Epoxide ring opening in a zinc(II) complex in water without any Lewis acid catalyst: Formation of only one diastereomer out of 23

Article abstract of DOI:10.1016/j.ica.2011.04.037

The epoxide ring in 5,6-dihydro-5,6-epoxy-1,10-phenanthroline (L) opens up in its reaction with 4-methylaniline and 4-methoxyaniline in water in equimolar proportion at room temperature without any Lewis acid catalyst to give a monohydrate of 6-(4-methyl-phenylamino)-5,6-dihydro-1,10-phenanthrolin-5-ol (L′·H₂O) and 6-(4-methoxyphenyl-amino)-5,6-dihydro-1,10- phenanthrolin-5-ol (L″) respectively. Reaction time decreases from 72 to 14 h in boiling water. But the yields become less. Reaction of L with Zn(ClO₄)₂·6H₂O in methanol in 3:1 molar ratio at room temperature affords white [ZnL₃](ClO₄) ₂·H₂O. The X-ray crystal structure of the acetonitrile solvate [ZnL₃](ClO₄)₂·MeCN has been determined which shows that the metal has a distorted octahedral N ₆ coordination sphere. [ZnL₃](ClO₄) ₂·2H₂O reacts with 4-methylaniline and 4-methoxyaniline in boiling water in 1:3 molar proportion in the absence of any Lewis acid catalyst to produce [ZnL′₃](ClO₄) ₂·4H₂O and [ZnL″₃](ClO ₄)₂·H₂O, respectively in 1-4 h time in somewhat low yield. In the ¹H NMR spectra of [ZnL′₃] (ClO₄)₂·4H₂O and [ZnL″ ₃](ClO₄)₂·H₂O, only one sharp methyl signal is observed implicating that only one diastereomer out of the 2³ possibilities is formed. The same diastereomers are obtained when L′·H₂O and L″ are reacted directly with Zn(ClO₄)₂·6H₂O in tetrahydrofuran at room temperature in very good yields. Reactions of L′·H ₂O and L″ with Ru(phen)₂Cl₂· 2H₂O (phen = 1,10-phenanthroline) in equimolar proportion in methanol-water mixture under refluxing condition lead to the isolation of two diastereomers of [Ru(phen)₂L′](ClO₄) ₂·2H₂O and [Ru(phen)₂L″](ClO ₄)₂·2H₂O.

Full text of DOI:10.1016/j.ica.2011.04.037

Inorganica Chimica Acta 375 (2011) 101–105
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Epoxide ring opening in a zinc(II) complex in water without any Lewis acid catalyst:
Formation of only one diastereomer out of 23
Nirmal K. Shee a, F.A. Oluwafunmilayo Adekunle a,1, Debashree Das a, Michael G.B. Drew b, Dipankar Datta a,
⇑
a Department of Inorganic Chemistry, Indian Association for the Cultivation of Science, Calcutta 700 032, India
b Department of Chemistry, University of Reading, Whiteknights, Reading RG6 6AD, UK
a r t i c l e i n f o
a b s t r a c t
Article history:
The epoxide ring in 5,6-dihydro-5,6-epoxy-1,10-phenanthroline (L) opens up in its reaction with 4-
methylaniline and 4-methoxyaniline in water in equimolar proportion at room temperature without
any Lewis acid catalyst to give a monohydrate of 6-(4-methyl-phenylamino)-5,6-dihydro-1,10-phen-
anthrolin-5-ol (L0ꢀH2O) and 6-(4-methoxyphenyl-amino)-5,6-dihydro-1,10-phenanthrolin-5-ol (L00)
respectively. Reaction time decreases from 72 to 14 h in boiling water. But the yields become less. Reac-
tion of L with Zn(ClO4)2ꢀ6H2O in methanol in 3:1 molar ratio at room temperature affords white
[ZnL3](ClO4)2ꢀH2O. The X-ray crystal structure of the acetonitrile solvate [ZnL3](ClO4)2ꢀMeCN has been
Received 4 November 2010
Received in revised form 19 April 2011
Accepted 20 April 2011
Available online 27 April 2011
Keywords:
Zinc(II)
Epoxide
Epoxide opening
Diastereomer
Diastereoselective
determined which shows that the metal has
a distorted octahedral N6 coordination sphere.
