Synthesis, characterisation and study of mercury(II) chloride complexes with triphenylphosphine and heterocyclic thiones. The crystal structures of [(benzothiazole-2-thionato)-(benzothiazole-2-thione)(bis-triphenylphosphine) chloro mercury(II)] and [(μ2-dichloro){bis-pyrimidine-2-thionato)mercury(II)} {(bis-triphenylphosphine)mercury(II)} ] at 100 K

Article abstract of DOI:10.1016/S0277-5387(00)00533-7

Direct reaction of mercury(II) chloride with triphenylphosphine (PPh₃) and benzothiazole-2-thione (bzthtH) in the molar ratio of 1:1:2 results in the formation of the [Hg(PPh₃)(bzthztH)(bzthzt)CI] (1) (bzthzt = the anion of benzothiazole-2-thione) while the reaction of mercury(II) chloride with triphenylphosphine (PPh₃) and pyrimidine-2-thione (pmtH) in the molar ratio of 1:1:1 gives [Hg₂CI₂(PPh₃)₂(pmt)₂] (2) (pmt = the anion of pyrimidine-2-thione). The complexes have been characterised by their elemental analyses, melting points and their FTIR, far-IR spectroscopic data. The crystal structure of complex 1 which has been determined by single-crystal X-ray crystallography at r.t. reveals that the molecule is monomeric with tetrahedral geometry around the metal ion. A benzothiazole-2-thione molecule and a benzothiazole-2-thionato anion are coordinated, via sulfur atoms, to the mercury(II) ion [Hg-S(2A) = 2.726(2) and Hg-S(2) = 2.419(2) ?]. A triphenylphosphine molecule is also coordinated through a phosphorus atom to the metal ion [Hg-P = 2.453(2) ?] while the tetrahedral geometry around the mercury is completed by a chlorine atom [Hg-Cl = 2.633(2) ?]. The complex is covalent in the solid state. The crystal structure of complex 2 which has also been established by single-crystal X-ray crystallography at 100(1) K shows that the molecule is binuclear and consists of two different moieties with tetrahedral geometry around each mercury(II) ion. One moiety consists of a mercury(II) ion with two phosphorus atoms from phosphine ligands and two bridging chlorine atoms, while the other consists of a mercury(II) ion and two sulfur atoms of pyrimidine-2-thionato ligands. The entire complex is covalent in the solid state. The two Hg(2)-S(42) bond lengths are 2.3513(11) ? while the two Hg(1)-P(1) bond lengths are 2.4826(9) ?. The two parts of the molecule are linked to each other by two chlorine atoms with Hg(1)-Cl(1) and Hg(2)-Cl(1) bond distances of 2.5310(10) and 3.0472(10) ?, respectively.

Full text of DOI:10.1016/S0277-5387(00)00533-7

www.elsevier.nl/locate/poly
Polyhedron 19 (2000) 2231–2236
Synthesis, characterisation and study of mercury(II) chloride
complexes with triphenylphosphine and heterocyclic thiones. The
crystal structures of [(benzothiazole-2-thionato)-
(benzothiazole-2-thione)(bis-triphenylphosphine) chloro mercury(II)]
and [(m2-dichloro){(bis-pyrimidine-2-thionato)-
mercury(II)}{(bis-triphenylphosphine)mercury(II)}] at 100 K
S.K. Hadjikakou a,*, M. Kubicki b
a Department of Chemistry, Section of Inorganic and Analytical Chemistry, Uni6ersity of Ioannina, 45100 Ioannina, Greece
b Department of Chemistry, A. Mickiewicz, Uni6ersity, ul. Grunwaldzka 6, 60-78 Poznan, Poland
Received 30 June 2000; accepted 8 August 2000
Abstract
Direct reaction of mercury(II) chloride with triphenylphosphine (PPh3) and benzothiazole-2-thione (bzthtH) in the molar ratio
of 1:1:2 results in the formation of the [Hg(PPh3)(bzthztH)(bzthzt)Cl] (1) (bzthzt=the anion of benzothiazole-2-thione) while the
reaction of mercury(II) chloride with triphenylphosphine (PPh3) and pyrimidine-2-thione (pmtH) in the molar ratio of 1:1:1 gives
