | ||
Ni1 | 0.267171 (7) | 0.20529 (3) | 0.402119 (12) | 0.02626 (7) | |
C1 | 0.13571 (6) | 0.5214 (3) | 0.42203 (12) | 0.0431 (4) | |
H1 | 0.1505 | 0.6316 | 0.4492 | 0.052* | |
O1 | 0.21557 (4) | 0.37606 (15) | 0.43757 (7) | 0.0331 (2) | |
C3 | 0.14245 (6) | 0.1972 (2) | 0.36791 (11) | 0.0381 (4) | |
C2 | 0.16650 (6) | 0.3629 (2) | 0.40947 (10) | 0.0333 (3) | |
C6 | 0.08435 (7) | 0.5180 (3) | 0.39534 (14) | 0.0560 (5) | |
H6 | 0.0650 | 0.6253 | 0.4050 | 0.067* | |
C4 | 0.08991 (7) | 0.1999 (3) | 0.34122 (14) | 0.0520 (5) | |
H4 | 0.0743 | 0.0914 | 0.3138 | 0.062* | |
C5 | 0.06105 (7) | 0.3565 (3) | 0.35422 (15) | 0.0611 (6) | |
H5 | 0.0263 | 0.3551 | 0.3358 | 0.073* | |
C7 | 0.36315 (6) | 0.3962 (2) | 0.39857 (10) | 0.0341 (4) | |
C12 | 0.38590 (6) | 0.2332 (2) | 0.36206 (12) | 0.0383 (4) | |
C9 | 0.44526 (7) | 0.5552 (3) | 0.40933 (14) | 0.0560 (5) | |
H9 | 0.4651 | 0.6624 | 0.4261 | 0.067* | |
C8 | 0.39502 (7) | 0.5555 (3) | 0.42134 (13) | 0.0459 (4) | |
H8 | 0.3815 | 0.6644 | 0.4453 | 0.055* | |
C11 | 0.43741 (7) | 0.2396 (3) | 0.34965 (15) | 0.0538 (5) | |
H11 | 0.4518 | 0.1331 | 0.3251 | 0.065* | |
N1 | 0.31197 (5) | 0.03112 (18) | 0.34648 (9) | 0.0342 (3) | |
O2 | 0.31572 (4) | 0.40839 (15) | 0.41080 (8) | 0.0386 (3) | |
N2 | 0.21745 (5) | 0.00240 (18) | 0.37265 (9) | 0.0360 (3) | |
C13 | 0.35815 (6) | 0.0617 (2) | 0.33554 (11) | 0.0392 (4) | |
H13 | 0.3750 | −0.0349 | 0.3082 | 0.047* | |
C14 | 0.28630 (7) | −0.1438 (2) | 0.30878 (12) | 0.0430 (4) | |
H14A | 0.3096 | −0.2513 | 0.3158 | 0.052* | |
H14B | 0.2747 | −0.1270 | 0.2440 | 0.052* | |
C15 | 0.24182 (7) | −0.1823 (2) | 0.35987 (13) | 0.0443 (4) | |
H15A | 0.2181 | −0.2688 | 0.3250 | 0.053* | |
H15B | 0.2532 | −0.2407 | 0.4188 | 0.053* | |
C10 | 0.46695 (7) | 0.3965 (3) | 0.37237 (16) | 0.0618 (6) | |
H10 | 0.5009 | 0.3974 | 0.3634 | 0.074* | |
C16 | 0.16935 (7) | 0.0228 (2) | 0.35544 (11) | 0.0402 (4) | |
H16 | 0.1504 | −0.0832 | 0.3332 | 0.048* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Ni1 | 0.02833 (11) | 0.02401 (11) | 0.02671 (11) | 0.00003 (8) | 0.00461 (7) | −0.00381 (8) |
C1 | 0.0403 (9) | 0.0467 (10) | 0.0431 (10) | 0.0081 (8) | 0.0082 (8) | 0.0044 (8) |
O1 | 0.0303 (6) | 0.0334 (6) | 0.0356 (6) | 0.0004 (5) | 0.0048 (4) | −0.0036 (5) |
C3 | 0.0359 (9) | 0.0435 (10) | 0.0343 (9) | −0.0052 (7) | 0.0030 (7) | 0.0054 (7) |
C2 | 0.0326 (8) | 0.0405 (9) | 0.0271 (8) | 0.0013 (7) | 0.0056 (6) | 0.0068 (7) |
C6 | 0.0404 (10) | 0.0672 (14) | 0.0615 (13) | 0.0172 (10) | 0.0112 (9) | 0.0118 (11) |
C4 | 0.0390 (10) | 0.0646 (13) | 0.0510 (12) | −0.0112 (9) | 0.0007 (8) | 0.0094 (10) |
