The syntheses, characterizations, X-ray crystal structures and properties of Cu(I) complexes of a bis-bidentate schiff base ligand

Article abstract of DOI:10.1016/j.ica.2009.12.009

Bis-bidentate Schiff base ligand L and its two mononuclear complexes [CuL(CH₃CN)₂]ClO₄ (1) and [CuL(PPh₃)₂]ClO₄ (2) have been prepared and thoroughly characterized by elemental analyses, IR

Full text of DOI:10.1016/j.ica.2009.12.009

Inorganica Chimica Acta 363 (2010) 1707–1712
Contents lists available at ScienceDirect
Inorganica Chimica Acta
journal homepage: www.elsevier.com/locate/ica
The syntheses, characterizations, X-ray crystal structures and properties of
Cu(I) complexes of a bis-bidentate schiff base ligand
Anindita Mukherjee a, Rajesh Chakrabarty b, Seik Weng Ng c, Goutam Kumar Patra a,
*
a Department of Chemistry, Vijoygarh Jyotish Ray College, Jadavpur, Kolkata 700 032, India
b Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560 012, India
c Department of Chemistry, University of Malaya, 50603 Kuala Lumpur, Malaysia
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 7 August 2009
Received in revised form 25 November 2009
Accepted 4 December 2009
Available online 4 January 2010
Bis-bidentate Schiff base ligand L and its two mononuclear complexes [CuL(CH3CN)2]ClO4 (1) and
[CuL(PPh3)2]ClO4 (2) have been prepared and thoroughly characterized by elemental analyses, IR, UV–
Vis, NMR spectroscopy and X-ray diffraction analysis. In both the complexes the metal ion auxiliaries
adopt tetrahedral coordination environment. Their reactivity, electrochemical and photophysical behav-
ior have been studied. Complex 1 shows reversible CuII/I couple with potential 0.74 V versus Ag/AgCl in
CH2Cl2. At room temperature L is weakly fluorescent in CH2Cl2, however in Cu(I) complexes 1 and 2 the
emission in quenched.
Keywords:
Schiff bases
Ó 2009 Elsevier B.V. All rights reserved.
Bis-bidentate ligands
N-donor ligands
Copper(I) complex
Crystal structure
Electrochemistry
Photophysics
1. Introduction
and chemical properties of Cu(I) containing proteins and also be-
cause of their diverse structural and physicochemical properties
Schiff bases are significant class of compounds which can be
used in a variety of studies, such as organic synthesis, catalyst
and drug design [1–3] and models for active sites of metalloen-
zymes [4]. They are the most versatile group of chelators for facile
preparation of metal–organic hybrid materials [5–10], single mol-
ecule based magnets [11–16], highly porous materials [17,18],
optoelectronic devices [19–21], and sensors [22–24]. Rational de-
sign of organic ligand plays a vital role in assembling diverse archi-
tectures in the area of supramolecular chemistry [25–27].
Polydentate diazine ligands containing N–N bridge fragments can
produce a variety of structural types, such as helices, polygons,
polyhedra and oligomers [28–32,5] due to the free rotation of the
metal-coordination planes around the N–N single bond. Polyvinyl
chloride membrane electrode based on zinc complex of butane-
2,3-dione bis(salicylhydrazone) are widely used as thiocyanate
sensor. This can further be used in the titration of thiocyanate in
saliva and urine sample [33,34]. The continued interest in coordi-
nation chemistry of Cu(I) is due to the fact that copper(I) com-
plexes of polydentate ligands are the model compounds that can
mimic or even ideally duplicate some of the important physical
[35]. Cu(I) salts catalyses many organic transformations like aryl
guanidinylation [36], amination [37], photocycloaddition [38], oxi-
dation of adrenaline [39], ferrocytrochrome c oxidation [40] and
also olefin cyclopropanation [41].
Herein we report the synthesis of a flexible bis-bidentate ligand
butane-2,3-dione bis(salicylhydrazone), L along with two of its
Cu(I) complexes 1 and 2 (Scheme 1). The complexes have been
characterized by various spectroscopic as well as with single crys-
tal X-ray diffraction method. The reactivity, electrochemical and
photophysical properties of the complexes 1 and 2 have also been
studied.
2. Experimental
2.1. General procedures
2,3-Butane dihydrazone and [Cu(CH3CN)4]ClO4 were synthe-
sized by reported procedures [42,43]. All other reagents were pro-
cured commercially and used without further purification. Copper
was estimated gravimetrically as CuSCN. Microanalyses were car-
ried out using a Perkin–Elmer 2400II elemental analyzer. The melt-
ing point was determined by an Electrothermal IA9000 series
digital melting point apparatus and is uncorrected.
