Synthesis and characterization of half-sandwich Rh, Ir complexes containing mono-thiolate-ortho-carborane ligand

Article abstract of DOI:10.1016/j.jorganchem.2010.04.038

Two binuclear complexes [CpM(Cl)Carb^S]₂ (Cp= η⁵-C₅Me₅, M = Rh (1a), Carb^S = SC₂(H)B₁₀H₁₀, Ir (1b)) were synthesized by the reaction of LiCarb^S with the dimeric metal complexes [Cp MCl(μ-Cl)]₂ (M = Rh, Ir). Four mononuclear complexes Cp M(Cl)(L)Carb^S (L = BuⁿPPh₂, M = Rh (2a), Ir (2b); L = PPh₃, M = Rh (4a), Ir (4b)) were synthesized by reactions of 1a or 1b with L (L = BuⁿPPh₂ (2); PPh₃ (4)) in moderate yields, respectively. Complexes 3a, 3b, 5a, 5b were obtained by treatment of 2a, 2b, 4a, 4b with AgPF₆ in high yields, respectively. All of these compounds were fully characterized by IR, NMR, and elemental analysis, and the crystal structures of 1a, 1b, 2a, 2b, 4a, 4b were also confirmed by X-ray crystallography. Their structures showed 3a, 3b and 5a, 5b could be expected as good candidates for heterolytic dihydrogen activation. Preliminary experiments on the dihydrogen activation driven by these half-sandwich Rh, Ir complexes were done under mild conditions. A series of monothiolate ortho-carboranyl half-sandwich Rh, Ir complexes have been synthesized and characterized structurally. Some of these compounds could be expected as candidates for heterolytic dihydrogen activation.

Full text of DOI:10.1016/j.jorganchem.2010.04.038

Journal of Organometallic Chemistry 695 (2010) 2007e2013
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Synthesis and characterization of half-sandwich Rh, Ir complexes containing
mono-thiolate-ortho-carborane ligand
*
Xian-Kuan Huo, Ge Su, Guo-Xin Jin
Shanghai Key Laboratory of Molecular Catalysis and Innovative Material, Department of Chemistry, Fudan University, 200433 Shanghai, PR China
a r t i c l e i n f o
a b s t r a c t
Two binuclear complexes [Cp*M(Cl)CarbS]2 (Cp*
¼
h
5-C5Me5, M ¼ Rh (1a), CarbS ¼ SC2(H)B10H10, Ir (1b))
Article history:
were synthesized by the reaction of LiCarbS with the dimeric metal complexes [Cp*MCl(
m
-Cl)]2 (M ¼ Rh,
Received 13 March 2010
Received in revised form
29 April 2010
Accepted 30 April 2010
Available online 6 May 2010
Ir). Four mononuclear complexes Cp*M(Cl)(L)CarbS (L ¼ BunPPh2, M ¼ Rh (2a), Ir (2b); L ¼ PPh3, M ¼ Rh
(4a), Ir (4b)) were synthesized by reactions of 1a or 1b with L (L ¼ BunPPh2 (2); PPh3 (4)) in moderate
yields, respectively. Complexes 3a, 3b, 5a, 5b were obtained by treatment of 2a, 2b, 4a, 4b with AgPF6 in
high yields, respectively. All of these compounds were fully characterized by IR, NMR, and elemental
analysis, and the crystal structures of 1a, 1b, 2a, 2b, 4a, 4b were also confirmed by X-ray crystallography.
Their structures showed 3a, 3b and 5a, 5b could be expected as good candidates for heterolytic dihy-
drogen activation. Preliminary experiments on the dihydrogen activation driven by these half-sandwich
Rh, Ir complexes were done under mild conditions.
Keywords:
Carborane
Half-sandwich complexes
Iridium
Ó 2010 Elsevier B.V. All rights reserved.
Rhodium
Molecular structures
1. Introduction
deficient aromatic structure but also for its many promising appli-
cations such as boron neutron capture therapy (BNCT) of cancer,
During the past few years, tremendous attention and emphases
have been devoted to the activation of dihydrogen by metal
complexes [1e8], especially to the heterolytic dihydrogen activation
by sulfide- or oxo-bridged transition metal complexes [9,10], which
is not only regarded as the key reactions in the function of hydrog-
enases and catalytic desulfurization of fossil fuel, but also has some
additional advantages [1e13]. All of these features spurred the study
of transition metal thiolate chemistry, resulting in a considerate
body of important and interesting work [11e13]. However, half-
sandwich Rh, Ir complexes containing thiolate-ligands used for
activation of dihydrogen occurring at metal sulfur site remain scarce
to explore [9,10,14]. Hence, rational design and synthesis of such
complexes as models for research on dihydrogen activation is
required. At the same time, the very important factors influenced to
the formation of such metal complexes, such as reversibility,
excellent solubility in common organic solvents, unique rigidity and
gross steric bulk [9e13] were also exhibited as the great advantages
by our recent systematic ortho-carborane studies and related liter-
ature [15e18]. Additional, the chemistry of 1, 2-dicarba-closo-
dodecaborane is a fascinating research area, not only for its chemical
and thermal stability with a rigid three-dimensional electron
catalysts for olefin polymerization, molecular sensing and non-
linear optic (NLO) [19e29]. Meanwhile, CcageeH is usually func-
tionalized with different atoms such as S, S0, S, P, N, P, Si, Si0, P, P0,
forming chelating metal complexes [15e18,30e36]. However, in
view of the diversity of coordination modes and variety of coordi-
nation environment, the mono-substituted ligand is better than the
bifunctional ligands in the formation of the model complexes for the
dihydrogen activation [37e41]. In addition, half-sandwich Rh, Ir
complexes bearing the mono-substituted ortho-carborane are
scantly reported. Thus, it is of great interest to choose the mono-
thiolate o-carboranyl half-sandwich Rh, Ir complexes as models to
study the dihydrogen activation.
