Synthesis and reactivity of Ir(CO)(η2-C2R2)(η5-C 9H7) (R = Ph, Tol). Alkyne coupling and arene C-H bond activation forming a substituted butadiene ligand

Article abstract of DOI:10.1021/om970579i

The reaction of Ir(CO)(η²-C₈H₁₄)(η⁵-C ₉H₇) with excess C₂R₂ (R = Ph, Tol) in benzene at reflux leads to a mixture containing Ir(CO(η²-C₂R₂)(η⁵-C ₉H₇) (1a, R = Ph; 1b, R = Tol), Ir₂(CO)₂(μ-C₂R₂)(η ⁵-C₉H₇)₂ (2a, R = Ph; 2b, R = Tol), and Ir(η⁴-HC₄R₄R′)(η ⁵-C₉H₇) (3a, R = Ph, R′ = Ph; 3b, R = Tol, R′ = Ph). Conducting the reaction in benzene-d₆, toluene, or m-xylene leads to 1 and 2 and Ir(η⁴-DC₄R₄R′)(η ⁵-C₉H₇) (3c, R = Tol, R′ = C₆D₅) or Ir(η⁴-HC₄R₄R′)(η ⁵-C₉H₇) (3d, R = Ph, R′ = C₆H₄Me; 3e, R = Ph, R′ = C₆H₃Me₂; 3f, R = Tol, R′ = C₆H₄Me). The structures of compounds 2a and 3b have been determined by X-ray diffraction. Compound 2a contains a dimetallacyclobutene framework with the CO ligands adopting a trans orientation with respect to the Ir₂C₂ mean plane. The indenyl ligands take positions opposite the carbonyls at each Ir center. Compound 3b contains a 1-phenyl-1,2,3,4-tetratolyl1,3-butadiene ligand formed through both alkyne coupling and CH bond activation of the solvent benzene. The direct reactions of 1 with excess Ir(CO)(η²-C₈H₁₄)(η⁵-C ₉H₇) or C₂R₂ lead to higher yields of 2 or 3, respectively.

Full text of DOI:10.1021/om970579i

4816
Organometallics 1997, 16, 4816-4823
Syn th esis a n d Rea ctivity of Ir (CO)(η2-C2R2)(η5-C9H7)
(R ) P h , Tol). Alk yn e Cou p lin g a n d Ar en e C-H Bon d
Activa tion F or m in g a Su bstitu ted Bu ta d ien e Liga n d
Matthew C. Comstock and J ohn R. Shapley*
School of Chemical Sciences, University of Illinois, Urbana, Illinois 61801
Received J uly 8, 1997X
The reaction of Ir(CO)(η2-C8H14)(η5-C9H7) with excess C2R2 (R ) Ph, Tol) in benzene at
reflux leads to a mixture containing Ir(CO)(η2-C2R2)(η5-C9H7) (1a , R ) Ph; 1b, R ) Tol),
Ir2(CO)2(µ-C2R2)(η5-C9H7)2 (2a , R ) Ph; 2b, R ) Tol), and Ir(η4-HC4R4R′)(η5-C9H7) (3a , R )
Ph, R′ ) Ph; 3b, R ) Tol, R′ ) Ph). Conducting the reaction in benzene-d6, toluene, or
m-xylene leads to 1 and 2 and Ir(η4-DC4R4R′)(η5-C9H7) (3c, R ) Tol, R′ ) C6D5) or Ir(η4-
HC4R4R′)(η5-C9H7) (3d , R ) Ph, R′ ) C6H4Me; 3e, R ) Ph, R′ ) C6H3Me2; 3f, R ) Tol, R′ )
C6H4Me). The structures of compounds 2a and 3b have been determined by X-ray diffraction.
Compound 2a contains a dimetallacyclobutene framework with the CO ligands adopting a
trans orientation with respect to the Ir2C2 mean plane. The indenyl ligands take positions
opposite the carbonyls at each Ir center. Compound 3b contains a 1-phenyl-1,2,3,4-tetratolyl-
1,3-butadiene ligand formed through both alkyne coupling and CH bond activation of the
solvent benzene. The direct reactions of 1 with excess Ir(CO)(η2-C8H14)(η5-C9H7) or C2R2
lead to higher yields of 2 or 3, respectively.
niques, while purification procedures were done in air. Ir(CO)-
In tr od u ction
6
(η2-C8H14)(η5-C9H7)3 and C2Tol2 were prepared by literature
methods. Diphenylacetylene (Aldrich) was used without fur-
ther purification. Solvents for preparative use were dried by
standard methods and distilled. The deuterated solvents,
(CD3)2CO and CD2Cl2 (Cambridge Isotope Laboratories), were
used as received. Proton NMR spectra were recorded on
General Electric spectrometers at 300 or 500 MHz and on
Varian spectrometers at 500 or 750 MHz; the reference was a
residual proton resonance in the deuterated solvent. Infrared
spectra were recorded on a Perkin-Elmer 1750 FT-IR spec-
trometer. Field-desorption (FD) mass spectra were recorded
on a Finnigan-Mat 731 spectrometer by the staff of the Mass
Spectrometry Laboratory of the School of Chemical Sciences.
Microanalyses were performed by the staff of the School
Microanalytical Laboratory.
We have reported the synthesis of the indenyl iridium
1
trimer Ir3(µ-CO)3(η5-C9H7)3 and have attempted with-
out current success to prepare alkyne derivatives of this
cluster in analogy with the preparation of Ir3(µ-CO)(µ3-
C2R2)(η5-C5H5)3 from Ir3(CO)3(η5-C5H5)3.2 As an indirect
approach to the same goal, we have investigated the
formation of the mononuclear alkyne complex Ir(CO)-
(η2-C2R2)(η5-C9H7). It appears that an appropriate
precursor would be Ir(CO)(η2-C8H14)(η5-C9H7), since the
cyclooctene ligand is readily replaced by ethylene,3 C60,4
and other π-bonding ligands.5 We now report that the
reaction of Ir(CO)(η2-C8H14)(η5-C9H7) with C2R2 (R ) Ph,
Tol) does indeed lead to the mononuclear alkyne com-
pounds Ir(CO)(η2-C2R2)(η5-C9H7) (1a , R ) Ph; 1b, R )
Tol). Furthermore, subsequent reaction of 1 with Ir-
(CO)(η2-C8H14)(η5-C9H7) forms the dinuclear compounds
Ir2(CO)2(µ-C2R2)(η5-C9H7)2 (2a , R ) Ph; 2b, R ) Tol).
