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A series of hydrido(vinyl)iridium(III) complexes that are thermodynamically more stable than their olefin iridium(I) isomers

DOI: 10.1021/om0505099

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Organometallics p. 5127 - 5139 (2005)

Update date:2022-08-05

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Authors:

Dirnberger, ThomasDirnberger, Thomas

Werner, HelmutWerner, Helmut

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Article abstract of DOI:10.1021/om0505099

The reaction of the in situ generated cyclooctene iridium(I) derivative trans-[IrCl(C8H14)-(PiPr3)2] with methyl vinyl ketone and other Michael systems RCH=C(R′)C(O)R″ (R = H, Me, Ph, OMe; R′ = H, Me, iPr; R″ = H, Me, OMe, NH2, NMe2) resulted in the formation of the octahedral hydrido(vinyl)iridium(III) complexes [IrH(Cl){κ2(C,O)-C(R)= C(R′)C(R″)=O}-(PiPr3)2] (2-13) with the vinyl ligand coordinated in a bidentate fashion. Treatment of trans-[IrCl(C 8H14)(PiPr3)2] with methyl acrylate and either dimethyl fumarate or dimethyl maleate afforded the iridium(I) compounds trans-[IrCl(η2-RCH=CHCO2Me)(PiPr 3)2] (15, 16), which thermally or photochemically rearrange to the thermodynamically more stable iridium(III) isomers [IrH(Cl){κ2(C,O)-C(R)=CHC(OMe)=O}(PiPr3) 2] (17, 18) by intramolecular C-H activation. The reaction of trans-[IrCl(C8H14)(PiPr3)2] with PhCH=CHC(O)Ph gave a 1:1 mixture of the isomeric iridium(III) complexes [IrH(Cl){K2(C,O)-C(Ph)=CHC(Ph)=O}(PiPr3)2] (19) and [IrH(Cl){κ2(C,O)-C6H4C(CH=CHPh)=O} (PiPr3)2] (20), which were separated by column chromatography. From trans-[IrCl(C8H14)(PiPr 3)2] and acrylic acid both [IrH(Cl)- {κ2(C,O)-CH=CHC(OH)=O}(PiPr3)2] (21) and [IrH(Cl){κ2(O,O)-O2CCH=CH2}(PiPr 3)2] (22) were obtained. While the attempted hydrogenation of [IrH(Cl){κ2(C,O)-CH=CHC(Me)=O}-(PiPr3) 2] (2) with Pd/C as the catalyst led to the formation of [IrH 2(Cl)(PiPr3)2] (24) and ethyl methyl ketone, the same starting material reacted with a solution of Cl2 in chloroform to give the dichloro vinyl complex [IrCl2{κ 2(C,O)-CH=C(Cl)C(Me)=O}(PiPr3)2] (27) in virtually quantitative yield. The reaction of both 2 and [IrH(I) {κ2(C,O)-CH=CHC(Me)=O}(PiPr3)2] (29) with CO afforded the carbonyl compounds [IrH(X){η1-(Z)-CH=CHC(O)Me} (CO)(PiPr3)2] (31, 32) by partial opening of the chelate bond. Similarly to the Ir(PiPr3)2 counterparts, a series of (olefin)iridium(I) and hydrido(vinyl)iridium(III) compounds with Ir(PMetBu2)2 as a molecular unit were also prepared. Most remarkably, treatment of trans-[IrCl(η2-CH2= CHC(O)H)(PMetBu2)2] (43) with in situ generated trans-[IrCl(C8H14)(PMetBu2)2] led to a clean cleavage of coordinated acrolein to CO and ethene and afforded a 1:1 mixture of trans-[IrCl(CO)(PMetBu2)2] (44) and trans-[IrCl(C2H4)(PMetBu2)2] (45), respectively.