Herein we report a series of monothiolate ortho-carboranyl half-
sandwich complexes employing an easy but feasible way (Scheme 1).
Two of them are starting binuclear complexes [Cp*M(Cl)CarbS]2
(M ¼ Rh (1a), Ir (1b)); another eight are mononuclear complexes
Cp*M(Cl) (BunPPh2)CarbS (M ¼ Rh (2a), Ir (2b)) and [Cp*M (BunPPh2)
CarbS](PF6) (M ¼ Rh (3a), Ir (3b)); Cp*M(Cl) (PPh3)CarbS (M ¼ Rh (4a),
Ir (4b)) and [Cp*M (PPh3)CarbS](PF6) (M ¼ Rh (5a), Ir (5b)). The
structures of 1a, 1b, 2a, 2b and 4a, 4b were confirmed by X-ray
crystallography, showing 2a, 2b, 4a, 4b could have a vacant coordi-
nation site when they was treated by AgPF6. Preliminary experiments
on the dihydrogen activation driven by these half-sandwich Rh, Ir
complexes were done under mild conditions.
* Corresponding author. Tel.: þ86 21 65643776; fax: þ86 21 65641740.
E-mail address: gxjin@fudan.edu.cn (G.-X. Jin).
0022-328X/$ e see front matter Ó 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2010.04.038

2008
X.-K. Huo et al. / Journal of Organometallic Chemistry 695 (2010) 2007e2013
Scheme 1. Synthesis of 2a, 2b, 3a, 3b, 4a, 4b, 5a and 5b.
2. Results and discussion
BeH vibration at approximately 2589, 2563 cmꢀ1, 1H NMR signals
showed two sharp signals at 1.63, 3.56 ppm, which can be
ascribed to the two Cp* groups and the CcageeH respectively. 11B
NMR spectra exhibit resonances at
ꢀ2.5, ꢀ4.4, ꢀ7.1, ꢀ9.0,
d
2.1. Synthesis of ligand LiCarbS
d
The mono-substituted o-carborane derivatives have been
synthesized in aromatic solvent, but the conversion was too low for
further development of this kind of compounds, since the synthesis
of mono-substituted ortho-caborane species is synthetically more
difficult [42,43]. The preparation of them was improved by C. Vinãs
and co-authors utilizing DME as solvent and the mono-substituted
o-carborane derivatives such as 1-SH-1, 2-C2B10H11 and 1-PPh2-1,2-
C2B10H11 can be obtained in high yields [44]. In this contribution the
ligand LiCarbS was synthesized according to the literature except
the last part of acidification of the reaction products, which was
used directly for further reactions.
ꢀ11.3 ppm. Complex 1a was found to be highly soluble in most
chlorinated solvents and THF, insoluble in hexane, and partially
soluble in ether and toluene. An iridium analog 1b with the
structure formula [Cp*Ir(Cl)CarbS]2 was prepared by the similar
synthetically method. And a detailed analysis of the spectroscopic
data (IR, 1H NMR and 11B NMR) shows the structure is similar to 1a,
which was also confirmed by X-ray crystallography.
The crystallographic data for complex 1a and 1b are summa-
rized in Table 1; ORTEP drawings of complexes 1a and 1b and
selected bonds and angles are shown in Figs. 1 and 2, respectively.
The solid state molecular structure reveals there is an almost planar
four-membered ring formed by two m-M (Rh, Ir) atoms and two m-S
2.2. Synthesis and characterization of starting binuclear complexes
atoms with the distance 3.734, 3.742 Å between M(1) and M(2) and
the dihedral angle between the planes [M(1), S(1), S(1A)] and [M
(2), S(1),S(1A)] at the S/S vector of which is 13.09ꢁ, 12.56ꢁ,
respectively. The geometry at the Rh(III) or Ir(III) center bears
a three-legged piano-stool shape with M atom coordinated by the
h5-Cp*, two CarbS ligands, and one chloride atom, which can be
consequently described as pseudo-octahedron assuming h5-Cp*
group functions as a three-coordination ligand. An interesting
feature of this solid state structure is two Cp* rings are in cisoid
arrangements on one side of the M2S2 plane while the two CarbS
ligands and two chloride atoms in cisoid arrangements are on the
other side. The distances Rh(1)eS(1) (2.4212(15) Å, Rh(2)eS(1)
[Cp*M(Cl)CarbS]2 (M ¼ Rh (1a), Ir (1b))
The starting binuclear complexes were synthesized from the
reactions LiCarbS with 0.5 equiv of the dimeric metal complexes
[Cp*MCl2]2 (M ¼ Rh, Ir) in THF in moderate yields, as shown in
Scheme 2. The complexes were obtained from recrystallization in
form of air- and moist-stable, red, transparent blocks when the low
temperature was employed. The formation of a new complex [Cp*M
(Cl)CarbS]2 (M ¼ Rh (1a), Ir(1b)) was initially indicated by the NMR,
IR and elemental analysis, and 1a was further confirmed by the
X-ray crystallography. For 1a, the IR spectra show a strong band for

X.-K. Huo et al. / Journal of Organometallic Chemistry 695 (2010) 2007e2013
2009
Scheme 2. Synthesis of 1a, 1b.
