Molecular structure of bis(N-phenylsalicylideneiminato)aluminium-di(μ-isopropoxy)di(isopropoxo) aluminium(III) and its reactions with alkoxyalkanols

Article abstract of DOI:10.1039/b109729f

A novel heterocyclic derivative of aluminium(III) [C₆H₄O{CH=N(C₆H₅)}]₂ Al(μ-OPrⁱ)₂Al(OPrⁱ)₂ 1 has been synthesized by the reaction of aluminium isopropoxide

Full text of DOI:10.1039/b109729f

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Molecular structure of bis(N-phenylsalicylideneiminato)aluminium-
di(ꢀ-isopropoxy)di(isopropoxo)aluminium(III) and its reactions with
alkoxyalkanols†
Nikita Sharma,a Rajnish K. Sharma,a Rakesh Bohra,*a John E. Drake,b
Michael B. Hursthousec and Mark E. Lightc
a Department of Chemistry, University of Rajasthan, Jaipur-302004, India
b Department of Chemistry and Biochemistry, University of Windsor, Windsor, ON N9B 3P4,
Canada
c Department of Chemistry, University of Southampton, Highfield, Southampton,
UK SO17 1BJ
Received 24th October 2001, Accepted 7th February 2002
First published as an Advance Article on the web 26th March 2002
A novel heterocyclic derivative of aluminium() [C H O{CH᎐N(C H )}] Al(µ-OPri) Al(OPri) 1 has been
᎐
6
4
6
5
2
2
2
synthesized by the reaction of aluminium isopropoxide with N-phenylsalicylidene imine in 1 : 1 molar ratio in
refluxing anhydrous benzene. Reactions of 1 with alkoxyalkanols in 1 : 1 and 1 : 2 molar ratios in refluxing anhydrous
benzene yielded binuclear complexes of the types, [C H O{CH᎐N(C H )}] Al(µ-OPri) Al(OCH CH OR)(OPri) and
᎐
6
4
6
5
2
2
2
2
[C H O{CH᎐N(C H )}] Al(µ-OPri) Al(OCH CH OR) (where R᎐CH , C H and C H ), respectively. All of these
n
᎐
᎐
6
4
6
5
2
2
2
2
2
3
2
5
4
9
binuclear complexes have been characterized by elemental analysis, molecular weight measurements, and spectral
studies. The FAB mass spectrum and 27Al NMR spectrum of 1 indicate that it is a discrete unsymmetrical dimer
containing four- and six-coordinated aluminium() atoms as confirmed by its single crystal X-ray structure.
Introduction
Results and discussion
The role of metal alkoxides as precursors to metal oxide
materials by sol–gel processing or metal organic chemical
vapour deposition (MOCVD) has given new impetus to inten-
sive investigations of the synthesis of heteroleptic derivatives in
which the labile alkoxy ligands are replaced by chelating/
sterically demanding ligands1,2 such as β-diketones,3,4 glyco-
late,5,6 acetate,7 or alkanolaminate.8–10 These ligands have played
a significant role in modifying the solubility and reactivity of
the resulting alkoxide derivatives to make them suitable pre-
cursors for high-purity metal oxide-based ceramic materials.
The complex [Al(OR)2(acac)]n is a monomer when R = SiPh3
and a discrete unsymmetrical binuclear, [(acac)2Al(µ-OPri)2-
Al(OPri)2], when R = Pri, due to the presence of comparatively
stable four- and six-coordinated aluminium() atoms.11 The
replacement of the two terminal isopropoxy groups with
ligands such as glycols,12,13 thioglycols,14 8-hydroxyquinoline15
or oximes16 is quite facile, leading to products containing the
same unsymmetrical structures. Recently we reported that steric
and electronic factors play a very important role in aluminium
(alkoxide) β-diketonate chemistry.15–18 In continuation of our
studies on the synthesis and structural elucidations of some
novel heterocyclic compounds containing aluminium() atoms
in different coordination environments, we report herein the
A novel heteroleptic species, bis(N-phenylsalicylideneiminato)-
aluminium-di-µ-isopropoxo-di-isopropoxoaluminium(), has
been prepared by the reaction of aluminium isopropoxide
and N-phenylsalicylidene imine in 1 : 1 molar ratio in refluxing
anhydrous benzene as shown in eqn. (1):
Al(OPri) ϩ C H (OH)CH᎐NC H
᎐
3
6
4
6
5
1/2[C H O{CH᎐N(C H )}] Al(µ-OPri) Al(OPri)
᎐
6
4
6
5
2
2
2
1 ϩ PriOH (1)
This reaction is quite facile and quantitative and its progress
was followed by estimating the isopropanol liberated azeo-
tropically. The complex 1 is a lemon coloured crystalline solid
that is soluble in common organic solvents.