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Full text of DOI:10.1021/om0505099

Organometallics 2005, 24, 5127-5139  
5127  
A Series of Hydrido(vinyl)iridium(III) Complexes That  
Are Thermodynamically More Stable than Their Olefin  
Iridium(I) Isomers†  
Thomas Dirnberger and Helmut Werner*  
Institut fu¨r Anorganische Chemie der Universita¨t Wu¨rzburg, Am Hubland,  
D-97074 Wu¨rzburg, Germany  
Received June 21, 2005  
The reaction of the in situ generated cyclooctene iridium(I) derivative trans-[IrCl(C8H14)-  
(PiPr3)2] with methyl vinyl ketone and other Michael systems RCHdC(R′)C(O)R′′ (R ) H,  
Me, Ph, OMe; R′ ) H, Me, iPr; R′′ ) H, Me, OMe, NH2, NMe2) resulted in the formation of  
the octahedral hydrido(vinyl)iridium(III) complexes [IrH(Cl){κ2(C,O)-C(R)dC(R′)C(R′′)dO}-  
(PiPr3)2] (2-13) with the vinyl ligand coordinated in a bidentate fashion. Treatment of trans-  
[IrCl(C8H14)(PiPr3)2] with methyl acrylate and either dimethyl fumarate or dimethyl maleate  
afforded the iridium(I) compounds trans-[IrCl(η2-RCHdCHCO2Me)(PiPr3)2] (15, 16), which  
thermally or photochemically rearrange to the thermodynamically more stable iridium(III)  
isomers [IrH(Cl){κ2(C,O)-C(R)dCHC(OMe)dO}(PiPr3)2] (17, 18) by intramolecular C-H  
activation. The reaction of trans-[IrCl(C8H14)(PiPr3)2] with PhCHdCHC(O)Ph gave a 1:1  
mixture of the isomeric iridium(III) complexes [IrH(Cl){κ2(C,O)-C(Ph)dCHC(Ph)dO}(PiPr3)2]  
(19) and [IrH(Cl){κ2(C,O)-C6H4C(CHdCHPh)dO}(PiPr3)2] (20), which were separated by  
column chromatography. From trans-[IrCl(C8H14)(PiPr3)2] and acrylic acid both [IrH(Cl)-  
{κ2(C,O)-CHdCHC(OH)dO}(PiPr3)2] (21) and [IrH(Cl){κ2(O,O)-O2CCHdCH2}(PiPr3)2] (22)  
were obtained. While the attempted hydrogenation of [IrH(Cl){κ2(C,O)-CHdCHC(Me)dO}-  
(PiPr3)2] (2) with Pd/C as the catalyst led to the formation of [IrH2(Cl)(PiPr3)2] (24) and  
ethyl methyl ketone, the same starting material reacted with a solution of Cl2 in chloroform  
to give the dichloro vinyl complex [IrCl2{κ2(C,O)-CHdC(Cl)C(Me)dO}(PiPr3)2] (27) in virtually  
quantitative yield. The reaction of both 2 and [IrH(I){κ2(C,O)-CHdCHC(Me)dO}(PiPr3)2]  
(29) with CO afforded the carbonyl compounds [IrH(X){η1-(Z)-CHdCHC(O)Me}(CO)(PiPr3)2]  
(31, 32) by partial opening of the chelate bond. Similarly to the Ir(PiPr3)2 counterparts, a  
series of (olefin)iridium(I) and hydrido(vinyl)iridium(III) compounds with Ir(PMetBu2)2 as  
a molecular unit were also prepared. Most remarkably, treatment of trans-[IrCl(η2-CH2d  
CHC(O)H)(PMetBu2)2] (43) with in situ generated trans-[IrCl(C8H14)(PMetBu2)2] led to a  
clean cleavage of coordinated acrolein to CO and ethene and afforded a 1:1 mixture of trans-  
[IrCl(CO)(PMetBu2)2] (44) and trans-[IrCl(C2H4)(PMetBu2)2] (45), respectively.  
Introduction  
complex [(η5-C5Me5)IrH(C6H11)(PMe3)] reacts with ethene  
by elimination of cyclohexane to give both [(η5-C5Me5)-  
IrH(CHdCH2)(PMe3)] and [(η5-C5Me5)Ir(η2-C2H4)(PMe3)].  
The surprising result, later supported by MO calcula-  
tions,3 was that the (ethene)iridium(I) compound is the  
thermodynamically favored product and is not an in-  
termediate in the formation of the hydrido vinyl isomer.  
Moreover, Perutz et al. demonstrated by IR spectro-  
scopic studies that photolysis of [(η5-C5H5)Ir(η2-C2H4)2]  
in an argon matrix leads to the formation of the iridium-  
(III) complex [(η5-C5H5)IrH(CHdCH2)(η2-C2H4)], which  
isomerizes at 0 °C to regenerate the starting material.4  
Following this pioneering work,2-4 it was shown by  
Transition-metal compounds with olefinic ligands  
belong to the prototypical metal π complexes. Until the  
mid 1980s it was the general belief that, if a precursor  
of the general composition [M(L)n] (where (L)n repre-  
sents the whole set of ligands coordinated to the metal  
center) reacts with the olefin CH2dCHR, only an  
interaction between M and the carbon-carbon double  
bond would occur. However, in the course of their  
extensive studies on C-H bond activation,1 Bergman  
and co-workers reported that the cyclohexyl hydrido  
† Dedicated to Professor Peter Pauson on the occasion of his 80th  
birthday, with our best wishes and congratulations for his scientific  
achievements.  
(1) Reviews: (a) Bergman, R. G. Science 1984, 223, 902-908. (b)  
Jones, W. D.; Feher, F. J. Acc. Chem. Res. 1989, 22, 91-100. (c) Perutz,  
R. N. Chem. Soc. Rev. 1993, 22, 361-369. (d) Arndtsen, B. A.; Bergman,  
R. G.; Mobley, T. A.; Peterson, T. H. Acc. Chem. Res. 1995, 28, 154-  
162. (e) Shilov, A. E.; Shul’pin, G. B. Chem. Rev. 1997, 97, 2879-2932.  
(f) Guari, Y.; Sabo-Etienne, S.; Chaudret, B. Eur. J. Inorg. Chem. 1999,  
1047-1055. (g) Jia, C.; Kitamura, T.; Fujiwara, Y. Acc. Chem. Res.  
