Synthesis and characterization of new 10- and 12-vertex CO-ligated metallathiaboranes

Article abstract of DOI:10.1016/j.jorganchem.2012.04.003

The reaction between [arachno-6-SB₉H₁₂]^- and [IrCl(CO)(PMe₃)₂] affords the previously reported 11-vertex cluster, [8,8,8-(CO)(PMe₃)₂-arachno-8,7- IrSB₉H₁₀] (4), and small amounts of the new 10-vertex iridathiaborane [9,9,9,9-(CO)(H)(PMe₃)₂-arachno-9,6- IrSB₈H₁₀] (5). Alternatively, a rational synthesis of iridathiadecaboranes is effected from the reaction of the 9-vertex anion [arachno-4-SB₈H₁₁]^- with [MCl(CO)(PPh ₃)₂], to afford new CO-ligated 10-vertex metallathiaboranes of formulation, [9,9,9,9-(CO)(H)(PPh₃) ₂-arachno-9,6-MSB₈H₁₀], where M = Rh (6) and Ir (7), in useful yields of 61% and 60% respectively. Treatment of the 11-vertex rhodathiaborane, [8,8-(PPh₃)₂-8,7-nido-RhSB ₉H₁₀] (1) with nBuLi, followed by addition of [IrCl(CO)(PMe₃)₂] affords the 12-vertex iridarhodathiaborane, [1,2-(μ-CO)-1,1,2-(PMe₃)₃-2- (PPh₃)-closo-1,2-IrRhSB₉H₉] (8) in low yield (0.7%). The 10-vertex metallathiaboranes, 5, 6 and 7, and the bimetallic 12-vertex cluster, 8, have been characterized by multinuclear NMR spectroscopy. In addition, the molecular structures of compounds 5, 6, and 8 have been studied by X-ray diffraction.

Full text of DOI:10.1016/j.jorganchem.2012.04.003

Journal of Organometallic Chemistry 721-722 (2012) 23e30
Contents lists available at SciVerse ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Synthesis and characterization of new 10- and 12-vertex CO-ligated
metallathiaboranes
,
b
,
a
,
a
a
Susana Luaces a, Jonathan Bould a , Ramón Macías
, Rodrigo Sancho , Pilar García-Orduña ,
*
**
Fernando J. Lahoz a, Luis A. Oro a
a Instituto de Síntesis Química y Catálisis Homogénea (ISQCH), Universidad de Zaragoza-Consejo Superior de Investigaciones Científicas, Pedro Cerbuna 12, 50009 Zaragoza, Spain
Institute of Inorganic Chemistry of the Academy of Sciences of the Czech Republic, 25068 Husinec-Rez 1001, Czech Republic
b
ꢀ
ꢀ
a r t i c l e i n f o
a b s t r a c t
ꢀ
and [IrCl(CO)(PMe3)2] affords the previously reported 11-
vertex cluster, [8,8,8-(CO)(PMe3)2-arachno-8,7-IrSB9H10] (4), and small amounts of the new 10-vertex
Article history:
The reaction between [arachno-6-SB9H12
]
Received 6 March 2012
Received in revised form
30 March 2012
iridathiaborane [9,9,9,9-(CO)(H)(PMe3)2-arachno-9,6-IrSB8H10] (5). Alternatively, a rational synthesis of
ꢀ
iridathiadecaboranes is effected from the reaction of the 9-vertex anion [arachno-4-SB8H11
]
with
Accepted 2 April 2012
[MCl(CO)(PPh3)2], to afford new CO-ligated 10-vertex metallathiaboranes of formulation, [9,9,9,9-
(CO)(H)(PPh3)2-arachno-9,6-MSB8H10], where M ¼ Rh (6) and Ir (7), in useful yields of 61% and 60%
respectively. Treatment of the 11-vertex rhodathiaborane, [8,8-(PPh3)2-8,7-nido-RhSB9H10] (1) with
Dedicated to Professor Thomas P. Fehlner on
his 75th birthday. He has been a superb
mentor of many scientists around the world
working on “inorganometallic chemistry”.
nBuLi, followed by addition of [IrCl(CO)(PMe3)2] affords the 12-vertex iridarhodathiaborane, [1,2-(m-CO)-
1,1,2-(PMe3)3-2-(PPh3)-closo-1,2-IrRhSB9H9] (8) in low yield (0.7%). The 10-vertex metallathiaboranes, 5,
6 and 7, and the bimetallic 12-vertex cluster, 8, have been characterized by multinuclear NMR spec-
troscopy. In addition, the molecular structures of compounds 5, 6, and 8 have been studied by X-ray
diffraction.
Keywords:
Boron
Thiaborane
Metallathiaborane
Metallaborane
Carbonyl
Ó 2012 Elsevier B.V. All rights reserved.
Cluster
1. Introduction
for example, Scheme 1 illustrates the synthesis of the 10-vertex
ꢀ
thiaborane anion, [arachno-6-SB9H12
ane, arachno-4-SB8H12 [27,28].
]
and the 9-vertex thiabor-
The higher binary boron hydrides form polyhedral cluster
structures containing only boron and hydrogen atoms. The boron
centres in the cluster framework may be replaced by other
elements of the Periodic Table such as the p-block elements carbon,
nitrogen and sulphur to afford heteroboranes, or, in addition,
transition metals to give metallaborane or metallaheteroborane
compounds. Amongst the heteroboranes, the most extensively
studied are the carboranes and their metallacarboranes [1e16], but,
by comparison, the chemistry of other main-group polyhedral
hetero- and metallaheteroboranes is quite limited with some of the
more studies being the thiaboranes [17e26]. The development of
convenient synthetic routes to thiaborane clusters has aided this;
In recent years, we have been developing the organometallic
chemistry of the 11-vertex rhodathiaborane [8,8-(PPh3)2-nido-8,7-
RhSB9H10] (1), prepared from [RhCl(PPh3)3] and readily available Cs
[arachno-6-SB9H12], and its pyridine-ligated derivative [8,8,8-
(PPh3)2(H)-9-(NC5H5)-nido-8,7-RhSB9H9] (2) [29e32]. The latter
combines BeH terminal, BeHeB bridging and MeH sites in its
structure, which are quite rarely found in metallaboranes and
metallaheteroboranes (the majority incorporates BeH terminal,
and BeHeB and MeHeB bridging hydrogen atoms), conferring 2
with a rich reactivity. In this regard, 2 undergoes reversible dehy-
drogenation to give [1,1-(PPh3)2-3-(NC5H5)-closo-1,2-RhSB9H8] (3)
and, in conjunction with the reaction of 2 with ethylene, it defines
a catalytic cycle that operates in the hydrogenation of alkenes
[30,31]. The mode of action on these 11-vertex rhodathiaboranes is
reminiscent of non-innocent-ligand containing complexes that act
* Corresponding author. Instituto de Síntesis Química y Catálisis Homogénea
(ISQCH), Universidad de Zaragoza-Consejo Superior de Investigaciones Científicas,
Pedro Cerbuna 12, 50009 Zaragoza, Spain.
as catalyst promoters [33]. Thus, the {
SB9H8(NC5H5)} fragments in compounds 2 and 3, respectively, may
h -
4-SB9H9(NC5H5)} and {h6
** Corresponding author.
E-mail address: rmacias@unizar.es (R. Macías).