* Corresponding author. Tel.: +91 33 24124082.
E-mail address: patra29in@yahoo.co.in (G.K. Patra).
0020-1693/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2009.12.009

1708
A. Mukherjee et al. / Inorganica Chimica Acta 363 (2010) 1707–1712
Scheme 1. Synthesis of ligand and copper(I) complexes.
Fourier transform infrared (FTIR) and solution electronic spectra
reddish brown clear solution was cooled under argon. Reddish
brown crystals suitable for X-ray analysis separated out, which
were filtered out, and dried in vacuo over fused CaCl2. Yield,
0.185 g (65%). 1H NMR (200 MHz, CDCl3, TMS): d 11.1 (s, 2H),
8.74 (s, 2H), 7.40 (m, 6H), 6.95 (d, 2H), 2.43 (s, 6H), 2.18 (s, 6H),
2.04 (s, 6H). FTIR/cmꢀ1 (KBr): 636(s), 765(s), 905(m), 1091(vs),
1121(vs), 1160(m), 1209(m), 1227(vs), 1315(s), 1375(m),
1470(vs), 1553(vs), 1608(s), 1642(vs), 2235(s), 2931(w),
were recorded on Nicolet Magna-IR (Series II) and Shimadzu UV-
160A spectrophotometers, respectively. 1H NMR and Electrospray
ionization mass (ESI-MS) measurements were made using a Bruker
Advance 400 MHz and Finnigan LCQ Decaxp MAX mass spectrom-
eter, respectively. Fluorescence spectra were recorded on a Perkin–
Elmer LS50B spectrophotometer. All electrochemical measure-
ments were made in dichloromethane on a BAS (Epsilon model)
having a three-electrode setup consisting of a glassy carbon (pol-
ished with alumina before measurement) working, platinum wire
auxiliary and a Ag/AgCl reference electrodes. Oxygen was rigor-
ously removed from the dichloromethane solutions of the samples
by purging with dry argon gas of high purity. Under the experi-
mental conditions employed here, the ferrocene–ferrocenium cou-
3435(wb). UV–VIS kmax/nm (e
/dm3 molꢀ1 cmꢀ1) (CH2Cl2): 322
(18 050); 432 (7500). Elemental analysis of the powdered material
was performed. Anal. Calc. for C22H24N6CuClO6: C, 46.54; H, 4.26;
N, 14.81; Cu, 11.20. Found: C, 46.56; H, 4.35; N, 14.88; Cu, 11.27%.
2.4. Synthesis of [CuL(PPh3)2]ClO4 (2)
ple appears at 0.42 V versus Ag/AgCl in 1 M KCl with an
DEp of
110 mV at a scan rate of 50 mV sꢀ1
.
0.161 g (0.5 mmol) of L was dissolved in 75 mL of dry chloro-
form. Argon was purged through the solution for 15 min. Then to
2.2. Synthesis of butane-2,3-dione bis(salicylhydrazone) (L)
this
orange
yellow
solution
0.365 g
(0.5 mmol)
of
[Cu(PPh3)2(CH3CN)2]ClO4 was added with stirring. The color of
the reaction mixture gradually changed from yellow to red. The
red reaction mixture was stirred at room temperature for 2 h under
argon atmosphere. Red solid separated out. It was filtered off,
washed with little amount of chloroform and dried in vacuo over
fused CaCl2. Yield, 0.388 g (76%). Red crystals suitable for X-ray
analysis were grown by slow evaporation of its methanol solution.
