Coordination chemistry of thioether-carboranes in polynuclear metal carbonyl cluster complexes. B-H activation of thioether-carboranes by dirhenium carbonyl complexes

Article abstract of DOI:10.1016/j.jorganchem.2017.09.004

Two new dirhenium compounds Re₂(CO)₈[μ-η²-1,3-C₂B₁₀H₁₀(1-SCH₃)](μ-H), 1 (3.2 % yield) and Re₂(CO)₈[μ-η²-1,4-C₂B₁₀H₁₀(1-SCH₃)](μ-H), 2 (31 % yield) were obtained from the reaction of closo-o-(1-SCH₃)C₂B₁₀H₁₁ with Re₂(CO)₈[μ-η²-C(H)C(H)Buⁿ](μ-H) in an octane solution heated to reflux. Both compounds contain a C₂B₁₀H₁₀(1-SCH₃) ligand that bridges the pair of rhenium atoms by the sulfur atom and one of the boron atoms of the carborane cage. The Re – B bonds were formed by oxidative addition of one of the B – H bonds of the carborane to one of the Re atoms. The isomers differ by which boron atom, B(3) for 1 and B(4) for 2, has been added to the Re atom. Compound 1 was isomerized to 2 by heating to 107 °C, but 2 does not isomerize back to 1. A mechanism for the isomerization that involves a reductive-elimination of B(3) and the hydride ligand of 1 followed by an oxidative-addition of the neighboring B(4)-H bond to form 2 is proposed. The new compound Re₂(CO)₇[μ-η³-C₂B₁₀H₉(1,2-(SCH₃)₂](μ-H), 3 was obtained in 38% yield from the reaction of [o-1,2-(SCH₃)₂]C₂B₁₀H₁₀ with Re₂(CO)₈[μ-η²-C(H)C(H)Buⁿ](μ-H) in an octane solution heated to reflux for 2h. The bridging C₂B₁₀H₉(1,2-(SCH₃)₂ ligand is coordinated to one of the rhenium atoms by the two sulfur atoms at one of the Re atoms and the carborane boron atom B(3) also underwent cleavage at the B(3) – H bond to form the Re – B(3) bond to the other Re atom.

Full text of DOI:10.1016/j.jorganchem.2017.09.004

Journal of Organometallic Chemistry xxx (2017) 1e6
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Coordination chemistry of thioether-carboranes in polynuclear metal
carbonyl cluster complexes. B-H activation of thioether-carboranes by
dirhenium carbonyl complexes
*
Richard D. Adams , Joseph Kiprotich
Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 25 July 2017
Received in revised form
2
8 3
Two new dirhenium compounds Re (CO) [m- m-H), 1 (3.2 % yield) and
h2-1,3-C2B10H10(1-SCH )](
2
Re
SCH
compounds contain a C
2
(CO)
8
[
m
-
H
h
-1,4-C
2 10 3
B H10(1-SCH )](m-H), 2 (31 % yield) were obtained from the reaction of closo-o-(1-
2
n
3
)C
2
B
10
11 with Re
2
(CO)
8
[
m
-
h
-C(H)C(H)Bu ](
m-H) in an octane solution heated to reflux. Both
30 August 2017
2
B
10
H
10(1-SCH
3
) ligand that bridges the pair of rhenium atoms by the sulfur atom
Accepted 2 September 2017
Available online xxx
and one of the boron atoms of the carborane cage. The Re e B bonds were formed by oxidative addition
of one of the B e H bonds of the carborane to one of the Re atoms. The isomers differ by which boron
atom, B(3) for 1 and B(4) for 2, has been added to the Re atom. Compound 1 was isomerized to 2 by
Dedicated to Professor Narayan Hosmane on
the occasion of his 70th birthday.
ꢀ
heating to 107 C, but 2 does not isomerize back to 1. A mechanism for the isomerization that involves a
reductive-elimination of B(3) and the hydride ligand of 1 followed by an oxidative-addition of the
3
Keywords:
Carborane
Rhenium
BH oxidative-addition
Isomerization
Crystal structure
neighboring B(4)-H bond to form 2 is proposed. The new compound Re (CO) [
m
-h
-C2B10H (1,2-
2
7
9
(
h
SCH
-C(H)C(H)Bu ](
3
)
2
](
m
-H), 3 was obtained in 38% yield from the reaction of [o-1,2-(SCH
3
)
2
]C
2
B
10
H
10 with Re
2
(CO)
8
[
m
-
2
n
m
-H) in an octane solution heated to reflux for 2h. The bridging C
2
B
10
H
9
(1,2-(SCH
3
)
2
ligand is coordinated to one of the rhenium atoms by the two sulfur atoms at one of the Re atoms and the
carborane boron atom B(3) also underwent cleavage at the B(3) e H bond to form the Re e B(3) bond to
the other Re atom.