2001, 34, 633-639. (h) Crabtree, R. H. Dalton Trans. 2001, 2437-  
2450.  
(2) (a) Stoutland, P. O.; Bergman, R. G. J. Am. Chem. Soc. 1985,  
107, 4581-4582. (b) Stoutland, P. O.; Bergman, R. G. J. Am. Chem.  
Soc. 1988, 110, 5732-5744.  
(3) Silvestre, J.; Calhorda, M. J.; Hoffmann, R.; Stoutland, P. O.;  
Bergman, R. G. Organometallics 1986, 5, 1841-1851.  
(4) (a) Haddleton, D. M.; Perutz, R. N. J. Chem. Soc., Chem.  
Commun. 1986, 1734-1736. (b) Bell, T. W.; Haddleton, D. M.;  
McCamley, A.; Partridge, M. G.; Perutz, R. N.; Willner, H. J. Am.  
Chem. Soc. 1990, 112, 9212-9226.  
10.1021/om0505099 CCC: $30.25 © 2005 American Chemical Society  
Publication on Web 09/13/2005  
5128 Organometallics, Vol. 24, No. 21, 2005  
Dirnberger and Werner  
Scheme 1a  
several groups that in general the conversion of the  
ethene transition-metal compound [M(η2-C2H4)(L)n] into  
the hydrido vinyl isomer [MH(CHdCH2)(L)n] is ther-  
modynamically an uphill process,5 provided that the  
labile hydrido vinyl complex is not stabilized either by  
the presence of hard ancillary ligands6 or by the addition  
of CO, CH3CN, etc. to the metal center.7  
In the present article, we report that the order of  
thermodynamic stability [IrH(CHdCH2)(L)n] < [Ir(η2-  
C2H4)(L)n] found by Bergman, Perutz, and others can  
be reversed if instead of ethene the corresponding  
ethene derivative CH2dCHR containing an aldehyde,  
ketone, acid, ester, or amido group R is used as the  
olefinic substrate. In this case, the hydrido(vinyl)-  
iridium(III) species is stabilized by an additional linkage  
of the functionality to the metal center and does not  
rearrange to the (olefin)iridium(I) isomer. Some pre-  
liminary results of this work have already been com-  
municated.8  
Results and Discussion  
a L ) PiPr3.  
Preparation of Hydrido(vinyl) Iridium(III) Com-  
plexes From Olefins by C-H Activation. The (cy-  
clooctene)iridium(I) derivative trans-[IrCl(C8H14)(PiPr3)2],  
generated in situ from 1 and 4 equiv of triisopropyl-  
phosphine in benzene,9 reacts with methyl vinyl ketone  
even at room temperature. After addition of the sub-  
strate, a quick change of color from yellow to red  
occurred, indicating that the weakly bound cycloolefin  
is displaced by the unsaturated ketone. The observation  
of a ν(CdO) band at 1650 cm-1 in the IR spectrum of  
the supposed intermediate trans-[IrCl{η2-CH2dCHC-  
(O)Me}(PiPr3)2], compared with 1690 cm-1 for free  
CH2dCHC(O)Me, supports this assumption. If the solu-  
tion is subsequently stirred for 30 min, the color changes  
again, in this case from red to yellow, and after removal  
of the solvent and chromatographic workup the hydrido-  
(vinyl)iridium(III) complex 2 is isolated as a yellow solid  
vinylic protons in R- and â-positions. For the hydrido  
1
ligand, the H NMR spectrum shows a resonance at δ  
-23.67 ppm, which is split into a triplet due to 1H-31P  
coupling. The appearance of one singlet in the 31P NMR  
spectrum confirms that the phosphine ligands are trans  
disposed. The 13C NMR spectrum of 2 displays the  
signal for the CdO carbon atom at δ 207.1 ppm and  
the resonances for the vinyl carbon atoms at δ 198.8  
and 133.2 ppm, respectively. Due to the cis disposition  
of the R-C atom and the PiPr3 groups, the signal at δ  
198.8 ppm is split into a triplet, while the resonances  
at δ 207.1 and 133.2 ppm appear as singlets.  
