Reactions of [Rh(Tp*)(PPh3)2] (Tp=hydrotris(3,5-dimethylpyrazolyl)-borate) involving fragmentation or loss of Tp*. Structures of [Rh(Cl)2(H)(PPh3) 2(pz*)]

Article abstract of DOI:10.1016/S0277-5387(03)00475-3

The complex [Rh(Tp*)(PPh₃)₂] reacts with dichloromethane to give [Rh(Cl)(H)₂(PPh₃) ₂(pz*)] (1) and [Rh(Cl)₂(H)(PPh₃) ₂(pz*)] (2), with C₆F₅SH to give [(PPh₃)₂Rh(μ-SC₆F₅) ₂Rh(SC₆F₅)(H)(PPh₃)(pz*)] (3) and with HgCl₂ to give [{Rh(Cl)₂(PPh₃) ₂}₂Hg] (4), all under mild conditions. The crystal structures show that 2 has a slightly distorted octahedral geometry, 3 has approximately square planar Rh(I) and octahedral Rh(III) geometries, with an angle of 160.7° between the two RhS₂ planes and 4 has rhodium with a square pyramidal geometry where mercury occupies a position at the apex of the pyramid; the Rh-Hg-Rh geometry is linear and, with respect to the Rh-Hg-Rh axis, the ligands (Cl, PPh₃) on one rhodium are offset by approximately 42° relative to their counterparts on the second rhodium. In 2 an intramolecular hydrogen bond exists between the pyrazole NH and one of the chloride ligands. Structure 4 is unusual in that it contains an unsupported mercury bridge.

Full text of DOI:10.1016/S0277-5387(03)00475-3

Polyhedron 22 (2003) 3293–3298
www.elsevier.com/locate/poly
Reactions of [Rh(Tp*)(PPh3)2]
(Tp* ¼ hydrotris(3,5-dimethylpyrazolyl)-borate)
involving fragmentation or loss of Tp*. Structures
of [Rh(Cl)2(H)(PPh3)2(pz*)], [(PPh3)2Rh(l-SC6F5)2Rh
(SC6F5)(H)(PPh3)(pz*)] (pz* ¼ 3,5-dimethylpyrazole)
and [{Rh(Cl)2(PPh3)2}2Hg]
*
^
Viorel Cırcu, Manuel A. Fernandes, Laurence Carlton
Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Johannesburg, South Africa
Received 16 May 2003; accepted 24 July 2003
Abstract
The complex [Rh(Tp*)(PPh3)2] reacts with dichloromethane to give [Rh(Cl)(H)2(PPh3)2(pz*)] (1) and [Rh(Cl)2(H)(PPh3)2(pz*)]
(2), with C6F5SH to give [(PPh3)2Rh(l-SC6F5)2Rh(SC6F5)(H)(PPh3)(pz*)] (3) and with HgCl2 to give [{Rh(Cl)2(PPh3)2}2Hg] (4),
all under mild conditions. The crystal structures show that 2 has a slightly distorted octahedral geometry, 3 has approximately
square planar Rh(I) and octahedral Rh(III) geometries, with an angle of 160.7° between the two RhS2 planes and 4 has rhodium
with a square pyramidal geometry where mercury occupies a position at the apex of the pyramid; the Rh–Hg–Rh geometry is linear
and, with respect to the Rh–Hg–Rh axis, the ligands (Cl, PPh3) on one rhodium are offset by approximately 42° relative to their
counterparts on the second rhodium. In 2 an intramolecular hydrogen bond exists between the pyrazole NH and one of the chloride
ligands. Structure 4 is unusual in that it contains an unsupported mercury bridge.
Ó 2003 Elsevier Ltd. All rights reserved.
Keywords: Rhodium; 3,5-Dimethylpyrazole; Pentafluorophenylthiolate; Mercury; Crystal structures
1. Introduction
Connelly et al. [3]. Here we describe reactions of
[Rh(Tp*)(PPh3)2] with Ph3SiH/CH2Cl2, C6F5SH and
HgCl2 in which Tp* is either broken up to give 3,5-
dimethylpyrazole (pz*), which appears in the product as
a neutral ligand, or is lost altogether.
