Alkylation of iridium via tandem carbon-hydrogen bond activation/decarbonylation of aldehydes. Access to complexes with tertiary and highly hindered metal-carbon bonds

Article abstract of DOI:10.1021/om9910064

Reactions between Cp*(PMe₃)Ir(Me)OTf (1) and aldehydes (RCHO) proceed with high selectivity to give the hydrocarbyl carbonyl salts [Cp*(PMe₃)Ir(R)(CO)][OTf] (R = Me (2), Et (3), n-Pr (4), c-Pr (5), Ph (6), 1-ethylpropyl (7), p-tolyl (8), mesityl (9), 2-(Z)-1-phenylpropenyl (10), vinyl (13), t-Bu (14), 1-adamantyl (17)). This tandem C-H bond activation/decarbonylation reaction provides access to the first isolated tertiary alkyl complexes of iridium. X-ray diffraction studies were performed on mesityl complex 9, tert-butyl derivative 15, and 1-adamantyl compound 18. Decarbonylation of cyclopropyl complex 5 results in irreversible opening of the cyclopropyl ring. This reaction has provided useful information concerning the mechanism of C-H activation of cyclopropane by 1. Hydride reduction of the p-tolyl carbonyl salt 8 has provided an example of a rare transition-metal formyl complex, Cp*-(PMe₃)Ir(p-tolyl)(CHO) (28).

Full text of DOI:10.1021/om9910064

2130
Organometallics 2000, 19, 2130-2143
Alk yla tion of Ir id iu m via Ta n d em Ca r bon -Hyd r ogen
Bon d Activa tion /Deca r bon yla tion of Ald eh yd es. Access to
Com p lexes w ith Ter tia r y a n d High ly Hin d er ed
Meta l-Ca r bon Bon d s
Peter J . Alaimo, Bruce A. Arndtsen, and Robert G. Bergman*
Department of Chemistry, University of California, and Chemical Sciences Division,
Lawrence Berkeley National Laboratory, Berkeley, California 94720
Received December 17, 1999
Reactions between Cp*(PMe3)Ir(Me)OTf (1) and aldehydes (RCHO) proceed with high
selectivity to give the hydrocarbyl carbonyl salts [Cp*(PMe3)Ir(R)(CO)][OTf] (R ) Me (2), Et
(3), n-Pr (4), c-Pr (5), Ph (6), 1-ethylpropyl (7), p-tolyl (8), mesityl (9), 2-(Z)-1-phenylpropenyl
(10), vinyl (13), t-Bu (14), 1-adamantyl (17)). This tandem C-H bond activation/decarbon-
ylation reaction provides access to the first isolated tertiary alkyl complexes of iridium. X-ray
diffraction studies were performed on mesityl complex 9, tert-butyl derivative 15, and
1-adamantyl compound 18. Decarbonylation of cyclopropyl complex 5 results in irreversible
opening of the cyclopropyl ring. This reaction has provided useful information concerning
the mechanism of C-H activation of cyclopropane by 1. Hydride reduction of the p-tolyl
carbonyl salt 8 has provided an example of a rare transition-metal formyl complex, Cp*-
(PMe3)Ir(p-tolyl)(CHO) (28).
In tr od u ction
(PMe3)Ir(Me)]+.16 In addition to our initial studies aimed
at exploring the scope and limitations of reactions of 1
(and its BArf salt) with organic substrates,14,15,17 we
have focused our efforts on the utilization of this
interesting class of reactions for the synthesis of unusual
organometallic complexes of structural and mechanistic
consequence. For example, recent work in our group has
shown that 1 can be used to access iridium Fischer
carbene and carbyne complexes.18,19 In the present
report we describe the synthesis of tertiary alkyl and
cyclopropyl substituted iridium complexes by a tandem
C-H activation/carbonyl migratory deinsertion reaction
of triflate complex 1 with aldehydes, as well as further
derivatization reactions of the products of the tandem
reaction.20
Significant advances have been made since the initial
discovery of transition-metal complexes that are capable
of intermolecular cleavage of the carbon-hydrogen
bonds in saturated hydrocarbons.1-13 We recently dis-
covered a stoichiometric system that thermally activates
the C-H bonds of methane, as well as other hydrocar-
bons and simple organic molecules, at unprecedentedly
low temperatures.14,15 This system utilizes the iridium-
(III) complexes Cp*(PMe3)Ir(Me)OTf (1) and [Cp*(PMe3)-
Ir(Me)(CH2Cl2)][BArf] (BArf ) B(3,5-C6H3(CF3)2)4-) as
precursors of the highly reactive cationic species [Cp*-
(1) Hill, C. L. Activation and Functionalization of Alkanes; Wiley:
New York, 1989; pp 372. For recent reviews on C-H activation see
refs 2-9.
(2) Stahl, S. S.; Labinger, J . A.; Bercaw, J . E. Angew. Chem., Int.
Ed. Engl. 1998, 37, 2181-2192.
(3) Sen, A. Acc. Chem. Res. 1998, 31, 550-557.
(4) Shilov, A. E.; Shul’pin, G. B. Chem. Rev. 1997, 97, 2879-2932.
(5) Lohrenz, J . C. W.; J acobsen, H. Angew. Chem., Int. Ed. Engl.
1996, 35, 1305-1307.
Resu lts
Rea ction of 1 w ith Alip h a tic a n d Ar om a tic Al-
d eh yd es: Syn th esis of Ca tion ic Hyd r oca r byl Ca r -
bon yl Com p lexes. Addition of 1 equiv of aldehyde
(RCHO) to dichloromethane solutions of Cp*(PMe3)Ir-
(Me)OTf (1) at room temperature results in rapid
evolution of methane and the formation of the cationic
hydrocarbyl carbonyl complexes [Cp*(PMe3)Ir(R)(CO)]-
[OTf] (R ) Me (2), Et (3), n-Pr (4), c-Pr (5), Ph (6),
(6) Sen, A. In Applied Homogeneous Catalysis with Organometallic
Compounds: A Comprehensive Handbook in Two Volumes; Cornils,
B., Herrmann, W. A., Eds.; Wiley-VCH: New York, 1996; Vol. 2, pp
1081-1092, and references therein.
(7) Schneider, J . J . Angew. Chem., Int. Ed. Engl. 1996, 35, 1069-
1075.
(8) Arndtsen, B. A.; Bergman, R. G.; Mobley, T. A.; Peterson, T. H.
Acc. Chem. Res. 1995, 28, 154-162.
(9) Schro¨der, D.; Schwarz, H. Angew. Chem., Int. Ed. Engl. 1995,
34, 1973-1995.
(10) Periana, R. A.; Taube, D. J .; Gamble, S.; Taube, H.; Satoh, T.;
Fujii, H. Science 1998, 280, 560-564.
(16) Adamson, D. R.; Arndtsen, B. A.; Bergman, R. G. Manuscript
in preparation.
(11) Periana, R. A.; Taube, D. J .; Evitt, E. R.; Loffler, D. G.;
Wentrcek, P. R.; Voss, G.; Masuda, T. Science 1993, 259, 340-343.
(12) J ohansson, L.; Ryan, O. B.; Tilset, M. J . Am. Chem. Soc. 1999,
121, 1974-1975.
(17) Arndtsen, B. A.; Bergman, R. G. J . Organomet. Chem. 1995,
504, 143-146.
(18) Luecke, H. F.; Arndtsen, B. A.; Burger, P.; Bergman, R. G. J .
Am. Chem. Soc. 1996, 118, 2517-2518.
(13) Mylvaganam, K.; Bacskay, G. B.; Hush, N. S. J . Am. Chem.
Soc. 1999, 121, 4633-4639.
(14) Arndtsen, B. A.; Bergman, R. G. Science 1995, 270, 1970-1973.
(15) Burger, P.; Bergman, R. G. J . Am. Chem. Soc. 1993, 115,
10462-10463.
(19) Luecke, H. F.; Bergman, R. G. J . Am. Chem. Soc. 1998, 120,
11008-11009.
(20) A portion of the work described here has been reported in
preliminary form: Alaimo, P. J .; Arndtsen, B. A.; Bergman, R. G. J .
Am. Chem. Soc. 1997, 119, 5269-5270.
10.1021/om9910064 CCC: $19.00 © 2000 American Chemical Society
Publication on Web 04/29/2000

Alkylation of Iridium
Organometallics, Vol. 19, No. 11, 2000 2131
Ta ble 1. Selected Bon d Dista n ces (Å) a n d Bon d
An gles (d eg) for [Cp *(P Me3)Ir (m esityl)(CO)][OTf]
(9)
(a) Bond Distances
Ir(1)-C(1)
1.860(5)
2.154(5)
2.333(1)
1.9018(2)
1.149(6)
Ir(1)-C(14)
Ir(1)-C(15)
Ir(1)-C(16)
Ir(1)-C(17)
Ir(1)-C(18)
2.262(4)
2.316(5)
2.298(5)
2.246(4)
2.253(4)
Ir(1)-C(2)
Ir(1)-P(1)
Ir(1)-Cp* centroid
C(1)-O(1)
(b) Bond Angles
P(1)-Ir(1)-C(1) 84.8(2) C(2)-Ir(1)-Cp* centroid 123.5(1)
P(1)-Ir(1)-C(2) 92.4(1) P(1)-Ir(1)-Cp* centroid 130.15(3)
C(1)-Ir(1)-C(2) 92.4(2)
Sch em e 1
F igu r e 1. ORTEP plot of the solid-state molecular struc-
ture of the major component of the cationic portion of [Cp*-
(PMe3)Ir(mesityl)(CO)][OTf] (9). Thermal ellipsoids are
shown at the 50% probability level. Hydrogen atoms are
omitted for clarity.
1-ethylpropyl (7), p-tolyl (8), mesityl (9), 2-(Z)-1-phen-
ylpropenyl (10)) (eq 1). Complexes 2-10 exhibit similar
ligand) bond length was found to be 2.154(5) Å, the Ir-
(1)-P(1) bond length is 2.333(1) Å, the Ir(1)-C(1)
(carbonyl ligand) is 1.860(5) Å, and the Ir(1)-Cp*
(centroid) bond length is 1.9018(2) Å. All of these bond
lengths are normal. The data collection and refinement
parameters are listed in the Experimental Section in
Table 4, and a listing of selected bond distances and
angles is located in Table 1.
The reactions between 1 and aldehydes are extremely
rapid and clean. Monitoring these reactions at room
temperature by 1H and 31P{1H} NMR spectroscopy
revealed no intermediates or side products; however,
monitoring the reaction between benzaldehyde and 1
at low temperature allowed for direct observation of a
new species. Benzaldehyde (R ) Ph) and a dichlo-
romethane-d2 solution of 1 were combined at -78 °C in
an NMR tube, and the tube was placed in a precooled
(-80 °C) NMR spectrometer probe. Monitoring the
reaction mixture spectroscopically showed the formation
of a new complex. This complex is assigned as the η1-
(O)-bound aldehyde adduct22 (11) of 1 (Scheme 1), on
the basis of the 1H and 31P{1H} NMR spectroscopic data;
a new aldehyde resonance was observed in the 1H NMR
spectrum at 9.50 ppm (cf. δ 10.01 for free benzaldehyde).
This small change in the aldehydic proton resonance is
typical of η1(O)-bound aldehyde adducts. The aldehydic
proton resonance for adducts that are π-bound are
typically shifted farther upfield (6-7 ppm).23 The new
aldehydic proton resonance was accompanied by new
resonances for the metal-bound Cp* ligand, the tri-
methylphosphine ligand, and the iridium-bound methyl
group. When the probe of the NMR spectrometer was
warmed to -60 °C, the resonances for 11 disappeared
(t1/2 ≈ 10 min) and were replaced by resonances corre-
sponding to 6 and methane.
1H, 19F, and 31P{1H} NMR spectra as well as νCO
infrared stretching frequencies. In the H NMR spectra
1
of 2-10 the resonances for the Cp* ligands appear at δ
1.94-2.08 (4J P-H ) 2.0-2.4 Hz) and the trimethylphos-
phine protons resonate at δ 1.69-1.86 (2J P-H ) 10.8-
11.2 Hz). The 31P{1H} NMR resonances of complexes
2-8 and 10 appear at δ -32.9 to -35.2, while the
phosphorus nucleus for the sterically bulky mesityl
complex 9 resonates further upfield at δ -43.9. These
complexes absorb at 1997-2035 cm-1 (νCO) in their
infrared spectra. These stretching frequencies are nor-
mal for terminal carbon monoxide ligands.21
A single-crystal X-ray diffraction study was performed
on mesityl complex 9. Colorless block-shaped crystals
were grown by vapor diffusion of pentane into a dichlo-
romethane solution of 9 at -35 °C over 1 week. Details
of the solution of the structure are given in the Experi-
mental Section. The cationic portion of 9 was disordered;
successful modeling of the data was achieved with 5%
occupancy of Ir(2) and P(2). The bonding and molecular
geometry of the major component of the cationic portion
of 9 are illustrated in Figure 1. The Ir(1)-C(2) (mesityl
(22) Aldehydes are known to bind to transition metals η1 through
oxygen23,27-29 and η2 through the CdO double bond.23,27-30
(23) Lenges, C. P.; Brookhart, M.; White, P. S. Angew. Chem., Int.
Ed. Engl. 1999, 38, 552-555.
(21) Collman, J . P.; Hegedus, L. S.; Norton, J . R.; Finke, R. G.
Applications of Organotransition Metal Chemistry; University Science
Books: Mill Valley, CA, 1987; pp 110-117.