Reactions of 1 with alkoxyalkanols in 1 : 1 and 1 : 2 molar
ratios in refluxing anhydrous benzene solution yield the desired
products:
(2)
chemistry of a new heteroleptic precursor, [C H O{CH᎐
᎐
6
4
N(C6H5)}]2Al(µ-OPri)2Al(OPri)2.
† Synthesis and structural elucidations of some novel heterocyclic
compounds containing aluminium() atoms at bridge-head positions.
Part 2.32
Electronic supplementary information (ESI) available: mass spec-
trum assignments, IR, 1H NMR and 13C NMR spectral data. See http://
www.rsc.org/suppdata/dt/b1/b109729f/
All of these reactions are quantitative and the liberated iso-
propanol could be removed readily in 4 hours. Their com-
pletion was checked by estimating the isopropanol liberated
azeotropically. All the products are yellow coloured foamy
solids and are soluble in common organic solvents. Molecular
DOI: 10.1039/b109729f
J. Chem. Soc., Dalton Trans., 2002, 1631–1634
This journal is © The Royal Society of Chemistry 2002
1631

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Table 1 Synthetic and analytical data for [C6H4O{CH᎐N(C6H5)}]2Al(µ-OPri)2Al(OCH2CH2OR)(OPri) and [C6H4O{CH᎐N(C6H5)}]2Al(µ-OPri)2-
᎐
᎐
Al(OCH2CH2OR)2
Elemental analysis (%)
Molar mPr OH b/g
Yield
Melting Mol. Wt.
Point/ЊC Found (calc.)
i
m[C H O{CH᎐
6
4
᎐
Entry
a/g
mHOCH CH OR a/g
ratio found (calc.) (%)
Al
OPri
N(C6H5)}Al(OPri)2]2
2
2
1.
2.
3.
4.
5.
6.
7.
4.18 [Al(OPri)3]
4.08 [C6H4(OH)CH᎐NC6H5]
1 : 1
1 : 1
1 : 2
1 : 1
1 : 2
1 : 1
1 : 2
1.21 (1.23)
0.18 (0.18)
0.42 (0.44)
0.16 (0.18)
0.34 (0.38)
0.16 (0.18)
0.45 (0.48)
98.7 7.4 (7.90)
98.9 7.24 (7.72) 25.2 (25.30)
97.5 7.33 (7.55) 16.41 (16.53) 180
98.9 7.44 (7.57) 24.57 (24.84) Viscous 695 (712.78)
98.2 7.00 (7.21) 15.01 (15.89) Viscous 730 (742.58)
34.01 (34.56) 142
674 (682.78)
701 (698.68)
760 (714.58)
᎐
2.08
2.52
2.08
2.14
2.02
2.78
0.28 (R = CH3)
0.56 (R = CH3)
0.29 (R = C2H5)
0.58 (R = C2H5)
0.36 (R = C4H9)
0.96 (R = C4H9)
158
99.2 7.16 (7.29) 23.39 (23.9)
98
728 (740.68)
96.0 6.36 (6.76) 14.32 (14.78) Viscous 776 (798.58)
a Except where reagents are otherwise specified (entry 1). b Liberated during reaction.
weight determinations indicate the binuclear nature of these
complexes in refluxing benzene (Table 1).
methine protons, correspond to bridging isopropoxy groups
only. A multiplet in the δ 6.27–7.92 ppm region can be assigned
to the aromatic protons of N-phenylsalicylideneimine. No
appreciable shift was observed in the position of alkoxyalkanol
protons which were observed at their expected positions, ruling
out the possibility of the coordination through the oxygen atom
of the alkoxyalkanol moiety (see ESI, Table S3†).