0022-328X/$ e see front matter Ó 2012 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2012.04.003

24
S. Luaces et al. / Journal of Organometallic Chemistry 721-722 (2012) 23e30
Scheme 1. Synthesis of thiaborane starting materials, used in this work.
be regarded as ligands that directly participate in the reactions,
thereby giving to the system a bifunctional acid/base character, as
shown by the heterolytic cleavage of H2 and its reactivity with
Brønsted acids [30,34].
{M(CO)(PPh3)2}þ fragment inserts between the BHB bridging
hydrogen atom and the {B(6)B(7)B(8} cluster face with the
{M(CO)(H)(PPh3)2} moiety becoming a new vertex.
These new CO-ligated metallathiaboranes, 5, 6 and 7, are char-
acterized by multielement NMR and IR spectroscopies, and mass
spectrometry. In addition, the molecular structures of 5 and 6 have
been determined by X-ray diffraction analyses (Fig. 1). Both clusters
exhibit a 10-vertex boat-type structure with the {M(H)(CO)(PR3)2}
Advances in organometallic and inorganometallic reaction
chemistry lie [35,36], in a large part, on the introduction of ligands
capable of bestowing a new reactivity on the transition metal
centres. Similarly, in metallaheteroboranes, the modification of the
coordination sphere around the metal centre, in order to tune its
reactivity, may be achieved by a variation of the heteroborane
fragment itself. Thus, as part of our interest in the search of new
metallathiaborane reaction chemistry, we describe reactions of
iridium and rhodium carbonyl complexes with [arachno-4-
SB8H11]ꢀ, which give H- and CO-ligated 10-vertex clusters that
fragment connected to the {h
3-SB8H10} assembly, as part of the
hexagonal {M(9)B(8)B(7)S(6)B(5)B(10)} face. Two hydrogen atoms
bridge the B(7)eB(8) and B(5)eB(10) edges. Both metal-
lathiaboranes exhibit the same stereochemistry around the metal
centre with a phosphine ligand [P(2) in Fig. 1] trans to the hydride,
which occupies an endo-position over the open face and the
carbonyl and the second phosphine, P(1), occupy exo-polyhedral
positions trans to the B(8) and B(10) vertices, respectively. The MeP
bonds are shorter for the iridium cluster as expected from the
contain a {h
3-SB8H10} fragment. Additionally, we, report here a new
12-vertex rhodium, iridium bimetallic cluster prepared from the
rhodathiaborane 1.
better s-donor capabilities of PMe3 vs. PPh3. The Rh(9)eP(2) and
2. Results and discussion
Ir(9)eP(2) bonds are 0.0888(5) and 0.0469(16) Å longer than the
M(9)eP(1) bonds, reflecting the strong trans influence of the
hydride ligand.
The structures of 5 and 6 resemble other crystallographic-
ally determined arachno-metalladecaboranes such as [6,6,6,6-
The caesium thiadecaborane salt, CsSB9H12, has proven to be
a very useful starting material for the synthesis of new metal-
lathiaboranes [26,37e41]. In particular, [8,8-(PPh3)2-nido-8,7-
RhSB9H10] (1) is prepared in high yield (90%) from the reaction
between the CsSB9H12 and [RhCl(PPh3)3] [42,43]. Following
a similar approach, we have recently prepared the CO-ligated
analogue, [8,8,8-(CO)(PMe3)2-nido-8,7-IrSB9H10] (4), using [IrCl(-
CO)(PMe3)2] as the metal complex in ca 70% yield [29]. However,
further investigation has revealed that the 10-vertex iridathiabor-
(PMe2Ph)2(CO)(H)-9-PPh3eIrB9H11
]
and [6,6-(Cp*)(CNEt)-9-
(CNEt)-RhB9H11] [45,46]. The molecular frameworks of all these
compounds are formally derived from an icosahedron by the
removal of two vertices, with the structures corresponding to
that expected for a 13 skeletaleelectron-pair (sep) arachno-
cluster with 10 vertices. Interestingly, the metallaboranes [6,6-
(PMe2Ph)2-9-(PMe2Ph)-MB9H11], where M ¼ Pt or Pd [47,48], and
platinathiaboranes [8-OEt-9,9-(PPh3)2-9,6-PtSB8H10] and [9,9-
(PPh3)2-9,6-PtSB8H10] [49], have 12 sep’s that correspond to 10-
vertex nido-structures. Formally, the 10-vertex boat-type cage is
obtained by the removal of the vertex of connectivity six of an
octadodecahedron and, therefore, the WilliamseWade cluster
geometry and electron-counting approach predicts the same 10-
vertex cluster geometry for frameworks with 12 or 13 sep’s
[50,51]. However, the presence of bridging hydrogen atoms
flanking B(5)B(10) and B(7)B(8) positions on the open face is
typical of ten-vertex arachno-polyhedral boron-containing
compounds [52e55]. And it has been recognized that metal-
laheteroboranes that incorporate {ML2}-metal fragments, where
M ¼ Rh(I), Ir(I), Pt(II) or Pd(II), deviate from the dictates of the
electron-counting rules [29,34,56].
ane [9,9,9,9-(CO)(H)(PMe3)2-arachno-9,6-IrSB8H10
] (5), is also
formed as a co-product (ca 7%) by a boron vertex cluster disman-
tling process (Scheme 2A). Methanol has the potential to act as
a deboronating agent, such as in the high yield synthesis of
[(PR3)2MB8H12] from the addition of [MCl2(PR3)2], where M ¼ Pt or
Pd, to KB9H14 in MeOH at ambient temperature [44]. Thus, if the
reaction of the salt CsSB9H12 with the metal complex is carried out
in MeOH together with [IrCl(CO)(PPh3)2] instead of [IrCl(-
CO)(PMe3)2], a ca 38% yield of two isomers of [(PPh3)2H(CO)-nido-
IrSB8H10] is obtained. The two isomers are based on different ligand
arrangements of the {Ir(CO)H(PPh3)2} moiety with respect to the
{SB8H10} cage, and separation of these very similar species in order
to more definitively characterise the isomers was too onerous to
achieve. We therefore undertook a direct rational synthesis from
the [arachno-4-SB8H11]
ꢀ anion and [IrCl(CO)(PPh3)2]. The [arachno-
4-SB8H12] precursor is conveniently prepared from CsSB9H12 and
may be deprotonated with MeLi. Thus deprotonation of the 9-
vertex thiaborane, arachno-4-SB8H12, with MeLi in ether and
subsequent addition of [MCl(CO)(PPh3)2], where M ¼ Rh and Ir,
afforded the corresponding 10-vertex metallathiaboranes, [9,9,9,9-
(CO)(H)(PPh3)2-arachno-9,6-MSB8H10], where M ¼ Rh (6) and Ir (7),
in good yields of 60 and 61% respectively (Scheme 2B). These
reactions can be described as the oxidative addition of the
The 11Be{1H} NMR spectra of the PPh3 ligated compounds, 6 and
7, show six signals of 1:1:2:2:1:1 relative intensity ratio. In the 1He
{
11B} NMR spectra, however, there are two sets of boron-bound
proton resonances due to the presence of two different isomers
in solution (Tables 1 and 2). The major isomer (ca. 88%) exhibits
eight BH terminal and two BHB bridging proton signals that
conform to the asymmetric structure found in the solid state;
whereas the minor isomer shows only three BH terminal and one
BHB bridging proton resonances, suggesting that the other
[SB8H11]
ꢀ anion to the square planar metal complexes; formally the

S. Luaces et al. / Journal of Organometallic Chemistry 721-722 (2012) 23e30
25
Scheme 2. Reactions of thiaboranes with square planar M(I) complexes of Rh and Ir.
