3-(Aryl)-2-sulfanylpropenoates of mercury(II) and phenylmercury(II)

Article abstract of DOI:10.1016/j.poly.2008.04.034

Compounds [HQ]₂[Hg(L)₂] and [HQ][PhHg(L)] [where HQ = diisopropylammonium cation; L = pspa, fspa, tspa, where p = 3-(phenyl), f = 3-(2-furyl), t = 3-(2-thienyl), and spa = 2-sulfanylpropenoato] have been prepared by the reaction of m

Full text of DOI:10.1016/j.poly.2008.04.034

Polyhedron 27 (2008) 2436–2446
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
3-(Aryl)-2-sulfanylpropenoates of mercury(II) and phenylmercury(II)
José S. Casas a, Alfonso Castiñeiras a, María D. Couce b, Manuel García-Vega a, Manuel Rosende a,
a
b
Agustín Sánchez a, José Sordo a, , José M. Varela , Ezequiel M. Vázquez López
*
a Departamento de Química Inorgánica, Facultade de Farmacia, Universidade de Santiago de Compostela, 15782 Santiago de Compostela, Galicia, Spain
b Departamento de Química Inorgánica, Facultade de Química, Edificio de Ciencias Experimentais, Universidade de Vigo, 36310 Vigo, Galicia, Spain
a r t i c l e i n f o
a b s t r a c t
Article history:
Compounds [HQ]2[Hg(L)2] and [HQ][PhHg(L)] [where HQ = diisopropylammonium cation; L = pspa, fspa,
tspa, where p = 3-(phenyl), f = 3-(2-furyl), t = 3-(2-thienyl), and spa = 2-sulfanylpropenoato] have been
prepared by the reaction of mercury(II) acetate or phenylmercury(II) acetate with the corresponding acid
in the presence of diisopropylamine in ethanol. The compounds have been characterized by elemental anal-
ysis, FAB mass spectrometry and IR and NMR (1H, 13C) spectroscopy. The crystal structures of the
[HQ]2[Hg(L)2] compounds show the presence of diisopropylammonium cations and [Hg(L)2]2ꢀ anions. In
each anion the Hg atom is in an HgO2S2 environment and this can be described as nido-tbp. The crystal struc-
tures of the [HQ][PhHg(L)] compounds show the presence of diisopropylammonium cations and [PhHg(L)]ꢀ
anions in which the Hg atom adopts an HgCOS distorted T-environment. The NMR data suggest that the
coordination mode of the ligand L2ꢀ determined by X-ray diffractometry in the solid remains in solution.
Ó 2008 Elsevier Ltd. All rights reserved.
Received 10 January 2008
Accepted 23 April 2008
Available online 6 June 2008
Keywords:
Sulfanylpropenoato
Mercury(II)
IR
Phenylmercury(II)
NMR
Crystal structure
1. Introduction
The breakdown of this bond once the R–Hg fragment is S-
bonded is activated by the donating ability of other donor atoms
The useful properties of mercury and its compounds has as a
counterpart in their toxic effects. This metal is widespread today
and is emitted as a vapour into the atmosphere from both natural
and anthropogenic sources. This vapour is slowly converted to
Hg(II) by oxidative process and the mercury returns to the earth
in rainwater [1]. Hg(II) has an extremely high affinity for com-
pounds that contain sulfhydryl groups and in the blood and tissues
of humans it is bound to these groups of cysteine-containing pep-
tides and proteins. Often very stable forms include linear complexes
with two sulfur ligands; however, the Hg–S bonds are labile and for
higher coordination numbers the structures are flexible, often with
distorted trigonal or tetrahedral coordination geometries [1,2].
The methylmercury(II) cation is formed in the environment in
biotic processes by microbial metabolization and in abiotic pro-
cesses by chemical reactions that do not involve living organisms.
In marine sediments or at the bottom of lakes methylmercury(II) is
concentrated in plankton and progresses up the food chain as it is
readily absorbed and accumulated by living organisms.
that are able to provide an additional interaction to the Hg–S bond.
For the organomercurial lyase enzymes that are able to degrade
methylmercury, the influence of additional S-donor atoms from
cysteine [4] or O-donor atoms from either a phenolic group [5]
or a carboxylate group [6] have been postulated.
As alternatives to the classical chelating agents dimercaptosucci-
nic acid (DMSA) and dimercaptopropanesulfonic acid (DMPS) [7],
the 3-(aryl)-2-sulfanylpropenoic acids (where aryl = phenyl, 2-fur-
yl) were tested [8,9] as chelating agents against mercury intoxica-
tion through mobilization of the metal by complex formation. As
these complexes have not been studied we selected these two li-
gands [H2L, Scheme 1], along with the 2-thienyl derivative for com-
parative purposes, and reacted them with Hg(II) in order to prepare
and structurally characterize the respective complexes.
O
1
3
2
R
CH
C
C
H2L
The methylmercury and phenylmercury(II) cations also have a
high affinity for the S-donor atoms present in proteins, peptides
and amino acids. However, the behaviour as a toxic agent is differ-
ent; methylmercury is neurotoxic, whereas the phenyl derivative
shows toxic effects as Hg(II). These facts are consistent with the
easier breakdown of the Hg–C bond in the phenyl derivative [1–3].
OH
SH
6
9
6
7
6
5
5
R =
7
8
5
4
4
7
4
O
S
* Corresponding author. Tel.: +34 981528074; fax: +34 981547102.
E-mail address: qijsordo@usc.es (J. Sordo).
H2fspa
H2pspa
H2tspa
0277-5387/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2008.04.034

J.S. Casas et al. / Polyhedron 27 (2008) 2436–2446
2437
(HQ). Recrystallization from an ethanol–dmso mixture gave crys-
tals suitable for an X-ray study.
This structural study is relevant because, although there are
previous results on S-donor ligands coordinated to Hg(II) and car-
boxylate ‘‘inorganic” complexes, to the best of our knowledge
Hg(II) complexes with an S2O2 kernel either do not contain or con-
tain only weakly coordinated carboxylates [10]. The contrasting
chelating ability of this class of ligand [11,12] should enable the
preparation and study of this kernel.
In addition, in the case of phenylmercury(II), an HgCSO kernel
with S,O-donor bidentate chelate ligands was not found in the lit-
erature [13] or in a search of the CSD database [14] and could con-
tribute to our understanding of Hg–C bond cleavage. As a result, we
also prepared and characterized the corresponding phenylmer-
cury(II) complexes with these ligands.