©
2017 Elsevier B.V. All rights reserved.
1. Introduction
2 10 8 3 3 9 2
6,10,11-C B H S(CH )]Os (CO) (m-H) , B, see Scheme 1.
To follow up on our studies of these interesting new cage
opening reactions of the closo-carboranes, we have now investi-
Polyhedral carborane cage compounds have now been studied
extensively for over 50 years [1]. In recent years, transition metal
carborane complexes and metallacarboranes have attracted
considerable interest [2]. The addition of heteroatomic groupings to
the carbon atoms in the carborane cage has provided new oppor-
tunities for studies of their coordination chemistry and associated
reactivity [3]. We have recently found that triosmium carbonyl
gated reactions of closo-o-(1-SCH
(SCH ]C 10 with the dirhenium complex Re
-H) [6]. We have obtained two isomers of the dirhenium
3 2 10
)C B H11 and closo-[o-1,2-
2
3
)
2
2
B
m
10
H
2
(CO)
-H),
8
[m-h -C(H)
n
C(H)Bu ](
complex
2
Re
-1,4-C
2
(CO)
8
[
m
-
h
-1,3-C
2
B
10
H
10(1-SCH
)]( -H), 2 from the reaction of
(CO)
3
)](m
1
and
2
Re
closo-o-(1-SCH
and one product Re
the reaction of [o-1,2-(SCH
C(H)Bun]( -H). The results of our studies of the synthesis, charac-
2
(CO)
8
[
m-h
2
B
10
H10(1-SCH
3
m
2
n
3
)C
2
B
10
H
11 with Re
2
8
[m-
h
-C(H)C(H)Bu ](
(1,2-SCH ]( -H), 3 from
10 with Re (CO)
m
-H)
3
cluster complexes can be added to the surface of closo-o-C
2
B
H
10 12
2
(CO)
7
[
m-h
-C
2
B
10
H
9
3 2
) m
2
[
4] and closo-o-(1-SCH )C 11 [5], and when two triosmium
3
2
B
10
H
3
)
2
]C
2
B
10
H
2
8
[m-h -C(H)
clusters are added to the surface of the same cage, some of the B e C
and B e B bonds in the cage can be cleaved leading to opening of the
m
terization and reactivity of these new carborane complexes are
reported herein.
cages. For example, the addition of an Os
3
cluster to the complex
3
Os
3
(CO)
9
[
m
3
-h
-C
2
B
10
H
9
(SCH
3
)](m
-H)
2
, A which leads to an opening
3
3
of cage resulting in the product Os
3
(CO)
9
(
m
-H)[(m
3
-h
-1,4,5-m
3
-h
-
2. Experimental section
2.1. General data
*
Corresponding author.
E-mail address: Adamsrd@mailbox.sc.edu (R.D. Adams).
All reactions were performed under a nitrogen atmosphere by
http://dx.doi.org/10.1016/j.jorganchem.2017.09.004
022-328X/© 2017 Elsevier B.V. All rights reserved.
0
Please cite this article in press as: R.D. Adams, J. Kiprotich, Journal of Organometallic Chemistry (2017), http://dx.doi.org/10.1016/
j.jorganchem.2017.09.004

2
R.D. Adams, J. Kiprotich / Journal of Organometallic Chemistry xxx (2017) 1e6
3 2 2 10
Scheme 1. A schematic of the cage opening of the carborane compound closo-[o-1,2-(SCH ) ]C B H10 induced by the addition of two triosmium carbonyl clusters [5].
