Syntheses, crystal structures and optical properties of heteroleptic copper(I) dithio/PPh3 complexes

Article abstract of DOI:10.1016/j.poly.2014.04.068

New heteroleptic copper(I) dithiocarbamate and xanthate complexes of the general formula [(PPh₃)₂CuL] (L = N-(4-pyridyl)-N- furfuryldithiocarbamate L1 (1), thiomorpholinedithiocarbamate L2 (2), phenylpiperazinedithiocarbamate L3 (3),

Full text of DOI:10.1016/j.poly.2014.04.068

Accepted Manuscript
Syntheses, Crystal Structures and Optical Properties of Heteroleptic Copper(I)
Dithio/PPh3 Complexes
Ajit N. Gupta, Vikram Singh, Vinod Kumar, Lal Bahadur Prasad, Michael G.B.
Drew, Nanhai Singh
PII:
S0277-5387(14)00296-4
DOI:
http://dx.doi.org/10.1016/j.poly.2014.04.068
POLY 10712
Reference:
Polyhedron
To appear in:
Received Date:
Accepted Date:
7 March 2014
28 April 2014
Please cite this article as: A.N. Gupta, V. Singh, V. Kumar, L.B. Prasad, M.G.B. Drew, N. Singh, Syntheses, Crystal
Structures and Optical Properties of Heteroleptic Copper(I) Dithio/PPh3 Complexes, Polyhedron (2014), doi: http://
dx.doi.org/10.1016/j.poly.2014.04.068
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Syntheses, Crystal Structures and Optical Properties of Heteroleptic
Copper(I) Dithio/PPh3 Complexes
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Ajit N. Guptaa, Vikram Singha, Vinod Kumara, Lal Bahadur Prasada, Michael G. B.
Drewb and Nanhai Singh*a
a Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi 221005, India
Fax: +91-542-2386127, E-mail: nsingh@bhu.ac.in, nsinghbhu@gmail.com
b Department of Chemistry, University of Reading, Whiteknights, Reading, RG6 6AD (U.K.)
Abstract
New heteroleptic copper(I) dithiocarbamate and xanthate complexes of the general formula
[(PPh3)2CuL]
(L
=
N-(4-pyridyl)-N-furfuryldithiocarbamate
L1
(1),
thiomorpholinedithiocarbamate L2 (2), phenylpiperazinedithiocarbamate L3 (3),
furfurylxanthate L4 (4) and pyridine-4-xanthate L5 (5) have been synthesized by metathesis
reactions of the precursor complex [Cu(PPh3)2NO3] and potassium salts of the ligands (KL)
in an equimolar ratio. These complexes have been characterized by elemental analysis and
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spectroscopy (IR, UV-Vis., H, C and 31P NMR), and their structures have been elucidated
by X-ray crystallography. In all the five structures, the copper atoms are found to reside
within a four coordinate (P2S2) distorted tetrahedral geometry. The non-linear optical
properties of 1-5 and the electronic absorption bands of 1 and 5 have been studied by DFT
and TD-DFT methods respectively. All the complexes are strongly luminescent in
dichloromethane solution at room temperature. The pressed pellet σrt values of ~10-8-10-5 S
cm-1 show their weakly conducting behavior.
Keywords:
Copper(I);
Crystal
structures;
Density
functional
calculations;
Photoluminescence; Non-linear optics.