1H NMR (200 MHz, CDCl3, TMS): d 8.72 (s, 2H), 7.49 (m, 4H), 7.44–
7.39 (m, 30H) 6.89 (t, 4H), 2.43 (s, 6H). FTIR/cmꢀ1 (KBr): 506(s),
518(vs), 526(s), 549(vs), 620(s), 645(s), 667(s), 695(s), 725(s),
744(s), 761(s), 805(s), 890(m), 958(m), 995(vs), 1028(vs),
1070(s), 1089(vs), 1129(vs), 1158(vs), 1125(vs), 1276(s),
1312(m), 1329(m), 1434(vs), 1451(vs), 1461(m), 1478(s),
1508(m), 1564(vs), 1583(m), 1609(vs), 1627(vs), 1649(vs),
2,3-Butane dihydrazone (0.57 g, 5 mmol) was dissolved in
50 mL of anhydrous chloroform. To this solution, 1.22 g (10 mmol)
of freshly distilled salicylaldehyde was added. The resulting bright
yellowish mixture was refluxed for 2 h, maintaining a dry atmo-
sphere. Within 30 min of reflux orange yellow solid started sepa-
rating out. After 2 h, the reaction mixture was cooled to room
temperature and the product was collected by filtration. Crystals
suitable for X-ray analysis were obtained by slow evaporation of
chloroform solution. Yield, 1.44 (90%); mp > 250 °C. 1H NMR
(200 MHz, CDCl3, TMS): d 11.81 (s, 2H), 8.68 (s, 2H), 7.39 (m,
4H), 7.10 (d, 2H), 6.90 (t, 2H), 2.43 (s, 6H). FTIR/cmꢀ1 (KBr):
506(s), 562(w), 647(m), 713(s), 757(vs), 790(m), 896(w), 981(w),
1019(s), 1040(s), 1123(m), 1160(m), 12099s), 1271(vs), 1361(s),
1406(m), 1447(m), 1497(m), 1547(s), 1581(m), 1612(vs),
1626(vs), 2407(w), 2779(w), 2851(m), 2945(w), 3431(wb). ESI
2925(m), 3080(s), 3227(w), 3432(wb). UV–VIS kmax/nm (e
/dm3
molꢀ1 cmꢀ1) (CH2Cl2): 312 (10 500); 443 (8250). Anal. Calc. for
C54H48N4P2CuClO6: C, 64.20; H, 4.79; N, 5.55; Cu, 6.30. Found: C,
64.28; H, 4.88; N, 5.63; Cu, 6.36%.
MS: 323.2 (LH+, 100%). UV–VIS kmax/nm ( /dm3 molꢀ1 cmꢀ1
e )
(CH2Cl2): 238 (15 080); 307 (21 450); 366 (10 970). Anal. Calc. for
C18H18N4O2: C, 67.05; H, 5.63; N, 17.39. Found: C, 67.07; H, 5.69;
N, 17.32%.
2.5. X-ray crystallography
2.3. Synthesis of [CuL(CH3CN)2]ClO4 (1)
X-ray diffraction data for crystalline samples of 1, 2 and L were
collected using Mo Ka radiation (0.71073 Å) on a Bruker KAPPA
0.161 g (0.5 mmol) of L was dissolved in 75 ml of dry chloro-
form. Argon was purged through the solution for 15 min and to this
orange yellowish solution 0.165 g (0.5 mmol) of [Cu(CH3CN)4]ClO4
was added at a time. The reddish brown reaction mixture was stir-
red at room temperature for 2 h under argon atmosphere. Then the
APEX II diffractometer. The SMART [44] program was used for col-
lecting frames of data, indexing the reflections, and determination
of lattice parameters; SAINT [44] program for integration of the
intensity of reflections and scaling; SADABS [45] program for absorp-
tion correction. The structures were solved by direct methods (SHEL-

A. Mukherjee et al. / Inorganica Chimica Acta 363 (2010) 1707–1712
1709
XS-97) and standard Fourier techniques, and refined on F2 using full
matrix least squares procedures (SHELXL-97) using the SHELX-97 pack-
age [46] incorporated in WINGX [47]. All non-hydrogen atoms were
refined anisotropically except for the oxygen atom in the partially
occupying water molecules in 1 which are in a disordered state.
The hydrogen atoms were assigned idealized positions and given
thermal parameters equivalent to either 1.5 (methyl hydrogen
atoms) or 1.2 (all other hydrogen atoms) times the thermal param-
eter of the carbon atoms to which they were attached.
for L and 1, respectively. The phenyl protons of PPh3 in 3 resonate
at d 7.44–7.39 ppm.
3.3. UV–Vis and photophysical data
The absorption spectra of L (in dichloromethane) shows intra-li-
gand charge transfer bands at 238 nm (
307 nm (
, 21 450 Mꢀ1 cmꢀ1) and 366 nm (
274 nm (
, 28 100 Mꢀ1cmꢀ1), respectively. These charge transfer
bands appear at 322 nm (
, 18 050 Mꢀ1 cmꢀ1) and 312 nm (
10 500 Mꢀ1 cmꢀ1) for 1 and 2, respectively. The Cu(I) complexes
1 and 2 display broad unstructured band at 432 nm (
, 7500 Mꢀ1
cmꢀ1) and 443 nm ( , 8250 Mꢀ1cmꢀ1), respectively, which is sup-
e
, 15 080 Mꢀ1 cmꢀ1),
e
e
, 10 970 Mꢀ1 cmꢀ1),
e
e
e,
3. Results and discussion
e
3.1. Synthesis of ligand and copper(I) complexes
e
posed to be MLCT in origin, and these bands are responsible for
characteristic color in complexes 1 and 2.
