Rhenium-bismuth carbonyl cluster compounds

Article abstract of DOI:10.1021/ic901176x

The reaction of Re₂(CO)₈[μ-η² -C(H)=C(H)Buⁿ](μ-H) with BiPh₃ in heptane solvent at reflux yielded three new compounds Re₂(CO)₈(μ-BiPh ₂)₂,1 (14% yield), [Re

Full text of DOI:10.1021/ic901176x

Inorg. Chem. 2009, 48, 9519–9525 9519
DOI: 10.1021/ic901176x
Rhenium-Bismuth Carbonyl Cluster Compounds
Richard D. Adams* and William C. Pearl, Jr.
Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina 29208
Received June 19, 2009
The reaction of Re2(CO)8[μ-η2-C(H)dC(H)Bun](μ-H) with BiPh3 in heptane solvent at reflux yielded three new
compounds Re2(CO)8(μ-BiPh2)2, 1 (14% yield), [Re(CO)4(μ-BiPh2)]3, 2 (5% yield), and Re2(η6-C6H5Ph)(CO)7, 3, 4.7
mg (7% yield). Compound 1 contains two Re(CO)4 groups joined by two bridging BiPh2 ligands in a four-membered ring.
˚
There is no Re-Re bond in 1, Re Re=4.483(1) A. Compound 2 contains a six-membered Re3Bi3 ring in a twist-boat
3 3 3
conformation. When heated to 110 °C in toluene, compound 1 was transformed into the heterocycle 2 (8% yield), the
known compound Re(CO)5Ph, 4 (25% yield), and the new compound Re2(CO)8(μ-BiPh)2, 5 (4% yield). Compound 5
contains two Re(CO)4 groups joined by two bridging BiPh ligands and a Re-Re bond, Re-Re=3.1006(18) A. When
˚
compound 2 was heated to reflux in an octane solution, it was converted to two new compounds: cis-Re4(CO)16-
(μ-BiPh2)2(μ4-BiPhBiPh), cis-6 and trans-Re4(CO)16(μ-BiPh2)2(μ4-BiPhBiPh), trans-7 and a small amount of 1 (3%
yield). cis-6 and trans-7 are isomers. Both compounds contain two fused Re2Bi3 rings that share a quadruply bridging
˚
˚
BiPhBiPh ligand that contains a Bi-Bi bond; Bi-Bi = 3.0237(7) A in cis-6 and Bi-Bi = 2.9765(3) A in trans-7. The
phenyl groups on the bridging BiPhBiPh ligand in cis-6 have a cis-orientation and in trans-7 they have a trans-orientation.
In the presence of visible light, cis-6 and trans-7 are transformed into yet another isomer Re4(CO)16(μ-BiPh2)2-
(μ-BiBiPh2), 8, by a shift of one of the phenyl ligands on the bridging BiPhBiPh ligand to the neighboring bismuth atom.
Compound 8 contains two fused rings, one five-membered Re2Bi3 ring, and one four-membered Re2Bi2 ring.
Introduction
and ammoxidation reactions of hydrocarbons, eqs
4-5.4,5
Bismuth complexes have been shown to catalyze a variety
of important organic reactions, for example, eqs 1,1-2,2
including the formation of C-N bonds, for example, eq 3.3
It has been shown that nanoparticles of rhenium-anti-
mony and rhenium-bismuth serve as effective catalysts for
the ammoxidation of 3-picoline to nicotinonitrile which is a
precursor to nicotinic acid, also known as niacin or vitamin
B3, eq 6.6 These catalysts were derived from rhenium-anti-
mony and rhenium-bismuth carbonyl complexes.6
Bismuth molybdate has been found to be a valu-
able catalyst for industrially important oxidation
Heterobimetallic complexes containing bismuth have
been shown to be good precursors to heterobimetallic
*To whom correspondence should be addressed. E-mail: adams@mail.
chem.sc.edu.
(1) Gaspard-Illoughmane, H.; Le Roux, C. Eur. J. Org. Chem. 2004, 2517–2532.
(2) Oussaid, A.; Garrigues, B. Phosphorus, Sulfur Silicon Relat. Elem.
2002, 177, 825–832.
(3) Wei, H.; Qian, G.; Xia, Y; Li, K.; Li, Y.; Li, W. Eur. J. Org. Chem.
2007, 4471–4474.
(4) Moro-Oka, Y.; Ueda, W. Adv. Catal. 1994, 40, 233–273.
(5) (a) Grasselli, R. K. Catal. Today 1999, 49, 141–153. (b) Jang, Y. H.;
Goddard, W. A. J. Phys. Chem. B 2002, 106, 5997–6013.
(6) Raja, R.; Adams, R. D.; Blom, D. A.; Pearl, W. C., Jr.; Gianotti, E.;
Thomas, J. M. Langmuir 2009, 25, 7200–7204.
r
2009 American Chemical Society
Published on Web 08/27/2009
pubs.acs.org/IC

9520 Inorganic Chemistry, Vol. 48, No. 19, 2009
Adams and Pearl
nanomaterials.6-7 Although a number of bismuth-transition
metal carbonyl complexes have been prepared and structu-
rally characterized over the years,8 the field of rhe-
nium-bismuth cluster chemistry is extremely underdeve-
loped. We have recently begun investigations of the synthesis
of polynuclear rhenium-bismuth carbonyl complexes. Here
we report the syntheses and characterizations of six new
polynuclear rhenium-bismuth carbonyl complexes. Each of
the new rhenium-bismuth carbonyl complexes reported here
has been characterized by single-crystal X-ray diffraction
analyses and these represent the first examples of X-ray
crystallographic characterizations of rhenium-bismuth
bonding interactions.
