Versatile coordination environment and interplay of metal assisted secondary interactions in the organization of supramolecular motifs in new Hg(II)/PhHg(II) dithiolates

Article abstract of DOI:10.1016/j.poly.2013.12.005

New mercury(II) complexes of the form [PhHg(L)] (L = L1 (1), L2 (2), L3′ (3), L4 = (4)); [Hg(L)₂] (L = L5 (5), L4 (7) and [Hg ₂(L6)₄] (6) have been synthesized and characterized by micro analysis and X-ray crystallography. Both 1 and 2 are linear; complex 2 revealed intramolecular Hga?O bonding interactions. Complex 3 possesses T-shaped geometry in a linear polymeric chain motif. Although serendipitously formed, 3 is the first example of a metal trithioxanthate complex. 4 is a typical dimer and in 5, a helical chain motif is generated via Hga?S contacts. 6 is a dinuclear complex with distorted square pyramidal geometry. 7 is mononuclear with a tetrahedrally coordinated mercury(II) ion. All complexes are luminescent in solution and solid state. In 2 the nature of Hga?O interactions have been assessed by DFT calculations and the electronic transitions in 3 have been corroborated by TDDFT calculations.

Full text of DOI:10.1016/j.poly.2013.12.005

Polyhedron 69 (2014) 225–233
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Versatile coordination environment and interplay of metal assisted
secondary interactions in the organization of supramolecular motifs
in new Hg(II)/PhHg(II) dithiolates
Gunjan Rajput a, Manoj Kumar Yadav a, Tejender S. Thakur b, Michael G.B. Drew c, Nanhai Singh a,
⇑
a Department of Chemistry, Faculty of Science, Banaras Hindu University, Varanasi 221005, India
b Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, B.S. 10/1, Sector-10, Janakipuram Extension, Sitapur road, Lucknow 226021, India
c 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
New mercury(II) complexes of the form [PhHg(L)] (L = L1 (1), L2 (2), L30 (3), L4 = (4)); [Hg(L)2] (L = L5 (5),
L4 (7) and [Hg2(L6)4] (6) have been synthesized and characterized by micro analysis and X-ray crystal-
lography. Both 1 and 2 are linear; complex 2 revealed intramolecular Hgꢀ ꢀ ꢀO bonding interactions. Com-
plex 3 possesses T-shaped geometry in a linear polymeric chain motif. Although serendipitously formed,
3 is the first example of a metal trithioxanthate complex. 4 is a typical dimer and in 5, a helical chain
motif is generated via Hgꢀ ꢀ ꢀS contacts. 6 is a dinuclear complex with distorted square pyramidal geom-
etry. 7 is mononuclear with a tetrahedrally coordinated mercury(II) ion. All complexes are luminescent in
solution and solid state. In 2 the nature of Hgꢀ ꢀ ꢀO interactions have been assessed by DFT calculations and
the electronic transitions in 3 have been corroborated by TDDFT calculations.
Article history:
Received 1 November 2013
Accepted 6 December 2013
Available online 12 December 2013
Keywords:
Dithiocarbamate
Xanthate
Trithioxanthate
Photoluminescence
Theoretical calculations
Ó 2013 Elsevier Ltd. All rights reserved.
1. Introduction
bond lengths. Albeit, the preferred coordination geometry of mer-
cury(II) is linear however higher coordination numbers up to six
Transition metal 1,1 dithiolates including those of group 12
metals (Zn, Cd, Hg) have been extensively studied because of their
structural versatility [1–4], molecular electrical conducting and
optical properties, utility as precursors in metal organic chemical
vapour deposition (MOCVD) for the preparation of metal sulphides
as semiconducting materials with useful optical properties and
widespread industrial applications as rubber vulcanization acceler-
ators, oil lubricants and fungicides and pesticides [1–2,5]. The
strong affinity of mercury(II) and organomercurials towards dis-
tinctly soft sulphur donor atoms makes them useful for the detox-
ification of mercury in biological processes and as scavengers from
globally distributed waste products [6]. Mercury(II) chemistry has
been dominated by the sulphur based ligands including those of
the ubiquitous dithiocarbamates and even xanthates. These ligands
have been found extremely versatile for metal-directed self assem-
bly forming supramolecular architectures [2,7]. The Lewis acidity,
high polarizability of mercury(II) ion, satiation of maximum coor-
dination numbers, steric bulk on the pendant groups of the ligands
and the crystal packing effects have demonstrated the crucial role
of sulphur ligands as supramolecular synthons in homo- and het-
eroleptic mercury(II) complexes [8], often with a wide range of
are also exhibited [8]. The luminescent transition metal complexes
including those with closed shell, d10 cations are of growing impor-
tance because of their potential applications as luminescent mate-
rials, LEDs, biological probes and sensors [9].
The dithiocarbamate and xanthate ligands despite some obvi-
ous resemblances differ significantly with regard to their dominant
canonical structures Fig. 1 which contribute significantly to the
overall description of structure and electronic properties of their
complexes.
Many mercury(II) dithiocarbamates and even xanthates are
known [2,7f]. Until recently the analogous organomercury(II)
dithio compounds have not been well established [2e,10,11a]. In
general the dithiocarbamate and xanthate ligands exhibit S,S
chelating behaviour. Recently the bonding features and the lumi-
nescent properties of the novel pyridyl functionalized dithiocarba-
mate ligand complexes exhibiting interesting intermolecular
Hgꢀ ꢀ ꢀN bonding interactions have been explored [11]. Given this
versatility and lack of exploration of pyridyl functionalized dithio-
carbamate ligand, in order to gain more insight into the fascinating
coordination patterns and properties, in this work we present the
synthesis, crystal structures and luminescent properties of new
mercury(II) and phenylmercury(II) compounds of the xanthate
and dithiocarbamate ligands with varying pendant groups such
as naphthyl, N-methyl-pyrrole and 3-pyridyl on the CS2 backbone
⇑
Corresponding author. Tel.: +91 542 2307321; fax: +91 542 2386127.
E-mail addresses: nsingh@bhu.ac.in, nsinghbhu@gmail.com (N. Singh).
0277-5387/$ - see front matter Ó 2013 Elsevier Ltd. All rights reserved.
http://dx.doi.org/10.1016/j.poly.2013.12.005

226
G. Rajput et al. / Polyhedron 69 (2014) 225–233
iso-amylxanthate (KL1), benzylxanthate (KL2), n-propylxanthate
(KL3), N-(N-methyl-2-pyrrole)-N-(methyl-3-pyridyl)dithiocarba-
mate (KL4), 1-benzyl-4-hydroxypiperidinexanthate (KL5) and
N-methylnaphthyl-N-(methyl-3-pyridyl)dithiocarbamate
(KL6)
were prepared according to literature procedures [11] by the reac-
tion of the appropriate alcohol or secondary amine with CS2 and
KOH.
The experimental details pertaining to elemental analyses (C, H,
N, S) and recording of IR(KBr), 1H and 13C{1H} NMR and UV–Vis.
spectra in CH2Cl2 and as Nujol mull are the same as described ear-
lier [11]. The photoluminescent spectra in CH2Cl2 solution and so-
lid state and the quantum yield measurements were performed at
room temperature using a Fluorolog Horiba Jobin Yvon spectro-
photometer. Sodium salicylate was used as the standard phosphor
for the quantum yield determinations. The overall quantum yields
Fig. 1. Dominant canonical form of xanthate and dithiocarbamate ligands.
of these ligands. The most important aspect of this work was to
investigate the implications of various functional groups on the
dithio backbone in deciding the mercury(II) coordination sphere,
non-covalent interactions including those involving the metal
centre in the construction of varied supramolecular architectures
owing to the fact that the field of sulphur donor coordination poly-
mers is less explored [10e]. Furthermore, by contrast to the well
known trithiocarboxylate [12a–c] complexes and rarely reported
trithiocarbamates [12d,e] that play an important role in the rubber
vulcanization process [12f], for the first time the trithioxanthate
complex of PhHg(II) has been isolated and structurally character-
ized. The luminescent characteristics of the compounds have been
correlated with their structures. In order to assess the nature of
Hgꢀ ꢀ ꢀO bonding interactions DFT calculations on 1 and 2 have been
performed. TDDFT calculations were performed on 3 to support the
electronic transitions observed in this complex. The results of these
investigations are described here.