[ZnL3](ClO4)2ꢀ2H2O reacts with 4-methylaniline and 4-methoxyaniline in boiling water in 1:3 molar pro-
portion in the absence of any Lewis acid catalyst to produce [ZnL03](ClO4)2ꢀ4H2O and [ZnL003](ClO4)2ꢀH2O,
1
respectively in 1–4 h time in somewhat low yield. In the H NMR spectra of [ZnL03](ClO4)2ꢀ4H2O and
[ZnL003](ClO4)2ꢀH2O, only one sharp methyl signal is observed implicating that only one diastereomer
out of the 23 possibilities is formed. The same diastereomers are obtained when L0ꢀH2O and L00 are reacted
directly with Zn(ClO4)2ꢀ6H2O in tetrahydrofuran at room temperature in very good yields. Reactions of
L0ꢀH2O and L00 with Ru(phen)2Cl2ꢀ2H2O (phen = 1,10-phenanthroline) in equimolar proportion in metha-
nol–water mixture under refluxing condition lead to the isolation of two diastereomers of [Ru(phen)2L0]-
(ClO4)2ꢀ2H2O and [Ru(phen)2L00](ClO4)2ꢀ2H2O.
Ó 2011 Elsevier B.V. All rights reserved.
1. Introduction
a-amino acid ester proceeds smoothly in refluxing trifluoroethanol
[3]. The same reactions fail in water. In contrast, aliphatic and aro-
matic amines are found to cleave an epoxide ring in water at room
temperature without any Lewis acid catalyst [4]. Herein we report
opening of an epoxide group present in a chelate ring of a metal
complex by aromatic amines stoichiometrically in refluxing water
in the absence of any catalyst. The ligand chosen is 5,6-dihydro-
5,6-epoxy-1,10-phenanthroline (L) and the metal ion is Zn(II).
Epoxides (or oxiranes) are highly versatile intermediates in syn-
thetic organic chemistry. Nature also uses them as intermediates in
many key biosynthetic pathways. However, there are other func-
tions of epoxides in biological systems. They can impart localised
structural rigidity, confer cytotoxicity by alkylation, or be second-
ary metabolites [1]. The chemistry of epoxides is dominated by the
reactions that involve opening of the strained three-membered
heterocyclic ring by nucleophiles. Such reactions yield valuable
bifunctional compounds. In nature, epoxide ring opening is cata-
lysed by the phenolic proton of a tyrosine moiety [2]. But in labo-
ratory, the cleavage usually occurs in non-aqueous media in
presence of a Lewis acid catalyst like Al2O3, Li+, Mg2+, etc. Addition-
ally often elevated temperature and excess of nucleophiles are
required. There are a few reports where use of a catalyst has not
been necessary [3,4]. For example, aminolysis of epoxide by an
2. Results and discussion
Stirring of L with 4-methylaniline and 4-methoxyaniline in
equimolar proportion in water at room temperature for 72 h with-
out any Lewis acid catalyst gives L0ꢀH2O and L00, respectively
(Scheme 1). The yield of L0ꢀH2O is 90% and that of L00 70%. These
are obtained in 60% yield when the reactants are refluxed in water
for 14 h. But the yield goes on decreasing when increasingly more
refluxing time is used. Earlier Moody et al. have [5] studied open-
ing of the epoxide ring in L in connection with their total synthesis
of the pentacyclic marine alkaloid ascididemin from 1,10-phenan-
throline (phen). They used reaction (1) in dichloromethane to ob-
tain L00 in 74% yield. However, unsubstituted aniline can open the
⇑
Corresponding author. Tel.: +91 33 2473 5374; fax: +91 33 2473 2805.
E-mail address: icdd@iacs.res.in (D. Datta).
1
Permanent address: Department of Pure and Applied Chemistry, Ladoke Akintola
University of Technology, P.M.B. 4000, Ogbomoso, Nigeria.