However, we have unexpectedly found that 1 also reacts
with the aromatic solvent (e.g., benzene) as well as an
additional molecule of C2R2 to form a complex with a
substituted butadiene ligand, e.g., Ir(η4-HC4R4R′)(η5-
C9H7) (3a , R ) Ph, R′ ) Ph; 3b, R ) Tol, R′ ) Ph) (see
Scheme 1).
Proton correlation spectra (1H COSY) were recorded on a
GE GN500 spectrometer; data was collected in the absolute-
value mode. A total of 4 transients of 512 data points were
recorded for each of the 256 increments of t1 with a relaxation
delay of 0.3 s. The data matrix was zero-filled once in the f2
dimension before transformation and symmetrized after trans-
formation. Proton-detected 1H-13C correlation spectra were
recorded on a Varian Unity Inova 500 MHz spectrometer by
Dr. Vera Mainz.
Syn th esis of Ir (CO)(η2-C2R2)(η5-C9H7). Meth od A.
A
solution of C2Ph2 (200 mg, 1.12 mmol) in benzene (10 mL) was
stirred and heated at reflux, and a benzene solution (10 mL)
of Ir(CO)(η2-C8H14)(η5-C9H7) (50 mg, 0.112 mmol) was added
slowly over 1 h through an addition funnel. The mixture was
heated at reflux for an additional 7 h, resulting in a light
orange solution. The solvent was removed under vacuum, and
the residue was redissolved in dichloromethane. A small
amount of neutral alumina I (Aldrich) was added, and the
mixture was dried under vacuum and placed on a 20 cm × 1
cm column of neutral alumina I. Elution with hexane removed
excess C2Ph2, and elution with a 4:1 mixture of hexane and
dichloromethane removed a yellow band. The yellow fraction
was concentrated on a rotary evaporator and placed on five
Exp er im en ta l Section
Gen er a l P r oced u r es. All reactions were conducted under
an atmosphere of nitrogen by using standard Schlenk tech-
X Abstract published in Advance ACS Abstracts, August 15, 1997.
(1) Comstock, M. C.; Wilson, S. R.; Shapley, J . R. Organometallics
1994, 13, 3805.
(2) Clauss, A. D.; Shapley, J . R.; Wilker, C. N.; Hoffmann, R.
Organometallics 1984, 3, 619.
(3) Szajek, L. P.; Lawson, R. J .; Shapley, J . R. Organometallics 1991,
10, 357.
(4) Koefod, R. S.; Hudgens, M. F.; Shapley, J . R. J . Am. Chem. Soc.
1991, 113, 8957.
(5) Szajek, L. P.; Shapley, J . R. Organometallics 1994, 13, 1395.
(6) Cope, A. C.; Smith, D. S.; Cotter, R. J .; Price, C. C.; McKeon, T.
F., J r. Organic Syntheses; J ohn Wiley & Sons: New York, 1963; Collect.
Vol. IV, p 377.
S0276-7333(97)00579-7 CCC: $14.00 © 1997 American Chemical Society

Synthesis of Ir(CO)(η2-C2R2)(η5-C9H7)
Organometallics, Vol. 16, No. 22, 1997 4817
Sch em e 1
preparative silica gel TLC plates (Aldrich). Elution with
hexane/ dichloromethane (4:1) provided, in order of elution,
yellow 1a (30.8 mg, 0.060 mmol, 53%), orange 2a (trace,
identified by infrared spectroscopy), and yellow 3a (12.9 mg,
0.017 mmol, 15%).
Meth od B. A solution of C2Ph2 (200 mg, 1.12 mmol) and
Ir(CO)(η2-C8H14)(η5-C9H7) (50 mg, 0.112 mmol) in benzene (20
mL) was stirred and heated at reflux for 8 h, resulting in an
orange solution. The reaction mixture was separated in the
same manner as in method A, providing 1a (18.9 mg, 0.037
mmol, 33%), 2a (3.6 mg, 0.004 mmol, 4%), and 3a (1.4 mg,
0.022 mmol, 20%).
) C6H3Me2; 3f, R ) Tol, R′ ) C6H4Me), respectively. Com-
pounds 3c, 3d , 3e, and 3f were identified by comparing their
TLC behavior with 3a and 3b and by the molecular ions in
their FD-mass spectra (3c, m/ z 804; 3d , m/ z 756; 3e, m/ z
770; 3f, m/ z 812).
R ea ct ion of Ir (CO)(η2-C2P h 2)(η5-C9H 7) w it h E xcess
C2P h 2. A solution of 1a (20 mg, 0.039 mmol) and C2Ph2 (69
mg, 0.39 mmol) in benzene (10 mL) was stirred and heated at
reflux for 14 h, resulting in a yellow solution. The solvent was
removed under vacuum, and the residue was purified in the
same manner as above to give 3a (23.7 mg, 0.032 mmol, 82%).
Rea ction of Ir (CO)(η2-C2P h 2)(η5-C9H7) w ith excess Ir -
(CO)(η2-C8H14)(η5-C9H7). A stirred solution of 1a (20 mg,
0.039 mmol) and Ir(CO)(η2-C8H14)(η5-C9H7) (26 mg, 0.059
mmol) in toluene (10 mL) was heated at reflux for 8 h,
resulting in a dark orange solution. The solvent was removed
under vacuum, and the residue was redissolved in dichlo-
romethane and placed on four preparative silica gel TLC plates
(Aldrich). Elution with hexane/dichloromethane (4:1) pro-
vided, in order of elution, Ir(CO)(η2-C8H14)(η5-C9H7) (4.3 mg,
0.010 mmol, 17% recovery), 1a (1.3 mg, 0.003 mmol, 6%
recovery), and 2a (14.0 mg, 0.016 mmol, 45% based on
unrecovered 1a ).
X-r a y Str u ctu r e Deter m in a tion s of 2a a n d 3b. X-ray
quality crystals were grown by slowly evaporating hexane
solutions of 2a and 3b. The crystals were mounted with oil
(Paratone-N, Exxon) on thin glass fibers. Data were collected
at 198 K on an Siemens Platform/CCD diffractometer. Crystal
and refinement details are given in Table 2. Scattering factors
and anomalous dispersion terms were taken from standard
tables.7 The structures were solved by direct methods using
Repeating method A using C2Tol2 (231 mg, 1.12 mmol) and
Ir(CO)(η2-C8H14)(η5-C9H7) (50 mg, 0.112 mmol) provided 1b
(22.0 mg, 0.041 mmol, 36%), 2b (2 mg, 0.002 mmol, 2%), and
3b (11.3 mg, 0.014 mmol, 13%).