(Uoverall) were measured following the protocol described by Bril
and co-workers [13] and calculations were done according to the
following expression:
Uoverall ¼ fUstð1 ꢁ RstÞðAcÞg=fð1 ꢁ RcÞðAstÞg
where Rc and Rst represent the diffuse reflectance of the coordina-
tion complex and of the standard phosphor respectively at a fixed
wavelength. Ust represents the quantum yield of the standard phos-
phor. The terms Ac and Ast represent the area under the complex
and the standard phosphor emission spectra respectively.
2.2. Synthesis of the compounds
2. Experimental
The compounds were prepared adopting similar procedures as
given below.
2.1. Materials and methods
All reactionswere carried out in theopen atambient temperature
and pressure. The metal salts Hg(CO2CH3)2 and C6H5Hg(CO2CH3)
and chemicals such as carbon disulfide, 1-naphthaldehyde,
C6H5CH2OH, (CH3)2CHCH2CH2OH, CH3CH2CH2OH; 1-benzyl-4-hy-
droxy piperidine, 3-picolylamine and N-methyl-2-pyrrolecarboxal-
dehyde were purchased from SD Fine Chemicals, India and Sigma
Aldrich respectively and used without further purification. The sol-
vents were distilled according to standard procedures. Potassium
salts of the xanthate and dithiocarbamate ligands Fig. 2 i.e.
2.3. [PhHg(L1)] (1)
To a (10 mL) stirred methanolic solution of the ligand KL1
(0.101 g, 0.5 mmol) was added slowly
a 10 mL solution of
PhHg(CO2CH3) (0.168 g, 0.5 mmol) in the same solvent. The reac-
tion mixture was then stirred for about 3 h at room temperature.
The greenish yellow solid thus formed was filtered off and washed
with methanol followed by diethylether. The crude product was
dissolved in acetone and filtered to discard any undissolved
residue and the clear solution was kept for crystallization. Thin
plate-like colourless crystals were obtained within 2–3 weeks.
Yield: (0.154 g, 70%). Anal. Calc. for C12H16HgOS2 (440.98): C,
32.65; H, 3.66; S, 14.50. Found: C, 32.42; H, 3.75; S; 14.18%. IR
(KBr, cmꢁ1): 1234 ( C–S). 1H NMR (300.40 MHz, CDCl3,
mC–O), 1027 (m
ppm): d 0.98, 0.96 (d, J = 6, 6H, (CH3)2), 1.55–1.75 (m, 1H, –CH–),
1.75, 1.73, 1.71, 1.70 (q, J = 6.00 Hz, 2H, –CH2–), 4.55, 4.53, 4.51
(t, J = 6.00 Hz, 2H, –O–CH2–), 7.39–7.25 (m, 5H, C6H5). 13C
{1H}NMR (75.45 MHz, CDCl3, ppm) d 22.43 (Me), 25.06 (–CH–),
36.85 (–CH2–), 74.63 (–CH2–O–), 128.93, 129.02, 136.86, 154.56
(C6H5), 223.88 (–OCS2). UV–Vis. (CH2Cl2, kmax (nm),
e
(Mꢁ1 cmꢁ1)):
297 (1.8 ꢂ 104).
2.4. [PhHg(L2)] (2)
Colourless crystals of compound 2 were prepared and isolated
following the procedure similar to 1 but using KL2 (0.117 g,
0.5 mmol). Yield: (0.166 g, 72%). Anal. Calc. for
(460.97): C, 36.48; H, 2.62; S, 13.91. Found: C, 36.22; H, 2.70; S,
13.56%. IR (KBr, cmꢁ1): 1262 C–S). 1H NMR
C–O), 1041
C14H12HgOS2
(
m
(m
(300.40 MHz, CDCl3, ppm): d 5.50 (s, 2H, –CH2–O–), 7.44–7.21
(m, 10H, Ar–CH). 13C{1H}NMR (75.45 MHz, CDCl3, ppm) d 75.76
(–CH2–O–), 156.60–126.43 (Ar–C), 221.72 (–OCS2). UV–Vis.
Fig. 2. Structure of the ligands used in present study.
(CH2Cl2, kmax (nm),
e
(Mꢁ1 cmꢁ1)): 297 (1.67 ꢂ 104).

G. Rajput et al. / Polyhedron 69 (2014) 225–233
227
2.5. [PhHg(L3)] (3)
1H NMR (300.40 MHz, CDCl3, ppm): d 3.60 (s, 3H, –CH3), 4.97 (s,
2H, –CH2–C4H3N–CH3), 5.05 (s, 2H, –CH2–C6H4N), 7.26, 6.60, 6.08
(s, 3H, –C4H3N–CH3), 8.55–7.28 (m, 4H, C5H4N). 13C{1H}NMR
(75.45 MHz, CDCl3, ppm) d 34.61 (CH3–NC4H3), 51.43 (–CH2–
C4H3N–CH3), 53.80 (–CH2–C5H4N), 149.48–107.74 (Ar–C), 206.46
Colourless crystals of compound 3 were prepared and isolated
following the procedure similar to 1 but using KL3 (0.093 g,
0.5 mmol). Yield: (0.160 g, 72%). Anal. Calc. for
(445.00): C, 26.99; H, 2.72; S, 21.62. Found: C, 26.59; H, 2.83; S,
C–O), 1044
21.47%. IR (KBr, cmꢁ1): 1262 C–S). 1H NMR
(300.40 MHz, CDCl3, ppm): d 1.04, 1.01, 0.99 (t, J = 9.01 Hz, 3H,
CH3–), 1.88–1.55 (m, 2H, –CH2–), 4.47, 4.45, 4.43 (t, J = 6.00 Hz,
2H, –CH2–O–), 7.44–7.25 (m, 5H, C6H5). 13C{1H}NMR (75.45 MHz,
CDCl3) d 10.39 (CH3), 21.67 (–CH2–), 77.42–76.57 (merged with
CDCl3 peaks, –CH2–O–), 154.54, 136.85, 129.01, 128.92 (C6H5),
C10H12HgOS3
(–NCS2). UV–Vis. (CH2Cl2, kmax (nm),
e
(Mꢁ1 cmꢁ1)): 275
(
m
(m
(6.3 ꢂ 104).
2.10. Crystallization and X-ray crystal structure determinations
Single crystals were obtained by slow evaporation of solutions
of the products 1–3 and 5 in acetone and 4, 6 and 7 in CH2Cl2 solu-
tion. Apart from a little black residue of mercuric sulphide no other
crystalline by-product was found within the crystalline sample of
3. Single crystal X-ray diffraction data for 1–7 were collected on
223.98 (–OCS2). UV–Vis. (CH2Cl2, kmax (nm),
e
(Mꢁ1 cmꢁ1)): 298
(0.68 ꢂ 104).
2.6. [PhHg(L4)] (4)
an Oxford X-calibur CCD diffractometer at 293 K using Mo Ka radi-
ation. Data reduction for 1–7 was carried out using the CrysAlis
program [14]. The structures were solved by direct methods using
SHELXS-97 [15] and refined on F2 by full matrix least squares method
using SHELXL-97 [16]. Non- hydrogen atoms were refined anisotrop-
ically and hydrogen atoms were geometrically fixed with thermal
parameters equivalent to 1.2 times that of the atom to which they
were bonded. Diagrams for all complexes were prepared using OR-
TEP [17], Diamond and Mercury software.