FAB Mass spectra
The FAB mass spectral data also indicate the binuclear form
of 1 (see ESI, Table S1†).
IR Spectra
13C NMR Spectra
The IR spectra of the complexes were interpreted by comparing
the spectra with that of the free ligands. A medium intensity
band at 3300 cmϪ1 in the free ligands due to ν(OH) is absent in
the IR spectra of the complexes, indicating deprotonation of
the N-phenylsalicylideneimine as well as the alkoxyalkanol.
This is further supported by the appearance of a new band in
the region 685–630cmϪ1 assigned to ν(Al–O).19 A strong band is
observed in the free Schiff base, N-phenylsalicylideneimine, at
The 13C NMR chemical shifts provide further evidence of the
presence of coordinated Schiff base in these aluminium()
complexes. The azomethine carbon is deshielded and two
signals appears at δ 161.1–167.5 and 162.1–170.2 ppm. This
deshielding as well as the presence of two carbon signals again
support coordination through the azomethine nitrogen to the
aluminium atom and the nonequivalent nature of azomethine
carbon, which is substantiated by the X-ray structure of
complex 1. The aromatic carbon signals of N-phenylsalicyl-
ideneimine appear in the range δ 115.2–151.0 ppm. Further, the
presence of two carbon signals each for methyl (δ 23.9–25.1
ppm) and methine (δ 62.1–67.8 ppm) of the isopropoxy groups
in compounds 1, 2, 4 and 6, indicate the nonequivalent nature
of bridging and terminal isopropoxy groups. Only one carbon
signal each for methyl (δ 25.2–25.7) and methine (δ 63.9–64.3
ppm) appear for compounds 3, 5 and 7 which correspond to
bridging isopropoxy groups. The positions and number of
alkoxyalkanol carbon signals are as expected. The fact that no
significant shift was observed in the position of alkoxy carbon
of these ligand moieties further suggest that the alkoxyalkanol
moieties bind to aluminium atom in a monodentate fashion.
(see ESI, Table S4†).
1625 cmϪ1, characteristic of the azomethine (>C᎐N) group.20
᎐
Coordination of N-phenylsalicylidene imine to aluminium
through the azomethine nitrogen atom is expected to reduce the
electron density in the azomethine link and lower the ν(C᎐N)
᎐
absorption frequency. In the spectra of all the new complexes,
the band due to ν(C᎐N) appears at lower wavenumber, 1625–
᎐
1610 cmϪ1, indicating coordination of the azomethine nitrogen
to the aluminium atom.21 This is further supported by the
appearance of a new band at 610–550 cmϪ1 assigned to ν(Al–
N).19 The absorption frequency of phenolic C–O at 1310–1260
cmϪ1 in the aluminium complexes (1260 cmϪ1 in the free ligand),
indicates that the other coordinating site of the Schiff base
is through phenolic oxygen.21,22 A medium intensity band
observed at 1010–995 cmϪ1 may be assigned to ν(C–O) of the
isopropoxy group. The Al–O–Al vibrations are observed in the
region 760–745 cmϪ1 (see ESI, Table S2†).
27Al NMR Spectra
1H NMR Spectra
27Al NMR spectrum of compound 1, at room temperature,
exhibits two signals (δ 7.8 and 40.1 ppm) indicating the presence
of both 6- and 4-coordination around aluminium() atoms,
respectively.16
1
The H NMR spectra of 1 and its alkoxyalkanol derivatives
exhibit characteristic peaks. The phenolic group resonance
present in the free Schiff base (N-phenylsalicylideneimine) is
absent in the 1H NMR spectra of 1 as well as all the complexes,
indicating deprotonation of the OH group and formation of
the Al–O bond. The presence of a doublet at δ 8.16–8.62 ppm
for the azomethine protons signal of the N-phenylsalicylidene-
imine group in the spectra of all of these complexes, indicates the
nonequivalent nature of the azomethine protons. These signals
aredownfieldcomparedtothefreeligand,suggestingdeshielding
of the azomethine protons due to coordination to aluminium
through the azomethine nitrogen. Similarly, the presence of two
doublets (δ 1.03–1.17 and 1.18–1.28 ppm) and two multiplets
(δ 3.41–3.68 and 3.99–4.08 ppm) for methyl and methine pro-
tons, respectively, of the bridging and terminal isopropoxy
groups (for compounds 1, 2, 4 and 6), indicate the inequivalent
nature of the bridging and terminal isopropoxy groups, how-
ever, for compounds 3, 5 and 7, the presence of one doublet at
δ 1.18 ppm and one multiplet at δ 3.90–4.02 ppm for methyl and
27Al NMR spectrum of a representative compound, [C6-
H O{CH᎐N(C H )}] Al(µ-OPri) Al(OCH CH OC H )(OPri)
᎐
4
6
5
2
2
2
2
2
5
at room temperature also exhibits two signals (δ 9.08 and
43.8 ppm) suggesting the presence of 6- and 4-coordinated
aluminium() atoms.
