C-H versus C-C activation of biphenylene in its reactions with iron group carbonyl clusters

Article abstract of DOI:10.1021/om9800445

Co-thermolysis of biphenylene ((C₆H)₂) with Fe₃(CO)₁₂ or Fe₂(CO)₉ leads to activation of a biphenylene C-C bond to generate Fe₂(CO)₅(μ-CO)(μ-η²,η ⁴-(C₆H₄)₂) (1). Similar reaction with Ru₃(CO)₁₂ affords Ru₂(CO)₅(μ-CO)(μ-η²,η ⁴-(C₆H₄)₂) (2) and Ru₆(CO)₁₇(μ₆-C) (3), and the reaction with Os₃(CO)₁₂ affords Os₂(CO)₆(μ-η²,η⁴-(C ₆H₄)₂) (4) and Os₄(CO)₁₂(μ₄-η²-(C ₆H₃)Ph) (5). In contrast, treating biphenylene with Os₃(CO)₁₀(NCMe)₂ leads to C-H bond activation to give (μ-H)₂Os₃(CO)₉(μ₃-η ²-C₆H₂(C₆H₄)) (6). The new compounds have been characterized by elemental analyses and mass, IR, and NMR spectroscopy. The structures of 2, 4, and 5 were determined by an X-ray diffraction study. Compound 2 and 4 can be viewed to contain a metallacyclopentadienyl unit which binds the other metal atom in an η⁵-fashion. Compound 5 is the first butterfly cluster of the type Os₄(CO)₁₂(aryne).

Full text of DOI:10.1021/om9800445

Organometallics 1998, 17, 2477-2483
2477
C-H ver su s C-C Activa tion of Bip h en ylen e in Its
Rea ction s w ith Ir on Gr ou p Ca r bon yl Clu ster s
Wen-Yann Yeh* and Sodio C. N. Hsu
Department of Chemistry, National Sun Yat-Sen University, Kaohsiung, Taiwan 804
Shie-Ming Peng* and Gene-Hsiang Lee
Department of Chemistry, National Taiwan University, Taipei, Taiwan 107
Received J anuary 23, 1998
Co-thermolysis of biphenylene ((C6H4)2) with Fe3(CO)12 or Fe2(CO)9 leads to activation of
a biphenylene C-C bond to generate Fe2(CO)5(µ-CO)(µ-η2,η4-(C6H4)2) (1). Similar reaction
with Ru3(CO)12 affords Ru2(CO)5(µ-CO)(µ-η2,η4-(C6H4)2) (2) and Ru6(CO)17(µ6-C) (3), and the
reaction with Os3(CO)12 affords Os2(CO)6(µ-η2,η4-(C6H4)2) (4) and Os4(CO)12(µ4-η2-(C6H3)Ph)
(5). In contrast, treating biphenylene with Os3(CO)10(NCMe)2 leads to C-H bond activation
to give (µ-H)2Os3(CO)9(µ3-η2-C6H2(C6H4)) (6). The new compounds have been characterized
by elemental analyses and mass, IR, and NMR spectroscopy. The structures of 2, 4, and 5
were determined by an X-ray diffraction study. Compound 2 and 4 can be viewed to contain
a metallacyclopentadienyl unit which binds the other metal atom in an η5-fashion. Compound
5 is the first butterfly cluster of the type Os4(CO)12(aryne).
In tr od u ction
Four papers concerning activation of biphenylene by
mononuclear6-8 and binuclear9 metal complexes were
previously reported. However, the coordination chem-
istry of biphenylene with metal clusters has received
little attention. We have been interested in the sys-
tematic chemistry of small organic substrates bound to
transition-metal carbonyl clusters.10 Presented in this
work are reactions of M3(CO)12 (M ) Fe, Ru, and Os)
with biphenylene, leading to several new complexes
containing metallacycle and benzyne moieties.
The insertion of transition-metal atoms into a carbon-
carbon bond through oxidative addition is known for
many type of hydrocarbons, especially strained-ring
compounds and compounds which become aromatic on
C-C cleavage.1 The biphenylene ligand itself has been
known for many years.2 An X-ray diffraction study of
biphenylene suggests that the central ring of the
molecule has little delocalization.3 Theoretical calcula-
tions show that biphenylene has a relatively low reso-
nance energy of about 15 kcal/mol,4 while the strain
energy of the four-membered ring is high, about 63 kcal/
mol.5 This should facilitate formation of a metallacycle
when biphenylene is treated with a metal complex.
Exp er im en ta l Section
Gen er a l Meth od s. All manipulations were carried out
under an atmosphere of purified dinitrogen with standard
Schlenk techniques.11 Fe3(CO)12, Fe2(CO)9, and Ru3(CO)12 were
purchased from Strem and used as received. Os3(CO)12 was
prepared from OsO4 and CO by the literature method.12
Biphenylene was prepared by flash vacuum pyrolysis of
phthalic anhydride as described in the literature.13 Solvents
were dried over the appropriate reagents under dinitrogen and
(1) (a) Adams, D. M.; Chatt, J .; Guy, R. G.; Sheppard, N. J . Chem.
Soc. 1961, 738. (b) Bailey, N. A.; Gillard, R. D.; Keeton, M.; Mason,
R.; Russell, D. R. J . Chem. Soc., Chem. Commun. 1966, 396. (c)
McQuillin, F. J .; Powell, K. C. J . Chem. Soc., Dalton Trans. 1972, 2123.
(d) Barretta, A.; Cloke, F. G. N.; Feigenbaum, A.; Green, M. L. H.;
Gourdon, A.; Prout, K. J . Chem. Soc., Chem. Commun. 1981, 156. (e)
Barretta, A.; Chong, K. S.; Cloke, F. G. N.; Feigenbaum, A.; Green, M.
L. H. J . Chem. Soc., Dalton Trans. 1983, 861. (f) Flood, T. C.; Statler,
J . A. Organometallics 1984, 3, 1795. (g) Berris, B. C.; Hovakeemian,
G. H.; Lai, Y.-H.; Mestdagh, H.; Vollhardt, K. P. C. J . Am. Chem. Soc.
1985, 107, 5670. (h) Periana, A.; Bergman, R. G. J . Am. Chem. Soc.