Characterization data: 1a , m/ z 514 (M+), νCO 1981 cm-1
,
mp 153-154 °C. Anal. Calcd: C, 56.12; H, 3.34. Found: C,
56.12; H, 3.59. 1b, m/ z 542 (M+), νCO 1981 cm-1, mp 148-
150 °C. Anal. Calcd: C, 57.65; H, 3.91. Found: C, 56.85; H,
3.83. 2a , m/ z 850 (M+), νCO 1961 cm-1, mp 190-192 °C. Anal.
Calcd: C, 48.10; H, 2.75. Found: C, 47.67; H, 2.85. 2b, m/ z
878 (M+), νCO 1961 cm-1. 3a , m/ z 742 (M+), mp 233-235 °C.
Anal. Calcd: C, 69.61; H, 4.48. Found: C, 68.82; H, 4.58. 3b,
m/ z 798 (M+), mp 195-197 °C. Anal. Calcd: C, 70.74; H,
5.18. Found: C, 69.41; H, 5.16. Proton NMR data for
compounds 1a , 1b, 2a , 2b, 3a , and 3b are collected in Table
1.
Carbon NMR data for compound 3b: δ 140-125 (tolyl,
phenyl, indenyl C4-C7), 107.0, 105.1 (indenyl C8, C9), 88.8, 88.2
(diene C2, C3), 81.5, 80.3, 79.4 (indenyl C1-C3), 60.4 (diene C4),
51.9 (diene C1-H), 21.0 (2C), 20.9 (1C), 20.8 (1C) (tolyl methyl).
Conducting the reaction of C2R2 with Ir(CO)(η2-C8H14)(η5-
C9H7) in C6D6, toluene, or m-xylene provided 1 and 2 and Ir-
(η4-DC4R4R′)(η5-C9H7) (3c, R ) Tol, R′ ) C6D5) or Ir(η4-
HC4R4R′)(η5-C9H7) (3d , R ) Ph, R′ ) C6H4Me; 3e, R ) Ph, R′
(7) International Tables for X-ray Crystallography; Wilson, A. J . C.,
Ed.; Kluwer Academic Publishers: Dordrecht, The Nethelands 1992;
Vol. C, (a) scattering factors, pp 500-502; (b) anomalous dispersion
corrections, pp 219-222.

4818 Organometallics, Vol. 16, No. 22, 1997
Ta ble 1. Selected 1H NMR Da ta for Com p ou n d s 1-3
indenyla
Comstock and Shapley
cmpd
H2
H1, H3
H4, H7
H5, H6
aryl
methyl
1a b,c
1bb,c
2a b,h,i
2bb,h,j
3a h,l
6.62 td
6.61 tf
4.84 m
4.81 m
6.41 m
6.34 m
5.77 dd
7.45-7.23e
7.45-7.23e
7.45-7.23e
5.75 df
7.37 m
7.23 m
7.31 d, 7.12 dg
7.43-6.77e
2.36 s
2.20 s
6.31 m, 5.45m
6.33 m, 5.40 m
5.73 m, 4.85 m
5.58 m, 4.75 m
7.43-6.77e
7.26 m, 7.39 m
7.59 m, 7.45 m
7.59 m, 7.44 m
7.43-6.77e
6.92 m, 7.04 m
7.45 m, 7.40 m
7.44 m, 7.39 m
6.70 d, 6.85 dk
7.09-6.14m
6.95-6.13o
3bh,n
2.05p
The labeling scheme shown below was used for the indenyl proton resonances. Recorded at 300 MHz. c In CD2Cl2 at 20 °C. J 12
)
)
a
b
d
2.6 Hz. e Signals for H4-H7 and the aryl protons appear throughout this region. See spectra included as Supporting Information. J 12
f
g
h
i
2.5 Hz. J ) 8.1 Hz. In acetone-d6 at 20 °C. Simulation gives J 12 ) 2.7, J 23 ) 2.9, J 13 ) 1.6, J 17 ) 0.8, J 34 ) 0.9, J 67 ) 8.4, J 56 ) 6.9,
j
J 45 ) 8.4, J 57 ) 1.0, J 46 ) 1.0, and J 47 ) 1.0 Hz. Simulation gives J 12 ) 2.6, J 23 ) 2.9, J 13 ) 1.5, J 17 ) 0.8, J 34 ) 0.8, J 67 ) 8.4, J 56
)
k
l
m
6.8, J 45 ) 8.3, J 57 ) 1.1, J 46 ) 1.0, and J 47 ) 1.0 Hz. J ) 8.0 Hz. Recorded at 500 MHz. Signals for alkyne phenyl substitutents
appear throughout this region. Signals for groups derived from benzene: C6H5, δ 7.80 (1H), 7.37 (1H), 7.30 (1H), 7.25 (1H), 7.15 (1H), all
n
multiplets; dCH, δ 2.55 (1H), singlet. Recorded at 750 MHz. o Signals for the alkyne tolyl substitutents appear throughout this region.
Signals for groups derived from benzene: C6H5, δ 7.76 (1H), 7.35 (1H), 7.24 (2H), 7.15 (1H), all multiplets; dCH, δ 2.47 (1H), singlet.
p
Overlap with acetone-d5 signals; in CD2Cl2, δ 2.14, 2.13, 2.12, 2.10, all singlets.
Ta ble 2. Cr ysta llogr a p h ic Da ta for 2a a n d 3b
compound
2a
3b
formula
fw
C34H24Ir2O2
848.93
C47H41Ir
798.00
temperature, K
198(2)
198(2)
λ, Å
0.710 73 (Mo KR)
P21/c, monoclinic
12.7082(4)
10.7592(3)
19.4867(6)
90
94.09
90
2657.64(14)
4
2.122
0.710 73 (Mo KR)
Pbca, orthorhombic
9.7051(2)
19.9195(4)
37.2596(9)
90
space group, system
a, Å
b, Å
c, Å
R, deg
â, deg
γ, deg
V, Å3
Z
90
90
7203.1(3)
8
1.472
F
calcd, g cm-3
F(000)
1592
3200
cryst size, mm3
0.20 × 0.22 × 0.24
0.10 × 0.20 × 0.36
θ range, deg
index ranges
Itot (unique,Ri)
1.61-28.28
2.04-28.32
-15 e h e 16, -12 e k e 13, -25 e l e 25
16 736 (6272, 0.0826)
integration, 10.035
0.2324/0.1469
-12 e h e 12, -18 e k e 26, -47 e l e 49
43 896 (8794, 0.0608)
integration, 3.739
0.6936/0.4372
abs corr, µ, mm-1
max/min transmission
refinement method
data/restraints/parameters
goodness of fit (F2)a
R1b, wR2 [I > 2σ(I)]c
R1b, wR2 (all data)c
largest diff peak and hole, eÅ-3
full-matrix least-squares, F2
6267/0/343
1.010
0.0393, 0.1201
0.0497, 0.1365
full-matrix least-squares, F2
8779/0/433
1.094
0.0431, 0.1296
0.0714, 0.1608
+1.791 and -2.391
+1.322 and -0.758
a
2
b
GOF ) [∑[w(Fo - Fc2)2]/(n - p)]1/2; n ) number of reflections, p ) total number of parameters refined. R1 ) ∑||Fo| - |Fc||/-1|Fo|.