0020-1693/$ - see front matter Ó 2011 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2011.04.037

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N.K. Shee et al. / Inorganica Chimica Acta 375 (2011) 101–105
atom has a distorted octahedral N6 coordination sphere. The main
cause of distortion is the bite angles of the ligand which are
N
N
N
N
OH
77.45(13), 76.74(14) and 76.67(14)°. The Zn–N bond lengths show
0
O
H N
X
+
2
some variations in the range of 2.147(3)–2.202(4) ÅA. A similar var-
N
H
X
iation is found in the structure of [Zn(phen)3](ClO4)2 of 2.122–
0
2.230 ÅA [8]. As is apparent from Fig. 1, two oxygen atoms O(38),
O(58) are directed in one direction and O(18) the other, thus the
structure of [ZnL3]2+ lacks C3 symmetry. Our DFT calculations at
the B3LYP/6-311⁄⁄ level show that the symmetric structure is more
stable than that found in X-ray crystallography by only
L
L': X = Me; L'': X = OMe
Scheme 1.
0.2 kJ molꢁ1
.
[ZnL3](ClO4)2ꢀ2H2O reacts with 4-methylaniline and 4-
methoxyaniline in refluxing water in 1:3 molar proportion in the
absence of any Lewis acid catalyst to produce [ZnL03](ClO4)2ꢀ4H2O
and [ZnL003](ClO4)2ꢀH2O, respectively. When the refluxing time is
1 h in the case of 4-methylaniline, the yield is 30%, and when it
is 4 h in the case of 4-methoxyaniline, the yield is 45%. The yield
goes on decreasing in each case when refluxing time is increasingly
more than that specified. Their proton NMR spectra show that in
each case only one sharp methyl signal is obtained. The 1H NMR
spectrum of [ZnL03](ClO4)2ꢀ4H2O is shown in Fig. 2. This implies
that only one diastereomer out of the 23 possibilities is formed.
Thus the aminolysis of the epoxide rings in [ZnL3]2+ by 4-substi-
tuted anilines is diastereoselective. The same diastereomers are
obtained when L0ꢀH2O and L00 are reacted directly with Zn(ClO4)2ꢀ
6H2O in tetrahydrofuran (THF) at room temperature in 70–80%
yield. L0ꢀH2O yields [ZnL03](ClO4)2ꢀ0.75THFꢀ5H2O but L00 gives
[ZnL003](ClO4)2ꢀ4H2O the same complex obtained by aminolysis of
[ZnL3](ClO4)2ꢀ2H2O by 4-methoxyaniline in water. Such selectivity
is not common in inorganic synthesis [9,10]. We have found that
two diastereomers are obtained when L0ꢀH2O is reacted with Ru(-
phen)2Cl2ꢀ2H2O in equimolar proportion in 1:1 (v/v) methanol–
water mixture under refluxing condition to synthesise [Ru(-
phen)2L0](ClO4)2ꢀ2H2O. This conclusion is based on the observation
epoxide ring in L in dichloromethane when alumina is used as a
catalyst [5,6].
H
ð1Þ
''
+
Et2Al N
OMe
L
L
Aminolysis of L is potential in generating two chiral centers, i.e.
22 isomers. But due to the stereoselectivity of the reaction, forma-
tion of only two enantiomers is possible. Hence in a tris metal com-
plex of L, Scheme 1 will render four pairs of enantiomers (i.e. 23
isomers). This fact when coupled with the optical isomerism of a
tris chelate indicates that 23 diastereomers are possible. Because
of our recent interest in diastereoselective synthesis of metal com-
plexes [7], we have prepared the tris L complex of Zn(II) and stud-
ied its reactions with 4-methylaniline and 4-methoxyaniline.
White [ZnL3](ClO4)2ꢀ2H2O is obtained by reacting
L with
Zn(ClO4)2ꢀ6H2O in methanol in 3:1 molar proportion at room tem-
perature. Direct diffusion of diethyl ether to an acetonitrile solu-
tion of [ZnL3](ClO4)2ꢀ2H2O gives single crystals of [ZnL3](ClO4)2ꢀ
MeCN, the X-ray crystal structure of which has been determined.
The structure of the cation [ZnL3]2+ is shown in Fig. 1. The metal
1
of two methyl signals in the H NMR spectrum of [Ru(phen)2L0]-
(ClO4)2ꢀ2H2O (Fig. 2). Incidentally only two diastereomers are in-
deed expected from the reaction of L0ꢀH2O with Ru(phen)2Cl2ꢀ
2H2O because of coupling of the two enantiomers of L0 and the chi-
rality of the hetero tris chelate. Two diastereomers are also ob-
tained in the generation of [Ru(phen)2L00](ClO4)2ꢀ2H2O from the
reaction of L00 with Ru(phen)2Cl2ꢀ2H2O in 1:1 molar proportion in
refluxing 1:1 (v/v) methanol–water mixture. Evidently the diaste-
reoselectivity observed here is metal dependent.