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1. Introduction
Metal dithiocarbamates and xanthates have occupied an important position in the field of
metal dithiolate chemistry because of their interesting conducting, magnetic and optical
properties, their use as MOCVD precursors for the preparation of metal sulfides and their
application in the vulcanization of rubber, flotation agents in metallurgy, medicine,
agriculture and biological systems [1-5]. A developing interest in dithiocarbamate and
xanthate ligand chemistry is the functionalization of the substituents on the dithio unit which
may facilitate more complex architectures and modify the physical properties of the resulting
complexes. The multifarious chemistry and remarkable differences in behaviour may be
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ascribed to the dominant contribution of the canonical forms R2N+=CS22- and ROCS2 in the
dithiocarbamate and xanthate ligand complexes.
Homo- and heteroleptic copper(I) complexes have attracted considerable attention in recent
years, mainly because of their intriguing photoluminescent properties with potential
application as sensors, biological probes, display devices and solar energy conversion
processes [9,10]. Dithiocarbamates show the capability to stabilize the +II and +III oxidation
states of copper [1a-c,f]. On the contrary, xanthate ligands reduce copper(II) into copper(I). It
is interesting to note that both dithiocarbamate and xanthate ligands, in combination with
strong σ-donor and π-acceptor phosphine ligands, show the capability to stabilize the +I
oxidation state of the copper. Copper(I) 1,1-dithiolates and their phosphine adducts are
known to have monomeric, dimeric and cluster structures [6-8]. Heteroleptic dithio
complexes of the form [CuI(S-S)(PR3)2] (R= Me, OMe, Et; S-S = xanthate, dithiocarbamate)
have dimeric structures, whereas analogous dithio compounds with bulky phosphine ligands
are mononuclear [6a,7]. Despite their synthetic versatility and interesting optical properties,
mixed-ligand copper(I) dithio-phosphine complexes with a CuP2S2 core remain scarce in the
literature [7a,14].
Given these facts, it was considered worthwhile to undertake the synthesis of new
heteroleptic copper(I) complexes derived from pyridyl, thiomorpholine, phenylpiperazine or
furfuryl functionalized dithiocarbamates/xanthates and PPh3 ligands and to investigate their
crystal structures, luminescent, molecular electrical conductivities and non-linear optical
properties. The important aspect of undertaking this work stems from the following, which
are important contributions affecting the strong luminescent properties of the complexes: (i)
the electron rich nature of the substituents which may enhance the conjugation of charge in
the complexes, (ii) the steric bulk of the PPh3 and chelating dithio ligands which may
enhance the conformational rigidity about the metal centre and (iii) the rigid coordination

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environment thus formed which may control the possible ligand dissociation from the excited
state. DFT calculations have been performed to examine the second order non-linear optical
activity. The UV-Vis absorptions have been assigned using the TD-DFT method. The results
of these investigations are described in this contribution.
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2. Experimental section
2.1. Materials and measurements
All experiments were performed under aerobic conditions at ambient temperature and
pressure. The chemicals 4-pyridinemethanol, thiomorpholine (all Sigma-Aldrich), pyridine-4-
aldehyde, furfuryl amine, N-phenylpiperazine and furfurylalcohol (all SPECTROCHEM)
were used as received in the syntheses of the dithio ligands. The potassium salts of the
ligands N-(4-pyridyl)-N-furfuryldithiocarbamate (KL1), thiomorpholinedithiocarbamate
(KL2), phenylpiperazinedithiocarbamate (KL3), furfurylxanthate (KL4) and pyridine-4-
xanthate (KL5) were prepared by reacting the appropriate secondary amines/alcohols with
KOH and CS2 in THF according to previously reported procedures [5a,7a] and characterized
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by IR, H and C NMR spectra. The precursor [Cu(PPh3)2NO3] used in the synthesis of the
heteroleptic complexes was synthesized by a literature procedure [16]. The solvents were
purified according to standard literature methods.
The experimental details pertaining to elemental (C, H, N) analyses, IR spectra (KBr discs),
1H and 13C NMR, UV-Vis. absorption and photoluminescence spectra are the same as
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described elsewhere [5,7]. For P NMR spectra, PCl3 was used as an external reference (δ =
220 ppm). Pressed pellet room temperature conductivity of the complexes was measured with
an LCR meter PSM 1735, Newton forth LTD, UK.
Crystallography
Single crystal X-ray data for 1-5 were collected on an Oxford Diffraction X-calibur CCD
diffractometer at 293 K using Mo Kα radiation. Data reduction was carried out using the
CrysAlis program [18]. The structures were solved by direct methods using SHELXS-97 [19]
and refined on F2 by the full matrix least squares technique using SHELXL-97 [19]. Non-
hydrogen atoms were refined anisotropically and hydrogen atoms were geometrically fixed
with thermal parameters equivalent to 1.2 times that of the atom to which they were bonded.
2 crystallised with a dichloromethane solvent molecule. Diagrams for all complexes were
prepared using ORTEP [20].