using standard Schlenk techniques. Reagent grade solvents were
dried by the standard procedures and were freshly distilled prior to
use. Infrared spectra were recorded on a Thermo Fisher Scientific
100 mL round bottomed flask with 30 mL solution of 58.0 mg
2
n
(0.085 mmol) of Re
2
(CO)
8
[m-h
-C(H)C(H)Bu ](
m-H) in octane. The
ꢀ
solution was then heated to reflux (125 C) for 2 h with intermittent
monitoring by IR spectroscopy. The solvent was then removed in
1
Nicolet IS10 FT-IR spectrophotometer. H NMR spectra were
recorded on a Varian Mercury 300 spectrometer operating at
vacuo and the products were separated by TLC on silica by using pure
00.1 MHz 11B NMR spectra were recorded on a Varian Mercury
hexane solvent to yield 16.4 mg of Re
SCH ](
ꢁH), 3, (38%) and 21.3 mg of Re
3: IR
1972(m),1945(m),1931(vw). H NMR (CD
6H, 2CH
(CO)
[
m
-
h
3
-C
B
H
(1,2-
3
3
2
7
2
10
9
00 at 96.28 MHz with reference to BF
3
.OEt
2
. Mass spectrometric
3
)
n
2
m
2
(CO)10. Spectral Data for
CO (cm in hexane): 2088(m), 2049(s), 1999(m), 1987(vs),
ꢁ1
(
MS) measurements performed by a direct-exposure probe using
1
ꢀ
electron impact ionization (EI) were made on a VG 70S instrument.
2
2
Cl , 25 C, TMS)
d
¼ 3.06 (s,
þ
þ
closo-o-(1-SCH
3
)C
2
B
10
H
11 [7], [o-1,2-(SCH
3
)
2
]C
2
B
10
H
10 [8] and
3
), ꢁ15.68 (s, ReH, 1H). EI/MS m/z, 805, M ; 790, M ꢁ CH
3
;
2
n
þ
Re
2
(CO)
8
[
m-h
-C(H)C(H)Bu ](
m-H) [6] were prepared according to
762, M -CO. These ions displayed isotopic distributions consistent
with the presence of two rhenium atoms and ten boron atoms.
previously reported procedures. Product separations were per-
formed by TLC in the open air on Analtech 0.25 or 0.5 mm silica gel
6
0 Å F254 glass plates.
2.5. Crystallographic analyses
2
Re
.2. Synthesis of Re (CO)
2
8
[
m
-
h
2-1,3-C
10(SCH )](
ꢁH), 2
2 10 3
B H10(SCH )](m-H), 1 and
Colorless single crystals of 1 and 2, suitable for X-ray analyses,
were obtained by slow evaporation of solvent from a hexane-
dichloromethane solution at room temperature while crystals of
were obtained by slow evaporation of a hexane solution at room
temperature. Crystals of 2 and 3 were each glued onto the end of a
thin glass fiber. X-ray intensity data were measured by using a
2
2
(CO)
3.0
8
[
m
-
h
-1,4-C
2
B
10
H
3
m
6
m
L (0.331 mmol) of closo-o-(1-SCH
3 2 10
)C B H11 was added to
3
a 100 mL round bottomed flask containing a 30 mL solution of
2
octane solvent. The solution was then heated to reflux (125 C) for
2
2
n
25.0 mg (0.331 mmol) of Re
2
(CO)
8
[m
-h
-C(H)C(H)Bu ](
m
-H) in
ꢀ
Bruker SMART APEX CCD-based diffractometer using Mo K
ation (
¼ 0.71073 Å) [9]. The raw data frames were integrated with
the SAINT program by using a narrow-frame integration algorithm
a
radi-
h with intermittent monitoring by IR spectroscopy. The solvent
l
was then removed in vacuo and the products were isolated by TLC
þ
2
on silica by using pure hexane to yield 5.7 mg of Re
10(1-SCH )]( -H), 1 (3.2% yield), 54.2 mg of Re
10(1-SCH )]( (31% yield), and 71.5 mg of
ꢁH),
(CO)10. Spectral data for 1: IR
2
(CO)
8
[m-h -1,3-
[
10]. Corrections for Lorentz and polarization effects were also
2
C
2
B
10
H
3
m
2
(CO)
8
[
m-
h
-
þ
applied with SAINT . Empirical absorption corrections based on the