2.4200(15) Å are a litter longer than that of Rh(1)eCl(1) 2.388(2) Å,
Rh(2)eCl(2) 2.375(2) Å, which are in agreement with previous
values for them in analogous complexes [45,46], The separation of
the Ir(1)eCl(1), Ir(1)eS(1), Ir(2)eCl(2, Ir(2)eS(1) are in agreement
with these of analogous complexes [47,48].
were also confirmed, respectively (in experiment section). 11B NMR
spectra exhibit resonances at
ꢀ1.9, ꢀ4.4, ꢀ9.1,ꢀ11.3 ppm. These
d
spectroscopic data and the combustion analyses for H and C indi-
cate the formation of a new complex Cp*Rh(Cl)(BunPPh2)CarbS,
which was further confirmed by the X-ray crystallography. An
analog Ir complex 2b was prepared by the same synthetically
method. And a comprehensive analysis of the spectroscopic data
(IR, 1H NMR, and 11B NMR) also shows the structure is analogous to
2a, which was demonstrated by the X-ray crystallography.
The crystallographic data for complex 2a and 2b are summa-
rized in Table 1; An ORTEP drawing of complex 2a, 2b and selected
bonds and angles are shown in Figs. 3 and 4, respectively. The solid
state molecular structure reveals the geometry at the Rh(III) center
is a three-legged piano-stool shape with Rh atom coordintated by
the h5-Cp*, one CarbS ligands, one phosphorus atom and one
chloride atom, consequently it can be described as pseudo-octa-
hedron in which h5-Cp* group occupies three fac coordination side.
Within our expectation, the coordination environment and crystal
structure of Ir(III) centre are analogous to that of Rh(III) centre. The
Ir (III) center is also a three-legged piano-stool with Ir atom coor-
dinated by the h5-Cp*, one CarbS ligand, one phosphorus atom and
one chloride atom. The distances Rh(1)eS(1) 2.3848(9) Å, Rh(1)eP
(1) 2.3157(10) Å are a litter shorter than that of Rh(1)eCl(1) 2.4122
(9) Å, which are all within the range of known values for them in
analogous complexes [10,31,49]. And the lengths Ir(1)eP(1) 2.2998
(13) Å, Ir(1)eS(1) 2.3821(12) Å and Ir(1)eCl(1) 2.4088(12) Å, are all
comparable to those reported for the Ir(III) complexes with P,S-
ligands [48].
2.3. Synthesis and characterization of the mononuclear complexes
Cp*M(Cl)(BunPPh2)CarbS (M ¼ Rh (2a), Ir (2b)) and Cp*M (BunPPh2)
CarbS(PF6) (M ¼ Rh (3a), Ir (3b))
A fresh kind of metal complexes with the chemical formula
Cp*M(PMe3)Cl(S-Dmp) (M ¼ Ir, Rh) were recently reported by
K. Tatsumi and co-workers [9,10]. They have excellent capabilities
of the activation of dihydrogen and can also help us understand the
mechanism of [NiFe] hydrogenases. Based on these results, two
new o-carboranyl compounds (2a and 2b) coordinated by sulfur,
phosphorous atoms were designed and synthesized, which may be
also good precursors to reproduce the mechanism of [NiFe]
hydrogenases through the activation of dihydrogen at metal sulfur
site. 2a and 2b were obtained from the reactions of 1a or 1b with
BunPPh2 in toluene in moderate yields, as shown in Scheme 1.
The complexes (2a and 2b) were obtained from recrystallization
in form of air- and moist-stable, red, transparent prisms when the
low temperature was applied. For 2a, the IR spectra show a strong
band for BeH vibration at approximately 2583 cmꢀ1, the formation
is also confirmed by the appearance of 1H NMR signals at
4
d
1.36 ppm with J(PH) ¼ 1.6 Hz, which can be ascribed to the Cp*
groups. The 1H NMR signals of HeCcage, ePPh2 and BunPPh2 groups
Table 1
Crystallographic Data and Structure Refinement Parameters for 1a, 1b, 2a, 2b and 4b.
1a
1b$0.5CH2Cl2
2a
2b$0.5CH2Cl2
4b
Empirical formula
Formula weight
Crystal syst.