Pale yellow crystals of 4 were obtained and isolated following
the procedure similar to 1 but using KL4 (0.156 g, 0.5 mmol). The
crystals were grown in CH2Cl2. Yield: (0.216 g, 78%). Anal. Calc.
for C38H38Hg2N6S4 (1108.16): C, 41.18; H, 3.42; N, 7.58; S, 11.55.
Found: C, 41.03; H, 3.35; N, 7.59; S, 11.224%. IR (KBr, cmꢁ1):
1280 (mC–O), 1040 (m
C–S). 1H NMR (300.40 MHz, CDCl3, ppm): d
3.58 (s, 3H, –CH3), 5.01(s, 2H, –CH2–C4H3N–CH3), 5.10 (s, 2H, –
CH2–C6H4N), 7.25, 6.60, 6.08 (s, 3H, –C4H3N–CH3), 8.54–7.26
(m, 4H, C5H4N). 13C{1H}NMR (75.45 MHz, CDCl3, ppm) d 34.38
(CH3–NC4H3), 49.90 (–CH2–C4H3N–CH3), 52.61 (–CH2–C5H4N),
154.01–107.50 (Ar–C), 205.13 (–NCS2). UV–Vis. (CH2Cl2, kmax
2.11. Computational methods
(nm),
e
(Mꢁ1 cmꢁ1)): 255 (2.8 ꢂ 104), 303 (1.00 ꢂ 104).
All calculations were performed by the density functional the-
ory (DFT) methodology using the GAUSSIAN 09 software suite [18].
The ground state energy calculations for complexes 1–3 were per-
formed using the Truhlar’s M06–2X Global-hybrid-meta-GGA
functional. A mixed basis set approach was followed in all the
calculations. The Hg atom is treated with LANL2DZ (Los Alamos
National Laboratory 2 Double-Zeta), a ECP type basis set, the
aug-cc-pVDZ basis set for S, O, N and the cc-pVDZ basis set were
used for C and H-atoms. Input geometries used in the calculations
were obtained from X-ray diffraction data. The neutron normalized
H-atom coordinates were used for complexes 1 and 2. Electronic
excited state calculations on 3 were performed using the Time-
Dependent Density Functional Theory (TDDFT) in solution
(solvent = dichloromethane) using the PCM model and five differ-
ent functionals at the mixed basis set described above.
2.7. [Hg(L5)2] (5)
Pale yellow crystals of compound 5 were obtained and isolated
following the procedure similar to 1 but using KL5 (0.160 g,
0.5 mmol) and HgCl2 (0.070 g, 0.25 mmol). Yield: (0.138 g, 75%).
Anal. Calc. for C26H32HgN2O2S4 (733.41): C, 42.57; H, 4.36; N,
3.82; S, 17.45. Found: C, 42.27; H, 4.39; N, 3.64; S, 17.15%. IR
(KBr, cmꢁ1): 1405 ( C–S). 1H NMR (300.40 MHz, CDCl3,
mC–N), 1023 (m
ppm): d 1.62–2.69 (m, 8H, NC4H8CH–O), 3.52 (s, 2H, CH2–NC5H9),
5.20, 5.18, 5.17 (t, J = 6.00 Hz, 1H, –O–CH–C4H8N), 7.32–7.24
(m, 5H, C6H5). 13C{1H}NMR (75.45 MHz, CDCl3, ppm) d 50.00,
30.16 (C5H9N), 62.86 (–CH2–NC5H9), 84.42 (–O–CH–C4H8N),
138.19–127.11 (C6H5), 221.44 (–OCS2). UV–Vis. (CH2Cl2, kmax
(nm),
e
(Mꢁ1 cmꢁ1)): 276 (2.30 ꢂ 104).
2.8. [Hg2(L6)4] (6)
3. Results and discussion
Yellow crystals of compound 6 were obtained and isolated fol-
The homo- and heteroleptic Hg(II)/PhHg(II) complexes have
been isolated by the treatment of a methanolic solution of Hg
(CO2CH3)2 or PhHg(CO2CH3) with the potassium salt of the ligands
(KL1–KL6) in required molar ratios Scheme 1. Notably the reaction
of PhHg(CO2CH3) with n-propylxanthate (L3) serendipitously
yielded a trithioxanthate complex 3 in good yield by self-assembly
with a phenylmercury acetate salt, to the best of our knowledge
not reported earlier. The complexes are air-stable and are soluble
in common organic solvents such as CH2Cl2 and CHCl3. They have
been characterized by elemental analysis, IR, NMR, UV–Vis. spectra
and single crystal X-ray diffraction. An investigation of their X-ray
structures revealed varied coordination geometries and diverse
structural patterns due to bonding interactions involving the metal
ions. The significance of secondary interactions involved in the
construction of supramolecular structures has been supported by
theoretical calculations on 1 and 2. The pertinent electronic transi-
tions in 3 have been corroborated by TDDFT calculations. The lumi-
nescent properties of the complexes have been correlated with
their solid state structures.
lowing the procedure similar to
4 but using KL6 (0.187 g,
0.5 mmol) and Hg(OAc)2 (0.080 g, 0.25 mmol). Yield: (0.172 g,
80%). Anal. Calc. for C73H64Hg2N8OS8 (1727.06): C, 50.76; H, 3.71;
N, 6.48; S, 14.82. Found: C, 50.58; H, 3.68; N, 6.22; S, 14.48%. IR
(KBr, cmꢁ1): 1412 ( C–S). 1H NMR (300.40 MHz, CDCl3,
mC–N), 1089 (m
ppm): d 5.50 (s, 2H, –CH2–C10H7), 5.00 (s, 2H, –CH2–C5H4N),
7.25–8.54 (m, 11H, Ar–H). 13C{1H}NMR (75.45 MHz, CDCl3, ppm)
d 55.60 (–CH2–C10H7), 57.27 (–CH2–C5H4N), 149.46–122.90 (Ar–
C), 207.80 (–NCS2). UV–Vis. (CH2Cl2, kmax (nm),
e
(Mꢁ1 cmꢁ1)):
243 (6.5 ꢂ 104), 282 (7.70 ꢂ 104).
2.9. [Hg(L4)2] (7)
Yellow crystals of compound 7 were obtained and isolated fol-
lowing the procedure similar to but using KL4 (0.156 g,
6
0.5 mmol). Yield: (0.146 g, 78%). Anal. Calc. for C26H28HgN6S4
(753.41): C, 41.44; H, 3.71; N, 11.15; S, 16.99. Found: C, 41.26; H,
3.80; N, 10.84; S, 16.62%. IR (KBr, cmꢁ1): 1418 (
mC–N), 1024 (mC–S).

228
G. Rajput et al. / Polyhedron 69 (2014) 225–233
Scheme 1. (a) General methodology for the synthesis of complexes (1–7); (b) In situ generated n-propyltrithioxanthate ligand L3’.
All the complexes show m(C–N), m(C–O) and m(C–S) vibrations diag-
within this category were in clearly defined coordination sites
[2a,10e,20].
nostic of coordinated dithiocarbamate and xanthate ligands. Par-
ticularly a significant enhancement in the m(C-N) frequency of the
complexes in comparison to the free dithiocarbamate ligands indi-
cates the dominant contribution of the canonical form Fig. 1 in the
overall description of the structures of dithiocarbamate and xan-
thate complexes. 1H NMR of all the complexes exhibit resonances
characteristic of the functional groups of the ligands. All the com-
plexes show a single downfield resonance in the d 210–223 ppm
range characteristic of CS2 unit of the dithioligands.