[Hg2Cl2(PPh3)2(pmt)2] (2) (pmt=the anion of pyrimidine-2-thione). The complexes have been characterised by their elemental
analyses, melting points and their FTIR, far-IR spectroscopic data. The crystal structure of complex 1 which has been determined
by single-crystal X-ray crystallography at r.t. reveals that the molecule is monomeric with tetrahedral geometry around the metal
ion. A benzothiazole-2-thione molecule and a benzothiazole-2-thionato anion are coordinated, via sulfur atoms, to the mercury(II)
,
ion [HgꢀS(2A)=2.726(2) and HgꢀS(2)=2.419(2) A]. A triphenylphosphine molecule is also coordinated through a phosphorus
,
atom to the metal ion [HgꢀP=2.453(2) A] while the tetrahedral geometry around the mercury is completed by a chlorine atom
,
[HgꢀCl=2.633(2) A]. The complex is covalent in the solid state. The crystal structure of complex 2 which has also been
established by single-crystal X-ray crystallography at 100(1) K shows that the molecule is binuclear and consists of two different
moieties with tetrahedral geometry around each mercury(II) ion. One moiety consists of a mercury(II) ion with two phosphorus
atoms from phosphine ligands and two bridging chlorine atoms, while the other consists of a mercury(II) ion and two sulfur atoms
of pyrimidine-2-thionato ligands. The entire complex is covalent in the solid state. The two Hg(2)ꢀS(42) bond lengths are
,
,
2.3513(11) A while the two Hg(1)ꢀP(1) bond lengths are 2.4826(9) A. The two parts of the molecule are linked to each other by
,
two chlorine atoms with Hg(1)ꢀCl(1) and Hg(2)ꢀCl(1) bond distances of 2.5310(10) and 3.0472(10) A, respectively. © 2000
Elsevier Science B.V. All rights reserved.
Keywords: Mercury(II) complexes; Triphenylphosphine; Benzothiazole-2-thione; pyrimidine-2-thione; Crystal structures
1. Introduction
taining a variety of donor atoms has been a matter of
interest over several decades [1–5]. The study of mer-
cury complexes with sulfur-containing ligands has at-
tracted considerable interest due to the relevance of this
type of molecule as structural and spectroscopic models
of biological systems [6–13]. Among the topics of inter-
est in the study of the chemistry of mercury complexes
with ligands containing thiolate or thione groups is the
potential of these ligands for use in the detoxification of
The study of the coordination and structural chem-
istry of mercury(II) halide complexes with ligands con-
* Corresponding author. Tel.: +30-651-98-374..
E-mail address: shadjika@cc.uoi.gr (S.K. Hadjikakou).
0277-5387/00/$ - see front matter © 2000 Elsevier Science B.V. All rights reserved.
PII: S0277-5387(00)00533-7

2232
S.K. Hadjikakou, M. Kubicki / Polyhedron 19 (2000) 2231–2236
mercury from living systems afforded by the binding of
mercury ions to the thiolato or thione groups of the
ligands rather than to the cystein thiolate groups of
proteins [14,15]. In the literature, there are some reports
on the interaction of heterocyclic thiones and mercury
ions [16–24]. On the other hand, the multiformity of
the structural types which have resulted for the mer-
cury(II) complexes with aryl-phosphine ligands pro-
vides an area of interest [25–29]. Surprisingly, there are
very few reports on the structural characterisation of
mixed-ligand mercury(II) complexes with heterocyclic
thiones and triaryl-phosphine ligands [30].
Here we report the structural and spectroscopic
characterisation of mercury(II) complexes derived from
the reaction of mercury(II) chloride with triphenyl-
phosphine and benzothiazole-2-thione (I, C7H5NS2) or
pyrimidine-2-thione (II, C4H4N2S) in different molar
ratios.