2.2.3. [HQ]2[Hg(fspa)2] (2)
H2fspa (0.90 g, 0.0053 mmol), Hg(OAc)2 (0.45 g, 0.0026 mmol),
diisopropylamine (0.54 g, 0.0053 mmol), ethanol (50 mL), yellow
solid, yield: 48.2%, M.p.: 172 °C. Anal. Calc. for C26H40N2O6S2Hg:
C, 42.1; H, 5.4; N, 3.8; S, 8.2. Found: C, 42.2; H, 5.7; N, 3.2; S,
8.6%. IR (cmꢀ1): a(CO2ꢀ) 1543s; s(CO2ꢀ) 1344vs; d(NH2+) 1620s.
m m
1H NMR (dmso-d6, ppm): d C(3)H 7.61 (s, 2), CH 3.27 (q, 4), CH3
1.17 (d, 24). 13C NMR (dmso-d6, ppm): d C(1) 169.9, C(2) 135.9,
C(3) 141.4, CH 45.9, CH3 18.70. 199Hg NMR (dmso-d6, ppm): d
ꢀ780.7. 199Hg NMR (CDCl3, ppm): d ꢀ853. FAB peaks at m/z
(%) = 642.2 (0.96) ([HQ][Hg(fspa)2] + 2H); 102.1 (100.00) (HQ).
Crystals suitable for an X-ray study were obtained from the mother
liquor.
The work described here involves the synthesis and character-
ization of compounds of the type [HQ]2[Hg(L)2], in which the Hg
atom has an HgO2S2 coordination kernel, and compounds of the
type [HQ][PhHg(L)], in which an HgCSO kernel was identified and
characterized by X-ray diffraction.
2.2.4. [HQ]2[Hg(tspa)2] (3)
H2tspa (0.90 g, 0.0048 mmol), Hg(OAc)2 (0.77 g, 0.0024 mmol),
diisopropylamine (0.49 g, 0.0048 mmol), ethanol (50 mL), white
solid, yield: 68.7%, M.p.: 168 °C. Anal. Calc. for C26H40N2O4S4Hg: C,
40.4; H, 5.2; N, 3.6; S, 16.6. Found: C, 39.8; H, 5.1; N, 3.3; S, 16.1%.
2. Experimental
2.1. Material and methods
IR (cmꢀ1): a(CO2ꢀ) 1548s; s(CO2ꢀ) 1335vs; d(NH2+) 1612m. 1H
m m
The 3-(aryl)-2-sulfanylpropenoic acids H2pspa, H2fspa and H2tspa
were prepared by condensation of the appropriate aldehyde with
rhodanine, subsequent hydrolysis in an alkaline medium and
acidification with HCl [15,16]. Mercury(II) acetate, phenylmer-
cury(II) acetate and diisopropylamine (Merck) were used as sup-
plied. Elemental analyses were performed with a Carlo-Erba 1108
microanalyser. Melting points were determined with a Büchi
apparatus and are uncorrected. IR spectra (KBr pellets or Nujol
mulls) were recorded on a Bruker IFS66V FT-IR spectrophotome-
ter and are reported in Section 2.2. 1H and 13C NMR spectra were
recorded in dmso-d6 or CDCl3 at room temperature on Bruker
AMX 300 and AMX 500 spectrometers operating at 300.14 or
500.14 (1H) and 75.46 or 125.76 MHz (13C), using 5 mm o.d.
tubes; chemical shifts are reported relative to TMS using the
solvent signal (d1H = 2.50 ppm; d13C = 39.50 ppm) as reference.
199Hg NMR were recorded in dmso-d6 and, in some cases, CDCl3
(concentration ranging from 10ꢀ2 to 2.6 ꢁ 10ꢀ2 M) at room tem-
perature on a Bruker AMX 500 spectrometer operating at 89.47
MHz. Chemical shifts are reported relative to pure dimethylmer-
cury(II) as secondary standard. Mass spectra were recorded on a
Kratos MS50TC spectrometer connected to a DS90 system and
operating in FAB conditions (Xe, 8 eV) using as liquid matrix
3-nitrobenzyl alcohol.
NMR (dmso-d6, ppm): d C(3)H 7.97 (s, 2), CH 3.27 (q, 4), CH3 1.16
(d, 24), NH2 8.96 (s, br, 4). 13C NMR (dmso-d6, ppm): d C(1)
+
170.2, C(2) 134.5, C(3) 124.6, CH 45.9, CH3 18.7. 199Hg NMR
(dmso-d6, ppm): d –810.2. FAB peaks at m/z (%) = 673.1 (0.82)
([HQ][Hg(tspa)2] + H); 102.1 (100) (HQ). Crystals suitable for an
X-ray study were obtained by recrystallization from a dmso/dmf
mixture.
2.2.5. Compounds of the type [HQ][PhHg(L)]
These compounds were prepared by reacting the appropriate
sulfanylpropenoic acid, diisopropylamine and PhHg(OAc) in etha-
nol in a 1:1:1 molar ratio. The solid formed after agitation of the
mixture at room temperature was filtered off and vacuum dried.
2.2.6. [HQ][PhHg(pspa)] (4)
H2pspa (0.90 g, 0.005 mmol), PhHg(OAc) (1.69 g, 0.005 mmol),
diisopropylamine (0.51 g, 0.005 mmol), ethanol (50 mL), white so-
lid, yield: 69.7%, M.p.: 183 °C. Anal. Calc. for C21H27NO2SHg: C,
45.2; H, 4.9; N, 2.5; S, 5.7. Found: C, 45.0; H, 4.8; N, 2.7; S, 5.8%.
IR (cmꢀ1): a(CO2ꢀ) 1553s; s(CO2ꢀ) 1340vs; d(NH2+) 1618m. 1H
m m
NMR (dmso-d6, ppm): d C(3)H 7.66 (s, 1), CH 3.30 (q, 4), CH3
1.19 (d, 24), NH2 8.55 (s,br, 1). 13C NMR (dmso-d6, ppm): d C(1)
+
171.5, C(2) 137.9, C(3) 131.0, CH 46.0, CH3 18.9. 199Hg NMR
(dmso-d6, ppm): d ꢀ755.4. 199Hg NMR (CDCl3, ppm): d ꢀ820.9.
FAB peaks at m/z (%) = 558.10 (1.44) ([HQ][PhHg(pspa)] + H);
457.98 (1.68) ([PhHg(pspa)] + H); 102.09 (100.00) (HQ). Crys-
tals suitable for an X-ray study were obtained from the mother
liquor.
2.2. Synthesis
2.2.1. Compounds of the type [HQ]2[Hg(L)2]
These compounds were prepared by reacting diisopropylamine,
the appropriate H2L acid and Hg(OAc)2 in ethanol in a 2:2:1 molar
ratio. The solid formed after agitation of the reaction mixture at
room temperature was filtered off and vacuum dried.
