Bridging phenyl ligands. Unsaturated mercury-triosmium carbonyl cluster complexes containing bridging phenyl ligands

Article abstract of DOI:10.1016/j.jorganchem.2014.08.009

Abstract The gold phosphine group in the complex Os₃(CO)₁₀(μ-η¹-Ph)(μ-AuPPh₃), 1 can be replaced by mercury halide groups by reactions with mercury halides. The reaction of 1 with HgI₂ yielded the new

Full text of DOI:10.1016/j.jorganchem.2014.08.009

Journal of Organometallic Chemistry xxx (2014) 1e6
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Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Bridging phenyl ligands. Unsaturated mercury-triosmium carbonyl
cluster complexes containing bridging phenyl ligands
*
Richard D. Adams , Zhongwen Luo, Yuen Onn Wong
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 12 June 2014
Received in revised form
The gold phosphine group in the complex Os (CO)10(
3
m
-
h1-Ph)(
m
-AuPPh ), 1 can be replaced by mercury
3
halide groups by reactions with mercury halides. The reaction of 1 with HgI
2
yielded the new compound
yielded the new compound
, 3 in 18% yield. When heated to reflux in cyclohexane solvent, compound 2
was converted into the compound [Os (CO) -C )( -H)( -Hg)] Os(CO) , 4 in 11% yield. All new
compounds were characterized by single-crystal X-ray diffraction analyses. Compound 2 is a tetramer of
1
[
Os
Os
3
(CO)10
(CO)13
(
m
-
-
h
h
-Ph)(
m
-Cl)
-HgI)]
4 2
, 2 in 19% yield. The reaction of 1 with HgCl
31 July 2014
1
4
(
m
-Ph)(
m
3
Accepted 11 August 2014
Available online xxx
3
9
(
m
3
6
H
4
m
m
3
2
4
1
the unit “Os
3 4 4 2
(CO)10(m-h -Ph)(m-HgI)” that is held together by a cubane-like Hg I core having D sym-
Keywords:
Bridging phenyl
Osmium
Mercury
Cubane
metry. Each triosmium cluster is formally electronically unsaturated and contains one edge-bridging
1
phenyl ligand. Compound 3 contains a Os
bridges to an additional Os(CO) group via three bridging chloride ligands. Compound 4 contains two
Os (CO) -C )( -H)( -Hg) clusters that are linked by a bridging Os(CO) group. Each Os cluster in 4
contains a triply bridging C H4 benzyne ligand and one bridging hydrido ligand.
3
(CO)10(m-h -Ph)(m-Hg) cluster, but in this case the Hg atom
3
3
9
(
m
3
6
H
4
m
m
3
4
3
Benzyne
6
©
2014 Elsevier B.V. All rights reserved.
Introduction
The phenyl group typically coordinates to a single metal atom as
a
h1-ligand serving as a single electron donor, A [1]. Over the years,
a number of examples of polynuclear metal complexes containing
bridging aryl ligands have been reported. Bridging ligands can co-
1
1
ordinate as symmetrical
h -ligands, B [2,3] or asymmetrical, h -
semibridging ligands C [4] serving as one electron donors; as h2-D
ligands serving as three electron donors [5], or even as various
6
6
s
þ
p coordinated ligands m-h -E or m-h -F serving formally as 7-
electron donors [6,7]. Still other coordination modes exist and it
is likely that others will be found.
Recently, we reported a family of electronically unsaturated
1
triosmium carbonyl ligands Os
3
(CO)10
(m-
h
-Ar)(
m
-AuPPh
3
), 1,
Aryl ¼ phenyl ¼ Ph, 1, 2-naphthyl, 2-pyryl and 4-pyryl containing
8
bridging aryl ligands of the type B. Calculations showed that the
bonding of the ring to the metal atoms included a significant
amount
p-electron donation from the ring to the metal atoms.
When heated, these compounds eliminated CO and the edge-
bridging aryl ligand was converted into a triply-bridging aryne
ligand, e.g. eq. (1).
*
Corresponding author.
E-mail address: Adamsrd@mailbox.sc.edu (R.D. Adams).
http://dx.doi.org/10.1016/j.jorganchem.2014.08.009
022-328X/© 2014 Elsevier B.V. All rights reserved.