Space group
a (Å)
C
24H52B20Cl2S2Rh2
C25H54B20Cl4S2 Ir2
1161.20
Orthorhombic,
Pnma
16.987(6)
18.503(6)
14.119(5)
90
C28H45B10ClPRhS
691.13
Monoclinic
C2/c
34.153(11)
10.620(3)
20.173(6)
90
104.187
90
7094(4), 8
1.294
0.680
C28.5H46B10Cl2IrPS
822.88
Monoclinic
C2/c
33.921(12)
10.697(4)
20.256(7)
90
103.899(5)
90
C30H41B10ClIrPS
800.41
Monoclinic,
P2(1)/c
897.70
Orthorhombic
Pnma
17.057(10)
8.286(11)
14.431(9)
90
9.013(3)
b (Å)
c (Å)
18.281(6)
21.619(8)
90
99.772(4)
90
3510(2), 4
1.514
4.006
a
b
g
(ꢁ)
(ꢁ)
(ꢁ)
90
90
90
90
volume (Å3), Z
4501(5), 4
1.325
0.963
4438(3), 4
1.738
6.348
7135(4), 8
1.532
4.017
Dc(g cmꢀ3
(Mo K
) (mmꢀ1
F(000)
range (ꢁ)
Limited indices
Reflections/unque [R(int)]
Completeness to
(ꢁ)
)
m
a
)
1808
2232
2848
3272
1584
q
1.80e27.90
ꢀ15,22; ꢀ22,23; ꢀ16,18
21414/5292 [0.1049]
27.90 (95.6%)
5294/0/257
0.914
1.81e27.01
ꢀ21,18; ꢀ20,23; ꢀ15,17
20551/4937 [0.0415]
27.01(98.9%)
4937/0/273
0.930
2.01e27.01
ꢀ43,38; ꢀ12,13; ꢀ16,25
16487/7558 [0.0355]
27.01 (97.4%)
7558/0/399
0.985
2.00e27.01
ꢀ41,43; ꢀ11,13; ꢀ25,20
16777/7641 [0.0352]
27.01 (97.9%)
7641/0/413
0.974
1.47e27.01
ꢀ11,11; ꢀ22,14; ꢀ27,27
16494/7515 [0.0534]
27.01(97.9%)
7515/0/416
0.972
q
Data/restraints/parameters
Goodness-of-fit on F2
R1, wR2 [I > 2
s
(I)]a
0.0491, 0.0978
0.0866, 0.1033
0.0262, 0.0582
0.0423, 0.0623
0.0350, 0.0803
0.0618, 0.0897
0.0323, 0.0625
0.0512, 0.0659
0.0390, 0.0864
0.0560, 0.0906
R1, wR2 (all data)
P
P
P
a
R1
¼
jjF0jejFcjj (based on reflections with F2o > 2
s
F2) 2. wR2 ¼ [ [w(Fo2 ꢀ F2c)2]/ [w(F2o)2]]1/2; w ¼ 1/[
s
2(Fo2) þ (0.095P)2]; P ¼ [max(Fo2, 0) þ 2Fc2]/3 (also with Fo2 > 2
s
F2).

2010
X.-K. Huo et al. / Journal of Organometallic Chemistry 695 (2010) 2007e2013
Fig. 3. ORTEP drawing of 2a with thermal ellipsoids drawn at the 30% level, all
hydrogen atoms were omitted for clarity. Selected bond lengths (Å) and angles (ꢁ): Rh
(1)eP(1) 2.3157(10), Rh(1)eS(1) 2.3848(9), Rh(1)eCl(1) 2.4122(9), P(1)eRh(1)eS(1)
81.94(3), P(1)eRh(1)eCl(1) 89.59(3), P(1)eRh(1)eCl(1) 89.59(3).
Fig. 1. ORTEP drawing of 1a with thermal ellipsoids drawn at the 30% level, all
hydrogen atoms were omitted for clarity. Selected bond lengths (Å) and angles (ꢁ): Rh
(1)eCl(1) 2.388(2), Rh(1)eS(1) 2.4212(15), Rh(2)eCl(2) 2.375(2), Rh(2)eS(1) 2.4200
(15); Cl(1)eRh(1)eS(1) 95.77(4), S(1)eRh(1)eS(1A) 78.13(7), Cl(2)eRh(2)eS(1) 94.07
(4), S(1A) eRh(2)eS(1) 78.17(7).
4b) coordinated by sulfur, phosphorous atoms were synthesized. 4a
and 4b were obtained directly from the reactions of 1a or 1b with
PPh3 in toluene in moderate yields, as shown in Scheme 1.
3a and 3b can be easily obtained by treatment of 2a and 2b with
1.2 equiv AgPF6 in CH2Cl2, and purified by recrystallization with
CH2Cl2/hexane, whose structures were characterized by IR 1H NMR
and elemental analysis. Comparing with the 2a and 2b, the spectra
of IR suffer a minor change and the 1H NMR shift to a litter low field
The complexes (4a and 4b) were obtained from recrystallization
in form of air- and moist-stable, red, transparent prisms at ꢀ18 ꢁC.
For 4a, the IR spectra show a strong band for BeH vibration at
approximately 2573, 2551, 2529 cmꢀ1, the formation is also
1
(the H NMR of the Cp* shift from 1.36 to 1.87 ppm for the trans-
confirmed by the appearance of 1H NMR signals at 1.42 with the 4J
d
formation from 2a to 3a). Complex 3a and 3b were found to be
readily soluble in CH2Cl2, CHCl3 and acetonitrile, soluble in alcohols,
and partially soluble in ether, toluene and THF, insoluble in hexane.