15.47. Calc. for C32H24ClHgN2PS4: C: 46.21; H: 2.91;
N: 3.37; S:15.42%. IR (cm−1): 1597m, 1496s, 1451s,
1433vs, 1407vs, 1332s, 1097vs, 1071vs, 1022vs, 1008vs,
985vs, 747vs, 687vs, 601vs, 519vs, 501vs, 486vs. Far-IR
(cm−1): 310m, 248s, 192s, 165s, 152s, 141m.
2.3. Synthesis of [Hg2Cl2(PPh3)2(pmt)2] (2)
A mixture of mercury(II) chloride (0.138 g, 0.5
mmol), triphenylphosphine (0.132 g, 0.5 mmol) and
pyrimidine-2-thione (0.056 g, 0.5 mmol) was suspended
in a 20 ml solution of 1:1 methanol–acetonitrile and
stirred for 3 h. The suspension was filtered off and the
clear solution was kept in darkness. Slow evaporation
of the solvent at r.t. yielded pale yellow–white crystals
suitable for single-crystal analysis by crystallography.
M.p. 220°C. Anal. Found: C: 43.29; H: 2.95; N: 4.32; S:
5.85. Calc. for C44H36Cl2Hg2N4P2S2: C: 43.36; H: 2.97;
N: 4.60; S: 5.26%. IR (cm−1): 1560s, 1537s, 1481m,
1425s, 1370vs, 1201m, 1172s, 1097s, 803s;743vs, 691vs,
519s, 504vs, 489s. Far-IR (cm−1): 248s, 227m, 177m,
172m, 165m, 151s, 134m.
2.4. X-ray data collection and reduction of the intensity
data of the complexes
X-ray diffraction data were collected on a Kuma
KM4CCD [31] diffractometer equipped with a CCD
area detector. The experiment for 1 was carried out at
r.t., while for 2 the temperature was set at 100(1) K,
using graphite–monochromated Mo Ka (u=0.71073
2. Experimental
2.1. Materials and instruments
,
A) radiation. The frames were record using Dꢀ=0.75°
All solvents used were reagent grade, mercury(II)
chloride and triphenylphosphine (Merck) as well as
benzothiazole-2-thione and pyrimidine-2-thione (Merck
or Aldrich) were used with no other purification prior
to use. Elemental analyses for C, H, N, and S were
carried out with a Carlo Erba EA model 1108. Melting
points were measured with a Stuart Scientific apparatus
and are uncorrected. IR spectra in the region of 4000–
370 cm−1 were obtained in KBr discs while far-IR
spectra in the region of 400–50 cm−1 were obtained in
polyethylene discs, with a Perkin–Elmer Spectrum GX
FTIR spectrometer.
rotation scans. A total of 782 frames in six runs were
measured for each structure. Each frame was recorded
twice in order to eliminate accidental spots. Reflection
indexing, Lorentz and polarisation correction, peak
integration and background determinations were per-
formed using the Kuma CRYSALIS RED software pack-
age [32]. The unit cell dimensions were initially
determined from the 15 appropriately chosen frames
and were then refined with all recorded images. Empir-
ical absorption corrections were applied for both data
sets; Tmin=0.40 for 1 and 0.491 for 2, Tmax=0.944 and
0.972 for 1 and 2, respectively. Both structures were
solved by direct methods using the program SHELXS-86
[33]. For each structure, full-matrix least-squares refine-
ment with all reflections was carried out with the pro-
gram SHELXL-93 [34]. Scattering factors incorporated in
2.2. Synthesis of [Hg(PPh3)(bzthztH)(bzthzt)Cl] (1)
A mixture of mercury(II) chloride (0.138 g, 0.5
mmol), triphenylphosphine (0.132 g, 0.5 mmol) and
benzothiazole-2-thione (0.167 g, 1.0 mmol) in a 20 ml
solution of 1:1 methanol–acetonitrile was stirred for 3
h. The suspension was filtered off and the clear solution
was kept in darkness. Slow evaporation of the solvent
at room temperature (r.t.) yielded orange crystals suit-
able for single-crystal analysis by crystallography. M.p.