2.2.7. [HQ][PhHg(fspa)] (5)
H2fspa (0.90 g, 0.0053 mmol), PhHg(OAc) (1.79 g, 0.0053 mmol),
diisopropylamine (0.54 g, 0.0053 mmol), ethanol (50 mL), white
solid, yield: 76.6%, M.p.: 172 °C. Anal. Calc. for C19H25NO3SHg: C,
41.6; H, 4.6; N, 2.6; S, 5.8. Found: C, 41.8; H, 4.6; N, 2.4; S, 5.4%. IR
2.2.2. [HQ]2[Hg(pspa)2] (1)
H2pspa (0.90 g, 0.005 mmol), Hg(OAc)2 (0.80 g, 0.0025 mmol),
diisopropylamine (0.51 g, 0.005 mmol), ethanol (50 mL), grey solid,
yield: 73.6%, M.p.: 163 °C. Anal. Calc. for C30H44N2O4S2Hg: C, 47.3;
H, 5.8; N, 3.7; S, 8.4. Found: C, 47.3; H, 5.9; N, 3.6; S, 8.9%. IR
(cmꢀ1):
m m
a(CO2ꢀ) 1546 m; s(CO2ꢀ) 1334vs; d(NH2+) 1620m. 1H
NMR (dmso-d6, ppm): d C(3)H 7.56 (s, 1), CH 3.30, CH3 1.16 (d,
12), NH2 8.68 (s,br). 13C NMR (dmso-d6, ppm): d C(1) 170.9, C(2)
+
(cmꢀ1):
m
a(CO2ꢀ) 1547s;
m
s(CO2ꢀ) 1343vs; d(NH2+) 1618s. 1H
141.4, C(3) 137.5, CH 46.0, CH3 18.8. 199Hg NMR (dmso-d6, ppm):
d ꢀ776.1. (CDCl3, ppm): d ꢀ861.5. FAB peaks at m/z (%) = 549.07
(1.31) ([HQ][PhHg(fspa)]); 447.94 (2.50) ([PhHg(fspa)] + H); 102.09
(100.00) (HQ). Crystals suitable for an X-ray study were obtained
from the mother liquor.
+
NMR (dmso-d6, ppm): d C(3)H 7.73 (s, 2), CH3 1.18, NH2 8.85.
13C NMR (dmso, ppm): d C(1) 170.7, C(2) 135.9, C(3) 131.2, CH
46.0, CH3 18.7. 199Hg NMR (dmso-d6, ppm): d ꢀ784.7. FAB peaks
at m/z (%) = 662.2 (1.20) ([HQ][Hg(pspa)2] + 2H); 102.1 (100)

2438
J.S. Casas et al. / Polyhedron 27 (2008) 2436–2446
2.2.8. [HQ][PhHg(tspa)] (6)
absorption were carried out. The structures of 1–4 were solved
using direct methods but by the heavy atom Patterson method in
5 and 6 [21]. In the refinement the non-H atoms were treated
anisotropically [21]. The H atoms were localized from difference
Fourier maps and refined as riders (N–H 0.90, C–H 0.93–0.98 Å)
[21], except in 1 and 3 where the atomic position and isotropic
temperature factor were also refined.
The scattering factors were taken from International Tables for
Crystallography [22]. The main calculations were performed with
SHELXL-97 [21] and PLATON [20] and figures were plotted with ZORTEP
[23] and MERCURY [24].
H2tspa (0.90 g, 0.0048 mmol), PhHg(OAc) (1.63 g, 0.0048 mmol),
diisopropylamine (0.49 g, 0.0048 mmol), ethanol (50 mL), white
solid, yield: 78.7%, M.p.: 184 °C. Anal. Calc. for C19H25NO2S2Hg: C,
40.5; H, 4.4; N, 2.4; S, 11.4. Found: C, 40.3; H, 4.0; N, 2.3; S, 11.0%.
IR (cmꢀ1): a(CO2ꢀ) 1552s; s(CO2ꢀ) 1335vs; d(NH2+) 1617m. 1H
m m
NMR (dmso-d6, ppm): d C(3)H 7.97 (s, 1), CH 3.30 (q, 2), CH3 1.20
(d, 12), NH2 8.84 (s, br). 13C NMR (dmso-d6, ppm): d C(1) 171.38,
+
C(2) 134.9, C(3) 126.2, CH 45.9, CH3 18.7. 199Hg NMR (dmso-d6,
ppm): d ꢀ788.8. 199Hg NMR (CDCl3, ppm): d ꢀ839.4. FAB peaks at
m/z(%) = 565.06(1.98)([HQ][PhHg(tspa)]);463.93(3.21) ([PhHg(tspa)] +
H); 102.09 (100.00) (HQ). Crystals suitable for an X-ray study were
obtained from the mother liquor.
3. Results and discussion
2.3. X-ray studies
3.1. Compounds of the type [HQ]2[Hg(L)2]
Single crystals were mounted on glass fibres in Bruker Smart
The reaction of diisopropylamine, the corresponding H2L acid
and Hg(OAc)2 in ethanol in a 2:2:1 molar ratio gave rise to solids
with this composition. In all the cases the FAB spectra show peaks
for the protonated [HQ][Hg(L)2] species. The compounds are solu-
ble in dmso and dmf but insoluble or sparingly soluble in water,
ethanol, acetone, chloroform and acetonitrile.
1000 CCD (1–3) or Enraf-Nonius MACH3 (4–6) automatic diffrac-
tometers. Data were collected at 293 K using Mo K
a radiation
(k = 0.71073 Å). The crystal data, experimental details and refine-
ment results are summarized in Table 1.