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2.2. Syntheses of complexes
[Cu(PPh3)2L] (L=L1 (1), L2 (2), L3 (3), L4 (4) L5 (5))
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The heteroleptic complexes were synthesized by the following general procedure.
Cu(PPh3)2NO3 (0.650 g, 1 mmol) dissolved in CH2Cl2 (10 ml) was added to a 15 ml MeOH
solution of KL1 (0.302 g, 1 mmol), KL2 (0.217 g, 1 mmol), KL3 (0.276 g, 1 mmol), KL4
(0.212 g, 1 mmol) or KL5 (0.223 g, 1 mmol) separately at room temperature. A yellow-
orange precipitate was formed after a little while. In each case the reaction mixture was
stirred for 5 h and the solid product was collected by filtration, washed with MeOH (2 x 5 ml)
and ether (5 ml), and vacuum-dried. The crude products were recrystallized from a
dichloromethane/methanol mixture, yielding light yellow to orange needle shaped crystals of
compounds 1-5.
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2.2. Characterization data
1. Yield: 0.731 g, 86%. M.p.: 145-147 °C. C48H41CuON2P2S2 (851.4) calcd.: C 67.71, H 4.85,
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N 3.29; found: C 67.52, H 4.73, N 3.17%. IR (KBr, cm-1) ν: 1434 (νC N), 1093 (νC S). H
NMR (300.40 MHz, CDCl3) δ (ppm): 8.49-8.47 (d, 2H, C5H5N) 7.33-7.10 (m, 30H, Ar-H +
2H, C5H5N + 1H, C4H3O), 6.31 (s, 2H, C4H3O) 5.22 (s, 2H, py-CH2-N) 5.21 (s, 2H, furyl-
CH2-N). 13C NMR (75.45 MHz, CDCl3) δ (ppm): 212.14 (CS2), 150.24, 149.76, 122.31
(C5H5N), 146.11, 142.0, 110.44, 109.01 (C4H3O), 134.65, 134.39, 133.80, 133.66, 129.21,
128.26 (C-PPh3), 53.19 (py-CH2-N), 47.28 (C4H3OCH2). 31P NMR (121.50 MHz, CDCl3) δ
(ppm): 1.917. UV-vis (CH2Cl2, λmax/nm, ε/M-1 cm-1): 238 (2.82 x 104), 265 (2.52 x 104). σrt =
1.59 x 10-5 S cm-1.
2. Yield: 0.681 g, 81%. M.p.: 154-157 °C. C42H40Cl2CuNP2S3 (851.31) calcd.: C 59.25, H
4.74, N 1.65; found: C 59.09, H 4.58, N 1.42%. IR (KBr, cm-1) ν: 1433 (νC N), 1091 (νC S).
1H NMR (300.40 MHz, CDCl3) δ (ppm): 7.30-7.16 (m, 30H, Ar-H), 4.37, (t, 4H, NC2H4-),
2.56 (t, 4H, SC2H4-). 13C NMR (75.45 MHz, CDCl3) δ (ppm): 208.33 (CS2), 133.73, 133.20,
129.04, 127.99, 127.91 (C-PPh3), 51.17 (NC2H4-), 26.71 (SC2H4-). 31P NMR (121.50 MHz,
CDCl3) δ (ppm): 1.947. UV-vis (CH2Cl2, λmax/nm, ε /M-1 cm-1): 240 (3.20 x 104), 260 (3.51 x
104), 285 (3.00 x 104), 325 (1.27 x 104). σrt = 2.26x10-7 S cm-1.
3. Yield: 0.709 g, 86%. M.p.: 159-162 °C. C47H43CuN2P2S2 (825.49) calcd.: C 68.39, H 5.25,
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N 3.39; found: C 68.20, H 5.33, N 3.17%. IR (KBr, cm-1) ν: 1433 (νC N), 1094 (νC S). H
NMR (300.40 MHz, CDCl3) δ (ppm): 7.34-6.88 (m, 35H, Ar-H), 4.22 (t, 4H, C2H4-NPh),