multiple measurements of equivalent reflections were applied by
using the program SADABS [9]. X-ray intensity data from a colorless
crystal of 1 were collected at 300(2) K by using a Bruker D8 QUEST
diffractometer equipped with a PHOTON-100 CMOS area detector
1,4-C
2
B
10
H
3
m
2
ꢁ
1
Re
2
2
n
CO (cm in hexane): 2113(m),
1
080(m), 2020(vs), 2002(m), 1984(s) 1967(m), 1957(m). H NMR
ꢀ
(
CD
2
Cl
2
, 25 C)
d
¼ 3.77 (s, CH), 3.06 (s, 3H, CH
3
), ꢁ14.30 (s, ReH,
þ
1
H). EI/MS m/z, 787, M ; the ions displayed isotopic distribution
and an Incoatec Microfocus source (Mo K
a
radiation,
l
¼ 0.71073 Å)
patterns consistent with the presence of two rhenium atoms and
ten boron atoms. Spectral Data for 2: IR
ꢀ
[
11]. The data collection strategy consisted of five 180
u-scans at
ꢁ
1
n
CO (cm in hexane):
ꢀ
different 4 settings and two 360 4-scans, with a scan width per
2
1
118(m), 2097(m), 2027(sh), 2022(vs), 2014(sh) 1994(s), 1971(m),
ꢀ
image of 0.5 . The crystal-to-detector distance was 5.0 cm and each
957(vw). 1H NMR (CD
CH
Cl
, 25 C)
ꢀ
d
¼ 3.77 (s, CH), 3.08 (s, 3H,
2
2
image was measured for 15 s. The average reflection redundancy
was 18.9. The raw area detector data frames were reduced, scaled
and corrected for absorption effects using the SAINT and SADABS
programs [11,12]. All structures were solved by a combination of
direct methods and difference Fourier syntheses, and refined by
1
1
1
3
), ꢁ13.08 (s, ReH, 1H). B { H} NMR (in CDCl
3
):
d
¼ ꢁ8.77 ppm
(
7
2 B), ꢁ7.48 (2 B), ꢁ5.27 (4 B), ꢁ2.41 (1 B), ꢁ1.68 (1 B). EI/MS m/z,
þ
87, M ; the ions displayed isotopic distribution patterns consis-
tent with the presence of two rhenium atoms and ten boron atoms.
2
full-matrix least-squares on F by using the SHELXTL software
2.3. Conversion of 1e2
package [13]. All non-hydrogen atoms were refined with aniso-
tropic thermal parameters. Hydrogen atoms were placed in
geometrically idealized positions and included as standard riding
atoms during the least-squares refinements. Compounds 1, 2, and 3
all crystallized in the monoclinic crystal system. The space group
A pure sample of 1 was dissolved in toluene-d
8
in an NMR tube
ꢀ
and was then heated in an oil bath at 107 C. After 5 h and 20 min at
this temperature, the conversion to 2 was complete (100%). As
expected, it was not possible to convert isomer 2 back to 1 under
similar conditions.
P2 /n was indicated by the systematic absences in the data for
1
1
compounds 1 and 2. The space group P2 /c was indicated by the
systematic absences in the data for compound 3. The space group
assignments were confirmed by the successful solution and
refinement of each of the structures. The bridging hydrido ligands
were refined with Re e H distance constraints of 1.80 Å for each of
2
.4. Synthesis of Re
2
(CO)
7
[
m
-
h
3-C
2
B
10
H
9
(SCH
3
)
2
](
m
-H), 3
2
0.2 mg (0.085 mmol) of [o-1,2-(SCH
3 2
) ]C
2 10
B H10 was added to a
Please cite this article in press as: R.D. Adams, J. Kiprotich, Journal of Organometallic Chemistry (2017), http://dx.doi.org/10.1016/
j.jorganchem.2017.09.004

R.D. Adams, J. Kiprotich / Journal of Organometallic Chemistry xxx (2017) 1e6
3
Table 1
Crystallographic data for compounds 1, 2 and 3.