2132 Organometallics, Vol. 19, No. 11, 2000
Alaimo et al.
Sch em e 2
Sch em e 3
atom, and 12 exhibits a strong carbonyl stretch in the
infrared spectrum at νCO 1677 cm-1. Finally, the 1H
NMR spectrum of 12 exhibits a signal for the iridium-
bound methyl group which appears as a doublet (3J P-H
) 6.4 Hz) at 0.81 ppm (cf. 0.92 ppm for 1), indicating
that loss of methane has not occurred. Complex 12 was
found to be the kinetic product of the reaction, as
subsequent thermolysis in CD2Cl2 (75 °C, 24 h) afforded
the expected vinyl carbonyl product 13 in 57% isolated
yield (Scheme 2). Vinyl complex 13 shows no unusual
spectroscopic features.
Syn th esis of Ter tia r y Alk yl Su bstitu ted Ir id iu m
Com p lexes. The general reaction sequence illustrated
in eq 1 also provides a synthetic route to tertiary alkyl
complexes of iridium. For example, addition of 1 equiv
of 2,2-dimethylpropanal (t-BuCHO) to 1 provided the
tert-butyl carbonyl triflate salt 14 (Scheme 3). Multiple
attempts to grow crystals suitable for X-ray diffraction
were unsuccessful. Therefore, we decided to exchange
the triflate anion for an anion of increased crystallinity.
Subjecting 14 to anion metathesis using sodium tet-
raphenylborate cleanly afforded [Cp*(PMe3)Ir(t-Bu)-
(CO)][BPh4] (15).
An X-ray diffraction study of 15 was undertaken,
since we were aware of no isolated iridium complexes
bearing tertiary alkyl ligands. Pale columnar crystals
of 15 were grown from a toluene/CH2Cl2 solution at -30
°C over 2 weeks. The bonding and molecular geometry
of the major component of the cationic portion of 15 is
illustrated in Figure 2. Solution of the structure was
complicated by substantial disorder and twinning.
Details of the structure analysis are given in the
Experimental Section. Although the nondisordered mol-
ecule shows the expected three-legged piano-stool coor-
dination geometry, care should be exercised in the
interpretation of the geometric data. The data collection
and refinement parameters are provided in Table 4, and
a listing of selected bond distances and angles is located
in Table 2.
Adamantane-1-carboxaldehyde (16), prepared from
adamantylmethanol via a Swern oxidation32 in 59%
yield, reacts cleanly with 1 to give the 1-adamantyl
triflate salt 17 (Scheme 4) in 72% isolated yield. Because
of the difficulty in growing X-ray-quality crystals, we
again decided to exchange the triflate anion for another
anion, this time using BArf. Anion metathesis was
performed by the addition of NaBArf to 17 in dichlo-
To confirm that the methane byproduct produced in
the reactions of 1 with aldehydes is a result of activation
of the aldehydic C-H bond, the reaction of 1 with
acetaldehyde-1-d (eq 2) was investigated. This produced
CH CDO8
3
Cp*(PMe3)Ir(Me)(OTf)
CH2Cl2
1
[Cp(PMe )Ir(Me)(CO)][OTf]
+ CH3D (2)
3
2
exclusively CH3D (no CH4 was observed) and 2 (deter-
1
mined by H NMR spectroscopy). This experiment also
eliminates the possibility that C-H activation in these
reactions proceeds through a cyclometalated intermedi-
ate, as has been suggested24,25 and ruled out in other
studies as well.26
Addition of acrolein (CH2dCHCHO) to a CD2Cl2
solution of 1 at room temperature did not directly form
the expected vinyl carbonyl complex (13) (Scheme 2).
Instead, coordination of acrolein to iridium starting
material 1 produced π-complex 12 in 63% isolated yield.
A new aldehydic proton resonance is observed in the
1H NMR spectrum of 12 at δ 8.23 (cf. δ 9.55 for free
acrolein). It appears as a broad doublet, and the
resonance for the carbon atom of the carbonyl moiety
appears at δ 191.9 (cf. δ 194.4 for free acrolein).
1
Additionally, the alkene resonances in the H and 13C-
{1H} NMR spectrum are shifted significantly upfield
relative to those of free acrolein. These data suggest that
12 is an alkene adduct, not a carbonyl (either η1 or η2)
adduct.23,27-31 In agreement with this formulation,
coupling is also observed in complex 12 between all
three vinylic protons and the iridium-bound phosphorus
(24) Hinderling, C.; Feichtinger, D.; Plattner, D. A.; Chen, P. J . Am.
Chem. Soc. 1997, 119, 10793-10804.
(25) Hinderling, C.; Plattner, D. A.; Chen, P. Angew. Chem., Int.
Ed. Engl. 1997, 36, 243-244.
(26) Luecke, H. F.; Bergman, R. G. J . Am. Chem. Soc. 1997, 119,
11538-11539.
(27) Wang, Y.; Agbossou, F.; Dalton, D. M.; Liu, Y. M.; Arif, A. M.;
Gladysz, J . A. Organometallics 1993, 12, 2699-2713.
(28) Gladysz, J . A.; Boone, B. J . Angew. Chem., Int. Ed. Engl. 1997,
36, 551-583.
(29) Cicero, R. L.; Protasiewicz, J . D. Organometallics 1995, 14,
4792-4798.
(30) Helberg, L. E.; Gunnoe, T. B.; Brooks, B. C.; Sabat, M.; Harman,
W. D. Organometallics 1999, 18, 573-581.
(31) Song, J . S.; Szalda, D. J .; Bullock, R. M. Inorg. Chim. Acta 1997,
259, 161-172.
(32) Mancuso, A. J .; Swern, D. Synthesis 1981, 165-185.

Alkylation of Iridium
Organometallics, Vol. 19, No. 11, 2000 2133
F igu r e 3. ORTEP plot of the solid-state molecular struc-
ture of the major component of the cationic portion of [Cp*-
(PMe3)Ir(1-adamantyl)(CO)][BArf] (18). Thermal ellipsoids
are shown at the 50% probability level. Some of the
hydrogen atoms are omitted for clarity.
F igu r e 2. ORTEP plot of the solid-state molecular struc-
ture of the major component of the cationic portion of [Cp*-
(PMe3)Ir(t-Bu)(CO)][BPh4] (15). Thermal ellipsoids are
shown at the 50% probability level.
Ta ble 3. Selected Bon d Dista n ces (Å) a n d Bon d
An gles (d eg) for
Ta ble 2. Selected Bon d Dista n ces (Å) a n d Bon d
An gles (d eg) for
[Cp *(P Me3)Ir (1-a d a m a n tyl)(CO)][BAr f] (18)
[Cp *(P Me3)Ir (ter t-bu tyl)(CO)][BP h 4] (15)
(a) Bond Distances
(a) Bond Distances
Ir(1)-P(1)
2.342(5)
2.27(1)
1.78(1)
1.11(2)
1.977(1)
Ir(1)-;C(1)
Ir(1)-C(2)
Ir(1)-C(3)
Ir(1)-C(4)
Ir(1)-C(5)
2.349(7)
2.337(6)
2.287(6)
2.268(7)
2.308(7)
Ir(2)-P(2)
2.317(2)
2.215(6)
1.837(9)
1.155(8)
1.9466(6)
Ir(2)-C(21)
Ir(2)-C(22)
Ir(2)-C(23)
Ir(2)-C(24)
Ir(2)-C(25)
2.270(7)
2.328(7)
2.256(7)
2.271(7)
2.308(7)
Ir(1)-C(15)
Ir(1)-C(11)
O(1)-C(11)
Ir(2)-C(35)
Ir(2)-C(31)
O(2)-C(31)
Ir(1)-Cp* centroid
Ir(2)-Cp* centroid
(b) Bond Angles
C(15)-Ir(1)-Cp* centroid 124.4(3)
85.4(6) C(11)-Ir(1)-Cp* centroid 127.6(5)
92.1(3) P(1)-Ir(1)-Cp* centroid 128.1(1)
86.3(6)
(b) Bond Angles
Ir(1)-C(11)-O(1) 173(1)
Ir(2)-C(31)-O(2)
P(2)-Ir(2)-C(31)
P(2)-Ir(2)-C(35)
C(31)-Ir(2)-C(35)
176.5(7) C(35)-Ir(2)-Cp* centroid 126.2(2)
P(1)-Ir(1)-C(11)
P(1)-Ir(1)-C(15)
C(11)-Ir(1)-C(15)
90.9(2) C(31)-Ir(2)-Cp* centroid 125.6(3)
92.3(2) P(2)-Ir(2)-Cp* centroid
125.37(9)
84.6(3)
complex 15. Pale yellow bladelike crystals of 18 were
grown from a toluene/CH2Cl2 solution at -30 °C over 1
week. Complex 18 crystallized in the space group C2/c
(No. 15) with eight cation/anion pairs and a toluene of
solvation in the unit cell. The data collection and
refinement parameters are provided in the Experimen-
tal Section in Table 4. The bonding and molecular
geometry of the major component of the cationic portion
of 18 are illustrated in Figure 3. The structure clearly
shows that the molecule has a standard three-legged
piano-stool geometry, with the 1-adamantyl ligand
σ-bonded to the iridium atom. Unfortunately, the cat-
ionic portion of 18 displayed substantial disorder in the
structure. The details of the structure solution and
refinement are given in the Experimental Section. A
listing of selected bond distances and angles is located
in Table 3; these data should be interpreted with care
due to the disorder in the structure.
Sch em e 4
Rea ctivity of Selected Ca tion ic Hyd r oca r byl
Ca r bon yl Com p lexes: Deca r bon yla tion a n d At-
tem p ted Ca r bon yla tion Rea ction s. The products of
the reactions discussed above may be further elaborated.
Photolysis of a sample of phenyl carbonyl complex 6 in
a sealed Pyrex NMR tube resulted in decarbonylation.33
In a sealed vessel without an added trap, an apparent
romethane to give [Cp*(PMe3)Ir(1-adamantyl)(CO)]-
[BArf] (18) in 99% yield.
A single-crystal X-ray diffraction study of the 1-ada-
mantyl-substituted complex 18 was undertaken due to
the disorder and twinning in the structure of tert-butyl
(33) We also performed thermal decarbonylation reactions of several
complexes using trimethylamine N-oxide; however, these reactions
were less clean than the photoinitiated reactions.