The complex [Rh(Tp*)(PPh3)2] provides a potentially
useful route to a wide variety of Rh(Tp*) derivatives via
ligand exchange and oxidative addition. Its chemistry is
expected to resemble that of the closely related com-
pound [Rh(Tp)(PPh3)2], reported by Hill et al. [1], who
describe reactions with, inter alia, ethylene, 1,5-cod, O2
and CS2. In an earlier paper we have shown that
[Rh(Tp*)(PPh3)2] combines with HX (X ¼ C2Ph, 4-
NO2C6H4CO, SnPh3) to give [Rh(Tp*)(H)(X)(PPh3)] in
moderate to good yield [2]. The structure of
[Rh(Tp*)(PPh3)2] has been reported both by us and by
2. Experimental
2.1. Materials
[Rh(Tp*)(PPh3)2] was prepared from [Rh(Cl)(PPh3)3]
and KTp* according to a procedure described in an
earlier paper [2]. Ph3SiH and C6F5SH were purchased
from Aldrich Chemicals. Dichloromethane was distilled
from P2O5. Other solvents and materials were of the
* Corresponding author. Tel.: +27-11-7176727; fax: +27-11-7176749.
E-mail address: carlton@aurum.chem.wits.ac.za (L. Carlton).
0277-5387/$ - see front matter Ó 2003 Elsevier Ltd. All rights reserved.
doi:10.1016/S0277-5387(03)00475-3

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V. Cırcu et al. / Polyhedron 22 (2003) 3293–3298
3294
highest available purity and were used without further
treatment.
product identified as [Rh(Cl)2(H)(PPh3)2(pz*)] (2) in
yields of up to 67%. 1H NMR (CD2Cl2/CH2Cl2, 27 °C):
d )15.13 (dt, J(P–H) 11.3, J(Rh–H) 12.9 Hz). 31P NMR
(CD2Cl2/CH2Cl2, 27 °C): d 29.15 (J(Rh–P) 100.9 Hz).
103Rh NMR (CD2Cl2/CH2Cl2, 27 °C): d 2091. Anal.
Calc. for C41H39Cl2N2P2Rh: C, 61.90; H, 4.94; N, 3.52.
Found: C, 62.13; H, 4.97; N, 3.25%.
2.2. Preparation of [Rh(Cl)(H)2(PPh3)2(pz*)] (1)
A mixture of [Rh(Tp*)(PPh3)2] (EtOH) (0.050 g,
0.051 mmol) and Ph3SiH (0.050 g, 0.192 mmol) in di-
chloromethane (3 ml) was heated in a sealed flask at 60–
70 °C for 90 min. The solution was cooled and treated
with a mixture of ꢀ1:1:2 hexane/ethanol/diethyl ether
(ꢀ2 ml) and allowed to stand at room temperature for 1
2.3. Preparation of [(PPh3)2Rh(l-SC6F5)2Rh(SC6F5)
(H) (PPh3)(pz*)] (3)
1
day to give colourless crystals. Yield: 0.031 g (80%). H
A solution of [Rh(Tp*)(PPh3)2](EtOH) (0.050 g,
0.051 mmol) in dichloromethane (2 ml) at room tem-
perature was treated with pentafluorophenylthiol (0.011
g, 0.055 mmol) in dichloromethane (2 ml). A color
change to dark red was observed. The mixture was al-
lowed to stand for 15 min, then concentrated to ꢀ1 ml.
Ethanol (ꢀ0.5 ml) and hexane (ꢀ0.5 ml) were added.
The product was isolated after 3 h as red–brown crys-
tals. Yield: 0.028 g (59% based on Rh; 82% based on S).