The role of Zn(II) ion in the opening of the epoxide rings is not
clear. Our B3LYP/6-311G⁄⁄ calculations show that while the Mul-
liken charge on the two C atoms of the epoxide ring in the free L
is ꢁ0.020, that in the L chelated to Zn(II) ꢁ0.015. Thus simple elec-
trostatic considerations cannot explain the observed effect of
Zn(II).
3. Experimental
3.1. Materials and physical measurements
5,6-Dihydro-5,6-epoxy-1,10-phenanthroline (L) was procured
from Aldrich. Ru(phen)2Cl2ꢀ2H2O was prepared by a reported pro-
cedure [11]. Microanalyses were performed by a Perkin-Elmer
2400II elemental analyser. Molar conductances were measured
by a Syntronics (India) conductivity meter (model 306) in acetoni-
trile. FTIR spectra (KBr) were recorded on a Shimadzu FTIR-8400S
spectrometer, UV–Vis spectra in acetonitrile on a Perkin Elmer
Lambda 950 spectrophotometer, ESI mass spectra on a Waters Qtof
Micro YA263 spectrometer and 300 MHz NMR spectra on a
Bruker DPX300 spectrometer in deuterated dimethylsulfoxide
(DMSO-d6).
Fig. 1. The structure of the cation in [ZnL3](ClO4)2ꢀMeCN with ellipsoids at 30%
probability. Selected bond distances (Å) and angles (°): Zn1–N31 2.147(3), Zn1–N42
2.155(4), Zn1–N11 2.159(4), Zn1–N51 2.161(3), Zn1–N22 2.171(4), Zn1–N62
2.202(4), N31–Zn1–N42 77.45(13), N31–Zn1–N11 96.89(13), N42–Zn1–N11
95.99(14), N31–Zn1–N51 166.13(14), N42–Zn1–N51 94.80(13), N11–Zn1–N51
95.34(14), N31–Zn1–N22 95.27(13), N42–Zn1–N22 169.17(13), N11–Zn1–N22
76.74(14), N51–Zn1–N22 93.88(13), N31–Zn1–N62 91.92(13), N42–Zn1–N62
91.70(14), N11–Zn1–N62 169.37(13), N51–Zn1–N62 76.67(14), N22–Zn1–N62
96.60(14).

N.K. Shee et al. / Inorganica Chimica Acta 375 (2011) 101–105
103
1
Fig. 2. H NMR spectra (300 MHz) of [ZnL03](ClO4)2ꢀ4H2O (lower trace) and [Ru(phen)2L0](ClO4)2ꢀ2H2O (upper trace) in DMSO-d6. Peaks marked as S are due to the solvent.
3.2. Computation
white compound started appearing). Then the white precipitate,
collected by filtration, was washed with a few drops of methanol
and dried in air. Yield: 275 mg (65%). Anal. Calc. for C36H28N6-
ZnCl2O13: C, 48.61; H, 3.18; N, 9.45. Found: C, 48.48; H, 3.24; N,
The DFT calculations were performed by using GAUSSIAN-03
suite of programs [12]. The inputs were given from the crystal
structure.
W
9.37%. FTIR: v/cmꢁ1: 1142m, 1088vs, 1030m, 625s (ClO4). KM
/
mho cm2 molꢁ1
: 307 (1:2 electrolyte). ESI-MS (CH2Cl2): m/z:
227.9 (95%, ZnL22+), 321.9 (20%, ZnL32+). 1H NMR: d/ppm: 5.07
3.3. Syntheses of L0ꢀH2O
(6H, epoxide), 7.83 (6H, phen), 8.34 (6H, phen), 8.72 (6H, phen).
Method A. L (39 mg, 0.2 mmol) and 4-methylaniline (21 mg,
0.2 mmol) were taken in water (50 ml) and stirred for 72 h. The
white compound precipitated was collected by filtration, washed
with water (2 ml) and dried in vacuo over fused CaCl2. Yield:
55 mg (90%). Method B. The reactants were refluxed for 14 h. The
clear orangish solution was concentrated on a hot plate to 10 ml.