Syntheses of the copper(I) complexes 1 and 2 were achieved by
reaction of ligand L with appropriate Cu(I) precursor complexes in
equimolar ratio under inert atmosphere at room temperature.
Reaction of L with [Cu(CH3CN)4](ClO4) in anhydrous chloroform
under argon atmosphere in 1:1 ligand-to-metal ratio yielded
[Cu(L)(CH3CN)2]ClO4 (1) as reddish brown blocks. The solid is fairly
stable in air, but its CHCl3 and CH2Cl2 solution were stable in air
only for about 24 h. Treatment of [Cu(PPh3)2(CH3CN)2]ClO4 with
L in dry chloroform under argon at room temperature with an
equimolar amount resulted in the formation of a red solid. From
its methanol solution red crystals [Cu(L)(PPh3)2]ClO4 (2) were ob-
tained. Complex 2 can also be obtained by replacing the CH3CN
in 1 with PPh3 in 2:1 M ratio. The solubility of complex 2 is higher
in common organic solvents compared to complex 1. The relative
stability of the complexes in solution is also higher in the case of
complex 2. Ligand L was earlier utilized to synthesize Zn(II) com-
plexes for thiocynate ion-selective PVC based membrane electrode
[33]. However, the complex was not structurally characterized.
From their physicochemical characterization Ardakani et al. [33]
inferred that N, O donor atoms in the ligand moiety are disposed
in a convergent manner, however as observed form the X-ray crys-
tal structural studies (vide infra) in the present study the N, O do-
nors in the ligand moiety as well as in the copper(I) complexes are
disposed in a divergent fashion.
Upon excitation at 315 nm (within the charge transfer enve-
lope) at room temperature at dichloromethane the ligand L shows
a weak emission band with maxima around 425 nm (Fig. 1). The
emission quantum yield (/) is determined to be 8.2 ꢁ 10ꢀ5, against
quinine sulfate in 0.1 N H2SO4 [48]. The emission can be tentatively
assigned to the intra-ligand fluorescent emission, which is related
to the energy gap between the p–p p-con-
* molecular orbital of the
jugation of the ligand system. It has been found that the emission
is quenched in both the complexes 1 and 2. Quenching of fluores-
cence by paramagnetic and diamagnetic metal ions is well docu-
mented [49,50]. This might be due to the electron transfer by
heavy atom.
3.4. Electrochemistry
The electrochemical properties of the copper(I) complexes
[Cu(L)(CH3CN)2]ClO4 (1) and [CuL(PPh3)2]ClO4 (2) have been stud-
ied by cyclic voltammetry in dichloromethane at glassy carbon
electrode under dry argon atmosphere. The complex 1 shows a
reversible voltammogram with single CuI–CuII couple, occurring
at E = 0.74 V (versus Ag/AgCl in 1 M KCl, scan rate 50 mV sꢀ1
(Fig. 2). The
)
½
D
Ep value is 160 mV at 50 mV sꢀ1 scan rate and it in-
creases as the scan rate is increased. The electrode process is de-
scribed by the Eq. (1) (where X = CH3CN). However, under the
similar conditions the complex 2 does not show a well defined
voltammogram.
3.2. IR and NMR spectroscopy
The mononuclear Cu(I) complexes 1 and 2 under study show
characteristic peaks due to the ligation of the ligand L to the metal
center in the KBr-phase IR spectra. In the IR spectrum of ligand L,
characteristic band at 1626 cmꢀ1 is assigned to the imine (C@N)
stretching frequency. This band due to C@N stretching is shifted
to lower energy and appear at around 1642 cmꢀ1 and 1649 cmꢀ1
in the complexes 1 and 2, respectively. A sharp band observed at
2235 cmꢀ1 in complex 1 indicates the existence of C„N, which is
absent in the IR spectra of L and 2. The weak and broad band
around 3431 cmꢀ1 in the IR spectrum of L is assigned to be due
to O–H stretching. There is not much shift of this band in the com-
plexes 1 and 2 indicating the non-involvement of this group in
coordination with the metal ion. The strong bands around 1435,
744, 695 and 506 cmꢀ1 are due to the presence of PPh3 group in
the complex 2. The typical strong baꢀnds due to the stretching
vibrations of the non-coordinated ClO4 ions in 1 and 2 appear at
the expected regions; 1091 and 636 cmꢀ1 (for 1); 1089 and
620 cmꢀ1 (for 2).