2134 Organometallics, Vol. 19, No. 11, 2000
Alaimo et al.
Sch em e 5
photostationary state was established between 6 and
Cp*(PMe3)Ir(Ph)(OTf) (19) in CD2Cl2 solution (eq 3).
hν
[Cp*(PMe )Ir(Ph)(CO)][OTf]
y∆
z
3
6
Cp*(PMe )Ir(Ph)(OTf)
+ CO (3)
3
19
Upon standing overnight in ambient room light, the
Cp*(PMe3)Ir(Ph)(OTf) (19) generated by the photolysis
reacted with the liberated CO to re-form starting
material 6. When a similar photolysis of methyl deriva-
tive 2 was performed in the presence of trimethylphos-
phine (10-fold excess), added to act as a trap for 1,
[Cp*(PMe3)2Ir(Me)][OTf] (20) was formed in 42% yield
(vs trimethoxybenzene internal standard) (eq 4). Com-
hν, PMe3
[Cp*(PMe3)Ir(Me)(CO)][OTf]
8
not afford 24. Since it was unclear whether these
reactions were unsuccessful due to kinetic or thermo-
dynamic concerns, two additional experiments were
performed. In the first experiment, variable-tempera-
ture NMR spectroscopy on the high-pressure (10 atm)
sample was used to determine whether any acyl carbo-
nyl complex 24 was formed at high temperature, which
upon cooling to room temperature rapidly returned to
a mixture of 2 and carbon monoxide. NMR spectra (1H
and 31P{1H}) of this reaction obtained between 20 and
100 °C showed no additional resonances, providing no
evidence for this hypothesis. In our second experiment,
we attempted to synthesize Cp*(PMe3)Ir(COMe)(Cl) by
addition of [PPN][Cl] to a CD2Cl2 solution of 2. This also
failed to cleanly produce a new acyl-iridium complex.
Ca r b on yl R ed u ct ion R ea ct ion s.34-36 Addition of
excess NaBH4 or LiAlH4 to methyl carbonyl complex 2
resulted in the complete reduction of the CO ligand to
a methyl group, leading to complex 26 (eq 6). Similarly,
CD2Cl2
2
[Cp*(PMe ) Ir(Me)][OTf]
+ CO (4)
3 2
20
plex 20 was synthesized independently by addition of
PMe3 to 1; details are given in the Experimental Section.
Photolysis of cyclopropyl complex 5 under the reaction
conditions described above gave a somewhat different
result. In the absence of an added trap, the reaction
afforded [Cp*(PMe3)Ir(η3-allyl)][OTf] (21) (eq 5). This
hν
[Cp*(PMe3)Ir(c-Pr)(CO)][OTf]
8
CD2Cl2
5
3
+ CO (5)
[Cp*(PMe3)Ir(η -allyl)][OTf]
21
complex was presumably formed via the cyclopropyl
complex Cp*(PMe3)Ir(c-Pr)(OTf) by â-alkyl elimination
(see Discussion). When the photolysis was instead
performed in the presence of a trap such as PMe3 (in
10-fold excess), or in neat CH3CN, formation of an
intractable mixture of complexes resulted. Thus, inter-
molecular trapping of the decarbonylated intermediate
“Cp*(PMe3)Ir(c-Pr)” to form [Cp*(PMe3)Ir(c-Pr)(L)][OTf]
(L ) PMe3, CH3CN) (22) could not be cleanly effected.
The â-alkyl elimination (ring-opening) reaction ob-
served in the photolysis of cyclopropyl complex 5
prompted us to investigate whether clean â-hydride
elimination reactions could be induced in any of our
tertiary alkyl complexes. Photolysis of tert-butyl-sub-
stituted complex 14 in CD2Cl2 did not yield the isobu-
tylene hydride complex [Cp*(PMe3)Ir(H)(CH2dCMe2)]-
[OTf] (23) cleanly. Although a single metal hydride
resonance and new olefinic resonances were observed
in the 1H NMR spectrum, five different sets of reso-
nances for the Cp* and PMe3 ligands were also present.
Similarly, photolysis of 1-adamantyl salt 17 afforded
only intractable mixtures of products.
NaBH4 or LiAlH4
[Cp*(PMe3)Ir(Me)(CO)][OTf]
8
THF
2
Cp*(PMe3)IrMe2
(6)
26
Cp*(PMe3)Ir(p-tolyl)(Me) (27) was synthesized by ad-
dition of excess NaBH4 to 8 (Scheme 5). Spectroscopic
data for Cp*(PMe3)Ir(Me)2 (26)37 and Cp*(PMe3)Ir(p-
tolyl)(Me) (27)38 are in excellent agreement with the
values reported in the literature. Interestingly, we have
been able to isolate one of the compounds that is
presumably an intermediate on the CO-to-methyl re-
duction pathway for complex 8, formyl (IrCHO) complex
28 (Scheme 5).39-49 Careful addition of 1 equiv of
LiBEt3H to 8 gave 28 in 84% yield. The 1H NMR
(34) Reduction of transition-metal carbonyl ligands to formyl, hy-
droxymethyl, and methyl ligands has been observed before. For leading
references, see refs 35-36.
(35) Berke, H.; Weiler, G. Angew. Chem., Int. Ed. Engl. 1982, 21,
150-151.
Further derivatization of the hydrocarbyl carbonyl
complexes 2-10 could conceivably be effected via their
carbonylation. However, thermolysis (105 °C) of methyl
and phenyl carbonyl complexes 2 and 6 under 1 atm of
carbon monoxide did not give the corresponding acyl
carbonyl complexes [Cp*(PMe3)Ir(COR)(CO)][OTf] (R )
Me, 24; R ) Ph, 25). Furthermore, subjection of 2 to
more forcing conditions (10 atm CO, 135 °C) also did
(36) Thorn, D. L. J . Am. Chem. Soc. 1980, 102, 7109-7110.
(37) Buchanan, J . M.; Stryker, J . M.; Bergman, R. G. J . Am. Chem.
Soc. 1986, 108, 1537-1550.
(38) Diversi, P.; Iacoponi, S.; Ingrosso, G.; Laschi, F.; Lucherini, A.;
Zanello, P. J . Chem. Soc., Dalton Trans. 1993, 351-352.
(39) The scarcity of reported formyl and hydroxymethyl complexes
synthesized by reduction of a CO ligand is due to the ease by which
these complexes undergo further reduction. For recent examples of
transition-metal formyl complexes see refs 40-49.
(40) Gladysz, J . A. Adv. Organomet. Chem. 1982, 20, 1-38.

Alkylation of Iridium
Organometallics, Vol. 19, No. 11, 2000 2135
Sch em e 6
spectrum of 28 contains a resonance at δ 13.97 (IrCHO),
and the 13C{1H} NMR spectrum contains a broad formyl
carbon resonance at δ 231.6 that was positive in a DEPT
90 experiment. These chemical shift values are not
unusual for transition-metal formyl complexes.40 Al-
though addition of 2 equiv of LiBEt3H to 8 should give
the lithiated hydroxymethyl complex (IrCH2OLi) 29
(Scheme 5), we were unsuccessful in isolating this
complex.
hydride, we conclude that no C-H activation has
occurred. Purification of these complexes by recrystal-
lization from CH2Cl2 or chromatography (air-free) on
dried silica, alumina I, or alumina III was unsuccessful.
Addition of N,N-dimethylformamide (Me2NCHO) (1.5
equiv) to 1 gave two major and more than seven minor
products that could also not be purified. Addition of
alkyl-substituted formates (ROCHO; R ) Me, Et, t-Bu)
(1.5 equiv) gave mixtures of three to five reaction
products that also could not be purified by repeated
crystallization attempts.
Rea ction s of 1 w ith Oth er Or ga n ic Molecu les
Th a t Con ta in th e -CHE (E ) O, NR) Moiety. The
addition of aldimines, formates, or formamides to 1
yielded no isolable examples of the alkyl isocyanide,
alkoxy carbonyl, or amido carbonyl complexes (Scheme
6) that might be anticipated by analogy to the reaction
of 1 with aldehydes. Instead, apparent adduct formation
occurred with aldimines,50-52 and intractable product
mixtures resulted from reaction of 1 with formates or
formamides. Addition of 1.5 equiv of aldimines (RNd
CRH, R ) Ph, p-tolyl) to 1 resulted in rapid formation
of one major product (30; Scheme 6) and several minor
products (determined by 1H and 31P{1H} NMR spec-
Discu ssion
Activa tion of Ald eh yd e C-H Bon d s. The activa-
tion of the aldehydic C-H bond has been observed in
several other laboratories, occurring with iron(0),53
ruthenium(0),54,55 ruthenium(II),56 osmium(0),57-59 rho-
dium(I),60-66 rhodium(III),67 iridium(I),66,68-73 iridium-
(III),67 and platinum(0).74 In some cases, the C-H
activation step is followed by decarbonylation of the
metal-acyl intermediate;55,56,67-70,74 in others an acyl
hydride complex is the stable product of the reac-
tion.57,58,66,74 The only published example to date of
1
troscopy). The H NMR spectrum of the major compo-
nent of the reaction mixture contained new resonances
for the Cp* ligand (R ) Ph, 1.71 ppm; R ) p-tolyl, 1.69
ppm), the PMe3 ligand (R ) Ph, 1.27 ppm; R ) p-tolyl,
1.29 ppm), and the Ir-Me moiety (R ) Ph, 0.58 ppm; R
) p-tolyl, 0.50 ppm) as well as new aryl resonances. A
new aldimine (RNdCRH) proton was also visible at 8.46
ppm (R ) Ph) and 8.17 ppm (R ) p-tolyl). The major
resonance in the 31P{1H} NMR spectrum appeared at
-34.2 ppm (R ) Ph) and -32.0 ppm (R ) p-tolyl). From
these data and the absence of any resonances indicative
of the formation of either methane or a new iridium
(53) Tolman, C. A.; Ittel, S. D.; English, A. D.; J esson, J . P. J . Am.
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Richardson, J . F. Organometallics 1998, 17, 5178-5183.
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(50) The formation of iridium adducts of aldimines is not surprising,
considering the higher basicity of the nitrogen of imines51 and the
thorough work of Gladysz and co-workers.52
(51) Faller, J . W.; Ma, Y.; Smart, C. J .; DiVerdi, M. J . J . Organomet.
Chem. 1991, 420, 237-252.
(71) Landvatter, E. F.; Rauchfuss, T. R. Organometallics 1982, 1,
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(52) Stark, G. A.; Gladysz, J . A. Inorg. Chim. Acta 1998, 269, 167-
180 and references therein.