1986, 108, 7346. (i) Schwager, H.; Spyroudis, S.; Vollhardt, K. P. C. J .
Organomet. Chem. 1990, 382, 191. (j) Lu, Z.; J un, C.-H.; de Gala, S.
R.; Sigalas, M.; Eisenstein, O.; Crabtree, R. H. J . Chem. Soc., Chem.
Commun. 1993, 1877. (k) Murakami, M.; Amii, H.; Shigeto, K.; Ito, Y.
J . Am. Chem. Soc. 1996, 118, 8285.
(2) (a) Cohen, S. G.; Massey, A. G. J . Organomet. Chem. 1967, 10,
471. (b) Gardner, S. A.; Gordon, H. B.; Rausch, M. D. J . Organomet.
Chem. 1973, 60, 179. (c) Uso´n, R.; Vicente, J .; Cirac, J . A.; Chicote, M.
T. J . Organomet. Chem. 1980, 198, 105. (d) Cornioley-Deuschel, C.;
von Zelewsky, A. Inorg. Chem. 1987, 26, 3354. (e) Becker, S.; Fort, Y.;
Vanderesse, R.; Caubere, P. J . Org. Chem. 1989, 54, 4848.
(3) (a) Mak, T. C. W.; Trotter, J . J . Chem. Soc. 1962, 1. (b) Toda, F.;
Garratt, P. Chem. Rev. 1992, 92, 1685.
(4) (a) Cass, R. C.; Springall, H. D.; Quincey, P. G. J . Chem. Soc.
1955, 1188. (b) Dewer, M. J . S. The Molecular Orbital Theory of
Organic Chemistry; McGraw-Hill: New York, 1969.
(5) Cava, M. P.; Mitchell, M. J . Cyclobutadienes and Related
Compounds; Academic Press: New York, 1967.
(6) Perthuisot, C.; J ones, W. D. J . Am. Chem. Soc. 1994, 116,
3647.
(7) Lu, Z.; J un, C.-H.; de Gala, S. R.; Sigalas, M.; Eisenstein, O.;
Crabtree, R. H. Organometallics 1995, 14, 1168.
(8) Eisch, J . J .; Piotrowski, A. M.; Han, K. I.; Kru¨ger, C.; Tsay, Y.
H. Organometallics 1985, 4, 224.
(9) Perthuisot, C.; Edelbach, B. L.; Zubris, D. L.; J ones, W. D.
Organometallics 1997, 16, 2016.
(10) (a) Yeh, W.-Y.; Chen, S,-L.; Peng, S.-M.; Lee, G.-H. J . Orga-
nomet. Chem. 1993, 461, 207. (b) Yeh, W.-Y.; Chen, S,-B.; Peng, S.-M.;
Lee, G.-H. J . Organomet. Chem. 1994, 481, 183. (c) Yeh, W.-Y.; Cheng,
Y.-J .; Chiang, M. Y. Organometallics 1997, 16, 918. (d) Hsu, M.-A.;
Yeh, W.-Y.; Chiang, M. Y. J . Organomet. Chem., in press.
(11) Shriver, D. F.; Drezdzon, M. A. The Manipulation of Air-
Sensitive Compounds, 2nd ed.; Wiley: New York, 1986.
(12) J ohnson, B. F. G.; Lewis, J . Inorg. Synth. 1972, 13, 92.
(13) Brown, R. F. C.; Gardner, D. V.; McOmie, J . F. W.; Solly, R. K.
Aust. J . Chem. 1967, 20, 139.
S0276-7333(98)00044-2 CCC: $15.00 © 1998 American Chemical Society
Publication on Web 05/15/1998

2478 Organometallics, Vol. 17, No. 12, 1998
Yeh et al.
distilled immediately before use. Preparative thin-layer chro-
matographic (TLC) plates were prepared from silica gel
(Merck). Infrared spectra were recorded with a 0.1 mm path
length CaF2 solution cell on a Hitachi I-2001 IR spectrometer.
1H and 13C NMR spectra were obtained on a Varian VXR-300
spectrometer at 300 and 75.4 MHz, respectively. Fast-atom
bombardment (FAB) and electron-impact (EI) mass spectra
were recorded by using a VG Blotch-5022 mass spectrometer.
Elemental analyses were performed at the National Science
Council Regional Instrumentation Center at National Chen-
Kung University, Tainan, Taiwan.
Rea ction of Bip h en ylen e w ith F e3(CO)12. A solution of
biphenylene (30 mg, 0.2 mmol) and Fe3(CO)12 (100 mg, 0.2
mmol) in n-heptane (20 mL) was heated to reflux under
dinitrogen for 3 h. The mixture was cooled to room temper-
ature, and the solvent was removed under vacuum. The
residue was subjected to TLC, eluting with n-hexane. Unre-
acted Fe3(CO)12 and biphenylene were recovered from the front
two bands. Isolation of material from the red-brown band
afforded the known Fe2(CO)5(µ-CO)(µ-η2,η4-(C6H4)2)14 (1) (28
mg, 0.06 mmol, 30%). IR (KBr, νCO): 2064 (m), 2024 (s), 1990
(s), 1974 (s), 1888 (m) cm-1. MS (EI): m/z 432 (M+, 56Fe), 432
- 28n (n ) 1-6). 1H NMR (CDCl3, 20 °C): δ 7.23-7.311 (m,
4H), 7.51 (d, J ) 8 Hz, 2H), 7.75 (d, J ) 8 Hz, 2H).
(4) (16 mg, 0.022 mmol, 23%). The third red band gave Os4-
(CO)12(µ4-η2-(C6H3)Ph) (5) (28 mg, 0.02 mmol, 30% based on
Os atom). The crystals of 4 and 5 found suitable for X-ray
diffraction study were each grown from a concentrated hexane
solution at -20 °C.
Ch a r a cter iza tion of 4. IR (n-hexane, νCO): 2084 (m),
2072 (sh), 2048 (s), 2004 (s), 1996 (s), 1974 (s) cm-1. MS (EI):
m/z 704 (M+, 192Os), 702 - 28n (n ) 1-6). 1H NMR (CDCl3,
20 °C): δ 7.06 (t, J ) 8 Hz, 2H), 7.38 (t, J ) 8 Hz, 2H), 8.05
(d, J ) 8 Hz, 2H), 8.37 (d, J ) 8 Hz, 2H).