167°C. Anal. Found: C: 46.87; H: 2.99; N: 3.76; S:
2
2 2
SHELXL-93 were used. The function ꢀ w(ꢁFoꢁ −ꢁFcꢁ )
was minimised with w−1=[h2(Fo)2+0.0504P2] (P=
[max(Fo2, 0)+2Fc2]/3)). Empirical extinction corrections
were also applied to compounds 1 and 2, according to
the formula F% =kFc[1+0.001×Fc2u3/sin 2q]1/4. The
c
final values for 1 and 2 are listed in Table 1. The
non-hydrogen atoms were refined with anisotropic ther-
mal parameters. The coordinates of the other hydrogen

S.K. Hadjikakou, M. Kubicki / Polyhedron 19 (2000) 2231–2236
2233
Table 2
atoms were calculated as 1.2 times Ueq for the appropri-
,
Selected bond lengths (A) and angles (°) for molecule 1 with e.s.d.
values in parentheses
ate carrier carbon atom. Bond lengths and angles for
both compounds are listed in Tables 2 and 3. Thermal
ellipsoid representations of the molecules together with
atomic numbering schemes are shown in Figs. 1 and 2.
Bond lengths
Hg(1)ꢀS(2)
Hg(1)ꢀP(1)
Hg(1)ꢀCl(1)
Hg(1)ꢀS(2A)
S(1)ꢀC(9)
S(1)ꢀC(2)
C(2)ꢀN(3)
C(2)ꢀS(2)
2.419(2)
2.453(2)
2.633(2)
2.726(2)
1.735(9)
1.755(8)
1.288(11) P(1)ꢀC(21)
1.726(9) P(1)ꢀC(11)
1.403(11) P(1)ꢀC(31)
1.392(12)
S(1A)ꢀC(2A)
S(1A)ꢀC(9A)
C(2A)ꢀN(3A)
C(2A)ꢀS(2A)
N(3A)ꢀC(4A)
C(4A)ꢀC(9A)
1.747(8)
1.750(9)
1.320(11)
1.690(9)
1.392(11)
1.386(12)
1.799(8)
1.802(9)
1.812(8)
2.5. Computational details
Extended Hu¨ckel calculations were performed using
the program CACAO [35]. The calculations were carried
out using crystallographic data of the molecules stud-
ied. The EHT parameters for Hg, were those estab-
lished in the literature.
N(3)ꢀC(4)
C(4)ꢀC(9)
Bond angles
S(2)ꢀHg(1)ꢀP(1)
S(2)ꢀHg(1)ꢀCl(1)
P(1)ꢀHg(1)ꢀCl(1)
S(2)ꢀHg(1) S(2A)
P(1)ꢀHg(1)ꢀS(2A)
Cl(1)ꢀHg(1)ꢀS(2A)
C(9)ꢀS(1)ꢀC(2)
N(3)ꢀC(2)ꢀS(2)
N(3)ꢀC(2)ꢀS(1)
S(2)ꢀC(2)ꢀS(1)
C(2)ꢀS(2)ꢀHg(1)
C(2)ꢀN(3)ꢀC(4)
C(5)ꢀC(4)ꢀN(3)
C(9)ꢀC(4)ꢀN(3)
C(4)ꢀC(9)ꢀS(1)
C(8)ꢀC(9)ꢀS(1)
140.79(7) N(3A)ꢀC(2A)ꢀS(2A)
101.10(8) N(3A)ꢀC(2A)ꢀS(1A)
103.30(8) S(2A)ꢀC(2A)ꢀS(1A)
108.23(8) C(2A)ꢀS(2A)ꢀHg(1)
97.66(8) C(2A)ꢀN(3A)ꢀC(4A)
99.10(7) C(5A)ꢀC(4A)ꢀC(9A)
128.2(7)
110.3(6)
121.5(5)
108.4(3)
116.5(7)
121.0(9)
127.2(9)
111.8(8)
129.5(7)
110.1(6)
106.7(4)
106.6(3)
107 7(4)
109,3(3)
113.0(3)
113.2(3)
3. Results and discussion
3.1. General aspects
89.2(4)
126.5(7)
115.1(6)
118.4(5)
97.5(3)
C(5A)ꢀC(4A)ꢀN(3A)
C(9A)ꢀC(4A)ꢀN(3A)
C(8A)ꢀC(9A)ꢀS(1A)
C(4A)ꢀC(9A)ꢀS(1A)
C(21)ꢀP(1)ꢀC(11)
C(21)ꢀP(1)ꢀC(31)
C(11)ꢀP(1)ꢀC(31)
C(21)ꢀP(1)ꢀHg(1)
C(11)ꢀP(1)ꢀHg(1)
C(31)ꢀP(1)ꢀHg(1)