The most prominent feature in the IR spectrum of 2  
is the ν(CdO) stretching mode at 1540 cm-1, which is  
shifted by ca. 150 cm-1 to lower wavenumbers compared  
with free CH2dCHC(O)Me. Since this shift is consistent  
with a coordination of the carbonyl group to the metal  
center, an octahedral geometry for compound 2 can be  
assumed. In this context it should be mentioned that  
Esteruelas, Oro, et al. reported the preparation of the  
four-coordinate iridium(I) complex [Ir(κ2-acac){η2-CH2d  
CHC(O)Me}(PCy3)] from [Ir(κ2-acac)(C8H14)(PCy3)] and  
methyl vinyl ketone and its thermal rearrangement to  
a mixture of two six-coordinate hydrido(vinyl)iridium-  
(III) stereoisomers.11 Regarding the supposed interme-  
diate trans-[IrCl{η2-CH2dCHC(O)Me}(PiPr3)2], initially  
formed in the reaction of trans-[IrCl(C8H14)(PiPr3)2] with  
methyl vinyl ketone, we note that we had previously  
isolated the rhodium counterpart trans-[RhCl{η2-CH2d  
CHC(O)Me}(PiPr3)2], which slowly rearranges at room  
temperature to give the C-H activation product [RhH-  
(Cl){κ2(C,O)-CHdCHC(Me)dO}(PiPr3)2] in high yield.12  
The in situ generated starting material trans-[IrCl-  
(C8H14)(PiPr3)2] reacts not only with methyl vinyl ketone  
but also with the related derivatives RCHdCHC(O)Me  
(R ) OMe, Me, Ph) to give the corresponding hydrido-  
(vinyl)iridium(III) complexes 3-5 in 75-89% yield  
(Scheme 1). These reactions are considerably slower  
1
in 85% yield (Scheme 1). The H NMR spectrum of 2  
displays in the low-field region two doublets at δ 10.72  
and 6.80 ppm, which, in agreement with previous  
results by Nesmeyanov et al.,10 are assigned to the  
(5) (a) Baker, M. V.; Field, L. D. J. Am. Chem. Soc. 1986, 108, 7433-  
7434. (b) Bell, T. W.; Brough, S.-A.; Partridge, M. G.; Perutz, R. N.;  
Rooney, A. D. Organometallics 1993, 12, 2933-2941. (c) Bianchini, C.;  
Barbaro, P.; Meli, A.; Peruzzini, M.; Vacca, A.; Vizza, F. Organome-  
tallics 1993, 12, 2505-2514. (d) Siegbahn, P. E.; Blomberg, M. R. A.;  
Svenson, M. J. Am. Chem. Soc. 1993, 115, 1952-1958.  
(6) (a) Ghosh, C. K.; Hoyano, J. K.; Kreutz, R.; Graham, W. A. G. J.  
Am. Chem. Soc. 1989, 111, 5480-5481. (b) Ferna´ndez, M. J.; Rodriguez,  
M. J.; Oro, L. A.; Lahoz, F. J. J. Chem. Soc., Dalton Trans. 1989, 2073-  
2076. (c) Gutie´rrez, E.; Monge, A.; Nicasio, M. C.; Poveda, M. L.;  
Carmona, E. J. Am. Chem. Soc. 1994, 116, 791-792. (d) Alvarado, Y.;  
Daff, P. J.; Pe´rez, P. J.; Poveda, M. L.; Sa´nchez-Delgado, R.; Carmona,  
E. Organometallics 1996, 15, 2192-2194. (e) Alvarado, Y.; Boutry, O.;  
Gutie´rrez, E.; Monge, A.; Nicasio, M. C.; Poveda, M. L.; Pe´rez, P. J.;  
Ru´ız, C.; Bianchini, C.; Carmona, E. Chem. Eur. J. 1997, 3, 860-873.  
(f) Gutie´rrez-Puebla, E.; Monge, A.; Nicasio, M. C.; Pe´rez, P. J.; Poveda,  
M. L.; Rey, L.; Ru´ız, C.; Carmona, E. Inorg. Chem. 1998, 37, 4538-  
4546.  
(7) (a) Schulz, M.; Werner, H. Organometallics 1992, 11, 2790-2795.  
(b) Papenfuhs, B.; Mahr, N.; Werner, H. Organometallics 1993, 12,  
4244-4246. (c) Werner, H.; Papenfuhs, B.; Steinert, P. Z. Anorg. Allg.  
Chem. 2001, 627, 1807-1814.  
(8) Werner, H.; Dirnberger, T.; Schulz, M. Angew. Chem. 1988, 100,  
993-994; Angew. Chem., Int. Ed. Engl. 1988, 27, 948-950.  
(9) (a) Schulz, M. Diploma Thesis, Universita¨t Wu¨rzburg, 1988. (b)  
Dziallas, M. Ph.D. Thesis, Universita¨t Wu¨rzburg, 1988.  
(10) Nesmeyanov, A. N.; Rybinskaya, M. I.; Rybin, L. V.; Kaganov-  
ich, V. S.; Petrovskii, P. V. J. Organomet. Chem. 1971, 31, 257-267.  
(11) Castarlenas, R.; Esteruelas, M. A.; Mart´ın, M.; Oro, L. A. J.  
Organomet. Chem. 1998, 564, 241-247.  
(12) Dirnberger, T.; Werner, H. Chem. Ber. 1992, 125, 2007-2014.  
Hydrido(vinyl)iridium(III) Complexes  
Organometallics, Vol. 24, No. 21, 2005 5129  
Scheme 2a  
than the reaction leading to 2, and thus the respective  
reaction mixture has to be stirred for 2-3 h at 80 °C.  