expected BHt signals overlap with those of the major isomers, as it
is also found in the 11B NMR spectrum. The existence of a mixture of
isomers is further confirmed in the 31Pe{1H} spectrum, which for 6
exhibits two doublets of doublets for the major isomer at dP 13.5
and 28.4 ppm, and a doublet for the minor at 35.3 ppm; whereas for
7, the spectrum shows two singlets for the major isomer at dP 1.0
and ꢀ16.6 ppm, and a singlet at 6.4 ppm for the minor component.
In addition, the resonances of the MeH hydride ligands are found at
high field in the proton NMR spectra. Thus, diagnostic of the
stereochemistry around the metal as well as the commented
presence of two isomers, 6 exhibits a doublet of pseudo-triplets at
dH ꢀ14.65 ppm and a broad multiplet at ꢀ12.80 ppm in a 7:1
relative intensity ratio, corresponding to the asymmetric and
symmetric isomers, respectively. The large 2JPeH coupling constant
Fig. 1. Molecular structures of 5 (right) and 6 (left). Only the methyl groups in 5 and the carbon atoms of the ipso-carbons for the phenyl rings in 6 are shown for clarity. Selected
distances (Å) and interatomic angles (ꢁ) for 6 [with equivalent distances and angles for 5 in brackets] are as follow: Rh(9)eP(1) 2.3711(5) [2.3192(15)], Rh(9)eP(2) 2.4599(5)
[2.3661(16)], Rh(9)eC(1) 1.9095(19) [1.893(5)], Rh(9)eB(4) 2.241(2) [2.245(7)], Rh(9)eB(8) 2.288(2) [2.300(7)], Rh(9)eB(10) 2.302(2) [2.293(8)], Rh(9)eH(1) 1.55(3) [1.45(2)], C(1)e
O 1.136(3) [1.139(6)]. Angles (deg.):P(1)eRh(9)eP(2) 103.33(2) [97.84(5)], P(1)eRh(9)eC(1) 95.39(5) [95.14(16)], P(2)eRh(1)eC(1) 89.02(5) [89.77(17)], P(1)eRh(9)eH(1) 74.3(12)
[83(3)], P(2)eRh(9)eH(1) 176.1(13) [174(3)].

26
S. Luaces et al. / Journal of Organometallic Chemistry 721-722 (2012) 23e30
Table 1
Variable temperature NMR experiments between room
temperature and 120 ꢁC did not reveal interconversion between the
conformers suggesting that there is no dynamic equilibrium in
solution, and thus the transition state energy of a {M(CO)(H)(L)2}-
11B and 1He{11B} NMR data for 6 in CDCl3 at 293 K, compared to the corresponding
DFT/GIAO calculated 11B-nuclear shielding values in [brackets].
Assignmenta
d
(
11B) [DFT]
d
(1H) (minor)b
to-{h
3-SB8H10} conformational change in 6 and 7 is relative high.
B(4)
B(2)
B(6), B(10)
B(7), B(9)
B(3)
B(1)
30.9 [32.5]
14.4 [16.3]
5.52 (5.94)
3.65 (2.39)
2.75, 1.93 (2.13)
1.20, 1.70
1.40
1.02
The NMR data for the PMe3 ligated 5 reveal the presence of only
one isomer in solution with an asymmetric structure that matches
the stereochemistry found in the solid state (Fig. 1). In agreement
with this, the 31Pe{1H} NMR spectrum exhibits a pair of doublets at
ꢀ7.8[ꢀ6.5]
ꢀ18.1[ꢀ7.7,ꢀ9.8]
ꢀ27.8[-22.9]
ꢀ29.07[ꢀ27.9]
d
(
31P) ꢀ53.8 ppm (sharp) and ꢀ47.9 ppm (broad); whereas the 1
H
B(6)eHeB(7), B(9)eHeB(10)
RheH
ꢀ1.10,ꢀ2.23(ꢀ1.40)
ꢀ14.65c (ꢀ12.80)d
NMR spectrum shows a doublet of doublets at dH ꢀ13.69 ppm.
Assignments based on 1H{11B} selective experiments and DFT/GIAO calculated
11B chemical shielding data.
a
We have a current interest in bimetalladodecaborane clusters,
[(PMe2Ph)4M2B10H10] where M2 ¼ Pt2, PtPd, Pd2, as these have an
ability to reversibly sequester small molecules such as O2, CO and
b
The chemical shifts for the minor component are given in parenthesis.
RheH, dt JRheH ¼ 14 Hz, JPeH ¼ 173 Hz [P(2) trans to the hydride ligand]
c
1
2
2JPeH z 14 Hz [P(1) trans to the B(10) vertex].
SO2 to afford [(PMe2Ph)4(O2)M2B10H10], [(PMe2Ph)4(m-CO)
d
1
Broad signal that precludes the resolution of the multiplet: JRheH z 2(2JPeH
)
M2B10H10], etc. [57]. In changing the metal from Pt2 to Pd2, the
strength of the bonding of the small molecules to the metalemetal
vector weakens as shown by the infrared stretching frequency of
the bridging CO, with the trend being well modelled by density
functional theory (DFT) calculations as shown in Fig. 2. The system
comprises three components: the metal, the ligand, and the boron
cluster; each independently tuneable to achieve the desired
sensitivity of small molecule uptake and release. DFT calculation at
the B3LYP/6-31G*/LANL2DZ level show that, whereas changing the
metal from Pt to Pd would weaken the binding, an {IrRhSB9H9}
cluster would increase the binding strength (Fig. 2). It was therefore
of interest to prepare such a compound and to compare the
measured and calculated IR CO stretching frequency.
Thus, it is convenient to report here on a carbonyl ligated
bimetallathiaborane obtained from [8,8-(PPh3)2-8,7-RhSB9H10] 1.
The BHB bridging hydrogen atom in 1 undergoes deprotonation
with strong bases to afford the 11-vertex closo-anion, [8,8-(PPh3)2-
8,7-RhSB9H9]ꢀ [40], and this has the potential to react with other
metal complexes to produce 12-vertex bimetallathiadodecaborane
clusters. Treatment of 1 with nBuLi and the addition of [IrCl(-
CO)(PMe3)2], resulted in the isolation of the 12-vertex bimetallic
should give a pseudo-quartet.
of 173 Hz found for the major isomer, demonstrates that, as found
in the solid state, one of the PPh3 ligands is trans to the hydride
(Fig. 1); the pseudo-triplets indicate that the JPeH coupling
constant of the other phosphine, cis to the hydride ligand, is close to
the value of 14 Hz measured for the JRheH coupling constant. The
broadness of the hydride resonance of the minor symmetric isomer
arises probably because the coupling constants of the 1H hydride
with 103Rh and the two equivalent 31P nuclei of the PPh3 ligands are
similar.