c wR2 ) [∑[w(Fo - Fc2)2]/∑[w(Fo2)2]]1/2
.
2
the Siemens SHELXTL package of programs;8-10 correct
positions for the metal atoms were deduced from E-maps. One
cycle of isotropic least-squares refinement followed by an
unweighted difference Fourier synthesis revealed positions for
the remaining non-H atoms. Hydrogen atoms were included
as fixed idealized contributors. H atom Us were assigned as
1.2Ueq of adjacent C atoms. Non-H atoms were refined with
anisotropic thermal coefficients. Successful convergence of the
full-matrix least-squares refinements on F2 were indicated by
the maximum shift/error for the last cycle.10 In both cases,
the highest peaks in the final difference Fourier maps were
in the vicinity of the metal atoms; the final maps had no other
significant features. The refined positional parameters are
given in the Supporting Information; selected structural data
are displayed in Tables 3 and 4.
Resu lts a n d Discu ssion
Syn th esis of Com p ou n d s 1-3. The reaction of Ir-
(CO)(η2-C8H14)(η5-C9H7) with 10 equiv of diphenylacety-
lene in benzene at reflux leads to a mixture of products
identified as the mononuclear alkyne complex Ir(CO)-
(η2-C2Ph2)(η5-C9H7) (1a ), the dinuclear alkyne complex
Ir2(CO)2(µ-C2Ph2)(η5-C9H7)2 (2a ), and the mononuclear
diene complex Ir(η4-HC4Ph5)(η5-C9H7) (3a ). Infrared
spectra obtained during the course of the reaction show
(8) Sheldrick, G. M. SHELXTL Version 5; Siemens Analytical X-Ray
Instruments, Inc.: Madison, WI, 1994.
(9) Sheldrick, G. M. SHELXS-86. Acta Crystallogr. 1990, A46, 467.
(10) Sheldrick, G. M. SHELXL-93; University of Go¨ttingen: Go¨t-
tingen, Germany, 1993.

Synthesis of Ir(CO)(η2-C2R2)(η5-C9H7)
Organometallics, Vol. 16, No. 22, 1997 4819
isolated 1 with Ir(CO)(η2-C8H14)(η5-C9H7) or 1 with C2R2
lead to higher yields of 2 or 3, respectively.
Ta ble 3. Selected Str u ctu r a l Da ta for 2a
Internuclear Distances (Å)
Ir1-Ir2
Ir1-C40
Ir2-C30
Ir1-C11
Ir1-C12
Ir1-C13
Ir1-C14
Ir1-C19
Ir1-C1
2.6750(4)
2.069(7)
2.078(7)
2.279(7)
2.241(8)
2.250(7)
2.359(7)
2.355(8)
1.840(7)
1.141(9)
C30-C40
C30-C31
C40-C41
Ir2-C21
Ir2-C22
Ir2-C23
Ir2-C24
Ir2-C29
Ir2-C2
1.330(10)
1.479(9)
1.468(10)
2.237(8)
2.239(8)
2.225(7)
2.356(8)
2.368(7)
1.830(8)
1.154(9)
Ch a r a cter iza tion of 1. The field-desorption mass
spectra of 1a and 1b show clear molecular ions consis-
tent with the formation of mononuclear alkyne com-
pounds, Ir(CO)(C2R2)(C9H7). The infrared spectra of
both 1a and 1b in hexane show one carbonyl stretching
band at 1981 cm-1; the tolyl substituents in 1b do not
noticeably affect the stretching frequency. The 1H NMR
spectra of both 1a and 1b (see Table 1 and Figure S-1
in Supporting Information) are consistent with sym-
metric molecules that possess a mirror plane bisecting
the indenyl ligand and passing through the iridium
atom and the midpoint of the CtC vector.
C1-O1
C2-O2
Bond Angles (deg)
70.4(2)
71.6(2)
5.33(45)
C40-Ir1-Ir2
C40-C30-Ir2
C30-C40-Ir1
107.2(5)
110.3(5)
C30-Ir2-Ir1
Ir1-Ir2-C30-C40
Compounds analogous to 1 containing both η2-alkyne
and carbonyl ligands are rare. Recently, the rhodium
compound Rh(CO)(η2-C2Ph2)(η5-C5H5) was prepared from
Rh(SbiPr3)(η2-C2Ph2)(η5-C5H5) upon reaction with CO at
room temperature.11 In the photochemical reaction of
Co(CO)2(η5-C5H5) with C2Ph2 in toluene, a transient
product with an IR peak in the carbonyl region at 1990
cm-1 was assigned to Co(CO)(η2-C2Ph2)(η5-C5H5).12 The
related compound Ir(PiPr3)(η2-C2Ph2)(η5-C5H5) was made
through reaction of IrCl(PR3)(η2-C2R2) with NaCp.13
Also, cationic allyl-alkyne compounds of the form [Ir-
(η3-C3H3)(η2-C2R2)(η5-C5Me5)]+ have been reported.14
Ch a r a cter iza tion of 2. The mass spectra of 2a and
2b are fully consistent with the formulas Ir2(CO)2(C2-
Ph2)(C9H7)2 and Ir2(CO)2(C2Tol2)(C9H7)2, respectively,
and the IR spectrum of each compound in hexane shows
just one CO stretching band at 1961 cm-1. The 1H NMR
spectra of both 2a and 2b (see Table 1 and Figure S-2)
indicate that each indenyl ligand lies in an asymmetric
site but that the respective ligands are equivalent.