In contrast to the conditions employed to obtain 3 and  
4, for the preparation of 5 an excess of PhCHdCHC-  
(O)Me has to be used. If the solution containing the  
starting material is treated with the ketones at room  
temperature and stirred for 24 h, in addition to the  
hydrido vinyl compounds 3-5 the dihydrido complex  
[IrH2(Cl)(PiPr3)2] is formed as a byproduct.13 Typical  
spectroscopic features of 3-5 are the 1H NMR resonance  
for the hydride at δ -23.6 to -24.4 ppm and the 13C  
NMR signal for the R-carbon atom of the vinylic unit at  
δ 207.4 to 214.1 ppm, both appearing as triplets. In  
comparison with 2, the resonance of the vinylic â-carbon  
atom of 3 is shifted significantly upfield and that of 5  
significantly downfield, thus illustrating the influence  
of the electron-donating and electron-withdrawing sub-  
stituents. The 31P NMR spectra of 3-5 display only one  
signal in the region between δ 6.9 to 16.0 ppm, indicat-  
ing that not only in 2 but also in 3-5 the phosphine  
ligands are trans disposed.  
The reaction of trans-[IrCl(C8H14)(PiPr3)2] with ac-  
rolein proceeds under the same conditions as that with  
methyl vinyl ketone and affords nearly quantitatively  
the expected hydrido vinyl complex 6. The corresponding  
R,â-unsaturated aldehydes CH2dC(R′)C(O)H (R′ ) Me,  
iPr) are less reactive than acrolein and react with the  
starting material at 80 °C to give the C-H activation  
products 7 and 8 as orange, only slightly air-sensitive  
solids in 83-85% yield. Although several transition-  
metal compounds with acrolein are known,14 we failed  
to detect the supposed intermediate trans-[IrCl{η2-  
CH2dCHC(O)H}(PiPr3)2] by IR or NMR spectroscopy.  
The 1H NMR spectrum of 6 displays the hydride  
resonance as a doublet of triplets due to 1H-1H coupling  
with the aldehyde proton and 1H-31P coupling with the  
phosphorus nuclei. In the spectra of 7 and 8, the  
1H-31P coupling cannot be observed.  
Methyl methacrylate and acid amides such as CH2d  
CHC(O)NH2, CH2dC(Me)C(O)NH2, PhCHdCHC(O)-  
NH2, and CH2dCHC(O)NMe2 also react with trans-  
[IrCl(C8H14)(PiPr3)2] by oxidative addition to form the  
corresponding hydrido vinyl complexes 9-13 in good to  
excellent yields. At room temperature, the acrylic acid  
amide CH2dCHC(O)NH2 is much more reactive than  
the dimethylamido derivative CH2dCHC(O)NMe2, and  
thus, for the preparation of 11 (see Scheme 1) a long  
time of reaction is necessary. If the reaction mixture of  
trans-[IrCl(C8H14)(PiPr3)2] and CH2dCHC(O)NMe2 is  
stirred for 3 h at 80 °C (i.e., under the same conditions  
as employed for the preparation of 9 and 13), in addition  
to the hydrido vinyl complex 11 the dihydrido compound  
24 (see Scheme 4) is equally formed. Since in the IR  
spectra of the products obtained from methyl methacry-  
late and acid amides the CdO stretching mode appears  
at around 1555-1570 cm-1, there is no doubt that the  
a L ) PiPr3.  
additional linkage of the vinyl ligand takes place via  
the CdO and not the OMe or NR2 functionality.  
In contrast to acrolein and CH2dC(R′)C(O)H (R′ )  
Me, iPr), the substituted aldehydes RCHdCHC(O)H (R  
) Me, Ph) react with the in situ generated cyclooctene  
derivative trans-[IrCl(C8H14)(PiPr3)2] to give predomi-  
nantly the carbonyl iridium(I) complex 14 instead of the  
expected hydrido(vinyl)iridium(III) compounds [IrH(Cl)-  
{κ2(C,O)-C(R)dCHCHdO}(PiPr3)2]. In agreement with  
recent studies by Bianchini et al. on the reactivity of  
hydridorhodium(I) complexes toward RCHdCHC(O)H  
(R ) Me, Ph),15 we assume that the formation of 14  
proceeds via the five-coordinate acyl hydrido intermedi-  
ate [IrH(Cl){η1-C(O)CHdCHR}(PiPr3)2], which rear-  
ranges to the six-coordinate hydrido vinyl species [IrH-  
(Cl)(η1-CHdCHR)(CO)(PiPr3)2]. In the final step, this  
species affords the carbonyl complex 14 and the olefin  
RCHdCH2 by reductive elimination.  
Treatment of a solution of the starting material trans-  
[IrCl(C8H14)(PiPr3)2] in benzene with methyl acrylate  
led to the formation of the olefin iridium(I) complex 15  
(Scheme 2), which is stable at room temperature and,  
after evaporation of the solvent and recrystallization  
from pentane, has been isolated as a red solid in 79%  
yield. In a similar way, by using either dimethyl  
fumarate or dimethyl maleate as the substrate, com-  
pound 16 was formed. On the basis of the observation  
that in the 1H NMR spectrum of 16 two signals  
(doublets of virtual triplets) appear for the diaste-  
reotopic methyl protons of the PiPr3 units, we conclude  
that independent of whether (Z)- or (E)-RCHdCHR (R  
) CO2Me) is used as the reagent, the olefinic ligand of  
16 possesses an E configuration. The 31P NMR spectrum  
of 16 displays a single resonance, which supports the  
proposed structure.  