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R.D. Adams et al. / Journal of Organometallic Chemistry xxx (2014) 1e6
(
1)
3
3
In the present work, we have investigated the reactions of
complex 1 with mercuric halides. In the reaction of 1 with HgI , it
was found that the bridging Au(PPh ) group was replaced by a
bridging HgI group. The product of empirical formula “Os (CO)10
-HgI)”, then condensed by a self-assembly to form the
H
¼ 6 Hz, Ph), 8.31 (t, 1H, JH-H ¼ 6 Hz, Ph), 7.15 (t, 1H, JH-H ¼ 6 Hz,
3
2
Ph), 6.90 (t, 1H, JH-H ¼ 6 Hz, Ph). Mass Spec. EI/MS m/z: 2506 and
3
1256.
3
(m-
1
h
-Ar)(
tetramer, [Os
held together by formation of a rare cubane-shaped Hg
reaction of 1 with HgCl yielded the compound Os (CO)10
Hg)( -Cl) Os(CO) which contains an unsaturated phenyl
bridged Os cluster. This is linked to an Os(CO) group by a bridging
HgCl group. When heated compound 2 was converted to the new
compound yellow [Os (CO) -C )( -H)( -Hg)] Os(CO)
which contains two [Os (CO) -C )( -H)( -Hg)] clusters with
each having a triply bridging benzyne ligands. The two Os clusters
in 4 are linked by a bridging Os(CO) group. The results of our
m
1
3 6 5 3 2
Reaction of Os (CO)10(m-C H )(m-AuPPh ), 1 with HgCl
1.4 mg (0.078 mmol) of HgCl
0.040 mmol) of 1 dissolved in 50 mL of dichloromethane. The
reaction was heated to reflux for 15 min. The solvent was then
removed in vacuo, and the product was isolated by fractional
crystallization by using a hexane/methylene chloride solvent
mixture to give 10.0 mg (18% yield) of dark green Os
Ph)( -Hg)( -Cl) Os(CO) , 3. Spectral data for 3: IR CO (cm in
hexane): 2130(m), 2101(m), 2072(w), 2061(s), 2053(m), 2048(m),
3
(CO)10
(m
-
h
-Ar)(m-HgI)]
4
, 2, in the solid state that is
core. The
-Ph)(m-
2
2
was added to 56.0 mg
4 4
I
(
2
3
(
m
m
3
3
, 3
3
3
3
3
(CO)10(m-
3
9
(m
3
6
H
4
m
m
3
2
4
, 4
ꢀ
1
m
m
3
3
n
3
9
(m
3
6
H
4
m
m
3
3
1
2
2
2 2
032(w), 2020(m), 2012(s), 2000(m), 1987(w). H NMR (CD Cl ,
4
ꢁ
3
3
5 C, TMS, in ppm)
d
¼ 8.86 (d,1H, JH-H ¼ 6 Hz, Ph), 8.82 (d,1H, JH-
studies of the synthesis and characterizations of compounds 2e4
are described in this report.
Table 1
Crystallographic data for compounds 2, 3 and 4.
Experimental details
General data
Compound
2
3
4
Empirical formula Os12Hg
4
I
4
O
40
C
64
H
20 Os
4
3
HgCl O
13
C
19
H
5
7 2 22 34 10
Os Hg O C H
Reagent grade solvents were dried by the standard procedures
and were freshly distilled prior to use. Chromatographic separa-
tions were performed on Biobeads, S-X1 gel permeation beads
Formula weight
Crystal system
Lattice parameters
a (Å)
b (Å)
c (Å)
5021.56
Orthorhombic
1508.97
Triclinic
2503.00
Monoclinic
12.3967(4)
29.9460(9)
28.1291(8)
90.0
90.0
90.0
10442.4(6)
Ccca (#68)
4
3.19
21.6
9.1741(4)
29.1051(12)
10.9507(4)
14.7602(6)
90.00
97.999(1)
90.00
4658.6(3)
C2/c (#15)
4
2
00e400 mesh, that were obtained from Bio-Rad Laboratories.
10.0883(4)
16.2759(7)
82.851(1)
75.574(1)
89.921(1)
1446.83(11)
P‾-1 (#2)
2
Infrared spectra were recorded on a Thermo Nicolet Avatar 360 FT-
1
IR spectrophotometer. H NMR spectra were recorded on a Varian
a
b
g
(deg)
(deg)
Mercury 300 spectrometer operating at 300.1 MHz. Mass spectro-
metric (MS) measurements performed by a direct-exposure probe
using electron impact ionization (EI) were made on a VG 70S in-
(deg)
3
V (Å )
Space group
Z value
3 6 5 3
strument. Os (CO)10(m-C H )(m-AuPPh ), 1 was prepared according
r
calc (g/cm3)
3.46
23.12
3.57
25.65
to the previously reported procedure [8a].