Angles between Vectors and Planes (deg)
C1, O1 vs Ir1, Ir2, C30, C40
C2, O2 vs Ir1, Ir2, C30, C40
85.9
81.6
C1, O1 vs C2, O2
172.5
Ta ble 4. Selected Str u ctu r a l Da ta for 3b
Internuclear Distances
Ir1-C1
Ir1-C2
Ir1-C3
Ir1-C4
Ir1-C9
Ir1-C10
Ir1-C20
Ir1-C30
Ir1-C40
2.204(6)
2.202(6)
2.219(6)
2.371(6)
2.358(6)
2.189(5)
2.143(5)
2.109(5)
2.140(6)
C10-C11
C10-C20
C20-C21
C20-C30
C30-C31
C30-C40
C40-C41
C40-C51
1.489(8)
1.445(8)
1.501(8)
1.449(7)
1.498(7)
1.483(7)
1.526(7)
1.518(7)
Bond Angles (deg)
C10-C20-C30
C20-C30-C40
117.9(5)
116.2(5)
C41-C40-C51
107.2(4)
Angles between Vectors and Planesa (deg)
C10, C11 vs C10, C20, C30, C40
C20, C21 vs C10, C20, C30, C40
C30, C31 vs C10, C20, C30, C40
C40, C41 vs C10, C20, C30, C40
+ 8.9
+2.2
-1.8
+8.6
1
The H NMR assignments for 2a and 2b were aided
by homonuclear decoupling experiments as well as by
C40, C51 vs C10, C20, C30, C40
-46.6
1
a H-1H COSY spectrum of 2a (see Figure S-3). This
a
Signs of angles denote orientation of vectors above (+) or below
(-) the mean C10, C20, C30, C40 plane with Ir1 above the plane.
spectroscopic information is consistent with a trans
relationship of the Ir(CO)(η5-C9H7) vertexes in the
expected dimetallocyclobutene molecular core, as ob-
served for a number of related compounds, M2(CO)2(µ-
C2R2)(η5-C5H5)2 (M ) Rh, Ir; R ) CF3, C6F5).15-18 In
comparison, the reaction of Ir(CO)(η2-C8H14)(η5-C9H7)
with HC2Ph provided the dinuclear compound Ir2(CO)2-
(µ2-CdCHPh)(η5-C9H7)2 containing a bridging vinylidene
ligand.5 The reactions of terminal alkynes with mono-
nuclear reagents often lead to vinylidene products.13,19
The molecular structure of 2a , as determined by X-ray
crystallography, is shown in Figure 1; selected struc-
tural data are provided in Table 3. The two Ir atoms
the disappearance of the peak at 1957 cm-1 due to Ir-
(CO)(η2-C8H14)(η5-C9H7) and the initial growth of a new
peak due to 1a at 1969 cm-1 followed by the appearance
of a shoulder due to 2a at 1953 cm-1. Separation of the
reaction mixture by preparative TLC provides light
yellow 1a , orange 2a , and dark yellow 3a , in order of
decreasing Rf. An analogous reaction with ditolylacety-
lene leads to Ir(CO)(η2-C2Tol2)(η5-C9H7) (1b), Ir2(CO)2(µ-
C2Tol2)(η5-C9H7)2 (2b), and Ir(η4-HC4Tol4Ph)(η5-C9H7)
(3b). Similar reactions of Ir(CO)(η2-C8H14)(η5-C9H7)
with C2R2 (R ) Ph, Tol) in toluene, benzene-d6, or
m-xylene also give products 1 and 2, but the identity of
3 depends on the specific reaction solvent, as discussed
below. These reactions are summarized in Scheme 1.
The reaction leading to compounds 1-3 is very
sensitive to reagent concentration and reaction time,
and these parameters can be manipulated to change
product yields. For example, when a 1:10 mixture of
Ir(CO)(η2-C8H14)(η5-C9H7) and C2R2 are present together
at the start of the reaction, significant yields of 2 are
obtained. In contrast, adding Ir(CO)(η2-C8H14)(η5-C9H7)
slowly to a solution of C2R2 at reflux gives only trace
amounts of 2. Furthermore, if the reaction is allowed
to continue after complete consumption of Ir(CO)(η2-
C8H14)(η5-C9H7), higher yields of 3 are obtained but the
yield of 1 decreases. In fact, the direct reactions of
(11) Werner, H.; Heinemann, A.; Windmu¨ller, B.; Steinert, P. Chem.
Ber. 1996, 129, 903.
(12) Lee, W.-S.; Brintzinger, H. H. J . Organomet. Chem. 1977, 127,
93.
(13) Werner, H.; Ho¨hn, A. J . Organomet. Chem. 1984, 272, 105.
(14) Schwiebert, K. E.; Stryker, J . M. Organometallics 1993, 12, 600.
(15) Dickson, R. S.; Kirsch, H. P. Aust. J . Chem. 1972, 25, 2535.
(16) (a) Dickson, R. S.; Kirsch, H. P. J . Organomet. Chem. 1971,
32, C13. (b) Todd, L. J .; Wilkinson, J . R.; Rausch, M. D.; Gardner, S.
A.; Dickson, R. S. J . Organomet. Chem. 1975, 101, 133. (c) Dickson, R.
S.; J ohnson, S. H; Kirsch, H. P.; Lloyd, D. J . Acta Crystallogr. 1977,
B33, 2057. (d) Dickson, R. S.; Mok, C.; Pain, G. J . Organomet. Chem.
1979, 166, 385.
(17) Gardner, S. A; Andrews, P. S.; Rausch, M. D. Inorg. Chem. 1973,
12, 2396.
(18) Corrigan, P. A.; Dickson, R. S. Aust. J . Chem. 1979, 32, 2147.
(19) (a) Bruce, M. I. Chem. Rev. 1991, 91, 197. (b) Bruce, M. I.;
Swincer, A. G. Adv. Organomet. Chem. 1983, 22, 59. (c) Werner, H.
Angew. Chem., Int. Ed. Engl. 1990, 29, 1077. (d) Werner, H. J .
Organomet. Chem. 1994, 475, 45.

4820 Organometallics, Vol. 16, No. 22, 1997
Comstock and Shapley
F igu r e 2. ORTEP diagram of the molecular structure of
3b. The location of the H atom attached to C10 is assumed
(see text).
and -40 °C, as observed by 13C NMR.16b,d The results
were consistent with a pairwise CO bridge-closing and
-opening mechanism coupled with shifts of the Cp rings,
similar to the process proposed for the related compound
Rh2(µ-CO)(CO)2(η5-C5H5)2.22 Scrambling of this type in
2a and 2b would lead to exchange of the H1 and H3
protons on the indenyl ligands, as observed for the
related compound Ir2(µ-CO)(CO)2(η5-C9H7)2.1 This is not
observed for 2a or 2b, presumably due to the difficulty
of forming a triply bridged intermediate in the case of
a bulky diarylacetylene.