Ch a r a cter iza tion of 5. IR (n-hexane, νCO): 2100 (w),
2076 (s), 2044 (vs), 2008 (s), 1998 (s), 1972 (m) cm-1
. MS
(EI): m/z 1256 (M+, 192Os), 1256 - 28n (n ) 1-12). 1H NMR
(CDCl3, 20 °C): δ 6.32 (d, J ) 9 Hz, 1H), 6.50 (d, J ) 9 Hz,
1H), 7.13 (s, 1H), 7.0-7.8 (m, 5H, Ph). Anal. Calcd for
C
24H8O12Os4: C, 23.08; H, 0.65. Found: C, 22.88; H, 0.87.
Rea ction of Bip h en ylen e w ith Os3(CO)10(NCMe)2.
A
mixture of biphenylene (33 mg, 0.2 mmol) and Os3(CO)10-
(NCMe)2 (40 mg, 0.043 mmol) was ground and placed in a
Teflon-sealed Schlenk tube under N2. The tube was placed in
an oil bath at 180 °C for 5 min and then cooled to ambient
temperature. The residue was extracted with dichloromethane
and subjected to TLC, with n-hexane as the eluant. (µ-H)2Os3-
(CO)9(µ3-η2-C6H2(C6H4)) (6) (15 mg, 0.015 mmol, 36%) was
isolated from the major yellow band. IR (n-hexane, νCO):
2112 (m), 2084 (s), 2060 (vs), 2032 (s), 2020 (sh), 2004 (vs),
1986 (s), 1974 (w) cm-1. MS (FAB): m/z 980 (M+, 192Os), 980
- 28n (n ) 1-9). 1H NMR (CDCl3, 20 °C): δ -18.99 (s, 2µ-
H), 7.04-6.94 (m, 4H), 7.02 (s, 2H).
Rea ction of Bip h en ylen e w ith F e2(CO)9. The reaction
of Fe2(CO)9 (80 mg, 0.22 mmol) with biphenylene (35 mg, 0.23
mmol) was carried out in refluxing cyclohexane solution (10
mL) for 5 h. Compound 1 (33 mg, 0.08 mmol) was obtained in
36% yield after purification by TLC.
Rea ction of Bip h en ylen e w ith Ru 3(CO)12. A solution of
biphenylene (28 mg, 0.18 mmol) and Ru3(CO)12 (115 mg, 0.18
mmol) in n-octane (20 mL) was heated to reflux for 4 h
under dinitrogen. The mixture was cooled to room tempera-
ture, and the solvent was removed under vacuum. The resi-
due was separated by TLC, eluting with n-hexane. Unreacted
Ru3(CO)12 and biphenylene were recovered from the front two
bands. The material from the orange band was the new
complex Ru2(CO)5(µ-CO)(µ-η2,η4-(C6H4)2) (2) (32 mg, 0.06 mmol,
33%). The last dark red band afforded the known Ru6(CO)17-
(µ6-C)15 (3) (26 mg, 0.02 mmol, 33% based on Ru atom). The
crystals of 2 found suitable for X-ray diffraction study were
grown from a concentrated hexane solution at -20 °C.
Ch a r a cter iza tion of 2. IR (n-hexane, νCO): 2092 (m),
X-r a y Cr ysta llogr a p h y. A dark orange crystal of Ru2-
(CO)5(µ-CO)(µ-η2,η4-(C6H4)2) (2, ca. 0.20 × 0.25 × 0.35 mm), a
yellow crystal of Os2(CO)6(µ-η2,η4-(C6H4)2) (4, ca. 0.20 × 0.20
× 0.10 mm), and a dark red crystal of Os4(CO)12(µ4-η2-(C6H3)-
Ph) (5, ca. 0.30 × 0.20 × 0.40 mm) were each mounted in a
thin-walled glass capillary and aligned on the Nonius CAD-4
diffractometer with graphite-monochromated Mo KR radiation
(λ ) 0.710 73 Å). Lattice parameters were determined from
25 randomly selected reflections with 2θ ranging from 23.14°
to 25.86° (compound 2), from 15.12° to 24.42° (compound 4),
and from 15.00° to 30.40° (compound 5). The data were
collected at 298 K using the θ/2θ scan technique to maximum
2θ values of 50.0° for 2, 4, and 5. A scan of 2(0.65 + 0.35 tan
θ)° at a variable speed of 2.06-8.24°/min for 2 and 4 and 2(0.90
+ 0.35 tan θ)° at a variable speed of 3.30-8.24°/min for 5 was
performed. The intensities of three representative reflections,
which were measured every 60 min of X-ray exposure time,
remained constant throughout data collection, so no decay
correction was applied. All data were corrected for Lorentz
and polarization effects and for the effects of absorption. The
structures were solved by the direct method and refined by
least-squares cycles.16 The non-hydrogen atoms were refined
anisotropically. Hydrogen atoms were included but not re-
fined. All calculations were performed using the NRCSDP-
VAX package. A summary of relevant crystallographic data
for 2, 4, and 5 is provided in Table 1.
2032 (vs), 2020 (s), 1980 (m), 1882 (m, µ-CO) cm-1
. MS
(FAB): m/z 524 (M+, 102Ru), 523 - 28n (n ) 1-6). 1H NMR
(CDCl3, 20 °C): δ 7.13 (t, J ) 8 Hz, 2H), 7.56 (t, J ) 8 Hz,
2H), 7.91 (d, J ) 8 Hz, 2H), 8.34 (d, J ) 8 Hz, 2H). 13C{1H}
NMR (CDCl3, 20 °C): δ 125.5 (s), 126.0 (s), 129.9 (s), 132.4
(s), 136.7 (s), 151.6 (s), 188.9 (s, CO). Anal. Calcd for C18H8O6-
Ru2: C, 41.39; H, 1.54. Found: C, 40.84; H, 1.88.