2136 Organometallics, Vol. 19, No. 11, 2000
Alaimo et al.
Sch em e 7
aldehydic C-H bond activation by an iridium(III)
complex was reported in 1985.67 In that study, Maitlis
and co-workers found that the neutral complexes Cp*M-
(Me)2(DMSO) (M ) Rh, Ir) reacted with aldehydes in
cyclohexane solution at 80 °C over several (4-24) hours.
Much of the activity in this area has been focused on
demonstrating the intermediacy of acyl hydride com-
plexes in processes such as the metal-catalyzed carbon-
ylation of C-H bonds,75,76 hydroformylation of ole-
fins,76-79 and decarbonylation reactions of alde-
hydes.76,80-82 The majority of the research on aldehyde
decarbonylation has utilized Rh(I) complexes as cata-
lysts,83-91 since these have been found to be most
efficient; however, some systems utilizing Pd/C,92 ru-
thenium(II),93 cobalt(I),94 cobalt(II),95,96 iridium(I),69,70
and scandium(III)97 complexes have also been success-
ful.
selectivity displayed in reactions between 1 and organic
substrates which present a variety of C-H bond types
(i.e., primary, secondary, aromatic, benzylic, etc.).18,20
One important goal of the work presented here was to
further examine the degree of selectivity of the highly
reactive reagent 1. Despite the fact that the activation
of aldehydes by 1 is usually complete within 1 min at
room temperature, and at rapid rates at temperatures
as low as -60 °C, the reactions of 1 with aldehydes
proceed with a very high degree of selectivity. In most
1
cases only a single product is observed by H and 31P-
{1H} NMR spectroscopy. High yields (quantitative by
NMR spectroscopy, 63-87% following recrystallization
or precipitation) of the iridium(III) hydrocarbyl carbonyl
cations 2-10, 13, 14, and 17 are obtained, and there is
no evidence for activation of any C-H bond other than
the aldehydic one.
P r op osed Mech a n ism of C-H Activa tion a n d
Su bsequ en t R ea r r a n gem en t s. On the basis of our
previous studies of complex 1 and its related BArf salt
([Cp*(PMe3)IrMe(CH2Cl2)][BArf]) we postulate that these
C-H activation reactions proceed through coordina-
tively unsaturated cationic species 31 (Scheme 7).14-16
Although we have observed benzaldehyde adduct 11 at
-80 °C by NMR spectroscopy, it is unclear whether 11
is an intermediate on the reaction pathway or simply a
kinetic “dead end” formed reversibly from 31. One
mechanistic possibility is that the C-H activation step
occurs via an iridium(V) intermediate such as 32. This
proposed Ir(V) intermediate could form either from
aldehyde adduct 11 or by an intermolecular pathway
(from 31 and aldehyde). While kinetics experiments
designed to distinguish between these pathways were
attempted, the reactions were too rapid to obtain high-
Selectivity of C-H Activa tion . Earlier researchers
in our group primarily investigated the activation of
organic substrates that contained only one type of C-H
bond (e.g., methane, benzene, cyclopropane, ace-
tone).14,15,17 Since then, our studies have focused on the
(75) Cornils, B.; Herrmann, W. A. Applied Homogeneous Catalysis
with Organometallic Compounds: A Comprehensive Handbook in Two
Volumes; VCH: New York, 1996; Vols. 1-2, pp 194-196, 1085.
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(79) See ref 21, pp 621-632.
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Alkylation of Iridium
Organometallics, Vol. 19, No. 11, 2000 2137
Ch a r t 1. Com p lete List of P r eviou sly Rep or ted
Gr ou p 9 Ter tia r y Alk yl Com p lexes
quality data using conventional kinetics techniques.
Reductive elimination of methane from acyl hydride 32
would form the coordinatively unsaturated acyl complex
33, and migratory deinsertion of CO from 33 would give
the observed product. Alternatively, the C-H activation
could occur by a concerted σ-bond metathesis reaction;
however, we disfavor this mechanistic possibility based
on prior research.98-100
Syn th esis of Un u su a l Alk yl Com p lexes of Ir i-
d iu m . One of the most notable features of this chem-
istry is the fact that even when the alkyl group on the
aldehyde is tertiary, the reaction still proceeds to give
an Ir(tertiary alkyl) product. The migratory CO dein-
sertion reaction proposed above occurs readily, in spite
of the fact that it brings sterically demanding groups
(mesityl, tert-butyl, 1-adamantyl) in close proximity to
the metal center. Acyl species 33 could conceivably
achieve coordinative and electronic saturation by coor-
dination of the acyl oxygen atom to the iridium to form
a stable η2-acyl complex. Instead, even with very
hindered groups, the deinsertion reaction occurs. We
believe this process is likely driven in large part by the
high M-CO bond energy.
The first syntheses of transition-metal complexes
containing tertiary alkyl ligands were reported in
1972.101-103 Since then, very few tertiary alkyl com-
plexes of any of the transition metals have been
described.104-116 Such complexes have been difficult to
isolate, due to their propensity to decompose to stable
transition-metal hydrides via further reactions such as
â-elimination.117 Most of the stable transition-metal
tertiary alkyl complexes are either coordinatively satu-
rated, and thus have a very high barrier to â-elimina-
tion, or are stable because upon undergoing â-elimina-
tion they would form thermodynamically unstable
bridgehead alkenes. In group 9, we are aware of a few
isolated tertiary alkyl complexes of cobalt118-125 and
rhodium126 (Chart 1) but none of iridium.127,128 To the
best of our knowledge, tert-butyl and 1-adamantyl salts
14, 15 and 17, 18 are the first such reported complexes.
This methodology has also allowed for the synthesis
of cyclopropyl derivative 5. Though few cyclopropyl-
substituted transition-metal complexes have been re-
ported, most of those that are known have been pre-
pared by one of two general methods: Grignard (or
Grignard-like) substitutions of metal halides129-133 and
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(127) Our group prepared the first and only known tertiary alkyl
iridium complex, a cubyl iridium species, but did not isolate it:
Sponsler, M. B.; Weiller, B. H.; Stoutland, P. O.; Bergman, R. G. J .
Am. Chem. Soc. 1989, 111, 6841-6843.
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2138 Organometallics, Vol. 19, No. 11, 2000
Alaimo et al.
Sch em e 8
C-H activation of cyclopropane by the transiently
generated Cp′(PMe3)M (Cp′ ) Cp, Cp*; M ) Rh, Ir)
fragment.128,134-139
Decarbonylation of transition-metal carbonyl com-
plexes has been used to perform ligand substitution140
and rearrangement reactions.141 In this study, we have
utilized this reaction to gain further evidence about the
putative intermediate in the reaction between 1 and
cyclopropane. Treatment of 1 with cyclopropane results
in the formation of methane (1 equiv) and π-allyl
complex [Cp*(PMe3)Ir(η3-allyl)][OTf] (21) (Scheme 8).15
We assume that C-H activation affords a coordinatively
unsaturated cyclopropyl complex (34), although we have
never observed such an intermediate directly. We
therefore postulate that this intermediate undergoes
rapid ring opening by a kinetically facile â-alkyl elimi-
nation reaction to produce the observed product.142 It
occurred to us that photochemically induced decarbon-
ylation of the cyclopropyl carbonyl complex (5) would
provide an alternate route to 34. The observation of
π-allyl complex [Cp*(PMe3)Ir(η3-allyl)][OTf] (21) as the
reaction product in the decarbonylation of 5 lends
further support to our proposal involving coordinatively
unsaturated cyclopropyl intermediate 34.143-145
The success of the â-alkyl elimination reaction of 5
prompted us to attempt to induce â-hydride elimination
from tert-butyl complex 14 and 1-adamantyl complex
17. Decarbonylation followed by â-hydride elimination
from 14 or 17 would result in the formation of isobu-
tylene hydride 23 or adamantene hydride complex 35,
respectively. Of particular interest to us was the decar-
bonylation of 17, as it presented a possible method for
forming metal-stabilized highly strained anti-Bredt
bridgehead alkenes.146-152 Unfortunately, we were not
able to cleanly promote â-hydride elimination from
We feel that our ability to access these unusual
organometallic compounds is intimately linked to the
tandem nature of the C-H activation/decarbonylation
steps and the resulting absence of a coordinatively
unsaturated alkyl complex on the reaction pathway. In
the aldehyde C-H activation reaction, we propose that
the coordinatively unsaturated acyl complexes (33)
proposed as intermediates undergo rearrangement by
a carbonyl migratory deinsertion reaction to directly
form 18-electron hydrocarbyl carbonyl complexes 2-10,
13, 14, and 17. This reaction sequence allows for the
direct alkylation of iridium by the overall transfer of
the R group from the aldehyde (RCHO) to the metal
without any subsequent rearrangement of the alkyl
group. Thus, whereas 1 does not react cleanly with
tertiary C-H bonds to give stable tert-butyl-substituted
iridium compounds, reaction of 1 with 2,2-dimethylpro-
panal proceeds rapidly and cleanly to afford tert-butyl
complex 14 with no detectable side products. Likewise,
reaction of 1 with cyclopropane produces a π-allyl
complex, while cyclopropyl-substituted complex 5 can
be easily synthesized free of ring-opened products using
cyclopropanecarboxaldehyde. In essence, the CO dein-
sertion reaction serves to protect the alkyl group by
filling the coordination site on the metal center.
Ela bor a tion of th e P r od u cts of th e Ta n d em C-H
Activa tion /Deca r bon yla tion Rea ction s. To demon-
strate additional utility of the tandem reaction described
above for the synthesis of novel iridium alkyl complexes,
we sought to elaborate complexes 2-10, 13, 14, and 17.
We explored decarbonylation, carbonylation, and car-
bonyl reduction reactions of these molecules.
(140) Elschenbroich, A. S. Organometallics, A Concise Introduction,
2nd ed.; VCH: New York, 1992; p 244.
(141) See ref 21, p 362.
(142) For a recent leading reference to â-alkyl elimination, see:
McNeill, K.; Andersen, R. A.; Bergman, R. G. J . Am. Chem. Soc. 1997,
119, 11244-11254.
(131) Reetz, M. T.; Westermann, J .; Steinbach, R.; Wenderoth, B.;
Roland, P. Chem. Ber. 1985, 118, 1421-1440.
(132) Yin, J . G.; J ones, W. M. Organometallics 1993, 12, 2013-2014.
(133) Reamey, R. H.; Whitesides, G. M. J . Am. Chem. Soc. 1984,
106, 81-85.
(143) As a reviewer has pointed out, the conversion of a transition-
metal σ-cyclopropyl complex to an η3-allyl complex has been observed
in other laboratories. In 1978, Phillips and Puddephatt showed that
trans-[Pt(c-Pr)Cl(PMe2Ph)2] reacts with Ag(NO3) in the presence of
KPF6 to produce [Pt(η3-C3H5)(PMe2Ph)2][PF6]. They demonstrated that
this reaction occurs by cleavage of the â-C-C bond via a deuterium
labeling study.144 A similar reaction was reported by Lehmkuhl and
co-workers.145
(134) Wenzel, T. T.; Bergman, R. G. J . Am. Chem. Soc. 1986, 108,
4856-4867.
(135) Periana, R. A.; Bergman, R. G. J . Am. Chem. Soc. 1986, 108,
7332-7346.
(136) McGhee, W. D.; Bergman, R. G. J . Am. Chem. Soc. 1988, 110,
4246-4262.
(144) Philips, R. L.; Puddephatt, R. J . J . Chem. Soc., Dalton Trans.
1978, 1732-1735.
(145) Lehmkuhl, H.; Naydowski, C.; Danowski, F.; Bellenbaum, M.;
Benn, R.; Rufinska, A.; Schroth, G.; Mynott, R.; von Stanislaw
Pasynkiewicz, M. Chem. Ber. 1984, 117, 3231-3254.
(146) For examples of strained organic molecules that are stabilized
by coordination to transition-metal fragments, see refs 147-152.
(137) Fendrick, C. M.; Marks, T. J . J . Am. Chem. Soc. 1986, 108,
425-437.
(138) Bergman, R. G.; Seidler, P. F.; Wenzel, T. T. J . Am. Chem.
Soc. 1985, 107, 4358-4359.
(139) Periana, R. A.; Bergman, R. G. J . Am. Chem. Soc. 1984, 106,
7272-7273.

Alkylation of Iridium
Organometallics, Vol. 19, No. 11, 2000 2139
Berkeley Microanalytical Facility, on a Perkin-Elmer 2400
Series II CHNO/S analyzer.
either 14 or 17 by photoinduced decarbonylation. This
lack of clean reactivity provides further support for the
tandem nature of the reactions between 1 and alde-
hydes.
Sealed NMR tubes were prepared by attaching the NMR
tube directly to a Kontes high-vacuum stopcock via a Cajon
Ultra-Torr reducing union and then flame-sealing on a vacuum
line. Reactions with gases and low-boiling liquids involved
condensation of a calculated pressure of gas from a bulb of
known volume into the reaction vessel at -196 °C. Known
volume bulb vacuum transfers were accomplished with a
digital MKS Baratron gauge attached to a high-vacuum line.
In our proposed mechanism, acyl intermediate 33
undergoes a carbonyl migratory deinsertion reaction
(Scheme 7). Many groups have studied the mechanism
of this reaction type with a variety of complexes.153-155
The carbonylation of methyl carbonyl complex 2 was
attempted to test whether this step is reversible.
However, even under 10 atm of CO pressure, 2 does not
react to form acetyl carbonyl complex 24. At the present
time, it is unclear whether (a) the migratory deinsertion
step is irreversible, (b) trapping of the acyl intermediate
with exogenous CO is kinetically incompetent, or (c)
complex 24 lies thermodynamically uphill relative to 2
and CO.
Ma ter ia ls. Unless otherwise noted, reagents were pur-
chased from commercial suppliers and used without further
purification. Potassium bromide (Aldrich), Celite (Aldrich), and
silica gel (Merck 60, 230-400) were dried in vacuo at 250 °C
for 48 h. Toluene (Fisher) was either distilled from sodium
metal under N2 or passed through a column of activated
alumina (type A2, size 12 × 32, Purifry Co.) under nitrogen
pressure and sparged with N2 prior to use.156 Pentane, hex-
anes, and benzene (Fisher) were either distilled from purple
sodium/benzophenone ketyl under N2 or passed through a
column of activated alumina under nitrogen pressure and
sparged with N2 prior to use.156 Diethyl ether and tetrahydro-
furan (Fisher) were distilled from purple sodium/benzophenone
ketyl under N2 prior to use. Dichloromethane (Fisher) was
either distilled from CaH2 (Aldrich) under N2 or passed
through a column of activated alumina under nitrogen pres-
sure and sparged with N2 prior to use.156 Deuterated solvents
(Cambridge Isotope Laboratories) were purified by vacuum
transfer from the appropriate drying agent (Na/Ph2CO or
CaH2) prior to use. Trimethylphosphine (Aldrich) was vacuum-
transferred from sodium metal prior to use. Aldehydes were
purified as follows: all were washed with NaHCO3 to remove
traces of the corresponding carboxylic acid;157 acetaldehyde,
acetaldehyde-1-d, propionaldehyde, butyraldehyde, cyclopro-
panecarboxaldehyde, 2-ethylbutanal, benzaldehyde, tolualde-
hyde, mesitaldehyde, R-methylcinnamaldehyde, pivaldehyde
(Aldrich, distilled from 4 Å molecular sieves); acrolein (Aldrich,
vacuum transferred from CaSO4). Sodium tetraphenylborate
(Aldrich) was dried over 4 Å molecular sieves in CHCl3 and
then recrystallized. The following complexes were prepared
according to literature proceedures: Cp*(PMe3)Ir(Me)(OTf)
(1),15 NaBArf.158 Spectroscopic data for Cp*(PMe3)Ir(Ph)(OTf)
(19),159 [Cp*(PMe3)Ir(η3-allyl)][OTf] (21),15 Cp*(PMe3)IrMe2
(26),37 and Cp*(PMe3)Ir(p-tolyl)(Me) (27)38 were in accord with
literature values.
Gen er a l P r oced u r e for th e Syn th esis of [Cp *(P Me3)-
(Ir (R)(CO)][OTf] (2-10, 14, 17). Synthesis was performed
by dissolving iridium triflate 1 in dichloromethane (5 mL) in
a 20 mL scintillation vial. The aldehyde was dissolved in
dichloromethane (1 mL), and this solution was added to the
iridium triflate solution over 1 min. This resulted in vigorous
evolution of methane. The mixture was then stirred at room
temperature overnight. The volatile materials were then
removed in vacuo, and the remaining solids were washed with
diethyl ether (to remove excess aldehyde) and purified as
described in each specific case below.
[Cp *(P Me3)Ir (Me)(CO)][OTf] (2). Synthesis was per-
formed by employing the general procedure described above
using 42.5 mg (0.075 mmol) of 1 and 6.6 mg (0.150 mmol) of
ethanal. Complex 2 was isolated (37.6 mg, 0.063 mmol) as a
white powder (84% yield) by precipitation from CH2Cl2 solution
by addition of Et2O. Mp: >250 °C. 1H NMR (CD2Cl2, 400
MHz): δ 1.97 (d, 4J P-H ) 2.1 Hz, 15H, C5(CH3)5), 1.69 (d, 2J P-H
Con clu sion
The tandem C-H activation/carbonyl migratory dein-
sertion reaction described in this work has provided
access to complexes, including tertiary alkyl and cyclo-
propyl substituted complexes, that are not easily syn-
thesized by other routes. We feel that the success of this
synthetic method is a direct consequence of the tandem
nature of the reaction mechanism. The photochemically
initiated decarbonylation of cyclopropyl carbonyl com-
plex 5 has provided supporting evidence for the occur-
rence of â-alkyl elimination in the proposed intermedi-
ate 34 formed by cyclopropane C-H activation. Further
efforts in our laboratory toward utilizing Cp*(PMe3)Ir-
(Me)OTf (1) for the synthesis of other unusual organo-
metallic complexes are in progress.
Exp er im en ta l Section
Gen er a l P r oced u r es. Unless otherwise noted, reactions
and manipulations were performed at 23 °C in an inert-
atmosphere (N2) glovebox, or using standard Schlenk and high-
vacuum-line techniques. Glassware was dried overnight at 150
°C before use. All NMR spectra were obtained at room
temperature (except where noted) using Bruker AM 400 MHz
or DRX 500 MHz spectrometers. In cases where assignment
of 13C{1H} NMR resonances from the initial 13C{1H} NMR
spectrum was ambiguous, resonances were assigned using
standard DEPT 45, 90, and/or 135 pulse sequences. Infrared
(IR) spectra were recorded using samples prepared as KBr
pellets or in a standard solution cell with NaCl windows, and
spectral data are reported in wavenumbers (cm-1). Mass
spectrometric (MS) analyses were obtained at the University
of California, Berkeley Mass Spectrometry Facility, on VT
ProSpec, ZAB2-EQ, and 70-FE mass spectrometers. Unless
otherwise noted, all FAB MS data were acquired from samples
in a methylene chloride/3-nitrobenzyl alcohol matrix. Elemen-
tal analyses were performed at the University of California,
(147) Lee, G. A.; Lin, Y. H.; Huang, A. N.; Li, Y. C.; J ann, Y. C.;
Chen, C. S. J . Am. Chem. Soc. 1999, 121, 5328-5329.
(148) Wijsman, G. W.; Dewolf, W. H.; Bickelhaupt, F.; Kooijman,
H.; Spek, A. L. J . Am. Chem. Soc. 1992, 114, 9191-9192.
(149) Warner, P. M. Chem. Rev. 1989, 89, 1067-1093.
(150) Borden, W. T. Chem. Rev. 1989, 89, 1095-1109.
(151) Bly, R. S.; Hossain, M. M.; Lebioda, L. J . Am. Chem. Soc. 1985,
107, 5549-5550.
(156) Alaimo, P. J .; Peters, D. W.; Arnold, J .; Bergman, R. G. J .
Chem. Educ., in press.
(152) Godleski, S. A.; Gundlach, K. B.; Valpey, R. S. Organometallics
1985, 4, 296-302.
(157) Perrin, D. D.; Armarego, W. L. F. Purification of Laboratory
Chemicals, 3rd ed.; Pergamon Press: New York, 1988; p 66.
(158) Brookhart, M.; Grant, B.; Volpe, A. F., J r. Organometallics
1992, 11, 3920-3922.
(159) Woerpel, K. A.; Bergman, R. G. J . Am. Chem. Soc. 1993, 115,
7888-7889.
(153) See ref 21, pp 356-376.
(154) Cavell, K. J . Coord. Chem. Rev. 1996, 155, 209-243.
(155) Blomberg, M. R. A.; Karlsson, C. A. M.; Siegbahn, P. E. M. J .
Phys. Chem. 1993, 97, 9341-9350.

