Facile cleavage of a phenyl group from SbPh3 by dirhenium carbonyl complexes

Article abstract of DOI:10.1016/j.jorganchem.2007.11.028

The complex Re₂(CO)₈[μ-η²-C(H){double bond, long}C(H)Buⁿ](μ-H) (1) reacts with SbPh₃ at 68 °C to yield the new σ-phenyl dirhenium complex Re₂(CO)₈(SbPh₃)(Ph)(μ-SbPh₂) (4) in 72% yield. Compound 4 contains two rhenium atoms held together by a bridging SbPh₂ ligand. One rhenium atom contains a σ-phenyl group. The other rhenium atom contains a SbPh₃ ligand. Compound 4 was also obtained in 34% yield from the reaction of Re₂(CO)₁₀ with SbPh₃ in the presence of UV-Vis irradiation together with some monorhenium products: HRe(CO)₄SbPh₃ (5), Re(Ph)(CO)₄SbPh₃ (6) and fac-Re(Ph)(CO)₃(SbPh₃)₂ (7) in low yields. Complex 4 is split by reaction with an additional quantity of SbPh₃ to yield the monorhenium SbPh₃ complexes 6, 7 and mer-Re(Ph)(CO)₃(SbPh₃)₂ (8) that contain a σ-phenyl ligand. When 4 was treated with hydrogen, the phenyl ligand was eliminated as benzene and the dirhenium complexes Re₂(CO)₈(μ-SbPh₂)(μ-H) (10), and Re₂(CO)₇(SbPh₃)(μ-SbPh₂)(μ-H) (11), were formed that contain a bridging hydrido ligand. The doubly SbPh₂-bridged dirhenium complex Re₂(CO)₇(SbPh₃)(μ-SbPh₂)₂ (9) that has no metal-metal bond was also formed in these two reactions.

Full text of DOI:10.1016/j.jorganchem.2007.11.028

Available online at www.sciencedirect.com
Journal of Organometallic Chemistry 693 (2008) 1636–1644
www.elsevier.com/locate/jorganchem
Facile cleavage of a phenyl group from SbPh3 by dirhenium
carbonyl complexes
Richard D. Adams *, Burjor Captain, William C. Pearl Jr.
Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, United States
Received 5 November 2007; received in revised form 15 November 2007; accepted 15 November 2007
Available online 22 November 2007
Dedicated to the memory of F.A. Cotton.
Abstract
The complex Re2(CO)8[l-g2-C(H)@C(H)Bun](l-H) (1) reacts with SbPh3 at 68 °C to yield the new r-phenyl dirhenium complex
Re2(CO)8(SbPh3)(Ph)(l-SbPh2) (4) in 72% yield. Compound 4 contains two rhenium atoms held together by a bridging SbPh2 ligand.
One rhenium atom contains a r-phenyl group. The other rhenium atom contains a SbPh3 ligand. Compound 4 was also obtained in
34% yield from the reaction of Re2(CO)10 with SbPh3 in the presence of UV–Vis irradiation together with some monorhenium products:
HRe(CO)4SbPh3 (5), Re(Ph)(CO)4SbPh3 (6) and fac-Re(Ph)(CO)3(SbPh3)2 (7) in low yields. Complex 4 is split by reaction with an
additional quantity of SbPh3 to yield the monorhenium SbPh3 complexes 6, 7 and mer-Re(Ph)(CO)3(SbPh3)2 (8) that contain a r-phenyl
ligand. When 4 was treated with hydrogen, the phenyl ligand was eliminated as benzene and the dirhenium complexes Re2(CO)8-
(l-SbPh2)(l-H) (10), and Re2(CO)7(SbPh3)(l-SbPh2)(l-H) (11), were formed that contain a bridging hydrido ligand. The doubly
SbPh2-bridged dirhenium complex Re2(CO)7(SbPh3)(l-SbPh2)2 (9) that has no metal–metal bond was also formed in these two reactions.
Ó 2007 Elsevier B.V. All rights reserved.
Keywords: Rhenium; Antimony; Triphenylstibine; Phenyl group cleavage
1. Introduction
Cleavage of a phenyl ring from the SnPh3 and GePh3
groups of the HSnPh3 and HGePh3 molecules is required
to form the bridging SnPh2 and GePh2 ligands, although
no intermediates were observed in the formation of these
products. However, in related studies, we have shown that
the reactions of HSnPh3 and HGePh3 with certain polynu-
clear metal carbonyl complexes proceed by initial oxidative
addition of the SnH or GeH bonds to metal cluster com-
plexes containing a hydrido ligand and a SnPh3 or GePh3
ligand by a process that results in an opening of the cluster.
When these compounds are heated, a phenyl ring is then
cleaved from the SnPh3 or GePh3 ligand which then com-
bines with a hydrido ligand and is eliminated as benzene
and bridging MPh2 ligands are formed in the cluster com-
plexes, see Scheme 1, M = Ge, Sn [2].
In recent studies, we have shown that the hexenyl-
bridged dirhenium complex Re2(CO)8[l-g2-C(H)@C(H)-
Bun](l-H) (1) readily reacts with HSnPh3 and HGePh3 to
yield the dirhenium complexes Re2(CO)8(l-SnPh2)2 (2)
and Re2(CO)8(l-GePh2)2 (3) that contain two bridging
SnPh2 ligands or GePh2 ligands, respectively, across a long
rhenium–rhenium bond [1].
Bun
H
Ph2
C
C
M
Ph3MH
Re
Re
ð1Þ
Re
Re
M = Sn (2)
M = Ge (3)
H
M
Ph2
1
Cleavage of phenyl groups from phosphine ligands is
also well known in reactions of metal carbonyl complexes
with PPh3 and related ligands [3]. These processes often,
*
Corresponding author. Tel.: +1 803 777 7187.