ꢀ
m
(Mo K
a
) (mm 1
)
Temperature (K)
294(2)
49.40
294(2)
50.06
4328
361
294(2)
50.04
3657
297
1.075
Reaction of Os
3.4 mg (0.0955 mmol) of HgI
0.060 mmol) of Os (CO)10 -C )(
0 mL of dichloromethane. The reaction was heated to reflux for
5 min. The solvent was removed in vacuo, and the dark green
3
(CO)10
(
m
2
-C
6
H
5
)(
m
-AuPPh
3
), 1 with HgI
was added to 84.0 mg
-AuPPh ) and dissolved in
2
ꢁ
2
Qmax ( )
4
2
No. Obs. (I > 2
s(I)) 4157
(
3
1
3
(
m
6
H
5
m
3
No. Parameters
Goodness of
fit (GOF)
281
1.112
1.079
Max. shift in cycle 0.013
0.001
0.0287; 0.0616
0.025
0.0389; 0.1094
product was then isolated by chromatography on Bio-Beads by
using a 4:1 hexane/methylene chloride solvent mixture for elution.
a
Residuals :
R1; wR2
0.0347; 0.1004
Absorption
Correction,
Max/min
Multi-scan
1.00/0.503
Multi-scan
1.00/0.66
Multi-scan
1.00/0.39
16.3 mg (19% yield) of dark green crystals of [Os
3 6 5
(CO)10(m-C H )(m-
HgI)] , 2 were obtained following evaporation of the solvent. (Ph P)
4
3
AuI is the major colorless coproduct in this reaction. It can be
Largest peak
in Final Diff.
1.947
1.151
3.484
removed with difficulty by a series of fractional crystallizations.
ꢀ
1
ꢀ
3
Spectral data for 2: IR
n
CO (cm in hexane): 2100(m), 2057(s),
Map (e /Å )
1
2
2
049(m), 2021(m), 2013(s), 1995(m), 1984(w). H NMR (CD
2
Cl
2
,
a
R1 ¼ Shkl(rrFobsrꢀrFcalcrr)/ShklrFobsr; wR2 ¼ [Shklw(rFobsrꢀrFcalcr) /ShklwF2obs]1/2
2
;
ꢁ
3
3
2
2
1/2
5 C, TMS, in ppm)
d
¼ 8.95 (d,1H, JH-H ¼ 6 Hz, Ph), 8.76 (d,1H, JH-
w ¼ 1/
s
(Fobs); GOF ¼ [Shklw(rFobsrꢀrFcalcr) /(ndataꢀnvari)]
.
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R.D. Adams et al. / Journal of Organometallic Chemistry xxx (2014) 1e6
3
3
3
H
¼ 6 Hz, Ph), 8.30 (t, 1H, JH-H ¼ 6 Hz, Ph), 7.11 (t, 1H, JH-H ¼ 6 Hz,
3
Ph), 6.87 (t, 1H, JH-H ¼ 6 Hz, Ph). Mass Spec. EI/MS m/z: 1510.
3 9 3 6 4 3 2 4
Transformation of 2 into [Os (CO) (m -C H )(m-H)(m -Hg)] Os(CO) ,
4
1
4.2 mg (0.0058 mmol) of 2 was dissolved in cyclohexane. The
solution was heated to reflux for 70 min. The solvent was then
removed in vacuo. 1.5 mg (11% yield) of yellow [Os (CO)
)( -H)( -Hg)] Os(CO) , 4 was isolated by TLC on silica gel by
using a hexane/methylene chloride solvent mixture (4/1, v/v).
3
9 3
(m -
C
H
6 4
m
m
3
2
4
ꢀ
1
Spectral data for 4: IR nCO (cm in hexane): 2101(w), 2087(w),
2
080(m), 2070(s), 2052(s), 2024(w), 2017(m), 2012(w), 1996(m),
1
ꢁ
3
1989(m). H NMR (CD
2
Cl
2
, 25 C, TMS, in ppm)
d
¼ 7.93 (d, 1H, JH-
3
3
H
¼ 6 Hz, C
6
H
4
), 7.92 (d, 1H,
), 6.87 (d, 1H, JH-H ¼ 6 Hz, C
JH-H ¼ 6 Hz, C
6
H
4
), 6.88 (d, 1H,
J
H-
3
H
¼ 6 Hz, C
6
H
4
6
H
4
), -21.05 (s, 1H, hy-
dride); Mass Spec. EI/MS m/z: 2504.