Corrections for Lorentz effects, polarization [17] and multi-scan
(SADABS) [18] for 1–3 or semi-empirical (w scan) [19,20] for 4–6
Table 1
Crystal structure and refinement data for [HQ]2[Hg(pspa)2] (1), [HQ]2[Hg(fspa)2] (2), [HQ]2[Hg(tspa)2] (3), [HQ][PhHg(pspa)] (4), [HQ2[PhHg(fspa)] (5) and [HQ][PhHg(tspa)] (6)
Compound
[HQ]2[Hg(pspa)2] (1)
30H44N2O4S2Hg
761.38
293(2)
0.71073
monoclinic, P2(1)/n
[HQ]2[Hg(fspa)2] (2)
[HQ]2[Hg(tspa)2] (3)
[HQ][PhHg(pspa)] (4) [HQ][PhHg(fspa)] (5) [HQ][PhHg(tspa)] (6)
Empirical formula
Formula weight
Temperature (K)
Wavelength (Å)
Crystal system, space
group
C
C26H40N2O6S2Hg
741.31
293(2)
C26H40N2O4S4Hg
773.43
293(2)
0.71073
monoclinic, P2(1)/c
C21H27NO2SHg
558.09
C19H25NO3SHg
548.05
C19H25NO2S2Hg
564.11
293(2)
293(2)
293(2)
0.71073
triclinic, P1
0.71073
0.71073
0.71073
ꢀ
monoclinic, P2(1)/c
orthorhombic, Pbca
monoclinic, P2(1)/c
Unit cell dimensions
a (Å)
b (Å)
14.3539(11)
15.9545(13)
15.6774(12)
13.9291(9)
14.712(1)
18.109(1)
92.665(1)
111.939(1)
110.151(1)
3165.5(3)
4, 1.555
14.079(4)
15.321(4)
16.238(5)
8.659(2)
22.182(4)
11.092(4)
11.122(2)
17.062(4)
21.505(4)
8.300(2)
22.25(4)
11.164(2)
c (Å)
a
(°)
b (°)
111.280(2)
112.574(5)
94.80(2)
94.33(2)
94.33(2)
c
(°)
V (Å3)
3345.5(5)
4, 1.512
3234.2(16)
4, 1.588
5.049
2123.0(8)
4, 1.746
7.362
4080.6(14)
8, 1.784
7.662
2056.1(8)
4, 1.822
7.701
Z, Dcalc (Mg/m3)
Absorption coefficient 4.759
(mmꢀ1
F (000)
Crystal size (mm)
5.032
)
1528
1480
1544
1088
2128
1096
0.22 ꢁ 0.21 ꢁ 0.15
0.04 ꢁ 0.15 ꢁ 0.08
0.14 ꢁ 0.15 ꢁ 0.24
0.35 ꢁ 0.30 ꢁ 0.15
0.35 ꢁ 0.25 ꢁ 0.15
0.40 ꢁ 0.30 ꢁ 0.25
H
Range for data
1.65–28.05
1.64–28.01
1.90–27.88
2.36–27.97
2.38–27.97
3.07–27.98
collection (°)
Index ranges
ꢀ15 6 h 6 18,
ꢀ14 6 h 6 18,
ꢀ19 6 k 6 19,
ꢀ23 6 l 6 23
ꢀ18 6 h 6 18,
ꢀ20 6 k 6 20,
ꢀ21 6 l 6 21
ꢀ11 6 h 6 0,
ꢀ0 6 h 6 14,
ꢀ10 6 h 6 10,
ꢀ29 6 k 6 0,
ꢀ19 6 k 6 20,
ꢀ29 6 k 6 0,
ꢀ22 6 k 6 0,
ꢀ19 6 l 6 20
ꢀ14 6 l 6 14
ꢀ0 6 l 6 28
ꢀ14 6 l 6 0
Reflections collected/
18192/7388 [0.0664]
18142/12632 [0.0488] 24213/7415 [0.0982]
5444/5123 [0.0479]
4909/4908 [1.0764]
1575/4936 [0.0506]
unique [Rint
Completeness to theta 91.0% (h = 28.05)
]
82.4% (h = 28.01°)
semi-empirical from
equivalents
96.1% (h = 27.88)
semi-empirical from
equivalents
97.5% (h = 27.9)
semi-empirical from
equivalents
90.3% (h = 27.97)
psi scan
97.5% (h = 27.98)
psi scan
Absorption correction
multiscan
Maximum and
minimum
1.000 and 0.486
1.000 and 0.479
1.000 and 0.644
0.971 and 0.486
0.968 and 0.515
0.982 and 0.546
transmission
Refinement method
full-matrix least-
squares on F2
7388/0/364
0.704
full-matrix least-
squares on F2
12632/683
full-matrix least-
squares on F2
7415/346
full-matrix least-
squares on F2
5123/239
full-matrix least-
squares on F2
4908/230
full-matrix least-
squares on F2
4936/230
Data/parameters
Goodness-of-fit on F2
0.567
1.012
1.018
0–955
0.955
Final R indices [I > 2
(I)]
R indices (all data)
r
R1 = 0.0390,
wR2 = 0.0460
R1 = 0.1404
wR2 = 0.0570
0.868 and ꢀ0.679
R1 = 0.0467,
wR2 = 0.1038
R1 = 0.1193,
wR2 = 0.1327
1.290 and ꢀ1.098
R1 = 0.0740,
wR2 = 0.1195
R1 = 0.1661,
wR2 = 0.1431
2.096 and ꢀ1.014
R1 = 0.0450,
wR2 = 0.1018
R1 = 0.1653,
wR2 = 0.1337
1.098 and ꢀ1.359
R1 = 0.0457,
wR2 = 0.0892
R1 = 0.2123,
wR2 = 0.1317
0.866 and ꢀ1.206
R1 = 0.0466
wR2 = 0.0792
R1 = 0.1737,
wR2 = 0.1043
1.536 and ꢀ0.852
Largest difference in
peak and hole
(e Aꢀ3
)

J.S. Casas et al. / Polyhedron 27 (2008) 2436–2446
2439
3.1.1. Description of the structures of [HQ]2[Hg(pspa)2] (1),
[HQ]2[Hg(fspa)2] (2) and [HQ]2[Hg(tspa)2] (3)
and B for [Hg(fspa)2]2ꢀ (Table 3). The Hg–S bond distances range
from 2.333(2) Å for [Hg(pspa)2]2ꢀ to 2.349(3) Å for [Hg(tspa)2]2ꢀ
.
Crystals suitable for X-ray study were obtained for compounds
derived from H2pspa, H2fspa and H2tspa. As the structures have
significant similarities they are discussed together.
These values are slightly shorter than those found in Hg(II) com-
pounds with S,S0-bidentate ligands [25] to give an HgS4 environ-
ment and are in the range found for linear S–Hg–S bis-thiolato
complexes of Hg(II) [26]; the Hg–O bond distances range from
In all cases the crystals contain diisopropylammonium cations
and anions of the type [Hg(L)2]2ꢀ, where L (pspa2ꢀ, fspa2ꢀ and
tpsa2ꢀ) behaves as a bidentate chelate ligand bonded to Hg
through an O atom of the carboxylate group and the S atom of
the deprotonated SH group. The numbering scheme for the
[Hg(L)2]2ꢀ anions is shown in Fig. 1 and selected values for the
bond distances (Å) and angles (°) are given in Tables 2 and 3.