1H NMR (CD2Cl2/CH2Cl2, )25 °C): d )9.83 (dd, J(P–
H) ꢀ10.8, J(Rh–H) ꢀ10.8 Hz). 31P NMR (CD2Cl2/
NMR(CD2Cl2/CH2Cl2, 27 °C): d )16.47 (ddt, J(H–H)
10.5, J(P–H) 14.7, J(Rh–H) 14.7 Hz, 1H), )17.81 (ddt,
J(H–H) 10.5, J(P–H) 14.5, J(Rh–H) 23.0 Hz, 1H). 31P
NMR (CD2Cl2/CH2Cl2, 27 °C): d 45.54 (d, J(Rh–P)
118.3 Hz). 103Rh NMR (CD2Cl2/CH2Cl2, 27 °C): 387
ppm. Anal. Calc. for C41H40ClN2P2Rh: C, 64.70; H,
5.30; N, 3.68. Found: C, 65.08; H, 5.48; N, 3.32%. From
solutions containing the reagents in higher concentra-
tion and with more prolonged heating it was possible,
using the above procedure, to obtain yellow crystals of a
Table 1
Crystal data and structure refinement for 2, 3 and 4
[Rh(Cl)2(H)(PPh3)2
(pz*)] (2)
[(PPh3)2Rh(l-SC6F5)2Rh-(SC6F5)(H)
(PPh3)(pz*)] (tol)2 (3)
[{Rh(Cl)2(PPh3)2}2Hg]
(CH2Cl2)2 (4)
Empirical formula
Formula weight
Temperature (K)
C41H39Cl2N2P2Rh
795.49
173(2)
C91H70F15N2P3Rh2S3
1871.40
293(2)
C74H64Cl8HgP4Rh2
1767.14
173(2) K
0.71073
ꢀ
Wavelength (A)
0.71073
orthorhombic
Pnma
0.71073
triclinic
Crystal system
Space group
Unit cell dimensions
monoclinic
P2=c
ꢁ
P1
ꢀ
a (A)
16.2568(19)
23.703(3)
9.6221(11)
90
13.640(4)
17.521(5)
20.087(4)
13.731(3)
ꢀ
b (A)
ꢀ
c (A)
18.854(5)
73.571(5)
25.836(6)
90
a (°)
b (°)
c (°)
90
90
82.377(5)
74.078(6)
4149(2)
90.806(4)
90
7125(3)
3
ꢀ
Volume (A )
3707.7(8)
4
1.425
Z
2
1.498
2
1.647
3.039 mmꢁ1
3496
Density (calculated) (Mg/m3)
Absorption coefficient (mmꢁ1
F(0 0 0)
)
0.723
1632
0.613
1896
Crystal size (mm)
h range for data collection (°)
Index ranges
0.27 ꢂ 0.20 ꢂ 0.16
1.72–27.00
ꢁ20 6 h 6 20
ꢁ30 6 k 6 24
ꢁ12 6 l 6 12
21 748
0.18 ꢂ 0.08 ꢂ 0.04
1.13–25.00
ꢁ16 6 h 6 15
ꢁ18 6 k 6 20
ꢁ20 6 l 6 22
22 313
0.36 ꢂ 0.33 ꢂ 0.08
1.01–26.00
ꢁ24 6 h 6 15
ꢁ16 6 k 6 16
ꢁ31 6 l 6 31
37 749
Reflections collected
Independent reflections
Completeness to hmax (%)
Max. and Min. transmission
Data/restraints/parameters
Goodness-of-fit on F 2
4148 (Rint ¼ 0:0270)
99.9
14 479 (Rint ¼ 0:1109)
99.1
13 958 [Rint ¼ 0:0676]
99.8
0.8931 and 0.8287
4148/0/233
1.092
0.9759 and 0.8977
14 479/1/789
0.882
0.7931 and 0.4075
13 958/14/808
1.034
Final R indices [I > 2rðIÞ]
R1 ¼ 0:0434
wR2 ¼ 0:1227
R1 ¼ 0:0511
wR2 ¼ 0:1277
1.103 and )1.969
R1 ¼ 0:0739
wR2 ¼ 0:1480
R1 ¼ 0:2249
wR2 ¼ 0:1951
0.740 and )0.805
R1 ¼ 0:0606
wR2 ¼ 0:1249
R1 ¼ 0:1160
wR2 ¼ 0:1478
2.440 and )2.056
R indices (all data)
ꢁ3
ꢀ
Largest difference peaks (e A
)

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V. Cırcu et al. / Polyhedron 22 (2003) 3293–3298
3295
CH2Cl2, )25 °C): d 47.30 (dd, J(Rh–P) 177.3, J(P–P)
41.2 Hz), 38.15 (dd, J(Rh–P) 169.1, J(P–P) 41.2 Hz), d
37.58 (d, J(Rh–P) 121.6 Hz). 103Rh NMR (CD2Cl2/
CH2Cl2, )25 °C): d 2117, 239 ppm. Anal. Calc. for
C77H54F15 N2P3Rh2S3: C, 54.82; H, 3.23; N, 1.66.
Found: C, 55.12; H, 3.38; N, 1.57%.
wool, to remove some unreacted HgCl2 and traces of
metallic mercury, and treated with ethanol (2 ml). The
solution was concentrated and allowed to stand at )20
°C for 1 day to give red crystals, together with a grey
powder. The product was recrystallised from dichlo-
romethane/ethanol. Yield: 0.016 g (36% based on Rh).