2
1
The 1H NMR spectrum of 7 shows a doublet of doublets at
dH ꢀ15.24 ppm and a triplet at ꢀ13.05 ppm for the major and minor
isomer, respectively, in a 5:1 relative intensity ratio that resembles
the results found for the rhodathiaborane analogue, 6. These
spectroscopic data suggest that the isomers correspond to two
different conformations of the {M(CO)(H)(PPh3)2} vertex with
respect to the {h
3-SB8H10} fragment: one asymmetric (found in the
solid state) and the other with a Cs symmetry, schematics I and II.
iridarhodathiaborane,
[1,2-(m-CO)-1,1,2-(PMe3)3-2-(PPh3)-closo-
1,2-IrRhSB9H9] (8) in a low, 0.70%, yield (Scheme 3). The compound
is characterised by NMR and IR spectroscopies, and by a single
crystal X-ray diffraction study (Fig. 3) which show that there has
been ligand exchange between the PMe3 and PPh3 during the
reaction. The yield is low and the use of KHBEt3 as the deproto-
nating reagent or
a converse synthesis by the addition of
[(PPh3)3RhCl] to the anion of [8,8,8-(CO)(PMe3)2-8,7-IrSB9H10] 4
does not improve yield of the dimetallathiaborane.
Table 2
11B and 1He{11B} NMR data for 7 in CDCl3 at 293 K, compared to the corresponding
DFT/GIAO calculated 11B-nuclear shielding values in [brackets].
Assignmenta
d
(
11B) [DFT]
d
(1H) (minor)b
B(4)
B(2)
23.2 [28.8]
11.9 [12.9]
5.76 (6.23)
4.85
B(6), B(10)
B(7), B(9)
B(1)
B(3)
B(6)eHeB(7), B(9)eHeB(10)
IreH
ꢀ8.7[ꢀ7.2, ꢀ8.8]
ꢀ26.2[ꢀ11.3,ꢀ12.7]
ꢀ31.2[ꢀ27.5]
ꢀ32.8 [ꢀ29.6]
2.07, 2.88
1.88, 1.18
1.72
1.28
ꢀ2.25, ꢀ3.30 (ꢀ2.60)
ꢀ15.24c (ꢀ13.05d)
a
Assignments based on 1H{11B} selective experiments and DFT/GIAO calculated
Fig. 2. Measured (lower line) and DFT-calculated (upper line) infrared stretching
frequencies of the Pt2B10eCO, PtPdB10eCO and Pd2B10eCO, (from reference [57])
plotted against the B3LYP/6-31G*/LANL2DZ calculated CeO distance together with CO
group in IrRhSB9eCO (8) with the binding strength of the metalemetal vector to the
CO molecules increasing to the right.
11B chemical shielding data.
b
The chemical shifts for the minor component are given in parenthesis.
c
2
dd, 2JPeH ¼ 145 Hz JPeH ¼ 20 Hz.
d
t, 2JPeH ¼ 13 Hz.

S. Luaces et al. / Journal of Organometallic Chemistry 721-722 (2012) 23e30
27
Scheme 3.
Compound 8 is a new member in the series of 12-vertex met-
Cl-ligated bimetallic clusters,
9
and 11, to the distances of
allathiaboranes built upon the {SB9H9} scaffold [26,37,38,42,
2.7409(10) and 2.7583(4) Å of the CO-ligated counterparts, 8 and
10, respectively. The -CO-to-{IreRh} linkage in 8 is asymmetric
with the CeIr distance 0.057(4) Å shorter than the corresponding
CeRh length: this may reflect a higher electron density at the
iridium centre.
It is noteworthy that in 8, the RheP bond distances of the
phosphine ligands trans to the sulphur vertex [P(2) and P(4) in
Fig. 1] are shorter than the corresponding RheP bond lengths of the
PR3 ligands that lie trans to the B(6) vertex [P(1) and P(3) in Fig. 1].
This suggests a higher trans influence of a BeH unit vs. a sulphur
vertex. This fact has also been observed in 1, and in 11-vertex nido-
hydridorhodathiaborane derivatives [29,31].
58e60]. Among these bimetallic clusters, the rhodathiabor-
m
anes,
2,3,1-Rh2SB9H8] (9) [42], [2,3e(CO)2e2,3-(
closo-2,3,1-Rh2SB9H9] (10) [59] and [2,3-(Cl)2-2,3-(
3,7-( -dppm)-closo-2,3,1-Rh2SB9H8] (11) [60], have been crystal-
[2-(Cl)-2,3-(
m
-Cl)-2,3-(PPh3)2-3-(3,7-
m
C,P(C6H4PPh2)-closo-
m-CO)e2,3-(PPh3)2-
m-Cl)-2-PPh3-
m
lographically determined. These clusters exhibit a triangular {M2S}
face with the MeM edge being bridged by either a chlorine or a CO
ligand. In the rhodathiaboranes, 9e11, the RheRh distance
changes from the values of 2.6307(9) and 2.592(1) Å, found for the
The addition of the calculated and measured IR stretching
frequency data of the bridging CO to the plot in Fig. 2 for the
[(PMe2Ph)4M2B10H10] compounds shows that it fits quite well into
an almost linear progression of increasing binding strength of the
CO ligand to the MeM vector in the order Pd2 > PtPd > Pt2 > IrRh 8.
However, the increased binding strength is such that the CO ligand
is now irreversibly bound. In contrast to the Pt/Pd compounds,
which show reversible loss of the CO ligand by heating or by
photolysis [57], no such activity is apparent for 8. Additionally, the
decarbonylating agent Me3NO, which, for example, affords quan-
titatively decarbonylation of the monometallathiaborane [8,8,8-
(CO)(PMe3)2-8,7-IrSB9H10] 4 [61], is inactive here. However, since
the binding of small molecules across the MM0 vector in the 12-
vertex metallaboranes is tunable [55,62,63], a systematic modifi-
cation of the metal centres in bimetallic {MM0SB9} systems could
similarly induce reversibility. There is potential here for these B-
frame bimetallics to become catalyst precursors in the activation of
small molecules.