Crystallographic analyses
Dark green single crystals of 2 and 3 suitable for X-ray diffrac-
tion analyses were obtained by slow evaporation of the solvent at
room temperature from solutions of the pure compound in hexane
solvent. Orange single crystals of 4 were obtained by slow evapo-
ration of solvent from a solution in hexane solvent at 5 C. The data
crystals were glued onto the end of thin glass fibers. X-ray intensity
Fig. 1. An ORTEP diagram of the molecular structure of [Os
showing 20% thermal ellipsoid probabilities. Hg is orange, I is purple, Os is blue and the
carbon atoms of the phenyl rings are colored red. Selected interatomic bond distances
3
(CO)10HgI(
m
-Ph)]
4
, 2
ꢁ
o
(Å) and angles ( ) are as follow: Os(1)
e
Os(2)
¼
2.8205(6) Å, Os(1) e
Os(3) ¼ 2.8761(6), Os(2) e Os(3) ¼ 2.8748(7), Os(1) e C(1) ¼ 2.309(12), Os(2) e
C(1) ¼ 2.285(12) Å, Os(1) e Hg(1) ¼ 2.7930(6) Å, Os(2) e Hg(1) ¼ 2.7978(7), Hg(1) e
data were measured by using a Bruker SMART APEX CCD-based
i
ii
I(1) ¼ 2.9112(8) Å, Hg(1) e I(1 ) ¼ 2.9645(8), Hg(1) e I(1 ) ¼ 3.524(1); Os(2) e Os(1) e
diffractometer using Mo K
a
radiation (
l
¼ 0.71073 Å). The raw
i
Os(3) ¼ 60.607(16), Os(1) e Hg(1) e Os(2) ¼ 60.596(15), I(1) e Hg(1) e I(1 ) ¼ 87.29(2),
i
data frames were integrated with the SAINTþ program by using a
narrow-frame integration algorithm [9]. Correction for Lorentz and
polarization effects were also applied with SAINTþ. An empirical
absorption correction based on the multiple measurement of
equivalent reflections was applied by using the program SADABS.
All structures were solved by a combination of direct methods and
difference Fourier syntheses and were refined by full-matrix least-
Hg(1) e I(1) e Hg(1 ) ¼ 91.11(2), Os(1) e C(1) e Os(2) ¼ 75.8(4). (For interpretation of
the references to color in this figure legend, the reader is referred to the web version of
this article.)
2
core having D symmetry. There are three independent Hg e I bond
i
distances: Hg(1) e I(1) ¼ 2.9112(8) Å, Hg(1) e I(1 ) ¼ 2.9645(8) Å
ii
and Hg(1) e I(1 ) ¼ 3.524(1) Å. Although transition metal halide
2
squares on F by using the SHELXTL software package [10]. All non-
cubanes are commonly found among the copper halide family of
complexes, they are rare among the Group IIB family of compounds
[11]. In fact, there has been only one previous structural verification
hydrogen atoms were refined with anisotropic displacement pa-
rameters. Hydrogen atoms were placed in geometrically idealized
positions and included as standard riding atoms during the least-
squares refinements. Crystal data, data collection parameters, and
results of the analyses are listed in Table 1. Compound 2 crystallized
in the orthorhombic crystal system. The space group Ccca was
indicated by the systematic absences in the data and confirmed by
the successful solution and refinement of the structure. The crystal
of a complex containing an Hg
complex anion [Hg I ]
8 20
4
I
4
cubane core. That was for the
[12]. The Hg e I distance in the cubane
core of this ion is 3.026(9) Å. Compound 2 contains four symmetry
equivalent Os (CO)10 -Ph) clusters. Each of which is linked to the
4
-
3
(m
cubane core via one bridging Hg atom. Each triosmium cluster in 2
contains ten linear carbonyl ligands and one edge-bridging phenyl
ligand. The latter which is analogous to the bridging phenyl ligand
in 1 serves as a 1-electron donor, B. Viewed as an uncharged
fragment the HgI group also serves as a 1-electron donor and
3
structure of 2 contains a significant void of 426 Å . The void
appeared to contain a highly disordered hexane molecule that was
cocrystallized from the crystallization solvent. Our efforts to devise
and refine a suitable disorder model were unsuccessful and the
void was ignored in the final refinements. Compound 3 crystallized
in the triclinic crystal system. The space group P-1 was confirmed
by the successful solution and refinement of the structure. Com-
pound 4 crystallized in the monoclinic crystal system. The space
group C2/c was indicated by the systematic absences in the data
and confirmed by the successful solution and refinement of the
structure. The Os e H distances in 4 were refined with distance
contraints of 1.80 Å.