C5 | 0.0288 (9) | 0.0842 (16) | 0.0691 (14) | 0.0010 (10) | 0.0019 (9) | 0.0164 (12) |
C7 | 0.0328 (8) | 0.0386 (9) | 0.0309 (8) | −0.0011 (7) | 0.0037 (7) | 0.0026 (7) |
C12 | 0.0357 (9) | 0.0395 (9) | 0.0403 (10) | 0.0041 (7) | 0.0066 (7) | 0.0034 (7) |
C9 | 0.0434 (11) | 0.0600 (13) | 0.0637 (13) | −0.0162 (9) | 0.0043 (9) | 0.0022 (10) |
C8 | 0.0433 (10) | 0.0445 (10) | 0.0505 (11) | −0.0054 (8) | 0.0082 (8) | −0.0047 (8) |
C11 | 0.0390 (10) | 0.0576 (12) | 0.0667 (13) | 0.0083 (9) | 0.0143 (9) | 0.0018 (10) |
N1 | 0.0396 (7) | 0.0309 (7) | 0.0323 (7) | 0.0024 (6) | 0.0052 (6) | −0.0032 (6) |
O2 | 0.0349 (6) | 0.0327 (6) | 0.0499 (7) | −0.0017 (5) | 0.0119 (5) | −0.0051 (5) |
N2 | 0.0425 (8) | 0.0318 (7) | 0.0342 (7) | −0.0048 (6) | 0.0071 (6) | −0.0026 (6) |
C13 | 0.0438 (10) | 0.0365 (9) | 0.0387 (9) | 0.0109 (7) | 0.0110 (7) | −0.0005 (7) |
C14 | 0.0542 (11) | 0.0333 (9) | 0.0419 (10) | 0.0018 (8) | 0.0083 (8) | −0.0087 (7) |
C15 | 0.0583 (12) | 0.0301 (9) | 0.0455 (10) | −0.0035 (8) | 0.0102 (9) | −0.0035 (7) |
C10 | 0.0330 (10) | 0.0720 (14) | 0.0817 (16) | −0.0024 (10) | 0.0124 (10) | 0.0065 (12) |
C16 | 0.0447 (10) | 0.0394 (9) | 0.0361 (9) | −0.0142 (8) | 0.0037 (7) | −0.0004 (7) |
Ni1—O2 | 1.9115 (11) | C12—C13 | 1.433 (2) |
Ni1—O1 | 1.9412 (10) | C9—C8 | 1.373 (3) |
Ni1—N2 | 1.9484 (13) | C9—C10 | 1.392 (3) |
Ni1—N1 | 1.9560 (13) | C9—H9 | 0.9300 |
C1—C6 | 1.373 (2) | C8—H8 | 0.9300 |
C1—C2 | 1.403 (2) | C11—C10 | 1.364 (3) |
C1—H1 | 0.9300 | C11—H11 | 0.9300 |
O1—C2 | 1.3217 (18) | N1—C13 | 1.279 (2) |
C3—C4 | 1.403 (2) | N1—C14 | 1.472 (2) |
C3—C2 | 1.421 (2) | N2—C16 | 1.281 (2) |
C3—C16 | 1.436 (2) | N2—C15 | 1.466 (2) |
C6—C5 | 1.387 (3) | C13—H13 | 0.9300 |
C6—H6 | 0.9300 | C14—C15 | 1.508 (3) |
C4—C5 | 1.364 (3) | C14—H14A | 0.9700 |
C4—H4 | 0.9300 | C14—H14B | 0.9700 |
C5—H5 | 0.9300 | C15—H15A | 0.9700 |
C7—O2 | 1.3021 (18) | C15—H15B | 0.9700 |
C7—C8 | 1.412 (2) | C10—H10 | 0.9300 |
C7—C12 | 1.426 (2) | C16—H16 | 0.9300 |
C12—C11 | 1.409 (2) | ||
O2—Ni1—O1 | 91.35 (5) | C9—C8—C7 | 122.30 (18) |
O2—Ni1—N2 | 171.05 (5) | C9—C8—H8 | 118.9 |
O1—Ni1—N2 | 91.21 (5) | C7—C8—H8 | 118.9 |
O2—Ni1—N1 | 92.53 (5) | C10—C11—C12 | 122.30 (19) |
O1—Ni1—N1 | 170.36 (5) | C10—C11—H11 | 118.8 |
N2—Ni1—N1 | 83.67 (6) | C12—C11—H11 | 118.8 |
C6—C1—C2 | 121.78 (18) | C13—N1—C14 | 119.87 (14) |
C6—C1—H1 | 119.1 | C13—N1—Ni1 | 126.75 (11) |
C2—C1—H1 | 119.1 | C14—N1—Ni1 | 113.21 (10) |
C2—O1—Ni1 | 125.41 (10) | C7—O2—Ni1 | 127.05 (10) |
C4—C3—C2 | 119.15 (16) | C16—N2—C15 | 121.38 (14) |
C4—C3—C16 | 118.13 (16) | C16—N2—Ni1 | 126.61 (12) |
C2—C3—C16 | 122.67 (15) | C15—N2—Ni1 | 111.57 (11) |
O1—C2—C1 | 118.39 (15) | N1—C13—C12 | 125.11 (15) |