Pyrolysis of 1 at 110 °C. A 15.5 mg portion of 1 was dissolved
in 15 mL of freshly distilled toluene and refluxed for 0.75 h after
which the solvent was removed in vacuo. The residue was
extracted in methylene chloride and separated by TLC using
4:1 hexane/methylene chloride (v/v) solvent mixture to give
products in order of elution, a colorless band of Re(Ph)(CO)5,
4, 2.4 mg (25% yield), a red band of Re2(CO)8(μ-BiPh)2, 5,
(0.5 mg, 4% yield), a yellow band of unreacted 1 1.0 mg and
a yellow band of 2 1.2 mg (8% yield). Spectral data for 5:
(νCO cm-1 in hexane): 2061(m), 2015(vs), 1972(s), 1969(m). 1H
NMR (400 MHz, CD2Cl2, 25 °C, TMS) δ = 7.3-7.8 (m, 10H,
Ph). Mass Spec. EI/MS m/z. 1168, Mþ, 1140, Mþ - CO. The
isotope distribution pattern is consistent with the presence of
two rhenium and two bismuth atoms.
Thermolysis of 2 at 125 °C. A 7.7 mg portion of 2 was
dissolved in 8 mL of freshly distilled octane and refluxed for
40 min. After cooling, the solvent was then removed in vacuo,
and the residue was extracted in methylene chloride and sepa-
rated by TLC by using 4:1 hexane/methylene chloride (v/v)
solvent mixture. This separation yielded a trace band of 1 (≈3%)
and a yellow band 2.8 mg consisting of a mixture of two isomers
cis-Re4(CO)16(μ-BiPh2)2(μ4-BiPhBiPh), cis-6 and trans-Re4-
(CO)16(μ-BiPh2)2(μ4-BiPhBiPh), trans-7 in a combined yield
39%. All attempts to isolate cis-6 and trans-7 in pure forms
chromatographically were unsuccessful. Crystals of the mixture
of isomers were obtained by slow evaporation of solvent from a
solution of the mixture in a methylene chloride/hexane solvent
mixture at -25 °C. The only way to obtain cis-6 and trans-7 in
pure forms was by physically separating the elongated rods of
yellow cis-6 from the block-shaped crystals of yellow trans-7.
Spectral data for cis-6: (νCO cm-1 in hexane): 2075(s), 2071(s),
2010(vs), 2003(m), 1996(s), 1972(m), 1958(s). 1H NMR (400 MHz,
CD2Cl2, rt, TMS) δ=6.7-7.8 (m, 30H, Ph). Mass Spec. EI/MS
m/z. 2492, Mþ, 2415, Mþ - Ph, 2116, Mþ - Re(CO)4Ph. The
isotope distribution pattern is consistent with the presence of
four rhenium and four bismuth atoms. Spectral data for trans-7:
IR (νCO cm-1 in hexane): 2075(s), 2072(s), 2009(vs), 2005(s),
1996(m), 1984(w), 1977(w), 1971(m), 1958(vs). 1H NMR (400 MHz,
CD2Cl2, rt, TMS) δ=6.9-7.8 (m., 30H, Ph). Mass Spec. EI/MS
m/z. 2492, Mþ, 2415, Mþ - Ph, 2116, Mþ - Re(CO)4Ph. The
isotope distribution pattern is consistent with the presence of
four rhenium and four bismuth atoms.
Experimental Section
General Data. All the reactions were performed under a
nitrogen atmosphere using the standard Schlenk techniques,
unless otherwise stated. Once they were formed, all of the
products were air stable, and they were isolated, stored, and
spectroscopically analyzed in air. Reagent grade solvents were
dried by the standard procedures and were freshly distilled prior
to use. Infrared spectra were recorded on an AVATAR 360 FT-
1
IR spectrophotometer. H NMR spectra were recorded on a
Varian Mercury 400 spectrometer operating at 399 MHz. Mass
spectrometric measurements performed by direct exposure
probe using electron impact ionization (EI) were made on a
VG 70S instrument. Triphenylbismuth (BiPh3) was purchased
from STREM and was used without further purification. Re2-
(CO)8[μ-η2-C(H)dC(H)Bun](μ-H) was prepared according to a
previously published procedure.9 Product separations were
˚
performed by TLC in air on Analtech 0.25 mm silica gel 60 A
F254 glass plates.
Reaction of BiPh3 with Re2(CO)8[μ-η2-C(H)dC(H)Bun](μ-H).
A 141.3 mg portion (0.321 mmol) of BiPh3 was added to 68.1 mg
(0.0999 mmol) of Re2(CO)8[μ-η2-C(H)dC(H)Bun](μ-H) in 20 mL
of heptane. The reaction was heated to reflux (97 °C) for 2.5 h.
After cooling, the solvent was removed in vacuo, and the
product was then isolated by TLC using a 4:1 hexane/methylene
chloride solvent mixture. The products listed in order of elution
include a yellow band of Re2(CO)8(μ-BiPh2)2, 1, 16.9 mg (13%
yield), a yellow band of [Re(CO)4(μ-BiPh2)]3, 2, 6.2 mg (5%
yield), and a yellow band of Re2(η6-C6H5Ph)(CO)7, 3, 4.7 mg
(7% yield). Spectral data for 1: IR (νCO cm-1 in hexane):
2064(s), 1990(vs), 1960(s). 1H NMR (300 MHz, CD2Cl2, rt,
TMS) δ=7.3-7.6 (m, 20H, Ph). Mass Spec. EI/MS m/z. 1322,
Mþ, 1245, Mþ -Ph, 1217, Mþ -(Ph þ CO). The isotope dis-
tribution pattern is consistent with the presence of two rhenium
and two bismuth atoms. Spectral data for 2: IR (νCO cm-1 in
hexane): 2076(m), 2072(m), 2005(vs), 1993(w), 1986(w),
Synthesis of Re4(CO)16(μ-BiPh2)2(μ-BiBiPh2), 8. A 21.1 mg
portion of a mixture 6 and 7 was dissolved in 10 mL of toluene
and photolyzed by using a 120 W sunlight lamp at room
temperature for 23 h. The solvent was then removed in vacuo,
and the residue was extracted in methylene chloride and sepa-
rated by TLC using 6:1 hexane/THF (v/v) solvent mixture to
yield the following products in order of elution: a yellow band
of 2 (0.5 mg, 2% yield), a yellow band as a mixture of the star-
ting compounds 6 and 7 (1.2 mg, 6% yield), and a red band of
8 (1.1 mg, 5% yield). Spectral data for Re4(CO)16(μ-BiPh2)2-
(μ-BiBiPh2), 8: IR(νCO in hexane): 2088 (w), 2075(s), 2062(vs),
1
1979(w), 1969(s). H NMR (300 MHz, CD2Cl2, rt, TMS) δ =
6.7-7.8 (m, 30H, Ph). Elemental analysis (%) calcd: 29.05, C;
1.52, H. Found: 28.48 C; 1.72, H. Spectral data for 3: IR (νCO
cm-1 in hexane): 2093(m), 2120(w), 1981(vs), 1961(s), 1949(w),
2001(vs), 1999(vs), 1980(m), 1970(m), 1958(s), 1954(s) cm-1
.