E-mail address: Adams@mail.chem.sc.edu (R.D. Adams).
0022-328X/$ - see front matter Ó 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2007.11.028

R.D. Adams et al. / Journal of Organometallic Chemistry 693 (2008) 1636–1644
1637
PBut3
PBut3
Pt
Pt
Ru
Ru
Ru
Ru
H
H
H
H
C
Pt
But3P
97 ˚C
-C6H6
Ru
Ru
Ru
Ru
Ru
H
C
H
Ru
C
Ru
MPh2
Ru
H
MPh3
Ru
+ Ph3MH,
M= Ge, Sn
Ru
Ru
-CO
M = Ge, Sn
Scheme 1.
but not always, proceed by ortho-metalation of the phenyl
ring. P–C bond cleavage may follow resulting in the forma-
tion of a bridging ‘‘benzyne” ligand. Leong et al. have
shown that phenyl groups can also be cleaved from SbPh3
in its reactions with triosmium and triruthenium carbonyl
complexes [4]. Because of the similarities between SbPh3
and HSnPh3, we decided to examine the reactions of SbPh3
with 1 and also with Re2(CO)10 under conditions of
UV–Vis irradiation. These results are reported here. Cleav-
age of a phenyl ring from the SbPh3 ligand to give products
containing r-coordinated phenyl groups is the dominant
mode of reaction with these dirhenium compounds.
Mass Spec. EI/MS m/z. 1302. The isotope pattern is consis-
tent with the presence of two rhenium atoms and two anti-
mony atoms. Elemental Anal. Calc.: C, 40.57; H, 2.32.
Found: C, 40.51; H, 2.54%.
(b) At 25 °C: 53.1 mg (0.150 mmol) of SbPh3 was added
to 33.0 mg (0.0483 mmol) of Re2(CO)8[l-g4-C(H)@C(H)-
Bun](l-H) in 20 mL of hexane. The reaction was allowed
to stir at room temperature for 24 h. The solvent was
removed in vacuo, and the product was then isolated by
TLC using a 4:1 hexane/methylene chloride solvent mix-
ture to give 15.6 mg (25% yield) of 4. A small amount of
1 (6%) was recovered from this reaction.
2. Experimental
2.3. Photolysis of Re2(CO)10 with SbPh3
2.1. General data
SbPh3 (104 mg, 0.2947 mmol) was added to a solution of
Re2(CO)10 in 20 mL of benzene in a 100 mL three-neck flask
equipped with a reflux condenser and a gas inlet. A slow
stream of nitrogen was allowed to flow through the flask
that was cooled to 0 °C and irradiated for 15 min. using a
high pressure mercury UV lamp (American Ultraviolet
Company, 1000 W) at the 250 wpi setting. The solvent
was removed in vacuo, and the products were then isolated
by TLC by using a 4:1 hexane/methylene chloride solvent
mixture to yield in order of elution the following: 3.7 mg
(4% yield) of colorless HRe(CO)4SbPh3, 5, 5.7 mg (5%
yield) of colorless Re(Ph)(CO)4SbPh3, 6, 4.0 mg (3% yield)
of colorless fac-Re(Ph)(CO)3(SbPh3)2, 7, and 31.7 mg
(34% yield) of colorless 4. Spectral data for 5. IR mCO
Reagent grade solvents were dried by the standard pro-
cedures and were freshly distilled prior to use. Infrared
spectra were recorded on a Thermo Nicolet Avatar 360
FT-IR spectrophotometer. 1H NMR spectra were recorded
on a Varian Mercury 300 spectrometer operating at
300.1 MHz. Mass spectrometric (MS) measurements per-
formed by a direct-exposure probe using electron impact
ionization (EI) were made on a VG 70S instrument.
Elemental Analyses were performed by Desert Analytics
(Tucson, AZ). SbPh3 and Re2(CO)10 were obtained from
STREM and were used without further purification. Re2-
(CO)8[l-g4-C(H)@C(H)Bun](l-H) was prepared according
to a previously reported procedure [5]. Product separations
were performed by TLC in air on Analtech 0.25 and
1
(cmꢀ1 in hexane): 2080(w), 1992(m), 1979(s), 1964(m). H
NMR (CDCl3, in ppm) d = 7.30–7.55 (m, 15H, Ph),
ꢀ6.00 (s, 1H, hydride). Elemental Anal. Calc.: C, 40.51;
H, 2.47. Found: C, 40.52; H, 2.50%. Spectral data for 6.
IR mCO (cmꢀ1 in hexane): 2083(m), 1996(m), 1982(s),
˚
0.5 mm silica gel 60 A F254 glass plates.
2.2. Reaction of Re2(CO)8[l-g4-C(H)@C(H)Bun](l-H)
(1) with SbPh3
1
1951(m). H NMR (CD2Cl2, in ppm) d = 7.20–7.65 (m,
15H, Ph), 6.81–6.93 (m, 5H, Ph–Re). Elemental Anal. Calc.:
C, 46.71; H, 2.77. Found: C, 45.93; H, 2.77. Spectral data
for 7. IR mCO (cmꢀ1 in hexane): 2017(s), 1940(m),
(a) At 68 °C: 104.5 mg (0.296 mmol) of SbPh3 was
added to 51.0 mg (0.07467 mmol) of Re2(CO)8[l-g4-
C(H)@C(H)Bun](l-H) in 80 mL of hexane. The reaction
was heated to reflux for 3 h. The solvent was removed in
vacuo, and the product was then isolated by TLC using a
4:1 hexane/methylene chloride solvent mixture. 70.0 mg
(72% yield) of Re2(CO)8(SbPh3)(Ph)(l-SbPh2) (4) was
obtained. Spectral data for 4: IR mCO (cmꢀ1 in hexane):
2087(m), 2072(m), 2012(m), 2007(m), 1998(s), 1979(m),
1
1912(m). H NMR (CD2Cl2, in ppm) d = 7.12–7.38 (m,
30H, Ph), 7.62 (m, 2H, Ph–Re), 6.68 (m, 1H, Ph–Re), 6.58
(m, 2H, Ph–Re). Mass Spec. EI/MS m/z. 1054. The isotope
pattern is consistent with the presence of one rhenium atom.