O1—C2—C3 | 124.28 (15) | N1—C13—H13 | 117.4 |
C1—C2—C3 | 117.33 (15) | C12—C13—H13 | 117.4 |
C1—C6—C5 | 120.74 (18) | N1—C14—C15 | 108.46 (14) |
C1—C6—H6 | 119.6 | N1—C14—H14A | 110.0 |
C5—C6—H6 | 119.6 | C15—C14—H14A | 110.0 |
C5—C4—C3 | 122.08 (19) | N1—C14—H14B | 110.0 |
C5—C4—H4 | 119.0 | C15—C14—H14B | 110.0 |
C3—C4—H4 | 119.0 | H14A—C14—H14B | 108.4 |
C4—C5—C6 | 118.93 (17) | N2—C15—C14 | 107.30 (13) |
C4—C5—H5 | 120.5 | N2—C15—H15A | 110.3 |
C6—C5—H5 | 120.5 | C14—C15—H15A | 110.3 |
O2—C7—C8 | 118.69 (15) | N2—C15—H15B | 110.3 |
O2—C7—C12 | 124.88 (15) | C14—C15—H15B | 110.3 |
C8—C7—C12 | 116.43 (15) | H15A—C15—H15B | 108.5 |
C11—C12—C7 | 119.51 (16) | C11—C10—C9 | 118.58 (18) |
C11—C12—C13 | 117.88 (16) | C11—C10—H10 | 120.7 |
C7—C12—C13 | 122.60 (15) | C9—C10—H10 | 120.7 |
C8—C9—C10 | 120.87 (19) | N2—C16—C3 | 124.89 (15) |
C8—C9—H9 | 119.6 | N2—C16—H16 | 117.6 |
C10—C9—H9 | 119.6 | C3—C16—H16 | 117.6 |
O2—Ni1—O1—C2 | 148.07 (12) | O1—Ni1—N1—C14 | −54.8 (3) |
N2—Ni1—O1—C2 | −23.36 (12) | N2—Ni1—N1—C14 | 3.41 (11) |
N1—Ni1—O1—C2 | 34.3 (4) | C8—C7—O2—Ni1 | −170.58 (11) |
Ni1—O1—C2—C1 | −164.26 (11) | C12—C7—O2—Ni1 | 10.4 (2) |
Ni1—O1—C2—C3 | 16.4 (2) | O1—Ni1—O2—C7 | 177.25 (13) |
C6—C1—C2—O1 | −179.44 (16) | N2—Ni1—O2—C7 | −76.1 (4) |
C6—C1—C2—C3 | −0.1 (3) | N1—Ni1—O2—C7 | −11.58 (13) |
C4—C3—C2—O1 | 179.69 (15) | O2—Ni1—N2—C16 | −86.3 (4) |
C16—C3—C2—O1 | 2.5 (3) | O1—Ni1—N2—C16 | 20.29 (14) |
C4—C3—C2—C1 | 0.4 (2) | N1—Ni1—N2—C16 | −151.53 (15) |
C16—C3—C2—C1 | −176.84 (15) | O2—Ni1—N2—C15 | 86.0 (3) |
C2—C1—C6—C5 | −0.4 (3) | O1—Ni1—N2—C15 | −167.35 (11) |
C2—C3—C4—C5 | −0.3 (3) | N1—Ni1—N2—C15 | 20.84 (11) |
C16—C3—C4—C5 | 177.11 (18) | C14—N1—C13—C12 | 174.47 (15) |
C3—C4—C5—C6 | −0.2 (3) | Ni1—N1—C13—C12 | −0.4 (2) |
C1—C6—C5—C4 | 0.5 (3) | C11—C12—C13—N1 | 176.60 (17) |
O2—C7—C12—C11 | 178.16 (16) | C7—C12—C13—N1 | −4.5 (3) |
C8—C7—C12—C11 | −0.8 (2) | C13—N1—C14—C15 | 158.62 (15) |
O2—C7—C12—C13 | −0.7 (3) | Ni1—N1—C14—C15 | −25.82 (17) |
C8—C7—C12—C13 | −179.72 (15) | C16—N2—C15—C14 | 133.16 (16) |
C10—C9—C8—C7 | 1.0 (3) | Ni1—N2—C15—C14 | −39.67 (16) |
O2—C7—C8—C9 | −179.08 (17) | N1—C14—C15—N2 | 41.36 (18) |
C12—C7—C8—C9 | 0.0 (3) | C12—C11—C10—C9 | 0.2 (3) |
C7—C12—C11—C10 | 0.8 (3) | C8—C9—C10—C11 | −1.1 (3) |
C13—C12—C11—C10 | 179.71 (19) | C15—N2—C16—C3 | 178.62 (15) |
O2—Ni1—N1—C13 | 6.72 (14) | Ni1—N2—C16—C3 | −9.7 (2) |
O1—Ni1—N1—C13 | 120.4 (3) | C4—C3—C16—N2 | 176.60 (17) |
N2—Ni1—N1—C13 | 178.60 (14) | C2—C3—C16—N2 | −6.1 (3) |
O2—Ni1—N1—C14 | −168.47 (11) |
Experimental details
Crystal data | |
Chemical formula | [Ni2(C16H14N2O2)2] |