2140 Organometallics, Vol. 19, No. 11, 2000
Alaimo et al.
3
1
) 11.1 Hz, 9H, P(CH3)3), 0.51 (d, J P-H ) 6.0 Hz, 3H, IrCH3).
i-C6H5), 86.4 (s, C5(CH3)5), 17.4 (d, J P-C ) 42.0 Hz, P(CH3)3),
11.1 (s, C5(CH3)5). 19F NMR (CD2Cl2): δ -77.0. 31P{1H} NMR
(CD2Cl2): δ -33.0. IR: (CH2Cl2) 2927 (w), 2035 (vs), 1276 (vs),
1164 (s), 1039 (s), 643 (m). FAB LRMS: m/z 509 ([Cp*(PMe3)-
Ir(Ph)(CO)]+). Anal. Calcd for C21H29F3IrO4PS: C, 38.35; H,
4.44. Found: C, 38.19; H, 4.46.
13C{1H} NMR (CD2Cl2, 101 MHz): δ 167.6 (d, J P-C ) 11.8
2
Hz, CO), 102.0 (s, C5(CH3)5), 14.3 (d, 1J P-C ) 42.3 Hz, P(CH3)3),
8.8 (s, C5(CH3)5), -25.6 (d, J P-C ) 7.0 Hz, IrCH3). 19F NMR
2
(CD2Cl2): δ -77.7 (s). 31P{1H} NMR (CD2Cl2): δ -34.9 (s). IR
(CD2Cl2): 2035 (s), 1271 (vs). Anal. Calcd for C16H27F3IrO4PS:
C, 32.26; H, 4.57. Found: C, 32.38; H, 4.60.
[Cp *(P Me3)Ir (1-et h ylp r op yl)(CO)][OTf] (7). Synthesis
was performed employing the general procedure described
above using 117 mg (0.206 mmol) of 1 and 22.7 mg (0.227
mmol) of 2-ethylbutanal. Compound 7 was isolated (106 mg,
0.162 mmol) as a pale yellow powder (79% yield) by precipita-
tion from CH2Cl2 solution by addition of Et2O. Mp: 222-225
[Cp *(P Me3)Ir (Et)(CO)][OTf] (3). Synthesis was performed
by employing the general procedure described above using 111
mg (0.196 mmol) of 1 and 14.8 mg (0.254 mmol) of propanal.
After removal of the volatile materials, 3 was dissolved in 1
mL of CH2Cl2 and then precipitated by addition of 3 mL of
Et2O. Compound 3 was isolated (77.0 mg, 0.126 mmol) as a
white powder (64% yield). Mp: 249-251 °C. 1H NMR (CD2-
Cl2, 400 MHz): δ 2.02 (d, 4J P-H ) 2.4 Hz, 15H, C5(CH3)5), 1.75
°C. 1H NMR (CD2Cl2, 400 MHz): δ 2.02 (d, J P-H ) 2.1 Hz,
4
2
15H, C5(CH3)5), 1.79 (m, 2H, CH2), 1.78 (d, J P-H ) 10.8 Hz,
3
9H, P(CH3)3), 1.47 (m, 2H, CH2), 0.95 (t, J H-H ) 7.2 Hz, 3H,
2
3
(d, J P-H ) 11.2 Hz, 9H, P(CH3)3), 1.58-1.80 (m, 1H, diaste-
CH3), 0.93 (t, J H-H ) 7.2 Hz, 3H, CH3). 13C{1H} NMR (CD2-
3
3
reotopic CH2CH3), 1.48 (dd, J H-H ) 7.2 Hz, J H-H ) 7.2 Hz,
Cl2, 101 MHz): δ 169.0 (d, 2J P-C ) 12.0 Hz, CO), 123.0 (q, 1J C-F
) 319 Hz, CF3), 105.0 (s, C5(CH3)5), 35.8 (s, CH2), 24.0 (s, CH),
3H, CH2CH3), 1.27-1.36 (m, 1H, diastereotopic CH2CH3). 13C-
{1H} NMR (CD2Cl2, 101 MHz): δ 168.3 (d, J P-C ) 11.8 Hz,
18.3 (s, CH3), 17.8 (d, J P-C ) 37.1 Hz, P(CH3)3), 11.3 (s, C5-
2
1
CO), 102.9 (s, C5(CH3)5), 21.7 (s, CH2CH3), 15.1 (d, 1J P-C ) 40.0
(CH3)5). 19F NMR (CD2Cl2): δ -76.7 (s). 31P{1H} NMR (CD2-
Cl2): δ -32.94 (s). IR (CD2Cl2): 2011 (s), 1269 (s), 1145 (m),
1029 (m), 950 (m), 636 (m). Anal. Calcd for C20H35F3IrO4PS:
C, 36.86; H, 5.41. Found: C, 36.56; H, 5.30.
2
Hz, P(CH3)3), 9.3 (s, C5(CH3)5), -6.9 (d, J P-C ) 10.0 Hz, CH2-
CH3). 19F NMR (CD2Cl2): δ -76.9 (s). 31P{1H} NMR (CD2Cl2):
δ -34.15 (s). IR (CD2Cl2): 1997 (s), 1295 (m), 1259 (s), 1222
(s), 1147 (s), 1031 (s), 954 (s), 638 (m). Anal. Calcd for C17H29F3-
IrO4PS: C, 33.49; H, 4.79. Found: C, 33.21; H, 4.56.
[Cp *(P Me3)Ir (p-tolyl)(CO)][OTf] (8). Synthesis was per-
formed by employing the general procedure described above
using 127 mg (0.219 mmol) of 1 and 39.5 mg (0.329 mmol) of
p-tolualdehyde. Compound 8 was isolated (118 mg, 0.176
mmol) as a pale yellow powder (80% yield) by precipitation
from CH2Cl2 solution by addition of Et2O. Mp: 184-185 °C.
[Cp *(P Me3)Ir (n -P r )(CO)][OTf] (4). Synthesis was per-
formed by employing the general procedure described above
using 111 mg (0.196 mmol) of 1 and 18.3 mg (0.254 mmol) of
butanal. Compound 4 was isolated (96 mg, 0.154 mmol) as a
pale yellow powder (79% yield) by precipitation from CH2Cl2
solution by addition of pentane. Mp: 148-150 °C dec. 1H NMR
(CD2Cl2, 400 MHz): δ 2.02 (d, 4J P-H ) 2.0 Hz, 15H, C5(CH3)5),
1.75 (d, 2J P-H ) 10.8 Hz, 9H, P(CH3)3), 1.48 (m, 2H, CH2), 1.13
(m, 2H, CH2), 0.95 (t, 3J H-H ) 6.8 Hz, 3H, CH3). 13C{1H} NMR
1H NMR (CD2Cl2, 400 MHz): δ 7.03 (d, J H-H ) 8.0 Hz, 2H,
3
C6H4CH3), 6.92 (d, 3J H-H ) 7.6 Hz, 2H, C6H4CH3), 2.28 (s, 3H,
4
2
p-CH3), 1.98 (d, J P-H ) 2.0 Hz, 15H, C5(CH3)5), 1.68 (d, J P-H
) 11.2 Hz, 9H, P(CH3)3). 13C{1H} NMR (CD2Cl2, 101 MHz): δ
168 (br s, CO), 139 (s, o-C6H4CH3), 135 (s, p-C6H4CH3), 131 (s,
2
2
(CD2Cl2, 101 MHz): δ 168.2 (d, J P-C ) 11.8 Hz, CO), 102.8
(s, C5(CH3)5), 30.9 (s, CH2CH3), 19.8 (s, CH3), 15.0 (d, J P-C
m-C6H4CH3), 117 (d, J P-C ) 10.7 Hz, i-C6H4CH3), 104 (s, C5-
1
1
)
(CH3)5), 20.6 (s, C6H4CH3), 16.0 (d, J P-C ) 40.2 Hz, P(CH3)3),
2
50.0 Hz, P(CH3)3), 9.3 (s, C5(CH3)5), 2.7 (d, J P-C ) 10.0 Hz,
CH2CH2CH3). 19F NMR (CD2Cl2): δ -76.9 (s). 31P{1H} NMR
(CD2Cl2): δ -33.76 (s). IR (CD2Cl2): 2015 (s), 1459 (m), 1384
(m), 1265 (s), 1147 (s), 1031 (s), 956 (m), 638 (m), 516 (m). Anal.
Calcd for C18H31F3IrO4PS: C, 34.66; H, 5.01. Found: C, 34.26;
H, 4.81.
9.6 (s, C5(CH3)5). 19F NMR (CD2Cl2): δ -77.0 (s). 31P{1H} NMR
(CD2Cl2): δ -33.07 (s). IR (CD2Cl2): 2919 (w), 2017 (s), 1729
(w), 1486 (w), 1270 (s), 1224 (m), 1145 (s), 1031 (m), 945 (m),
636 (m). FAB LRMS: m/z 523 ([Cp*(PMe3)Ir(p-tolyl)(CO)]+).
Anal. Calcd for C22H31F3IrO4PS: C, 39.34; H, 4.65. Found: C,
39.17; H, 4.47.
[Cp *(P Me3)Ir (c-P r )(CO)][OTf] (5). Synthesis was per-
formed by employing the general procedure described above
using 112 mg (0.198 mmol) of 1 and 18.1 mg (0.258 mmol) of
cyclopropanecarboxaldehyde. Compound 5 was isolated (93 mg,
0.150 mmol) as a white powder (76% yield) by precipitation
from CH2Cl2 solution by addition of pentane. Mp: 205 °C dec.
[Cp*(P Me3)Ir (2,4,6-tr im eth ylph en yl)(CO)][OTf] (9). Syn-
thesis was performed by employing the general procedure
described above using 100 mg (0.176 mmol) of 1 and 36.6 mg
(0.247 mmol) of mesitaldehyde. Compound 9 was isolated (89.0
mg, 0.127 mmol) as an ivory-colored powder (72% yield) by
precipitation from CH2Cl2 solution by addition of Et2O. Mp:
163 °C. 1H NMR (CD2Cl2, 400 MHz): δ 6.87 (s, 1H, C6H2-
(CH3)3), 6.83 (s, 1H, C6H2(CH3)3), 2.45 (s, 3H, p-C6H2(CH3)3),
2.22 (s, 3H, o-C6H2(CH3)3), 2.20 (s, 3H, o-C6H2(CH3)3), 1.94 (d,
4
1H NMR (CD2Cl2, 400 MHz): δ 2.04 (d, J P-H ) 2.0 Hz, 15H,
C5(CH3)5), 1.81 (d, 2J P-H ) 11.2 Hz, 9H, P(CH3)3), 1.00 (m, 1H,
c-C3H5), 0.91 (m, 1H, c-C3H5), 0.33 (m, 1H, c-C3H5), 0.21 (m,
1H, -C3H5), 0.13 (m, 1H, c-C3H5). 13C{1H} NMR (CD2Cl2, 101
2
4J P-H ) 2.0 Hz, 15H, C5(CH3)5), 1.76 (d, J P-H ) 10.8 Hz, 9H,
2
2
MHz): δ 168.9 (d, J P-C ) 11.3 Hz, CO), 104.8 (s, C5(CH3)5),
P(CH3)3). 13C{1H} NMR (CD2Cl2, 101 MHz): δ 169.1 (d, J P-C
1
3
17.0 (d, J P-C ) 41.1 Hz, P(CH3)3), 11.3 (d, J P-C ) 1.3 Hz,
) 17.1 Hz, CO), 145.7 (s, o-C6H2(CH3)3), 142.8 (d, J ) 3.0 Hz,
o-C6H2(CH3)3), 134.9 (s, p-C6H2(CH3)3), 129.6 (s, m-C6H2(CH3)3),
129.2 (s, m-C6H2(CH3)3), 123.8 (s, i-C6H2(CH3)3), 104.4 (s, C5-
(CH3)5), 31.1 (s, o-C6H2(CH3)3), 30.7 (d, J ) 5.0 Hz, o-C6H2-
3
CH2), 10.8 (s, C5(CH3)5), 10.2 (d, J P-C ) 3.3 Hz, CH2), -16.4
(d, 2J P-C ) 10.4 Hz, CH). 19F NMR (CD2Cl2): δ -76.97 (s). 31P-
{1H} NMR (CD2Cl2): δ -35.21 (s). IR (CD2Cl2): 3062 (w), 2989
(w), 2917 (w), 2009 (s), 1492 (w), 1467 (w), 1430 (w), 1384 (w),
1317 (w), 1265 (s), 1145 (s), 1031 (s), 954 (m), 865 (w), 748
(w), 684 (w), 570 (w), 553 (w), 516 (w). Anal. Calcd for C18H29F3-
IrO4PS: C, 34.78; H, 4.70. Found: C, 34.88; H, 4.74.
1
(CH3)3), 20.0 (s, p-methyl), 17.1 (d, J P-C ) 42.3 Hz, P(CH3)3),
9.7 (s, C5(CH3)5). 19F NMR (CD2Cl2): δ -76.93 (s). 31P{1H}
NMR (CD2Cl2): δ -43.86 (s). IR (CD2Cl2): 2015 (s), 1268 (s),
1147 (s), 1031 (s), 638 (s). FAB LRMS: m/z 551 ([Cp*(PMe3)-
Ir(2,4,6-trimethylphenyl)(CO)]+). Anal. Calcd for C24H35F3IrO4-
PS: C, 41.17; H, 5.04. Found: C, 40.77; H, 5.04.
[Cp *(P Me3)Ir (P h )(CO)][OTf] (6). Synthesis was per-
formed by employing the general procedure described above
using 118 mg (0.205 mmol) of 1 and 32.6 mg (0.308 mmol) of
benzaldehyde. Compound 6 was isolated (117 mg, 0.178 mmol)
as pale yellow crystals (87% yield) by crystallization from CH2-
Cl2/Et2O. Mp: 222-225 °C. 1H NMR (CD2Cl2, 400 MHz): δ
7.10 (m, 5H, Ph), 1.97 (d, 4J P-H ) 2.0 Hz, 15H, C5(CH3)5), 1.68
[Cp *(P Me3)Ir (2-(Z)-1-p h en ylp r op en yl)(CO)][OTf] (10).
Synthesis was performed by employing the general procedure
described above using 103 mg (0.179 mmol) of 1 and 39.2 mg
(0.268 mmol) of R-methylcinnamaldehyde. Compound 10 was
isolated (91.0 mg, 0.130 mmol) as a beige powder (73% yield)
by precipitation from CH2Cl2 solution by addition of pentane.
Mp: 87 °C dec. 1H NMR (CD2Cl2, 400 MHz): δ 7.4-7.1 (m,
5H, C6H5), 6.3 (s, 1H, dCHPh), 2.46 (br s, 3H, CCH3), 2.08 (d,
2
(d, J P-H ) 11.2 Hz, 9H, P(CH3)3). 13C{1H} NMR (CD2Cl2, 101
MHz): δ 169.3 (d, 2J P-C ) 12 Hz, CO), 141.0 (s, o-C6H5), 132.1
2
(s, p-C6H5), 127.2 (s, m-C6H5), 124.3 (d, J P-C ) 10.4 Hz,