2.4. Reaction of 4 with SbPh3
1
1961(m), 1937(m), 1929(m). H NMR (CD2Cl2, in ppm)
SbPh3 (90.2 mg, 0.256 mmol) was added to a solution of
d = 7.08–7.63 (m, 25 H, Ph), 6.77–6.94 (m, 5H, Ph–Re).
4 (31.7 mg, 0.0243 mmol) in 20 mL of octane. The reaction

1638
R.D. Adams et al. / Journal of Organometallic Chemistry 693 (2008) 1636–1644
was heated to reflux for 3.5 h. The solvent was removed in
vacuo, and the products were then isolated by TLC by using
a 3:1 hexane/methylene chloride solvent mixture to yield in
order of elution the following: 4.8 mg (14% yield) of 6,
2.0 mg (4% yield) of mer-Re(Ph)(CO)3(SbPh3)2 (8), 1.1 mg
(3% yield) of Re2(CO)7(SbPh3)(l-SbPh2)2 (9), 2.0 mg (4%
yield) 7, 9.7 mg (31% recovered) of 4. Spectral data for 8.
from an octane/methylene chloride solvent mixture at room
temperature. Colorless single crystals of 5, 6, 9, 10 and 11
suitable for X-ray diffraction analyses were obtained by
slow evaporation of solvent from a hexane/methylene chlo-
ride solvent mixture at ꢀ25 °C. Colorless single crystals of
7 and 8 suitable for X-ray diffraction analyses were
obtained by slow evaporation of solvent from an octane/
benzene solvent mixture at room temperature. Each data
crystal was glued onto the end of a thin glass fiber. X-ray
intensity data were measured by using a Bruker SMART
APEX CCD-based diffractometer using Mo Ka radiation
IR mCO (cmꢀ1 in hexane): 1933(s), 1910(m) cmꢀ1 1H
.
NMR (CD2Cl2, in ppm) d = 7.15–7.67 (m, 30H, Ph),
6.52–6.93 (m, 5H, Ph–Re). Mass Spec. EI/MS m/z. 1054,
M+; 998, M+ꢀ2CO. The isotope pattern is consistent with
the presence of one rhenium atom. Spectral data for 9: IR
mCO (cmꢀ1 in hexane): 2072(m), 2024(w), 2008(vw),
1987(s), 1981(s), 1955(s), 1937(s), 1928(m). 1H NMR
(CD2Cl2, in ppm) d = 6.89–7.74 (m, 35H, Ph). EI/MS
m/z, 1474, M+, 1446, M+ꢀCO, 1418, M+ꢀ2CO, 1390,
M+ꢀ3CO. The isotope pattern is consistent with the pres-
ence of two rhenium atoms and three antimony atoms.
˚
(k = 0.71073 A). The raw data frames were integrated with
the SAINT+ program by using a narrow-frame integration
algorithm [6]. Correction for Lorentz and polarization
effects were also applied with SAINT+. An empirical absorp-
tion correction based on the multiple measurement of
equivalent reflections was applied using the program SAD-
ABS. All structures were solved by a combination of direct
methods and difference Fourier syntheses, and refined by
full-matrix least-squares on F2, using the SHELXTL software
package [7]. All non-hydrogen atoms were refined with
anisotropic displacement parameters. 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 Tables 1–3.
2.5. Reaction of 4 with H2
Compound 4 (44.5 mg, 0.0342 mmol) was dissolved in
25 mL of octane. While purging with H2 the reaction was
heated to reflux for 6.25 h. The solvent was removed in
vacuo, and the products were then isolated by TLC using
3:1 hexane/methylene chloride solvent mixture to yield in
order of elution the following: 9.4 (31% yield) Re2(CO)8-
(l-H)(l-SbPh2) (10), 3.7 mg (9% yield) Re2(SbPh3)(CO)7-
(l-SbPh2)(l-H) (11), 3.4 mg (7% yield) 9. Spectral data
for 10: IR mCO (cmꢀ1 in hexane): 2102(w), 2078(m),
Compounds 4, 5, 7, 10 and 11 all crystallized in the
ꢀ
triclinic crystal system. The space group P1 was assumed
Table 1
Crystallographic data for compounds 4 and 5
2009(s), 1997(s), 1971(s) cmꢀ1 1H NMR (CD2Cl2, in
.
Compound
4
5
ppm) d = 7.35–7.73 (m, 10 H, Ph), ꢀ16.341 (s, hydride,
1H). EI/MS m/z. 874, M+, 846, M+ꢀCO. The isotope pat-
tern is consistent with the presence of two rhenium atoms
and one antimony atom. Spectral data for 11: IR mCO
(cmꢀ1 in hexane): 2086(w), 2035(w), 2025(w), 1995(s),
Empirical formula
Formula weight
Crystal system
Re2Sb2O8C44H30
1302.58
Triclinic
ReSbO4C22H16
652.30
Triclinic
Lattice parameters
˚
a (A)
11.1865(4)
13.3720(5)
15.6059(6)
93.979(1)
95.802(1)
114.546(1)
2096.51(14)
9.5987(6)
10.9613(7)
11.1779(7)
71.178(1)
86.402(1)
84.894(1)
1108.04(12)
1959(m), 1940(m), 1931(m) cmꢀ1 1H NMR (CDCl3, in
.