3
therefore each Os cluster formally has only 46 valence electrons
instead of the expected 48 and is electronically unsaturated like
compound 1 [8a]. The unsaturation lies on the region of the
bridging phenyl ligand and the Os(1) e Os(2) bond, 2.8205(6) Å is
significantly shorter than the Os(1) e Os(3) ¼ 2.8761(6) Å and Os(2)
e Os(3) ¼ 2.8748(7) Å bonds. The analogous short bond in 1 is
significantly shorter, 2.7521(6) Å, than that in 2. The two inde-
pendent Os e Hg bond distances, Os(1) e Hg(1) ¼ 2.7930(6) Å,
Os(2) e Hg(1) ¼ 2.7978(7) Å, are slightly shorter than those found
to the bridging mercury atom in the compound [Os
3
(CO)10(m-
Results and discussion
Cl)] -Hg), 2.822(1) Å e 2.859(1) Å [13]. The Os e C distances to
2 4
(m
the bridging phenyl ligand are nearly equivalent, Os(1)
e
The reaction of Os
yielded the new compound [Os
yield. (Ph
Compound 2 was characterized by a single-crystal X-ray diffraction
analysis. An ORTEP diagram of the molecular structure of com-
pound 2 is shown in Fig. 1. Compound 2 is a tetramer of
3
(CO)10
(
m
ꢀ
h1ꢀPh)(
m
-AuPPh
3
), 1 with HgI
, 2 in 19%
2
C(1) ¼ 2.309(12) Å and Os(2) e C(1) ¼ 2.285(12) Å.
The bridging phenyl ligand in 1 was observed to undergo a
dynamical 2-fold rotation of the ring perpendicular to the Os e Os
3
(CO)10
(
m-Ph)( -HgI)]
m
4
3
P)AuI is the major colorless coproduct in this reaction.
1
bond on the H NMR timescale at elevated temperatures [8b].
Unfortunately, compound 2 is readily transformed thermally into
another product, see below, when heated so
a traditional
3 4 4
Os (CO)10(m-Ph)(m-HgI) that is held together by a cubane-like Hg I
temperature-dependent dynamic NMR investigation of 2 was not
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4
R.D. Adams et al. / Journal of Organometallic Chemistry xxx (2014) 1e6
possible. However, a 2D EXSY spectrum of 2 did show cross peaks
confirming the existence of exchange between the protons on the
ring carbons C(2) with C(6) and C(3) with C(5), see Fig. 2. This spin
transfer is best explained by a 2-fold rotational process similar to
that found in 1.
An electron impact mass spectrum of 2 did not show the parent
ion. The highest mass ions were attributed to the monomeric and
3
dimeric fragments of the empirical formula [Os (CO)10HgI(m-Ph)].
Evidently, the cubane cluster is split under the forcing conditions of
the mass spectrometer to yield the monomeric and dimeric
fragments.
2
The reaction of 1 with HgCl yielded the new compound
Os
4
(CO)13 -Ph)( -Cl) , 3 in 18% yield. Compound 3 was also
(
m
m
3
characterized by a single-crystal X-ray diffraction analysis. An
ORTEP diagram of the molecular structure of compound 3 is shown
in Fig. 3. Compound 3 contains a Os
similar that of 2, but in this case the Hg atom bridges to an addi-
tional Os(CO) group via three bridging chloride ligands. The Os e
3
(CO)10(m-Ph)(m-Hg) cluster
3
Os bond distances in 3 are similar to those in 2, Os(1) -
Os(2) ¼ 2.8275(6) Å, Os(1) e Os(3) ¼ 2.8676(6) Å, Os(2) e
Os(3) ¼ 2.8685(6) Å and the Os(1) e Os(2) bond that is bridged by
the phenyl ligand is again significantly shorter than the other two.