Crystals of complex 1 were prepared by slow evapo-
ration of the solution remaining after the filtration of
Table 1
Crystal data and the structure refinement details for the complexes 1
and 2
111.6(7)
125.8(8)
114.3(8)
109.8(6)
129.0(8)
Compound
1
2
C
Empirical formula C32H24ClHgN2PS4
44H36Cl2Hg2N4P2S2
Formula weight
Crystal system
Space group
831.78
monoclinic
P21/c
1218.90
monoclinic
C2/c
C(2A)ꢀS(1A)ꢀC(9A) 91.3(4)
,
a (A)
10.412(2)
29.472(6)
11.039(2)
111.29(3)
3156.3(11)
4
1.75
1624
5.30
15.7674(9)
13.2146(7)
20.6533(10)
99.140(4)
4248.6(2)
2
1.91
2336
7.55
0.2×0.2×0.15
2–30
the initial product had deposited from the reaction of
HgCl2 with triphenylphosphine and benzothiazole-2-
thione in a molar ratio of 1:1:2 in methanol–acetoni-
trile solution. Smaller yields of the same product were
obtained using a 1:1:1 molar ratio of reactants. Crystals
of complex 2 were similarly obtained from the reaction
of HgCl2 with triphenylphosphine and pyrimidine-2-
thione in equimolar ratio. The formulas of the com-
plexes were firstly deduced from their elemental
analysis, m.p. and their spectroscopic data. The crystals
of the complexes are air stable when they are stored in
darkness at r.t.
,
b (A)
,
c (A)
i (o)
3
,
V (A )
Z
Dcalc (g cm−3
F(000)
)
m(mm−1
)
Crystal size (mm) 0.3×0.3×0.2
q Range (°)
hkl Range
2–30
−115h511,
−305k531,
−95l511
14771
−215h519,
−185k518,
−285l526
18062
Reflections
measured
Unique reflections 4045 (0.069)
(Rint
5511 (0.041)
254
3.2. IR spectroscopy
)
Number of
parameters
Weighting
scheme:
371
The IR spectra of complex 1 shows distinct vibra-
tional bands at 1496 and at 1332 cm−1 which have
been assigned as CꢀN bond vibrations (thioamide
bands I and II) and at 1008 and at 747 cm−1 which
were attributed to the CꢀS bond vibrations (thioamide
bands III and IV). The corresponding thioamide bands
of the free benzothiazole-2-thione ligand are given at
1490, 1320, 1010 and 860 cm−1, respectively [36,37].
The most significant change has been observed in the
thioamide band IV, supporting the sulfur donation of
the ligand upon its coordination to the metal ion. The
1
0.01
0.045
0.6
0 0.031
2
5
Extinction
parameter (k)
R (F)
0.00066(14)
0.059
0.089
1.78
0.079
wR (F2)
Goodness-of-fit
1.20
1.9/−2.6
Max/min Dz
0.9/−1.0
−3
,
(e A
)

2234
S.K. Hadjikakou, M. Kubicki / Polyhedron 19 (2000) 2231–2236
Table 3
,
Selected bond lengths (A) and angles (°) for molecule 2 with e.s.d.