Compound
1
2
3
Empirical formula
Formula weight
Crystal system
Lattice parameters
a (Å)
Re
786.78
Monoclinic
2
SO
8
C
11
B
10
H
14
Re
786.78
Monoclinic
2
SO
8
C
11
B
10
H
14
2 2 7 11 10 16
Re S O C B H
804.86
Monoclinic
7.2873(3)
14.1786(6)
21.9707(10)
90.00
95.565(1)
90.00
9.4934(6)
14.9150(18)
10.2246(12)
15.9356(19)
90.00
102.332(2)
90.00
b (Å)
c (Å)
27.0139(17)
9.5306(6)
90.00
108.085(1)
90.00
a
b
g
(deg)
(deg)
(deg)
V (Å3)
2259.39(17)
2323.4(3)
2374.1(5)
Space group
Z value
P2
4
1
/n
P2
4
1
/n
P2
4
1
/c
r
m
calc (g/cm3)
2.313
10.834
294(2)
50.06
3798
2.249
10.535
294(2)
50.06
3937
2.252
10.395
294(2)
50.06
3457
) (mm 1
ꢁ
)
(Mo K
a
Temperature (K)
ꢀ
2
Q
max ( )
No. Obs. (I > 2
s
(I))
No. Parameters
298
298
295
Goodness of fit (GOF)
1.271
0.000
0.0232; 0.0542
Multi-scan
0.466/0.295
1.773
1.197
0.001
0.0248; 0.0597
Multi-scan
1.00/0.575
0.925
1.056
0.001
0.0404; 0.1025
Multi-scan
1.00/0.481
2.163
Max. shift in cycle
a
Residuals: R1; wR2
Absorption Correction,
(
Max/min values)
ꢁ
3
Largest peak in Final Diff. Map (e /Å )
a
R1 ¼ Shkl(rrFobsr-rFcalcrr)/ShklrFobsr; wR2 ¼ [Shklw(rFobsr-rFcalcr) /ShklwF2obs]1/2; w ¼ 1/s2(Fobs); GOF ¼ [Shklw(rFobsr-rFcalcr) /(ndata e nvari)]1/2
2
2
.
n
ꢀ
the analyses. Crystal data, data collection parameters and refine-
ment results for each of the analyses are summarized in Table 1.
C(H)C(H)Bu ](
m
-H) in an octane solution at reflux (125 C) for 2 h
2
yielded two new compounds Re
2
(CO)
(CO)
8
[
[
m
-
h
h
-1,3-C
-1,4-C
2
B
B
10
H
H
10(1-
10(1-
2
SCH
SCH
3
)](
)](
m
m
-H), 1 (3.2% yield) and Re
2
8
m-
2
10
3
. Results and discussion
3
ꢁH), 2 (31% yield). Both compounds were formed by the
elimination of 1-hexene from the dirhenium cluster followed by
the coordination the sulfur atom and an accompanying oxidative-
3 2 10 2 8
The reaction of closo-o-(1-SCH )C B H11 with Re (CO) [m- -
h2
3
addition of one of the B e H bonds of the closo-o-(1-SCH )
h2-1,3-
Fig. 2. An ORTEP diagram of the molecular structure of Re
SCH )]( -H), 2 showing 20% thermal ellipsoid probability. Selected interatomic bond
distances (Å) are as follow: Re(1) e Re(2) ¼ 3.2861(3), Re(1) e B(4) ¼ 2.243(5), Re(2) e
S(1) ¼ 2.4801(14), C(1) e C(2) ¼ 1.708(8).
2
8
[
m
-
2 8 2 10
(CO) [m- B H10(1-
h2-1,4-C
Fig. 1. An ORTEP diagram of the molecular structure of Re
10(SCH )]( -H), 1 showing 20% thermal ellipsoid probability. Selected inter-
atomic bond distances (Å) are as follow: Re(1) Re(2) 3.2790(4), Re(1)
B(3) ¼ 2.255(7), Re(2) e S(1) ¼ 2.4791(15), C(1) e C(2) ¼ 1.631(8).
(CO)
C
2
B
10
H
3
m
3
m
e
¼
e
Please cite this article in press as: R.D. Adams, J. Kiprotich, Journal of Organometallic Chemistry (2017), http://dx.doi.org/10.1016/
j.jorganchem.2017.09.004

4
R.D. Adams, J. Kiprotich / Journal of Organometallic Chemistry xxx (2017) 1e6
C
2
B
10
H
11 to the remaining dirhenium octacarbonyl fragment.
d
¼ ꢁ13.08.
Compounds 1 and 2 are isomers. Both products were characterized
by IR and H NMR spectroscopy, mass spec and single-crystal X-ray
As indicated by the structures, it appears that both compounds
1
were formed by the addition of the thioether sulfur atom S(1) to
diffraction analyses.
one rhenium atom and an oxidative-addition of one of the B e H
An ORTEP diagram of the molecular structure 1 is shown in
Fig. 1. Compound 1 contains two mutually-bonded rhenium atoms
3 2 10
bonds of the closo-o-(1-SCH )C B H11 to the other rhenium atom
of the dirhenium complex. The structures would suggest that it was
the B(3) e H that was oxidatively added to form 1 and the B(4) e H
that was oxidatively added to form 2, but the mechanisms of the
processes have not been established. Oxidative addition of the BH
bonds at the B(3) and B(4) sites in closo-o-(1-SCH )C B H11 has
3 2 10
been observed previously [5].
that are bridged by a C
2 10 3
B H10(SCH ) ligand and one hydrido ligand.