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3.15 (t, 4H, C2H4-NCS2). 13C NMR (75.45 MHz, CDCl3) δ (ppm): 208.35 (CS2), 74.41
(OCH2), 150.79, 134.28, 133.78, 133.60 (C6H5-N), 129.26, 129.14, 128.29, 128.19, 120.03
(C-PPh3). 31P NMR (121.50 MHz, CDCl3) δ (ppm): 0.399. UV-vis (CH2Cl2, λmax/nm, ε/M-1
cm-1): 245 (3.61 x 104), 260 (3.63 x 104), 279 (3.53 x 104), 325 (1.25 x 104). σrt = 3.96 x 10-6
S cm-1.
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4. Yield: 0.594 g, 78%. M.p.: 164-166 °C. C42H35CuO2P2S2 (761.30) calcd.: C 66.26, H 4.63;
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found: C 66.03, H 4.69%. IR (KBr, cm-1) ν: 1159 (νC O), 1077 (νC S). H NMR (300.40
MHz, CDCl3) δ (ppm): 7.41-7.18 (m, 30H, Ar-H + 1H, C4H3O), 6.41-6.34 (s, 2H), 5.34 (s,
2H, OCH2). 13C NMR (75.45 MHz, CDCl3) δ (ppm): 226.05 (CS2), 149.41, 142.95, 110.96,
110.46 (C4H3O), 128.40, 129.51, 133.57 (C-PPh3), 59.67 (O-CH2-C4H3O). 31P NMR (121.50
MHz, CDCl3) δ (ppm): 0.536. UV-vis (CH2Cl2, λmax/nm, ε/M-1 cm-1): 240 (3.07 x 104), 265
(2.99 x 104), 320 (8.7 x 103). σrt = 3.37 x 10-8 S cm-1.
5. Yield: 0.648 g, 84%. M.p.: 169-171 °C. C43H36CuONP2S2 (772.33) calcd.: C 66.87, H
4.70, N 1.81; found: C 66.72, H 4.53, N 1.67%. IR (KBr, cm-1) ν: 1146 (νC O), 1038 (νC S).
1H NMR (300.40 MHz, CDCl3) δ (ppm): 8.53-8.54 (d, 2H, C5H5N) 7.70-7.19 (m, 30H, Ar-H
+ 2H, C5H5N), 5.46 (s, 2H, py-CH2-O). 13C NMR (75.45 MHz, CDCl3) δ (ppm): 227.43
(CS2), 63.03 (OCH2), 151.54, 149.71, 121.52 (C5H5N), 137.57, 137.57, 133.70, 130.04,
129.64, 128.47, 128.26 (C-PPh3). 31P NMR (121.50 MHz, CDCl3) δ (ppm): -3.527. UV-vis.
(CH2Cl2, λmax/nm, ε/M-1 cm-1): 238 (2.93 x 104), 265 (2.67 x 104), 320 (8.7 x 103). σrt = 1.98 x
10-7 S cm-1.
3. Results and discussion
3.1. Synthesis comments
The heteroleptic complexes 1-5 were synthesized according to the scheme given in Fig. 1.
3.2. Spectroscopy
The IR spectra of the complexes 1-5 show ν(C–N), ν(C–O) and ν(CS2) frequencies near
1434, 1146-1159 and 1068-1094 cm-1, diagnostic of dithiocarbamate and xanthate ligand
coordination. A significant enhancement in the ν(C–N) frequency of the dithiocarbamate
complexes in comparison to the potassium salts of the ligands KL1-KL3 (1269-1280 cm-1)
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shows the dominant contribution of the canonical form R2N=CS2 , thereby indicating partial
double bond character in the C-N bond (vide infra, X-ray crystallography). In the case of the