The structure of 1 is a typical 2-coordinate monomeric complex
of Hg(II) in which the metal is bonded to the ipso-carbon atom of
the phenyl ring at 2.066(17) Å and the S11 atom of the xanthate li-
gand L1 at 2.366(4) Å with the C31–Hg1–S11 angle of 178.40(4)°
indicating linear geometry Fig. 3a. The S13 atom is at 3.114(4) Å
from the metal atom of Hg(II). The orientation of the bulky iso-
amyl alkyl chain on the OCS2 backbone favours supramolecular
stabilization via intermolecular C–Hꢀ ꢀ ꢀ
p interactions (3.24 Å)
rather than through Hgꢀ ꢀ ꢀS interactions, prevalent in the organo-
mercury xanthates [2a,e].
The coordination geometry about Hg atom in 2 is similar to that
observed in 1 being two-coordinate with a linear geometry being
bonded to the ipso-carbon atom C31 of the phenyl ring at
2.042(9) Å together with S11 of ligand L2 at 2.386(2) Å. The C31–
Hg1–S11 angle is 175.5(3)°. There is one novel feature of the struc-
ture in that the conformation of the ligand is such that it is O14
rather than S13 that is closest to the metal as indicated by the
Hg1–S11–C12–O14 torsion angle of 12.4(4)°. However the
Hg1ꢀ ꢀ ꢀO14 distance of 2.894(8) Å can only be indicative of a weak
interaction although it is significantly smaller than the sum of the
van der Waals radii [2a,19] for Hg (1.71 Å) and O (1.52 Å) Fig. 4a.
These Hgꢀ ꢀ ꢀO interactions are less favoured, as is indicated by the
hard- soft acid -base (HSAB) concept because the oxygen is a hard
donor whereas the PhHg(II)/Hg(II) ion is a distinctly soft acid but
3.1. Crystal structures
Crystallographic data and structure refinement details are pre-
sented in Table 1. Selected bond distances and angles for 1–4
and 5–7 are provided in the ESI, Tables S1 and S2, respectively.
Their ORTEP diagrams are given in ESI, Fig. S1. All weak interaction
parameters have been listed in Table S3, ESI. All seven complexes
contain a crystallographic centre of symmetry. Each asymmetric
unit contains a single discrete molecule; complex 6 contains a sol-
vent methanol molecule in the asymmetric unit. There is some de-
bate about the distance limit for a Hg–S bonding distance,
particularly as there is so much variation [20]. In the description
of structures that follow, we have fixed the limit at 3.0 Å and found
on inspection that this restriction was appropriate as all bonds
Table 1
Crystal data and refinement parameters for complexes 1–7.
Compound
1
2
3
4
5
6
7
Chemical formula
Formula weight
Crystal system
Space group
a(Å)
C
12H16HgOS2
C14H12HgOS2
460.97
monoclinic
P21/c
15.1541(6)
8.1463(3)
11.6168(5)
(90)
97.454(3)
(90)
1421.97(10)
4
C10H12HgOS3
444.97
monoclinic
P21/c
13.6902(16)
8.1303(12)
10.9444(17)
(90)
96.096(12)
(90)
1211.3(3)
4
C38H38Hg2N6S4 C26 H32 Hg N2 O2 S4 C73H64Hg2N8O S8 C26H28HgN6S4
440.96
monoclinic
P21/c
15.020(5)
5.6389(2)
17.888(6)
(90)
104.28(4)
(90)
1468.2(9)
4
1108.20
triclinic
P1
733.37
monoclinic
C2/c
1727.06
triclinic
P1
753.37
triclinic
ꢀ
ꢀ
ꢀ
P1
8.709(2)
10.615(2)
11.133(3)
69.48(2)
85.255(19)
80.711(19)
950.9(4)
1
39.384(3)
6.3017(3)
24.8682(16)
(90)
110.488(8)
(90)
11.2835(7)
11.8933(7
13.8094(9)
74.797(5)
79.823(5)
85.869(5)
1759.56(19)
1
7.8970(6)
10.7825(10)
16.9660(13)
96.704(7)
92.145(6)
95.664(7)
1426.0(2)
2
b (Å)
c (Å)
a
(°)
b (°)
c
(°)
V (Å3)
5781.6(7)
8
Z
Dcalc (g cmꢁ3
)
1.995
2.097
2.440
1.932
1.685
1.630
1.755
T (K)
293(2)
10.746
832
293(2)
11.098
840
293(2)
13.193
832
293(2)
8.318
532
293(2)
5.639
2896
293(2)
4.645
854
293(2)
5.717
740
l
(Mo K
a
) (mmꢁ1
)
F(000)
Reflections collected
Independent reflections
6070
3217
12,920
3220
5151
2736
6705
4106
12,370
6325
13,010
7713
10,814
6195
Reflections with I > 2
r
(I)
1806
0.0689, 0.1449
2414
1803
2846
0.0583, 0.1157
3458
4253
3691
b
Final indices[I > 2
r
(I) ] R1a, wR2
0.0406, 0.0811 0.1003, 0.2572
0.0466, 0.0692
0.1020, 0.0835
0.879
0.0571, 0.1036
0.1288, 0.1273
0.942
0.0823, 0.2041
0.1365, 0.2390
1.045
R1[a],wR2[b] [all data]
0.1178, 0.1751 0.0623, 0.0905 0.1359, 0.2992 0.0915, 0.1373
0.956 1.026 1.039 0.983
Goodness-of-fit (GOF) on F2,c
P
P
(||Fo| ꢁ |F||/ |F|.
P
a
b
c
R1
=
P
wR2 = [(w( (|Fo|2 ꢁ |Fc|2)2/ (w|Fo|4)]1/2
.
P
Goodness of fit = [(w( (|Fo| ꢁ |Fc|2)2]/(n ꢁ p)1/2, where n is the number of reflections, and p is the number of refined parameters.

G. Rajput et al. / Polyhedron 69 (2014) 225–233
229
Fig. 3. (a) Molecular structure and Hg–S bond distances in compounds (a) 1 and (b)
4.
Fig. 5. (a) Molecular structure of 3. (b) 1-D linear polymeric chain view of 3
projected down the axis; (c) Bond angles about mercury atom for effective square
planar coordination.
are well within the range and although longer, the Hg1–S130 dis-
tance of 2.833(8) Å is at the borderline value reported for Hg–S dis-
tances in bonding range [2a,20]. The four atoms in the equatorial
plane show an r.m.s. deviation of 0.265 Å with the metal atom
0.300(6) Å from the plane. Angles in the plane are shown in
Fig. 5c. In order to adjust the steric modularities and attain symme-
try, the S14 atom orients back and forth along the Hg1ꢀ ꢀ ꢀS13ꢀ ꢀ ꢀHg1
backbone. The 1-D polymeric chain is constructed due to the per-
force orientation of trithioxanthate and phenyl ligands on the mer-
cury atom in the crystal lattice. To the best of our knowledge 3 is
the first example of a polymeric metal trithioxanthate complex.
The conformation of the five-membered chelate ring containing
Hg1, S11, C12, S13, S14 shows that the first four atoms are approx-
imately coplanar with an r.m.s. deviation of 0.035 Å while S14 is
1.62(1) Å from the plane. Also the supramolecular structure is sus-
tained through C–Hꢀ ꢀ ꢀS (2.73 Å) non-covalent interactions and
remarkably short S13ꢀ ꢀ ꢀS14 (1 ꢁ x, y ꢁ 1/2, 1/2 ꢁ z) intermolecular
interactions at 2.536(9) Å which connect the adjacent chains.
The coordination geometry about the Hg atom in 4 is defined by
the ipso-carbon C31 of the phenyl ring and the S11 atom of the
dithiocarbamate ligand L4 with bond lengths 2.100(9) and
2.391(3) Å respectively and a C31–Hg1–S11 angle of 171.6(3)° in
addition there is a weaker Hg1–S13 bond of 2.886(3) Å Fig. 3b.