The Hg atom in all the anions is tetracoordinated in an HgO2S2
environment, with slightly different parameters in molecules A
2.499(7) Å in [Hg(tspa)2]ꢀ to 2.553(4) Å in [Hg(pspa)2]2ꢀ
.
As far as the angles around the metal are concerned, the value
for the bite angle of the ligand, which ranges from 77.56(17)° for
[Hg(fspa)2]2ꢀ to 80.04(15)° for [Hg(tspa)2]2ꢀ, is lower; the largest
value is found for the S–Hg–S angle, which ranges from
168.03(9)° in [Hg(tspa)2]2ꢀ to 171.83(8)° in the fspa derivative.
In order to investigate the influence that a possible Hg–S inter-
action between neighbouring molecules has on the S–Hg–S angle
Fig. 1. ORTEP drawing showing the structures of the [Hg(pspa)2]2ꢀ (I), the two molecules A(II) and B(III) of the [Hg(fspa)2]2ꢀ and [Hg(tspa)2]2ꢀ (IV) anions with the numbering
scheme. The ellipsoids are drawn at the 30% probability level.

2440
J.S. Casas et al. / Polyhedron 27 (2008) 2436–2446
Table 2
nificant [Hg–S(1)#1 = 3.4272(16) Å]. In the other two cases the
intermolecular Hg–S bond distances are greater than 4 Å. At this
point we must underline the variability in the sum of the van der
Waals radii for Hg and S (on using the value reported by Bondi
[27] we obtained a value of 3.3 Å for the sum of the two radii, which
was revised to 3.7 Å [13] or to 4.016 Å on using the van der Waals
radii reported by Batsanov [28]). However, the influence of this
intermolecular interaction on the bond distances and angles of
the Hg kernel does not seem to be significant.
The intermolecular interaction is also absent in [Hg(Htsal)2] [10]
and [Hg(Htsal)2] ꢂ 1,4-dioxane [29] (H2tsal = thiosalicylic acid). The
former compound, which cocrystallizes with [Hg2(tsal)2(PPh3)2],
has parameters [Hg–S: 2.3444(12), 2.3392(12) Å; Hg–O: 2.641(3),
2.682(3) Å; S–Hg–S: 170.12(4)°] close to those found in this work,
although the Hg–O bond distances are longer and the S–Hg–S angle
slightly wider. Other examples in the literature include the 2,2,6,
6-tetramethyl-3,5-heptanedione [30], the 2-dimethylamino-3-4-
dioxo-cyclobut-1-en-thiolate [26] and the N-(piperidylthiocarbon-
ylcarbonyl)benzamide [31] mercury(II) complexes and these also
have, as in the case of the thiosalicylic acid, wider S–Hg–S bond
angles than those found in this work.
Selected bond lengths (Å) and angles (°) in [HQ]2[Hg(pspa)2] (1) and [HQ]2[Hg(tspa)2]
(3)
[HQ]2[Hg(pspa)2]a (1)
[HQ]2[Hg(tspa)2] (3)
(a) Hg environment
Hg(1)–O(11)
Hg(1)–O(21)
Hg(1)–S(1)#1
Hg(1)–S(1)
2.510(4)
2.499(7)
2.518(6)
2.553(4)
3.427(2)
2.346(2)
2.333(2)
78.26(10)
110.53(11)
169.93(6)
79.45(5)
96.76(4)
106.62(11)
77.77(11)
96.95(14)
85.83(9)
156.55(11)
2.349(3)
2.346(3)
79.35(16)
109.19(15)
168.03(9)
Hg(1)–S(2)
O(11)–Hg(1)–S(1)
O(11)–Hg(1)–S(2)
S(1)–Hg(1)–S(2)
S(1)#1–Hg(1)–S(2)
S(1)#1–Hg(1)–S(1)
O(21)–Hg(1)–S(1)
O(21)–Hg(1)–S(2)
O(11)–Hg(1)–O(21)
O(11)–Hg(1)–S(1)#1
O(21)–Hg(1)–S(1)#1
106.71(16)
80.04(15)
102.9(2)
(b) Ligand
S(1)–C(12)
O(11)–C(11)
O(12)–C(11)
S(2)–C(22)
O(21)–C(21)
O(22)–C(21)
O(12)–C(11)–O(11)
O(12)–C(11)–C(12)
O(11)–C(11)–C(12)
C(13)–C(12)–S(1)
C(11)–C(12)–S(1)
O(22)–C(21)–O(21)
O(22)–C(21)–C(22)
O(21)–C(21)–C(22)
C(23)–C(22)–S(2)
C(21)–C(22)–S(2)
1.746(6)
1.258(6)
1.255(6)
1.747(10)
1.223(10)
1.259(11)
1.750(9)
1.269(10)
1.244(10)
126.1(9)
117.0(8)
116.8(9)
120.8(7)
121.5(7)
123.2(8)
118.4(9)
118.4(8)
122.0(7)
120.9(7)
For the Hg atom in the thiosalicylic acid derivative Henderson
and Nicholson [10], taking into account the large tetrahedral dis-
tortion in the kernel, proposed a nido-trigonal bipyramidal coordi-
nation geometry or even an S–Hg–S linear geometry with a weak
Hgꢂ ꢂ ꢂO interaction. The compounds described in this work have a
shorter Hg–O bond distance than that found in the thiosalicylic
acid derivative, making the nido-tbp geometry the more appropri-
ate description.
123.3(7)
118.4(6)
118.3(6)
121.1(5)
121.6(5)
The planarity of the L2ꢀ fragment is different in the three struc-
tures. In [Hg(pspa)2]2ꢀ the angle between the idealized plane of
the chelate ring and that of the C(14)–C(19) phenyl ring is 22.6°
and this value is 12.26° for the other L fragment. Equivalent angles
are 12.68° and 10.46° in molecule A and 21.68° and 5.58° in molecule
B for the fspa derivative and 10.61° and 15.52° in [HQ]2[Hg(tspa)2],
although there is a lack of planarity in the chelate ring in the latter
compound (rms [Hg(1)/S(1)/O(11)/C(11)/C(12)] = 0.0917° and rms
[Hg(1)/S(2)/O(21)/C(21)/C(22)] = 0.0970°).
a
Symmetry operations: #1 ꢀx, ꢀy, ꢀz.
Table 3
Selected bond lengths (Å) and angles (°) in [HQ]2[Hg(fspa)2] (2)
(a) Hg environment
Hg(1)–O(11A)
Hg(1)–O(21A)
Hg(2)–O(11B)
2.550(7)
2.536(6)
2.549(6)
2.540(6)
Hg(1)–S(11A)
Hg(1)–S(21A)
Hg(2)–S(11B)
Hg(2)–S(21B)
2.337(3)
2.334(3)
2.347(2)
2.336(2)
108.03(17)
78.54(18)
98.0(2)
107.19(16)
78.09(16)
98.3(2)
The diisopropylammonium cation in each of the three struc-
tures has parameters that are comparable with other previously
described examples [32,33].