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xanthate complexes (4 and 5) the v(C-O) frequency also perceptibly increases because of the
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greater electron delocalisation over the O-CS2 group in the canonical form ROCS2 .
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The H NMR spectra of the complexes 1-5 show the characteristic resonances of the ligand
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functionalities which integrate well to the corresponding hydrogen atoms. The presence of a
doublet at δ ~8.5 ppm and two singlets at δ ~6.3 and 6.4 ppm is due to the pyridine (1 and 5)
and furan (1 and 4) ring protons. In 2, the presence of two triplets at δ 4.37 and 2.56 ppm are
diagnostic of the thiomorpholine ring protons and in 3, the triplets at δ 4.22 and 3.15 ppm
arise due to the piperazine ring protons. In addition to this, all the complexes show a multiplet
in the range δ ~7.4-7.1 ppm for the phenyl ring protons of the PPh3 moiety. In comparison to
the free ligands, there is no perceptible shift in the proton NMR spectra of complexes (ESI).
In the 13C NMR spectra, all the complexes showed a single low field resonance associated
with the NCS2 and OCS2 carbons of the dithiocarbamate and xanthate moieties in the ranges
δ 208-212 and 226-227 ppm, respectively. Notably, because of the dominant contribution of
the R2N+=CS22- resonance form in the dithiocarbamate complexes, the NCS2 carbon is more
shielded than for the free ligands, hence the 13C signal is shifted to higher field in the
complexes as compared to the free ligands (δ = 213.63-214.28 ppm). On the contrary, in the
case of the xanthate complexes, the OCS2 carbon resonance shows a perceptible downfield
shift compared to that found in the free xanthate ligands (δ ~218 ppm) because of the
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significant contribution of the ROCS2 resonance form. The 31P NMR spectrum of the
precursor complex [Cu(PPh3)2NO3] shows a sharp singlet at δ 1.126 ppm. Upon complexation
with the dithio ligands, the singlet observed in the δ -3.527-1.947 ppm region is only slightly
shifted in all the compounds as compared to the precursor, which indicates the equivalent
nature of the PPh3 ligands bonded to the copper atom.
3.3. Crystal structures
Single crystals of 1-5 were obtained by slow evaporation of a solution of the complexes in
dichloromethane layered with methanol. 2 crystallises with one solvent dichloromethane
molecule. In 3 there are two molecules in the asymmetric unit, called A and B. The
crystallographic data and selected interatomic parameters are listed in Tables 1, 2 and S1,
ESI. The crystal structures of representative complexes 1 and 5 are illustrated in Fig. 2 and
complexes 2, 3 and 4 in Fig. S1, ESI. In all the complexes the copper atom is coordinated by
two sulfur atoms of the dithiocarbamate or xanthate ligand and two phosphorous atoms of the
PPh3 ligands. The Cu-S bond lengths in the dithiocarbamate complexes 1, 2 and 3 are in the