The crystal structure of 4 depicts a typical but considerably stron-
ger head to tail centrosymmetric dimer via Hg1ꢀ ꢀ ꢀS130 (0 = 2 ꢁ x,
1 ꢁ y, 2 ꢁ z) contacts (3.136(4) Å), a distance that can be compared
to that found in previously reported PhHg(II)dithiocarbamate com-
plexes, 3.117(13)–3.133(3) Å and mercury(II) dithiocarbamate
complexes 3.147(7) Å showing essentially linear geometry [2a]. It
is to be noted that in comparison to Hgꢀ ꢀ ꢀN(Py) interactions ob-
served in the reported pyridyl functionalized PhHg(II)dithiocarba-
mate complexes [11a] no such interactions occur in this compound
probably due to the steric restrictions of the methyl group on the N
of the pyrrole ring. The molecular association in the crystal struc-
Fig. 4. (a) Molecular structure and intramolecular Hgꢀ ꢀ ꢀO (2.890(8) Å) interactions
and intermolecular Hgꢀ ꢀ ꢀS (3.127(2) Å) interactions in 2. (b) Helical chain motif in 2
along the crystallographic 21 screw axis.
has been observed sporadically in methylmercury xanthate Hg(S2-
COMe)2 and carbamoylbenzenethiol mercury(II) complexes with
Hgꢀ ꢀ ꢀO distances [19b] in the range 2.65–3.06 Å. The overall supra-
molecular structure of 2 is constructed on Hg1ꢀ ꢀ ꢀS130 interactions
at (3.128(2) Å) (0 = 2 ꢁ x, 1/2 + y, 1/2 ꢁ z) presenting a helical chain
Fig. 4b around a twofold screw. The helical motif bends at S130 at
an angle of 84.6(2)° between the planes defined by S130, Hg1,
S11, C31 and C12, Hg1, S11, O14 atoms. Also the structure is stabi-
lized by non-covalent C–Hꢀ ꢀ ꢀS (2.98 Å) interactions.
In the crystal structure of 3 the Hg atom is three coordinate
with a T-shaped geometry being bonded to the ipso-carbon C31
of a phenyl ring, S11 and S13 atoms of a bidentate trithioxanthate
ligand Fig. 5a. The metal centre is also weakly coordinated to a
fourth S130 atom (0 = x, 1/2 ꢁ y, 1/2 + z) on an adjacent ligand lead-
ing to a unique linear 1-D polymeric chain and an effective coordi-
nation number of four in a distorted square planar coordination
environment; unusual for a d10 metal centre Fig. 5b,c. The Hg1–
S11 and Hg1–S13 distances of 2.358(7) and 2.644(8), respectively
ture of 4 is stabilized via C–Hꢀ ꢀ ꢀ
p interactions.
Complexes 5, 6 and 7 contain mercury(II) with various dithio
ligands. In 5 the linear, mercury(II) ion is unsymmetrically coordi-
nated by two xanthate ligands (L5). Each ligand forms a strong

230
G. Rajput et al. / Polyhedron 69 (2014) 225–233
bond and a weak bond, thus Hg1–S11 and Hg1–S41 distances are
2.381(16) and 2.370(17) Å, respectively with a S11–Hg1–S41 angle
of 172.9(7)° while Hg1–S13, Hg1–S43 are 2.953(17), 3.032(17) Å,
respectively are within the range [20] Fig. 6a. A close look into
the structure of this compound reveals a remarkable molecular
aggregation through intermolecular Hg1ꢀ ꢀ ꢀS430 (3.134(18) Å)
(0 = 1/2 ꢁ x, y ꢁ 1/2, 1.5 ꢁ z) interactions leading to generation of
a helical chain motif via a twofold screw axis Fig. 6 b,c. Thus the
effective coordination number of the metal atom is five with
distorted square pyramidal geometry which can be contrasted
with the prevalent tetrahedral geometry noticed in the majority
of analogous xanthate complexes [2a]; the only complex Hg(S2-
COMe2)2 complex [19a] containing small methyl substituents
showed the Hg atom in a T-shaped environment in a polymeric
chain. Two adjacent molecules in the helical chain network are
withe appended orthogonally at Hg1–S43–Hg1 angle of 91.89(5)°
which adjusts the steric requirements of the bulky appendages
on the OCS2 core of the ligand. The packing diagram of 5 presents
an attractive ‘butterfly shaped’ structure along the c-axis Fig. S2,
ESI. The supramolecular architecture is stabilised through substan-
tial Sꢀ ꢀ ꢀS (3.51 Å), C–Hꢀ ꢀ ꢀS (2.98 Å) and C–Hꢀ ꢀ ꢀO (2.71 Å) intermo-
lecular interactions Fig. S3, ESI.
Fig. 7. (a) Molecular structure of the dinuclear mercury complex 6 and selected
bond distances. (b) Molecular diagram and Hg–S bond lengths observed in 7.
Complex 6 is a unique centrosymmetric dinuclear mercury(II)
complex with a 3-pyridyl functionalized ligand (L6) in which each
Hg atom is unsymmetrically chelated through S11, S13 and S41,
S43 of two bidentate dithiocarbamate ligands. A fifth coordination
site on each mercury(II) ion is occupied by a N atom of a bridging-
Hg1–S41, Hg1–S13 and weaker Hg1–S43; 2.504(19), 2.422(17),
2.719(2) and 2.995(2) Å, respectively Fig. 7a. The axial position is
occupied by N260 (2 ꢁ x, 2 ꢁ y, ꢁz) at 2.375(5) Å. The angles sub-
tended at the metal from the axial N260 atom and a sulphur atom
in the equatorial plane are 109.94(14), 99.69(15), 107.22(14),
91.47(15) for S11, S13, S41 and S43 respectively. The two trans an-
gles in the equatorial plane S11–Hg1–S41 and S13–Hg1–S43 are
140.15(8) and 166.03(6)° respectively. This is a unique example
chelating dithiocarbamate ligand L6 in a l2,j
2 N,S,S fashion estab-
lishing a distorted square pyramidal geometry Fig. 7a, thus each li-
gand exhibits one short and one long bond distance. The Hg–S
bonds occupy the equatorial plane with distances for Hg1–S11,
of a dinuclear mercury(II) dithiocarbamate complex. The
s value
of 0.431 is slightly closer to a square pyramid [21] (=0) than a tri-
gonal bipyramid [21] (=1) at 0.43. The Hg1 atom lies 0.539(1) Å
above the plane of the four sulphur atoms in the equatorial plane
(r.m.s deviation = 0.262 Å) in the direction of the transannular
N260 atom. This distortion in the square pyramidal geometry
may be attributed to the longer Hg1–S43 distance (2.995(2) Å)
for the terminally chelated ligand than for the normal Hg–S bond
distances and the smaller bite angle of 65.64(6)o about the metal
atom. Intramolecular O–Hꢀ ꢀ ꢀN hydrogen bonds are formed be-
tween the N(Py) and methanolic proton of the solvent molecule
in this compound. Intermolecular C–Hꢀ ꢀ ꢀS and C–Hꢀ ꢀ ꢀ
p non-cova-
lent interactions play an important role in stabilising the supramo-
lecular structure of the molecule.