Ch a r a cter iza tion of 3. IR (n-hexane, νCO): 2068(s), 2049
(s), 2010 (sh), 1998(w), 1958 (w), 1854 (w, br) cm-1. MS (EI):
m/z 1094 (M+, 102Ru) and successive loss of CO. The IR data
match the literature values for the compound.15
Rea ction of Bip h en ylen e w ith Os3(CO)12. Biphenylene
(90 mg, 0.59 mmol), Os3(CO)12 (90 mg, 0.10 mmol), and
n-decane (1 mL) were mixed in a Teflon-sealed Schlenk tube
under dinitrogen. The tube was placed in an oil bath at 200
°C for 15 h. After cooling to ambient temperature, the brown-
red residue was extracted with n-hexane (3 × 10 mL) to give
a red-brown solution. Unreacted Os3(CO)12 (30 mg, 33%) was
recovered from the insoluble solids. The extractant was
concentrated to ca. 5 mL on a rotary evaporator and separated
by TLC with n-hexane as the eluant. Unreacted biphenylene
was recovered from the first pale yellow band. The material
Resu lts a n d Discu ssion
Syn th eses. Treatment of biphenylene with Fe3-
(CO)12 in refluxing heptane (98 °C) for 3 h and subse-
quent workup by TLC produces Fe2(CO)5(µ-CO)(µ-η2,η4-
(C6H4)2)14 (1), in which one iron atom has inserted into
the central carbon-carbon bond of biphenylene, forming
a metallacyclopentadienyl moiety, and the cluster nu-
clearity has changed from 3 to 2. Biphenylene reacts
with Fe2(CO)9 also leading to 1 as the major metal-
containing product (eq 1).
from the second yellow band afforded Os2(CO)6(µ-η2,η4-(C6H4)2
)
(14) Singh, K.; McWhinnie, W. R.; Chen, H. L.; Sun, M.; Hamor, T.
A. J . Chem. Soc., Dalton Trans. 1996, 1545.
(15) (a) J ohnson, B. F. G.; J ohnson, R. D.; Lewis, J . J . Chem. Soc.,
Chem. Commun. 1967, 1057. (b) J ohnson, B. F. G.; J ohnson, R. D.;
Lewis, J . J . Chem. Soc. A 1968, 2865.
(16) SIR92: Altomare, A.; Cascarano, M.; Giacovazzo, C.; Guagliardi,
A. J . Appl. Crystallogr. 1993, 26, 343.

Reactions of Biphenylene with Fe Group Clusters
Organometallics, Vol. 17, No. 12, 1998 2479
Ta ble 1. Cr ysta llogr a p h ic Da ta for
Ru 2(CO)5(µ-Co)(µ-η2,η4-(C6H4)2) (2),
Os2(CO)6(µ-η2,η4-(C6H4)2) (4), a n d
Os4(CO)12(µ4-η2-(C6H3)P h ) (5)
2
4
5
chem formula
cryst syst
space group
fw
a, Å
b, Å
C
18H8O6Ru2
C18H8O6Os2
triclinic
P1h
C24H8O12Os4
triclinic
P1h
1249.11
9.253(4)
10.872(2)
13.534(3)
monoclinic
P21/c
522.39
The reaction of biphenylene and Ru3(CO)12 is carried
out in refluxing octane (126 °C), giving Ru2(CO)5(µ-CO)-
(µ-η2,η4-(C6H4)2) (2) and the known carbide cluster Ru6-
(CO)17(µ6-C) (3) (eq 2). Complex 3 was previously
700.65
8.254(6)
8.767(1)
12.841(3)
85.78(2)
102.41(3)
85.77(3)
867.7(7)
2
2.682
146.759
0.035
0.037
1.73
13.227(3)
10.104(3)
13.503(1)
95.298(17)
106.51(1)
104.57(3)
1730.3(7)
4
2.005
17.430
0.023
0.021
c, Å
R, deg
â, deg
γ, deg
V, Å3
80.70(3)
1337.3(7)
2
Z
D
calc, g cm-3
3.102
190.255
0.060
0.065
2.94
µ, cm-1
Ra
a
Rw
GOF
2.21
a
2
R ) ∑||Fo| - |Fc||/∑ |Fo|; Rw ) {∑[ω(|Fo| - |Fc|)2]/∑ω|Fo| ]}1/2
.
tial to activate biphenylene, as the 16-electron mono-
nuclear metal fragment is known to cleave arene C-H
bonds.18
It is of interest to compare the reaction of biphenylene
with the more labile cluster Os3(CO)10(NCMe)2,19 while
a dihydrido benzyne complex (µ-H)2Os3(CO)9(µ3-η2-C6H2-
(C6H4)) (6) is obtained (eq 4). In this reaction, two
prepared by Lewis and co-workers from thermolysis of
Ru3(CO)12 in hydrocarbon solvents.15 The source of the
carbide carbon in 3 is unknown.
In contrast, the analogous reaction with Os3(CO)12 re-
quires harsher conditions, in which Os3(CO)12, biphen-
ylene (5-fold), and 1 mL of decane are mixed in a Teflon-
sealed Schlenk tube under N2 and heated at 200 °C for
15 h, yielding Os2(CO)6(µ-η2,η4-(C6H4)2) (4) and Os4-
(CO)12(µ4-η2-(C6H3)Ph) (5) (eq 3); a large amount of Os3-
(CO)12 (33%) still retains intact. The different reactivity
biphenylene C-H bonds, instead of C-C bonds, are
activated by the osmium atoms. Nevertheless, this
reaction resembles previous observations for the reac-
tions of Os3(CO)10(NCMe)2 with benzene and toluene to
give the corresponding benzyne and tolyne complexes.20
Ch a r a cter iza tion of P r od u cts. Fe2(CO)5(µ-CO)(µ-
η2,η4-(C6H4)2) (1) forms air-stable, brownish-red crystals.
The 1H NMR and IR spectra data agree with those
previously reported by McWhinnie and co-workers14 for
1 resulting from the reaction of Fe3(CO)12 and diben-
zotellurophene ((C6H4)2Te).