31P NMR (CD2Cl2/CH2Cl2, 27 °C): d 36.04 (d, J(Rh–P)
104.6 Hz, 199Hg satellites J(119Hg–31P) 327 Hz). Anal.
Calc. for C74H64Cl8HgP4Rh2: C, 50.29; H, 3.65. Found:
C, 50.06; H, 3.85%.
2.4. Preparation of [{(PPh3)2(Cl)2Rh}2Hg](CH2Cl2)2
(4)
A mixture of [Rh(Tp*)(PPh3)2](EtOH) (0.050 g, 0.051
mmol) and HgCl2 (0.015 g, 0.055 mmol) in dichlorom-
ethane (2 ml) was stirred at room temperature for 15
min. The dark red solution was filtered through cotton
2.5. NMR spectroscopy
Spectra were recorded on a Bruker DRX 400 Spec-
trometer equipped with a 5 mm triple resonance inverse
probe with a dedicated 31P channel and extended de-
coupler range operating at 400.13 MHz (1H), 161.98
MHz (31P) and 12.65 MHz (103Rh). 103Rh spectra were
obtained by indirect detection using 31P. Chemical shifts
were referenced to TMS (1H), 85% H3PO4 (31P) and
N ¼ 3:16 MHz (103Rh).
H
H
Cl
Cl
H
Ph3SiH
CH2Cl2
Rh
Rh
pz*
pz*
Cl
PPh3
PPh3
1
2
R
S
R
S
Ph3P
Ph3P
PPh3
pz*
C6F5SH
[Rh(Tp*)(PPh3)2]
Rh
Rh
H
2.6. X-ray structure determination
S
R
3
Intensity data were collected at 20 °C (3) and )100 °C
(2; 4) on a Bruker SMART 1K CCD area detector dif-
fractometer with graphite monochromated Mo Ka ra-
diation (50 kV, 30 mA) (see Table 1). The collection
method involved x-scans of width 0.3°. Data reduction
was carried out using the program SAINT+ [4] and ab-
sorption corrections were made using the program
SADABS [5]. The crystal structures were solved by direct
Cl
Cl
Ph3P
Ph3P
Rh Hg Rh
PPh3
HgCl2
PPh3
Cl
Cl
Scheme 1. Tp* ¼ hydrotris(3,5-dimethylpyrazolyl)borate, pz* ¼ 3,5-
dimethylpyrazole, R ¼ pentafluorophenyl.
Fig. 1. ORTEP diagram of [Rh(Cl)2(H)(PPh3)2(pz*)] (2); thermal ellipsoids are shown at the 50% probability level.

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V. Cırcu et al. / Polyhedron 22 (2003) 3293–3298
3296
methods using SHELXTL [6]. Non-hydrogen atoms were
first refined isotropically followed by anistropic refine-
ment by full matrix least-squares calculation based on F 2
using SHELXTL. Hydrogen atoms were positioned geo-
metrically and allowed to ride on their respective parent
atoms. Diagrams were generated using PLATON [7].
KTpR with compounds of Rh [8] and Cu [9] and in the
reaction of [Rh(TpiPr)(dppe)] with O2 [10].
On warming with triphenylsilane in toluene at 50 °C
for 1 day [Rh(Tp*)(PPh3)2] gives [Rh(Tp*)(H)2(PPh3)]
as the major product (in solution), identified by com-
parison of its NMR data with those of an authentic
1
sample (toluene, 300 K: H, d )16.69 dd (J 31.0, 16.6
Hz); 31P d 58.58 d (J 151.3)).