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range 2.3887(11)-2.4183(15) Å, significantly shorter than such distances in the xanthate
complexes 4 and 5, 2.4281(10)-2.4507(11) Å. In contrast, there are no such differences in the
Cu-P distances, which range from 2.2295(11) to 2.2692(10) Å. In all the compounds there are
minor, but significant, differences between related bond lengths, but these do not follow any
discernable pattern. In all cases the CuP2S2 core has a distorted tetrahedral coordination
environment due to the constraint imposed by the C(12), S(11), S(13), Cu(1) chelate-ring,
which leads to small S(11)-Cu-S(13) bite angles ranging from 73.96(4) to 75.14(3)o for the
dithioligands, and the steric restrictions of the bulky phosphine ligands. The remaining angles
differ considerably. The P(1)-Cu(1)-P(2) angles of 124.83(5) and 125.85(3)o for 1 and 2
respectively are similar, whereas those for 3, 4 and 5 are smaller with significant variations,
i.e. 122.50(4), 119.36(4)o in 3, 123.71(4) in 4 and 119.34(4) in 5, differences that may be
ascribed to the disposition of the phenyl rings. The P-Cu(1)-S angles vary considerably in all
the structures and fall in the range 100.87(4)-126.31(4)o. The angles between the two least
square planes formed by Cu(1), S(11), S(13) and C(12) and by P(1), Cu(1) and P(2) are
84.5(1), 86.2(1), 82.6(1), 82.3(1), 88.7(1) and 85.1(1)o respectively for complexes 1, 2, 3A,
3B, 4 and 5, thus indicating that the two planes are nearly perpendicular to each other. The
r.m.s. deviations from planarity of the atoms Cu(1), S(11), S(13) and C(12), defining the
chelate rings, are 0.043, 0.013, 0.061, 0.070, 0.024, 0.045 Å respectively for compounds 1-5.
The Cu-P and Cu-S bond distances (Tables 1 and 2) are well within the range of analogous
copper(I) dithiocomplexes [6,7]. In 1-3, the C(12)-N(14) bond lengths of 1.336(7)-1.342(4)
Å, are intermediate between C-N (1.47 Å) and C=N (1.28 Å) bond lengths, thereby indicating
partial double bond character of the C-N bond. The C-S bond lengths of 1.660(4)-1.683(4) Å
in the xanthate complexes (4 and 5) are considerably smaller than those of 1.700(3)-1.721(3)
Å in the dithiocarbamate complexes (1-3), though both are significantly shorter than the C-S
single bond (ca. 1.81 Å) due to π delocalization over the NCS2 backbone. All the complexes
lack any prominent SꢀꢀꢀS intermolecular stacking of the coordinated dithiocarbamate and
xanthate ligands, often found in dithiocomplexes, because of the steric bulk of the phosphine
ligands.
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3.4. Electronic absorption and emission spectra
Complexes 1-5 show very similar absorption features at ~ 240 nm (ε = 28,200 – 36,100 M-1
cm-1) and 265-275 nm (ε = 25,200 - 36,300 M-1 cm-1) characteristic of metal perturbed π - π*
ILCT transitions of the dithiocarbamate/xanthate and PPh3 ligands [13]. An absorption
shoulder at ~325 nm (ε = 8,700 - 12,700 M-1 cm-1) can be assigned to some admixture of

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ILCT/LLCT [11] and metal-to-ligand charge transfer (MLCT) states (Fig. 3). The observed
absorption bands of 1 and 5 have been explained with the help of TD-DFT calculations. The
calculated vertical excitation energies, oscillator strengths, composition and tentative nature
of the transitions for 1 and 5 obtained at the TD-DFT level have been listed in Tables S2 and
S3, ESI. The selected HOMOs and LUMOs involved in the transitions for 1 and 5 are shown
in Figs. S3 and S4, ESI respectively.
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65
When excited at 270 nm in CH2Cl2 solution at room temperature, 1-5 show unstructured
bands at ~ 330 and ~ 480 nm (Figs. 4 and S2, ESI), arising from the admixture of ILCT and
MLCT states of the metal dithio-PPh3 ligands coordination environments [7a,13]. The
emission spectra as well as corresponding excitation spectra for 1 are displayed in Fig. 4 and
for 2-5 in Fig. S2, ESI. In each case, the excitation spectrum displayed one maxima at 270
nm. It is clear from the TD-DFT results of 1 and 5, the band near 270 nm is due to ILCT with
some admixture of MLCT in the electronic absorption (Tables S2 and S3, ESI). The bulky
substituents on these dithio ligands together with the PPh3 ligands may force minimal
structural reorganisation of the complexes in the excited state as compared to the ground
state, i.e. structural distortion from a tetrahedral to a flattened structure reported in the
copper(I), d10 complexes, influencing the luminescent characteristics after MLCT excitation
[12,15].
3.5. Second order NLO activity
Asymmetric molecules that show polarization induced by donor and accepter groups in pi-
electron conjugated molecules are potential candidates for electro-optic and NLO
applications. In order to investigate the second order NLO activity, we have performed DFT
calculations for 1-5. The values of βtot of the first hyperpolarizability for 1-5 are 4.736, 2.596,
2.069, 1.305 and 6.393 x 10-30 esu respectively. The values for 1 and 5 are of a higher order
of magnitude due to greater charge transfer from the electron rich pyridine moiety in these
complexes [7b] (for details, see ESI).
3.6. Electrical conductivity
The conductivities of complexes 1-5 have been measured using complex impedance
spectroscopy with powdered samples as pressed pellets sandwiched by silver electrodes
(diameter: 11.4 for 1 and 3, 11.2 mm for 2, 4 and 5; with a the pellet thickness of 1.7 (1), 1.3
(2), 1.5 (3), 1.1 (4) and 1.1 mm (5)). All the complexes are weakly conducting (σrt = 1.59 x