1H NMR (400 MHz, CD2Cl2, rt, TMS) δ = 7.3-7.6 (m,
30H, Ph). Mass Spec. EI/MS m/z. 2492, Mþ, 2415, Mþ - Ph,
2116, Mþ - RePh(CO)5. The isotope distribution pattern is
consistent with the presence of four rhenium and four bismuth
atoms.
1
1911(w). H NMR (400 MHz, CD2Cl2, rt, TMS) δ = 7.3-7.5
(m, 5H, Ph) 5.8 (d, 2H, Ph), 5.7 (t, 2H, Ph) and 5.4(t, 1H, Ph).
Mass Spec. EI/MS m/z. 722, Mþ, 694, Mþ - CO, 666, Mþ
-
2COs, 638, Mþ - 3COs, and 610, Mþ - 4COs. The isotope
distribution pattern is consistent with the presence of two
rhenium atoms.
Crystallographic Structural Analyses. Single crystals of yellow
1 and red 5 suitable for X-ray diffraction analysis were obtained
in glass vials exposed to air by slow evaporation of solvent from
solutions in methylene chloride/hexane solvent at -25 °C.
Yellow single crystals of 2 suitable for X-ray diffraction were
obtained in glass vials exposed to air by slow evaporation of
solvent from solutions in benzene/octane solvent mixtures at
room temperature. Yellow single crystals of 3 suitable for X-ray
diffraction analysis were obtained by cooling a solution in a
CH3OH/hexane solvent mixture to -25 °C. Yellow crystals
(7) (a) Ould-Ely, T.; Thurston, J. H.; Whitmire, K. H. Compt. Rend.
Chim. 2005, 8, 1906–1921. (b) Thurston, J. H.; Ould-Ely, T.; Trahan, D.;
Whitmire, K. H. Chem. Mater. 2003, 15, 4407–4416.
(8) (a) Whitmire, K. H. J. Cluster Sci. 1991, 2, 231–258. (b) Dikarev, E. V.;
Zhang, H.; Bo, L. J. Am. Chem. Soc. 2005, 127, 6156–6157. (c) Dikarev, E. V.;
Gray, T. G.; Bo, L. Angew. Chem., Int. Ed. 2005, 44, 1721–1724.
(9) Nubel, P. O.; Brown, T. L. J. Am. Chem. Soc. 1984, 106, 644–652.

Article
Inorganic Chemistry, Vol. 48, No. 19, 2009 9521
Table 1. Crystallographic Data for Compounds 1-3, 5, cis-6, trans-7, and 8
1
2
3
empirical formula
formula weight
crystal system
Re2Bi2O8C32H20
1322.84
monoclinic
Re3Bi3O12C48H30
1984.26
monoclinic
Re2O7C19H10
722.67
monoclinic
lattice parameters
˚
˚
b (A)
˚
c (A)
a (A)
12.8389(6)
9.6958(5)
14.4207(7)
90
110.265(1)
90
11.9528(5)
14.1317(5)
15.0482(6)
90
95.070(1)
90
29.1391(10)
11.8010(4)
12.2111(4)
90
111.757(1)
90
R (deg)
β (deg)
γ (deg)
3
˚
V (A )
space group
1684.02(14)
P21/n
2531.90(17)
P21
3899.9(2)
C2/c
Z
F
2
2.609
17.629
294(2)
56.62
2
2.603
17.588
294(2)
56.68
8
2.462
12.442
294(2)
56.54
calc (g/cm3)
μ (Mo KR) (mm-1
Temperature (K)
2Θ max (deg)
)
No. Obs. (I>2σ(I))
no. parameters
3781
200
10657
595
4834
253
goodness of fit (GOF)
max. shift in cycle
residualsa: R1; wR2
absor. corr, max/min
1.029
0.001
0.0303; 0.0779
1.000/0.216
1.52
0.983
0.001
0.0369; 0.0627
1.000/0.505
1.65
1.007
0.002
0.0265; 0.0631
1.000/0.298
1.21
-
3
˚
largest peak in final diff. map (e /A )
5
cis-6
trans-7
8
empirical formula
formula weight
crystal system
Re2Bi2C20O8H10
1168.64
monoclinic
Re4Bi4C64O16H42 C6H6
3
Re4Bi4C64O16H42 2C6H6
3
Re4Bi4C52O16H30
2491.48
triclinic
2569.59
monoclinic
2647.70
triclinic
lattice parameters
˚
˚
b (A)
˚
c (A)
a (A)
17.901(5)
14.229(4)
9.425(3)
90.00
90.148(5)
90.00
13.6304(4)
11.7873(4)
39.9265(13)
90.00
99.320(1)
90.00
9.8726(7)
11.2785(8)
16.2085(11)
80.065(1)
86.825(2)
69.451(1)
1664.6(2)
P1
12.1070(6)
13.2705(6)
18.6243(9)
80.985(1)
82.354(1)
81.817(1)
2906.4(2)
P1
R (deg)
β (deg)
γ (deg)
3
˚
V (A )
space group
2400.8(11)
P21/c
6330.1(4)
P21/n
Z
F
4
3.233
24.708
294(2)
52.74
4908
289
0.984
0.000
4
2.696
18.755
294(2)
56.68
8471
739
0.971
0.001
1
2.641
17.835
150(2)
56.68
7324
397
1.017
0.003
2
2.847
20.419
294(2)
56.62
9671
685
0.935
0.001
calc (g/cm3)
μ (Mo KR) (mm-1
temperature (K)
2Θmax (deg)
)
no. obs. (I>2σ(I))
no. parameters
goodness of fit (GOF)
max. shift in cycle
residualsa: R1; wR2
absor. corr, max/min
largest peak in final diff. map (e /A )
0.0748; 0.1743
1.000/0.0599
3.56
0.0529; 0.0925
1.000/0.165
1.37
0.0259; 0.0573
1.000/0.307
1.50
0.0497; 0.1004
1.000/0.498
2.45
-
3
˚
P
P
P
P
P
a R1 = hkl(||Fobs| - |Fcalc||)/ hkl|Fobs|; wR2 = [ hklw(|Fobs| - |Fcalc|)2/ hklwFobs
]
2 1/2, w = 1/σ2(Fobs); GOF = [ hklw(|Fobs| - |Fcalc|)2/(ndata
-
nvari)]1/2
.