Ch a r a cter iza tion of 3. The mass spectra of 3a and
3b contain molecular ions at m/ z 742 and 798, respec-
tively, with isotope patterns consistent with just one Ir
atom. The mass difference clearly indicates the incor-
poration of 2 equiv of alkyne in the molecule, and the
total mass suggests 1 equiv of benzene as well, resulting
in a formula of Ir(C2R2)2(C6H6)(C9H7)2. Further support
for a formula incorporating 1 equiv of solvent is provided
by the results of analogous reactions in toluene and
m-xylene, leading to 3d , 3e, and 3f, with masses clearly
reflecting the expected number of methyl groups. The
reaction with ditolylacetylene also was conducted in
benzene-d6; the 1H NMR spectrum of resulting 3c is
nearly identical to that of 3b but lacks several multip-
lets in the arene region due to the coordinated “benzene”
moiety. Nevertheless, the form of benzene incorporation
into the molecule has only been defined by X-ray
crystallography.
The molecular structure of 3b is depicted in Figure 2
and selected structural details are provided in Table 4.
The molecule contains an η5-indenyl ligand and an η4-
1-phenyl-1,2,3,4-tetratolyl-1,3-butadiene ligand. Dis-
tances from the iridium center to the four carbons in
the butadiene backbone, C10, C20, C30, and C40, are
2.189(5), 2.143(5), 2.109(5), and 2.140(6) Å, respectively.
The bond vectors, C10-C11, C20-C21, C30-C31, and
C40-C41 for the four tolyl substituents are all within
10° of being coplanar with the C10, C20, C30, C40 plane,
but the C40-C51 vector for the phenyl substituent is
displaced 46.6° below the plane (with the iridium atom
defined as above the plane). An analogous position is
presumed for the hydrogen atom attached to C10. The
C5 ring of the indenyl ligand attached to Ir1 makes an
F igu r e 1. ORTEP diagram of the molecular structure of
2a .
and the two alkyne carbon atoms form a nearly planar
dimetallacyclobutene core; the C30-C40 vector is slightly
twisted (ca. 5°) with respect to the Ir1-Ir2 vector. The
CO ligands are nearly perpendicular to the Ir1, Ir2, C30,
C40 mean plane and are nearly antiparallel to each
other. The indenyl ligands take positions opposite the
carbonyl ligands at each iridium vertex. The bond
distances and angular orientations are very similar to
those determined for the analogous compounds Ir2(CO)2-
(µ-C6H4)(η5-C5H5)2 (Ir-Ir ) 2.7166(2) Å, Ir-C ) 2.045-
(3) Å, and C-C ) 1.386(3) Å)20 and trans-Rh2(CO)2(µ-
CF3C2CF3)(η5-C5H5)2 (Rh-Rh ) 2.682(1) Å and Rh-C
) 2.054(10), 2.031(10) Å).16c
Although the two Cp ligands in trans-Rh2(CO)2(µ-
CF3C2CF3)(η5-C5H5)2 and Ir2(CO)2(µ-C6H4)(η5-C5H5)2 are
related by (noncrystallographic) 2-fold axes, the two
indenyl ligands in 2a are not. They are both inclined
at approximately 50° with respect to the Ir1, Ir2, C30,
C40 mean plane, but they are not related by symmetry
in the solid state. The long axis of the indenyl ligand
attached to Ir1 is “horizontal” with respect to the Ir1-
Ir2 vector while that for the ligand attached to Ir2 is
“vertical”. In solution, however, only one set of indenyl
resonances is observed by 1H NMR, consistent with free
rotation of the η5-C9H7 ligands. The structural details
of indenyl ligand bonding can be described by the slip
distortion parameter (∆), the fold angle, and the hinge
angle.21 For the indenyl ligands attached to Ir1 and Ir2
in 2a , these parameters have the values ∆ ) 0.09 and
0.13 Å, fold angles ) 4.58° and 6.15°, and hinge angles
) 3.25° and 6.26°, respectively, which are fully consis-
tent with their characterization as η5-indenyl ligands.
The trans isomer of Rh2(CO)2(µ-CF3C2CF3)(η5-C5H5)2
exhibited CO site exchange between room temperature
(20) Rausch, M. D.; Gastinger, R. G.; Gardner, S. A.; Brown, R. K.;
Wood, J . S. J . Am. Chem. Soc. 1977, 99, 7870.
(21) (a) Faller, J . W.; Crabtree, R. H.; Habib, A. Organometallics
1985, 4, 929. (b) Baker, R. T.; Tulip, T. H. Organometallics 1986, 5,
839. (c) Donovan, B. T.; Hughes, R. P.; Trujillo, H. A.; Rheingold, A. L.
Organometallics 1992, 11, 64. (d) Kakkar, A. K.; Taylor, N. J .;
Calabrese, J . C.; Nugent, W. A.; Roe, D. C.; Connaway, E. A.; Marder,
T. B. J . Chem. Soc., Chem. Commun. 1989, 990.
(22) (a) Evans, J .; J ohnson, B. F. G.; Lewis, J .; Norton, J . R. J . Chem.
Soc., Chem. Commun. 1973, 79. (b) Evans, J .; J ohnson, B. F. G.; Lewis,
J .; Matheson, T. W.; Norton, J . R. J . Chem. Soc., Dalton Trans. 1978,
626.

Synthesis of Ir(CO)(η2-C2R2)(η5-C9H7)
Organometallics, Vol. 16, No. 22, 1997 4821
F igu r e 3. Partial 1H NMR spectrum of 3b recorded at 750
MHz. Assignment of the phenyl and indenyl ring signals
derives in part from correlation data shown in Figure 4.
F igu r e 5. 1H-13C heteronuclear correlation spectrum of
3b in acetone-d6 at room temperature. The inset shows
data from the corresponding spectrum of 3c.
are observed in this portion of the spectrum between
room temperature and -50 °C, in contrast to the
situation for the tolyl ring signals (vide infra).