Ru2(CO)5(µ-CO)(µ-η2,η4-(C6H4)2) (2) forms air-stable,
orange crystals. The FAB mass spectrum shows the
molecular ion at m/z 524 for 102Ru and ions correspond-
ing to successive loss of six carbonyls. The IR spectrum
shows a medium absorption at 1882 cm-1, indicating
the presence of a bridging carbonyl. The 1H NMR
spectrum (Figure 1) illustrates two doublet and two
of iron-triad clusters toward biphenylene is consistent
with a stronger M-M and M-CO bond as expected for
a third-row transition metal compared with a first-row
and a second-row metal.17
The reaction pathways leading to formation of com-
pounds 1-5 are not clear at this stage. Since pure bi-
phenylene is thermally stable to 170 °C, loss of carbo-
nyl ligands from the cluster or breaking a metal-metal
bond to generate an unsaturated species seems essen-
(18) Crabtree, R. H. Chem. Rev. 1985, 25, 245.
(19) Tachikawa, M.; Shapley, J . R. J . Organomet. Chem. 1977, 124,
C19.
(20) (a) Deeming, A. J .; Underhill, M. J . Chem. Soc., Dalton Trans.
1974, 1415. (b) Goundsmit, R. J .; J ohnson, B. F. G.; Lewis, J .; Raithby,
P. R.; Rosales, M. J . J . Chem. Soc., Dalton Trans. 1983, 2257.
(17) Bruce, M. I. in Comprehensive Organometallic Chemistry;
Pergamon Press: Oxford, U.K., 1982; Vol. 4, pp 661-662.

2480 Organometallics, Vol. 17, No. 12, 1998
Yeh et al.
F igu r e 2. Molecular structure of Ru2(CO)5(µ-CO)(µ-η2,η4-
(C6H4)2) (2). The hydrogen atoms have been artificially
omitted for clarity.
1
F igu r e 1. (1) H NMR and (2) 13C{1H} NMR spectra of
Ru2(CO)5(µ-CO)(µ-η2,η4-(C6H4)2) (2) obtained in CDCl3 at
20 °C.
triplet signals in the range δ 8.4-7.1 for the phenylene
protons. The downfield doublet signal at δ 8.34 can be
assigned to the protons ortho to the Ru-C bond, which
are expected to be deshielded relative to the other
protons.21 The 13C{1H} spectrum is also shown in
Figure 1. There are six resonance signals for the 12
biphenylene carbons ranging from δ 151.6 to 125.5,
implying a time-averaged Cs symmetry for the molecule.
The carbonyl ligands are fluxional at 20 °C, as indicated
by observing only one broad carbon resonance at δ 188.9.
Os2(CO)6(µ-η2,η4-(C6H4)2) (4) forms air-stable, yellow
crystals. The IR absorptions for the carbonyl groups
are observed between 2084 and 1974 cm-1 with no
indication of bridging carbonyl. To determine if differ-
ent metal sizes and the presence/absence of a bridging
carbonyl would affect the binding of the biphenylene
ligand, single-crystal X-ray diffraction studies of 2 and
4 were performed.
Os4(CO)12(µ4-η2-(C6H3)Ph) (5) forms air-stable, orange-
red crystals. The EI mass spectrum shows the molec-
ular ion peak at m/z ) 1256 for 192Os and ion multiplets
corresponding to successive loss of 12 carbonyls. The
isotopic distribution of the envelope surrounding the
molecular ion matches that expected for 5, and there is
a good agreement between the calculated mass distribu-
tion and the observed mass spectrum. The IR absorp-
tions in the carbonyl region show a pattern similar to
those recorded for alkyne butterfly clusters Os4(CO)12-
(µ4-η2-alkyne).22 The 1H NMR spectrum includes a
multiplet in the range δ 7.8-7.0 (5H), characteristic of
phenyl proton resonances, a singlet at δ 7.13 (1H), a
F igu r e 3. Molecular structure of Os2(CO)6(µ-η2,η4-(C6H4)2)
(4). The hydrogen atoms have been artificially omitted for
clarity.
doublet at δ 6.50 (1H), and a doublet at δ 6.32 (1H).
Apparently, the biphenylene molecule has changed its
appearance to a different type of ligand. A single-crystal
X-ray diffraction study of 5 was thus performed.
(µ-H)2Os3(CO)9(µ3-η2-C6H2(C6H4)) (6) forms air-stable,
yellow solids. The IR spectrum in the carbonyl region
greatly resembles those recorded for (µ-H)2Os3(CO)9(µ3-
η2-C6H4)20a and (µ-H)2Os3(CO)9(µ3-η2-C6H3CH3).20b The
1H NMR spectrum includes a singlet at δ -18.99 for
the bridging hydrides, a singlet at δ 7.02 for the benzyne
ring protons, and a multiplet in the range δ 7.04-6.94
assigned to the protons on the unactivated phenylene
ring.
Cr ysta l Str u ctu r e of 2. Crystals of Ru2(CO)5(µ-CO)-
(µ-η2,η4-(C6H4)2) (2) contain an ordered array of discrete
monomeric molecule units which are mutually sepa-
rated by normal van der Waals distances. The ORTEP
(22) (a) J ackson, R.; J ohnson, B. F. G.; Lewis, J .; Raithby, P. R.;
Sankey, S. W. J . Organomet. Chem. 1980, 193, C1. (b) Chen, H.;
J ohnson, B. F. G.; Lewis, J .; Raithby, P. R. J . Chem. Soc., Chem.
Commun. 1990, 373.
(21) Eisch, J . J . In Organometallic Syntheses; Eisch, J . J ., King, R.
B., Eds.; Academic Press: New York, 1981; Vol. 1, pp 94, 141.