Alkylation of Iridium
Organometallics, Vol. 19, No. 11, 2000 2141
2
4J P-H ) 2.0 Hz, 15H, C5(CH3)5), 1.86 (d, J P-H ) 11.2 Hz, 9H,
CH2Cl2 solution by addition of Et2O. mp ) 171-172 °C. 1H
P(CH3)3). 13C{1H} NMR (CD2Cl2, 101 MHz): δ 167.5 (d, J P-C
NMR (CD2Cl2, 400 MHz): δ 2.02 (d, J P-H ) 2.4 Hz, 15H, C5-
2
4
2
) 12.7 Hz, CO), 139.6 (s, i-C6H5), 136.7 (s, ) CHPh), 128.6 (s,
(CH3)5), 1.84 (d, J P-H ) 10.4 Hz, 9H, P(CH3)3), 1.48 (s, 9H,
o-C6H5), 128.4 (s, m-C6H5), 126.6 (s, p-C6H5), 125.4 (d, 2J P-C
)
C(CH3)3). 13C{1H} NMR (CD2Cl2, 101 MHz): δ 168.6 (d, J P-C
2
1
2
10.6 Hz, CCH3), 121.4 (q, J C-F ) 319 Hz, CF3), 103.8 (s, C5-
(CH3)5), 34.0 (s, CCH3), 15.5 (d, 1J P-C ) 42.6 Hz, P(CH3)3), 9.4
(s, C5(CH3)5). 19F NMR (CD2Cl2): δ -77.00 (s). 31P{1H} NMR
(CD2Cl2): δ -32.59 (s). IR (CD2Cl2): 2019 (s), 1384 (m), 1270
(s), 1222 (s), 1149 (s), 1031 (s), 958 (s), 638 (s). FAB HRMS:
m/z calcd for C23H33IrOP 549.1898, found 549.1901. Elemental
analysis was not performed for this compound, due to its
similarity to complexes 2-9, 14, and 15.
) 12.3 Hz, CO), 105.7 (d, J P-C ) 1.7 Hz, C5(CH3)5), 41.0 (s,
1
2
C(CH3)3), 18.6 (d, J P-C ) 39.9 Hz, P(CH3)3), 15.5 (d, J P-C
)
4.8 Hz, C(CH3)3), 10.5 (s, C5(CH3)5). 19F NMR (CD2Cl2): δ -77.0
(s). 31P{1H} NMR (CD2Cl2): δ -47.5 (s). IR (CD2Cl2): 2015 (s),
1267 (s), 1222 (m), 1145 (s), 1031 (s), 956 (m), 636 (m). FAB
LRMS: m/z 489 ([Cp*(PMe3)Ir(t-Bu)(CO)]+). Anal. Calcd for
C
19H34F3IrO4PS: C, 35.73; H, 5.37. Found: C, 35.37; H, 5.16.
[Cp *(P Me3)Ir (t-Bu )(CO)][BP h 4] (15). Compound 14 (134
[Cp *(P Me3)(Ir (CH3)(η2(C,C)-CH2dCHCHO)][OTf] (12).
In the glovebox, a 50 mL Schlenk flask was charged with 1
(98 mg, 0.169 mmol) and dichloromethane (6 mL). Acrolein
(14.2 mg, 0.254 mmol) was vacuum-transferred from CaSO4
into the reaction vessel. The reaction mixture was stirred at
room temperature for 10 days. The volatile materials were
removed in vacuo, and the remaining solids were washed with
diethyl ether (3 × 10 mL). The crude product was recrystallized
twice from dichloromethane/diethyl ether by vapor diffusion
at -30 °C to give 66 mg of 12 (63% yield) as a tan powder.
Mp: 211 °C. 1H NMR (CD2Cl2, 400 MHz): δ 8.23 (br d, 1H,
mg, 0.211 mmol) was dissolved in 10 mL of CH2Cl2. NaBPh4
(404 mg, 1.18 mmol) was added as a solid. The heterogeneous
reaction was stirred overnight and then filtered through Celite.
The volatile materials were removed in vacuo to give 167 mg
(0.207 mmol) of crude 15 in 98% yield. Complex 15 was
recrystallized (86% yield) from CH2Cl2/toluene and isolated as
1
pale yellow crystals. Mp: 200-201 °C. H NMR (CD2Cl2, 400
3
MHz): δ 7.31 (br s, 8H, o-C6H5), 7.03 (t, J H-H ) 6.0, 8H,
3
4
m-C6H5), 6.87 (t, J H-H ) 6.0, 4H, p-C6H5), 1.96 (d, J P-H
)
2.0 Hz, 15H, C5(CH3)5), 1.69 (d, 2J P-H ) 10.6 Hz, 9H, P(CH3)3),
1.47 (s, 9H, C(CH3)3). 13C{1H} NMR (CD2Cl2, 101 MHz): δ
3
3
3
2
1
CHO), 3.30 (dddd, J H-H ) 11.6 Hz, J H-H ) 7.2 Hz, J P-H
)
)
168.7 (d, J P-C ) 54.6 Hz, CO), 164.5 (1:1:1:1 q, J C-B ) 48.8
3
2
2
11.1 Hz, J H-H ) 14.4 Hz, 1H, CHCHO), 2.87 (ddd, J H-H
Hz, i-C6H5), 136.3 (s, C6H5), 125.9 (1:1:1:1 q, J C-B ) 2.8 Hz,
3
3
2
3.2 Hz, J H-H ) 11.6 Hz, J P-H ) 8.0 Hz, 1H, cis-CHdCH2),
o-C6H5), 122.1 (s, C6H5), 105.7 (d, J P-C ) 2.1 Hz, C5(CH3)5),
3
3
3
1
2.72 (ddd, J H-H ) 3.2 Hz, J H-H ) 7.2 Hz, J P-H ) 10.2 Hz,
41.1 (s, C(CH3)3), 18.7 (d, J P-C ) 39.8 Hz, P(CH3)3), 16.3 (d,
4
2J P-C ) 4.6 Hz, C(CH3)3), 10.6 (s, C5(CH3)5). 31P{1H} NMR (CD2-
Cl2): δ -45.9 (s). IR (CD2Cl2): 3050 (m), 3025 (m), 2996 (m),
2983 (m), 2915 (m), 2850 (m), 2024 (sh), 2005 (vs), 1579 (w),
1479 (m), 1427 (m), 1382 (m), 1363 (w), 1294 (w), 1130 (m),
1029 (w), 954 (s), 732 (s), 707 (s). FAB LRMS: m/z 489 ([Cp*
(PMe3)Ir(t-Bu)(CO)]+). Anal. Calcd for C42H53BIrOP: C, 62.43;
H, 6.49. Found C, 62.33; H, 6.55.
1H, trans-CHdCH2), 1.85 (d, J P-H ) 2.0 Hz, 15 H, C5(CH3)5),
2
3
1.47 (d, J P-H ) 8.4 Hz, 9H, P(CH3)3), 0.81 (d, J P-H ) 6.4 Hz,
3H, Ir-CH3). 13C{1H} NMR (CD2Cl2, 101 MHz): δ 191.9 (s,
2
CHO), 102.9 (d, J P-C ) 2.3 Hz, C5(CH3)5), 59.4 (s, CH), 37.8
(s, CH2), 11.5 (d, J P-C ) 42.5 Hz, P(CH3)3), 9.4 (s, C5(CH3)5),
1
-14.5 (d, 2J P-C ) 8.9 Hz, Ir-CH3). 19F NMR (CD2Cl2): δ -76.95
(s). 31P{1H} NMR (CD2Cl2): δ -25.08 (s). IR (CD2Cl2): 1677
(s), 1481 (w), 1429 (w), 1384 (m), 1268 (s), 1147 (s), 1031 (s),
960 (s), 636 (s). FAB LRMS: m/z 475 ([Cp*(PMe3)Ir(CH3)(η2-
(C,C)-CH2dCHCHO)]+). Anal. Calcd for C18H31F3IrO4PS: C,
34.66; H, 5.01. Found: C, 34.38; H, 5.02.
1-Ad a m a n ta n eca r boxa ld eh yd e (16). Although several
syntheses of 16 have been reported, a new and more conve-
nient synthesis is described here. A 100 mL three-necked flask,
fitted with a nitrogen inlet adapter and two addition funnels,
was charged with oxalyl chloride (15 mL, 6.62 mmol) and
cooled to -60 °C in a CHCl3/CO2 bath. One addition funnel
was charged with DMSO (0.94 mL, 13.2 mmol) and dichlo-
romethane (5 mL). The other addition funnel was charged with
1-adamantanemethanol (1.00 g, 6.02 mmol), dichloromethane
(10 mL), and DMSO (3 mL). The DMSO/CH2Cl2 mixture was
added to the cold oxalyl chloride dropwise over 3 min. The
resulting solution was stirred for 3 min. The DMSO/CH2Cl2/
1-adamantanemethanol solution was then added dropwise over
2 min, and the addition funnel was rinsed with dichlo-
romethane (2 mL), which was added to the reaction mixture.
The resulting reaction mixture was stirred for 15 min. Tri-
ethylamine (3.04 g, 3.56 mmol) was added to the clean addition
funnel and added dropwise to the reaction mixture over 5 min.
The resulting solution was stirred for 5 min. The reaction
vessel was removed from the CHCl3/CO2 bath and warmed to
room temperature. Water (40 mL) was added to the mixture
and stirred 15 min. The organic materials were extracted into
dichloromethane (3 × 30 mL). The combined organic layers
were back-extracted with saturated brine solution (40 mL),
dried over Na2SO4, and filtered, and the solvent was removed
in vacuo. The resulting yellow oil was purified by flash column
chromatography160 (silica, 95% hexanes, 5% EtOAc) to afford
the aldehyde as a white powder (0.59 g, 3.56 mmol) in 59%
[Cp *(P Me3)Ir (CHdCH2)(CO)][OTf] (13). In the glovebox,
a 10 mL glass vessel fitted with a Kontes high-vacuum
stopcock was charged with acrolein complex 12 (40 mg, 0.064
mmol) and dichloromethane (3 mL). The vessel was sealed and
placed in a 75 °C circulating bath for 24 h. After the reaction
mixture had cooled to 25 °C, the solvent was removed in vacuo
and the remaining solids were washed with diethyl ether (3
× 5 mL). The crude product was recrystallized twice from
dichloromethane/diethyl ether by vapor diffusion at -30 °C
to give 22 mg of 13 (57% yield) as a tan powder by precipitation
from CH2Cl2 solution by addition of pentane. Mp: 158-160
1
3
°C dec. H NMR (CD2Cl2, 400 MHz): δ 6.49 (dd, J H-H ) 9.2
2
3
Hz, J H-H ) 3.0 Hz, 1H, trans-CHdCH2), 6.40 (ddd, J H-H
)
3
3
16.3 Hz, J H-H ) 9.2 Hz, J H-P ) 6.9 Hz, 1H, CHdCH2), 5.47
3
2
(dd, J H-H ) 16.6 Hz, J H-H ) 3.0 Hz, 1H, cis-CHdCH2), 2.02
4
2
(d, J H-P ) 2.0 Hz, 15H, C5(CH3)5), 1.75 (d, J H-P ) 9.2 Hz,
9H, P(CH3)3). 13C{1H} NMR (CD2Cl2, 101 MHz): δ 167.6 (d,
2J C-P ) 11 Hz, CO), 129.0 (s, CHdCH2), 121.5 (q, J C-F ) 320
1
2
Hz, CF3), 118.2 (d, J C-P ) 12.1 Hz, CHdCH2), 103.4 (s, C5-
(CH3)5), 15.2 (d, J C-P ) 42.7 Hz, P(CH3)3), 9.4 (s, C5(CH3)5).
1
19F NMR (CD2Cl2): δ -77.0 (s). 31P{1H} NMR (CD2Cl2): δ
-33.8 (s). IR (CD2Cl2): 2981 (w), 2973 (w), 2919 (w), 2021 (s),
1575 (w), 1473 (w), 1421 (w), 1384 (m), 1294 (m), 1265 (s), 1224
(m), 1149 (s), 1031 (s), 954 (m), 638 (s), 516 (w). FAB LRMS:
m/z 459 ([Cp*(PMe3)Ir(CHdCH2)(CO)]+). FAB HRMS: m/z
calcd for C16H27IrOP 459.1429, found 459.1423. Elemental
analysis was not performed for this compound due to its
similarity to complexes 2-9, 14, and 15.
[Cp *(P Me3)Ir (t-Bu )(CO)][OTf] (14). Synthesis was per-
formed employing the general procedure described above using
135 mg (0.236 mmol) 1, and 22.4 mg (0.260 mmol) 2,2-
dimethylpropanal. Compound 14 was isolated (134 mg, 0.211
mmol) as a white powder (89% yield) by precipitation from
1
yield. H NMR (400 MHz, CD2Cl2): δ 9.29 (s, 1H, CHO), 2.05
(br m, 3H, â-CH), 1.77 (br m, 6H, R-CH2), 1.70 (br m, 6H,
δ-CH2); lit.161 δ 9.32 (s, 1H), 2.06 (m, 3H), 1.73 (m, 12H). 13C-
{1H} NMR: δ 206.0 (s, CHO), 45.1 (s, R-C), 36.9 (s, â-CH2),
(160) Still, W. C.; Kahn, M.; Mitra, A. J . Org. Chem. 1978, 43, 2923-
2925.
(161) Kar, A. K.; Lightner, D. A. J . Heterocycl. Chem. 1998, 35, 795-
804.

