metal-organic compounds
{2,2′-[Ethane-1,2-diylbis(nitrilomethanylylidene)]diphenolato}(isopropanolato)aluminium dichloromethane hemisolvate
aDepartment of Chemistry, M.V. Lomonosov Moscow State University, Leninskie Gory 1/3, Moscow 119991, Russian Federation, and bInstitute of General and Inorganic Chemistry, Russian Academy of Sciences, Leninskii prosp. 31, Moscow 119991, Russian Federation
*Correspondence e-mail: churakov@igic.ras.ru
In the title compound, [Al(C16H14N2O2)(C3H7O)]·0.5CH2Cl2, the salen complex is monomeric and the dichlormethane solvent molecule lies on a crystallographic twofold axis. The central Al atom is fivefold coordinated and possesses a square-based pyramidal environment. The Al—OAlk(ipropyl) bond [1.7404 (14) Å] is much shorter than the Al—OAr(salen) bond lengths [1.7974 (15) and 1.8094 (14) Å]. The isopropyloxo group forms an intramolecular C—H⋯N hydrogen bond. In the crystal, the complex molecules are linked by weak C—H⋯O interactions.
CCDC reference: 969040
Related literature
For general background to the chemistry affording aluminium complexes based on salen-type ligands, see: Matsumoto et al. (2007); Gurian et al. (1991); Atwood et al. (1997); Muñoz-Hernandez et al. (2000). For our previous work on main group element complexes with polydentate N,O-ligands, see: Karlov & Zaitseva (2001). For structures of related monomeric Al-salen complexes, see: Darensburg & Billodeaux (2005); Gurian et al. (1991); Pang et al. (2008). For a description of the Cambridge Structural Database, see: Allen (2002).
Experimental
Crystal data
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Data collection: APEX2 (Bruker, 2008); cell SAINT (Bruker, 2008); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.
Supporting information
CCDC reference: 969040
10.1107/S1600536813029644/fk2075sup1.cif
contains datablock I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536813029644/fk2075Isup2.hkl
Supporting information file. DOI: 10.1107/S1600536813029644/fk2075Isup3.mol
The title compound was obtained from reaction of equimolar amounts of Al(O-iPr)3 and salen in toluene at reflux as a solid.
1H NMR (CDCl3): δ 8.24 (s, 2H, N=CH), 7.40–7.33 (m, 2H, aromatic H atoms), 7.16–7.07 (m, 4H, aromatic H atoms), 6.73–6.67 (m, 2H, aromatic H atoms), 4.12–4.02 (m, 2H, NCH2), 3.75 (sept, J = 6.1 Hz, 1H, OCH), 3.65–3.58 (m, 2H, NCH2), 0.91 d (d, J = 6.1 Hz, 6H, OCHMe2) p.p.m..
13C NMR (CDCl3): δ 168.97 (N=CH), 165.78, 135.46, 132.99, 122.26, 118.74, 116.55 (aromatic carbons), 62.80 (OCH), 54.44 (NCH2), 27.33 (OCHMe2) p.p.m..
All hydrogen atoms were placed in calculated positions and refined using a riding model with C—H = 1.00 Å and Uiso(H) = 1.2Ueq(C) for methyne group; C—H = 0.99 Å and Uiso(H) = 1.2Ueq(C) for methylene groups; C—H = 0.98 Å and Uiso(H) = 1.5Ueq(C) for methyl groups; C—H = 0.95 Å and Uiso(H) = 1.2Ueq(C) for aromatic H atoms.