The mercury atom in 7 is bonded to two bidentate ligands L4
with dimensions 2.447(2), 2.638(2) Å for S11 and S13 and
2.523(2), 2.584(2) Å for S41 and S43 in an approximate tetrahedral
geometry Fig. 7b. The two chelate rings intersect at an angle of
82.78(2)°. The steric obstructions exerted by the orientation of
the N-methylpyrrole substituents prohibit the involvement of the
Py(N) atom in Hg–N bonding (as in 6) or the Hgꢀ ꢀ ꢀN interactions
in this complex [11a]. In the structure of 7 there are no significant
interactions between the metal and sulphur atoms from adjacent
molecules with the closest contact Hg1ꢀ ꢀ ꢀS410 (3.842 Å (0 = 1 ꢁ x,
1 ꢁ y, ꢁz). The intermolecular Sꢀ ꢀ ꢀS contacts (3.28 Å, less than
sum of van der Waals radii) between the adjacent molecules indi-
cates substantial intermolecular interactions between the aggre-
gates in the solid state. Additionally the supramolecular structure
is sustained via C–H–
interactions Fig. S3, ESI.
p, Sꢀ ꢀ ꢀS and C–Hꢀ ꢀ ꢀS weak intermolecular
In the dithiocarbamate structures, the C12–N14 bond lengths
are in the range 1.31–1.33 Å intermediate between the C–N
(1.47 Å) and C@N (1.28 Å) in accordance with the dominant
contribution of resonance form Fig. 1 of the ligand. In xanthate
Fig. 6. (a) Strong Hg1ꢀ ꢀ ꢀS13 intermolecular interactions of 3.134(18) Å in 5. (b) The
helical chain network built on Hgꢀ ꢀ ꢀS scaffold. (c) Simplified depiction of helical
chain motif in 5.

G. Rajput et al. / Polyhedron 69 (2014) 225–233
231
complexes the C12–O14 distances of 1.30–1.34 Å are somewhat
longer than the C@O distance indicating C–O character of this bond
Fig. 1. The C–S bond lengths in the range 1.655(6)–1.741(10) Å are
theoretical calculations were carried out taking some model com-
plexes as shown in Fig. 8. The iso-amyl and benzyl groups were re-
placed by the putative derivative CH3CH2 on the O-atom of the
xanthate ligand in 1 (model A) and 2 (model B) thus differing only
in the core interactions present in each model complex.
The ground state energy difference between model A and B (i.e.
EA ꢁ EB) was calculated to be ꢁ5.02 kcal/mol which can be attrib-
uted to the extra stabilization provided by the intramolecular
Hgꢀ ꢀ ꢀO bonding interactions. These results support the fact that
the stabilization due to Hgꢀ ꢀ ꢀO interactions favour the orientation
of benzyl group towards phenyl ring on Hg atom on the xanthate
ligand.
significantly shorter than the C–S single bond (ca. 1.81 Å) due to
p
electron delocalisation over the X–CS2 (X = O, N) unit. The C–S dis-
tances are also influenced by the participation of corresponding S
atoms in intra- and intermolecular Hgꢀ ꢀ ꢀS interactions leading to
supramolecular organization. The disulfide S13–S14 distance of
2.176(9) Å in the trithioxanthate complex 3 is well within the
range of disulfide linkage [12f].
A thorough inspection of crystal structures of the complexes re-
veals that apart from the non-covalent and hydrogen bonding
interactions, the interesting Hgꢀ ꢀ ꢀO and Hgꢀ ꢀ ꢀS bonding interac-
tions and Hg–N bonding are imperative in bringing out vividly
the various coordination modes about the mercury(II) ion in the
self assembly of the molecules providing variety of structural
motifs.
3.3. Electronic absorption and emission spectra
The electronic absorption spectra of the complexes 1–7 were re-
corded in CH2Cl2 solution Fig. 9 and as solid in Nujol mull Fig. S5,
ESI. The complexes 1–7 feature one high energy absorption at
240–260 nm and a low energy absorption at 275–300 nm which
3.2. Theoretical calculations
are assigned to p–
p⁄ intra ligand charge transfer (ILCT) transitions
To assess the role of intramolecular Hgꢀ ꢀ ꢀO bonding interactions
in the stabilization of the molecular structure in 2 as opposed to 1
of the dithiocarbamate and xanthate ligands [7a,22]. In Nujol mull
additional absorptions at 330–360 nm may be assigned to metal
perturbed ILCT charge transfer character [7f,22].
TDDFT calculations with various DFT functionals were per-
formed for 3. The results reveal that a low energy absorption at
297 nm (calculated value) with oscillator strength 0.59143 arises
mainly due to HOMO ? LUMO transition and may be attributed
to the electron transfer from CS3 core to OCS2 backbone in the trit-
hioxanthate ligand L30 in 3 Fig. S4, ESI. Five different functionals
(M062X [23a], LC-
xPBE [23b], CAM-B3LYP [23c], B3LYP [23d],
and B97X [23e]) were used to corroborate prominent theoretical
and experimental absorption energies. It is found that CAM-B3LYP
functional gives best results for the molecular system as in 3 and
x
Fig. 8. [A–B] Structure of model compounds employed for assessing the role of
Hgꢀ ꢀ ꢀO interactions in 2 as against 1. (Magenta-mercury, blue-hydrogen, grey-
carbon, dirty yellow-sulphur, red-oxygen). (Color online.)
Fig. 9. Electronic absorption spectra of complexes in CH2Cl2 solution.

232
G. Rajput et al. / Polyhedron 69 (2014) 225–233
Fig. 10. Solution (a) and solid (b) phase emission spectra of complexes 1–7.
the high energy absorptions in the 235–269 nm region are also
well supported Table S4, ESI.
demonstrates that the steric bulk and the type of functionality
on the N or O atom of the dithiocarbamate and xanthate ligands
and the presence or absence of a co-ligand are the key factors that
control the adoption of various coordination patterns and their
properties. The architecture of supramolecular framework is also
governed by various covalent and non covalent interactions includ-
ing those involving the metal atom. This study widens the scope of
the pyridyl functionalized ligands in conjunction with steric bulk
of the substituents on the dithio moiety for the design and synthe-
sis of molecular frameworks which may display novel structural
organization and material properties.
In comparison to other metal ions the luminescent properties of
mercury or organomercury compounds are less explored
[7f,11a,24]. The luminescent spectra of all the complexes were re-
corded in CH2Cl2 solution and solid state at 298 K. When excited at
270–300 nm in solution the 1–4 and 7 show an unstructured emis-
sion near 350 nm Fig. 10a. Complex 5 does not luminesce. The
luminescence observed in these complexes is associated with
the ligand centred transitions. The small Stokes0 shift between
the absorption and emission bands is indicative of fluorescence
emission between the singlet states. Upon excitation at 330 nm,
6 exhibits a structured emission at 370, 406 and 428 nm in solu-
tion; the significant red shifted emission in this compound may
be ascribed to enhanced delocalisation due to the naphthalene
and electron donating pyridine substituents on the NCS2 backbone
of the dithiocarbamate ligand L6 Fig. 10a, Table S6-ESI.
Acknowledgements
We gratefully acknowledge the Council of Scientific and Indus-
trial Research (CSIR), New Delhi, for SRF (GR) and Project No. 01
(2679)/12/EMR-II (NS) and the Department of Chemistry, Banaras
Hindu University, Varanasi for X-ray diffraction facility.
In the solid state upon excitation at 330–370 nm 1–4 and 7 ex-
hibit unstructured emissions at 400–500 nm however 6 retains the
structured feature of the emission bands observed in the solution
almost in the same region Fig. 10b, Table S5-ESI. Virtually equiva-
lent solution and solid state emission spectra of 6 suggests that the
dinuclear structure is retained in solution as well.
Appendix A. Supplementary data
CCDC CCDC 957325, 795905, 915319, 869392, 874505, 928155
and 869393 contain the supplementary crystallographic data for
compounds 1–7, respectively. 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: de-
posit@ccdc.cam.ac.uk. Supplementary data associated with this
article can be found, in the online version, at http://dx.doi.org/
10.1016/j.poly.2013.12.005.
4. Conclusions
Seven new PhHg(II) and mercury(II) dithiocarbamate and xan-
thate compounds have been synthesized and fully characterized.