From Figures 3 and 4 one can also readily identify
the signals for the protons on the indenyl ring. An
individual 1H multiplet at δ 7.59 (H4) is correlated to a
tightly coupled 3H pattern near δ 7.4 (H5-H7). Ap-
propriate cross peaks are also observed to confirm the
assignment of the indenyl H1, H2, and H3 protons.
The tolyl ring resonances fall into two groups. One
group consists of four 2H doublets that are pairwise
correlated (labeled TolA and TolB in Figure 4) and show
no temperature dependence. Each correlated pair is
assigned to the (apparently equivalent) ortho and meta
protons on a rapidly rotating tolyl ring. The other group
is a set of eight 1H doublets distributed over the range
δ 6.9-5.9 that show pairwise correlations (labeled Tol′a-
Tol′d in Figure 4) and broaden as the temperature is
raised from -50 °C to room temperature. Each of these
correlated pairs is assigned to an ortho-meta proton
pair on one side of a tolyl ring that is rotating slowly at
-50 °C. The onset of higher rotation rates at higher
temperatures will begin to cause observable exchange
between ortho-ortho and meta-meta pairs on each ring.
These two groups of tolyl rings presumably correspond
to substituents on the two general types of positions on
the butadiene ligand backbone, namely, at the terminal
positions (C1, C4) or the inner positions (C2, C3). Un-
fortunately, it is not obvious from the crystal structure
of 3b (see Figure 2) which of the corresponding positions
C10, C40 or C20, C30 might represent the more crowded
sites.
F igu r e 4. 1H-1H COSY spectrum of 3b in acetone-d6 at
-50 °C. See text for explanation of labels. The peak marked
with an asterisk is due to CH2Cl2.
angle of 16.69(35)° with the C4 backbone of the buta-
diene ligand. The indenyl ligand’s bonding parameters
are ∆ ) 0.153 Å, fold angle ) 8.93°, and hinge angle )
7.03°, which are similar to those observed for 2a and
related compounds.1,21
The 1H NMR spectrum of compound 3b has been
investigated in detail. Figure 3 provides a portion of
the spectrum recorded at 750 MHz, and Figure 4 shows
1
the H-1H COSY spectrum at -50 °C. The resonances
for the phenyl group are readily identified by their
absence in the spectrum of C6D6-derived 3c. The 1H
doublet at lowest field is assigned to an ortho proton
(labeled a), and a cross peak connects this peak to a 1H
triplet assigned to a meta proton (labeled b). This meta
proton is coupled to a 2H multiplet that contains peaks
for both the para proton and the other ortho proton
(labeled c and e). Finally, coupling between this mul-
tiplet and the 1H triplet at higher field identifies the
latter as the other meta proton (labeled d). It is
noteworthy that separate resonances are seen for both
ortho as well as both meta positions on the phenyl ring.
This is consistent with the asymmetry of the molecule
and, therefore, gives no indication whether ring rotation
is strongly hindered. No temperature-dependent effects
The singlet resonance expected for the single proton
attached to one terminal carbon of the butadiene ligand
in 3b does not appear in the lower field region shown
in Figures 3 and 4. However, 1H-13C heteronuclear
correlation spectra unambiguously establish that a 1H
singlet at the higher field position of δ 2.47 is due to
this proton. As shown in Figure 5, the singlet at this
1
position in the H spectrum is correlated with a signal
at δ 51.7 in the 13C spectrum. Most definitively,
however, this carbon signal becomes a 1:1:1 triplet (J
) 24.3 Hz) in the spectrum of 3c, proving that it is due

4822 Organometallics, Vol. 16, No. 22, 1997
Comstock and Shapley
Sch em e 2
to a C-D moiety, with the deuterium atom derived from
C6D6. High-field shifts for the signals of protons or
carbons in ligands π-bonded to Ir(I) are not uncommon;5
for comparison, the proton and carbon signals for the
analogous position in the diene moiety of Ir(η5-C5H5)-
(η4-C5H6) occur at δ 3.13 and δ 23.9, respectively.23
The reaction of Ir(CO)(η2-C8H14)(η5-C9H7) with C2Ph2
in toluene at reflux provided 3d . The 1H NMR spectrum
contained more than one set of indenyl H1-H3 proton
resonances. Also, three peaks in the tolyl methyl region
were observed, suggesting the presence of isomeric
compounds incorporating a toluene molecule attached
at ring positions ortho, meta, and para to the methyl
group. The H NMR spectra of products 3f and 3e also
were cluttered with what appeared to be a mixture of
isomeric products.
F or m a tion of 3. The formation of 3 requires the loss
of a carbonyl ligand, linkage of two alkyne units and
the incorporation of one arene solvent molecule. The
timing of these steps is a key consideration.
The incorporation of the arene solvents in compounds
3a -f requires the formal CH activation of the solvents
and possibly proceeds through an intermediate of the
form IrH(aryl)(CO)(η5-C9H7). The analogous compound,
IrH(C6H5)(CO)(η5-C5H5), was observed spectroscopically
in the reaction forming Ir2(CO)2(µ-C6H4)(η5-C5H5)2.20
Also, the photolysis of Ir(CO)2(η5-C5Me5) in benzene
produced IrH(C6H5)(CO)(η5-C5Me5).24 Furthermore, the
reactions of Ir(H)(Me)(PMe3)(η5-C9H7) with RC2R′ pro-
vided the vinyl products, Ir(Me)(CRdCHR′)(PMe3)(η5-
C9H7),25 and kinetics studies were consistent with a
mechanism involving reversible coordination of the
alkyne followed by hydride migration, concurrent with
η5 to η3 and η3 to η5 hapticity changes in the indenyl
ligand. However, the reaction of 1 with excess acetylene
leads to 3 in high yields. Therefore, the activation of
the solvent and the formation of 3 probably proceeds
through an alkyne-containing intermediate such as IrH-
(aryl)(η2-C2R2)(η5-C9H7). This idea leads to the set of
steps proposed in Scheme 2, which includes the follow-
ing: (i) Coordination of benzene in an η2 fashion26 to 1
with an indenyl η5-η3 ring slippage gives A, which is
followed by oxidative addition, extrusion of CO, and
subsequent η3-η5 recoordination, leading to the alkyne
phenyl hydride product B. (ii) Insertion of the alkyne
into the Ir-H bond and incorporation of another mol-
ecule of C2R2 would lead to a vinyl alkyne intermediate
C, again, probably accompanied by indenyl slippage
upon alkyne coordination followed by indenyl recoordi-
nation after insertion. (iii) Subsequent insertion of the
alkyne into the Ir-vinyl bond gives the σ, π-vinyl olefin
species D, and reductive elimination of the vinyl group
with the Ph ligand provides the η4-diene compound 3.