Data collection: APEX2 (Bruker, 2008); cell
SAINT (Bruker, 2008); data reduction: SAINT (Bruker, 2008); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).Fig. 1. The molecular structure of the title compound. Anisotropic displacement ellipsoids are shown at the 50% probability level. [Symmetry code: (A) 2-x, 1-y, z] |
[Al(C16H14N2O2)(C3H7O)]·0.5CH2Cl2 | F(000) = 3312 |
Mr = 394.82 | Dx = 1.378 Mg m−3 |
Orthorhombic, Fdd2 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: F 2 -2d | Cell parameters from 4106 reflections |
a = 24.427 (3) Å | θ = 2.3–25.6° |
b = 30.875 (4) Å | µ = 0.27 mm−1 |
c = 10.0956 (13) Å | T = 173 K |
V = 7614.0 (16) Å3 | Plate, colourless |
Z = 16 | 0.25 × 0.15 × 0.04 mm |
Bruker SMART APEXII diffractometer | 4069 independent reflections |
Radiation source: fine-focus sealed tube | 3687 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.032 |
ω scans | θmax = 27.0°, θmin = 2.3° |
Absorption correction: multi-scan (SADABS; Bruker, 2008) | h = −31→31 |
Tmin = 0.936, Tmax = 0.989 | k = −39→39 |
13794 measured reflections | l = −12→12 |
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)] = 0.034 | H-atom parameters constrained |
wR(F2) = 0.081 | w = 1/[σ2(Fo2) + (0.0417P)2 + 4.145P] where P = (Fo2 + 2Fc2)/3 |
S = 1.04 | (Δ/σ)max = 0.001 |
4069 reflections | Δρmax = 0.32 e Å−3 |
242 parameters | Δρmin = −0.32 e Å−3 |
1 restraint | Absolute structure: Flack (1983), 1872 Friedel pairs |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: −0.09 (7) |
[Al(C16H14N2O2)(C3H7O)]·0.5CH2Cl2 | V = 7614.0 (16) Å3 |
Mr = 394.82 | Z = 16 |
Orthorhombic, Fdd2 | Mo Kα radiation |
a = 24.427 (3) Å | µ = 0.27 mm−1 |
b = 30.875 (4) Å | T = 173 K |
c = 10.0956 (13) Å | 0.25 × 0.15 × 0.04 mm |
Bruker SMART APEXII diffractometer | 4069 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2008) | 3687 reflections with I > 2σ(I) |
Tmin = 0.936, Tmax = 0.989 | Rint = 0.032 |
13794 measured reflections |
R[F2 > 2σ(F2)] = 0.034 | H-atom parameters constrained |
wR(F2) = 0.081 | Δρmax = 0.32 e Å−3 |
S = 1.04 | Δρmin = −0.32 e Å−3 |
4069 reflections | Absolute structure: Flack (1983), 1872 Friedel pairs |
242 parameters | Absolute structure parameter: −0.09 (7) |
1 restraint |
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 | ||
Al1 | 0.80543 (2) | 0.339391 (17) | 0.48762 (6) | 0.02073 (13) | |
O1 | 0.83307 (5) | 0.32093 (4) | 0.64267 (15) | 0.0274 (3) | |
O2 | 0.74619 (5) | 0.30520 (4) | 0.51299 (14) | 0.0244 (3) | |
O3 | 0.77795 (5) | 0.39121 (4) | 0.50117 (16) | 0.0280 (3) | |
N1 | 0.88207 (6) | 0.35385 (5) | 0.42972 (17) | 0.0233 (4) | |
N2 | 0.80155 (6) | 0.32532 (5) | 0.29380 (17) | 0.0237 (4) | |
C1 | 0.80382 (8) | 0.43157 (6) | 0.5214 (2) | 0.0265 (4) | |
H1A | 0.8401 | 0.4311 | 0.4756 | 0.032* | |