Either on warming at 80 °C (for 15) or on irradiation  
in benzene (for 16), the respective olefin compounds  
rearrange nearly quantitatively to the hydrido vinyl  
isomers 17 and 18. Diagnostic features of 18 are the  
1
two resonances for the OCH3 protons in the H NMR  
and the two pairs of signals for the CdO and the OCH3  
carbon atoms in the 13C NMR spectrum. The proposed  
stereochemistry of 18 with the phosphine ligands and  
the chloride and the R-carbon atom of the vinyl group  
in trans disposition has been confirmed by an X-ray  
(13) Werner, H.; Wolf, J.; Ho¨hn, A. J. Organomet. Chem. 1985, 287,  
395-407.  
(14) (a) Schrauzer, G. N. J. Am. Chem. Soc. 1959, 81, 5310-5312.  
(b) Fritz, H. P.; Schrauzer, G. N. Chem. Ber. 1961, 94, 650-659. (c)  
Weiss, E.; Stark, K.; Lancaster, J. E.; Murdoch, H. D. Helv. Chim. Acta  
1963, 46, 288-297. (d) Tate, D. P.; Buss, A. A.; Augl, J. M.; Ross, B.  
L.; Grasselli, J. G.; Ritchey, W. M.; Knoll, F. J. Inorg. Chem. 1965, 4,  
1323-1328. (e) Kawaguchi, S.; Ogura, T. Inorg. Chem. 1966, 5, 844-  
846.  
(15) Bianchini, C.; Meli, A.; Peruzzini, M.; Ramirez, J. A.; Vacca,  
A.; Vizza, F.; Zanobini, F. Organometallics 1989, 8, 337-345.  
5130 Organometallics, Vol. 24, No. 21, 2005  
Dirnberger and Werner  
Scheme 4a  
Scheme 3a  
a L ) PiPr3.  
structure analysis.16 The chelate ring is nearly planar  
with a maximum deviation of 0.013 and 0.011 Å for the  
metal-bonded oxygen and carbon atoms out of the plane.  
The distance between iridium and the vinylic R-carbon  
atom is 2.005(7) Å and is comparable to that in the  
hydrido vinyl complex [IrH(CHdCH2)(κ2-acac)(PiPr3)2]  
(2.02(1) Å).7b The P-Ir-P axis is significantly bent  
(166.11(6)°) in the direction of the smallest (hydride)  
ligand, which is probably a consequence of steric repul-  
sion between the isopropyl groups and the substituents  
at the vinyl moiety. The bending is quite similar to that  
found for [IrH(CHdCH2)(κ2-acac)(PiPr3)2] (165.3(1)°).7b  
Dual Behavior of Other Michael Systems. In  
contrast to cinnamic aldehyde, PhCHdCHC(O)H, which  
upon treatment with trans-[IrCl(C8H14)(PiPr3)2] affords  
the carbonyl complex 14, the related phenyl ketone  
PhCHdCHC(O)Ph reacts with the in situ generated  
starting material trans-[IrCl(C8H14)(PiPr3)2] in toluene  
at 80 °C to give an orange-red product which consists  
of the two isomers 19 and 20 (Scheme 3). They are  
formed in a ratio of about 1:1 and can be separated by  
column chromatography. The NMR data of the “ex-  
pected” isomer 19 are quite similar to those of compound  
5, which was prepared from trans-[IrCl(C8H14)(PiPr3)2]  
and PhCHdCHC(O)Me (see Scheme 1). Typical spec-  
troscopic features of the second isomer 20, being formed  
by aromatic and not by olefinic C-H activation, are a  
triplet resonance for the ipso carbon atom of the C6H4  
ring at δ 165.2 ppm and two nearby singlets for the  
olefinic carbon atoms at δ 118.9 and 118.5 ppm, respec-  
tively. In contrast, the vinylic ring carbon atoms of 19  
resonate in the 13C NMR spectrum at δ 209.4 and 148.4  
ppm. The hydride signal appears in the 1H NMR  
spectrum of 19 at δ -22.88 ppm and in that of 20 at δ  
-23.98 ppm. Both signals are split into triplets with the  
1H-31P coupling constants being nearly the same.  
Similarly to the ketone PhCHdCHC(O)Ph, acrylic  
acid also reacts with the cyclooctene derivative trans-  
[IrCl(C8H14)(PiPr3)2] to afford the two isomeric products  
21 and 22 in about equal quantities (Scheme 4). In this  
case, the reaction took place in toluene at room tem-  
perature and the products were separated by fractional  
crystallization. While the hydrido vinyl complex 21 is a  
white, only moderately air-sensitive solid, the hydrido  
carboxylato compound 22 is a yellow oil that has been  
characterized by IR and NMR spectroscopy. Diagnostic  
for 21 are the ν(OH) stretching mode in the IR spectrum  
at 3435 cm-1, the two doublets for the vinyl protons at  
δ 9.72 and 6.87 ppm in the 1H NMR spectrum, and the  
singlet resonance at δ 17.0 ppm in the 31P NMR  
a L ) PiPr3.  
spectrum. Whereas in the 1H NMR spectrum of 21 the  
triplet for the hydride is observed at δ -25.23 ppm, the  
corresponding triplet resonance in the H NMR spec-  
trum of 22 is significantly shifted upfield and appears  
at δ -34.80 ppm.  