Hg(2)–O(21B)
O(11A)–Hg(1)–S(11A)
O(21A)–Hg(1)–S(11A)
S(11A)–Hg(1)–S(21A)
O(11B)–Hg(2)–S(11B)
O(21B)–Hg(2)–S(11B)
S(11B)–Hg(2)–S(21B)
77.56(17)
106.95(18)
171.83(8)
79.15(16)
107.86(16)
170.90(8)
O(11A)–Hg(1)–S(21A)
O(21A)–Hg(1)–S(21A)
O(11A)–Hg(1)–O(21A)
O(11B)–Hg(2)–S(21B)
O(21B)–Hg(2)–S(21B)
O(11B)–Hg(2)–O(21B)
Table 4
Structural parameters (Å, °) describing intermolecular hydrogen bonding in the
complexes [HQ]2[Hg(L)2]a
D–H
Hꢂ ꢂ ꢂA
Dꢂ ꢂ ꢂA
D–Hꢂ ꢂ ꢂA
(b) Ligand
S(11A)–C(12A)
S(11B)–C(12B)
O(11A)–C(11A)
O(11B)–C(11B)
O(12A)–C(11A)
O(12B)–C(11B)
O(12A)–C(11A)–O(11A)
O(12B)–C(11B)–O(11B)
O(12A)–C(11A)–C(12A)
O(12B)–C(11B)–C(12B)
O(11A)–C(11A)–C(12A)
O(11B)–C(11B)–C(12B)
C(13A)–C(12A)–S(11A)
C(13B)–C(12B)–S(11B)
C(11A)–C(12A)–S(11A)
C(11B)–C(12B)–S(11B)
C(13A)–C(14A)–O(13A)
C(13B)–C(14B)–O(13B)
[HQ]2[Hg(pspa)2]
1.766(9)
1.750(9)
1.246(11)
1.282(11)
1.227(11)
1.269(10)
124.7(9)
122.8(9)
117.5(10)
119.5(9)
117.7(9)
117.6(8)
120.7(7)
120.5(7)
121.3(8)
122.9(7)
114.1(10)
113.8(9)
S(21A)–C(22A)
S(21B)–C(22B)
O(21A)–C(21A)
O(21B)–C(21B)
O(22A)–C(21A)
O(22B)–C(21B)
O(21A)–C(21A)–O(22A)
O(21B)–C(21B)–O(22B)
O(21A)–C(21A)–C(22A)
O(21B)–C(21B)–C(22B)
O(22A)–C(21A)–C(22A)
O(22B)–C(21B)–C(22B)
C(23A)–C(22A)–S(21A)
C(23B)–C(22B)–S(21B)
C(21A)–C(22A)–S(21A)
C(21B)–C(22B)–S(21B)
C(23A)–C(24A)–O(23A)
C(23B)–C(24B)–O(23B)
1.752(9)
1.758(9)
1.245(11)
1.261(10)
1.224(11)
1.231(10)
123.0(10)
123.3(8)
117.6(9)
117.7(8)
119.4(10)
118.9(9)
120.9(7)
120.6(7)
122.7(7)
122.6(7)
113.4(9)
112.4(9)
N(1)–H(1A)ꢂ ꢂ ꢂO(12)#1
N(1)–H(1B)ꢂ ꢂ ꢂO(21)
N(2)–H(2A)ꢂ ꢂ ꢂO(11)#1
N(2)–H(2B)ꢂ ꢂ ꢂO(22)
0.91(5)
1.09(5)
0.87(5)
0.97(5)
1.82(5)
1.67(5)
2.00(5)
1.72(5)
2.722(6)
2.761(6)
2.806(6)
2.692(6)
170(5)°
176(4)°
155(5)°
175(5)
[HQ]2[Hg(fspa)2]
N(11)–H(11A)ꢂ ꢂ ꢂO(12B)#2
N(11)–H(11B)ꢂ ꢂ ꢂO(11B)
N(41)–H(41A)ꢂ ꢂ ꢂO(21B)
N(41)–H(41B)ꢂ ꢂ ꢂO(12A)#4
N(21)–H(21A)ꢂ ꢂ ꢂO(22B)
N(21)–H(21B)ꢂ ꢂ ꢂO(11A)#5
N(31)–H(31A)ꢂ ꢂ ꢂO(22A)
N(31)–H(31B)ꢂ ꢂ ꢂO(21A)#3
0.90
0.90
0.90
0.90
0.90
0.90
0.90
0.90
1.82
1.89
1.84
1.94
1.95
1.88
1.84
1.89
2.708(9)
2.777(9)
2.719(9)
2.827(9)
2.831(9)
2.761(9)
2.737(9)
2.776(9)
169.6°
166.2°
163.8°
168.4°
166.2°
165.3°
172.1°
167.3°
[HQ]2[Hg(tspa)2]
N(1)–H(11A)ꢂ ꢂ ꢂO(22)#6
N(1)–H(11B)ꢂ ꢂ ꢂO(11)
N(2)–H(21A)ꢂ ꢂ ꢂO(21)#7
N(2)–H(21B)ꢂ ꢂ ꢂO(12)
0.92(9)
0.90(9)
1.01(9)
0.81(9)
1.84(9)
1.93(9)
1.79(9)
2.00(9)
2.738(10)
2.807(10)
2.769(10)
2.801(10)
164(8)°
162(8)°
163(7)°
170(9)°
a
Symmetry code: #1 x + 1/2, ꢀy + 1/2, z + 1/2; #2 ꢀx + 2, ꢀy + 1, ꢀz + 1; #3 ꢀx + 2,
ꢀy + 2, ꢀz + 1; #4 x ꢀ 1, y ꢀ 1, z; #5 x,y ꢀ 1,z; #6 ꢀx,y + 1/2, ꢀz + 1/2; #7 x, ꢀy + 1/2,
z + 1/2.
of the Hg kernel, we analysed these distances. Only in the pspa
derivative 1 were interactions found that could be considered sig-

J.S. Casas et al. / Polyhedron 27 (2008) 2436–2446
2441
The [Hg(L)]2ꢀ anions and the [HQ]+ cations are hydrogen
bonded through the NH2 group of the cation and the O atoms of
the carboxylate group. The metric parameters for these bonds are
included in Table 4. In the three structures the [HQ]+ cation bridges
two dianionic [Hg(L)]2ꢀ units but the final arrangement is different.