3. Conclusion
ꢀ
The treatment of the 9-vertex anion [arachno-4-SB8H11
]
with [MCl(CO)(PPh3)2], where M ¼ Rh or Ir, is shown to be
a convenient synthetic route for the formation of new 10-vertex
arachnoemetallathiaboranes [9,9,9,9-(CO)(H)(PPh3)2-arachno-9,6-
MSB8H10
[arachno-6-SB9H12
]
in good yields. Alternatively, the 10-vertex anion
ꢀ
]
allows the formation of the 10-vertex
iridathiaborane analogue, [9,9,9,9-(CO)(H)(PMe3)2-arachno-9,6-
IrSB8H10] (5), via cluster dismantling. The irida- and rhodathiade-
caboranes are the first Group 9 metallathiaboranes based on the
Fig. 3. Molecular structure of 8. Only the ipso-carbons for the phenyl rings are shown
for clarity. Selected bond lengths (Å) and interatomic angles (ꢁ): Ir(1)eRh(2) 2.7583(4),
Ir(1)eP(1) 2.3262(10), Ir(1)eP(2) 2.2752(10), Rh(2)eP(3) 2.3533(11), Rh(2)eP(4)
2.2723(10), Ir(1)eS(3) 2.4422(9), Rh(2)eS(3) 2.4434(9), Ir(1)eC(1) 2.040(4), Rh(2)e
C(1) 2.097(3), C(1)eO 1.172(5), P(1)eIr(1)eP(2) 93.16(4), P(3)eRh(2)eP(4) 94.30(4),
Ir(1)eC(1)eRh(2) 83.60(14), P(1)eIr(1)eRh(2) 119.45(3), P(2)eIr(1)eRh(2) 128.42(3),
P(3)eRh(2)eIr(1) 118.97(3), P(4)eRh(2)eIr(1) 131.29(2), Ir(1)eC(1)eO 139.0(3),
Rh(2)eC(1)eO 137.4(3).
{h
3-SB8H10
diffraction.
The preparation of [1,2-(
1,2-IrRhSB9H9] demonstrates that deprotonation of
} moiety that have been characterized by X-ray
m
-CO)-1,1,2-(PMe3)3-2-(PPh3)-closo-
8
[(PPh3)2RhSB9H10] 1 with strong bases and subsequent treatment
with transition element complexes open the door to the

28
S. Luaces et al. / Journal of Organometallic Chemistry 721-722 (2012) 23e30
synthesis of bimetallic 12-vertex clusters. Although the yield
of 8 is low, the route could, in principle, be improved or it
could work better with other metal complexes. Given the inter-
4.3. Synthesis of [9,9,9,9-(CO)(H)(PPh3)2-arachno-9,6-RhSB8H10] (6)
60.0 mg (0.47 mmol) of arachno-4-SB8H12, placed in a Schlenk
tube, was dissolved in 10 mL of dry Et2O under an atmosphere of
argon. The tube, closed with a rubber septum, was immersed in
liquid nitrogen, and an equimolar amount of MeLi (1.6 M in Et2O)
was injected with a syringe (through the septum). The resulting
milky suspension was stirred for 5 min. Then, 325 mg (0.47 mmol)
of [RhCl(CO)(PPh3)2] was added and the reaction mixture was
stirred at room temperature under an atmosphere of argon. After
the first hour, there was formation of a beige precipitate; but the
stirring was maintained for another 4 h. The resulting suspension
was filtered through a frit, the solid washed with pentane, and
dried under vacuum for 8 h. The product was finally crystallized
from CH2Cl2/hexane to give 230 mg of 6 (62%). 11B and 1H NMR data
are gathered in Table 1, and additional spectroscopic data are re-
ported here: IR(ATR): nmax/cmꢀ1 2554e2502 s (BH), 2030 s (RhCO),
2010 m (RhCO). 1He{11B} NMR (300 MHz; CD2Cl2; 298 K):
esting reactivity found in [(PMe2Ph)4MM0B10H10
]
(where
MM0 ¼ PtPt, PtPd, PdPd) [57,62,63], the assembly of two metal
centres on the {SB9H9} scaffold could generate systems with
a reactivity that may complement the reversible binding of small
molecules observed in 12-vertex bimetallic platina- and
palladaboranes.
4. Experimental
4.1. General procedures
Reactions were carried out under an argon atmosphere using
standard Schlenk line techniques. Solvents were obtained dried
from a Solvent Purification System of Innovative Technnology Inc.
The thiaborane reagents, arachno-4-SB8H12 and Cs[arachno-6-
SB9H12] [27,28], and the metal complexes [RhCl(CO)(PPh3)2] [64],
[IrCl(CO)(PPh3)2] [65], and [IrCl(CO)(PMe3)2] [66] were prepared
according to the literature methods. Proton Sponge was purchased
from Aldrich and used as received. Preparative thin-layer chro-
matography (TLC) was carried out using 1 mm layers of silca gel G
(Fluka, type GF254) made from water slurries on glass plates of
dimensions 20 ꢂ 20 cm and dried in air at 25 ꢁC. Infrared spectra
were recorded on a PerkineElmer Spectrum 100 spectrometer,
using a Universal ATR Sampling Accessory. NMR spectra were
recorded on Bruker Avance 300 MHz and AV 400 MHz spec-
trometers, using 11B, 11Be{1H}, 1H, 1He{11B} and 1He
d
7.45e6.97 (30H, aromatic, 2PPh3). 31Pe{1H} NMR (161 MHz;
1
2
CDCl3; 223 K):
d
13.5 (dd, JRheP ¼ 75 Hz, JPP ¼ 24 Hz; major
1 2
component), 28.4 (dd, JRheP ¼ 108 Hz, JPeP ¼ 24 Hz; major
1
component), 35.3 (d, JRheP ¼ 107 Hz; minor component). m/z
(MALDI) 492 [M ꢀ (CO) ꢀ (PPh3) ꢀ 3H]þ; isotope envelope.
C37H41B8O1P2Rh1S1 requires 785].
4.4. Synthesis of [9,9,9,9-(CO)(H)(PPh3)2-arachno-9,6-IrSB8H10] (7)
Following the procedure above for the synthesis of 6, 205 mg
(61%) of the CO-ligated iridathiaborane analogue, 7, was isolated.
11B and 1H NMR data are gathered in Table 2, and additional
spectroscopic data are reported here: IR(ATR): nmax/cmꢀ1
2554e2501 s (BH), 2114 m (IrH), 2014 s (IrCO). 1He{11B} NMR
{
11B(selective)} techniques. 1H NMR chemical shifts were
measured relative to partially deuterated solvent peaks but are
reported in ppm relative to tetramethylsilane. 11B chemical shifts
are quoted relative to [BF3(OEt)2)] and 31P chemical shifts are
quoted relative to 85% aqueous H3PO4. Mass spectrometric data
were recorded on a MICROFLEX instrument operating in either
positive or negative modes, using matrix-assisted laser desorp-
tion/ionization (MALDI). A nitrogen laser of 337 nm (photon
energy of 3.68 eV) was used for the ionization processes, and the
molecules under study were protected with a matrix of trans-2-[3-
(4-tert-butylphenyl)-2-methyl-2-propenylidene]malononitrile
(DCTB).
(300 MHz; CD2Cl2; 298 K):
d
7.72e6.95 (30H, aromatic, 2PPh3). 31Pe
{1H} NMR (161 MHz; CDCl3; 295 K):
d
1.0 [d, 2J(31P ꢀ 31P) ¼ 18 Hz,
major component], ꢀ16.6 [d, 2J(31P ꢀ 31P) ¼ 17 Hz, major compo-
nent], 6.4 (s, minor component); m/z (MALDI) 871 [M ꢀ 3H]þ; 842
[M ꢀ (CO) ꢀ 4H]þ; isotope envelope. C37H41B8O1P2Ir1S1 requires
874].