C2 | 0.76904 (10) | 0.46682 (7) | 0.4601 (3) | 0.0408 (6) | |
H2A | 0.7647 | 0.4612 | 0.3651 | 0.061* | |
H2B | 0.7869 | 0.4949 | 0.4730 | 0.061* | |
H2C | 0.7330 | 0.4671 | 0.5025 | 0.061* | |
C3 | 0.81316 (11) | 0.44040 (8) | 0.6673 (3) | 0.0438 (6) | |
H3A | 0.8334 | 0.4162 | 0.7066 | 0.066* | |
H3B | 0.7778 | 0.4435 | 0.7120 | 0.066* | |
H3C | 0.8343 | 0.4672 | 0.6774 | 0.066* | |
C11 | 0.88005 (8) | 0.32767 (6) | 0.7048 (2) | 0.0247 (4) | |
C12 | 0.88427 (9) | 0.31743 (7) | 0.8386 (2) | 0.0332 (5) | |
H12 | 0.8533 | 0.3063 | 0.8842 | 0.040* | |
C13 | 0.93293 (9) | 0.32316 (7) | 0.9064 (3) | 0.0366 (5) | |
H13 | 0.9349 | 0.3161 | 0.9978 | 0.044* | |
C14 | 0.97909 (9) | 0.33922 (7) | 0.8422 (3) | 0.0350 (5) | |
H14 | 1.0125 | 0.3426 | 0.8890 | 0.042* | |
C15 | 0.97586 (9) | 0.35001 (7) | 0.7114 (3) | 0.0328 (5) | |
H15 | 1.0073 | 0.3612 | 0.6678 | 0.039* | |
C16 | 0.92665 (8) | 0.34479 (6) | 0.6396 (2) | 0.0261 (4) | |
C17 | 0.92542 (8) | 0.35630 (6) | 0.5013 (2) | 0.0270 (4) | |
H17 | 0.9583 | 0.3662 | 0.4610 | 0.032* | |
C18 | 0.88543 (8) | 0.36551 (7) | 0.2887 (2) | 0.0275 (5) | |
H18A | 0.9239 | 0.3644 | 0.2578 | 0.033* | |
H18B | 0.8711 | 0.3951 | 0.2742 | 0.033* | |
C21 | 0.70533 (7) | 0.29526 (6) | 0.4337 (2) | 0.0212 (4) | |
C22 | 0.65738 (8) | 0.27644 (6) | 0.4864 (2) | 0.0260 (4) | |
H22 | 0.6560 | 0.2686 | 0.5773 | 0.031* | |
C23 | 0.61261 (8) | 0.26946 (6) | 0.4067 (2) | 0.0304 (5) | |
H23 | 0.5805 | 0.2571 | 0.4442 | 0.036* | |
C24 | 0.61294 (9) | 0.27991 (7) | 0.2725 (2) | 0.0356 (5) | |
H24 | 0.5809 | 0.2767 | 0.2200 | 0.043* | |
C25 | 0.66070 (9) | 0.29500 (7) | 0.2186 (2) | 0.0346 (5) | |
H25 | 0.6622 | 0.3008 | 0.1262 | 0.041* | |
C26 | 0.70752 (8) | 0.30217 (6) | 0.2965 (2) | 0.0270 (4) | |
C27 | 0.75757 (8) | 0.31427 (6) | 0.2327 (2) | 0.0269 (4) | |
H27 | 0.7583 | 0.3141 | 0.1387 | 0.032* | |
C28 | 0.85114 (8) | 0.33286 (7) | 0.2152 (2) | 0.0293 (4) | |
H28A | 0.8413 | 0.3441 | 0.1264 | 0.035* | |
H28B | 0.8717 | 0.3055 | 0.2038 | 0.035* | |
Cl1 | 0.96134 (3) | 0.46418 (3) | 0.61765 (8) | 0.0636 (2) | |
C4 | 1.0000 | 0.5000 | 0.5209 (3) | 0.0304 (7) | |
H4 | 0.9758 | 0.5163 | 0.4650 | 0.036* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Al1 | 0.0173 (2) | 0.0212 (3) | 0.0238 (3) | −0.0013 (2) | 0.0013 (2) | 0.0001 (2) |
O1 | 0.0219 (7) | 0.0353 (8) | 0.0249 (8) | −0.0063 (6) | −0.0031 (6) | 0.0037 (6) |
O2 | 0.0216 (6) | 0.0264 (6) | 0.0252 (8) | −0.0046 (5) | −0.0003 (6) | 0.0029 (6) |
O3 | 0.0210 (6) | 0.0211 (6) | 0.0418 (9) | −0.0013 (5) | 0.0022 (7) | −0.0033 (7) |
N1 | 0.0209 (8) | 0.0223 (8) | 0.0266 (9) | −0.0007 (6) | 0.0031 (7) | 0.0016 (7) |
N2 | 0.0232 (8) | 0.0241 (8) | 0.0238 (9) | −0.0005 (6) | 0.0037 (7) | 0.0019 (7) |