The C 10(SCH ) ligand is coordinated to rhenium atom Re(2) by
2
B
10
H
3
the thioether sulfur atom S(1), Re(2) e S(1) ¼ 2.4791(15) Å and to
Re(1) by the boron atom B(3), Re(1) e B(3) ¼ 2.255(7) Å. The Re e
Re bond is significantly longer, Re(1) e Re(2) ¼ 3.2790(4) Å than the
Re e Re bond in Re
2
(CO)10 which is 3.041(1) Å [14]. The bond
In further studies, we found that compound 1 was converted to
ꢀ
lengthening effect can be attributed in part to the presence of the
hydrido ligand H(1) which also bridges the Re e Re bond [15]. As
expected, the resonance of the hydrido ligand is highly shielded at
compound 2 quantitatively by heating to 107 C for 5 h 20 min. This
helps to explain the low yield of 1 in the original reaction. Com-
pound 2 does not convert to 1 under these conditions. This raises a
question as to whether all of the observed 2 was formed via 1 as an
intermediate or whether 2 was formed simultaneously and in a
reaction that completes with the formation of 1. We cannot answer
that question with certainty with the studies at hand. However,
these studies do confirm that 1 does convert to 2. This conversion
may occur intramolecularly via a transient reductive-elimination
involving the formation of a B e H bond between B(3) and H(1)
in 1, see Intermediate C in Scheme 2. In C, the B(3) e H(1) group
would most probably remain coordinated to the rhenium atom
Re(1) via an agnostic-like interaction. There are many examples of
such interactions among the many structurally-characterized car-
borane metal complexes [4,16]. A small rotation of the carborane
cage about the C(1) e S(1) bond in C would allow the formation of a
second closely-related intermediate, D, in which the B(4) e H(4)
d
¼ ꢁ14.30. The location of the carbon atom C(1) in the carborane
cage was determined in part by recognition of the short length of
the C e C bond, C(1) e C(2) ¼ 1.631(8) Å [1c]. Compound 1 contains
eight linear terminal carbonyl ligands distributed as shown in Fig. 1.
An ORTEP diagram of the molecular structure 2 is shown in
Fig. 2. Compound 2 is structurally very similar to 1 with a bridging
2 10 3
by a C B H10(SCH ) ligand and one bridging hydrido ligand, Re(2)
e S(1) ¼ 2.4801(14) Å. The main difference is that the carborane
cage is coordinated to the rhenium atom at the boron B(4) of the
cage, Re(1) e B(4) ¼ 2.243(5) Å. The Re e Re bond length in 2 is
similar to that in 1, Re(1) e Re(2) ¼ 3.2861(3) Å. The bond
lengthening effect can be attributed in part to the presence of the
hydrido ligand H(1) which also bridges the Re e Re bond [15]. The
resonance of the hydrido ligand in 2 is also highly shielded at
Scheme 2. A schematic of the proposed mechanism for the isomerization of compound 1 to 2. The CO ligands are shown only as lines to the Re atoms. Most of the H atoms on the
carborane cage are omitted for clarity.
Please cite this article in press as: R.D. Adams, J. Kiprotich, Journal of Organometallic Chemistry (2017), http://dx.doi.org/10.1016/
j.jorganchem.2017.09.004

R.D. Adams, J. Kiprotich / Journal of Organometallic Chemistry xxx (2017) 1e6
5
n
C(H)Bu ](
m
-H). Compounds 1 and 2 are isomers and compound 1 is
ꢀ
cleanly converted to 2 by heating in solution to 107 C. In both
products the carborane is coordinated to one Re atom by the sulfur
atom and to the second Re atom by a cage boron atom as a result of
an oxidative-addition of one of the BH bonds in the carborane. An
intramolecular isomerization process involving reductive-
elimination and oxidative-addition of B-H bonds in the carborane
cage at one of the rhenium atoms has been proposed for the con-
3 2
version of 1 to 2. The bis-thioether carborane [o-1,2-(SCH ) ]
2
n
C
2
B
10
H
10 reacts with Re -C(H)C(H)Bu ](
new compound Re (CO) (1,2-(SCH
3 2
bridging C (1,2-(SCH ) ligand is coordinated to one of the
2
(CO)
8
[
h
m
-C
-
h
m
-H) to yield the
3
2
7
[
m-
2
B
10
H
9
3 2
) ](m-H), 3. The
2
B
H
10 9
rhenium atoms by the two sulfur atoms and to the carborane boron
atom B(3) which has under an oxidative-addition at the B(3) e H
bond in order to form the Re e B(3) bond at the other Re atom
Re(1). Unfortunately, we were not able to add additional metal
groupings to any of these compounds and no carborane cage-
opening transformations were observed with any of these new
carboranyldirhenium compounds.