of cis-6 and yellow trans-7 suitable for X-ray diffraction were
obtained together by slow evaporation of solvent in a glass vial
exposed to air from a solution of a mixture of the two com-
pounds in benzene/octane solvent at room temperature. The
yellow rod shaped crystals of cis-6 were physically separated
from the yellow block shaped crystals of trans-7 by examination
under a microscope. Compound 8 was crystallized by slow
evaporation of solvent in a glass vial exposed to air from a
solution in acetonitrile/octane at 25 °C. Red crystals of 8 were
also formed together with crystals of 6 and 7 when solutions of 6
and 7 were simply recrystallized in the presence of room light.
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 KR radiation
˚
(λ =0.71073 A). The raw data frames were integrated with the
SAINTþ program by using a narrow-frame integration algo-
rithm.10 Corrections for Lorentz and polarization effects were
also applied with SAINTþ. An empirical absorption correction
based on the multiple measurement of equivalent reflections was
applied for each analysis by using the program SADABS. 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.11 All
non-hydrogen atoms were refined with anisotropic thermal
parameters. Hydrogen atoms were placed in geometrically
idealized positions and included as standard riding atoms
(10) SAINTþ, Version 6.2a; Bruker Analytical X-ray System, Inc.: Madison,
(11) Sheldrick, G. M., SHELXTL, Version 6.1; Bruker Analytical X-ray
Systems, Inc.: Madison, WI, 1997.
WI, 2001.

9522 Inorganic Chemistry, Vol. 48, No. 19, 2009
Adams and Pearl
Figure 1. ORTEP diagram of the molecular structure of Re2(CO)8-
(μ-BiPh2)2, 1 showing 30% probability thermal ellipsoids. Selected bond
Figure 2. ORTEP diagram of the molecular structure of [Re(CO)4-
(μ-BiPh2)]3, 2 showing 30% probability thermal ellipsoids. Selected bond
distances (A) and angles (deg) are as follows: Re(1)-Bi(3) = 2.8391(5),
Re(1)-Bi(1) = 2.8554(6), Re(2)-Bi(2) = 2.8559(6), Re(2)-Bi(1) =
2.8583(5), Re(3)-Bi(2)=2.8499(6), Re(3)-Bi(3)=2.8521(5); Bi(3)-Re-
(1)-Bi(1)=89.704(16), Bi(2)-Re(2)-Bi(1)=94.531(16), Bi(2)-Re(3)-
Bi(3)=92.371(15), Re(1)-Bi(1)-Re(2)=134.895(18), Re(3)-Bi(2)-Re-
(2)=127.911(17), Re(1)-Bi(3)-Re(3)=131.792(18).
˚
distances (A) and angles (deg) are as follows: Re(1)-Bi(1) = 2.8403(3),
˚
Re(1*)-Bi(1)=2.8422(3), Re(1) Re(1*)=4.483(1); Bi(1)-Re(1)-Bi-
3 3 3
(10)=75.840(8), Re(1)-Bi(1)-Re(1*)=104.160(8).
during the least-squares refinements. Crystal data, data collec-
tion parameters, and results of the refinements are listed in
Table 1. Compound 5 crystallized in the monoclinic crystal
system with a β-angle very close to 90°, 90.148(5)o. Efforts to
obtain a satisfactory structural analysis in an orthorhombic
space group were unsuccessful; however, a satisfactory solution
and refinement was obtained in the monoclinic crystal system by
using the space group P21/c. Interestingly, the asymmetric
crystal unit contains two independent half formula equivalents
of the complex centered upon crystallographic centers of sym-
metry.
analyses of any compounds containing Re-Bi bonds. How-
ever, the compound ClBi[Re(CO)5]2 was analyzed by EX-
˚
AFS and a Re-Bi bond distance of 3.140(4) A was reported
which is considerably longer than any of the Re-Bi bond
distances that we have observed for the compounds reported
here.12
An ORTEP diagram of the molecular structure of 2 is
shown in Figure 2. The molecule contains a puckered six-
membered ring of three Re(CO)4 groups and three bridging
BiPh2 ligands arranged in an alternating fashion. The ring
exhibits a twist-boat conformation. The Re-Bi distances are
Results
Two new rhenium-bismuth carbonyl complexes Re2-
(CO)8(μ-BiPh2)2, 1, (13% yield) and [Re(CO)4(μ-BiPh2)]3, 2,
6.2 mg (5% yield) were obtained from the reaction of Re2-
(CO)8[μ-η2-C(H)dC(H)Bun](μ-H) with BiPh3 in heptane
solvent at reflux for 2.5 h. A new nonbismuth containing
compound Re2(η6-C6H5Ph)(CO)7, 3, was also obtained in
7% yield, eq 7.