˚
b (A)
˚
c (A)
ppm) d = 7.27–7.80 (m, Ph, 25H), ꢀ16.00 (s, hydride,
1H). EI/MS m/z.1198, M+, 1170, M+ꢀCO. The isotope
pattern is consistent with the presence of two rhenium
atoms and two antimony atoms.
a (°)
b (°)
c (°)
3
˚
V (A )
ꢀ
ꢀ
Space group
Z value
P1 ð#2Þ
P1 ð#2Þ
2
2
2.6. Detection of benzene formation
qcalc (g/cm3)
l (Mo Ka) (mmꢀ1
Temperature (K)
2Hmax (°)
Number of observed (I > 2r(I))
Number of parameters
Goodness-of-fit (GOF)
Maximum shift in cycle
Residualsa: R1; wR2
2.063
7.081
294(2)
56.64
8149
505
1.036
0.002
0.0289; 0.0597
Multi-scan,
1.000/0.810
1.349
1.955
6.699
294(2)
56.62
4720
257
1.044
0.001
0.0312; 0.0639
Multi-scan,
1.000/0.812
1.521
)
A 4.8-mg amount of 4 was dissolved in 0.6 mL of tolu-
ene-d8 in a 5 mm NMR tube. The NMR tube was evacuated
and filled with H2 five times. The NMR tube was heated in
an oil bath at 100 °C for 3 h. After this period of time the
NMR tube was taken out of the oil bath and cooled to
1
room temperature to acquire an H NMR spectrum. The
1H NMR spectrum of this solution showed a singlet at
Absorption correction,
maximum/minimum
d = 7.13 indicating the presence of benzene in solution.
Largest peak in final difference
ꢀ
3
˚
in map (e /A )
2.7. Crystallographic analyses
P
P
P
a
R = hkl(jjFobsj ꢀ jFcalcjj)/ hkljFobsj; Rw = [ hklw(jFobsj ꢀ jFcalcj)2/
P
P
1/2
hklwF2obs
]
;
w = 1/r2(Fobs); GOF = [ hklw(jFobsj ꢀ jFcalcj)2/(ndata
ꢀ
Colorless single crystals of 4 suitable for X-ray diffrac-
tion analyses were obtained by slow evaporation of solvent
nvari)]1/2
.

R.D. Adams et al. / Journal of Organometallic Chemistry 693 (2008) 1636–1644
1639
Table 2
Crystallographic data for compounds 6, 7 and 8
Table 3
Crystallographic data for compounds 9, 10 and 11
Compound 10
Empirical formula Re2Sb3O7C49H35 Re2SbO8C20H11 Re2Sb2O7C37H26
Formula weight
Crystal system
Lattice parameters
Compound
6
7
8
9
11
Empirical formula
Formula weight
Crystal system
ReSbO4C28H20 ReSb2O3C45H35 ReSb2O3C45H35
728.39
1053.43
Triclinic
1053.43
Monoclinic
1473.42
Orthorhombic
873.44
Triclinic
1198.48
Triclinic
Monoclinic
Lattice parameters
˚
˚
a (A)
16.9494(8)
12.0132(6)
13.6967(6)
90
110.199(1)
90
2617.4(2)
P21/c (#14)
4
10.4828(4)
11.0835(4)
19.2821(7)
81.904(1)
87.127(1)
66.110(1)
2027.9(1)
12.5817(4)
21.1773(6)
15.2322(5)
90
90.547(1)
90
4058.4(2)
P21/n (#14)
4
a (A)
18.9011(7)
22.0648(8)
22.5149(8)
90
90
90
9389.8(6)
Pca21 (# 29)
8
12.1374(6)
13.9418(6)
16.1462(7)
106.167(1)
106.119(1)
100.181 (1)
2423.55(19)
8.8885(4)
˚
˚
b (A)
b (A)
11.1834(5)
19.3107(9)
102.5820(1)
97.6860(1)
90.629 (1)
1855.03(15)
˚
˚
c (A)
c (A)
a (°)
b (°)
c (°)
a (°)
b (°)
c (°)
3
˚
3
˚
V (A )
V (A )
ꢀ
ꢀ
ꢀ
Space group
Z value
P1 ð#2Þ
Space group
Z value
P1 ð#2Þ
P1 ð#2Þ
2
4
2
qcalc (g/cm3)
l (Mo Ka) (mmꢀ1
Temperature (K)
2Hmax (°)
1.848
5.683
294(2)
56.62
1.725
4.337
294(2)
56.64
8086
1.724
4.334
294(2)
56.62
8051
qcalc (g/cm3)
l (Mo Ka) (mmꢀ1
Temperature (K)
2Hmax (°)
2.085
6.890
294(2)
50.06
12344
2.394
11.110
294(2)
52.04
6665
2.146
7.990
294(2)
52.04
5649
)
)
Number of observed 5093
Number of
(I > 2r(I))
observed
Number of
parameters
Goodness of fit
(GOF)
Maximum shift in
cycle
307
460
460
(I > 2r(I))
Number of
parameters
Goodness of fit
(GOF)
Maximum shift in 0.003
cycle
Residualsa: R1; wR2 0.0351; 0.0684
Absorption
correction,
maximum/
1090
565
427
1.000
0.002
1.049
0.001
1.075
0.002
1.011
0.991
0.001
1.081
0.000
Residualsa: R1; wR2 0.0264;0.0552 0.0357; 0.0694 0.0247; 0.0581
Absorption
correction,
maximum/
minimum
Multi-scan,
1.000/0.773
Multi-scan,
1.000/0.845
Multi-scan,
1.000/0.694
0.0401; 0.0908 0.0454; 0.0830
Multi-scan,
1.000/0.107
Multi-scan,
1.000/ 0.733
Multi-scan,
1.00/0.505
Largest peak in final 0.914
diꢀfference Map
2.301
1.314
minimum
Largest peak in
final diꢀfference
1.452
1.377
1.123
3
˚
(e /A )
3
˚
P
P
P
map (e / A )
a
R = hkl(jjFobsj ꢀ j Fcalcjj)/ hkljFobsj; Rw = [ hklw(jFobsj ꢀ j Fcalcj)2/
P
P
P
P
P
R = hkl(jjFobsj ꢀ jFcalcjj)/ hkljFobsj; Rw = [ hklw(jFobsj ꢀ jFcalcj)2/
a
hklw F2obs
]
1/2; w = 1/r2(Fobs); GOF = [ hklw(jFobsj ꢀ jFcalcj)2/(ndata
ꢀ
P
P
1/2
hklwF2obs
]
;
w = 1/r2(Fobs); GOF = [ hklw(jFobsj ꢀ jFcalcj)2/(ndata
–
nvari)]1/2
.