3. Results and discussion
When the reaction is carried out in dichloromethane
the product [Rh(Cl)(H)2(PPh3)2(pz*)] (1) is obtained in
good yield, clearly formed by a process involving the
Three reactions of [Rh(Tp*)(PPh3)2] (Tp* ¼ hydro-
tris(3,5-dimethylpyrazolyl)-borate) in which the Tp*
ligand is either fragmented, to give a neutral pz* (1,3-
dimethylpyrazole) ligand or lost altogether are outlined
in Scheme 1. Such fragmentation is not uncommon and
has been found to occur, for example, in reactions of
1
solvent. Indeed the reaction (as monitored by H and
31P NMR) proceeds in dichloromethane in the absence
of Ph3SiH, but more slowly. The rate of the reaction
(with or without Ph3SiH) is significantly enhanced in the
presence of the free radical scavenger quinol, indicating
Table 2
Selected bond lengths (A) and angles
ꢀ
(a) [Rh(Cl)2(H)(PPh3)2(pz*)] (2)
Bond lengths
Rh–N(41
Rh–P(1)
2.096(4)
2.3249(9)
Rh–Cl(1)
Rh–Cl(2)
2.5645(14)
2.3583(17)
Rh–H(1)
1.45(2)
Bond angles
N(41)–Rh–P(1)
N(41)–Rh–Cl(1)
N(41)–Rh–Cl(2)
N(41)–Rh–H(1)
Cl(1)–Rh–Cl(2)
91.99(2)
88.08(12)
172.41(13)
89(1)
Cl(1)–Rh–H(1)
Cl(2)–Rh–H(1)
P(1)–Rh–Cl(1)
P(1)–Rh–Cl(2)
177(1)
84(1)
P(1)–Rh–P(2)
P(1)–Rh–H(1)
172.61(5)
87(1)
50(1)
93.18(2)
87.62(2)
Rh–Cl(1)–H(42)
Cl(1)–H(42)–N(42)
129(1)
99.51(6)
(b) [(PPh3)2Rh(l-SC6F5)2Rh(SC6F5)(H)(PPh3)(pz*)](tol)2 (3)
Bond lengths
Rh(1)–N(41)
Rh(1)–P(1)
Rh(1)–S(1)
Rh(1)–S(2)
2.086(8)
2.313(3)
2.353(3)
2.396(3)
Rh(1)–S(3)
Rh(1)–H(1)
Rh(2)–S(1)
2.565(3)
1.45(4)
2.432(3)
Rh(2)–S(2)
Rh(2)–P(2)
Rh(2)–P(3)
2.374(3)
2.285(3)
2.244(3)
Bond angles
N(41)–Rh(1)–P(1)
N(41)–Rh(1)–S(1)
N(41)–Rh(1)–S(2)
N(41)–Rh(1)–S(3)
N(41)–Rh(1)–H(1)
P(1)–Rh(1)–S(1)
P(1)–Rh(1)–S(2)
P(1)–Rh(1)–S(3)
91.7(3)
167.2(3)
88.7(3)
P(1)–Rh(1)–H(1)
S(1)–Rh(1)–S(2)
S(1)–Rh(1)–S(3)
S(1)–Rh(1)–H(1)
S(2)–Rh(1)–S(3)
S(2)–Rh(1)–H(1)
S(3)–Rh(1)–H(1)
Rh(1)–S(1)–Rh(2)
88(3)
Rh(1)–S(2)-Rh(2)
S(1)–Rh(2)–S(2)
S(1)–Rh(2)–P(2)
S(1)–Rh(2)–P(3)
S(2)–Rh(2)–P(2)
S(2)–Rh(2)–P(3)
P(2)–Rh(2)–P(3)
100.22(10)
77.49(9)
78.60(9)
92.37(10)
87(2)
94.57(10)
164.37(11)
171.93(11)
93.68(10)
94.38(11)
89.5(3)
92(2)
90.85(10)
94(3)
175(3)
101.04(10)
177.57(11)
86.76(10)
99.74(11)
(c) [{Rh(Cl)2(PPh3)2}2Hg](CH2Cl2)2 (4)a
Bond lengths
Rh(1)–Cl(1)
Rh(1)–Cl(2)
Rh(1)–P(1)
Rh(1)–P(2)
2.325(3)
2.341(3)
2.336(3)
2.330(3)
Rh(1)–Hg(1)
Rh(2)–Cl(3)
Rh(2)–Cl(4)
2.5494(8)
2.338(2)
2.331(3)
Rh(2)–P(3)
Rh(2)–P(4)
Rh(2)–Hg(2)
2.325(3)
2.326(3)
2.5446(9)
Bond angles
P(1)–Rh(1)–P(2)
P(1)–Rh(1)–Cl(1)
P(1)–Rh(1)–Cl(2)
P(1)–Rh(1)–Hg(1)
P(2)–Rh(1)–Cl(1)
P(2)–Rh(1)–Cl(2)
P(2)–Rh(1)–Hg(1)
Cl(1)–Rh(1)–Cl(2)
166.33(9)
89.64(9)
91.07(9)
95.99(6)
91.18(9)
86.44(9)
97.67(7)
172.78(10)
Cl(1)–Rh(1)–Hg(1)
Cl(2)–Rh(1)–Hg(1)
Rh(1)–Hg(1)–Rh(1)
P(3)–Rh(2)–P(4)
88.51(7)
98.56(7)
179.79(5)
167.03(9)
91.14(9)
86.63(9)
96.91(7)
P(4)–Rh(2)–Cl(3)
P(4)–Rh(2)–Cl(4)
P(4)–Rh(2)–Hg(2)
Cl(3)–Rh(2)–Cl(4)
Cl(3)–Rh(2)–Hg(2)
Cl(4)–Rh(2)–Hg(2)
Rh(2)–Hg(2)–Rh(2)
88.99(9)
91.72(9)
96.06(7)
173.10(9)
90.09(6)
96.66(7)
179.59(5)
P(3)–Rh(2)–Cl(3)
P(3)–Rh(2)–Cl(4)
P(3)–Rh(2)–Hg(2)
a Data are given for each of the two molecules forming the unit cell.