˚
similar to those in 1, Re(1)-Bi(3)=2.8391(5) A, Re(1)-Bi(1)=
˚
˚
˚
˚
2.8554(6) A, Re(2)-Bi(2) = 2.8559(6) A, Re(2)-Bi(1) =
2.8583(5) A, Re(3)-Bi(2) = 2.8499(6) A, Re(3)-Bi(3) =
˚
2.8521(5) A. The internal ring angles at the rhenium atoms
are close to 90° to accommodate their octahedral-like six-
coordinate geometry, Bi(3)-Re(1)-Bi(1)=89.704(16)o, Bi-
(2)-Re(2)-Bi(1) = 94.531(16)o, Bi(2)-Re(3)-Bi(3) =
92.371(15)o. Although they are only tetra-coordinate, the
internal ring angles at the bismuth atoms are much larger
than the tetrahedral angle 109.5°: Re(1)-Bi(1)-Re(2) =
134.895(18)o, Re(3)-Bi(2)-Re(2) = 127.911(17)o, Re(1)-
Bi(3)-Re(3) = 131.792(18)o, presumably to offset the much
smaller angles at the rhenium atoms. As in 1 each rhenium in
2 has an 18-electron configuration.
An ORTEP diagram of the molecular structure of 3 is
shown inFigure 3. The molecule contains two rhenium atoms
with seven linear terminal carbonyl ligands distributed in a
5/2 ratio between the two metal atoms. The molecule also
contains a biphenyl ligand in which one of the phenyl rings is
η6-coordinated to one of the rhenium atoms. The molecule
can be compared to Re2(CO)10 in which three of the CO
ligandson oneof themetal atoms hasbeenreplaced by the η6-
C6H5Ph ligand. Like Re2(CO)10 compound 3 must contain a
All three products were characterized by single crystal
X-ray diffraction analyses. An Oak Ridge thermal ellipsoid
plot (ORTEP) diagram of the molecular structure of 1 is
shown in Figure 1. The molecule is crystallographically
centrosymmetrical in the solid state. There are two Re(CO)4
groups that are joined by two bridging BiPh2 ligands. The
Re2Bi2 unit is planar. Each bridging BiPh2 ligand donates a
total of 3-electrons to the rhenium atoms. As a result, each
rhenium atom achieves an 18-electron configuration without
the need for a metal-metal bond. The observed Re-Re
˚
distance is very long, 4.483(1) A, and is consistent with the
absence of any direct Re-Re bonding interaction. The two
independent Re-Bi bonding distances are Re(1)-Bi(1) =
(12) Compton, N. A.; Errington, R. J.; Fisher, G. A.; Norman, N. C.;
Webster, P. M.; Jarrett, P. S.; Nicholls, S. J.; Orpen, A. G.; Stratford, S. E.;
Williams, N. A. L. J. Chem. Soc., Dalton Trans. 1991, 669–676.
˚
˚
2.8403(3) A and Re(1*)-Bi(1)=2.8422(3) A. We are unable to
find any previous reports of single-crystal X-ray diffraction

Article
Inorganic Chemistry, Vol. 48, No. 19, 2009 9523
Figure 3. ORTEP diagram of the molecular structure of Re2(η6-C6H5-
Ph)(CO)7, 3, showing 30% probability thermal ellipsoids. Selected bond
˚
distances (A) are as follows: Re(1)-Re(2) = 2.9978(3), Re(2)-C(26) =
2.231(5), Re(2)-C(25) = 2.250(5), Re(2)-C(27) = 2.312(6), Re(2)-
C(28)=2.321(5), Re(2)-C(29)=2.323(5), Re(2)-C(24)=2.344(4).
Figure 4. ORTEP diagram of the molecular structure of Re2(CO)8-
(μ-BiPh)2, 5 showing 30% probability thermal ellipsoids. Selected bond
distances (A) and angles (deg) are as follows: (Molecule 1) Re(1)-Bi(1)=
2.8649(14), Re(1)-Bi(1*) = 2.9143(16), Re(1)-Re(1*)=3.1006(18),
(Molecule 2) Re(2)-Bi(2) = 2.8696(14), Re(2)-Bi(2*)=2.9047(16),
Re(2)-Re(2*) = 3.0946(19); (Molecule 1) Bi(1)-Re(1)-Bi(1*) =
115.11(4), Re(1)-Bi(1)-Re(1*) = 64.89(4), (Molecule 2) Bi(2)-Re-
(2)-Bi(2*)=115.19(4), Re(2)-Bi(2)-Re(2*)=64.81(4).
˚
Re-Re single bond in order for the metal atoms to achieve 18
electron configurations. Interestingly, the Re-Re bond dis-
˚
tance in 3, Re(1)-Re(2)=2.9978(3) A, is slightly shorter
13
˚
than that in Re2(CO)10 is 3.042(1) A.
When 1 was heated to 110 °C for 45 min, it was converted
to 2 (8% yield), the known compound Re(CO)5Ph,14 4 (25%
yield) and the new compound Re2(CO)8(μ-BiPh)2, 5 (4%
yield), eq 8. In eq 8 and all subsequent equations, all CO
ligands will be represented simply as lines attached to the
symbol for the rhenium atom.