In [HQ]2[Hg(pspa)2], two [HQ]+ units establish a double-bridge
between two [Hg(pspa)2]2ꢀ anions to afford zig-zag chains (Fig. 2a)
parallel to the crystallographic direction {112}. These chains are
schematically represented in Fig. 2b using a rod as a symbol for the
anion and a left/right arrow as a symbol for the cation. The chains
are packed in the crystallographic c-axis, as shown in Fig. 2c, in
which the hydrogen bond and the weak Hgꢂ ꢂ ꢂS interaction are
underlined.
The same interaction in [HQ]2[Hg(fspa)2] generates rack-chains
running parallel to the crystallographic b-axis (Fig. 3) and these are
also represented using the same symbols.
In contrast to the above situation, 2D molecular association is
observed in the thiophene derivative. The crystal structure may
be described in terms of the formation of the unit shown in
Fig. 4a by bridge of four [HQ]+ units between four [Hg(tspa)2]2ꢀ
units. The cyclic unit is associated with another of these units
through interactions analogous to those described above (Fig. 4b).
The resulting sheet is parallel to the crystallographic bc-plane.
the free ligands. Furthermore, the vibrations of the CO2H group
(C@O) = 1670, 1665 and 1673 cmꢀ1 for H2pspa, H2fspa and
H2tspa are replaced by bands typical of a carboxylate group
with [
as(CO2ꢀ)] observed between 1548 and 1543 cmꢀ1 and
sym(CO2ꢀ)] between 1344 and 1335 cmꢀ1. As in other compounds
[
m
m
[m
in which the HQ cation is hydrogen bonded [12,34] to the carbox-
ꢀ
ylate group the
Dm
(=m
asCO2
–m
symCO2ꢀ) parameter has values
smaller than those found for a monodentate carboxylate group
[35], which was attributed [34] to the effect of the N–Hꢂ ꢂ ꢂO
hydrogen bond on the structural parameters of the carboxylate
group. A strong band at around 1610 cmꢀ1 in all the spectra was
assigned [36] to the d(NH2) vibration of the diisopropylammonium
cation.
The 1H NMR spectra of the complexes in all cases show the typ-
ical signals of the diisopropylammonium cation and the absence of
signals attibutable to SH and COOH groups is consistent with bide-
protonation of the ligand. These spectra show, in general, a shift of
the C(3)–H signal to higher field on complexation, which suggests
the persistence of the Hg–S bond in solution.
The persistence of the S-coordination is confirmed [37,38] by
the shift of the C(3) signal in the 13C NMR spectra. In these spectra
the C(1) signals are in positions close to those found [34,39,40] for
compounds with a monodentate coordinated carboxylate group,
thus suggesting the persistence in solution of the coordination
mode found in the solid state.
3.1.2. Spectroscopy
The IR spectra of the [HQ]2[Hg(L)2] complexes do not show
The 199Hg NMR spectra show only a signal located between
ꢀ780.7 and ꢀ810.2 ppm, indicating the presence of only one type
a m
(SH) band, which is located near 2550 cmꢀ1 in the spectra of
Fig. 2. (a) A view of the polymeric structure of [HQ]2[Hg(pspa)2] (1) and (b) a schematic view of the structure; and (c) details of the hydrogen bonding and Hgꢂ ꢂ ꢂS
intermolecular interactions.

2442
J.S. Casas et al. / Polyhedron 27 (2008) 2436–2446
Fig. 3. (a) A view of the polymeric structure of [HQ]2[Hg(fspa)2] (2) and (b) a schematic view of the structure.
Fig. 4. (a) A partial view of the polymeric structure of [HQ]2[Hg(tspa)2] (3) and (b) a schematic view of the structure.
of chemical environment for Hg(II). The position of the signal is
close to the positions found for other four-coordinated Hg(II) com-
plexes that have the HgS2N2 kernel [41]. In the case of 2 the spec-
trum was recorded in dmso/dmso-d6 (ꢀ780.7 ppm) and in CDCl3
(ꢀ853.0 ppm). The difference in the positions of the signal in these
spectra is within the accepted range [42] for the influence of the
solvent, suggesting the same chemical environment for the metal
in both solvents, thus excluding dmso coordination. The additional
coordination of these solvent molecules would increase the coordi-
nation number and should move the d (199Hg) signal to higher fre-
quencies [41].
3.2.1. Description of the structures of [HQ][PhHg(pspa)] (4),
[HQ][PhHg(fspa)] (5) and [HQ][PhHg(tspa)] (6)
Single crystals suitable for X-ray studies were obtained for
the three phenyl mercury complexes. The similarity between
the structures, indeed the structures of 4 and 6 are isotypic,
again means that these compounds will be discussed together.
The three crystals contain diisopropylammonium cations and
[HgPh(L)]ꢀ anions that interact through hydrogen bonds. The
numbering scheme for each compound is shown in Fig.
and selected bond distances (Å) and angles (°) are listed in
Table 5.
5
In each anion the ligand is S,O-bidentate chelate to give a
HgCOS kernel. It should be noted that such an example in which
O and S atoms from the same ligand has not been found previously
[13,14] for phenylmercury(II) derivatives. In this kernel the metal
adopts a significantly distorted T-environment. In this environ-
ment the Hg–C bond distance is about 2.065 Å, which is normal
for phenylmercury(II) derivatives [13] and the Hg–O and Hg–S
3.2. Compounds of the type [HQ][PhHg(L)]
Reaction of diisopropylamine, the corresponding sulfanylprope-
noic acid and PhHg(OAc) in ethanol in a 1:1:1 molar ratio gave sol-
ids with this composition. The FAB mass spectra show peaks for the
[HQ][HgPh(L)] molecular ion.

J.S. Casas et al. / Polyhedron 27 (2008) 2436–2446
2443
Fig. 5. ORTEP drawing showing the structures of [HQ][PhHg(pspa)] (4) (I), [HQ][PhHg(fspa)] (5) (II) and [HQ][PhHg(tspa)] (6) (III) with the numbering scheme. The ellipsoids
are drawn at the 30% probability level.
bond distances are close to 2.565 and 2.355 Å, respectively. The
values for the O–Hg–S, C–Hg–O and C–Hg–S angles are about
76.50°, 106.0° and 174.0°, respectively. The sum of these angles
is close to 360° in the three anions.