Then it was cooled to room temperature. The yellowish compound
so obtained was collected by filtration and dried in vacuo over
fused CaCl2. Yield: 37 mg (60%). m. p. 239 °C. Anal. Calc. for
3.6. Synthesis of [ZnL03](ClO4)2ꢀ4H2O
A suspension of [ZnL3](ClO4)2ꢀ2H2O (89 mg, 0.1 mmol) and 4-
methylaniline (32 mg, 0.3 mmol) in water (20 ml) was refluxed
for 1 h. Then the hot yellowish solution was filtered and the filtrate
was cooled to room temperature. Solid NaClO4ꢀH2O (1 g) was
added to the cold filtrate and stirred well. After 30 min, the yellow-
ish compound precipitated was collected by filtration and dried in
vacuo over fused CaCl2. Yield: 35 mg (30%). Anal. Calc. for
C19H19N3O2: C, 70.99; H, 5.96; N, 13.07. Found: C, 70.81; H, 5.82;
N, 13.10%. FTIR: v/cmꢁ1: 3371vs (NH). ESI-MS (MeCN): m/z:
342.2 (100%, L0 + K+). 1H NMR: d/ppm: 2.15 (s, 3H, methyl), 4.62
(t, 6 Hz, 1H, CHN), 4.84 (t, 6 Hz, 1H, CHO), 5.69 (d, 6 Hz, 1H, NH),
5.78 (d, 6 Hz, 1H, OH), 6.61 (d, 9 Hz, 2H, phenyl), 6.90 (d, 9 Hz,
2H, phenyl), 7.40 (m, 2H, phen), 7.74 (d, 6 Hz, 1H, phen), 7.89 (d,
6 Hz, 1H, phen), 8.65 (t, 6 Hz, 2H, phen).
C
57H59N9ZnCl2O15: C, 54.90; H, 4.77; N, 10.11. Found: C, 55.10; H,
4.67; N, 10.24%. FTIR: v/cmꢁ1: 3371s (NH); 1115m, 1090vs, 627s
(ClO4). KM/mho cm2 molꢁ1: 285 (1:2 electrolyte). ESI-MS (CH2Cl2):
m/z: 335.3 (45%, ZnL02 ), 486.9 (100%, ZnL032+). 1H NMR: d/ppm:
2+
2.17 (9H, methyl), 4.99 (3H, CHN), 5.11 (3H, CHO), 5.79 (3H, NH),
6.20 (3H, OH), 6.64 (d, 6 Hz, 6H, phenyl), 6.94 (d, 6 Hz, 6H, phenyl),
7.74 (9H, phen), 7.92 (3H, phen), 8.22 (3H, phen), 8.33 (3H, phen).
3.4. Synthesis of L00
3.7. Synthesis of [ZnL03](ClO4)2ꢀ0.75THFꢀ5H2O
Method A. Same as method A for L0. A light grey compound.
Yield: 45 mg (70%). Method B. Same as method B for L0. Yield:
37 mg (60%). m. p. 242 °C (lit. [5] 233–235 °C). Anal. Calc. for
Zn(ClO4)2ꢀ6H2O (37 mg, 0.1 mmol) dissolved in THF (5 ml) was
added dropwise to L0.H2O(96 mg, 0.3 mmol) dissolved in THF
(10 ml) with stirring. Then the yellowish red solution was stirred
for 3 h. Then diethyl ether (30 ml) was added dropwise to the reac-
tion mixture and stirred for 1 h. The yellowish precipitate was fil-
tered off and dried in air. Yield: 85 mg (70%). Anal. Calc. for
C
19H17N3O2: C, 71.44; H, 5.37; N, 13.17. Found: C, 71.56; H, 5.27;
N, 13.07%. FTIR: v/cmꢁ1: 3371vs (NH). ESI-MS (MeCN): m/z:
319.9 (100%, L00 + H+). 1H NMR: d/ppm: 3.64 (s, 3H, methyl), 4.58
(br, 1H, CHN), 4.84 (t, 6 Hz, 1H, CHO), 5.50 (br, 1H, NH), 5.79 (d,
6 Hz, 1H, OH), 6.64–6.74 (4H, phenyl), 7.41 (m, 2H, phen), 7.76
(d, 6 Hz, 1H, phen), 7.89 (d, 6 Hz, 1H, phen), 8.65 (t, 6 Hz, 2H, phen).