˚
˚
2.8696(14) A, Re(2)-Bi(2*)=2.9047(16) A]. The phenyl
rings on the two bridging BiPh ligands exhibit a trans-
stereochemistry in both molecules. The intramolecular
˚
˚
Bi-Bi distances in 5, 4.877(1) A [4.875(1) A], are too long
for a direct bonding interaction in this molecule. Bridging
BiPh ligands were reported for the complex Fe2(CO)8-
(μ-BiPh)2, but in this molecule there is no metal-metal
bond.15
When a solution of compound 2 in octane solvent was
refluxed for 40 min, two new compounds were formed and
isolated as a mixture of isomers: cis-Re4(CO)16(μ-BiPh2)2-
(μ4-BiPhBiPh), cis-6 and trans-Re4(CO)16(μ-BiPh2)2(μ4-Bi-
PhBiPh), trans-7 in a combined yield of 39%, together with a
trace of 1 (≈3%), see eq 9.
1
Compound 5 was characterized by IR, H NMR, mass
spectroscopy, and by single-crystal X-ray diffraction
analysis. In the solid state compound 5 contains two
crystallographically independent centrosymmetrical mo-
lecules. Both molecules are structurally similar. An OR-
TEP diagram of the molecular structure of one of the two
molecules of 5 is shown in Figure 4. Compound 5 is
somewhat similar to 1 in that it contains two Re(CO)4
groups bridged by two phenylbismuth ligands, but in 5
the bridging bismuth ligands contain only one phenyl
group. As a result, each BiPh ligand serves only as a 2-
electron donor to the rhenium atoms, and a Re-Re single
bond is required in order for the metal atoms to achieve 18
electron configurations. The presence of the Re-Re
single bond was confirmed by the short interatomic
All attempts to isolate cis-6 and trans-7 in pure forms
chromatographically were unsuccessful; however, crys-
tals of the pure compounds could be obtained by recrys-
tallization of the mixtures and then physically separating
the elongated yellow rods of cis-6 from the block-shaped
crystals of yellow trans-7. To make things even more
difficult the IR spectra of the two compounds are vir-
tually identical. The reported IR spectra of these com-
pounds were obtained by dissolving the data crystals from
the crystal structure analyses.
An ORTEP diagram of the molecular structure of cis-6 is
shown in Figure 5. Compound cis-6 contains two Re2Bi3
rings that have a Bi2Ph2 ligand in common. Overall, the
molecule contains four Re(CO)4 groups, two bridging BiPh2
ligands and one quadruply bridging Bi(Ph)BiPh ligand. Each
˚
Re-Re distance, Re(1)-Re(1*) = 3.1006(18) A [molecule
˚
˚
2, Re(2)-Re(2*) = 3.0946(19) A], which is over 1.38 A
shorter than the Re-Re distance in 1, but is slightly
longer than that found in 3, 2.9978(3) A, and in Re2-
˚
(CO)10, 3.042(1) A.13 The Re-Bi bond distances in 5 are
˚
˚
similar to those in 1 and 2, Re(1)-Bi(1) = 2.8649(14) A,
˚
Re(1)-Bi(1*) =2.9143(16) A, [molecule 2, Re(2)-Bi(2) =
(13) Churchill, M. R.; Amoh, K. N.; Wasserman, H. J. Inorg. Chem. 1981,
20, 1609–1611.
(14) Webb, M. J.; Graham, W. A. G. J. Organomet. Chem. 1975, 93, 119–
127.
(15) Cassidy, J. M.; Whitmire, K. H. Inorg. Chem. 1991, 30, 2788–2795.

9524 Inorganic Chemistry, Vol. 48, No. 19, 2009
Adams and Pearl
Figure 6. ORTEP diagram of the molecular structure of trans-Re4-
(CO)16(μ-BiPh2)2[μ4-Bi(Ph)BiPh], trans-7 showing 30% probability ther-
˚
mal ellipsoids. Selected bonddistances (A) and angles (deg) are as follows:
Figure 5. ORTEP diagram of the molecular structure of cis-Re4(CO)16
-
Re(1)-Bi(2*) = 2.8213(3), Re(1)-Bi(1) = 2.8600(3), Re(2)-Bi(2) =
2.8256(3), Re(2)-Bi(1)=2.8561(3), Bi(2)-Re(1)=2.8213(3), Bi(2)-Bi-
(2*)=2.9765(3); Bi(1)-Re(1)-Bi(2*)=91.026(8), Bi(1)-Re(2)-Bi(2)=
88.904(8), Re(2)-Bi(1)-Re(1) = 124.802(9), Re(1)-Bi(2*)-Re(2*) =
129.314(8), Re(1)-Bi(2*)-Bi(2) = 111.309(11), Re(2)-Bi(2)-Bi(2*) =
106.780(9).
(μ-BiPh2)2[μ4-Bi(Ph)BiPh], cis-6 showing 30% probability thermal ellip-
˚
soids. Selected bond distances (A) and angles (deg) are as follows:
Bi(1)-Re(1) = 2.8485(7), Bi(1)-Re(2) = 2.8381(8), Bi(2)-Re(3) =
2.8240(7), Bi(2)-Re(2) = 2.8270(7), Bi(2)-Bi(3) = 3.0237(7), Bi(3)-
Re(1) = 2.8471(8), Bi(3)-Re(4) = 2.8511(7), Bi(4)-Re(4) = 2.8488(8),
Bi(4)-Re(3) = 2.8500(7); Re(2)-Bi(1)-Re(1) = 126.66(2), Re(3)-Bi-
(2)-Re(2) = 121.86(2), Re(3)-Bi(2)-Bi(3) = 110.01(2), Re(2)-Bi-
(2)-Bi(3) = 108.77(2), Re(1)-Bi(3)-Re(4) = 122.55(2), Re(1)-Bi(3)-
Bi(2)=110.17(2), Re(4)-Bi(3)-Bi(2)=111.14(2), Re(4)-Bi(4)-Re(3)=
128.99(2), Bi(3)-Re(1)-Bi(1)=92.77(2), Bi(2)-Re(2)-Bi(1)=91.26(2),
Bi(2)-Re(3)-Bi(4)=93.15(2), Bi(4)-Re(4)-Bi(3)=90.42(2).
steric interactions between the substituents on the two
bismuth atoms. In trans-7 the substituents on Bi(2) and
Bi(2*) have a staggered relationship while in cis-6, the
substituents have an eclipsed relationship. The most signifi-
cant difference between the molecular structures of trans-7
and cis-6 lies in the stereochemistry of the phenyl groups on
the bridging Bi(Ph)BiPh ligand; in trans-7 they are trans-
oriented while in cis-6, they are cis.