In view of the binuclear nature of the above products 2–7 as
well as the monodentate behaviour of the alkoxyalkanol ligand
moieties as indicated by the above studies, the following tent-
ative structure may be proposed for these derivatives (Fig. 1).
Crystal structure of [C H O{CH᎐N(C H )}] Al(ꢀ-OPri) -
᎐
6
4
6
5
2
2
Al(OPri)2 1
A single-crystal X-ray diffraction study of [C H O{CH᎐
᎐
6
4
N(C6H5)}]2Al(µ-OPri)2Al(OPri)2 1 shows that the unsymmet-
rical binuclear structure contains tetra- and hexa-coordinated
aluminium (Fig. 2). The hexa-coordinated aluminium is bound
1632
J. Chem. Soc., Dalton Trans., 2002, 1631–1634

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in toluene using aluminium nitrate as an external reference
in aqueous solution. Molecular weight measurements were
carried out by the elevation in boiling point method using a
Beckmann thermometer (Einstellthermometer n-Beckmann,
Labortherm-N, Skalenwert, 0.01K, made in GDR) fitted in
a glass assembly (supplied by JSGW, India) in anhydrous
benzene. All manipulations were carried out under anhydrous
conditions using anhydrous CaCl2 guard/side tubes. FAB mass
spectra were recorded on a JEOL SX 102/DA-6000 mass
spectrometer/data system using argon/xenon (6 kV, 10 mA) as
the FAB gas and m-nitrobenzyl alcohol as the matrix.
Fig. 1 Proposed structure of [C6H4O{CH᎐NC6H5}]2Al(µ-OPri)2Al-
᎐
n
(OCH2CH2OR)n(OPri)2 Ϫ n (R = CH3, C2H5 and C4H9 ; n = 1 or 2).
Preparation of [C H O{CH᎐N(C H )}] Al(ꢀ-OPri) Al(OPri) 1
᎐
6
4
6
5
2
2
2
To a benzene solution (∼30 mL) of aluminium isopropoxide
(4.18 g) was added C H (OH)CH᎐NC H (4.07 g) in benzene
᎐
6
4
6
5
(30 mL). The contents were refluxed for 4 h and the progress of
the reaction was monitored by the determination of isoprop-
anol liberated azeotropically with benzene. A yellow, clear sol-
ution was obtained. After the removal of the solvent under
reduced pressure, a yellow solid was obtained. A concentrated
solution of the complex in benzene at room temperature gave
yellow crystals (98.7% yield; mp. 142 ЊC).
Reactions of 1 with alkoxyalkanols in 1 : 1 and 1 : 2 molar
ratios in refluxing anhydrous benzene gave binuclear complexes
of the type [C H O{CH᎐N(C H )}] Al(µ-OPri) Al(OCH CH -
᎐
6
4
6
5
2
2
2
2
n
OR)n(OPri)2
(R = CH3, C2H5, C4H9 ; n = 1 or 2). Since all
Ϫ
n
of these compounds were synthesized by a similar route, the
synthesis of only one representative compound is described in
detail below.