(PH) ¼ 4.0 Hz, 4.36, 7.47e7.61 and 7.79e7.81 ppm, which can be
ascribed to the Cp* groups, CcageeH, and phenyl (PPh2,PPh3),
respectively. 11B NMR spectra exhibit resonances at
ꢀ8.9,ꢀ13.4 ppm.
d
ꢀ3.6, ꢀ4.4,
2.4. Synthesis and characterization of Cp*M(Cl)(PPh3)CarbS
(M ¼ Rh (4a), Ir (4b)) and Cp*M(PPh3)CarbS(PF6) (M ¼ Rh (5a), Ir
(5b))
These spectroscopic data and the combustion analyses for H and
C indicate the formation of a new complex Cp*Rh(Cl)(PPh3)CarbS. In
order to unambiguously elucidate the detailed cluster structures,
the 4b was also studied by the single crystal X-ray diffraction.
The crystallographic data for complex 4b are summarized in
Table 1; An ORTEP drawing of complex 4b and selected bonds and
angles are shown in Fig. 5. The solid state molecular structure
reveals the geometry at the Ir(III) center are analogous to these of
In order to systemically investigate the dihydrogen activation
driven by the half-sandwich Rh, Ir complexes bearing the P, S
coordinated atoms, another two o-carboranyl compounds (4a and
Fig. 2. ORTEP drawing of 1b with thermal ellipsoids drawn at the 30% level, all
hydrogen atoms were omitted for clarity. Selected bond lengths (Å) and angles (ꢁ): Ir
(1)eCl(1) 2.3940(16), Ir(1)eS(1) 2.4016(12), Ir(2)eCl(2) 2.3889(16), Ir(2)eS(1) 2.4047
(12); Cl(1)eIr(1)eS(1) 94.27(4), S(1A)eIr(1)eS(1) 77.01(6), S(1)eIr(2)eS(1A) 76.90(5),
Ir(1)eS(1)eIr(2) 102.26(5).
Fig. 4. ORTEP drawing of 2b with thermal ellipsoids drawn at the 30% level, all
hydrogen atoms were omitted for clarity. Selected bond lengths (Å) and angles (ꢁ): Ir
(1)eP(1) 2.2998(13), Ir(1)eS(1) 2.3821(12), Ir(1)eCl(1) 2.4088(12), P(1)eIr(1)eS(1)
82.30(4), P(1)eIr(1)eCl(1) 89.63(4), S(1)eIr(1)eCl(1) 100.65(5).

X.-K. Huo et al. / Journal of Organometallic Chemistry 695 (2010) 2007e2013
2011
The vacant coordination sites at the metal center in these
complexes were also obtained easily. Although the preliminary
experiments on the dihydrogen activation induced by these half-
sandwich Rh, Ir complexes were not exciting, further experiments
under harsh conditions or under the conditions of other anion will
be expected in the near future.
4. Experimental
4.1. Materials and instrumentation
All manipulations were carried out under a nitrogen atmosphere
using standard Schlenk techniques, unless otherwise stated.
Solvents were distilled under nitrogen from sodium benzophenone
(hexane, diethyl ether, THF, dimethoxyethane (CH3OCH2CH2OCH3,
DME)) or calcium hydride (dichloromethane). The starting materials
[Cp*MCl(
m
-Cl)]2 (M ¼ Ir, Rh) [51] and 1-(lithiumthiolato)-1,2-
Fig. 5. ORTEP drawing of 4b with thermal ellipsoids drawn at the 30% level, all
hydrogen atoms were omitted for clarity. Selected bond lengths (Å) and angles (ꢁ): Ir
(1)eP(1) 2.3082(13), Ir(1)eS(1) 2.3734(15), Ir(1)eCl(1) 2.4104(16); P(1)eIr(1)eS(1)
86.00(5), P(1)eIr(1)eCl(1) 87.26(5), S(1)eIr(1)eCl(1) 101.13(5).
dicarba-closo-dodecaborate (LiCarbS) [44], and BunPPh2 [52] were
synthesized according to the literature. Other chemical reagents
were obtained from commercial sources and used without further
purification. 1H NMR (400 MHz), and 11B NMR (160 MHz) spectra
were obtained on a VAVCE DMX-400 spectrometer. Elemental
analysis was performed on an Elementar vario EL III analyzer. IR
(KBr) spectrawererecordedon the Nicolet FT-IR spectrophotometer.
2b except that the BunPPh2 was substituted by the PPh3. The
coordination environment of metal centers are pseudo-octahedron,
coordinated by the h5-Cp*, one CarbS ligands, one phosphorus atom
and one chloride atom. The distances Rh(1)eS(1) 2.3855(10) Å, Rh
(1)eP(1) 2.3291(9) Å are all within the range of known values for
them in analogous complexes [10,31]. And the lengths Ir(1)eP(1)
2.3082(13) Å, Ir(1)eS(1) 2.3734(15) Å and Ir(1)eCl(1) 2.4104(16) Å,
are all comparable to those reported for the Ir(III) complexes with
P,S-ligands [49,50].
5a and 5b were also obtained by treatment of 4a and 4b with
1.2 equiv AgPF6 in CH2Cl2, and purified by recrystallization with
CH2Cl2/hexane, which were supported by IR, 1H NMR and
elemental analysis. Comparing with the corresponding starting
materials, the spectra of IR suffer a minor change but the 1H NMR of
the Cp* shift to low field a little. Complex 5a and 5b were found to
be soluble in most chlorinated solvents and alcohols, as well as in
acetonitrile, insoluble in hexane, and partially soluble in ether,
toluene and THF.