1
Under conditions similar to those used for the prepa-  
ration of 21 and 22, crotonic acid reacts with trans-[IrCl-  
(C8H14)(PiPr3)2] to give a single product, which according  
to the analytical and spectroscopic data is the hydrido  
carboxylato complex 23 (see Scheme 4). The IR spectrum  
of 23 displays for the asymmetric OCO stretching mode  
a characteristic absorption at 1520 cm-1, which indi-  
cates that the carboxylate unit is coordinated to iridium  
in a chelating fashion.17 Note that in the IR spectrum  
of 21 the asymmetric ν(OCO) band is observed at 1510  
cm-1. The reactions of methyl crotonate and methyl  
cinnamate, RCHdCHCO2Me (R ) Me, Ph), with trans-  
[IrCl(C8H14)(PiPr3)2] proceed not by C-H activation of  
the olefinic substrate but yield instead, besides traces  
of undefined compounds, the dihydrido complex 24 as  
the main component.  
Studies on the Reactivity of the Hydrido(vinyl)-  
iridium(III) Complexes. In contrast to the hydrido-  
(vinyl)ruthenium(II) derivatives [RuH{κ2(C,O)-CHd  
C(Me)C(OR)dO}(PPh3)3] (R ) Me, Et, iPr), which react  
with H2 at room temperature and 1 bar to give [RuH2-  
(H2)(PPh3)3] and the corresponding ester Me2CHCO2R,18  
the hexacoordinate iridium(III) complex 2 is completely  
inert under a hydrogen atmosphere. Even when the  
pressure of H2 is increased to 70 bar, no reaction occurs.  
However, if a solution of 2 in benzene is stirred in the  
presence of hydrogen and catalytic amounts of Pd on  
charcoal at 40 °C, the starting material affords the  
dihydride 24 and the saturated ketone EtC(O)Me by  
cleavage of the metal-carbon bond (Scheme 5). Al-  
though it is conceivable that in the initial step of this  
reaction a hydrogenation of the vinyl unit takes place,  
we failed to detect the supposed intermediate [IrH(Cl)-  
{κ2(C,O)-CH2CH2C(Me)dO}(PiPr3)2] by H NMR or IR  
spectroscopy.  
1
(17) (a) Robinson, S. D.; Uttley, M. F. J. Chem. Soc., Dalton Trans.  
1973, 1912-1920. (b) Deacon, G. B.; Phillips, R. J. Coord. Chem. Rev.  
1980, 33, 227-250. (c) Oldham, C. In Comprehensive Coordination  
Chemistry; Wilkinson, G., Gillard, R. D., McCleverty, J. A., Eds.;  
Pergamon: New York, 1987; Vol. 2, pp 435-459.  
(18) Komiya, S.; Ito, T.; Cowie, M.; Yamamoto, A.; Ibers, J. A. J.  
Am. Chem. Soc. 1976, 98, 3874-3884.  
(16) Schulz, M. Ph.D. Thesis, Universita¨t Wu¨rzburg, 1991.  
Hydrido(vinyl)iridium(III) Complexes  
Organometallics, Vol. 24, No. 21, 2005 5131  
Scheme 5a  
a L ) PiPr3.  
Scheme 6a  
Scheme 7a  
a L ) PiPr3.  
which are quite similar to those of 27. Regarding the  
formation of 26 and 27 from 2 and Cl2, we note that  
owing to previous work by Vrieze et al. the reaction of  
[IrH(Cl){κ2(C,N)-C(Ph)dCHCHdNiPr}(PPh3)2] with chlo-  
rine yields only the monochlorinated derivative [IrH-  
(Cl){κ2(C,N)-C(Ph)dC(Cl)CHdNiPr}(PPh3)2], which does  
not react with excess Cl2 by splitting of the Ir-H bond.21  
The hydrido iodo complex 29 was prepared in 80%  
yield by salt metathesis of 2 with an excess of NaI in  
acetone at room temperature (Scheme 7). Compound 29  
is a yellow solid which has been characterized not only  
by elemental analysis and spectroscopic techniques but  
also by X-ray crystallography.16 As expected, the mo-  
lecular structure of 29 is similar to that of 18 and also  
has the two phosphines and the halide and the R-carbon  
atom of the vinyl group trans disposed. The bending of  
the P-Ir-P axes is 164.2(2)° and is thus slightly less  
than in 18. The relatively short Ir-C distance of 1.83-  
(3) Å indicates that for 29 a second canonical form with  
an iridium-carbon double bond contributes to the  
structure for the five-membered ring.  
a L ) PiPr3.  