Synthesis of [C H O{CH᎐N(C H )}] Al(ꢀ-OPri) Al-
᎐
6
4
6
5
2
2
(OCH2CH2OCH3)(OPri)
Methoxyethanol (0.23 g) was added to a benzene solution (∼40
mL) of 1. (2.08 g) and the reaction mixture was refluxed on a
fractionating column for 4 h. The isopropanol in the reaction
was collected azeotropically with benzene. The progress as well
as the completion of the reaction was checked by the estimation
of the liberated isopropanol in the azeotrope by an oxidimetric
method. A yellow, clear solution was obtained. After stripping
off the excess solvent under reduced pressure, a shiny-yellow
foamy solid was obtained in quantitative yield which was
recrystallized from a 7 : 1 mixture of dichloromethane and
n-hexane. Syntheses of the other derivatives and analytical data
are summarized in Table 1.
Fig. 2 ORTEP plot31 of the molecule [C6H4O{CH᎐N(C6H5)}]2Al(µ-
᎐
OPri)2Al(OPri)2. The atoms are drawn with 25% probability ellipsoids.
Hydrogen atoms are omitted for clarity.
to two N-phenylsalicylideneimine chelate moieties, the tetra-
coordinated aluminium is bound to two terminal isopropoxide
ligands, and bridging isopropoxide groups join the metal cen-
ters. The Al–O bond lengths (Table 3) involving the isoprop-
oxide groups fall into three categories: (i) 1.932(3)–1.909(3) Å
found in the bridging isopropoxy groups bound to the hexa-
coordinated aluminium sites, (ii) 1.792(3)–1.799(3) Å found in
the same bridging isopropoxy groups bound to the tetra-
coordinated aluminium sites and (iii) 1.704(3)–1.685(3) Å
found in the terminal isopropoxy groups which occupy tetra-
coordinated positions. For the bridging isopropoxy group, the
Al–O bond length involving the hexa-coordinated aluminium
atom is greater than that involving the tetra-coordinated
aluminium atom, arising from the steric crowding imposed by
the neighbouring salicylidene imine ligand. Both the Al–O
bond lengths to salicylideneimine are essentially the same as are
those for Al–N.
X-Ray diffraction analysis
A pale yellow block crystal of [C H O{CH᎐N(C H )}] Al-
᎐
6
4
6
5
2
(µ-OPri)2Al(OPri)2ؒ0.5C6H6 was mounted on a glass fibre. Data
was collected on an Enraf Nonius KappaCCD area detector (ꢀ
and ω scans chosen to give a complete asymmetric unit) at the
University of Southampton EPSRC National Crystallography
Service. Data collection and cell refinement26 gave cell con-
stants corresponding to a triclinic cell whose dimensions are
given in Table 2 along with other experimental parameters. An
absorption correction was applied.27
The structure was solved by direct methods,28 and the struc-
ture was refined using the WinGX version29 of SHELX-97.30
All of the non-hydrogen atoms were treated anisotropically. All
hydrogen atoms were included in idealized positions with C–H
set at 0.95 Å and with isotropic thermal parameters set at 1.2
times that of the carbon atom to which they were attached. The
thermal paramaters are relatively large for the carbon atoms of
the isopropyl groups, particularly and not surprisingly, for
those in the terminal positions. However, attempts to model
the disorder gave no significant improvement to refinement.
Selected bond distances and bond angles are given in Table 3.
The complete molecule is displayed in the ORTEP diagram in
Fig. 2.
Experimental
All manipulations were carried out under anhydrous con-
ditions. Solvents were purified and dried according to standard
procedures.23 The Schiff base, N-phenylsalicylideneimine, was
prepared according to a published procedure.24 Aluminium16
and isopropanol25 were estimated as reported earlier.
Infrared spectra were recorded as Nujol mulls on a Nicolet
Magna 550 spectrophotometer in the range 4000–400 cmϪ1. 1H
and 13C NMR spectra were recorded on a JEOL FX90Q
spectrometer using TMS as an internal reference in CDCl3 and
CHCl3, respectively. 27Al NMR spectral study was carried out
J. Chem. Soc., Dalton Trans., 2002, 1631–1634
1633

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Table 2 Crystal data and structure refinement for [C6H4O{CH᎐
a Project fellowship. M. B. H. thanks the UK Engineering
and Physical Sciences Council for support of the X-ray
facilities at Southampton. J. E. D. thanks the Natural Sciences
and Engineering Research Council of Canada for financial
support.