4.5. Synthesis of [1,1,2-(PMe3)3-2-(PPh3)-1,2-(m-CO)-closo-1,2-
IrRhSB9H9] (8)
A two-neck round bottom flask containing [(PPh3)2RhSB9H10
]
(1; 94.6 mg, 123 mol) was attached to the Schlenk line, evacuated
m
4.2. Synthesis of [9,9,9,9-(CO)(H)(PMe3)2-arachno-9,6-IrSB8H10] (5)
and refilled with argon and then 10 ml THF injected through
a septum. The solution was cooled to ꢀ70 ꢁC and 0.08 ml of 1.6 M
nBuLi was added by syringe. The solution was allowed to warm to
ambient temperature with stirring then [IrCl(CO)(PMe3)2] (50 mg,
0.127 mmol) was added against a flow of argon and the stirring
continued overnight after which time it was filtered in air, applied
to preparative TLC plates and developed in 70:30 CH2Cl2/hexane
giving one orange coloured band, RF 0.7. The band was washed from
the silica gel with CH2Cl2 and crystallized by diffusion of hexane
into a CH2Cl2 solution of the compound affording very small dark
Compound 5 was prepared according to the reaction described
previously for the preparation of [8,8,8-(CO)(PMe3)2-nido-8,7-
IrSB9H10] (4) from the reaction of CsSB9H12 and [IrCl(CO)(PMe3)2]
in THF solution [59]. In the original preparation, TLC (GF254 silica
gel) plating of the reaction mixture in CH2Cl2/hexane, 80:20 affor-
ded two bands: a pale yellow band RF 0.4 identified as 4 (71%) and
a colourless UV active band, RF 0.7, which was not identified at that
time. Subsequent work has now identified the UV active band as 5.
0.392 g (0.14 mmol) of CsSB9H12 and 0.573 g (0.14 mmol) of
redeorange plates of the title compound 8, 7.7 mg, 8.1
mmol, 0.65%.
[IrCl(CO)(PMe3)2] affords 0.047 g (0.0094 mmol) of 5 (6.7%).
d
(
11B)
IR(ATR): nmax/cmꢀ1
n
C ¼ O 1760;
n
BeH 2503. m/z (exact mass
[
d
(1H) in brackets] (CDCl3, 298 K) 1BH þ 23.6[þ4.78, J 32.1 Hz],
spectra were collected on a JEOL JMS700 mass spectrometer in the
FAB mode with an NBA matrix together with ca. 0.1 mmol of CsI co-
solute): C28H51B7O1P4S1Rh1Ir1Cs, [M þ Cs]þ, meas. 1085.1259, calc.
1085.1268.
1BH þ 10.5[þ5.03], 2BH þ 8.1[þ2.81],1BH ꢀ29.1[þ0.61],1BH ꢀ29.8
[þ1.01], ꢀ31.5[þ1.59], ꢀ33.2[þ1.46]. 1H NMR (300 MHz; CDCl3;
298 K):
d
IreH-13.69 [dd, J(103
P
ꢀ
1H)
¼
141 Hz,
2J(31P ꢀ 1H) ¼ 22 Hz], þ1.90 [d, 2J(31P ꢀ 1H) ¼ 9 Hz, PMe3], þ1.52 [d,
2J(31P ꢀ 1H) ¼ 9 Hz, PMe3]. 31Pe{1H} NMR (161 MHz; CDCl3; 223 K):
The 11Be{1H} NMR spectrum showed
a mixed envelope
between þ5 and ꢀ10 ppm comprising sharp and underlying broad
resonances with a total integrated intensity of 8 boron atoms plus
one sharp resonance at higher field. Of these, the following may be
d
ꢀ53.8 [ d, 2J(31P ꢀ 31P) ¼ 20 Hz, P(2)], ꢀ47.9 [broad, P(1)]. Analysis
Found (Calc.): C 16.72(16.75), H 5.85(5.82). IR(ATR): nmax/cmꢀ1
2554e2501 s (BH), (IrH), 2014 s (IrCO).
individually identified: d( d
11B) [ (1H) in brackets] (CD2Cl2, 293 K),

S. Luaces et al. / Journal of Organometallic Chemistry 721-722 (2012) 23e30
29
2BH þ 5.6 [þ5.30, þ0.07], 1BH þ 2.9 [þ3.22], 1BH ꢀ0.4 [þ3.98],
1BH ꢀ2.0 [þ3.00], 3BH ꢀ10.4 [þ2.48] together with 1BH ꢀ37.0
optimized geometries, and computed 11B shielding values were
related to chemical shifts by comparison with the computed value
[þ1.47]. 1He{11B} NMR (300 MHz; CD2Cl2; 298 K):
d
7.3 to 7.9
for B2H6, which was taken to be
d(
11B) þ 16.6 ppm relative to the
(aromatic region), þ1.58 [d, 2J(31Pe1H) ¼ 9 Hz, IrePMe3], þ1.50 [d,
BF3(OEt2) ¼ 0.0 ppm standard. Computed carbonyl frequencies are
2J(31Pe1H) ¼ 10 Hz, IrePMe3], þ0.90 [d, 2J(31Pe1H) ¼ 9 Hz,
given with a 0.9613 scaling factor [72].
RhePMe3]. 31Pe{1H} NMR (161 MHz; CDCl3; 243 K):
d
þ43.6 [d,
2
1J(103Rhe31P) ¼ 189 Hz, J(31P(4)e31P(3)) ¼ 44 Hz, P(4)Ph3], ꢀ28.1
Acknowledgements
[d, P(3)Me3], ꢀ27.7 [d,
J
2 31P(1)e31P(2)) ¼ 25 Hz, PMe3], ꢀ45.0 [d,
2J(31P(1)e31P(2)) ¼ 25 Hz, PMe3].
We acknowledge the Spanish Ministry of Science and Innova-
tion (CTQ2009-10132, CONSOLIDER INGENIO, CSD2009-00050,
MULTICAT and CSD2006-0015, Crystallization Factory) and the
Grant Agency of the Czech Republic (grant no. P207/11/1577) for
support of this work. J.B. thanks the Spanish Ministry of Science
Innovation for sabbatical funding (SAB2009-0191) and S.L. thanks
the “ Ministerio de Ciencia y Tecnología” for a pre-doctoral
scholarship.
4.6. X-ray crystallography
X-ray diffraction data were collected at low temperature
(100(2) K) on an automatic Bruker Kappa APEX DUO CCD area
detector diffractometer equipped with graphite-monochromated
MoKa
radiation (
l
¼ 0.71073 Å) using narrow frames (0.3ꢁ in
u)
for 6; and on a the BM16 CRG beamline at the ESRF in the case of 5
and 8. In all cases, single crystals were mounted on micro-mount
supports and were covered with a protective perfluoropolyether.
The structures were solved and refined using the programmes
SADABS and SHELXL-97 respectively [67,68]. The programs ORTEP-
3 [69] and PLATON [70] were used to prepare Figs. 1and 3. Collec-
tion and refinement data are shown in Table 3.