Mr | 650.00 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 273 |
a, b, c (Å) | 26.639 (2), 6.9775 (6), 14.7094 (12) |
β (°) | 97.501 (1) |
V (Å3) | 2710.7 (4) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 1.44 |
Crystal size (mm) | 0.34 × 0.21 × 0.07 |
Data collection | |
Diffractometer | Bruker SMART CCD |
Absorption correction | Multi-scan (SADABS; Bruker, 2001) |
Tmin, Tmax | 0.641, 0.906 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 8437, 3090, 2607 |
Rint | 0.023 |
(sin θ/λ)max (Å−1) | 0.650 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.024, 0.056, 1.03 |
No. of reflections | 3090 |
No. of parameters | 191 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.39, −0.18 |
Computer programs: SMART (Bruker, 2001), SAINT (Bruker, 2001), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXTL ((Bruker, 2001), SHELXTL (Bruker, 2001).
Ni1—O2 | 1.9115 (11) | Ni1—N2 | 1.9484 (13) |
Ni1—O1 | 1.9412 (10) | Ni1—N1 | 1.9560 (13) |
O2—Ni1—O1 | 91.35 (5) | O2—Ni1—N1 | 92.53 (5) |
O2—Ni1—N2 | 171.05 (5) | O1—Ni1—N1 | 170.36 (5) |
O1—Ni1—N2 | 91.21 (5) | N2—Ni1—N1 | 83.67 (6) |
Acknowledgements
This work was supported by the Natural Science Foundation of Xiaogan University (Z2008012).
References
Bruker (2001). SAINT (Version 6.45), SMART (Version 5.628), SHELXTL (Version 6.12) and SADABS (Version 2.03). Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Cozzi, P. G. (2004). Chem. Soc. Rev. 33, 410–421. Web of Science CrossRef PubMed CAS Google Scholar
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A review on metal-salen complexes in catalysis was given recently by Cozzi (2004). Herein, we report on synthesis and crystal structure of [Ni(salen)]2, (I).
As shown in Fig. 1, the molecular structure of (I) is made up of a centrosymmetric dimer. The NiII cation is surrounded by two N atoms and two O atoms from the salen ligands leading to a distorted square coordination with mean Ni—O distances of 1.927 Å, and somewhat longer mean Ni—N distances of 1.952 Å. Secondary Ni1—O1(-x, y, 1/2 - z) interactions of 2.4106 (11) Å of one salen ligand to the neighbouring NiII center link two molecules to a centrosymmetric dimer with an Ni1···Ni1(-x, y, 1/2 - z) separation of 3.1946 (4) Å. The resulting overall coordination sphere of the NiII cation can thus be described as a distorted square pyramid.
As shown in Fig. 2, there are weak π-π interactions, with plane-to-plane distances and displacement angles for the planes Cg4···Cg5 and Cg5···Cg6 of 3.704 Å and 11.85 °, and 4.022 Å and 6.72 °, respectively. The planes Cg4, Cg5 and Cg6 consist of atoms C3—O2/N1, C1—C6 and C7—C12.