4.2. Synthesis of complex 1a
[Cp*RhCl(
m-Cl)]2 (154.5 mg, 0.25 mmol) was added to the
solution of LiCarbS (91 mg, 0.5 mmol) in THF (10 mL) at 0 ꢁC. Then
the solution was stirred for 24 h at room temperature. The solution
gradually turned dark red suggesting a formation of [Cp*Rh(Cl)
CarbS]2 complex. The solvent was removed under reduced pressure,
and the residue was extracted with toluene (20 mL ꢂ 2) and the
solution was centrifuged to remove LiCl. After removal of the
solvent under vacuum, the dark red solid was washed with hexane
(5 mL ꢂ 2) and dried. Fine red crystals of 1a (94.3 mg, 42%) were
obtained through recrystallization from CH2Cl2ehexane at ꢀ18 ꢁC.
Anal. Calcd for C24H52B20Cl2S2Rh2: C, 32.1%; H, 5.84%. Found: C,
32.3%; H, 5.88%. IR (KBr, disk):
y
(cmꢀ1), 2921 (CeH), 2589, 2563
1.63 (s, 30H, Cp*), 3.56 (s,
(BeH). 1H NMR (400 MHz, CDCl3, ppm):
d
2H, CcageeH). 11B NMR (160 MHz, CDCl3, ppm):
(2B), ꢀ7.1 (3B), ꢀ9.0 (1B), ꢀ11.3 (3B).
d
ꢀ2.5 (1B), ꢀ4.4
2.5. The study of the model complexes for heterolytic dihydrogen
activation at metal sulfur site
4.3. Synthesis of complex 1b
From the description of these complexes, only in the view of the
structures of 3a, 3b, 5a and 5b, they are unsaturated and have
a vacant coordination site at the metal center, which may offer
a chance to bind H2 to the metal center. However, when the H2 gas
(1 atm) was bubbled into the Schlenk of 3a, 3b or 5a, 5b in CH2Cl2 at
room temperature or at 0 ꢁC, 1H NMR of the products don’t exhibit
any corresponding signals about heterolytic dihydrogen activation.
Although the results are not exciting, the research on the hetero-
lytic dihydrogen activation driven by these complexes using other
anions such as B(C6F5)4, BF4 or at harsh conditions (at ꢀ80 ꢁC or
refluxed temperature in toluene) is still in progress.
The synthetic procedure is analogous to that of 1a. [Cp*IrCl
(
m
-Cl)]2 (197 mg, 0.25 mmol) was added to solution of LiCarbS
(91 mg, 0.5 mmol) inTHF (10 mL) at 0 ꢁC. And solutionwas stirred for
24 h at room temperature with the color gradually turning red. The
solvent was removed in vacuo, and the residue was extracted by
toluene (20 mL ꢂ 2) and the solutionwas centrifuged to remove LiCl.
After removal of the solvent under vacuum, the red or yellowish
solid was washed with hexane (2 ꢂ 5 mL) and dried. Fine red crystals
of 1b (96.9 mg, 36%) were obtained through recrystallization from
CH2Cl2ehexane at ꢀ18 ꢁC. Anal. Calcd for C24H52B20Cl2S2Ir2: C,
26.78%; H, 4.87%. Found: C, 26.85%; H, 4.91%. IR (KBr, disk):
2953 (CeH), 2593, 2568 (BeH). 1H NMR (400 MHz, CDCl3, ppm):
1.37 (s, 30H, Cp*), 3.48 (s, 2H, CcageeH). 11B NMR (160 MHz, CDCl3,
ppm):
ꢀ1.7 (2B), ꢀ7.9 (2B), ꢀ8.8 (4B), ꢀ10.9 (2B).
y
(cmꢀ1),
3. Conclusions
d
Aimed to synthesize carboranyl complexes coordinated by
hetero atoms and to systemically investigate their application on
dihydrogen activation, a series of monothiolate ortho-carboranyl
half-sandwich Rh, Ir complexes have been synthesized and fully
characterized. Determined by X-ray analysis, their structures
revealed that they are binuclear, mononuclear complexes coordi-
nated by hetero atoms (Sulfur and Phosphorus atoms), respectively.
d
4.4. Synthesis of complex 2a
To a solution of 1a (224.5 mg, 0.25 mmol) in toluene (15 mL) was
added a solution of BunPPh2 (121.7 mg, 0.5 mmol) in toluene (5 mL)
at 0 ꢁC and the mixture was stirred at room temperature for 12 h to

2012
X.-K. Huo et al. / Journal of Organometallic Chemistry 695 (2010) 2007e2013
give a dark red solution. The solvent was removed under vacuum
and the residue was washed with hexane (5 mL) twice to afford 2a
as a red powder (197.1 mg, 57%). Crystals suitable for X-ray crys-
tallography were grown from a CH2Cl2/hexane solution at room
temperature. Anal. Calcd for C28H45B10ClPRhS: C, 48.66%; H, 6.56%.
was washed with hexane (5 mL) twice to afford 2a as a red powder
(174.2 mg, 49%). Crystals suitable for X-ray crystallography were
grown from a CH2Cl2/hexane solution at room temperature. Anal.