Reactions of Biphenylene with Fe Group Clusters
Organometallics, Vol. 17, No. 12, 1998 2481
Ta ble 2. Selected Bon d Dista n ces (Å) a n d Bon d An gles (d eg) for Ru 2(CO)5(µ-Co)(µ-η2,η4-(C6H4)2) (2) a n d
Os2(CO)6(µ-η2,η4-(C6H4)2) (4)
2 (M ) Ru)
4 (M ) Os)
2 (M ) Ru)
4 (M ) Os)
Distances
Ml-M2
Ml-C1
Ml-C2
Ml-C3
M1-C5
M2-C4
M2-C5
M2-C6
Ml-C7
Ml-C14
M2-C7
M2-C12
M2-C13
M2-C14
2.6998(6)
1.910(5)
1.938(5)
1.920(6)
2.327(5)
1.859(5)
1.934(5)
1.886(5)
2.137(4)
2.125(4)
2.270(4)
2.423(4)
2.410(4)
2.311(4)
2.7247(11)
1.897(15)
1.937(14)
1.921(17)
C7-C8
1.418(7)
1.432(6)
1.350(8)
1.390(9)
1.346(9)
1.415(7)
1.474(7)
1.425(6)
1.419(6)
1.421(7)
1.360(7)
1.389(9)
1.344(8)
1.425(18)
1.463(16)
1.353(21)
1.432(20)
1.311(22)
1.423(18)
1.485(18)
1.459(18)
1.439(16)
1.406(19)
1.357(20)
1.42(3)
C7-C12
C8-C9
C9-C10
C10-C11
C11-C12
C12-C13
C13-C14
C13-C18
C14-C15
C15-C16
C16-C17
C17-C18
1.866(16)
1.933(13)
1.890(14)
2.087(12)
2.124(11)
2.366(12)
2.357(13)
2.356(12)
2.366(12)
1.305(23)
Angles
M2-M1-C1
M2-M1-C2
M2-M1-C3
M2-M1-C5
M2-M1-C7
M2-M1-C14
C1-M1-C2
C1-M1-C3
C1-M1-C5
C1-M1-C7
C1-M1-C14
C2-M1-C3
C2-M1-C5
C2-M1-C7
C2-M1-C14
C3-M1-C5
C3-M1-C7
C3-M1-C14
C5-M1-C7
C5-M1-C14
C7-M1-C14
M1-M2-C4
M1-M2-C5
M1-M2-C6
M1-M2-C7
M1-M2-C12
M1-M2-C13
M1-M2-C14
C4-M2-C5
C4-M2-C6
132.77(14)
114.43(14)
120.10(15)
44.49(12)
54.48(10)
55.73(11)
94.20(20)
93.91(22)
175.51(18)
88.33(19)
91.72(17)
92.02(22)
90.29(18)
94.34(20)
169.69(19)
85.93(20)
173.09(19)
95.99(20)
91.33(17)
83.84(16)
77.39(17)
138.30(15)
57.47(14)
123.24(14)
50.02(11)
72.70(10)
72.50(10)
49.43(10)
100.81(21)
91.77(20)
149.4(4)
104.1(4)
104.9(4)
C4-M2-C7
C4-M2-C12
C4-M2-C13
C4-M2-C14
C5-M2-C6
C5-M2-C7
C5-M2-C12
C5-M2-C13
C5-M2-C14
C6-M2-C7
C6-M2-C12
C6-M2-C13
C6-M2-C14
C7-M2-C12
C7-M2-C13
C7-M2-C14
C12-M2-C13
C12-M2-C14
C13-M2-C14
M1-C5-M2
M1-C5-O5
M2-C5-O5
M1-C7-M2
M1-C7-C8
M1-C7-C12
C7-C12-C13
C12-C13-C14
Ml-C14-M2
Ml-C14-C13
Ml-C14-C15
158.60(18)
123.27(18)
98.89(17)
100.46(18)
96.27(21)
98.64(18)
129.50(17)
122.89(18)
88.61(18)
94.89(18)
104.87(18)
135.99(19)
165.77(18)
35.33(15)
62.65(15)
71.11(16)
35.52(15)
62.25(15)
35.05(15)
78.04(18)
133.2(4)
140.2(5)
151.4(5)
115.8(5)
88.3(5)
96.9(6)
123.1(5)
93.1(5)
91.7(5)
119.0(5)
89.0(5)
114.1(5)
150.3(5)
143.9(5)
36.1(4)
62.8(4)
69.1(4)
36.7(4)
63.6(4)
36.0(4)
57.1(3)
56.8(3)
96.6(6)
96.0(6)
101.2(6)
101.0(5)
93.2(6)
90.3(5)
160.9(5)
161.9(5)
92.1(5)
79.2(5)
92.6(3)
164.6(4)
95.3(4)
47.8(3)
73.3(3)
73.1(3)
48.7(3)
96.4(5)
91.4(6)
148.7(4)
75.51(l4)
127.8(3)
115.7(3)
113.9(4)
115.3(4)
74.85(13)
115.8(3)
176.0(13)
75.1(4)
129.4(9)
117.2(9)
113.1(10)
115.3(9)
74.5(4)
114.9(8)
129.2(9)
127.7(3)
drawing is shown in Figure 3. Selected bond distances
and bond angles are collected in Table 2.
Ru1 atom with Ru1-C5-O5 ) 133.2(4)° and Ru2-C5-
O5 ) 148.7(4)°.
The Ru1 atom has inserted into the four-membered
ring of biphenylene, forming a metallacycle. On the
basis of the angles subtended, the coordination about
the Ru1 atom can be described as a capped octahedron
with the Ru2 atom in the capping position. On the other
hand, the coordination about the Ru2 atom is a three-
legged piano stool by considering the (Ru1, C7, C12,
C13, C14) unit as a metallacyclopentadienyl ligand to
bind the Ru2 atom in an η5-fashion. The Ru1-Ru2
length is 2.6998(6) Å, typical of a ruthenium-ruthenium
single bond. The Ru1 and Ru2 atom are each linked to
three and two terminal carbonyl ligands, respectively,
with the Ru-C-O angles in the range 175.5(4)-178.7-
(4)°. The ruthenium-terminal carbonyl distances range
from 1.859(5) to 1.938(5) Å, where the longest Ru1-C2
and Ru1-C3 bond lengths might indicate some trans
influence from the opposite C14-Ru1 and C7-Ru1
bonds. The carbonyl C5-O5 bridges the Ru1-Ru2 edge
unsymmetrically, such that the Ru1-C5 length (2.327-
(5) Å) is ca. 0.4 Å longer than that of the Ru2-C5 length
(1.934(5) Å), and the Ru-C-O angle is bent toward the
The two phenylene rings (C7∼C12 and C13∼C18) are
each planar to within 0.01 and 0.02 Å, respectively while
the metallacyclopentadienyl ring is puckered, as evi-
denced by the torsional angles: Ru1-C7-C12-C13 )
11.9(2)°, Ru1-C14-C13-C12 ) 7.8(2)°, C12-C7-Ru1-
C14 ) 12.3(2)°, and C14-C13-C12-C7 ) 2.7(2)°. The
phenylene C-C distances are not equal, ranging from
1.344(8) (C17-C18) to 1.432(6) Å (C7-C12). This may
indicate little aromaticity of the phenylene rings, ap-
parently due to complexation with the Ru2 atom. The
C12-C13 length (1.474(7) Å) is slightly shorter than
that in free biphenylene (1.52 Å) and may imply some
inter-ring electron delocalization. The Ru1-C bonds at
2.137(4) Å to C7 and 2.125(4) Å to C14, characteristic
of σ-bonds, are shorter than the distances of π interac-
tions associated with the Ru2 atom. The Ru2-C bond
distances involving the inner carbon atoms, 2.423(4)
(C12), 2.410(4) Å (C13), are significantly longer than
those involving the outer atoms, 2.270(4) (C7) and 2.311-
(4) Å (C14). If the neutral biphenylenyl ligand donates
2e- to Ru1 and 4e- to Ru2 and the bridging carbonyl

2482 Organometallics, Vol. 17, No. 12, 1998
Yeh et al.