1
2
3
4
5
6
10-5 - 3.37 x 10-8 S cm-1) due to weak intermolecular SꢀꢀꢀS interactions in the solid state (X-
ray structures, vide supra), which are hindered by the bulky phosphine ligands.
7
8
9
4. Conclusions
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The new heteroleptic copper(I) dithiocarbamate/xanthate-PPh3 complexes 1-5 have been
synthesized and fully characterised by microanalysis and X-ray crystallography. All the
complexes have a distorted tetrahedral geometry with a CuP2S2 core. Notably, all the
complexes are mononuclear; the dimerization observed in the analogous Cu(I)
dithiocarbamate/xanthate-PR3(R= Me, OMe, Et) complexes [6a] is prevented in 1-5,
presumably due to the bulkiness of the PPh3 ligands. TD-DFT calculations provide good
agreement between the experimental and calculated electronic absorption bands of 1 and 5.
The theeoretical calculations indicate second order non-linear optical behaviour, and
significantly 1 and 5 present good non-linear optical activity due to the presence of a pyridyl
substituent on the N/O atom of the dithio backbone. The complexes 1-5 are intensely
luminescent in CH2Cl2 solution at room temperature, originating from an admixture of ILCT
and MLCT states. All the complexes are weakly conducting at room temperature due to a
lack of prominent SꢀꢀꢀS/CuꢀꢀꢀS intermolecular associations in the solid state. An exploration of
these type of complexes, with functionalized dithiolates and different phosphine ligands, may
be useful for their possible application as luminescent materials.
Appendix A. Supplementary data
CCDC 983940-983944 contain the supplementary crystallographic data for 1-5. These data
can be obtained free of charge via http:// www.ccdc.cam.ac.uk/conts/retrieving.html, or from
the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax:
(+44) 1223-336-033; or e-mail: deposit@ccdc.cam.ac.uk.
Acknowledgements
We gratefully acknowledge the Council of Scientific and Industrial Research (CSIR), New
Delhi for financial assistance (NS), Project No. 01(2679)/12/EMR-II, the University Grant
Commission (UGC) for SRF (ANG) and the Department of Chemistry, Banaras Hindu
University for the Oxford diffraction X-calibur CCD diffractometer.

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5
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1
2
3
4
5
Figure captions:
Fig. 1. (a) General methodology for the synthesis of the complexes. (b) The dithiocarbamate
and xanthate salts used in this work.
6
7
8
9
Fig. 2. Ortep diagrams of 1 and 5 at the 30% probability level.
Fig. 3. UV-Vis spectra of 1-5 in CH2Cl2 at room temperature
Fig. 4. (a) Emission spectrum of 1 at room temperature (λem.= 320 and 486 nm) upon
excitation at 270 nm. (b) Excitation spectra of 1 (λex.= 486 nm).
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Table captions:
Table 1. Selected bond lengths [Å] in the structures.
Table 2. Selected bond angles [°] in the structures.
Table 1.Selected bond lengths [Å] in the structures.
Bond
1(X=N)
2(X=N)
2.2647(8)
2.2554(8)
2.4065(8)
2.3808(8)
1.721(3)
3A (X=N) 3B(X=N)
4(X=O)
5(X=O)
Lengths
Cu(1)-P(1)
2.2501(14)
2.2611(14)
2.3992(14)
2.4185(15)
1.704(5)
2.2660(10)
2.2701(10)
2.2349(11)
2.4054(11)
2.3887(11)
1.704(4)
2.2625(11) 2.2692(10)
2.2631(11) 2.2390(10)
2.4340(12) 2.4288(11)
2.4455(12) 2.4504(12)
2.2295(11)
2.4169(10)
2.3957(11)
1.715(4)
Cu(1)-P(2)
Cu(1)-S(11)
Cu(1)-S(13)
S(11)-C(12)
S(13)-C(12)
X(14)-C(12)
1.668(4)
1.680(4)
1.351(5)
1.660(4)
1.683(4)
1.358(4)
1.713(5)
1.700(3)
1.707(4)
1.709(4)
1.336(7)
1.342(4)
1.336(4)
1.340(4)
Table 2. Selected bond angles [°] in the structures.
Bond Angles
1
2
3A
3B
4
5
124.83(5)
125.85(3)
122.50(4)
119.36(4)
123.71(4) 119.34(4)
P(1)-Cu(1)-P(2)