2142 Organometallics, Vol. 19, No. 11, 2000
Alaimo et al.
36.2 (s, γ-CH2), 27.9 (s, δ-CH); lit.162 δ 205.88, 41.75, 36.54,
35.83, 27.34. IR (CD2Cl2): 2900 (s), 2848 (s), 1726 (s), 1452
(m), 1384 (m), 1349 (m), 1288 (w), 1257 (m), 1193 (m), 1162
(m), 1112 (s), 1089 (s), 1058 (w), 987 (w), 928 (w), 810 (w), 650
(w); lit.162 νCO 1730.
(w), 1481 (sh), 1428 (s), 1381 (m), 1274 (s), 1222 (s), 1146 (s),
1070 (w), 1030 (s), 963 (sh), 945 (s), 861 (m), 802 (w), 750 (w),
732 (m), 678 (m), 637 (s), 571 (m), 516 (s). FAB HRMS: m/z
calcd for C17H36IrP2 495.1921, found 495.1917.
Cp *(P Me3)Ir (p-tolyl)(CHO) (28). In the glovebox, a 20 mL
scintillation vial was charged with 8 (36.2 mg, 0.054 mmol), 2
mL of THF, and a Teflon-coated stirbar. The mixture was
cooled to -30 °C in the glovebox freezer and LiBEt3H (1 M
THF solution, 54 µL, 0.054 mmol) was added by a 100 µL
syringe to the stirred solution over 30 s. The vial was returned
to the freezer and allowed to stand for 2 h. The mixture was
then warmed to 25 °C, and the solvent was removed in vacuo.
The remaining solids were extracted with pentane (4 × 2 mL),
and the solvent was removed in vacuo from the combined
pentane extracts to give 28 (23.5 mg, 0.045 mmol) in 84%
isolated yield. The resulting colorless residue was recrystal-
[Cp *(P Me3)Ir (1-a d a m a n t yl)(CO)][OTf] (17). Synthesis
was performed by employing the general procedure described
above using 107 mg (0.188 mmol) of 1 and 40.1 mg (0.244
mmol) of 1-adamantanecarboxaldehyde. Compound 17 was
isolated (97.1 mg, 0.136 mmol) as a pale yellow powder (72%
yield) by precipitation from CH2Cl2 solution by addition of
pentane. Mp: 125-126 °C. 1H NMR (CD2Cl2, 400 MHz): δ
4
2.19 (br m, 6H), 2.03 (br m, 9H), 1.99 (d, J P-H ) 2.0 Hz, 15H,
C5(CH3)5), 1.85 (d, 2J P-H ) 10.4 Hz, 9H, P(CH3)3). 13C{1H} NMR
2
(CD2Cl2, 101 MHz): δ 168.1 (d, J P-C ) 12.2 Hz, CO), 105.6
3
(s, C5(CH3)5), 53.1 (d, J P-C ) 2.2 Hz, â-CH2), 37.0 (s, δ-CH2),
1
2
1
lized in a single crop from dichloromethane in 71% yield. H
33.6 (s, γ-CH), 29.8 (d, J P-C ) 4.7 Hz, Ir-C), 18.4 (d, J P-C
)
3
39.8 Hz, P(CH3)3), 10.4 (s, C5(CH3)5). 19F NMR (CD2Cl2): δ
-76.91 (s). 31P{1H} NMR (CD2Cl2): δ -47.46 (s). IR (CD2Cl2):
2915 (m), 2850 (w), 2028 (s), 2021 (s), 1731 (w), 1639 (w), 1450
(m), 1384 (s), 1265 (s), 1149 (s), 1031 (s), 960 (m), 638 (s). FAB
LRMS: m/z 567 ([Cp*(PMe3)Ir(1-adamantyl)(CO)]+). HRMS
was not performed for this compound, since the cationic portion
is identical with that of complex 18.
NMR (CD2Cl2, 400 MHz): δ 13.8 (d, J P-H ) 1.7 Hz, 1H,
IrCHO), 6.82 (d, 3J H-H ) 7.7 Hz, 2H, C6H4CH3), 6.71 (d, 3J H-H
4
) 7.8 Hz, 2H, C6H4CH3), 2.22 (s, 3H, p-CH3), 1.71 (d, J P-H
)
1.4 Hz, 15H, C5(CH3)5), 1.39 (d, 2J P-H ) 10.4 Hz, 9H, P(CH3)3).
13C{1H} NMR (CD2Cl2, 101 MHz): δ 231.6 (br, IrCHO), 141.1
(s, o-C6H4CH3), 131.0 (s, p-C6H4CH3), 129.0 (s, m-C6H4CH3),
2
128.6 (d, J P-C ) 12.8 Hz, i-C6H4CH3), 98.4 (s, C5(CH3)5), 20.8
1
3
(s, C6H4CH3), 15.2 (d, J P-C ) 39.6 Hz, P(CH3)3), 9.0 (d, J P-C
) 12.4 Hz, C5(CH3)5). 19F NMR (CD2Cl2): δ -77.3 (s). 31P {1H}
NMR (CD2Cl2): δ -40.0 (s). IR (CD2Cl2): 2911 (s), 2864 (s),
2806 (m), 2732 (w), 2569 (w), 2518 (w), 2024 (m), 1978 (w),
1731 (w), 1600 (s), 1563 (m), 1499 (s), 1483 (m), 1455 (m), 1419
(m), 1378 (m), 1281 (m), 1224 (w), 1213 (w), 1156 (w), 1102
(w), 1071 (w), 1054 (w), 1031 (m), 1016 (w), 952 (s), 897 (w),
857 (w), 798 (m), 775 (m), 732 (m), 680 (w), 638 (m), 570 (w),
544 (w), 517 (w), 501 (w). Anal. Calcd for C21H32IrOP: C, 48.17;
H, 6.16. Found C, 47.80; H, 6.49.
[Cp *(P Me3)Ir (1-a d a m a n t yl)(CO)][B(3,5-(CF 3)2C6H 3)4]
(18). Compound 17 (271 mg, 0.379 mmol) was dissolved in 10
mL of CH2Cl2. NaBArf (1.0 g, 1.1 mmol) was added as a solid.
The heterogeneous reaction mixture was stirred overnight and
then filtered through Celite. The volatile materials were
removed in vacuo to give 536 mg (0.375 mmol) of crude 18 in
99% yield. Complex 18 was recrystallized from CH2Cl2/toluene
1
in 81% yield. Mp: 188-191 °C. H NMR (CD2Cl2, 400 MHz):
δ 7.72 (br s, 8H, o-C6H3(CF3)2), 7.56 (s, 4H, p-C6H3(CF3)2), 2.20
4
(br m, 6H), 1.97 (d, J P-H ) 2.0 Hz, 15H, C5(CH3)5), 1.88 (br
2
m, 9H), 1.79 (d, J P-H ) 10.4 Hz, 9H, P(CH3)3). 13C{1H} NMR
Cr ysta llogr a p h ic Stu d ies. Crystallographic details are
given in Table 4. Crystals of 9, 15, and 18 were mounted on
quartz fibers using Paratone N hydrocarbon oil. All measure-
ments were made on a Siemens SMART difffractometer with
graphite-monochromated Mo KR radiation. Frames corre-
sponding to an arbitrary hemisphere of data were collected
using ω scans of 0.30° counted for a total of 10 s each on 9
and 15 and 20 s each on 18. Data were integrated using the
program SAINT163 and were corrected for Lorentz and polar-
ization effects. No decay corrections were applied. Data were
analyzed for agreement and possible absorption using XPREP.164
An empirical absorption correction based on comparison of
redundant and equivalent reflections was applied using SAD-
2
(CD2Cl2, 101 MHz): δ 168.5 (d, J P-C ) 12.1 Hz, CO), 162.3
1
(1:1:1:1 q, J B-C ) 49.5 Hz, i-C6H3(CF3)2), 135.3 (br s, o-C6H3-
2
4
(CF3)2), 129.4 (qq, J F-C ) 31.2 Hz, J F-C ) 2.9 Hz, m-C6H3-
1
(CF3)2), 125.1 (q, J F-C ) 270.7 Hz, CF3), 118.0 (m, p-C6H3-
3
(CF3)2), 105.8 (d, J P-C ) 2.3 Hz, adam-â-CH2), 37.0 (s, adam-
2
δ-CH2), 33.9 (s, adam-γ-CH), 31.2 (d, J P-C ) 4.6 Hz, adam-
R-C), 18.6 (d, 1J P-C ) 40.0 Hz, P(CH3)3), 10.4 (s, C5(CH3)5). 19
F
NMR (CD2Cl2): δ -61.0 (s). 31P{1H} NMR (CD2Cl2): δ -48.0
(s). IR (CD2Cl2): 2931 (m), 2910 (m), 2013 (s), 1612 (m), 1456
(m), 1355 (s), 1278 (s), 1137 (s), 1020 (m), 954 (m), 887 (m),
838 (m), 744 (w), 734 (w), 715 (m), 682 (m), 670 (m). FAB
HRMS: m/z calcd for C24H39IrOP 567.2368, found 567.2382.
[Cp *(P Me3)2Ir (Me)][OTf] (20). Meth od 1. In the glovebox,
a Pyrex NMR tube was charged with 2 (9.4 mg, 0.016 mmol),
PMe3 (6.0 mg, 0.079 mmol), and 0.5 mL of CD2Cl2. The tube
was then fitted with a Cajon adaptor and flame-sealed in vacuo
on a high-vacuum line after two freeze-pump-thaw degas
ABS164 (9, Tmax ) 0.49, Tmin ) 0.28; 15, Tmax ) 0.69, Tmin
)
0.48; 18, Tmax ) 0.83, Tmin ) 0.64). The structures were solved
by direct methods and expanded using Fourier techniques.
Hydrogen atoms were included in calculated idealized positions
but not refined. Plots of ∑w(|Fo| - |Fc|)2 versus |Fo|, reflection
order in data collection, (sin θ)/λ, and various classes of indices
showed no unusual trends. All calculations were performed
using the teXsan164 crystallographic software package of
Molecular Structure Corp.
For complex 9, the cationic portion was found to be disor-
dered between two sites. Only the Ir(2) and P(2) atoms were
located in the minor site of the cation. All non-hydrogen atoms
were refined anisotropically, except for Ir(2) and P(2), which
were refined isotropically. The population of the majority
iridium atom, Ir(1), was allowed to vary, and the populations
of Ir(2), P(1), and P(2) were tied to Ir(1); the occupancies of
Ir(2) and P(2) were constrained to be (1 - occ(Ir(1))), and the
occupancy of P(1) was constrained to equal the occupancy of
Ir(1). The isotropic thermal parameters of Ir(2) and P(2) were
1
cycles. The tube was photolyzed for 2 h at 10 °C. The H and
31P{1H} NMR data matched the data for independently
synthesized material exactly.
Meth od 2. Complex 20 was synthesized independently as
follows. In the glovebox, a 20 mL scintillation vial was charged
with 1 (29.3 mg, 0.516 mmol) and 2 mL of CH2Cl2. To this
was added PMe3 (8.0 µL, 0.775 mmol). When it was mixed,
the solution rapidly turned colorless. Removal of the volatile
materials in vacuo, followed by precipitation from dichlo-
romethane by addition of pentane, afforded 20 (31.5 mg, 0.490
1
mmol) in 95% isolated yield. H NMR (CD2Cl2, 400 MHz): δ
1.79 (t, 4J P-H ) 1.9 Hz, 15H, C5(CH3)5), 1.54 (m, 18H, P(CH3)3),
3
0.16 (t, J P-H ) 6.3 Hz, 3H, IrCH3). 13C{1H} NMR (CD2Cl2,
101 MHz): δ 98.1 (s, C5(CH3)5), 17.4 (m, P(CH3)3), 9.6 (s, C5-
2
(CH3)5), -27.8 (t, J P-C ) 31.6 Hz, IrCH3). 19F NMR (CD2Cl2):
δ -77.3 (s). 31P{1H} NMR (CD2Cl2): δ -42.3 (s). IR (CD2Cl2):
(163) SAINT: SAX Area-Detector Integration Program; Version
4.024; Siemens Industrial Automation, Inc., Madison, WI, 1995.
(164) For references providing details of the crystallography tech-
niques, see: Alaimo, P. J .; Bergman, R. G. Organometallics 1999, 18,
2707-2717.
2965 (s), 2921 (s), 2829 (m), 2290 (w), 1729 (m), 1640 (w), 1621
(162) Olah, G. A.; Wang, Q. Synthesis 1992, 1090-1092.