ð1Þ
The 1H NMR spectra of the ligand L in CDCl3 shows a singlet at d
8.68 ppm due to (HC@N) moiety. The downfield shift of the peak to
around d 8.74 and d 8.72 ppm in case of 1 and 2, respectively, indi-
cates the coordination of the ligand L to the metal center. However,
no significant shift compared to ligand L is observed for the outly-
ing methyl protons in the complexes 1 and 2 and appears at around
d 2.43 ppm. The –OH proton resonates at d 11.81 and d 11.10 ppm
Fig. 1. Emission spectra of L in dichloromethane at room temperature on excitation
at 315 nm.

1710
A. Mukherjee et al. / Inorganica Chimica Acta 363 (2010) 1707–1712
3.5. Reactivity
In our preliminary attempt to prepare heteroleptic (mixed li-
gands) complexes of L, and to compare the Lewis basicity of L to
other two bispyridyl ligands [NC5H4CH@N–N@CHC5H4N] (A) and
[NC5H4CH@N–N@C(Ph)–C(Ph)@N–N@CHC5H4N] (B), we reacted
complex 1 with (A) and (B) in equimolar proportion under inert
atmosphere, expecting that the two-cis oriented labile CH3CN mol-
ecules in 1 will be replaced by A or B. But we have seen both the
bispyridyl ligands A and B form stable homoleptic Cu(I) complexes,
3 and 4, completely removing the ligand L as well as the CH3CN
molecules. The products 3 and 4 were characterized by multinu-
clear NMR spectroscopy and elemental analyses [3: 1H NMR
(200 MHz, DMSO-d6, TMS); d 8.69 (8H), 8.53 (4H), 7.73 (8H). Ele-
mental analysis: C, 49.45; H, 3.51; N, 19.17%. 4: 1H NMR
(200 MHz, DMSO-d6, TMS); d 8.61 (8H), 8.43 (4H), 7.86 (8H),
7.56–7.30 (20H). Elemental analysis: C, 62.75; H, 4.12; N,
16.78%]. This observation supports that the ligand L has less Lewis
basicity compared to A and B.
Fig. 2. Cyclic voltammogram for [CuL(CH3CN)2]ClO4 (1) in CH2Cl2/0.1 M Bu4NClO4
at the scan rate of 50 mV sꢀ1
.
3.6. Structural description
Table 1
The structures of the ligand L and the complexes 1 and 2 were
determined by single crystal X-ray diffraction. The crystallographic
data and refinement parameters are presented in Table 1. A struc-
tural representation for the free ligand L is shown Fig. 3. It is char-
acterized by an extended conformation with an anti conformation
about the central C–C bond. Upon reaction with tetrahedral
[Cu(CH3CN)4]ClO4 complex, the ligand L adopts a syn conformation
in complex 1 (Fig. 4) in order to optimize the tetrahedral coordina-
tion environment of copper(I) center. The distorted tetrahedral
coordination geometry of copper(I) center in 1 is completed by
the two N atoms of two different diazine fragments of the ligand
L and two acetonitrile molecules. The corresponding Cu–N bond
Crystallographic data and refinement parameters for 1, 2 and L.
1
2
L
Formulaa
C22H33N6O11.5ClCu C54H46N4O6P2ClCu C18H18N4O2
664.53
Formula weight
1007.88
322.36
(g molꢀ1
)
a
Crystal system
Space group
T (K)
a (Å)
b (Å)
monoclinic
C2/c
triclinic
P1
140(8)
monoclinic
P21/n
ꢀ
293(2)
23.365(4)
18.523(4)
14.332(2)
90
94.549(3)
90
6183.3(18)
4
293(2)
18.054(4)
4.6824(10)
19.780(4)
90
101.051(5)
90
1641.1(6)
4
10.9575(2)
14.9373(3)
15.5481(3)
80.0210(10)
86.906(2)
84.6800(10)
2493.68(8)
2
c (Å)
a
(°)
b (°)
c
(°)
V (Å3)
Z
qcalcd (g cmꢀ3
)
1.404
0.856
1.342
0.610
1.305
0.088
l
(mmꢀ1
)
Collected reflections 29 014
20 736
6177
Unique reflections
Rint
5421
0.0360
1.152
11 239
0.0371
1.024
1026
0.0575
1.074
Goodness of fit
(GOF) on F2
b
Final R1
,
0.0820, 0.2573
0.1059, 0.2904
0.0473, 0.1051
0.0809, 0.1233
0.0353,
0.0900
0.0504,
0.0995
c
wR2 (I P 2
r)
R1, wR2 (all data)
a
b
c
Including solvate molecules.