Acknowledgement
This research was supported by grant CHE-1464596 from the
National Science Foundation. We wish to thank Dr. Mark Smith for
assistance in performing the X-ray structural analysis of compound
2 7 2 10 9
(CO) [m- B H (1,2-
h3-C
Fig. 3. An ORTEP diagram of the molecular structure of Re
SCH ]( -H), showing 20% thermal ellipsoid probability. Selected interatomic
1.
3
)
2
m
3
bond distances (Å) are as follow: Re(1) e Re(2) ¼ 3.3273(6), Re(1) e B(3) ¼ 2.264(11),
Re(2) e S(1) ¼ 2.461(2), Re(2) e S(2) ¼ 2.474(3), C(1) e C(2) ¼ 1.655(12).
Appendix ASupplementary data
The CIF files for each of the structural analyses are available and
they have also been deposited with the Cambridge Crystallographic
Data Centre, CCDC 1564015-1564017.
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.jorganchem.2017.09.004.
bond replaces the B(3) e H(1) bond to form a new agnostic inter-
action at Re(1). The isomerization to 2 would then be completed by
an oxidative addition of the B(4) e H(4) bond to Re(1).
The reaction of [o-1,2-(SCH
3
)
2
]C
2
B
10
H
10 with Re
2
(CO)
8
[
m
-
h2
-
n
ꢀ
C(H)C(H)Bu ](
yielded only one new product Re
SCH }]( -H), 3 in 38% yield. An ORTEP diagram of the molecular
structure 3 is shown in Fig. 3. Compound 3 contains two mutually-
bonded rhenium atoms that are bridged by a C (SCH ligand
and one hydrido ligand. The C (SCH ligand is coordinated
m-H) in an octane solution at reflux (125 C) for 2 h
3
2
7 2 10 9
(CO) [m-h -C B H {1,2-
References
(
3
)
2
m
[1] (a) R.N. Grimes, Carboranes, second ed., Elsevier, Amsterdam, 2011;
2
B
10
H
9
3
)
2
(b) R.N. Grimes, Dalton Trans. 44 (2015) 5939e5956;
(c) V.I. Bregadze, Chem. Rev. 92 (1992) 209e223.
2
B
10
H
9
3 2
)
[2] (a) R.N. Grimes, Carboranes, second ed., vol. 13, Elsevier, Amsterdam, 2011,
pp. 773e1014. Ch;
to rhenium atom Re(2) by both of the thioether sulfur atoms, Re(2)
e S(1) ¼ 2.461(2) Å and Re(2) e S(2) ¼ 2.474(3) Å, and to Re(1) by
the boron atom B(3), Re(1) e B(3) ¼ 2.264(11) Å. As in 1 and 2, the
Re e Re bond is long, Re(1) e Re(2) ¼ 3.3273(6) Å which can also be
attributed in part to the presence of the hydrido ligand H(1) which
also bridges the Re e Re bond [15]. The resonance of the hydrido
(b) R.N. Grimes, Coord. Chem. Rev. 200e202 (2000) 773e811;
(c) A.K. Saxena, N.S. Hosmane, Chem. Rev. 93 (1993) 1081e1124.
[
[
3] (a) L. Jain, V.K. Jain, N. Kushwah, M.K. Pal, A.P. Wadawale, V.I. Bregadze,
S.A. Glazun, Coord. Chem. Rev. 258e259 (2014) 72e118;
(b) R.N. Grimes, Carboranes, second ed., Elsevier, Amsterdam, 2011,
pp. 461e500. Ch. 9.13 e 9.15.
4] R.D. Adams, J. Kiprotich, D.V. Peryshkov, Y.O. Wong, Chem. Eur. J. 22 (2016)
ligand is also highly shielded at
tance, C(1) e C(2) ¼ 1.655(12) Å is significantly shorter than that
bond in the free molecule of [o-1,2-(SCH ]C 10, 1.8033(18) Å
17]. This might be due to the removal of electron density from the
d
¼ ꢁ15.68. The C e C bond dis-
6501e6504.