values in parentheses a
Bond lengths
Hg(1)ꢀP(1)
Hg(1)ꢀCl(1)
Hg(2)ꢀS(42)
Hg(2)ꢀCl(1)
P(1)ꢀC(21)
P(1)ꢀC(11)
P(1)ꢀC(31)
2.4826(9)
2.5310(10)
2.3513(11)
3.0472(10)
1.805(4)
N(41)ꢀC(44)
N(41)ꢀC(42)
C(42)ꢀN(43)
C(42)ꢀS(42)
N(43)ꢀC(46)
C(44)ꢀC(45)
C(45)ꢀC(46)
1.333(6)
1.339(5)
1.328(5)
1.765(4)
1.340(5)
1.369(7)
1.371(6)
1.809(4)
1.814(4)
Bond ang1es
P(1)iꢀHg(1)ꢀP(1) 116.32(4)
P(1)ꢀHg(1)ꢀCl(1) 107.10(4)
P(1)ꢀHg(1)ꢀCl(1)i 113.72(4)
Cl(1)ꢀHg(1)ꢀCl(1)i 97.39(4)
S(42)iꢀHg(2)ꢀS(42) 168.11(5)
S(42)ꢀHg(2)ꢀCl(1)i 99.20(4)
S(42)ꢀHg(2)ꢀCl(1) 90.11(4)
Cl(1)iꢀHg(2)ꢀCl(1) 77.21(4)
Hg(1)ꢀCl(1)ꢀHg(2) 92.70(3)
C(21)ꢀP(1)ꢀC(11) 107.66(16)
C(21)ꢀP(1)ꢀC(31) 106.88(17)
C(11)ꢀP(1)ꢀC(31) 106.02(17)
C(21)ꢀP(1)ꢀHg(1) 114.81(12)
C(11)ꢀP(1)ꢀHg(1) 112.85(12)
C(31)ꢀP(1)ꢀHg(1) 108.11(11)
C(44)ꢀN(41)ꢀC(42) 115.4(4)
N(43)ꢀC(42)ꢀN(41)126.6(4)
N(43)ꢀC(42)ꢀS(42) 119.2(3)
N(41)ꢀC(42)ꢀS(42) 114.2(3)
C(42) S(42)ꢀHg(2) 99.82(13)
C(42)ꢀN(43)ꢀC(46) 115.6(3)
N(41)ꢀC(44)ꢀC(45) 123.3(4)
C(44)ꢀC(45)ꢀC(46) 116.2(4)
N(43)ꢀC(46)ꢀC(45) 122.9(4)
Fig. 2. Thermal ellipsoid representations of molecule 2 together with
the atomic numbering scheme.
3.3. Structure of the [Hg(PPh3)(bzthztH)(bzthzt)Cl] (1)
a Symmetry transformations used to generate equivalent atoms:
1−x, y, −z+1/2.
A view of molecule 1 is shown in Fig. 1, while selected
bondlengthsandanglesaregiveninTable2. Themolecule
is a covalent monomer in the solid state with tetrahedral
geometry around the metal ion. Two sulfur atoms, one
phosphorus atom and one chlorine atom surround the
mercury atom to build a distorted tetrahedron. Thus, one
of the two benzothiazole-2-thione molecules has been
deprotonated upon coordination. The formation of the
benzothiazole-2-thionato anion during the reaction of a
neutral thione molecule with the [Cu(PPh3)3Cl] has also
been observed and is described earlier [37]. The
bands at 687, 519, 501 and 486 cm−1 have been attributed
to the vibrations of the CꢀP bond. Further information
about the complex formation was obtained from the study
of far-IR spectra. The new bands at 137, 192 and 248
cm−1 have been assigned to the vibrations of HgꢀP, HgꢀS
and HgꢀCl bonds, respectively [22,38,39]. The IR spectra
of complex 2 shows bands at 1560 1370, 1172 and 803
cm−1 for the thioamide bands I, II, III and IV, respec-
tively, while the bands observed at 690, 508, and 489 cm−1
are characteristic for the vibrations of the PꢀC bond. The
corresponding thioamide bands of the free thione ligand
are given at 1510, 1320, 982 and 791 cm−1, respectively
[40]. The far-IR spectra of complex 2 contains new bands
at 141, 165 and 247 cm−1 which have been attributed to
theHgꢀP, HgꢀSandHgꢀClbonds, respectively[22,38,39].