C1 | 0.0222 (9) | 0.0229 (9) | 0.0344 (12) | −0.0023 (7) | 0.0027 (9) | −0.0023 (8) |
C2 | 0.0459 (13) | 0.0263 (10) | 0.0502 (17) | 0.0013 (9) | −0.0088 (12) | −0.0008 (10) |
C3 | 0.0522 (15) | 0.0374 (12) | 0.0416 (15) | −0.0125 (11) | −0.0065 (12) | −0.0009 (11) |
C11 | 0.0232 (9) | 0.0233 (9) | 0.0276 (12) | 0.0007 (8) | −0.0031 (8) | −0.0012 (8) |
C12 | 0.0300 (11) | 0.0373 (12) | 0.0321 (13) | −0.0002 (9) | −0.0016 (9) | 0.0001 (10) |
C13 | 0.0365 (12) | 0.0431 (13) | 0.0301 (13) | 0.0050 (10) | −0.0075 (10) | −0.0040 (10) |
C14 | 0.0272 (11) | 0.0368 (12) | 0.0409 (14) | 0.0030 (9) | −0.0107 (10) | −0.0084 (10) |
C15 | 0.0227 (9) | 0.0293 (10) | 0.0464 (15) | −0.0009 (8) | −0.0030 (9) | −0.0045 (10) |
C16 | 0.0225 (9) | 0.0226 (9) | 0.0332 (12) | 0.0004 (7) | −0.0024 (9) | −0.0028 (8) |
C17 | 0.0200 (9) | 0.0221 (9) | 0.0390 (13) | −0.0003 (7) | 0.0039 (9) | 0.0003 (9) |
C18 | 0.0214 (10) | 0.0280 (10) | 0.0330 (12) | −0.0003 (8) | 0.0063 (9) | 0.0068 (9) |
C21 | 0.0205 (9) | 0.0157 (8) | 0.0275 (10) | 0.0022 (7) | −0.0015 (8) | −0.0005 (7) |
C22 | 0.0271 (10) | 0.0207 (9) | 0.0302 (11) | −0.0002 (7) | 0.0022 (10) | −0.0006 (9) |
C23 | 0.0222 (10) | 0.0257 (10) | 0.0433 (14) | −0.0029 (8) | 0.0033 (10) | −0.0030 (9) |
C24 | 0.0243 (10) | 0.0413 (12) | 0.0411 (14) | −0.0034 (9) | −0.0088 (10) | −0.0027 (10) |
C25 | 0.0309 (11) | 0.0429 (12) | 0.0299 (12) | −0.0047 (9) | −0.0059 (10) | 0.0020 (10) |
C26 | 0.0268 (10) | 0.0268 (10) | 0.0273 (12) | −0.0015 (8) | −0.0016 (9) | −0.0002 (8) |
C27 | 0.0280 (10) | 0.0300 (10) | 0.0228 (11) | −0.0008 (8) | 0.0009 (9) | 0.0001 (9) |
C28 | 0.0272 (10) | 0.0327 (10) | 0.0280 (12) | 0.0020 (8) | 0.0064 (9) | 0.0044 (9) |
Cl1 | 0.0662 (4) | 0.0686 (4) | 0.0559 (5) | −0.0116 (4) | 0.0136 (4) | 0.0262 (4) |
C4 | 0.0347 (16) | 0.0328 (15) | 0.0236 (16) | −0.0003 (12) | 0.000 | 0.000 |
Al1—O3 | 1.7404 (14) | C14—C15 | 1.363 (4) |
Al1—O1 | 1.7974 (15) | C14—H14 | 0.9500 |
Al1—O2 | 1.8094 (14) | C15—C16 | 1.413 (3) |
Al1—N2 | 2.0066 (18) | C15—H15 | 0.9500 |
Al1—N1 | 2.0115 (17) | C16—C17 | 1.442 (3) |
O1—C11 | 1.324 (2) | C17—H17 | 0.9500 |
O2—C21 | 1.315 (2) | C18—C28 | 1.506 (3) |
O3—C1 | 1.412 (2) | C18—H18A | 0.9900 |
N1—C17 | 1.284 (3) | C18—H18B | 0.9900 |
N1—C18 | 1.471 (3) | C21—C26 | 1.403 (3) |
N2—C27 | 1.285 (3) | C21—C22 | 1.412 (3) |
N2—C28 | 1.467 (2) | C22—C23 | 1.375 (3) |
C1—C2 | 1.513 (3) | C22—H22 | 0.9500 |
C1—C3 | 1.515 (3) | C23—C24 | 1.392 (3) |
C1—H1A | 1.0000 | C23—H23 | 0.9500 |
C2—H2A | 0.9800 | C24—C25 | 1.369 (3) |
C2—H2B | 0.9800 | C24—H24 | 0.9500 |
C2—H2C | 0.9800 | C25—C26 | 1.406 (3) |
C3—H3A | 0.9800 | C25—H25 | 0.9500 |
C3—H3B | 0.9800 | C26—C27 | 1.431 (3) |
C3—H3C | 0.9800 | C27—H27 | 0.9500 |
C11—C12 | 1.392 (3) | C28—H28A | 0.9900 |