R1
= R||Fo| – |Fc||/R|Fo|.
wR2 = {
R
[w(F2o ꢀ F2c )2]/
R r
[w(F2o )2]}1/2 where w = 1/[ 2(F2o ) + (aP)2 + bP] with P is
[2F2c + Max(F2o ,0)]/3.
Fig. 4. Molecular representation of [CuL(CH3CN)2]ClO4 (1). Hydrogen atoms were
omitted for clarity.
Fig. 3. Molecular representation of butane-2,3-dione bis(salicylhydrazone), L.

A. Mukherjee et al. / Inorganica Chimica Acta 363 (2010) 1707–1712
1711
Table 2
Selected bond distances (Å) and angles for 1, 2.
Complex 1
Cu(1)–N(1)
Cu(1)–N(6)
2.056(4)
1.971(6)
Cu(1)–N(2)
N(1)–N(3)
2.058(4)
1.399(5)
Cu(1)–N(5)
N(2)–N(4)
1.939(5)
1.401(5)
N(5)–Cu(1)–N(6)
N(6)–Cu(1)–N(1)
N(6)–Cu(1)–N(2)
105.1(2)
118.77(16)
112.12(17)
N(5)–Cu(1)–N(1)
N(5)–Cu(1)–N(2)
N(1)–Cu(1)–N(2)
120.12(18)
121.74(18)
77.81(15)
Complex 2
Cu(1)–N(1)
Cu(1)–P(2)
2.098(2)
2.255(8)
Cu(1)–N(2)
N(1)–N(3)
2.070(2)
1.402(3)
Cu(1)–P(1)
N(2)–N(4)
2.281(8)
1.402(3)
N(2)–Cu(1)–N(1)
N(1)–Cu(1)–P(2)
N(1)–Cu(1)–P(1)
76.34(9)
116.09(7)
109.58(7)
N(2)–Cu(1)–P(2)
N(2)–Cu(1)–P(1)
P(2)–Cu(1)–P(1)
114.18(7)
107.30(7)
123.48(3)
part in metal-coordination because of the incompatibility of soft
Cu(I) ion with hard Oꢀ ion and also due to the free rotation of N–
N bond, the N, O donor atoms in the ligand moiety are disposed
in a divergent fashion. Moreover it should be taken in account that
as the Cu(I) complexes were synthesized in an aprotic solvent and
in the absence of any base, the deprotonation of ligand L (which is
pre-requisite for coordination) is hindered.
Acknowledgement
G.K.P. thanks the Department of Science and Technology, Gov-
ernment of India, New Delhi for financial support.
Appendix A. Supplementary data
CCDC 738343, 738344 and 738345 contain the supplementary
crystallographic data for the ligand L and the Cu(I) complexes 1
and 2. These data can be obtained free of charge from The Cam-
bridge Crystallographic Data Centre via http://www.ccdc.cam.a-
c.uk/data_request/cif. Supplementary data associated with this
article can be found, in the online version, at doi:10.1016/
j.ica.2009.12.009.
Fig. 5. Molecular representation of [CuL(PPh3)2]ClO4 (2). Hydrogen atoms were
omitted for clarity.
distances (Table 2) are Cu–N(imine), 2.056(4) and 2.058(4) Å, and
Cu–N(acetonitrile), 1.939(5) and 1.971(6) Å and are consistent
with literature values [5]. The N–Cu–N angles ranges from
77.80(2) to 121.70(2).
References
The structure of the complex 2 is shown in Fig. 5, and important
bond distances and angles are included in Table 1. The complex 2
has identical conformational features with 1 having a distorted tet-
rahedral copper(I) as the central metal atom. Each copper atom
coordinates simultaneously to two nitrogen atoms of the two dif-
ferent N–N diazine moieties of ligand L with two PPh3 molecules
completing the tetrahedral geometry. The Cu–N and Cu–P dis-
tances are typical [5] and ranges from 2.070(2) to 2.098(2) and
2.255(8) to 2.281(8), respectively. The increased crowding at the
copper center forces one of the phenyl rings to deviate from pla-
narity in complex 2. The two phenyl rings make dihedral angle of
80.2° with each other. This is in contrast to the observation in com-
plex 1 where the two outlying phenyl rings are coplanar with each
other with N–C–C–N torsion angle being 180°.