Calcd for C30H41B10ClPSRh: C, 50.67%; H, 5.81%. Found: C, 50.59%; H,
5.90%. IR (KBr, disk):
y
(cmꢀ1), 2552, 2520. 1H NMR (400 MHz,
Found: C, 48.74%; H, 6.61%. IR (KBr, disk):
y
(cmꢀ1), 2937 (CeH),
0.85 (m, 3H, eCH3),
CDCl3, ppm):
d
1.42 (d, 15H, Cp*, 4J(PH) ¼ 4.0 Hz), 4.36 (s, 1H,
2583 (BeH). 1H NMR (400 MHz, CDCl3, ppm):
d
CcageeH), 7.47e7.61 (m, 18H, phenyl), 7.79e7.81 (m, 12H, phenyl).
1.25 (m, 4H, eCH2), 1.36 (d, 15H, Cp*, 4J(PH) ¼ 1.6 Hz), 1.52 (m, 2H,
11B NMR (160 MHz, CDCl3, ppm)
d
ꢀ3.6 (1B), ꢀ4.4 (3B), ꢀ8.9
eCH2), 4.35 (s, 1H, CcageeH), 7.47e7.61 (m, 6H, phenyl), 7.79e7.81
(2B),ꢀ13.4 (4B).
(m, 4H, phenyl). 11B NMR (160 MHz, CDCl3, ppm)
d
ꢀ1.9 (1B), ꢀ4.4
(3B), ꢀ9.1 (2B),ꢀ11.3 (4B).
4.9. Synthesis of complex 4b
4.5. Synthesis of complex 2b
A procedure analogous to the preparation of 4a was used. To
a solution of 1b (269.1 mg, 0.25 mmol) in toluene (15 mL) was
added the solution of PPh3 (131.1 mg, 0.5 mmol) in toluene (5 mL) at
0 ꢁC and the mixture was stirred at 60 ꢁC for 8 h to give a dark red
solution. The solvent was removed under vacuum and the residue
was washed with hexane (5 mL) twice to afford 4b as a red powder
(232.1 mg, 58%). Crystals suitable for X-ray crystallography were
grown from a CH2Cl2/hexane solution at room temperature. Anal.
Calcd for C30H41B10ClPSIr: C, 45.01%; H, 5.16%. Found: C, 45.07%; H,
A procedure analogous to the preparation of 2a was used. To
a solution of 1b (269.1 mg, 0.25 mmol) in toluene (15 mL) was
added the solution of BunPPh2 (121.7 mg, 0.5 mmol) in toluene
(5 mL) at 0 ꢁC and the mixture was stirred at room temperature for
12 h to give a dark red solution. The solvent was removed under
vacuum and the residue was washed with hexane (5 mL) twice to
afford 2b as a red powder (241.9 mg, 62%). Crystals suitable for X-
ray crystallography were grown from a CH2Cl2/hexane solution at
room temperature. Anal. Calcd for C28H45B10ClIrPS: C, 43.09%; H,
5.24%. IR (KBr, disk):
(400 MHz, CDCl3, ppm):
y
, 2933 (CeH), 2559 cmꢀ1 (BeH). 1H NMR
d
1.47 (d, 15H, Cp* 4J(PH) ¼ 3.6 Hz), 4.30 (s,
5.81%. Found: C, 43.77%; H, 6.64%. IR (KBr, disk):
y
, 2933 (CeH),
0.78 (m, 3H,
1H, CcageeH), 7.47e7.78 (m, 25H, phenyl). 11B NMR (160 MHz,
2569 cmꢀ1 (BeH). 1H NMR (400 MHz, CDCl3, ppm):
d
CDCl3, ppm)
d
ꢀ3.2 (1B), ꢀ4.4 (2B), ꢀ8.7 (4B),ꢀ12.2 (3B).
eCH3), 1.27 (m, 4H, eCH2), 1.50 (m, 2H, eCH2), 1.54 (d, 15H, Cp*, 4J
(PH) ¼ 2.2 Hz), 4.33 (s, 1H, CcageeH), 7.47e7.78 (m, 10H, phenyl).
4.10. Synthesis of complex 5a
11B NMR (160 MHz, CDCl3, ppm)
d
ꢀ0.9 (1B), ꢀ3.0 (1B), ꢀ8.9 (6B),
ꢀ12.1 (2B).
Complex 4a (89.7 mg, 0.1 mmol) and AgPF6 (55.6 mg,
0.22 mmol) were charged into a schlenk tube. To this tube was
added CH2Cl2 (10 mL) and the mixture was stirred at room
temperature in dark for 4 h. The color of the solution was changed
to purple or dark from the red. The solution was filtrated and the
solvent was removed under reduced pressure. After washing with
hexane (5 mL), the green solid was obtained (63.1 mg, 77%). Anal.
Calcd for C30H41B10P2RhSF6: C, 43.90%; H, 5.04%. Found: C, 43.82%;
4.6. Synthesis of complex 3a
Complex 2a (69.1 mg, 0.1 mmol) and AgPF6 (30.3 mg,
0.12 mmol) were charged into a schlenk tube. To this tube was
added CH2Cl2 (10 mL) and the mixture was stirred at room
temperature in dark for 4 h. The color of the solution was changed
to purple or dark from the red. The solution was filtrated and the
solvent was removed under reduced pressure. After washing with
hexane (5 mL), the green solid was obtained (66.4 mg, 83%). Anal.