Their X-ray structures revealed varied coordination patterns
involving the intermolecular Hgꢀ ꢀ ꢀS and less common intramolec-
ular Hgꢀ ꢀ ꢀO bonding interactions that have demonstrated unique
structural motifs in the organization of supramolecular structures
in 2 and 5 respectively. The pyridyl functionalized ligand (L6)
References
formed a l2
,j
2 N,S,S bridged dinuclear complex 6 while the analo-
[1] (a) C.S. Lai, E.R.T. Tiekink, CrystEngComm 5 (2003) 253. and references cited
therein;
gous pyridyl functionalized ligand, L4 gave a dimer 4 via Hgꢀ ꢀ ꢀS
aggregation and a mononuclear dithiocarbamate complex 7. Nota-
bly, 4 and 7 do not form polymeric chains via additional Hgꢀ ꢀ ꢀN
interactions as has been established to occur in the analogous
dithiocarbamate complexes [11a] presumably because the bulkier
(b) E.R.T. Tiekink, I. Haiduc, Prog. Inorg. Chem. 54 (2005) 127;
(c) P.J. Heard, Prog. Inorg. Chem. 53 (2005) 268;
(d) I. Haiduc, in: F. Devillanova (Ed.), Handbook of ChalcogenChemistry, Royal
Society of Chemistry, Cambridge, 2007, pp. 593–643;
(e) I. Haiduc, Secondary bonding, in: J.L. Atwood, J.W. Steed, M. Dekker (Eds.),
Encyclopaedia of Supramolecular Chemistry, CRC Press, Taylor and Francis
Group, New York, 2004, p. 1215.;
(f) I. Haiduc, in: J.A. McCleverty, T.J. Meyer, A.B.P. Lever (Eds.), Comprehensive
Coordination Chemistry II. From Biology to Nanotechnology, vol. 1, Elsevier,
Amsterdam, 2004, p. 349 (Chapter 1.15).
naphthyl and N-methyl pyrrole groups involved in the C–Hꢀ ꢀ ꢀ
p
interactions prevent the formation of close Hgꢀ ꢀ ꢀN interactions.
To the best of our knowledge the serendipitously formed 3 is the
first example of a PhHg(II) trithioxanthate complex organizing into
a 1-D polymeric chain. Compounds 2 and 5 present attractive heli-
cal chain motifs built on Hgꢀ ꢀ ꢀS bonding interactions. In the major-
ity of compounds the supramolecular structures have been
[2] (a) D. Coucouvanis, Prog. Inorg. Chem. 11 (1970) 233;
(b) D. Coucouvanis, Prog. Inorg. Chem. 26 (1979) 301;
(c) G. Hogarth, Prog. Inorg. Chem. 53 (2005) 71;
(d) J. Cookson, P.D. Beer, Dalton Trans. 15 (2007) 1459;
(e) S. Naeem, L. Delaude, A.J.P. White, J.D.E.T. Wilton-Ely, Inorg. Chem. 49
(2010) 1784.
stabilized through C–Hꢀ ꢀ ꢀ , C–Hꢀ ꢀ ꢀS, Sꢀ ꢀ ꢀS and C–Hꢀ ꢀ ꢀO secondary
p
[3] (a) M.C. Gimeno, P.G. Jones, A. Laguna, S. Sarroca, M.J. Calherda, J. Veiros,
Chem. Eur. J. 4 (1998) 2308;
interactions. Except 5, all the complexes are luminescent in both
solution and solid state. The nature of the Hgꢀ ꢀ ꢀO bonding interac-
tions in 2 have been assessed by DFT calculations. This study
(b) J.D.E.T. Wilton-Ely, D. Solanki, G. Hogarth, Eur. J. Inorg. Chem. 20 (2005)
4027;

G. Rajput et al. / Polyhedron 69 (2014) 225–233
233
(c) A. Kumar, R. Chauhan, K.C. Molloy, G. Kociok-Kohn, L. Bahadur, N. Singh,
Chem. Eur. J. 16 (2010) 4307.
(b) G. Rajput, V. Singh, S.K. Singh, L.B. Prasad, M.G.B. Drew, N. Singh, Eur. J.
Inorg. Chem. 24 (2012) 3885.
[4] (a) J.D.E.T. Wilton-Ely, D. Solanki, E.R. Knight, K.B. Holt, A.L. Thompson, G.
Hogarth, Inorg. Chem. 47 (2008) 9642;
[12] (a) J.P. Fackler Jr., J.A. Fetchin, D.C. Fries, J. Am. Chem. Soc. 94 (1972) 7323;
(b) D. Coucouvanis, S.J. Lippard, J. Am. Chem. Soc. 91 (1969) 307;
(c) A. Flamini, C. Furlani, O. Piovesana, J. Inorg. Nucl. Chem. 33 (1971) 1841;
(d) L.J. Maheu, L.H. Pignolet, Inorg. Chem. 18 (12) (1979) 3626;
(e) L.J. Maheu, L.H. Pignolet, J. Am. Chem. Soc. 102 (1980) 6346;
(f) P.J. Nieuwenhuizen, A.W. Ehlers, J.W. Hofstraat, S.R. Janse, M.W.F. Nielen,
J. Reedijk, E.-J. Baerends, Chem. Eur. J. 4 (9) (1998) 1816.
(b) R.A. Howie, G.M. de Lima, D.C. Menezes, J.L. Wardell, S.M.S.V. Wardell, D.J.
Young, E.R.T. Tiekink, CrystEngComm 10 (2008) 1626;
(c) C. Anastasiadis, G. Hogarth, J.D.E.T. Wilton-Ely, Inorg. Chim. Acta 363
(2010) 3222;
(d) G. Hogarth, E.-J.C.-R.C.R. Rainford-Brent, S.E. Kabir, I. Richards, J.D.E.T.
Wilton-Ely, Q. Zhang, Inorg. Chimica. Acta 362 (2009) 2020;
(e) S. Naeem, A.J.P. White, G. Hogarth, J.D.E.T. Wilton-Ely, Organometallics 29
(2010) 2547.
[13] A. Bril, A.W. De Jager-Veenis, J. Electrochem. Soc. 123 (1976) 396.
[14] Oxford Diffraction, CRYSALIS CCD
Oxford Diffraction Poland Sp.
, RED, version 1.711.13, copyright (1995–2003),
[5] (a) Y.S. Tan, A.L. Sudlow, K.C. Molloy, Y. Morishima, K. Fujisawa, W.J. Jackson,
W. Henderson, S.N.B.A. Halim, S.W. Ng, E.R.T. Tiekink, Cryst. Growth Des. 13
(2013) 3046;
[15] G.M. Sheldrick, SHELXS97, Program for Crystal Structure Solution, University of
Gottingen, Gottingen, 1997.
[16] G.M. Sheldrick, SHELXL97, Program for Crystal Structure Refinement, University
of Gottingen, Gottingen, 1997.
[17] M.N. Burnett, C.K. Johnson, ORTEP-III, Oak Ridge Thermal Ellipsoid Plot Program
for Crystal Structure Illustrations, Report ORNL-6895, Oak Ridge National
Laboratory, Oak Ridge, TN, USA, 1996.
[18] M.J. Frisch, G.W. Trucks, H.B. Schlegel, G.E. Scuseria, M.A. Robb, J.R. Cheeseman,
G. Scalmani, V. Barone, B. Mennucci, G.A. Petersson, H. Nakatsuji, M. Caricato,
X. Li, H.P. Hratchian, A.F. Izmaylov, J. Bloino, G. Zheng, J.L. Sonnenberg, M.
Hada, M. Ehara, K. Toyota, R. Fukuda, J. Hasegawa, M. Ishida, T. Nakajima, Y.
Honda, O. Kitao, H. Nakai, T. Vreven, J.A. Montgomery, J.E. Peralta Jr., F. Ogliaro,
M. Bearpark, J.J. Heyd, E. Brothers, K.N. Kudin, V.N. Staroverov, R. Kobayashi, J.
Normand, K. Raghavachari, A. Rendell, J. C. Burant, S.S. Iyengar, J. Tomasi, M.