For other kernels values for the Hg–S bond distance between
2.357(3) and 2.405(1) Å were previously described for PhHg+ com-
pounds with thiosemicarbazones [43] and ligands containing P–S
bonds [44] and values larger than 2.370 Å have also been described

2444
J.S. Casas et al. / Polyhedron 27 (2008) 2436–2446
Table 5
Table 6
Selected bond lengths (Å) and angles (°) in [HQ][PhHg(pspa)] (4), [HQ][PhHg(fspa)]
(5) and [HQ][PhHg(tspa)] (6)
Structural parameters (Å, °) describing intermolecular hydrogen bonding in the
complexes [HQ][HgPh(L)]a
HQ][PhHg(pspa)]a
(4)
[HQ][PhHg(fspa)]
(5)
[HQ][PhHg(tspa)]b
(6)
D–H
Hꢂ ꢂ ꢂA
Dꢂ ꢂ ꢂA
D–Hꢂ ꢂ ꢂA
[HQ][PhHg(pspa)]
(a) Hg environment
Hg(1)–O(1)
Hg(1)–S(1)
Hg(1)–C(11)
Hg(1)–S(1)#1
O(1)–Hg(1)–S(1)
O(1)–Hg(1)–
S(1)#1
S(1)–Hg(1)–
S(1)#1
C(11)–Hg(1)–S(1) 173.7(3)
C(11)–Hg(1)–
S(1)#1
N(1)–H(1A)ꢂ ꢂ ꢂO(1)#1
0.90
0.90
1.95
1.84
2.833(10)
2.730(9)
167.1
169.1
2.560(6)
2.360(3)
2.060(10)
3.381(3)a
76.04(16)
93.73(17)a
2.566(7)
2.353(3)
2.060(11)
3.316(3)b
76.49(18)
97.96(19)b
2.570(6)
2.354(2)
2.075(8)
3.593(3)a
77.23(14)
93.82(14)a
N(1)–H(1B)ꢂ ꢂ ꢂO(2)
[HQ][PhHg(fspa)]
N(1)–H(1A)ꢂ ꢂ ꢂO(1)#2
0.90
0.90
1.98
1.81
2.855(11)
2.703(10)
164.9
169.7
N(1)–H(1B)ꢂ ꢂ ꢂO(2)
[HQ][PhHg(tspa)]
N(1)–H(1A)ꢂ ꢂ ꢂO(1) #1
0.90
0.90
1.93
1.84
2.809(9)
2.734(8)
165.8
169.1
89.04(9)a
88.83(9)b
91.90(9)a
N(1)–H(1B)ꢂ ꢂ ꢂO(2)
a
Symmetry code: #1 = ꢀx + 1, ꢀy + 1, ꢀz; #2 = ꢀx, ꢀy + 1, ꢀz.
174.3(3)
96.3(3)b
175.0(3)
91.4(3)a
95.6(3)a
HgCO2 environment reminiscent of the HgCOS present in this
case. The structural parameters for the latter compound [Hg–O(1):
2.585(9) Å; Hg–O(2): 2.087(7) Å; Hg–C: 2.040(11) Å; C–Hg–O(1):
112.1(4)°; C–Hg–O(2): 168.6(3)°; O(1)–Hg–O(2): 78.3(3)°] have
some similarities with these structures if the O(2) atom, trans
to C but closest to the Hg atom, is replaced by the S atom of
the sulfanylpropenoic fragment; the bite of the ligand is also
similar.
C(11)–Hg(1)–
O(1)
107.9(3)
105.2(3)
106.3(3)
(b) Ligand
S(1)–C(2)
O(1)–C(1)
O(2)–C(1)
O(2)–C(1)–O(1)
O(2)–C(1)–C(2)
O(1)–C(1)–C(2)
C(3)–C(2)–S(1)
C(1)–C(2)–S(1)
1.767(9)
1.259(11)
1.241(11)
123.6(9)
117.3(9)
119.1(8)
122.9(7)
119.6(7)
1.765(10)
1.260(13)
1.243(13)
124.8(10)
116.4(11)
118.8(10)
122.6(8)
1.759(8)
1.261(9)
1.231(9)
123.9(8)
117.5(8)
118.6(7)
121.6(6)
121.1(6)
The parameters for the diisopropylammonium cation are unre-
markable and close to those previously described.
119.3(8)
a
In the three crystals there are weak interactions, which are
weaker in the tspa derivative, and these are depicted in the struc-
tures of the pspa and fspa derivatives shown in Fig. 6. Similar inter-
actions in methylmercury xanthates of the type MeHgS(S)COR
Symmetry operation: #1 ꢀx + 1, ꢀy + 1, ꢀz + 1.
Symmetry operation: #1 ꢀx + 1, ꢀy + 1, ꢀz.
b
i
[45–49]. The values found for the Hg–O bonds can be considered
[50] typical of relatively strong bonds.
(R = Et, Pr, CH2Ph) [45] lead to supramolecular structures, but in
this case such interactions could be hindered by the hydrogen
bonds that exist between the diisopropylammonium cations and
the corresponding anions. The parameters for these bonds, which
involve the NH2 group and the carboxylate group, are listed in
Table 6.
These structures can be related with that of [HgPh(S2COEt)]
[51], in which an S-donor atom is coordinated to a PhHg+ frag-
ment to give a practically linear C–Hg–S [176.1 (4)°] environment,
and with that of [HgPh(pmbp)] (pmbp = 1-phenyl-3-methyl-4-
benzoylpyrazol-5-onato] [50] where the pmbp ligand has two
O-donor atoms, both coordinated to the Hg atom to give an
As observed in the complexes [HQ]2[Hg(L)2], the [HQ]+ units
establish two hydrogen bonds with two molecules of [HgPh(L)]ꢀ
Fig. 6. The polymeric structures of: (a) [HQ][PhHg(pspa)] (4) and (b) [HQ][PhHg(fspa)] (5).

J.S. Casas et al. / Polyhedron 27 (2008) 2436–2446
2445
to afford centrosymmetric dimers. These units are now associated
in chains running parallel to crystallographic c (compounds 4 and
6) or a (compound 5) axes (see Fig. 6) through the previously de-
scribed weak intermolecular Hg–S interaction (Table 5).
and 6. These data can be obtained free of charge via www.ccdc.ca-
m.ac.uk/conts/retrieving.html, or from the Cambridge Crystallo-
graphic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK;
fax: +44 1223 336 033; or e-mail: deposit@ccdc.cam.ac.uk. Supple-
mentary data associated with this article can be found, in the on-
line version, at doi:10.1016/j.poly.2008.04.034.
3.2.2. Spectroscopy
As for [HQ]2[Hg(L)], the IR spectra of 4, 5 and 6 do not show the
m
(SH) band and the vibrations of the CO2H group are replaced by
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D
m[
m
a(CO2ꢀ)– s(CO2ꢀ)]
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2446
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