[1] S. Yamada, Coord. Chem. Rev. 190 (1999) 537.
[2] S. Akine, T. Taniguchi, W. Dong, S. Masubuchi, T. Nabeshima, J. Org. Chem. 70
(2005) 1704.
[3] W.-K. Dong, Y.-X. Sun, Y.-P. Zhang, L. Li, X.-N. He, X.-L. Tong, Inorg. Chim. Acta
362 (2009) 117. and references therein.
[4] M.F. Summers, L.G. Marzilli, N. Bresciani-Pahor, L. Randaccio, J. Am. Chem. Soc.
106 (1984) 4478.
[5] G.K. Patra, I. Goldberg, Cryst. Growth Des. 3 (2003) 321.
[6] G.K. Patra, I. Goldberg, J. Chem. Soc., Dalton Trans. (2002) 1051.
[7] E.-Q. Gao, Z.-M. Wang, C.-H. Yan, Chem. Commun. (2003) 1748.
[8] K.L. Mulfort, J.T. Hupp, J. Am. Chem. Soc. 126 (2004) 13236.
[9] B. Kesanli, Y. Cui, M.R. Smith, E.W. Bittner, B.C. Bockrath, W. Lin, Angew. Chem.,
Int. Ed. 116 (2004) 2388.
[10] J. Chakraborty, S. Thakurta, G. Pilet, R.F. Ziessel, L.J. Charbouniere, S. Mitra, Eur.
J. Inorg. Chem. (2009) 3993.
[11] O. Kahn (Ed.), Magnetism:
Publishers, 1996.
A Supramolecular Function, Kluwer Academic
[12] K. Itoh, M. Kinoshita (Eds.), Molecular Magnetism, New Magnetic Materials,
Gordan Beach, Kodansha, Tokyo, 2000.
[13] M. Kumroo, Chem. Soc. Rev. 38 (2009) 1353.
4. Conclusions
[14] S.M. Humphery, P.T. Wood, J. Am. Chem. Soc. 126 (2004) 13236.
[15] H. Grove, T.L. Kelley, L.K. Thompson, L. Zhao, Z. Xu, T.S.M. Abedin, D.O. Miller,
A.E. Goeta, C. Wilson, J.A.K. Howard, Inorg. Chem. 43 (2004) 4278.
[16] E.-Q. Gao, S.-Q. Bai, Z.-M. Wang, C.-H. Yan, J. Am. Chem. Soc. 125 (2003) 4984.
[17] H.K. Chae, D.Y. Siberio-Perez, J. Kim, Y. Go, M. Eddaoudi, A.J. Matzger, M.O.
Keefee, O.M. Yaghi, Nature 427 (2004) 523.
[18] A.R. Kennedy, K.G. Brown, D. Graham, J.B. Kirkhouse, M. Kittner, C. Major, C.L.
Mchugh, P. Murdoch, W.E. Smith, New J. Chem. 29 (2005) 826.
[19] Y. Li, Z.-X. Zhang, K.C. Li, W.-D. Song, Q.-S. Li, Inorg. Chem. Commun. 10 (2007)
1557.
In a search of new metal ion complexes of Cu(I) with interesting
features we have synthesized two new Cu(I) complexes 1 and 2
using flexible polydentate diazine ligand L and investigated their
structural, photophysical, electrochemical properties and reactivi-
ties. In the present study it was observed that the phenolate oxy-
gens didn’t coordinate to the metal ion. The non-involvement of
phenoxide ion in the coordination with Cu(I) center is contrary
to the usual binding modes observed in similar type of salen li-
gands with metal ions [51,52]. The phenolate oxygens did not take
[20] X.-H. Bu, M.L. Tong, H.-C. Cang, S. Kitagawa, S.-R. Batten, Angew. Chem., Int. Ed.
Engl. 43 (2004) 192.
[21] B. Sui, W. Zhao, G.-H. Ma, T.A. Okamura, J. Fan, Y.-Z. Li, S.-H. Tang, W.-Y. San, N.
Ueyama, J. Mater. Chem. 14 (2004) 163.

1712
A. Mukherjee et al. / Inorganica Chimica Acta 363 (2010) 1707–1712
[22] Y. Bai, G.J. He, Y.G. Zhao, C.Y. Duan, D.B. Dang, Q.J. Meng, Chem. Commun.