Calcd for C28H45B10F6P2RhS: C, 42.00%; H, 5.66%. Found: C, 42.07%;
H, 5.10%. IR (KBr, disk):
y
(cmꢀ1), 2943 (CeH), 2573, 2551, 2529
(BeH). 1H NMR (400 MHz, CDCl3, ppm):
d
1.63 (d, 15H, Cp*, 4J
(PH) ¼ 2.4 Hz), 4.43 (s, 1H, CcageeH), 7.39e7.83 (m, 25H, phenyl). 11
B
NMR (160 MHz, CDCl3, ppm):
d
ꢀ2.9 (1B), ꢀ4.6 (1B), ꢀ7.9 (3B), ꢀ9.6
H, 5.72%. IR (KBr, disk):
y
, 2956 (CeH), 2583 cmꢀ1 (BeH). 1H NMR
(3B), ꢀ13.4 (2B).
(400 MHz, CDCl3, ppm):
d 0.89 (m, 3H, eCH3), 1.33 (m, 2H, eCH2),
1.67 (m, 4H, eCH2), 1.87 (d, 15H, Cp*, 4J(PH) ¼ 4.0 Hz), 4.31 (s, 1H,
4.11. Synthesis of complex 5b
C
cageeH), 7.49e7.84 (m, 10H, phenyl). 11B NMR (160 MHz, CDCl3,
ppm)
d
ꢀ3.7 (1B), ꢀ6.5 (1B), ꢀ8.7 (3B), ꢀ11.4 (4B), ꢀ12.9 (1B).
The synthetic procedure is analogous to that of 5a. Complex 4b
(80.0 mg, 0.1 mmol) and AgPF6 (30.3 mg, 0.12 mmol) were charged
into a schlenk tube in CH2Cl2 (15 mL). The green solution was fil-
trated and the solvent was removed and the green solid was iso-
lated (64.6 mg, 71%). Anal. Calcd for C30H41B10P2IrSF6: C, 39.60%; H,
4.7. Synthesis of complex 3b
The synthetic procedure is analogous to that of 3a. Complex 2b
(78.1 mg, 0.1 mmol) and AgPF6 (30.3 mg, 0.12 mmol) were charged
into a schlenk tube in CH2Cl2. The green solution was filtrated and
the solvent was removed and the green solid was isolated (77.4 mg,
87%). Anal. Calcd for C28H45B10F6P2SIr: C, 37.79%; H, 5.10%. Found: C,
4.54%. Found: C, 39.57%; H, 4.59%. IR (KBr, disk):
y
(cmꢀ1), 2932
1.72 (d,
(CeH), 2572, 2554 (BeH). 1H NMR (400 MHz, CDCl3, ppm):
d
15H, Cp*, 4J(PH) ¼ 4.6 Hz), 4.54 (s, 1H, CcageeH), 7.47e7.84 (m, 25H,
phenyl). 11B NMR (160 MHz, CDCl3, ppm):
ꢀ9.6 (3B), ꢀ12.2 (1B), ꢀ13.4 (4B).
d
ꢀ2.7 (1B), ꢀ5.5(1B),
37.85%; H, 5.16%. IR (KBr, disk):
NMR (400 MHz, CDCl3, ppm):
y
, 2955 (CeH), 2579 cmꢀ1 (BeH). 1H
d
0.89 (m, 3H, eCH3), 1.37 (m, 4H,
eCH2),1.53 (m, 4H, eCH2),1.79 (d,15H, Cp*, 4J(PH) ¼ 2.8 Hz), 4.36 (s,
4.12. X-ray diffraction study
1H, CcageeH), 7.49e7.83 (m, 10H, phenyl).11B NMR (160 MHz, CDCl3,
ppm)
d
ꢀ1.9 (1B), ꢀ4.4 (1B), ꢀ7.3 (2B), ꢀ8.4 (4B), ꢀ12.7 (2B).
Diffraction data of 1a, 1b, 2a, 2b and 4b were collected on
a Bruker Smart APEX CCD diffractometer with graphite-mono-
4.8. Synthesis of complex 4a
chromated Mo K
a
radiation (
l
¼ 0.71073 Å). All the data were
collected at room temperature and the structures were solved by
direct methods and subsequently refined on F2 by using full-matrix
least-squares techniques (SHELXL) [53], SADABS [54] absorption
corrections were applied to the data. All the non-hydrogen atoms
were refined anisotropically, and hydrogen atoms were located at
To a solution of 1a (224.5 mg, 0.25 mmol) in toluene (15 mL) was
added a solution of PPh3 (131.1 mg, 0.5 mmol) in toluene (5 mL) at
0 ꢁC and the mixture was stirred at at 60 ꢁC for 8 h to give a dark red
solution. The solvent was removed under vacuum and the residue

X.-K. Huo et al. / Journal of Organometallic Chemistry 695 (2010) 2007e2013
[18] S. Liu, G.-L. Wang, G.-X. Jin, Dalton. Trans. (2008) 425.
2013
calculated positions except the hydrogen atoms of carborane
(CcageeH of 1a, 1b, 2a, 2b and 4b) were found by difference Fourier
Method. There are disordered solvent molecules in the crystal of 2a,
which can not be solved properly. Hence the SQUEEZE algorithm
was used to omit them and the crystal data was refined to
convergence. A summary of the crystallographic data and selected
experimental information are given in Table 1.
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CCDC 769186e769190 contain the supplementary crystallo-
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