Intermediates similar to D have been suggested for
the reactions of [Ir(η2-MeC2Me)(η3-C3H3)(η5-C5Me5)+]
with alkynes, in which the coupling of the allyl ligand
and two alkyne units led to compounds containing η5-
cycloheptadienyl ligands.27 Also, the related insertion
of 2-butyne into an intermediate iridacyclopentene
complex has been proposed.28 An alternative to the
mechanism proposed in Scheme 2 could involve coordi-
nation of a second alkyne to 1 and subsequent CO loss
before C-H bond oxidative addition. However, we
observed none of the side products expected from such
a metallocyclopentadiene pathway.
1
The reactions of acetylenes with M(CO)2(η5-L) (M )
Co, Rh, Ir; L ) C5H5, L ) C5Me5) have often led to
organometallic compounds containing oligomerized acety-
(26) For examples, see: (a) Selmeczy, A. D.; J ones, W. D.; Osman,
R.; Perutz, R. N. Organometallics 1995, 14, 5677. (b) J ones, W. D.;
Feher, F. J . J . Am. Chem. Soc. 1986, 108, 4814. (c) Chin, R. M.; Dong,
L.; Duckett, S. B.; Partridge, M. G.; J ones, W. D.; Perutz, R. N. J . Am.
Chem. Soc. 1993, 115, 7685. (d) J ones, W. D.; Feher, F. J . J . Am. Chem.
Soc. 1984, 106, 1650.
(23) Szajek, L. P.; Shapley, J . R. Organometallics 1991, 10, 2512.
(24) Hoyano, J . K.; Graham, W. A. G. J . Am. Chem. Soc. 1982, 104,
3723.
(27) Schwiebert, K. E.; Stryker, J . M. J . Am. Chem. Soc. 1995, 117,
8275.
(28) McGhee, W. D.; Bergman, R. G. J . Am. Chem. Soc. 1988, 110,
4246.
(25) Foo, T.; Bergman, R. G. Organometallics 1992, 11, 1811.

Synthesis of Ir(CO)(η2-C2R2)(η5-C9H7)
Organometallics, Vol. 16, No. 22, 1997 4823
lene units as ligands.29 For example, the reactions of
M(CO)2(η5-C5Me5) (M ) Co, Rh, Ir) with C2R2 (R ) Me,
CF3) provided a variety of interesting products.30 For
M ) Co or Rh, the cyclopentadienone compounds M(η4-
C4R4CO)(η5-C5Me5) were major products and the minor
products observed were mononuclear complexes con-
taining η4-hexasubstituted benzene ligands or dinuclear
compounds containing bridging pentadienone or hexa-
1,5-diene-3,4-dione ligands. The reaction of Ir(CO)2(η5-
C5Me5) with CF3C2CF3 led to a mononuclear compound
containing a metallocyclobutenone unit as well as a
dinuclear product containing a metallocyclopentadiene
unit. Intriguingly, however, the reaction of Rh(CO)2-
(η5-C5H5) with C2Ph2 in toluene provided a compound
with the formula Rh(C2Ph2)2(C7H8)(C5H5), as deter-
mined by elemental analysis and mass spectrometry.17
The 1H NMR spectrum of this compound contained
several singlets in the methyl region, apparently due
to various tolyl isomers, so that it now appears that this
product may be analogous to compound 3, specifically
3d , discussed here.
Alternatively, further reaction of 1 with C2R2 as well
as one molecule of solvent (e.g., benzene) gave Ir(η4-
HC4R4R′)(η5-C9H7) (3a , R ) Ph, R′ ) Ph; 3b). The
identities of 3a -f were probed by mass spectrometry,
confirming the proposed molecular formulas, Ir(η4-
C2R2)2(arene)(η5-C9H7), while the molecular connectivity
1
of 3a , 3b, and 3c was examined by H-1H COSY and
1H-13C HETCOR NMR experiments. The structure of
3b, determined by X-ray diffraction, contains a 1-phen-
yl-1,2,3,4-tetratolyl-1,3-butadiene ligand formed through
both alkyne coupling and CH bond activation of the
benzene solvent.
Ack n ow led gm en t. This research was supported by
National Science Foundation Grant No. CHE 94-14217.
M.C.C. thanks the Department of Chemistry for a
fellowship funded by the Lubrizol Corporation. NMR
spectra were obtained using instruments in the Varian
Oxford Instrument Center for Excellence in NMR
Laboratory in the School of Chemical Sciences; external
funding for this instrumentation was obtained from the
Keck Foundation, NIH, and NSF. We thank VOICE
NMR Lab Director Dr. Vera Mainz for collecting key
spectral data. The purchase of the Siemens Platform/
CCD diffractometer by the School of Chemical Sciences
was supported by National Science Foundation Grant
No. CHE 95-03145. We thank Drs. S. R. Wilson and T.
Prussak-Wieckowska for collecting X-ray diffraction
data for 2a and 3b.
Con clu sion s
The mononuclear alkyne compounds Ir(CO)(η2-C2R2)-
(η5-C9H7) (1a , R ) Ph; 1b, R ) Tol) have been prepared
through the reaction of Ir(CO)(η2-C8H14)(η5-C9H7) with
excess C2R2. Subsequent reaction of 1 with Ir(CO)(η2-
C8H14)(η5-C9H7) formed the dinuclear compounds Ir2-
(CO)2(µ-C2R2)(η5-C9H7)2 (2a , R ) Ph; 2b, R ) Tol), and
the structure of 2a was examined by X-ray diffraction.
Su p p or tin g In for m a tion Ava ila ble: Complete tables of
(29) (a) Dickson, R. S. Organometallic Chemistry of Rhodium and
Iridium; Academic: New York, 1983; Chapter 6. (b) Hughes, R. P. In
Comprehensive Organometallic Chemistry I; Wilkinson, G., Stone, F.
G. A., Abel, E. W., Eds.; Pergamon: New York, 1982; Vol. 5, Chapter
35, pp 440-444 and 456-485.
atom coordinates, anisotropic displacement parameters, and
1
distances and angles for both 2a and 3b and H NMR spectra
of 2a and 2b (12 pages). Ordering information is given on any
current masthead page.
(30) Corrigan, P. A.; Dickson, R. S.; Fallon, G. D.; Michel, L. J .; Mok,
C. Aust. J . Chem. 1978, 31, 1937.
OM970579I