nvari)]1/2
.
and confirmed by the successful solution and refinement
for each of the structures. For compound 10 there were
two independent molecules present in the asymmetric unit.
The hydride ligand was located along the Re–Re bond in
each molecule and they were refined on their positional
parameters with a fixed isotropic thermal parameter. One
of the phenyl rings (C61–C66) in the structural analysis
of compound 11 was disordered over two orientations. It
was refined in 50/50 disorder model with isotropic thermal
parameters. The hydride ligand was located, and was
refined by using geometric restraints (a fixed Re–H bond
stages of refinement atoms C12 and C42A had negative
anisotropic thermal parameters. These two atoms were
subsequently refined with isotropic thermal parameters.
3. Results and discussion
Only one product Re2(CO)8(Ph)(SbPh3)(l-SbPh2) (4)
was obtained in 72% yield from the reaction of 1 with
SbPh3 in hexane solution by heating to reflux for 1 h see
Scheme 2.
The same product was obtained at 25 °C, but the yield
was much lower, 25% after 24 h. Compound 4 was charac-
˚
distance of 1.75 A) and an isotropic thermal parameter.
1
Compounds 6 and 8 crystallized in the monoclinic crys-
tal system. The space groups P21/c and P21/n, respectively
were identified uniquely on the basis of the systematic
absences in the intensity data. Compound 9 crystallized
in the orthorhombic crystal system. The systematic
absences were consistent with either of the space group
Pca21 or Pbcm. The structure could only be solved in the
former space group. With Z = 8 there are two independent
molecules present in the asymmetric unit. During the final
terized by a combination of IR, H NMR, mass spectral
and single-crystal X-ray diffraction analyses. An ORTEP
diagram of the structure 4 is shown in Fig. 1. The crystal
of 4 contains one complete formula equivalent in the asym-
metric crystal unit. The molecule contains the two rhenium
atoms that are bridged by a SbPh2 ligand. The rhenium
atoms are not mutually bonded, Re(1). . .Re(2) =
˚
4.785(1) A. The Re–Re bonding distance in Re2(CO)10 is
˚
3.042(1) A [8]. The Re–Re bond distance in
2 is

1640
R.D. Adams et al. / Journal of Organometallic Chemistry 693 (2008) 1636–1644
Bun
Re
Ph2
Sb
H
Ph2
Ph3Sb
SbPh3
H
Ph
C
C
Sb
Ph3Sb
Ph
+ SbPh3
68 oC
Re
Re
Re
+
Re
Re
Re
H
5, 4%
+
4, 34%
1
4, 72%
+ SbPh3
Re2(CO)10
+
hν
273 K
Scheme 2.
SbPh3
SbPh3
SbPh3
Re
Re
+
Ph
6, 5%
Scheme 3.
Ph
7, 3%
yield and fac-Re(Ph)(CO)3(SbPh3)2, 7, 3% yield. Each of
1
the new products was characterized by IR, H NMR and
a single crystal X-ray diffraction analysis.
An ORTEP diagram of the molecular structure of 5 is
shown in Fig. 2. Compound 5 contains only one rhenium
atom. It has four terminal carbonyl ligands, one SbPh3
ligand and a hydride ligand, H(1). The source of the
hydride ligand has not been identified. The Re–Sb distance
is similar to that found to the SbPh3 ligand found in com-
˚
pound 4, Re(1)–Sb(1) = 2.6931(4) A. The hydrido ligand
Fig. 1. An ORTEP diagram of the molecular structure of Re2(CO)8-
was located and refined crystallographically. It is posi-
tioned cis to the SbPh3 ligand and it exhibits the usual
characteristic high field resonance shift in its 1H NMR
spectrum, d = ꢀ6.00. The Re–H bond distance, Re(1)–
(SbPh3)(Ph)(l-SbPh2) (4) showing 30% thermal ellipsoid probability.
˚
Selected interatomic bond distances (A) and angles (°) are as follows:
˚
Re(1). . .Re(2) = 4.785(1) A,
Re(1)–C(1) = 2.228(5),
Re(1)–Sb(1) =
2.7676(4), Re(2)–Sb(2) = 2.7329(4), Re(2)–Sb(1) = 2.8159(4); C(1)–
Re(1)–Sb(1) = 91.67(12), Sb(2)–Re(2)–Sb(1) = 101.176(11), Re(1)–Sb(1)–
Re(2) = 117.96(1).
˚
H(1) = 1.78(5) A, is similar to the Re–H bond distances
that were observed in the related phosphine com-
˚
pounds, fac-Re(H)(CO)3[Ph2P(CH2)3PPh2], 1.70(4) A [11];
˚
˚
3.1685(3) A in its monoclinic form and 3.1971(4) A in a
triclinic form [1]. The bridging SbPh2 is slightly asymmetri-
cal in its bonding to the two rhenium atoms, Re(1)–
˚
fac-Re(H)(CO)3[Ph2P(CH2)4PPh2], 1.75(4) A [11]; Re(H)-
˚
(CO)4P(OMe)Ph2], 1.60(8) A [12] and mer-Re(H)(CO)3-
˚
(P(OMe)Ph2)2, 1.70(6) A [12].