Appendix A. Supplementary material
Supplementary material associated with this article can
be found, in the online version, at doi:10.1016/j.jorganchem.2012.
04.003.
References
4.7. Calculations
[1] M.A. Fox, Polyhedral Carboranes, in: R.H. Crabtree, D.M.P. Mingos (Eds.),
Comprehensive Organometallic Chemistry III, Elsevier Ltd., Oxford, 2007, pp.
49e112.
[2] T. Onak, Polyhedral Organoboranes, in: G. Wilkinson, F.G.A. Stone, E.W. Abel
(Eds.), Comprehensive Organometallic Chemistry, Pergamon Press, Ltd.,
Oxford, 1982, pp. 411e457.
[3] T. Onak, Polyhedral Carboranes, in: E.W. Abel, F.G.A. Stone, G. Wilkinson
(Eds.), Comprehensive Organometallic Chemistry, Elsevier Science Ltd.,
Oxford, 1995, pp. 217e255.
[4] R.N. Grimes, Metallacarboranes and Metallaboranes, in: G. Wilkinson,
F.G.A. Stone, E.W. Abel (Eds.), Comprehensive Organometallic Chemistry,
Pergamon Press Ltd., Oxford, 1982, pp. 459e542.
All calculations were performed using the Gaussian 03 package
[71]. Structures were initially optimized using standard methods
with the STO-3G* basis-sets for C, B, P, S, and H with the LANL2DZ
basis-set for the metal atom. The final optimizations, including
frequency analyses to confirm the true minima, together with GIAO
nuclear-shielding calculations, were performed using B3LYP
methodology, with the 6-31G* and LANL2DZ basis-sets. The GIAO
nuclear shielding calculations were performed on the final
[5] R.N. Grimes, Transition Metal Metallacarboranes, in: E.W. Abel, F.G.A. Stone,
G. Wilkinson (Eds.), Comprehensive Organometallic Chemistry II, Pergamon,
Oxford, 1995, pp. 373e430.
Table 3
[6] N.S. Hosmane, J.A. Maguire, Metallacarboranes of d- and f-Block Metals, in:
R.H. Crabtree, D.M.P. Mingos (Eds.), Comprehensive Organometallic Chem-
istry, Elsevier, Oxford, 2007, pp. 175e264.
[7] Z. Xie, Coord. Chem. Rev. 231 (2002) 23e46.
[8] Z. Xie, Acct. Chem. Res. 36 (2003) 1e9.
[9] Z. Qiu, S. Ren, Z. Xie, Acct. Chem. Res. 44 (2011) 299e309.
[10] J. Zhang, Z. Xie, Chem.-Asian J. 5 (2010) 1742e1757.
[11] R. Satapathy, B.P. Dash, J.A. Maguire, N.S. Hosmane, Collect. Czech. Chem.
Commun. 75 (2010) 995e1022.
Crystallographic and structure refinement data.
Compound
Chemical formula
Formula mass
Crystal system
a/Å
5
6
8
C7H29B8IrOP2S C37H41B8OP2RhS C28H51B9IrOP4RhS
501.98
785.09
952.06
Monoclinic
12.8736(10)
16.7758(13)
26.890(2)
90.00
96.4460(10)
90.00
5770.7(8)
100(2)
Monoclinic
11.0766(5)
21.6858(11)
15.3462(8)
90.00
93.0830(10)
90.00
3680.9(3)
100(2)
Monoclinic
12.1060(10)
25.7300(10)
12.3430(10)
90.00
95.659(2)
90.00
3826.0(5)
100(2)
P21/n
4
Synchrotron
4.391
b/Å
c/Å
[12] X.-L. Meng, Ziran Kexueban 36 (2010) 101e104.
ꢁ
ꢁ
ꢁ
/
a
/
[13] A.R. Kudinov, D.A. Loginov, Russ. Chem. Bull. 58 (2010) 600e603.
[14] W. Kaim, N.S. Hosmane, J. Chem. Sci. 122 (2010) 7e18 (Bangalore, India).
[15] N.S. Hosmane, Y. Zhu, J.A. Maguire, W. Kaim, M. Takagaki, J. Organomet. Chem.
694 (2009) 1690e1697.
b
/
g
Unit cell volume/Å3
Temperature/K
Space group
Z
[16] P.A. Jelliss, Inorg. Chem. 29 (2008) 1e25.
P21/c
12
Cc
4
[17] L.T. Todd, Heterocarboranes, in: G. Wilkinson, F.G.A. Stone, E.W. Abel (Eds.),
Comprehensive Organometallic Chemistry, Pergamon Press Ltd., Oxford,
1982, pp. 534e553.
Radiation type
MoKa
MoK
a
Absorption coefficient, 7.202
m
0.639
21,879
8584
[18] S. Hermánek, Chem. Rev. 92 (1992) 325.
/mmꢀ1
[19] L.T. Todd, Main-Group Heteroboranes, in: E.W. Abel, F.G.A. Stone,
G. Wilkinson (Eds.), Comprehensive Organometallic Chemistry II, Elsevier
Science, Oxford, 1995, pp. 257e273.
[20] L. Wesemann, s- p-Block Heteroboranes and Carboranes, in: D.M.P. Mingos,
R.H. Crabtree (Eds.), Comprehensive Organometallic Chemistry, Elsevier,
Oxford, 2007, pp. 113e131.
No. of reflections
measured
No. of independent
reflections
40,161
13259
53,605
8503
Rint
0.0499
0.0363
0.0172
0.0204
0.0795
0.0433
[21] S. Kupper, P.J. Carroll, L.G. Sneddon, J. Am. Chem. Soc. 114 (1992) 4914e4915.
[22] S.O. Kang, L.G. Sneddon, Inorg. Chem. 27 (1988) 3769e3772.
[23] K.J. Donaghy, P.J. Carroll, L.G. Sneddon, Inorg. Chem. 36 (1997) 547e553.
[24] T. Jelinek, C.A. Kilner, S.A. Barrett, M. Thornton-Pett, J.D. Kennedy, Chem.
Commun. (1999) 1905e1906.
Final R1 values
(I > 2
Final wR(F2) values
(I > 2 (I))
s(I))
0.0758
0.0698
0.0841
0.935
0.0532
0.0207
0.0535
1.029
0.1237
0.0446
0.1256
1.098
s
ꢀ
Final R1 values
(all data)
[25] T. Jelinek, J.D. Kennedy, B. Stíbr, M. Thorntonpett, Angew. Chem. Int. Ed. 33
(1994) 1599e1601.
Final wR(F2) values
(all data)
[26] M. Bown, X.L.R. Fontaine, N.N. Greenwood, J.D. Kennedy, Z. Anorg, Allg. Chem.
602 (1991) 17e29.
[27] R.W. Rudolph, W.R. Pretzer, Inorg. Synth. 22 (1983) 226e231.
Goodness of fit
on F2
ꢀ
[28] K. Base, M.G.H. Wallbridge, X.L.R. Fontaine, N.N. Greenwood, J.H. Jones,
ꢀ
J.D. Kennedy, B. Stíbr, Polyhedron 8 (1989) 2089e2090.