᎐
N(C6H5)}]2Al(OPri)2Al(OPri)2
Empirical formula
Formula weight
C41H51N2O6Al2
721.80
Temperature/ЊC
Ϫ120(2)
Wavelength/Å
Crystal system
Space group
0.71073
Triclinic
¯
P1
References
a/Å
b/Å
9.701(2)
10.291(2)
1 L. G. Hubert-Pfalzgraf, Coord. Chem. Rev., 1998, 178, 967.
2 W. A. Herrman, N. W. Huber and O. Runte, Angew. Chem., Int. Ed.
Engl., 1995, 34, 2187.
3 L. R. Sita, R. Xi, G. P. A. Yap, L. M. Liable-Sands and A. L.
Rheingold, J. Am. Chem. Soc., 1997, 119, 756.
4 S. Parola, R. Papiernik, L. G. Hubert-Pfalzgraf, S. Jagner and
M. Hakansson, J. Chem. Soc., Dalton Trans., 1997, 4631.
5 L. B. Archer, M. J. H. Smith and E. N. Duester, Polyhedron, 1996,
15, 929.
6 G. J. Gainsford, T. Kemmit and N. B. Milestone, Inorg. Chem., 1995,
34, 5244.
7 V. G. Kessler, L. G. Hubert-Pfalzgraf, S. Halut and J. C. Daran,
J. Chem. Soc. Chem. Commun., 1994, 705.
8 O. Yu. Vassilyeva, V. N. Kokozay, N. A. Zhukova and L. A.
Kovbasyuk, Polyhedron, 1997, 16, 263.
9 R. R. Schrock, Acc. Chem. Res., 1997, 30, 9.
10 O. M. Falana, H. F. Koch, D. M. Roundhill, G. J. Lumetta and
B. P. Hay, Chem. Commun., 1998, 503.
11 J. H. Wengrovius, M. F. Garbauskas, E. A. Williams, R. C. Going,
P. E. Donahue and J. F. Smith, J. Am. Chem. Soc., 1986, 108,
982.
c/Å
α/Њ
β/Њ
21.301(4)
102.51(3)
91.21(3)
108.88(3)
1954.7(7)
2
1.226
0.122
γ/Њ
V/ÅϪ3
Z
Dc/g cmϪ3
µ/mmϪ1
F(000)
770
Crystal size/mm
θ range for data collection/Њ
Limiting indices
0.25 × 0.15 × 0.10
3.02 to 25.03
Ϫ11 р h р 11, Ϫ12 р k р 12,
Ϫ25 р l р 25
18969
5873 [Rint = 0.1010]
(3667 for F 2 > 4σ(F 2)
0.9879 and 0.9701
Full-matrix least squares on F 2
5873/0/481
Reflections collected
Independent reflections
Max. and min. transmissions
Refinement method
Data/restraints/parameters
Goodness-of-fit on F 2
Final R indices [F 2 > 4σ(F 2)]
R indices (all data)
1.040
R1 = 0.0669, wR2 = 0.1598
R1 = 0.1204, wR2 = 0.1865
0.002(2)
12 A. Dhammani, R. Bohra and R. C. Mehrotra, Polyhedron, 1995, 14,
733.
Extinction
Largest diff. peak and hole/e ÅϪ3
0.505 and Ϫ0.449
13 A. Dhammani, R. Bohra and R. C. Mehrotra, Main Group Met.
Chem., 1995, 18, 687.
14 A. Dhammani, R. Bohra and R. C. Mehrotra, Polyhedron, 1996, 15,
733.
Table 3 Selected bond lengths [Å] and angles [Њ] for [C6H4O{CH᎐N-
᎐
15 A. Dhammani, R. Bohra and R. C. Mehrotra, Polyhedron, 1998, 17,
(C6H5)}]2Al{O(i-Pr)}2Al{O(i-Pr)}2
163.
16 Nikita Sharma, Rajnish K. Sharma and Rakesh Bohra, Main Group
Met. Chem., 2001, 24, 781.
17 R. Bohra, A. Dhammani, R. K. Sharma and R. C. Mehrotra, Synth.
React. Inorg. Met.-Org. Chem., 2001, 31, 681.
18 S. Nagar, A. Dhammani, R. Bohra and R. C. Bohra, J. Coord.
Chem., 2002, in press.