The Os e C bonds to the bridging phenyl ligand, Os(1) e
C(1) ¼ 2.343(12) Å, Os(2) e C(1) ¼ 2.302(12) Å, are very similar to
those in 1 and 2. The Os e Hg distances in 3, Os(1) e
Hg(1) ¼ 2.7522(6) Å, Os(2) e Hg(1) ¼ 2.7620(6) Å, are slightly
shorter than those in 2. The coordination geometry of the mercury
atom can be described as a distorted square pyramid with Os(1),
Os(2), Cl(1) and Cl(2) forming the square base and Cl(3) in the apical
position. The Hg e Cl distance to the apical Cl, Cl(3) is significantly
longer, Hg(1) e Cl(3) ¼ 2.983(3) Å than those to the basal Cl ligands,
Hg(1) e Cl(1) ¼ 2.797(3) Å, Hg(1) e Cl(2) ¼ 2.637(3) Å. Osmium
Os(4) must have been derived from a fragment of an original tri-
Fig. 3. An ORTEP diagram of the molecular structure of Os
3
(CO)10(m-Ph)(m-Hg)(m-
Cl) Os(CO) , 3 showing 30% thermal ellipsoid probability. Selected interatomic bond
3
3
o
distances (Å) and angles ( ) are as follow: Os(1) e Os(2) ¼ 2.8275(6), Os(1) e
Os(3) ¼ 2.8676(6), Os(2) e Os(3) ¼ 2.8685(6), Os(1) e C(1) ¼ 2.343(12), Os(2) e
C(1) ¼ 2.302(12), Os(1) e Hg(1) ¼ 2.7522(6), Os(2) e Hg(1) ¼ 2.7620(6), Hg(1) e
Cl(1) ¼ 2.797(3) Å, Hg(1) e Cl(2) ¼ 2.637(3) Å, Hg(1) e Cl(3) ¼ 2.983(3) Å, Os(4) e
Cl(1) ¼ 2.404(3), Os(4) e Cl(2) ¼ 2.432(3) Å, Os(4) e Cl(3) ¼ 2.404(3), Os(1) e Hg(1) e
Os(2) ¼ 61.698(16), Os(2) e Os(1) e Os(3) ¼ 60.482(15), Os(1) e C(1) e Os(2) ¼ 75.0(3).
established in this study. Os(4) contains three linear terminal
carbonyl ligands in a fac arrangement. Each of the three chloro li-
gands are coordinated to Os(4): Os(4) e Cl(1) ¼ 2.404(3), Os(4) e
Cl(2) ¼ 2.432(3) Å, Os(4) e Cl(3) ¼ 2.404(3) Å, to give a pseudo-
octahedral geometry. 2D EXSY H NMR spectra of the phenyl pro-
tons in 3 indicate the phenyl is also dynamically active as found in
compounds 1 and 2, see Supplementary Material.
3
osmium cluster and was captured by the Hg-bridged PhOs group
found in 3. The nature of the fragmentation process was not
The bonding in 3 can be viewed as a combination of a 46-
1
electron, positively charged Os
3
(CO)10
(mꢀ
h
ꢀPh)(
m-HgCl) frag-
-
3 2
ment linked to a negatively charged 16-electron [Os(CO) Cl ]
fragment. The latter would achieve an 18-electron configuration
when two electrons are donated to it from the Cl ligand on the Hg
atom in the Os fragment.
3
Fig. 4. An ORTEP drawing of the molecular structure of [Os
3 9 3 6 4 3
(CO) (m -C H )(m-H)(m -
Hg)] Os(CO) , 4 showing 30% thermal ellipsoid probability. Selected interatomic bond
2
4
o
distances (Å) and angles ( ) are as follow: Os(1) e Os(2) ¼ 2.7633(7), Os(1) e
Os(3) ¼ 2.8981(7), Os(2) e Os(3) ¼ 3.0214(7), Os(1) e Hg(1) ¼ 2.8575(7), Os(3) e
Fig. 2. A 2D EXSY H NMR spectrum of compound 2 (using 800 ms mixing time) for the
resonances of the protons on phenyl ring carbon atoms C(2) and C(6) at 8.94 ppm and
0
Hg(1) ¼ 2.8178(7), Os(4) e Hg(1) ¼ 2.6837(8), Hg(1)/Hg(1 ) ¼ 3.549(1), Os(1) e
8.76 ppm, and C(3) and C(5) at 7.15 ppm and 6.90 ppm. EXSY cross peaks are colored
C(1) ¼ 2.287(11), Os(1) e C(2) ¼ 2.402(12), Os(2) e C(2) ¼ 2.101(12), Os(3)
e
blue. (For interpretation of the references to color in this figure legend, the reader is
referred to the web version of this article.)