C
60H67N9O16.75ZnCl2: C, 54.63; H, 5.12; N, 9.56. Found: C, 54.81;
H, 4.95; N, 9.58%. FTIR:
m
/cmꢁ1: 3371s (NH); 1115s, 1090vs,
623m (ClO4). KM/mho cm2 molꢁ1: 292 (1:2 electrolyte). ESI-MS
2+
3.5. Synthesis of [ZnL3](ClO4)2ꢀ2H2O
(CH2Cl2): m/z: 335.3 (45%, ZnL02 ), 486.9 (100%, ZnL032+). 1H
NMR: d/ppm: 1.76 (t, 3 Hz, 3H, THF), 2.16 (s, 9H, methyl), 3.60 (t,
3 Hz, 3H, THF), 4.99 (3H, CHN), 5.11 (3H, CHO), 5.80 (3H, NH),
6.21 (3H, OH), 6.66 (6H, phenyl), 6.94 (d, 9 Hz, 6H, phenyl), 7.74
(9H, phen), 7.92 (3H, phen), 8.22 (3H, phen), 8.33 (3H, phen).
Zn(ClO4)2ꢀ6H2O (186 mg, 0.5 mmol) dissolved in methanol
(20 ml) was added dropwise to a methanol (20 ml) solution of L
(294 mg, 1.5 mmol) and stirred for 2 h (within 5 min of stirring, a

104
N.K. Shee et al. / Inorganica Chimica Acta 375 (2011) 101–105
3.8. Synthesis of [ZnL003](ClO4)2ꢀH2O
Table 1
Crystallographic data for [ZnL3](ClO4)2ꢀMeCN.
Method A.
A
suspension of [ZnL3](ClO4)2ꢀ2H2O (89 mg,
Formula
M
C38H27Cl2ZnN7O11
893.94
0.1 mmol) and 4-methoxyaniline (37 mg, 0.3 mmol) was refluxed
for 4 h. Then the hot yellowish orange solution was filtered and
the filtrate was cooled to room temperature. Solid NaClO4ꢀH2O
(1.5 g) was added to the cold filtrate and stirred well. After
30 min, the yellowish compound precipitated was collected by fil-
tration and dried in vacuo over fused CaCl2. Yield: 56 mg (45%).
Method B. Zn(ClO4)2ꢀ6H2O (37.2 mg, 0.1 mmol) dissolved in THF
(5 ml) was added drop wise to L00 (96 mg, 0.3 mmol) dissolved in
THF (10 ml) with stirring. Immediately the reaction mixture be-
came yellowish green. Stirring was continued for 3 h. Then diethyl
ether (30 ml) was added dropwise to the reaction mixture and stir-
red for 1 h. The greenish yellow precipitate obtained thereby was
collected by filtration and dried in vacuo over fused CaCl2.
Yield: 110 mg (80%). Anal. Calc. for C57H53N9ZnCl2O15: C, 55.17; H
Space group
Unit cell dimensions
monoclinic, P2(1)/n
a (Å)
b (Å)
c (Å)
b (°)
18.1537(19)
9.6492(5)
22.0754(16)
105.752(9)
3721.7(5)
4, 1.595
23 461
10 551 (Rint = 0.0414)
10 551/0/514
R1 = 0.0841, wR2 = 0.2011
R1 = 0.1261, wR2 = 0.2209
ꢁ0.771 and 1.395
U (Å3)
Z, Dcalc (g cmꢁ3
)
Number of reflections collected
Independent reflections
Data/restraints/parameters
R indices [I > 2r(I)]
R indices (all data)
Largest difference in peak and hole (e Åꢁ3
)
4.31; N, 10.16. Found: C, 54.99; H, 4.25; N, 10.06%. FTIR: v/cmꢁ1
3371s (NH); 1088vs, 1036m, 623s (ClO4). KM/mho cm2 molꢁ1
:
:
10 s. Data analysis was carried out with the CRYSALIS program [13].
The structure was solved using direct methods with the SHELXL97
program [14]. The non-hydrogen atoms were refined with aniso-
tropic thermal parameters. The hydrogen atoms bonded to carbon
were included in geometric positions and given thermal parame-
ters equivalent to 1.2 times those of the atom to which they were
attached. Both perchlorates were disordered in similar fashions
with one oxygen with full occupancy and two sets of three oxygens
with occupancies x and 1 ꢁ x, x being refined to 0.74(1) and
0.69(1). An absorption correction was carried out using the ABSPACK
program [15]. The structure was refined on F2 using SHELXL97 [14].