[5] R.D. Adams, J. Kiprotich, D.V. Peryshkov, Y.O. Wong, Inorg. Chem. 55 (2016)
3
)
2
2
B
10
H
8207e8213.
[
[
6] P.O. Nubel, T.L. Brown, J. Am. Chem. Soc. 106 (1984) 644e652.
7] S.V. Timofeev, M.V. Zakharova, E.M. Mosolova, I.A. Godovikov, I.V. Ananyev,
I.B. Sivaev, V.I. Bregadze, J. Organomet. Chem. 92 (2012) 721e722.
[
sulfur atoms because of their coordination to the metal atom Re(2).
The formation of the Re(1) e B(3) bond involved the oxidation
addition of the B(3) e H bond of the [o-1,2-(SCH ) ]C B H10 to
3 2 2 10
[8] J. Llop, C. Vi n~ as, F. Teixidor, L. Victori, R. Kivek €a s, R. Sillanp a€ a€ , Organometallics
0 (2001) 4024e4030.
2
[9] APEX2 Version 2014.9e0, SAINT Version 8.34A and SADABS Version 2014/4,
Re(1). The hydrogen atom became the hydrido ligand following the
elimination of the hexene from the original dirhenium reagent.
Compound 3 contains only seven linear terminal carbonyl ligands
which are distributed as shown in Fig. 3, but both metal atoms
achieve 18 electron configurations as a result of the existence of a
Re e Re single bond.
Bruker Analytical X-ray Systems, Inc., Madison, Wisconsin, USA, 2014.
[10] SAINTþ, Version 6.2a, Bruker Analytical X-ray Systems, Inc., Madison, WI,
2001.
[
11] APEX3 Version 2016.5e0 and SAINT Version 8.37A. Bruker AXS, Inc. Madison,
WI, USA.
[12] SADABS Version 2016/2 L. Krause, R. Herbst-Irmer, G.M. Sheldrick, D. Stalke,
J. Appl. Cryst. 48 (2015) 3e10.
13] G.M. Sheldrick, SHELXTL, Version 6.1, Bruker Analytical X-ray Systems, Inc.,
Madison, WI, 1997.
14] M.R. Churchill, K.N. Amoh, H.J. Wasserman, Inorg. Chem. 20 (1981)
1609e1611.
15] (a) R. Bau, M.H. Drabnis, Inorg. Chim. Acta 259 (1997) 27e50;
[
[
[
[
4
. Summary
(b) R.G. Teller, R. Bau, Struct. Bond. 41 (1981) 1e82.
Two new dirhenium compounds 1 and 2 were obtained from
16] (a) J.-H. Chung, E.P. Boyd, J. Liu, S.G. Shore, Inorg. Chem. 36 (1997)
2
the reaction of closo-o-(1-SCH
3
)C
2
B
10
H
11 with Re
2
(CO)
8
[
m-h
-C(H)
4778e4781;
Please cite this article in press as: R.D. Adams, J. Kiprotich, Journal of Organometallic Chemistry (2017), http://dx.doi.org/10.1016/
j.jorganchem.2017.09.004

6
R.D. Adams, J. Kiprotich / Journal of Organometallic Chemistry xxx (2017) 1e6
(
b) J.-H. Chung, D. Knoeppel, D. McCarthy, A. Columbie, S.G. Shore, Inorg.
Chem. 536e537 (1997) 537e539;
Chem. 32 (1993) 3391e3392;
(f) D.D. Ellis, A. Franken, F.G.A. Stone, Organometallics 18 (1999) 2362e2369.
(
(
(
c) D.-Y. Jan, S.G. Shore, Organometallics 6 (1987) 428e430;
d) S.A. Brew, F.G.A. Stone, Adv. Organomet. Chem. 35 (1993) 135e186;
e) V.N. Lebedev, D.F. Mullica, E.L. Sappenfield, F.G.A. Stone, J. Organomet.
[17] A. Laromaine, C. Vi n~ as, R. Sillanp €a €a , R. Kivek a€ s, Acta Cryst. C60 (2004)
o524eo526.
Please cite this article in press as: R.D. Adams, J. Kiprotich, Journal of Organometallic Chemistry (2017), http://dx.doi.org/10.1016/
j.jorganchem.2017.09.004