Alkylation of Iridium
Organometallics, Vol. 19, No. 11, 2000 2143
Ta ble 4. Cr ysta l Da ta Collection a n d Refin em en t P a r a m eter s for Com p lexes 9, 15, a n d 18
9
15
18
empirical formula
fw
C
24H35F3IrO4PS
C42H53BIrOP
807.88
C24H39IrOP
1522.12
699.79
cryst habit
cryst size, mm
cryst syst
lattice type
a, Å
colorless blocks
0.09 × 0.18 × 0.35
triclinic
primitive
8.5800(4)
12.7278(6)
13.0668(6)
78.050(1)
70.971(1)
87.312(1)
1319.41(10)
P1h (No. 2)
2
pale yellow
0.15 × 0.16 × 0.30
orthorhombic
primitive
20.6674(4)
12.2900(2)
29.7698(7)
pale blades
0.08 × 0.15 × 0.33
monoclinic
C-centered
41.536(2)
b, Å
c, Å
12.6740(6)
25.017(1)
R, deg
â, deg
109.960(1)
γ, deg
V, Å3
7561.6(2)
Pca21 (No. 29)
8
12378.7(9)
C2/c (No. 15)
8
space group
Z value
D
calcd, g/cm3
1.761
1.419
1.633
F000
temp, °C
692.00
-148.0
52.62
10.0
46.6
3280.00
-121.0
36.14
10.0
52.0
6064.00
-130.0
23.03
20.0
53.7
µ(Mo KR), cm-1
exposure time, s/frame
2θmax, deg
no. of rflns measd
total
6732
35 069
30 085
unique
3743
14 193
11 622
no. of observns
no. of variables
rfln./param ratio
R;a Rw;b Rall
3518
315
11.17
0.024; 0.033; 0.026
9152
828
11.05
0.027; 0.029; 0.048
5376
754
7.13
0.059; 0.064; 0.128
GOF indicator
max resid density, e/Å3
min resid density, e/Å3
1.34
0.63
-1.67
1.01
0.85
-0.80
1.95
1.37
-1.11
a
b
2
R ) ∑||Fo| - |Fc||/∑|Fo|. Rw ) [∑w(|Fo| - |Fc|)2/∑w|Fo| ]1/2; w ) 1/σ2(Fo).
also constrained to be equal. This model resulted in 5.0%
occupancies of Ir(2) and P(2).
For complex 18, there are two orientations of the molecule
in each site in the ratio 0.216(3):0.784(3). Although the
1-adamantyl and the CO ligands appear to be fully ordered,
the Cp* and the PMe3 ligands are disordered. The majority
and minority components of the Ir position are clearly sepa-
rated, but the positions of the PMe3 and the Cp* atoms are
thoroughly intertwined. Occupancy of all disordered atoms was
adjusted to follow the refinement of the Ir(1) and Ir(2)
occupancies. The Cp* ligands were refined as rigid groups
(using a planar Cp with the methyl groups out of plane by 0.2
Å). Only one atom has been assigned to the minority compo-
nent of the PMe3 ligand, P(2), causing the carbon count to be
deficient in the refinement. The other fractional carbon atoms
on the PMe3 ligand are apparently masked by the electron
density of the major component of the Cp* model.
For complex 15, although the anions and the iridium atoms
of the cations are related by a noncrystallographic inversion
center, addition of the inversion center to the space group
operations of Pca21 does not yield a higher symmetry space
group. A view of the asymmetric unit is shown in the
supplementary information with only the central atoms la-
beled. Refinement of the Flack parameter in a test run
indicated that the structure reported was the correct enan-
tiomorph. Solution and refinement of the structure was
complicated by the pseudo-inversion, by disorder of the iridium
center of one cation, and by the presence of a second crystal
in the sample (unrecognized at first). Non-hydrogen atoms
were refined anisotropically with an occupancy parameter for
the disordered iridium atom. Following discovery of the
contribution of the second crystal, the six worst reflections with
Fo > Fc were removed from the data set. A model including
apparent disorder on both iridium atoms drastically reduced
the residuals; however, this model could not be refined as well
as one including a larger disorder component on only one of
the iridium centers. The assignment of disorder to only one of
the two molecules is also consistent with the thermal param-
eters of the other atoms in the two molecules. The final
refinement included the occupancy factors of Ir(1) and Ir(3),
linked so that they summed to 1.0. The final occupancy ratio
Ir(3):Ir(1) was 0.31:0.69. The reduced quality of the data, due
to the adhering crystal and the disorder of the structure,
indicates that the geometric data should be analyzed with care.
The nondisordered molecule clearly shows the expected three-
legged piano-stool coordination geometry of the Ir atom by the
Cp*, PMe3, CO, and tert-butyl ligands. The majority component
of the disordered cation has the same basic geometry, except
that the CO ligand is positioned transoid (rather than cisoid)
to one of the Cp* methyl groups.
Ack n ow led gm en t. We thank Dr. Frederick J . Hol-
lander of the UC Berkeley X-ray Diffraction Facility
(CHEXRAY) for determination of the crystal structures
of 9, 15, and 18. We are grateful for support of this work
by the Director, Office of Energy Research, Office of
Basic Energy Sciences, Chemical Sciences Division, U.S.
Department of Energy, under Contract no. DE-AC03-
76SF00098. We also express our gratitude to the J ohn
Simon Guggenheim Memorial Foundation for a fellow-
ship to R.G.B.
Su p p or tin g In for m a tion Ava ila ble: Listings of X-ray
structural data for complexes 9, 15, and 18. This material is
available free of charge via the Internet at http://pubs.acs.org.
OM9910064