Ta ble 3. Selected Bon d Dista n ces a n d Bon d
An gles for Os4(CO)12(µ4-η2-(C6H3)P h ) (5)
Distances
Os1-Os2
Os1-C1
2.7489(18)
1.90(3)
1.908(25)
2.280(21)
2.8830(18)
1.94(3)
1.57(4)
1.42(4)
1.43(3)
1.37(4)
Os1-Os4
Os1-C2
Os1-C13
Os2-Os3
Os2-C4
Os2-C6
Os2-C13
Os3-Os4
Os3-C7
Os3-C8
Os3-C9
Os3-C13
Os3-C14
Os4-C11
Os4-C14
2.7549(16)
1.95(3)
2.297(22)
2.7784(14)
1.87(3)
Os1-C3
Os1-C14
Os2-Os4
Os2-C5
1.91(3)
C13-C14
C13-C18
C14-C15
C15-C16
C16-C17
C17-C18
C17-C19
Os4-C10
Os4-C12
2.150(23)
2.7326(17)
1.92(3)
1.89(3)
1.87(3)
2.275(22)
2.298(23)
1.81(3)
1.41(4)
1.37(3)
1.48(4)
1.94(3)
1.89(3)
2.101(23)
F igu r e 4. Molecular structure of Os4(CO)12(µ4-η2-(C6H3)-
Ph) (5). The hydrogen atoms have been artificially omitted
for clarity.
Angles
Os2-Os1-Os4
Os2-Os1-C1
Os2-Os1-C2
Os2-Os1-c3
Os2-Os1-C13
Os2-Os1-C14
Os4-Os1-C1
Os4-Os1-C2
Os4-Os1-C3
Os4-Os1-C13
Os4-Os1-C14
C1-Os1-C2
63.18(5)
107.3(8)
159.8(7)
91.0(8)
Os1-Os4-C10
Os1-Os4-C11
Os1-Os4-C12
Os1-Os4-C14
Os2-Os4-Os3
Os2-Os4-C10
Os2-Os4-C11
Os2-Os4-C12
Os2-Os4-C14
Os3-Os4-C10
Os3-Os4-C11
Os3-Os4-C12
Os3-Os4-C14
C10-Os4-C11
C10-Os4-C12
C10-Os4-C14
C11-Os4-C12
C11-Os4-C14
C12-Os4-C14
C13-Os1-C14
Os1-Os2-Os4
Os1-Os2-C5
Os1-Os2-C13
Os3-Os2-C4
Os3-Os2-C6
Os1-C13-Os2
Os1-C13-Os3
Os1-C13-C14
Os4-Os2-C13
C4-Os2-C5
145.8(10)
120.1(11)
76.7(7)
donates 1e- to each metal, both ruthenium atoms obey
the 18-electron rule.
54.0(6)
49.4(6)
73.3(6)
161.2(7)
96.8(8)
100.8(7)
71.9(6)
59.24(4)
96.0(10)
160.4(10)
103.8(7)
72.8(7)
Cr ysta l Str u ctu r e of 4. The ORTEP drawing of Os2-
(CO)6(µ-η2,η4-(C6H4)2) (4) is shown in Figure 3. Selected
bond distances and bond angles are given in Table 2.
The overall geometry of 4 is very similar to that of 3,
except that no bridging carbonyl is present for 4. Thus,
the coordination about the Os1 atom is a distorted
octahedron, and the coordination about the Os2 atom
can be described as a three-legged piano stool by
considering the metallacycle as an η5-ligand. The Os1-
Os2 length of 2.725(1) Å is significantly shorter than
that observed for the parent compound Os3(CO)12,23 in
which Os-Os(average) ) 2.877(3) Å.
The biphenylenyl group (C7∼C18) and the Os1 atom
are coplanar to within (0.02 Å. The ring carbon-
carbon bonds are localized, such that the C8-C9, C10-
C11, C15-C16, and C17-C18 bond lengths, ranging
from 1.31(2) to 1.36(3) Å, are typical of carbon-carbon
double bonds. The C7-C12 and C13-C14 distances are
lengthened to 1.46(2) Å, apparently due to π-donation
to the Os2 atom. The C12-C13 distance is 1.49(2) Å.
Os1 and Os2 atoms are each linked to three terminal
carbonyl ligands. The Os-C-O angles are in the range
176(1)-178(1)°, and the Os-CO distances range from
1.87(2) to 1.94(1) Å. The Os1 atom forms σ-bonds to
C7 and C14 at 2.09(1) and 2.12(1) Å, respectively. The
Os2 atom is situated right behind the centroid of the
butadiene C7-C12-C13-C14 unit and is about equally
bonded to these atoms, with Os-C ) 2.36 ( 0.02 Å.