,
Hg(1)ꢀS(2A) bond distance is 2.726(2) A while the
C(2A)ꢀS(2A) and C(2A)ꢀN(3A) bond distances are
,
1.690(9) and 1.320(11) A, respectively, indicating that this
ligand has been coordinated through its neutral form. The
Hg(1)ꢀS(2A) bond length is longer than those found in
,
[HgBr2(meimz2SH)]2 (HgꢀS=2.407(2) and 2.405(2) A)
Fig. 1. Thermal ellipsoid representations of molecule 1 together with the atomic numbering scheme.

S.K. Hadjikakou, M. Kubicki / Polyhedron 19 (2000) 2231–2236
2235
,
[20], [Hg(ditet)2Cl2] (HgꢀS=2.49(1) and 2.50(1) A) and
The two parts of the molecule are linked to each other
by two chlorine atoms with Hg(1)ꢀCl(1) and
Hg(2)ꢀCl(1) bond distances 2.5310(10) and 3.0472(10)
,
in [Hg(diditet)Cl2] (HgꢀS=2.42(2) A) [22], where
thione ligands have been coordinated to the metal
through their neutral form. The second Hg(1)ꢀS(2)
bond distance is 2.419(2) A, while the corresponding
C(2)ꢀS(2) and C(2)ꢀN(3) bonds are 1.726(9) and
1.288(11) A, respectively, indicating a coordination
through the anionic form of this ligand. The HgꢀS
bond length found earlier in [Hg(PPh3)2(SCN4Ph)2]
[30], where the ligand is coordinated to the mercury ion
,
A, respectively. The corresponding bond distances be-
,
tween mercury(II) and bridging Cl atoms found in the
[{HgCl2(PPh3)2}2] complex [29] are HgꢀCl(2)=2.623(8)
and HgꢀCl(2i)=2.658(8) A, respectively. The
, ,
A
,
Cl(1)ꢀHg(1)ꢀCl(1)i,
Cl(1)ꢀHg(2)ꢀCl(1)i angles are 97.39(4), 92.70(3) and
77.21(4)°, respectively. The values of the
Hg(1)ꢀCl(1)ꢀHg(2)
and
the
through its anionic form, is 2.566(3) A. The HgꢀP bond
Cl(2)ꢀHgꢀCl(2i) and HgꢀCl(2)ꢀHgi angles measured in
the [{HgCl2(PPh3)2}2] complex [29] are 85.3(3) and
94.6(3)°, respectively. The P(1)ꢀHg(1)ꢀP(1)i angle is
116.32(4)°, slightly smaller than the value of the corre-
sponding angle measured in [Hg(PPh3)2(SCN4Ph)2] [30]
(P1ꢀHgꢀP2=125.6(1)°). The S(42)ꢀHg(1)ꢀS(42)i angle
is 168.11(5)°.
,
,
length is 2.453(2) A and is similar to those found in
,
[Hg(PPh3)2(SCN4Ph)2] [30] (HgꢀP=2.500(3) A),
,
[Hg(PPh3)2(CN)2] [25] (HgꢀP=2.434(5) and 2.589(5) A,
respectively), [Hg(PPh3)2(NO3)2] [25] (HgꢀP=2.451(1)
,
A) and in [HgCl2(PPh3)2] [28] (HgꢀP=2.462(2) and
,
,
2.478(2) A). The HgꢀCl bond length is 2.633(2) A and
is longer than those measured in [HgCl2{Ph2P(S)CH2-
,
CH2(S)PPh2}] [3] (HgꢀCl=2.447(3) and 2.442(3) A,
respectively), [Hg(ditet)2Cl2] (HgꢀCl=2.51(1) and
3.5. Computational study
,
2.52(1) A [22], [{HgCl2(H2L)}2] [38] (HgꢀCl=2.532(6),
The rather unusual formation of the complex
[Hg2Cl2(PPh3)2(pmt)2] (2) prompted us to undertake a
computational study in order to verify the factors lead-
ing the formation of this type of complex towards the
formation of the [Hg(PPh3)(bzthztH)(bzthzt)Cl] (1)
complex. As it has been evidenced, the energy of the
LUMO lies 2.979 eV higher than the corresponding
HOMO’s energy in the case of complex 2 while the
energy of the LUMO lies 3.618 eV higher than the
corresponding HOMO’s energy in the case of complex
1. The differences in the HOMO–LUMO energy values
computed could explain the stability of 2. The calcu-
lated overlap population in the case of complex 1 is
0.342 and 0.657 e for the Hg(1)ꢀCl(1) and Hg(1)ꢀP(1)
bonds, respectively, and 0.330, 0.572 e for the two
Hg(1)ꢀS(2A) and Hg(1)ꢀS(2) bonds. The calculated
overlap population in the case of complex 2 is 0.639 e
for the two Hg(1)ꢀP bonds and 0.652 e for the two
Hg(2)ꢀS bonds, respectively, while the overlap popula-
tion for the Hg(1)ꢀCl(1) and Hg(2)ꢀCl(1) bonds is.0.412
and 0.108 e, respectively. The calculated net charges for
the Hg(1) and Hg(2) of complex 2 are ꢀ0.179 and 0.266,
respectively.