Selected crystallographic data are given in Table 1.
311 (1:2 electrolyte). ESI-MS (MeCN): m/z: 350.8 (55%, ZnL00 2+),
2
510.3 (100%, ZnL00 2+). 1H NMR: d/ppm: 3.79 (9H, methyl), 4.92
3
(3H, CHN), 5.09 (3H, CHO), 5.59 (3H, NH), 6.17 (3H, OH), 6.69
(6H, phenyl), 6.76 (6H, phenyl), 7.72–7.94 (br, 12H, phen), 8.21
(3H, phen), 8.32 (3H, phen).
3.9. Synthesis of [Ru(phen)2L0](ClO4)2ꢀ2H2O
Ru(phen)2Cl2ꢀ2H2O (57 mg, 0.1 mmol) and L0ꢀH2O (32 mg,
0.1 mmol) taken in 1:1 (v/v) MeOH–H2O mixture (20 ml) were re-
fluxed for 8 h. It was cooled to room temperature and then filtered.
NaClO4ꢀH2O (500 mg) dissolved in water (5 ml) was added to the
filtrate and stirred for 30 min. Then reddish precipitate was filtered
off and dried in vacuo over fused CaCl2. Yield: 75 mg (75%). Anal.
Calc. for C43H37N7O11RuCl2: C, 51.63; H, 3.73; N, 9.81. Found: C,
Acknowledgments
N.K.S. thanks the Council of Scientific and Industrial Research,
New Delhi, India for a fellowship. F.A.O.A. thanks the Third World
Academy of Science, Trieste, Italy and the Indian Association for the
Cultivation of Science, Calcutta, India for a post-doctoral fellow-
ship. M.G.B.D. thanks EPSRC and the University of Reading for
funds for the X-Calibur system. Discussions with and various help
received from Prof. A. Sarkar and Dr. A. Dey are gratefully
acknowledged.
51.62; H, 4.01; N, 9.65%. FTIR:
625 m (ClO4). UV–Vis: kmax/nm
m
/cmꢁ1: 3379s (NH); 1087vs,
/dm3 molꢁ1 cmꢁ1): 450
(e
(22 450), 410 (19 050), 285 (41 450). KM/mho cm2 molꢁ1: 291
(1:2 electrolyte). ESI-MS (MeCN): m/z: 382.4 (100%, Ru(phen)2L02+),
864.2 (10%, Ru(phen)2L0ClO4+). 1H NMR: d/ppm: 2.17 (split, 3H,
methyl), 5.06 (t, 6 Hz, 1H, CHN), 5.16 (m, 6 Hz, 1H, CHO), 5.84 (d,
6 Hz, 1H, NH), 6.26 (d, 6 Hz, 1H, OH), 6.67–8.86 (12 signals, 26H,
aromatic).
Appendix A. Supplementary material
3.10. Synthesis of [Ru(phen)2L00](ClO4)2ꢀ2H2O
CCDC 782744 contains the supplementary crystallographic data
for [ZnL3](ClO4)2ꢀCH3CN. These data can be obtained free of charge
from The Cambridge Crystallographic Data Centre via www.
ccdc.cam.ac.uk/data_request/cif. Supplementary data associated
with this article can be found, in the online version, at
doi:10.1016/j.ica.2011.04.037.
Same as that used for [Ru(phen)2L0](ClO4)2ꢀ2H2O. Reddish pre-
cipitate. Yield: 60 mg (60%). Anal. Calc. for C43H37N7O12RuCl2: C,
50.83; H, 3.67; N, 9.65. Found: C, 51.02; H, 3.47; N, 9.72%. FTIR:
m
nm
/cmꢁ1: 3369s (NH); 1117s, 1088vs, 627m (ClO4). UV–Vis: kmax
/
(e
/dm3 molꢁ1 cmꢁ1): 450 (21 800), 420 (18 900), 285
298 (1:2 electrolyte). ESI-MS
(39 600). KM/mho cm2 molꢁ1
:
2+
(MeCN) m/z: 390.4 (100, Ru(phen)2L00 ), 879.7 (7%, Ru(phen)2L00-
ClO4+). 1H NMR: d/ppm: 3.65 (split, 3H, methyl), 5.03 (2t, 6 Hz,
1H, CHN), 5.17 (m, 6 Hz, 1H, CHO), 5.66 (d, 6 Hz, 1H, NH), 6.23
(d, 6 Hz, 1H, OH), 6.71–8.89 (13 signals, 26H, aromatic).