Since no bridging carbonyl is present, the Os-Os
interaction is best described as a dative bond by donat-
ing two nonbonding electrons from Os2 to Os1 to satisfy
the 18-electron rule for each osmium atom.
91.0(8)
48.2(6)
102.8(9)
163.0(7)
54.9(7)
91.7(16)
89.8(11)
145.3(10)
94.1(11)
90.6(14)
124.5(10)
40.1(9)
58.51(4)
86.2(8)
54.3(6)
128.1(10)
79.1(8)
76.3(7)
121.8(10)
69.4(12)
71.2(6)
95.2(12)
92.4(14)
70.7(11)
92.8(9)
121.6(10)
77.8(7)
70.5(11)
102.9(7)
49.1(6)
91.1(11)
95.4(11)
89.5(9)
114.7(9)
95.9(11)
124.3(9)
91.5(9)
139.4(10)
148.9(9)
92.58(5)
101.1(10)
166.5(9)
57.69(4)
135.8(7)
53.1(6)
87.9(11)
144.4(8)
122.9(9)
77.7(8)
C1-Os1-C3
C1-Os1-C13
C1-Os1-C14
C2-Os1-C3
C2-Os1-C13
C2-Os1-C14
C3-Os1-C13
C3-Os1-C14
Os1-Os2-Os3
Os1-Os2-C4
Os1-Os2-C6
Os3-Os2-Os4
Os3-Os2-C5
Os3-Os2-C13
Os4-Os2-C4
Os4-Os2-C5
Os4-Os2-C6
Os2-C13-Os3
Os2-C13-C14
C4-Os2-C13
C5-Os2-C6
C6-Os2-C13
Os2-Os3-Os4
Os2-Os3-C7
Os2-Os3-C8
Os3-C14-Os4
Os3-C14-C13
Os4-Os3-C7
Os4-Os3-C8
Os4-Os3-C13
C7-Os3-C8
107.8(14)
153.4(13)
92.5(12)
112.5(11)
63.08(4)
97.7(8)
C4-Os2-C6
Os3-C13-C14
C5-Os2-C13
Os1-C14-Os3
Os1-C14-Os4
Os1-C14-C13
Os2-Os3-C9
Os2-Os3-C13
Os2-Os3-C14
Os4-C14-C13
Os4-Os3-C9
Os4-Os3-C14
C7-Os3-C9
C7-Os3-C14
C8-Os3-C13
C9-Os3-C13
C13-Os3-C14
Os1-Os4-Os3
160.7(8)
76.7(7)
69.2(12)
98.6(8)
72.5(5)
108.1(14)
163.3(7)
48.4(6)
92.1(12)
146.8(10)
118.8(10)
91.4(9)
100.4(8)
72.6(6)
94.4(11)
146.4(10)
91.5(11)
89.3(10)
120.8(10)
58.31(4)
C7-Os3-C13
C8-Os3-C9
C8-Os3-C14
C9-Os3-C14
Os1-Os4-Os2
Cr ysta l Str u ctu r e of 5. An ORTEP diagram of Os4-
(CO)12(µ4-η2-(C6H3)Ph) (5) is shown in Figure 4. Se-
lected bond distances and angles are given in Table 3.
This complex consists of a tetraosmium butterfly frame-
work bridged by a phenylbenzyne moiety. Complex 5
is the first butterfly cluster of the type [Os4(aryne)-
(CO)12], although there are several alkyne complexes of
this type.22 The ruthenium analogues Ru4(µ4-η2-naph-
thyne)(CO)12] and [Ru4(µ4-η2-phenanthryne)(CO)12] were
recently reported by Deeming and Speel.24
40.1(9)
93.45(5)
Each osmium atom is associated with three terminal
carbonyl ligands. The Os-CO distances vary from 1.81-
(3) (Os4-C11) to 1.95(3) Å (Os1-C2), while the Os-
C-O angles fall in the range 171(3)-173(3)°. The two
hinge Os(CO)3 groups are staggered, apparently to
reduce steric interactions between the CO ligands.
(23) Churchill, M. R.; DeBoer, B. G. Inorg. Chem. 1977, 16, 878.
(24) Deeming, A. J .; Speel, D. M. Organometallics 1997, 16, 289.

Reactions of Biphenylene with Fe Group Clusters
Organometallics, Vol. 17, No. 12, 1998 2483
The benzyne ring carbons are coplanar to within 0.01-
(3) Å. The Os-C(benzyne) distances to the hinge Os2
and Os4 atoms, averaging 2.13(2) Å, are significantly
shorter than those to the wingtip Os1 and Os3 atoms,
averaging 2.29(2) Å. It appears that the benzyne ligand
forms σ-bonds with the hinge osmium atoms while it
donates its π-electrons to the wingtip osmium atoms.
The lengthened C13-C14 bond distance of 1.57(4) Å,
typical of a carbon-carbon single bond (i.e., 1.53 Å for
ethane), is likely due to back-donation of electrons from
the Os atoms into the benzyne π* orbitals. The remain-
ing benzyne ring carbon-carbon distances show an
alternative long-short pattern, implying little aroma-
ticity of this ring. The dihedral angle between the
benzyne plane and the phenyl plane is 33(1)°.
conditions also lead to cluster fragmentation with the
cluster nuclearity changing from 3 to 2, 4, and 6. Com-
pounds 1, 2, and 4 contain a metallacyclopentadienyl
group arising from insertion of a metal atom into the
central C-C bond of biphenylene. Compound 5 is the
first butterfly cluster of the type Os4(CO)12(aryne), in
which the phenylbenzyne ligand is derived from rear-
rangement of biphenylene molecule. The dihydrido
complex 6 comes from C-H bond activation of biphen-
ylene on the triosmium framework.
Ack n ow led gm en t. We are grateful for support of
this work by the National Science Council of Taiwan.
Su p p or tin g In for m a tion Ava ila ble: Complete tables of
crystallographic data, positional parameters, anisotropic ther-
mal parameters, bond angles, bond distances, and torsional
angles of 2, 4, and 5 (24 pages). Ordering information is given
on any current masthead page.
Con clu sion s
The results presented here describe interesting C-C
and C-H bond activation of biphenylene by the iron-
triad carbonyl clusters. The harsh thermal reaction
OM9800445