(2006) 1530.
[23] Y. Li, G.-Q. Li, W.-Q. Zou, F.-K. Zheng, J.P. Zou, G.-C. Guo, C.-Z. Lu, J.-S. Huang, J.
Mol. Struct. 837 (2007) 231.
[24] E.Y. Lee, S.Y. Jang, M.P. Suh, J. Am. Chem. Soc. 127 (2005) 6374.
[25] M. Maekawa, H. Konaka, Y. Suenga, T. Kuroda-Sowa, M. Munakata, J. Chem.
Soc., Dalton Trans. (2000) 4160.
[26] E.-Q. Gao, A.-L. Cheng, Y.-X. Xu, M.-Y. He, C.-H. Yan, Inorg. Chem. 44 (2005)
8822.
[27] R. Peng, D. Li, T. Wu, X.-P. Zhou, S.W. Ng, Inorg. Chem. 45 (2006) 4035.
[28] L. Zhao, V. Niel, L.K. Thompson, Z. Xu, V.A. Milway, R.G. Harvey, D.O. Miller, C.
Wilson, M. Leech, J.A.K. Howard, S.L. Heath, Dalton (2004) 1446.
[29] J.-M. Lehn, Supramolecular Chemistry: Concept and Perspectives, VCH,
Weinheim, 1995.
[36] G. Evindar, R.A. Batey, Org. Lett. 5 (2003) 133.
[37] B. Goodbrand, N.X. Hu, J. Org. Chem. 64 (1999) 670.
[38] R.G. Salomon, J.K. Kochi, J. Am. Chem. Soc. 96 (1974) 1137.
[39] J. Huang, M. Li, Y. Tang, H. Fang, L. Ding, J. Wuham, Univ. Technol. Mater. 23
(2008) 606.
[40] A.J. Davison, J. Biol. Chem. 243 (1968) 6064.
[41] G.A. Ardiazzoia, S. Brenna, F. Castelli, S. Galli, Inorg. Chim. Acta 362 (2009)
3507.
[42] D.H. Busch, J.C. Bailor, J. Am. Chem. Soc. 78 (1956) 1137.
[43] P. Hemmerich, C. Sigwart, Experientia 19 (1963) 488.
[44] SMART and SAINT Software Reference Manuals, Version 5.0, Bruker AXS Inc.,
Madison, WI, 1998.
[45] G.M. Sheldrick, SADABS, Bruker Nonius Area Detector Scaling and Absorption
Correction, Version 2.05, University of Göttingen, Göttingen, Germany, 1999.
[46] G.M. Sheldrick, Acta Crystallogr., Sect. A64 (2008) 112.
[30] C.-Y. Su, Y.-P. Cai, C.-L. Chen, M.D. Smith, W. Kaim, H.C. Zur Loye, J. Am. Chem.
Soc. 125 (2003) 8595.
[47] L.J. Farrugia, WINGX: An Integrated System of Windows Programs for the
[31] O. Sun, Y. Bai, G.J. He, C.Y. Duan, Z.H. Lin, Q.J. Mang, Chem. Commun. (2006)
2777.
[32] Y. Mulyana, C.J. Kepert, L.F. Lindoy, A. Parkin, P. Turner, Dalton Trans. (2005)
1598.
Solution, Refinement and Analysis for Single Crystal X-ray Diffraction Data,
Version 1.80.01, Department of Chemistry, University of Glasgow, 2003 (J.
Appl. Crystallogr. 32 (1999) 837).
[48] J.N. Demas, G.A. Crosby, J. Phys. Chem. 75 (1971) 991.
[33] M.M. Ardakani, A. Sadeghi, H. Salavati-Niasari, Talanta 66 (2005) 837.
[34] A.B. Bedtsen, E.H. Hansen, Analyst 116 (1991) 647.
[35] T.N. Sorrell, M.R. Malachowski, Inorg. Chem. 22 (1983) 1883. and references
therein.
[49] J.J. Brege, C. Gallaway, A.R. Barron, J. Phys. Chem. C 113 (2009) 4270.
[50] A. Coskun, E.U. Akkaya, J. Am. Chem. Soc. 127 (2005) 10464.
[51] Y. Bai, J. Liu, D.-B. Dang, C.-Y. Duan, Acta Crystallogr., Sect. E62 (2006) m1805.
[52] Y. Bai, D.-B. Dang, C.-Y. Duan, Acta Crystallogr., Sect. E62 (2006) m2599.