Caution: Though while working with our metal complexes we
have not met with any incident, care should be taken in handling
them, as perchlorates are potentially explosive. These should not
be prepared and stored in large amounts.
References
[1] M. Widersten, A. Gurell, D. Lindberg, Biochim. Biophys. Acta 1800 (2010) 316.
[2] R. Rink, J. Kingma, J.H.L. Spelberg, D.B. Janssen, Biochemistry 39 (2000) 5600.
[3] C. Philippe, T. Milcent, B. Crousse, D. Bonnet-Delpon, Org. Biomol. Chem. 7
(2009) 2026.
[4] N. Azizi, M.R. Saidi, Org. Lett. 7 (2005) 3649.
[5] C.J. Moody, C.W. Rees, R. Thomas, Tetrahedron 48 (1992) 3589.
[6] E. Schoffers, S.D. Tran, K. Mace, Heterocycles 60 (2003) 769.
[7] S. De, M.G.B. Drew, D. Datta, Inorg. Chim. Acta 363 (2010) 4123.
[8] H. Chen, X. Xu, J. Gao, X. Yang, L. Lu, X. Wang, Huaxue Shiji (Chin) 28 (2006)
478.
3.11. X-ray crystallography
[9] A.V. Zelewsky, O. Mamula, J. Chem. Soc., Dalton Trans. (2000) 219.
[10] J. Crassous, Chem. Soc. Rev. 38 (2009) 830.
[11] P. Bonneson, J.L. Walsh, W.T. Pennington, A.W. Cordes, B. Durham, Inorg.
Chem. 22 (1983) 1761.
[12] M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb, J.R. Cheeseman,
J.A. Montgomery Jr., T. Vreven, K.N. Kudin, J.C. Burant, J.M. Millam, S.S. Iyengar,
J. Tomasi, V. Barone, B. Mennucci, M. Cossi, G. Scalmani, N. Rega, G.A.
Independent data (10 551) were collected for [ZnL3](ClO4)2ꢀ
MeCN with Mo Ka radiation at 150 K using the Oxford Diffraction
X-Calibur CCD System. The crystal was positioned at 50 mm from
the CCD. Frames (321) were measured with a counting time of

N.K. Shee et al. / Inorganica Chimica Acta 375 (2011) 101–105
105
Petersson, H. Nakatsuji, M. Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa,
M. Ishida, T. Nakajima, Y. Honda, O. Kitao, H. Nakai, M. Klene, X. Li, J.E. Knox,
H.P. Hratchian, J.B. Cross, C. Adamo, J. Jaramillo, R. Gomperts, R.E. Stratmann,
O. Yazyev, A.J. Austin, R. Cammi, C. Pomelli, J.W. Ochterski, P.Y. Ayala, K.
Morokuma, G.A. Voth, P. Salvador, J.J. Dannenberg, V.G. Zakrzewski, S.
Dapprich, A.D. Daniels, M.C. Strain, O. Farkas, D.K. Malick, A.D. Rabuck, K.
Raghavachari, J.B. Foresman, J.V. Ortiz, Q. Cui, A.G. Baboul, S. Clifford, J.
Cioslowski, B.B. Stefanov, G. Liu, A. Liashenko, P. Piskorz, I. Komaromi, R.L.
Martin, D.J. Fox, T. Keith, M.A. Al-Laham, C.Y. Peng, A. Nanayakkara, M.
Challacombe, P.M.W. Gill, B. Johnson, W. Chen, M.W. Wong, C. Gonzalez, J.A.
Pople, GAUSSIAN-03, Revision B.03, Gaussian, Inc., Pittsburgh PA, 2003.
[13] CRYSALIS, Oxford Diffraction Ltd., Abingdon, UK, 2006.
[14] G.M. Sheldrick, SHELXL97, University of Göttingen, Germany, 1997.
[15] ABSPACK, Oxford Diffraction Ltd., Oxford, UK, 2005.