30
S. Luaces et al. / Journal of Organometallic Chemistry 721-722 (2012) 23e30
[29] B. Calvo, M. Kess, R. Macias, C. Cunchillos, F.J. Lahoz, J.D. Kennedy, L.A. Oro,
Dalton. Trans. 40 (2011) 6555e6564.
[48] Y.-H. Kim, A. Brownless, P.A. Cooke, J.D. Kennedy, M. Thornton-Pett, Inorg.
Chem. Commun. 1 (1998) 19e22.
[30] A. Alvarez, R. Macias, M.J. Fabra, F.J. Lahoz, L.A. Oro, J. Am. Chem. Soc. 130
(2008) 2148e2149.
[49] T.K. Hilty, D.A. Thompson, W.M. Butler, R.W. Rudolph, Inorg. Chem. 18 (1979)
2642e2651.
[31] A. Alvarez, R. Macias, J. Bould, M.J. Fabra, F.J. Lahoz, L.A. Oro, J. Am. Chem. Soc.
130 (2008) 11455e11466.
[32] A. Alvarez, R. Macias, J. Bould, C. Cunchillos, F.J. Lahoz, L.A. Oro, Chem. Eur. J.
15 (2009) 5428e5431.
[33] J.I. van der Vlugt, J.N. Reek, Angew. Chem. Int. 48 (2009) 8832e8846.
[34] B. Calvo, R. Macías, C. Cunchillos, F.J. Lahoz, L.A. Oro, Organometallics (2012)
doi:10.1021/om200707m.
[50] K. Wade, Adv. Inorg. Chem. Radiochem. 18 (1976) 1e66.
[51] R.E. Williams, Adv. Inorg. Chem. Radiochem. 18 (1976) 67e142.
[52] D.E. Hyatt, F.R. Scholer, L.J. Todd, Inorg. Chem. 6 (1967) 630e631.
[53] W.N. Lipscomb, R.J. Wiersema, M.F. Hawthorne, Inorg. Chem. 11 (1972)
651e652.
[54] R.R. Rietz, A.R. Siedle, R.O. Schaeffer, L.J. Todd, Inorg. Chem. 12 (1973)
2100e2102.
[35] C. Elschenbroich, Organometallics, Wiley-VCH, Weinheim, 2006.
[36] T.P. Fehlner (Ed.), Inorganometallic Chemistry, Plenum Press, New York, 1992.
[37] G.D. Friesen, A. Barriola, P. Daluga, P. Ragatz, J.C. Huffman, L.J. Todd, Inorg.
Chem. 19 (1980) 458.
[55] M. Bown, X.L.R. Fontaine, J.D. Kennedy, J. Chem. Soc. Dalton Trans. (1988)
1467e1473.
[56] R. Macías, J. Bould, J. Holub, J.D. Kennedy, B. Stíbr, M. Thornton-Pett, Dalton.
ꢀ
Trans. (2007) 2885e2897.
[38] G. Ferguson, M.F. Hawthorne, B.A. Kaitner, F.J. Lalor, Acta Cryst. C40 (1984)
1707.
[39] K. Nestor, X.L.R. Fontaine, N.N. Greenwood, J.D. Kennedy, M. Thornton-Pett,
J. Chem. Soc. Dalton Trans. 2657 (1991) 2667.
[40] K.J. Adams, T.D. McGrath, R.L. Thomas, A.S. Weller, A.J. Welch, J. Organomet.
Chem. 527 (1997) 283e285.
[41] K.J. Adams, T.D. McGrath, G.M. Rosair, A.S. Weller, A.J. Welch, J. Organomet.
Chem. 550 (1998) 315e329.
[57] J. Bould, T. Base, M.G.S. Londesborough, L.A. Oro, R. Macias, J.D. Kennedy,
P. Kubat, M. Fuciman, T. Polivka, K. Lang, Inorg. Chem. 50 (2011) 7511e7523.
[58] S.O. Kang, P.J. Carroll, L.G. Sneddon, Inorg. Chem. 28 (1989) 961.
[59] K.J. Adams, T.D. McGrath, A.J. Welch, Polyhedron 17 (1998) 341e349.
[60] O. Volkov, N.P. Rath, L. Barton, Organometallics 22 (2003) 2548e2550.
[61] J. Bould, C. Cunchillos, F.J. Lahoz, L.A. Oro, J.D. Kennedy, R. Macias, Inorg. Chem.
49 (2010) 7353e7361.
[62] J. Bould, J.D. Kennedy, Chem. Commun. (2008) 2447e2449.
[63] J. Bould, C.A. Kilner, J.D. Kennedy, Dalton Trans. (2005) 1574e1582.
[64] D. Evans, J.A. Osborn, G. Wilkinson, Inorg. Synth. 11 (1968) 99e101.
[65] K. Vrieze, J.P. Collman, C.T. Sears Jr., M. Kubota, Inorg. Synth. 11 (1968)
101e104.
[42] G. Ferguson, M.C. Jennings, A.J. Lough, S. Coughlan, T.R. Spalding, J.D. Kennedy,
ꢀ
X.L.R. Fontaine, B. Stíbr, J. Chem. Soc. Chem. Commun. (1990) 891e894.
[43] S. Coughlan, T.R. Spalding, G. Ferguson, J.F. Gallagher, A.J. Lough,
ꢀ
X.L.R. Fontaine, J.D. Kennedy, B. Stíbr, J. Chem. Soc. Dalton Trans. (1992)
2865e2871.
[66] J.A. Labinger, J.A. Osborn, Inorg. Synth. 18 (1983) 62e65.
[67] G.M. Sheldrick, SADABS Program for Correction of Area Detector Data, Uni-
verisity of Göttingen, Göttingen, Germany, 1999.
[44] J. Bould, W. Clegg, S.J. Teat, L. Barton, N.P. Rath, M. Thornton-Pett,
J.D. Kennedy, Inorg. Chim. Acta 289 (1999) 95e124.
[45] J. Bould, P. Brint, J.D. Kennedy, M. Thornton-Pett, L. Barton, N.P. Rath, Collect.
Czech. Chem. Commun. 62 (1997) 1239e1253.
[68] G.M. Sheldrick, SHELXL-97, University of Göttingen, Göttingen, Germany,
1997.
[46] J. Bould, M. Bown, R.J. Coldicott, E.J. Ditzel, N.N. Greenwood, I. Macpherson,
P. MacKinnon, M. Thornton-Pett, J.D. Kennedy, J. Organomet. Chem. 690
(2005) 2701e2720.
[47] M.G.S. Londesborough, C. O’Dowd, J. Bould, S.A. Barrett, C.A. Kilner,
M. Thornton-Pett, J.D. Kennedy, J. Chem. Cryst. 30 (2000) 283e289.
[69] L.J. Farrugia, J. Appl. Cryst. 32 (1999) 837e838.
[70] A.L. Spek, J. Appl. Cryst. 36 (2003) 7e13.
[71] M.J. Frisch, J.A. Pople, et al., GAUSSIAN 03, Gaussian, Inc., Wallingford, CT,
2004, (Rev. C.02).
[72] J.P. Merrick, D. Moran, L. Radom, J. Phys. Chem. A 111 (2007) 11683e11700.
́