˚
˚
Sb(1) = 2.7676(4) A and Re(2)–Sb(1) = 2.8159(4) A. This
could be due to steric effects since Re(2) contains a bulky
SbPh3 ligand in addition to the four terminal carbonyl
ligands, while Re(1) has only the smaller r-phenyl group
with its four terminal carbonyl ligands. Both Re–Sb dis-
tances in 4 are slightly longer than those found for the
bridging SbPh2 ligand in the compound Re2(CO)7-
˚
(SbPh3)(l-PPh2)(l-SbPh2) (12), Re–Sb = 2.748(2) A and
Re(2)–Sb(1) = 2.731(1) A, which contains two ligands
˚
bridging the two metal atoms [9]. Compound 4 contains
one SbPh3 ligand coordinated to the metal atom Re(2).
The Re–Sb distance is slightly shorter, Re(2)–Sb(2) =
˚
2.7329(4) A, than those of the bridging SbPh2 ligand, but
it is longer than the Re–Sb bond distance to the SbPh3
˚
ligand in 12, Re–Sb = 2.671(1) A [9]. The Re–C distance
˚
to the phenyl ring, Re(1)–C(1) = 2.228(5) A, is only slightly
longer than the Re–C distance to the phenyl ring in the
˚
compound (C5Me5)Re(CO)2I(Ph), 2.191(5) A [10].
Compound 4 was also the major product obtained from
the reaction of SbPh3 with Re2(CO)10 in the presence of
UV–Vis irradiation, but the yield was much lower, 34%
yield. In addition to 4, three minor products were obtained
from this reaction, see Scheme 3. These were identified as
HRe(CO)4SbPh3, 5, 5% yield; Re(Ph)(CO)4SbPh3, 6, 3%
Fig. 2. An ORTEP diagram of the molecular structure of HRe(CO)4-
SbPh3 (5), showing 30% thermal ellipsoid probability. Selected interatomic
˚
bond distances (A) and angles (°) are as follows: Re(1)–Sb(1) = 2.6931(4),
Re(1)–H(1) = 1.78(5), Re(1)–C(14) = 1.952(5), Re(1)–C(12) = 1.965(5),
Re(1)–C(11) = 1.981(5), Re(1)–C(13) = 1.987(5); Sb(1)–Re(1)–H(1) =
79.7(17).

R.D. Adams et al. / Journal of Organometallic Chemistry 693 (2008) 1636–1644
1641
An ORTEP diagram of the structure of 6 is shown in
Fig. 3. Compound 6 is very similar to 5. It contains only
one rhenium atom, four terminal carbonyl ligands, one
SbPh3 ligand and a r-phenyl ligand located cis to the
SbPh3 ligand. The Re–Sb distance is similar to that found
ligands have the fac structure. The Re–Sb distances are
very similar to those in 4, 5 and 6, Re(1)–Sb(1) =
2.7176(4) A, Re(1)–Sb(2) = 2.7151(3) A. The Re–C dis-
˚
˚
tance to the phenyl ring is very similar to that in 6,
˚
Re(1)–C(14) = 2.214(5) A.
˚
in compounds 4 and 5, Re(1)–Sb(1) = 2.7124(3) A. The
The reaction of 4 with SbPh3 in an octane solution at
reflux for 3.5 h provided compounds 6 and 7 in low yields,
but also provided two new compounds mer-Re(Ph)-
(CO)3(SbPh3)2 (8) in 4% yield and of Re2(CO)7(SbPh3)-
(l-SbPh2)2 (9) in 3% yield. Thirty percent of the 4 was
recovered after the 3.5 h reaction period.
Re–C distance to the phenyl ring, Re(1)–C(15) =
˚
2.226(4) A, is very similar to the Re–C distance found in
4 and the compound Cp*Re(CO)2(I)Ph, [10].
Compound 7 is a SbPh3 derivative of 6. An ORTEP dia-
gram of the structure of 7 is shown in Fig. 4. The three CO
An ORTEP diagram of the structure of 8 is shown in
Fig. 5. Compound 8 is an isomer of 7. The three CO
ligands have a mer structure with the two SbPh3 ligands
occupying trans-coordination sites, Sb(1)–Re(1)–Sb(2) =
176.683(3)°. The Re–Sb distances are significantly shorter
˚
than those in 4, 5 and 6, Re(1)–Sb(1) = 2.6482(2) A and
˚
Re(1)–Sb(2) = 2.6449(2) A. The Re–C distance to the
r-bonded phenyl ring is similar to that in 6 and 7,
˚
Re(1)–C(14) = 2.214(5) A (see Scheme 4).
Compound 9 crystallizes with two independent mole-
cules in the asymmetric crystal unit. Both molecules are
structurally similar. An ORTEP diagram of the structure
of one of two crystallographically independent molecules
of 9 is shown in Fig. 6. Compound 9 is a dirhenium
complex similar to 4, but it contains two bridging SbPh2
ligands. The Re–Re distance in 9, Re(1)–Re(2) =
˚
˚
4.394(1) A, Re(3)–Re(4) = 4.391(1) A, is shorter than that
˚
in 4, 4.785(1) A, but much longer than that in 2,
˚
˚
3.1685(3) A (3.1971(4) A) which contains a Re–Re bond
[1]. In fact, both metals in 9 have 18 electron configurations
on the basis of their ligand content, so there is no need to
Fig. 3. An ORTEP diagram of the molecular structure of Re(Ph)-
(CO)4SbPh3 (6), showing 30% thermal ellipsoid probability. Selected
˚
interatomic bond distances (A) and angles (°) are as follows: Re(1)–
Sb(1) = 2.7124(3),
Re(1)–C(15) = 2.226(4),
Re(1)–C(14) = 1.984(4),
Re(1)–C(12) = 1.984(4), Re(1)–C(11) = 1.929(4), Re(1)–C(13) = 1.952(5);
Sb(1)–Re(1)–C(15) = 85.65(8).