C11—C16 | 1.417 (3) | C28—H28B | 0.9900 |
C12—C13 | 1.383 (3) | Cl1—C4 | 1.7521 (19) |
C12—H12 | 0.9500 | C4—Cl1i | 1.7520 (19) |
C13—C14 | 1.392 (3) | C4—H4 | 0.9600 |
C13—H13 | 0.9500 | ||
O3—Al1—O1 | 111.59 (8) | C15—C14—H14 | 120.3 |
O3—Al1—O2 | 102.52 (7) | C13—C14—H14 | 120.3 |
O1—Al1—O2 | 89.55 (7) | C14—C15—C16 | 121.2 (2) |
O3—Al1—N2 | 104.92 (8) | C14—C15—H15 | 119.4 |
O1—Al1—N2 | 142.97 (7) | C16—C15—H15 | 119.4 |
O2—Al1—N2 | 88.51 (7) | C15—C16—C11 | 119.2 (2) |
O3—Al1—N1 | 100.24 (7) | C15—C16—C17 | 119.13 (19) |
O1—Al1—N1 | 88.50 (7) | C11—C16—C17 | 121.66 (18) |
O2—Al1—N1 | 156.20 (7) | N1—C17—C16 | 123.21 (18) |
N2—Al1—N1 | 78.96 (7) | N1—C17—H17 | 118.4 |
C11—O1—Al1 | 133.47 (13) | C16—C17—H17 | 118.4 |
C21—O2—Al1 | 131.06 (13) | N1—C18—C28 | 106.40 (16) |
C1—O3—Al1 | 130.54 (12) | N1—C18—H18A | 110.4 |
C17—N1—C18 | 118.95 (17) | C28—C18—H18A | 110.4 |
C17—N1—Al1 | 128.11 (15) | N1—C18—H18B | 110.4 |
C18—N1—Al1 | 112.80 (13) | C28—C18—H18B | 110.4 |
C27—N2—C28 | 118.22 (18) | H18A—C18—H18B | 108.6 |
C27—N2—Al1 | 124.39 (15) | O2—C21—C26 | 122.43 (17) |
C28—N2—Al1 | 117.03 (13) | O2—C21—C22 | 119.78 (18) |
O3—C1—C2 | 108.93 (17) | C26—C21—C22 | 117.78 (18) |
O3—C1—C3 | 111.52 (18) | C23—C22—C21 | 120.3 (2) |
C2—C1—C3 | 110.63 (19) | C23—C22—H22 | 119.9 |
O3—C1—H1A | 108.6 | C21—C22—H22 | 119.9 |
C2—C1—H1A | 108.6 | C22—C23—C24 | 121.9 (2) |
C3—C1—H1A | 108.6 | C22—C23—H23 | 119.0 |
C1—C2—H2A | 109.5 | C24—C23—H23 | 119.0 |
C1—C2—H2B | 109.5 | C25—C24—C23 | 118.1 (2) |
H2A—C2—H2B | 109.5 | C25—C24—H24 | 121.0 |
C1—C2—H2C | 109.5 | C23—C24—H24 | 121.0 |
H2A—C2—H2C | 109.5 | C24—C25—C26 | 121.6 (2) |
H2B—C2—H2C | 109.5 | C24—C25—H25 | 119.2 |
C1—C3—H3A | 109.5 | C26—C25—H25 | 119.2 |
C1—C3—H3B | 109.5 | C21—C26—C25 | 119.85 (19) |
H3A—C3—H3B | 109.5 | C21—C26—C27 | 121.08 (19) |
C1—C3—H3C | 109.5 | C25—C26—C27 | 119.0 (2) |
H3A—C3—H3C | 109.5 | N2—C27—C26 | 124.6 (2) |
H3B—C3—H3C | 109.5 | N2—C27—H27 | 117.7 |
O1—C11—C12 | 119.22 (19) | C26—C27—H27 | 117.7 |
O1—C11—C16 | 122.36 (19) | N2—C28—C18 | 107.38 (17) |
C12—C11—C16 | 118.41 (19) | N2—C28—H28A | 110.2 |
C13—C12—C11 | 121.0 (2) | C18—C28—H28A | 110.2 |
C13—C12—H12 | 119.5 | N2—C28—H28B | 110.2 |
C11—C12—H12 | 119.5 | C18—C28—H28B | 110.2 |
C12—C13—C14 | 120.8 (2) | H28A—C28—H28B | 108.5 |
C12—C13—H13 | 119.6 | Cl1i—C4—Cl1 | 112.20 (18) |
C14—C13—H13 | 119.6 | Cl1i—C4—H4 | 109.3 |
C15—C14—C13 | 119.4 (2) | Cl1—C4—H4 | 109.0 |
Symmetry code: (i) −x+2, −y+1, z. |
D—H···A | D—H | H···A | D···A | D—H···A |
C1—H1A···N1 | 1.00 | 2.64 | 3.204 (3) | 116 |
C18—H18A···O3ii | 0.99 | 2.55 | 3.508 (2) | 163 |
C4—H4···O1iii | 0.96 | 2.33 | 3.2539 (18) | 160 |
Symmetry codes: (ii) x+1/4, −y+3/4, z−1/4; (iii) −x+7/4, y+1/4, z−1/4. |
D—H···A | D—H | H···A | D···A | D—H···A |