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V. Cırcu et al. / Polyhedron 22 (2003) 3293–3298
3297
that the mechanism is probably ionic and that the re-
action is accelerated by proton donors (hydrogen is re-
quired not only to form 1, but in the fragmentation of
Tp* in order to generate neutral pz*). Also formed in
the reaction is an unidentified compound (d(31P) d 46.62
(J 175.2 Hz) in dichloromethane, 300 K). By slight
modification of the conditions required to form 2
(higher concentrations, longer reaction times) the
product [Rh(Cl)2(H)(PPh3)2(pz*)] (2) can be obtained.
The structure of 2 is shown in Fig. 1. The two axial
phosphines are related by a mirror plane that intersects
the equatorial ligands. An intramolecular hydrogen
bond exists between the pyrazole NH(41) and Cl(1).
Bond lengths and angles are given in Table 2.
From the reaction of [Rh(Tp*)(PPh3)2] with penta-
fluorophenyl thiol a dinuclear product 3 is obtained
(Scheme 1) having Rh(I) and Rh(III) centres bridged by
two SC6F5 groups. The Rh(III) centre has an attached
pz* fragment of the original Tp*, present as a neutral
ligand, with a hydrogen most probably acquired from
the thiol. The asymmetry of the Rh(III) centre causes
the two (diastereotopic) phosphines attached to the
Rh(I) centre to exhibit different values of d(31P). The
presence of two different rhodium oxidation states in a
dinuclear thiolate bridged complex is unusual but not
unknown [11].
([Rh2(l-SC6F5)2(1,5-cod)2] [12] and [Rh2(C5Me5)2(l-
SC6F5)3]þ [13]) have been structurally characterised and
show Rh–S–Rh angles that are significantly smaller than
for 3. Complexes containing bridging SC6H5, for ex-
ample [Rh2(l-SC6H5)2(CO)2(PMe3)2] [14] also show
Rh–S–Rh angles (79.2°, 80.2°) that are up to 20° smaller
than for 3. The angle between the planes defined by
S(1)–Rh(1)–S(2) and S(1)–Rh(2)–S(2) is also larger for 3
(160.7°) than for [Rh2(l-SC6F5)2(1,5-cod)] (118.4°) and
[Rh2(l-SC6H5)2(CO)2(PMe3)2] (114.9°). It is likely that
the bulky ligands of 3, and the fact that one rhodium is
six-coordinate, prevent a closer approach of the two Rh
atoms.
Mercuric chloride reacts with [Rh(Tp*)(PPh3)2] to
give a mercury bridged dirhodium complex (4) from
which the Tp* ligand has been entirely lost (Scheme 1
and Fig. 3). To our knowledge this is the first such
complex in which the mercury bridge between the rho-
dium atoms is unsupported by additional bonds (several
examples are known of structures in which the bridge is
supported [15–20]). The unit cell contains two non-
identical molecules (one only is shown in Fig. 3; data for
both are given in Table 2) which show only minor
structural differences. The geometry at rhodium is
square pyramidal, with rhodium lying 0.1991(2) and
ꢀ
0.2102(2) A (for the two forms, respectively) above the
The structure of 3 is shown in Fig. 2; selected bond
lengths and angles are given in Table 2. The unit cell
contains both enantiomeric forms, related to each other
by an inversion centre. Two rhodium complexes con-
taining pentafluorophenyl thiolate as a bridging ligand
mean plane defined by the two phosphorus and two
chlorine atoms. When viewed along the Rh–Hg–Rh axis
the chloride and phosphine ligands on Rh(1) are offset
by approximately 42° with respect to the same ligands
on Rh(2).