Fig. 4. An ORTEP diagram of the molecular structure of fac-
Re(Ph)(CO)3(SbPh3)2 (7), showing 30% thermal ellipsoid probability.
Selected interatomic bond distances (A) and angles (°) are as follows: Re(1)–
Fig. 5. An ORTEP diagram of the molecular structure of mer-
Re(Ph)(CO)3(SbPh3)2 (8), showing 30% thermal ellipsoid probability.
Selected interatomic bond distances (A) and angles (°) are as follows: Re(1)–
˚
˚
Sb(1) = 2.7176(4), Re(1)–Sb(2) = 2.7151(3), Re(1)–C(14) = 2.214(5),
Re(1)–C(12) = 1.950(5), Re(1)–C(11) = 1.914(5), Re(1)–C(13) = 1.922(6);
Sb(1)–Re(1)–C(14) = 92.48(11), Sb(2)–Re(1)–C(14) = 83.33(11), Sb(1)–
Re(1)–Sb(2) = 97.669(11).
Sb(1) = 2.6482(2), Re(1)–Sb(2) = 2.6449(2), Re(1)–C(14) = 2.230(3),
Re(1)–C(12) = 1.940(4), Re(1)–C(11) = 1.967(4), Re(1)–C(13) = 1.980(4);
Sb(1)–Re(1)–C(14) = 91.80(7), Sb(2)–Re(1)–C(14) = 84.99(7), Sb(1)–
Re(1)–Sb(2) = 176.683(3).

1642
R.D. Adams et al. / Journal of Organometallic Chemistry 693 (2008) 1636–1644
SbPh3
SbPh3
SbPh3
Ph
7, 4%
Re
Re
+
Ph
Ph2
Sb
6, 14%
Ph3Sb
Ph
+ SbPh3
125 oC
Re
Re
+
+
Ph2
Sb
SbPh3
Re
SbPh3
Ph
4
Re
Re
+
Ph3Sb
Sb
Ph2
8, 4%
9, 3%
Scheme 4.
˚
˚
˚
˚
Re(2)–Sb(1) = 2.7772(13) A, Re(3)–Sb(4) = 2.7753(12) A,
Re(4)–Sb(5) = 2.7546(12) A, Re(4)–Sb(4) = 2.7753(12) A
˚
˚
are similar to those 12, 2.748(2) A and 2.731(1) A and in
4, see above. The Re–Sb distances to the terminally coordi-
nated SbPh3 ligands are similar than those in 4, 5, 6, 7
˚
and 12, Re(1)–Sb(3) = 2.7412(18) A and Re(4)–Sb(6) =
˚
2.7410(18) A.
When hydrogen was purged through an octane solution
of 4 at reflux for 3.5 h, three compounds were formed.
These included 9 in a slightly higher yield 7%, and two
new compounds 10 and 11 in 31% and 9% yields, respec-
tively, see Scheme 5.
The coproduct benzene was observed spectroscopically
(1H NMR) when the reaction was performed under hydro-
gen in an NMR tube in d8-toluene solvent at 100 °C.
Compounds 10 and 11 were both characterized crystallo-
graphically. Compound 10 contains two crystallographi-
cally independent molecules in the asymmetric crystal
unit. Both molecules are structurally similar. Compound
11 is simply a SbPh3 derivative of 10. ORTEP diagrams
of the molecular structures of 10 and 11 are shown in Figs.
7 and 8, respectively. Both compounds contain two mutu-
ally bonded rhenium atoms that are bridged by a SbPh2
ligand and a hydrido ligand. The Re–Re bond distances
Fig. 6. An ORTEP diagram of the molecular structure of Re2(CO)7-
(SbPh3)(l-SbPh2)2 (9), showing 30% thermal ellipsoid probability.
˚
Selected interatomic bond distances (A) are as follows: Re(1). . .Re(2) =
4.394(1), Re(3). . .Re(4) = 4.391 (1), Re(1)–Sb(3) = 2.7412(18), Re(1)–
Sb(2) = 2.7638(12), Re(1)–Sb(1) = 2.7670(13), Re(2)–Sb(2) = 2.7655(13),
Re(2)–Sb(1) = 2.7772(13),
Re(3)–Sb(5) = 2.7669(12),
Re(3)–Sb(4) =
2.7753(12), Re(4)–Sb(6) = 2.7410(18), Re(4)–Sb(5) = 2.7546(12), Re(4)–
Sb(4) = 2.7753(12).
˚
˚
˚
are 3.2244(6) A [3.2396(5) A] in 10 and 3.2574(5) A in 11.
The slightly longer length of the Re–Re bond in 11 is prob-
ably due to steric interactions caused by the bulky SbPh3
ligand on the atom Re(2). The Re–Re bond distance in
the related phosphido complex Re2(CO)8(l-PPh2)(l-H) is
expect the presence of a metal–metal bond. One rhenium
atom in 9 has four CO ligands and the other rhenium atom
has three CO ligands and one SbPh3 ligand that lies cis to
the two bridging SbPh2 ligands. Compound 9 is structur-
ally very similar to 12 [9]. The Re–Sb distances to the
˚
slightly shorter at 3.165(1) A, possibly because the phos-
phorus atom is smaller than the antimony atoms in 10
and 11 [13]. The Re–Sb bond distances to the bridging
SbPh2 ligand in 10 are slightly shorter than those in 4
˚
bridging SbPh2 ligands Re(1)–Sb(2) = 2.7638(12) A,
˚
˚
Re(1)–Sb(1) = 2.7670(13) A, Re(2)–Sb(2) = 2.7655(13) A,
Ph
Sb
Ph
Sb
Ph
Sb
Ph
Sb
2
2
2
2
SbPh
Re
+H
3
2
Ph Sb
3
Ph
+
Re
+
Re
Re
Re
Re
Re
Re
-C H
6
Sb
Ph
H
H
6
SbPh
3
2
4
9, 7%
Scheme 5.