C(1) ¼ 2.121(12), Os(2) e H(1) ¼ 1.78(2), Os(3) e H(1) ¼ 1.79(2); Hg(1) e Os(4) -
0
Hg(1 ) ¼ 82.78(3).
Please cite this article in press as: R.D. Adams, et al., Journal of Organometallic Chemistry (2014), http://dx.doi.org/10.1016/
j.jorganchem.2014.08.009

R.D. Adams et al. / Journal of Organometallic Chemistry xxx (2014) 1e6
5
Scheme 1.
In earlier studies, it was shown that when compound 1 is heated
to reflux in octane solvent, the compound is decarbonylated and
the bridging phenyl ligand in 1 is converted into a bridging benzyne
ligand and a hydride ligand by cleavage of the CH bond on one of
the ortho-positioned carbon atoms [8a]. Similarly, when heated to
reflux in cyclohexane solvent, compound 2 was converted to the
the unsaturated osmium carbonyl cluster complexes 2 and 3 con-
1
taining
h
-bridging phenyl ligands. The HgI grouping in 2 has
assembly in the solid state.
adopted an unusual cubane e like Hg I
4 4
Compound 2 eliminates a CO ligand when heated and one of the
ortho-positioned CH bonds on the bridging phenyl ligand is cleaved
to form a bridging hydride ligand and a triply-bridging benzyne
ligand.
3 9 3 6 4 3 2 4
new compound [Os (CO) (m -C H )(m-H)(m -Hg)] Os(CO) , 4 in 11%
yield. Compound 4 was characterized by a single-crystal X-ray
diffraction analysis. An ORTEP diagram of the molecular structure
of compound 4 is shown in Fig. 4. Compound 4 contains two
Acknowledgments
Os
3
(CO)
9
(
m
3
-C
6
H
4
)(
m
-H)(
m
3
-Hg) clusters that are linked by
a
This research was supported by the U. S. National Science
Foundation, Grant CHE-1111496. We thank Dr. Mark Smith for
assistance with the X-ray structural analyses.
bridging Os(CO)
4
group. The Os(CO)
4
group must have originated
by a fragmentation of some of the triosmium clusters present in the
reaction solution. In the solid state, compound 4 lies on a 2-fold
rotational symmetry axis that passes through the Os atom of the
Os(CO)
Each Os
nine linear terminal carbonyl ligands (three on each osmium atom)
and one bridging hydrido ligand, H NMR
pected, the hydrido ligand was found to bridge the longest Os e Os
bond [14]. The Os e Hg distances to the bridging mercury atom
Appendix A. Supplementary material
4
group, so the two Os
3
clusters are symmetry equivalent.
3
cluster contains a triply bridging C
6 4
H
“benzyne” ligand,
CCDC 1007477e1007479 contains the supplementary crystal-
lographic data for this paper. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre via www.
ccdc.cam.ac.uk/data_request/cif.
1
d
¼ ꢀ21.05 ppm. As ex-
which is formally uncharged in
Hg(1) ¼ 2.8575(7) Å, Os(3) e Hg(1) ¼ 2.8178(7) Å, than those in 2,
but are similar to those in the compound [Os (CO)10 -Cl)] -Hg)
Os(CO) [13]. However, the Os e Hg distances to the unique osmium
atom Os(4), Os(4) e Hg(1) ¼ 2.6837(8) Å is significantly shorter. The
shortness may be due to reduced steric interactions about the Os(4)
e Hg(1) bond. The Hg(1) e Hg(1’) distance of 3.549(1) Å in 4 is too
long for any significant direct HgeHg bonding interaction. The
benzyne ligands in 4 serve as a four electron donors, so each tri-
osmium cluster contains a total 48 valence electrons. There is no
4 are longer, Os(1) e
Appendix B. Supplementary data
3
(m
2 4
(m
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.jorganchem.2014.08.009.
4
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j.jorganchem.2014.08.009