Cossi, N. Rega, J.M. Millam, M. Klene, J.E. Knox, J. B. Cross, V. Bakken, C. Adamo,
J. Jaramillo, R. Gomperts, R.E. Stratmann, O. Yazyev, A.J. Austin, R. Cammi, C.
Pomelli, J. Ochterski, R.L. Martin, K. Morokuma, V. G. Zakrzewski, G.A. Voth, P.
Salvador, J.J. Dannenberg, S. Dapprich, A. D. Daniels, O. Farkas, J.B. Foresman,
J.V. Ortiz, J. Cioslowski, D.J. Fox, GAUSSIAN 09 (Revision A.2), Gaussian Inc,
Wallingford, CT, 2009.
(b) M.A. Ehsan, T.A.N. Peiris, K.G.U. Wijayantha, M.M. Olmstead, Z. Arifin, M.
Mazhar, K.M. Lo, V. McKee, Dalton Trans. 42 (2013) 10919;
(c) M.A. Malik, M. Motevalli, T. Saeed, P. O’Brien, Adv. Mater. 5 (1993) 653;
(d) N. Alam, M.S. Hill, G. K-Kohn, M. Zeller, M. Mazhar, K.C. Molloy, Chem.
Mater. 20 (2008) 6157;
(e) P. O’Brien, J.H. Park, J. Waters, Thin Solid Films 431 (2003) 502;
(f) M.S. Vickers, J. Cookson, P.D. Beer, P.T. Bishop, B. Thiebaut, J. Mater. Chem.
16 (2006) 209;
g) L. Solymar, D. Walsh, Electrical Properties of Materials, sixth ed., Oxford
University Press, New York, 1998.
[6] (a) K. Baba, T. Okamura, H. Yamamoto, T. Yamamoto, N. Ueyama, Inorg. Chem.
47 (2008) 2837;
(b) G. Henkel, B. Krebs, Chem. Rev. 104 (2004) 801;
(c) M.S. Bharara, T.H. Bui, S. Parkin, D.A. Atwood, J. Chem. Soc., Dalton Trans. 24
(2005) 3874;
(d) M.S. Bharara, S. Parkin, D.A. Atwood, Inorg. Chem. 45 (2006) 7261.
[7] (a) A. Eichhofer, G. Buth, Eur. J. Inorg. Chem. 20 (2005) 4160;
(b) M.S. Bharara, S. Parkin, D.A. Atwood, Inorg. Chem. 45 (2006) 2112;
(c) P.J. Blower, J.R. Dilworth, Coord. Chem. Rev. 76 (1987) 121;
(d) I. Casals, Polyhedron 7 (1988) 2509;
[19] (a) E.R.T. Tiekink, Acta Crystallogr. Sect., C 43 (1987) 448;
(b) M. Kato, K. Kojima, Inorg. Chem. 44 (2005) 4037;
(c) H.R. Khavasi, M.A. Fard, Cryst. Growth Des. 10 (2010) 1892.
[20] (a) A.J. Canty, G.B. Deacon, Inorg. Chim. Acta 45 (1980) L225;
(b) A. Manceau, K.L. Nagy, Dalton Trans. 11 (2008) 1421;
(c) <http://wwmm.ch.cam.ac.uk/crystaleye/bondlengths/Hg-S/Hg-N.svg>.;
(d) D. Grdenic, Angew. Chem., Int. Ed. 12 (1973) 435;
(e) I. Casals, P. G-Duarte, Inorg. Chim. Acta 184 (1991) 167;
(f) E.R.T. Tiekink, CrystEngComm 5 (2003) 101;
(g) N. Singh, A. Kumar, K.C. Molloy, M.F. Mahon, Dalton Trans. 37 (2008) 4999;
(h) X.-Y. Tang, R.-X. Yuan, Z.-G. Ren, H.-X. Li, Y. Zhang, J.-P. Lang, Inorg. Chem.
48 (2009) 2639.
(e) N.A. Bell, M. Goldstein, T. Jones, I.W. Nowell, Acta Crystallogr., Sect. B 36
(1980) 708;
(f) A. Bondi, J. Phys. Chem. 68 (3) (1964) 441;
[8] (a) S.J. Sabounchei, H. Nemattalab, S. Salehzadeh, M. Bayat, H.R. Khavasi, H.
Adams, J. Organomet. Chem. 693 (2008) 1975;
(b) L.K. Li, Y.L. Song, H.W. Hou, Z.S. Liu, Y.T. Fan, Y. Zhu, Inorg. Chim. Acta 358
(2005) 3259;
(g) A.M. Bond, R. Colton, A.F. Hollenkamp, B.F. Hoskins, K. McGregor, J. Am.
Chem. Soc. 109 (1987) 1969;
(c) M.M. Ebrahim, E.H. Stoeckli, K. Panchanatheswaran, Polyhedron 26 (2007)
3491;
(h) A.M. Bond, R. Colton, A.F. Hollenkamp, B.F. Hoskins, K. McGregor, E.R.T.
Tiekink, Inorg. Chem. 30 (1991) 192.
(d) T.J. Burchell, D.J. Eisler, R.J. Puddephatt, Inorg. Chem. 43 (2004) 5550;
(e) H.J. Nam, H.J. Lee, D.Y. Noh, Polyhedron 23 (2004) 115.
[9] (a) S.D. Cummings, R. Eisenberg, Inorg. Chem. (2004) 316;
(b) V.W.W. Yam, K.K.W. Lo, Chem. Soc. Rev. 28 (1999) 323;
(c) M.A. Mansour, W.B. Connick, R.J. Lachicotte, H.J. Gysling, R. Eisenberg,
J. Am. Chem. Soc. 120 (1998) 1329.
[21] A.W. Addison, T.N. Rao, J. Chem. Soc., Dalton Trans. (1984) 1349.
[22] A.R. Hendrickson, R.L. Martin, Aus. J. Chem. 25 (1972) 257.
[23] (a) Y. Zhao, D.G. Truhlar, Theor. Chem. Acc. 120 (2008) 215;
(b) O.A. Vydrov, J. Heyd, A.V. Krukau, G.E. Scuseria, J. Chem. Phys. 125 (2006)
234109;
(c) T. Yanai, D.P. Tew, N.C. Handy, Chem. Phys. Lett. 393 (2004) 51;
(d) A.D. Becke, Phys. Rev. B: Condens. Matter 37 (1988) 785;
(e) J.D. Chai, M. H-Gordon, J. Chem. Phys. 128 (2008) 084106.
[24] (a) W.-Y. Wong, L. Li, J.-X. Shi, Angew. Chem., Int. Ed. 42 (2003) 4064;
(b) M.R. Haneline, M. Tsunoda, F.P. Gabbai, J. Am. Chem. Soc. 124 (2002) 3737;
(c) H.P. Zhou, P. Wang, L.-X. Zheng, W.-Q. Geng, J.-H. Yin, X.-P. Gan, G.-Y. Xu, J.-
Y. Wu, Y.-P. Tian, Y.-H. Kan, X.-T. Tao, M.-H. Jiang, J. Phys. Chem. A 113 (2009)
2584.
[10] (a) J.S. Casas, E.E. Castellano, J. Ellena, I. Haiduc, Inorg. Chim. Acta 329 (2002)
71;
(b) E.R.T. Tiekink, J. Organomet. Chem. 322 (1987) 1;
(c) E.R.T. Tiekink, Acta Crystallogr. Sect. C. 50 (1994) 861;
(d) E.R.T. Tiekink, J. Organomet. Chem. 303 (1986) C53;
(e) E.J. Mensforth, M.R. Hill, S.R. Batten, Inorg. Chim. Acta 403 (2013) 9.
[11] (a) V. Singh, A. Kumar, R. Prasad, G. Rajput, M.G.B. Drew, N. Singh,
CrystEnggComm 13 (2011) 6817;