10, 31%
11, 9%

R.D. Adams et al. / Journal of Organometallic Chemistry 693 (2008) 1636–1644
1643
trans to the short Re–Sb bond, Sb(1)–Re(2)–Sb(2) =
157.09(3)°. The shortness of the proximate Re–Sb bond is
thus probably the result of a weaker structural trans-effect
due to the different p-backbonding properties of the SbPh3
ligand compared to that of CO ligands that lie trans to
both Re–Sb bonds in 10 and in 11. Compound 10 is struc-
turally similar to the compound Re2(CO)7(PPh3)(l-PPh2)-
(l-H) [14]. A similar structural trans-effect was observed
in the Re–P bond distances involving the bridging PPh2
ligand in this molecule. Compounds 10 and 11 both con-
tain bridging hydrido ligands that lie opposite to the bridg-
ing SbPh2 ligand. The hydrido ligand was located and
refined in the structural analyses of 10: Re(1)–
˚
˚
H(1) = 1.98(7) A, Re(2)–H(1) = 1.70(7) A, [Re(3)–H(2) =
˚
˚
2.00(7) A, Re(4)–H(2) = 1.82(7) A]. The bridging hydrido
ligand in 11 was located and refined with geometric con-
straints. As expected, both hydride ligands exhibit very
1
high field resonance shifts in the H NMR spectrum of
the compounds: d = ꢀ16.34 for 10 and ꢀ16.00 for 11.
Fig. 7. An ORTEP diagram of the molecular structure of Re2(CO)8(l-
SbPh2)(l-H) (10) showing 30% thermal ellipsoid probability. Selected
interatomic bond distances (A) and angles (°) are as follows: Re(1)–
Re(2) = 3.2244(6), Re(1)–Sb(1) = 2.6934(7), Re(1)–H(1) = 1.98(7), Re(2)–
˚
4. Summary
Sb(1) = 2.6983(7),
Re(2)–H(1) = 1.70(7),
Re(3)–Sb(6) = 2.6983(8),
It has been shown that a phenyl group is readily cleaved
from SbPh3 in its reactions with the rhenium carbonyl
complexes 1 and Re2(CO)10. The novel r-phenyl complex
4 was formed by insertion of a rhenium atom into the
Sb–C(phenyl) bond. The rhenium–rhenium bond was also
cleaved in the process. Interestingly, even in the reaction of
SbPh3 with 1 at room temperature, there was no evidence
for formation of the compound Re2(CO)8(SbPh3)2, a likely
intermediate in the formation of 4, even though the bis-
PPh3 complex Re2(CO)8(PPh3)2 is stable and well known
[14]. It must be that the Sb–C cleavage process is simply
too facile even at this low temperature. The dirhenium
complex 4 is split by reaction with an additional quantity
of SbPh3 to yield a series of monorhenium SbPh3 com-
plexes 6–8 containing a r-phenyl ligand. When 4 was trea-
ted with hydrogen, the phenyl ligand was eliminated and
the dirhenium complexes 10 and 11 were formed that con-
tain a bridging hydrido ligands. The doubly SbPh2-bridged
dirhenium complex 9 that has no metal–metal bond was
also formed in these two reactions.
Re(3)–Re(4) = 3.2396(5), Re(3)–H(2) = 2.00(7), Re(4)–Sb(6) = 2.6969(7),
Re(4)–H(2) = 1.82(7).
Acknowledgement
Fig. 8. An ORTEP diagram of the molecular structure of Re2(CO)7-
(SbPh3)(l-SbPh2)(l-H) (11) showing 30% thermal ellipsoid probability.
˚
Selected interatomic bond distances (A) and angles (°) are as follows:
This research was supported by the Office of Basic
Energy Sciences of the US Department of Energy under
Grant No. DE-FG02-00ER14980.
Re(1)–Re(2) = 3.2574(5), Re(1)–Sb(1) = 2.6948(7), Re(2)–Sb(1) = 2.6426(7),
Re(2)–Sb(2) = 2.6430(7); Sb(1)–Re(2)–Sb(2) = 157.09(3).
and 9 and are nearly equal in length: Re(1)–Sb(1) =
Appendix A. Supplementary material
˚
˚
2.6934(7) A, Re(2)–Sb(1) = 2.6983(7) A, [Re(3)–Sb(6) =
˚
˚
2.6983(8) A, Re(4)–Sb(6) = 2.6969(7) A]. In contrast, the
CCDC 666183, 666184, 666185, 666186, 666187,
666188, 666189 and 666190 contain the supplementary
crystallographic data for compounds 4, 5, 6, 7, 8, 9, 10
and 11, respectively. These data can be obtained free of
charge from The Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data_request/cif. Supplementary
Re–Sb bond distances to the bridging SbPh2 ligand in 11
˚
are significantly different, Re(1)–Sb(1) = 2.6948(7) A,
˚
Re(2)–Sb(1) = 2.6426(7) A with the shorter distance being
associated with the rhenium atom that contains the bulky
SbPh3 ligand. The SbPh3 ligand in 11 lies approximately

1644
R.D. Adams et al. / Journal of Organometallic Chemistry 693 (2008) 1636–1644
(g) S.C. Brown, J. Evans, M.J. Webster, J. Chem. Soc., Dalton
Trans. (1980) 1021;
(h) R.D. Adams, B. Captain, W. Fu, M.D. Smith, J. Organomet.
Chem. 651 (2002) 124.
data associated with this article can be found, in the online
version, at doi:10.1016/j.jorganchem.2007.11.028.
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