,
2.380(7), 2.585(6) and 2.489(7) A) and in [HgCl2-
,
(PPh3)2] [28] (HgꢀCl=2.559(2) and 2.545(3) A). The
ClꢀHgꢀS(2A) angle is 99.10(7)° indicating a NꢀH···Cl
hydrogen bond while the ClꢀHgꢀS(2) angle is
108.23(8)° and is in accordance to those measured for
the complex [Hg(ditet)2Cl2] [22] (S(1)ꢀHgꢀCl(1)=
108.6(3) and S(2)ꢀHgꢀCl(1)=104.3(3)). The PꢀHgꢀS-
(2A) angle is 97.66(8)° and is in accordance to the
corresponding angles found in [Hg(PPh3)2(SCN4Ph)2]
[30] (PꢀHgꢀS=100.37(6) and 95.7(1)°) while the
PꢀHgꢀS(2) angle is 140.79(7)°.
3.4. Structure of the [Hg2Cl2(PPh3)2(pmt)2] (2)
A view of molecule 2 is shown in Fig. 2, while
selected bond lengths and angles are given in Table 3.
The molecule is a covalent, binuclear complex which
consists of two different moieties with tetrahedral ge-
ometry around each mercury(II) ion. One moiety, con-
sists of a mercury(II) ion with two phosphorus atoms
from phosphine ligands and two bridging chlorine
atoms while the other, consists of a mercury(II) ion and
two sulfur atoms of pyrimidine-2-thionato ligands. The
whole molecule sits on a two-fold axis of symmetry
passing through the two metal atoms. The two HgꢀS
,
bond lengths are 2.3513(11) A and are in accordance
4. Supplementary material
with those found in [HgBr2(meimz2SH)]2 (HgꢀS=
,
2.407(2) and 2.405(2) A) [20], [Hg(ditet)2Cl2] (HgꢀS=
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC Nos. 140 847 for compound 1 and
140 848 for compound 2. Copies of this information
may be obtained free of charge from: The Director,
CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK
(Fax: +44-1223-336033; e-mail: deposit@ccdc.cam.
ac.uk or www: http://www.ccdc.cam.ac.uk).
,
2.49(1) and 2.50(1) A) and in [Hg(diditet)Cl2]
,
(HgꢀS=2.42(2) A) [22], while the two HgꢀP bond
lengths are 2.4826(9) A and are similar to those found
,
,
in [Hg(PPh3)2(SCN4Ph)2] [30] (HgꢀP=2.500(3) A),
,
[Hg(PPh3)2(CN)2] [25] (HgꢀP=2.434(5) and 2.589(5) A,
respectively), [Hg(PPh3)2(NO3)2] [25] (HgꢀP=2.451(1)
,
,
A) and in [{HgCl2(PPh3)2}2] [29] (HgꢀP=2.406(7) A).

2236
S.K. Hadjikakou, M. Kubicki / Polyhedron 19 (2000) 2231–2236
[20] E.S. Raper, J.R. Creighton, N.A. Bell, W. Clegg, L. Cucurull-
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