Fig. 2. ORTEP diagram of [(PPh3)2Rh(l-SC6F5)2Rh(SC6F5)(H)(PPh3)(pz*)] (3); thermal ellipsoids are shown at the 20% probability level; hy-
drogens (other than H(1)) and cocrystallised toluene are omitted.

^
V. Cırcu et al. / Polyhedron 22 (2003) 3293–3298
3298
Fig. 3. ORTEP diagram of [{Rh(Cl)2(PPh3)2}2Hg] (4); thermal ellipsoids are shown at the 50% probability level; hydrogens and cocrystallised
CH2Cl2 are omitted.
[4]
S
A
I
NT+, Version 6.02, Bruker AXS Inc., Madison, WI, USA,
4. Supplementary material
1999.
[5] G.M. Sheldrick, SADABS Version 2.03, University of Gottingen,
Germany, 1996.
€
Crystallographic data have been deposited with the
Cambridge Crystallographic Data Centre for the struc-
tures of 2, 3 and 4 with CCDC numbers: 210529, 210530
and 210531, respectively. Copies of this information
may be obtained free of charge from the Director,
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK (fax
+44-1223-336-033; e-mail: deposit@ccdc.cam.ac.uk or
www: http://www.ccdc.cam.ac.uk).
[6] SHELXTL, Version 5.1, Bruker AXS Inc., Madison, WI, 1999.
[7] A.L. Spek, Acta Cryst. A 46 (1990) C34.
[8] M. Cano, J.A. Campo, J.V. Heras, E. Pinilla, C. Rivas, A. Monge,
Polyhedron 13 (1994) 2463.
[9] L.M.L. Chia, S. Radojevic, I.J. Scowen, M. McPartlin, M.A.
Halcrow, J. Chem. Soc., Dalton Trans. (2000) 133.
[10] Y. Takahashi, M. Hashimoto, S. Hikichi, M. Akita, Y. Moro-
oka, Angew. Chem., Int. Ed. Engl. 38 (1999) 3074.
[11] A. Mayanza, J.-J. Bonnet, J. Galy, P. Kalck, R. Poilblanc, J.
Chem. Res. 146 (1980) 2101.
[12] D. Cruz-Garritz, B. Rodriguez, H. Torrens, J. Leal, Transition
Met. Chem. 9 (1984) 284.
Acknowledgements
[13] J.J. Garcia, H. Torrens, H. Adams, N.A. Bailey, A. Shacklady,
P.M. Maitlis, J. Chem. Soc., Dalton Trans. (1993) 1529.
[14] J.J. Bonnet, P. Kalck, R. Poilblanc, Inorg. Chem. 16 (1977)
1514.
We thank the University of the Witwatersrand for
financial support.
[15] R.A. Jones, F.M. Real, G. Wilkinson, A.M.R. Galas, M.B
Hursthouse, J. Chem. Soc., Dalton Trans. (1981) 126.
[16] F. Faraone, S.L. Schiavo, G. Bruno, G. Bombieri, J. Chem. Soc.,
Chem. Commun. (1984) 6.
References
[1] A.F. Hill, A.J.P. White, D.J. Williams, J.D.E.T. Wilton-Ely,
Organometallics 17 (1998) 3152.
[17] A. Tiripicchio, F.J. Lahoz, L.A. Oro, M.T. Pinillos, J. Chem. Soc.,
Chem. Commun. (1984) 936.
^
[2] V. Cırcu, M.A. Fernandes, L. Carlton, Inorg. Chem. 41 (2002)
3859.
[18] J.S. Field, R.J. Haines, E. Meintjies, B. Sigwarth, P.H. Van
Rooyen, J. Organomet. Chem. 268 (1984) C43.
[19] L.J. Farrugia, J. Chem. Soc., Chem. Commun. (1987) 147.
[20] A. Bianchini, L.J. Farrugia, Organometallics 11 (1992)
540.
[3] N.G. Connelly, D.J.H. Emslie, W.E. Geiger, O.D. Hayward, E.B.
Linehan, A.G. Orpen, M.J. Quayle, P.H. Rieger, J. Chem. Soc.,
Dalton Trans. (2001) 670.