1
2
3
4
5
6
7
8
116.54(5)
112.32(5)
103.98(5)
74.87(5)
113.89(3)
113.39(3)
112.19(3)
75.14(3)
113.88(4)
108.32(4)
126.31(4)
74.76(3)
115.93(4)
113.96(4)
121.78(4)
75.03(4)
110.25(4) 119.00(4)
109.71(4) 109.11(4)
112.63(4) 123.38(4)
P(2)-Cu(1)-S(13)
P(1)-Cu(1)-S(13)
P(2)-Cu(1)-S(11)
S(13)-Cu(1)-S(11)
P(1)-Cu(1)-S(11)
S(13)-C(12)-S(11)
C(12)-S(11)-Cu(1)
C(12)-S(13)-Cu(1)
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73.96(4)
74.11(4)
112.16(5)
117.9(3)
104.05(3)
117.13(17)
83.23(10)
84.46(10)
100.87(4)
117.3(2)
102.46(4)
117.6(2)
115.40(4) 102.96(4)
122.4(2)
123.2(2)
83.14(17)
83.56(18)
83.08(13)
83.88(13)
82.77(13)
83.20(13)
82.00(14) 81.61(14)
81.43(14) 80.53(14)

Figures Files for
Syntheses, Crystal Structures and Optical Properties of Heteroleptic
Copper(I) Dithio/PPh3 Complexes
Ajit N. Guptaa, Vikram Singha, Vinod Kumara, Lal Bahadur Prasada, Michael G. B.
Drewb and Nanhai Singh*a
a Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi 221005, India
Fax: +91-542-2386127, E-mail: nsingh@bhu.ac.in, nsinghbhu@gmail.com
b Department of Chemistry, University of Reading, Whiteknights, Reading, RG6 6AD (U.K.)
CH2Cl2 / CH3OH
[Cu(PPh3)2L]
[Cu(PPh3)2NO3] + KL
rt,
- KNO3
1-5
L= L1 (1), L2 (2), L3 (3), L4 (4), L5 (5)
(a)
N
S
S
S
S
S
N
N
N
O
S
Ph
N
S
L2
L1
L3
S
S
O
O
S
O
N
S
L4
L5
(b)
Fig. 1. (a) General methodology for the synthesis of the complexes. (b) The dithiocarbamate
and xanthate ligands used in this work.

1
5
Fig. 2. Ortep diagrams of 1 and 5 at the 30% probability level.
3.5
1
2
3.0
2.5
2.0
1.5
1.0
0.5
0.0
3
4
5
250
300
 (nm)
350
400
Fig. 3. UV-Vis spectra of 1-5 in CH2Cl2 at room temperature

400
300
200
100
0
a
b
250
300
350
400
nm
450
500
Fig. 4. (a) Emission spectrum of 1 at room temperature (λem.= 320 and 486 nm) upon
excitation at 270 nm (b) Excitation spectrum of 1 (λex.= 486 nm).

Five new heteroleptic Cu(I) dithiocarbamate/xanthate-PPh3 complexes (1-5) have been
synthesized and fully characterized, and their conducting, non-linear optical and
luminescence properties investigated. All the complexes are intensely luminescent in CH2Cl2
solution at room temperature.