When solutions of the mixtures of cis-6 and trans-7 were
irradiated with visible light for 23 h or simply allowed to
stand for a period of days in room light, the new compound
Re4(CO)16(μ-BiPh2)2(μ-BiBiPh2), 8, was formed (5% yield).
Compound 8 is an isomer of both cis-6 and trans-7. An
ORTEP diagram of the molecular structure of 8 is shown in
Figure 7. As in cis-6 and trans-7, compound 8 contains two
Re(CO)4(μ-BiPh2)Re(CO)4 groups, but in 8 they are linked
by a bridging BiBiPh2 ligand to form a five-membered Re2Bi3
ring and a four-membered Re2Bi2 ring. Both rings share one
bismuth atom, Bi(2). The Re-Bi distances to the bridging
BiPh2 groups are similar to those in 1 and 2, Re(1)-Bi(1)=
BiPh2 ligand bridges a pair of Re(CO)4 groups. These Re-Bi
distances, Bi(1)-Re(2)=2.8381(8), Bi(1)-Re(1)=2.8485(7),
Bi(3)-Re(4) = 2.8511(7), Bi(4)-Re(4) = 2.8488(8), Bi(4)-
˚
Re(3)=2.8500(7) A, are similar to those in 1 and 2. The two
Ph2Bi[Re(CO)4]2 groups are linked by sharing a quadruply
bridging Bi(Ph)BiPh ligand to form the two fused five-
membered Re2Bi3 rings. Two rhenium atoms are bonded to
each bismuth atom of the Bi(Ph)BiPh ligand, Bi(2)-Re(3)=
˚
˚
2.8240(7) A, Bi(2)-Re(2) = 2.8270(7) A, Bi(3)-Re(1) =
˚
˚
2.8471(8) A, Bi(3)-Re(4) = 2.8511(7) A. The two bismuth
atoms are joined by a Bi-Bi single bond. The Bi-Bi bonding
˚
distance, Bi(2)-Bi(3) = 3.0237(7) A, is similar to the Bi-Bi
distance in the free molecule Bi2Ph4 which has Bi-Bi single
bond distances of 2.990(2) A and 2.988(1) A.16b A similar
doubly bridging Bi2[CH2C(CH3)3]2 ligand was found in the
complex W2(CO)8{η2-Bi2[CH2C(CH3)3]2}; the Bi-Bi dis-
16a
˚
˚
tance was 2.9799(7) A.17 The Bi-Bi distance in the tungsten
˚
˚
˚
2.8259(7) A, Re(2)-Bi(1) = 2.8423(7) A, Re(2)-Bi(2) =
complex W(CO)5{η2-Bi2[CH2C(CH3)3]2} was reported to be
˚
˚
2.9203(7) A, Re(3)-Bi(4)=2.8477(7) A, and Re(4)-Bi(4)=
2.8435(7) A. Atom Bi(2) has no phenyl substituents. It is
bonded to three rhenium atoms, Re(1)-Bi(2)=2.8931(7) A,
2.8769(5) A.17 The phenyl groups on the Bi2Ph2 ligand in cis-
˚
˚
6 have a cis- or syn-stereochemistry. The Bi2Ph2 ligand serves
as a 6-electron donor. Each bismuth atom donates 3-elec-
trons to two rhenium atoms, and as in 1, each rhenium atom
achieves an 18-electron configuration.
˚
˚
˚
Re(2)-Bi(2)=2.9203(7) A, Re(3)-Bi(2)=2.8595(6) A and
a BiPh2 group by a Bi-Bi single bond that is slightly longer
than the Bi-Bi bond distances in cis-6 and trans-7, Bi(2)-
An ORTEP diagram of the molecular structure of trans-7
is shown in Figure 6. This compound lies on a crystal-
lographic center of symmetry in the solid state. Compound
trans-7 is very similar to cis-6. It contains two Re2Bi3 rings
that are fused via a bridging Bi2Ph2 ligand. The Bi-Bi
˚
Bi(3) = 3.0824(7) A. Atom Bi(2) has distorted tetrahedral
geometry, Re(3)-Bi(2)-Re(1) = 116.84(2)o, Re(3)-Bi(2)-
Re(2) = 116.46(2)o, Re(1)-Bi(2)-Re(2) = 101.27(2)o, Re-
(3)-Bi(2)-Bi(3) = 101.702(19)o, Re(1)-Bi(2)-Bi(3) =
104.13(2)o, Re(2)-Bi(2)-Bi(3) = 116.43(2)o.
˚
distance is slightly shorter (0.05 A) than that in cis-6, Bi-
˚
(2)-Bi(2*) =2.9765(3)A. This could be due to decreased
Discussion
In recent studies we have obtained the dirhenium com-
pound Re2(CO)8(μ-SbPh2)2, 9, from the thermal decomposi-
tion of HRe(CO)4SbPh3 under hydrogen.6 Compound 1,
the bismuth homologue of 9, has now been obtained from
the reaction of Re2(CO)8[μ-η2-C(H)dC(H)Bun](μ-H) with
(16) (a) Calderazzo, F.; Poli, R.; Pellizi, G. J. Chem. Soc., Dalton Trans.