Al(1)–O(1)
Al(1)–O(3)
Al(1)–N(1)
Al(2)–O(3)
Al(2)–O(5)
Al(1)––Al(2)
1.813(3)
1.932(3)
2.079(3)
1.792(3)
1.704(3)
2.887(2)
Al(1)–O(2)
Al(1)–O(4)
Al(1)–N(2)
Al(2)–O(4)
Al(2)–O(6)
1.818(3)
1.909(3)
2.075(3)
1.799(3)
1.685(3)
19 A. Singh, A. K. Rai and R. C. Mehrotra, Indian J. Chem., 1973, 11,
478.
O(3)–Al(1)–O(4)
O(1)–Al(1)–O(4)
O(1)–Al(1)–O(3)
O(1)–Al(1)–N(1)
O(2)–Al(1)–N(1)
O(4)–Al(1)–N(1)
O(3)–Al(1)–N(1)
N(1)–Al(1)–N(2)
O(3)–Al(2)–O(4)
O(3)–Al(2)–O(5)
O(4)–Al(2)–O(5)
Al(1)–O(3)–Al(2)
Al(1)–O(1)–C(1)
C(7)–N(1)–Al(1)
74.9(1)
167.1(1)
92.2(1)
89.5(1)
83.8(1)
92.9(1)
95.6(1)
169.4(1)
81.2(1)
109.9(1)
115.6(1)
101.6(1)
134.5(2)
123.6(3)
O(1)–Al(1)–O(2)
O(2)–Al(1)–O(3)
O(2)–Al(1)–O(4)
O(1)–Al(1)–N(2)
O(2)–Al(1)–N(2)
O(4)–Al(1)–N(2)
O(3)–Al(1)–N(2)
99.8(1)
168.0(1)
93.1(1)
84.3(1)
88.7(1)
95.1(1)
93.2(1)
20 B. Khera, A. K. Sharma and N. K. Kaushik, Polyhedron, 1983, 2,
1177.
21 N. Dharmaraj, P. Viswanathamurthi and K. Natarajan, Transition
Met. Chem., 2001, 26, 105.
22 R. Ramesh, P. K. Suganthy and K. Natarajan, Synth. React. Inorg.
Met.-Org. Chem., 1996, 26, 47.
23 Anita Dhammani, Ph. D. Thesis, 1996 University of Rajasthan,
Jaipur.
24 R. H. Holm, G. W. Everett and A. Chakravorty, Prog. Inorg. Chem.,
1966, 7, 83.
25 D. C. Bradley, F. M. A. Halim and W. Wardlaw, J. Chem. Soc., 1950,
3450.
O(5)–Al(2)–O(6)
O(3)–Al(2)–O(6)
O(4)–Al(2)–O(6)
Al(1)–O(4)–Al(2)
Al(1)–O(2)–C(14)
C(20)–N(2)–Al(1)
116.4(2)
118.5(1)
110.5(2)
102.2(1)
135.6(2)
124.4(3)
26 Denzo: Z. Otwinowski and W. Minor, Methods Enzymol., 1997, 206,
307.
27 SORTAV: R. H. Blessing, Acta Crystallogr., Sect. A, 1995, 51, 33;
R. H. Blessing, J Appl. Crystallogr, 1997, 30, 421.
28 G. M. Sheldrick, Acta Crystallogr., Sect. A, 1990, 46, 467.
29 L. J. Farrugia, J. Appl. Crystallogr., 1999, 32, 837.
30 SHELXL-97: G. M. Sheldrick, University of Göttingen, Germany,
1997.
31 C. K. Johnson, ORTEP, Report ORNL-5138, Oak Ridge National
Laboratory, Oak Ridge, TN, 1996.
32 Part 1: N. Sharma, R. K. Sharma and R. Bohra, Main Group Met.
Chem., 2001, 24, 781.
CCDC reference number 171510.
See http://www.rsc.org/suppdata/dt/b1/b109729f/ for crystal-
lographic data in CIF or other electronic format.
Acknowledgements
We are grateful to UGC, DST (New Delhi) and DAE(Mumbai)
for financial support. One of us (N. S.) is grateful to UGC for
1634
J. Chem. Soc., Dalton Trans., 2002, 1631–1634