C1—H1A···N1 | 1.00 | 2.64 | 3.204 (3) | 115.9 |
C18—H18A···O3i | 0.99 | 2.55 | 3.508 (2) | 163.0 |
C4—H4···O1ii | 0.96 | 2.33 | 3.2539 (18) | 160.4 |
Symmetry codes: (i) x+1/4, −y+3/4, z−1/4; (ii) −x+7/4, y+1/4, z−1/4. |
Acknowledgements
This work was partially supported by the RFBR (12–03–00206_a) and a grant from the President of the Russian Federation to support the research of young Russian scientists and doctors (MD-3634.2012.3).
References
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As a part of our investigation on chemistry of main group elements complexes based on tetradentate ligands (Karlov & Zaitseva, 2001) we obtained and studied the structure of the salen title compound [(salen)AlO-iPr]. The aluminium complex is monomeric (Fig. 1) with a fivefold coordinated Al centre. Its coordination geometry is close to square-based pyramidal with the salen ligand occupying the basal plane and the isopropyloxo group in axial position. It was shown, that the closely related methyloxo compound with an unsubstituted salen ligand [(MeO)(salen)Al]2 is dimeric with two bridging µ2-alkyloxo ligands (Gurian et al. (1991)). In contrast, a similar compound with bulky trimethylphenoxo substituent (2,4,6-Me3C6H2O)(salen)Al exhibited monomeric nature (Atwood et al. (1997)). Also all Al compounds with substituted salen ligands, like widely studied complexes of bulky (tBu)4salen, are monomeric according to CSD data (Allen, 2002), surely due to the steric hindrances. Thus, it may be assumed that the nuclearity of aluminium complexes with an unsubstituted salen ligand depends on the size of the additional alkyloxo group.
The central metal atom is displaced from the basal N,N,O,O plane by 0.4874 (9) Å. Unexpectedly, the Al-O(3)Alk distance (1.7404 (14) Å) is much shorter than Al-OAr bond lengths from the salen ligand (1.7974 (15) and 1.8094 (14) Å). On the other hand, the Al—O(3)—C(1) angle is quite large with 130.54 (12) °. These values indicate the noticeable degree of π- donation from the apical alkyloxo ligand towards the aluminium centre. The same features were previously found in the structure of the closely related monomeric ethyloxo complex (EtO)(salen(tBu)4)Al (Muñoz-Hernandez et al. (2000)).
The isopropyloxo group forms an intramolecular hydrogen bond C1—H1A···N1 with H···N with 2.64 Å and C—H···N 116.0 (1)° that is connected with the mutual ecliptic arrangement of N1—Al1 and O3—C1 bonds.
In the crystal packing, the Al-complexes are linked by weak C18—H18A···O3 hydrogen bonds (C···O 3.508 (2) Å, C—H···O 162.9 (1)°). The asymmetric unit contains a solvent dichlormethane molecule that lies on a crystallographic 2-fold axis and forms C4—H4···O1 hydrogen bonds with C···O separations of 3.2539 (18) Å.