1984, 2365–2369. (b) Whitmire, K. H.; Cassidy, J. M. Acta Crystallogr., Sect. C:
Cryst. Struct. Commun. 1992, 48, 917–919.
(17) Balaz, G.; Balaz, L.; Breunig, H. J.; Lork, E. Organometallics 2003,
22, 2919–2924.
ꢀ
ꢀ

Article
Inorganic Chemistry, Vol. 48, No. 19, 2009 9525
Scheme 1
containing two coupled phenyl rings in the form of the
η6-coordinated biphenyl ligand can account for the fate of
some of these rings. The mechanism of the formation of 3 was
not established, but we can say our attempts to prepare it
independently by heating solutions of Re2(CO)8[μ-η2-C-
(H)dC(H)Bun](μ-H) with biphenyl did not yield any of it.
Interestingly, the compound 5 was obtained from 1 by loss of
two phenyl groups, and the phenyl containing compound 4
was obtained as a coproduct of this reaction. Compound 5
was the only one that we encountered in this study that
contained a Re-Re bond. The principal products obtained
from the thermolysis of 2 at 125 °C were the higher nuclearity
Re4Bi4 compounds cis-6 and trans-7. These products could
have been formed by the addition of a ReBi fragment, such as
A, to 2 itself followed by loss of two phenyl groups and the
formation of a Bi-Bi bond. Finally, it was observed that cis-6
and trans-7 are converted to 8 under the influence of visible
radiation which induces a shift of one of the phenyl rings on
the bridging Bi(Ph)BiPh ligand to the neighboring Bi atom
and a rhenium group is shifted from that Bi atom back to the
Bi atom from which the phenyl group was lost. This re-
arrangement has produced a novel BiBiPh2 ligand that serves
as a bridge to the four rhenium atoms. Compound 8 was
formed by a shift of one of the phenyl ligands on the bridging
Bi(Ph)BiPh ligand to the neighboring bismuth atom.
The transformation occurs in the light but not in the dark.
The mechanism has not been established, but if it occurs
by a 1,2 shift, it would be backside process in trans-7, and a
front process in cis-6, see Scheme 1. The phenyl shift would
have to be accompanied by a shift of one of the rhenium
atoms on the bismuth that receives the phenyl group to
the bismuth atom that lost the phenyl group. This shift of
the rhenium atom would convert one of the five-membered
rings in the cis-6 or trans-7 into the four-membered ring
found in 8.
Figure 7. ORTEP diagram of the molecular structure of Re4(CO)16
-
(μ-BiPh2)2(μ4-BiBiPh2), 8, showing 30% probability thermal ellipsoids.
˚
Selected bond distances (A) and angles (deg) are as follows: Re(1)-
Bi(1) = 2.8259(7), Re(1)-Bi(2) = 2.8931(7), Re(2)-Bi(1) = 2.8423(7),
Re(2)-Bi(2) = 2.9203(7), Re(3)-Bi(4) = 2.8477(7), Re(3)-Bi(2) =
2.8595(6), Re(4)-Bi(3) = 2.8337(7), Re(4)-Bi(4) = 2.8435(7), Bi(2)-
Bi(3)=3.0824(7); Bi(1)-Re(1)-Bi(2)=76.002(18), Bi(1)-Re(2)-Bi(2)=
75.322(18), Bi(4)-Re(3)-Bi(2)=95.92(2), Bi(3)-Re(4)-Bi(4)=85.66(2),
Re(1)-Bi(1)-Re(2) = 104.92(2), Re(3)-Bi(2)-Re(1) = 116.84(2), Re-
(3)-Bi(2)-Re(2) = 116.46(2), Re(1)-Bi(2)-Re(2) = 101.27(2), Re-
(3)-Bi(2)-Bi(3) = 101.702(19),
Re(1)-Bi(2)-Bi(3) = 104.13(2),
Re(2)-Bi(2)-Bi(3) = 116.43(2), Re(4)-Bi(3)-Bi(2) = 120.38(2), Re-
(3)-Bi(4)-Re(4)=127.67(2).
BiPh3. Small amounts of the compound 2, a cyclotrimer of
the unit Re(CO)4(BiPh2), was also obtained in this reaction.
Interestingly, small amounts of 2 were obtained from 1 and
also 1 from 2, when solutions of the pure compounds were
heated to temperatures greater than 100 °C. Such intercon-
version could be occuring by a fragmentation process invol-
ving the formation of small amounts of a monomeric unit
such as Re(CO)4(BiPh2), A, having a 16 electron configura-
tion at rhenium which might have no more than a fleeting
existence in very low concentrations, for example, eq 10. In
1964 Nesmeyanov et al. reported the synthesis of a similar 18
electron compound Re(CO)5(BiPh2) which was reported to
decompose in organic solvents.18
The facile cleavage of Bi-C bonds to the phenyl rings in
the reactions of BiPh3 with Re2(CO)8[μ-η2-C(H)dC(H)Bun]-
(μ-H) has yielded a range of interesting, new polynuclear
Re-Bi compounds that have provided the first examples of
Re-Bi bonding interactions to be characterized by single-
crystal X-ray diffraction analyses. It has already been shown
that 2 is a precursor to a new low temperature ammoxidation
catalyst.6 It seems likely that some of these new complexes
will also serve as precursors to other new catalysts upon
removal of their ligands.
Acknowledgment. This research was supported by the
USC NanoCenter and the National Science Foundation
under Grant CHE-0743190.
The formation of 1 and 2 requires the cleavage of phenyl
rings from the BiPh3 reagent. The formation of compound 3
Supporting Information Available: CIF files for each of the
structural analyses are available. This material is available free
of charge via the Internet at http://pubs.acs.org.
(18) Nesmeyanov, A. N.; Khandozh, V. N.; Kolobva, N. E.; Anismov, K.
N. Dokl. Akad. Nauk. SSSR 1964, 156, 383–385.