Attempts to prepare the dihydrido complex [IrH2-  
{κ2(C,O)-CHdCHC(Me)dO}(PiPr3)2] by treatment of the  
hydrido chloro compound 2 with LiAlH4, NaBH4, or  
LiHBEt3 also were unsuccessful. Independent of whether  
an equimolar amount or an excess of the hydride donor  
was used, both a substitution of the chloride and a  
replacement of the vinyl unit occurred. The sole iridium-  
containing product is the pentahydrido complex 25,  
which was first prepared by Clerici et al. from [HPiPr3]-  
19  
[IrCl4(PiPr3)2] and LiAlH4 and later shown by Gold-  
man and Halpern to be an appropriate catalyst for the  
selective hydrogenation of alkynes to alkenes.20  
The reaction of compound 2 with a solution of Cl2 in  
chloroform yields a mixture of two products, of which  
the dichloroiridium(III) derivative 27 dominates (Scheme  
6). The minor component still contains a hydrido ligand,  
as indicated by the high-field resonance in the 1H NMR  
spectrum at δ -24.26 ppm. Since this chemical shift  
differs only slightly from that of the precursor 2, we  
assume that the byproduct is the hydrido chloro complex  
26. Treatment of the reaction mixture with an excess  
of chlorine in CHCl3 leads to the conversion of 26 to 27  
and gives this compound as a red air-stable solid in  
nearly quantitative yield. Both the mass spectrum and  
the 13C NMR spectrum of 27 confirm that in the course  
of the chlorination reaction the Ir-C bond is not split  
and the chelate ring remains intact. A characteristic  
difference between the intermediate 26 and the final  
product 27 is observed in the 31P NMR spectrum of the  
mixture, which shows a singlet for 26 at δ 9.1 ppm and  
a second singlet for 27 at δ -9.4 ppm. The reaction of  
the hydrido chloro compound 6 with Cl2 in chloroform  
gives the dichloro complex 28, the spectroscopic data of  
To possibly generate a hydrido(vinyl)iridium(III) com-  
plex containing a monodentate vinyl ligand, we also  
displaced the chloride in compound 2 with acetate.  
Treatment of a solution of 2 in acetone with an equimo-  
lar amount of CH3CO2Ag at room temperature led to  
the formation of 30, which, according to the IR and NMR  
data, is the sole reaction product. In contrast to what  
we expected, the acetate ligand is probably not coordi-  
nated in a bidentate but in a monodentate fashion, as  
indicated by the position of the corresponding CdO  
stretching mode in the IR spectrum at 1625 cm-1 17  
In  
.
1
the H NMR spectrum of 30, the IrH and the vinylic  
protons resonate at about the same chemical shift as  
those of the hydrido iodo complex 29, which is in  
agreement with the proposed structure.  
A cleavage of the Ir-O bond of the five-membered  
chelate ring occurs, if solutions of 2 or 29 in benzene  
are treated with CO at 50 bar for 48 h at room  
temperature. After the pressure is released and the  
solvent evaporated, pale yellow (31) or yellow (32) air-  
(19) Clerici, M. G.; di Gioacchino, S.; Maspero, F.; Perrotti, E.;  
Zanobi, A. J. Organomet. Chem. 1975, 84, 379-388.  
(20) Goldman, A. S.; Halpern, J. J. Organomet. Chem. 1990, 382,  
237-253.  
(21) van Baar, J. F.; Klerks, J. M.; Overbosch, P.; Stufkens, D. J.;  
Vrieze, K. J. Organomet. Chem. 1976, 112, 95-103.  
5132 Organometallics, Vol. 24, No. 21, 2005  
Dirnberger and Werner  
Scheme 9a  
Scheme 8a  
a L ) PiPr3.  
Scheme 10a  
a L ) PiPr3.  
stable microcrystalline solids are isolated in 80-90%  
1
yield (Scheme 8). The H NMR spectra of 31 and 32  
display in the low-field region two signalssone doublet  
of doublet of triplets at about δ 8.8 ppm and a doublet  
of triplets at about δ 6.8 ppmswhich are assigned to  
3
the vinylic protons in R- and â-positions. The J(H,H)  
coupling constant of ca. 12 Hz indicates that the two  
protons at the CdC double bond are cis disposed. Due  
to the different trans influences of oxygen and CO, the  
hydride resonance appears for 31 at δ -8.14 ppm and  
for 32 at δ -9.68 ppm and is thus shifted by 15.5 to  
14.4 ppm downfield in comparison with the chelate  
complexes 2 and 29. A significant difference also exists  
in the chemical shift of the 13C NMR signal for the IrCH  
carbon atom, which appears for 2 at δ 198.8 ppm and  
for 31 at δ 144.7 ppm.  
While a solid sample of 31 is thermally rather stable  
and decomposes at 146 °C, warming a solution of 31 in  
benzene for 2 h at 80 °C leads to reductive elimination  
of methyl vinyl ketone and to the formation of 14 as  
the only detectable iridium-containing product. Quite  
remarkably, the carbonyl complex 14 is also generated  
upon stirring a solution of 6 in mesitylene for 3 h at  
160 °C. Regarding the mechanism of this reaction, it is  
conceivable that in the initial step a partial opening of  
the chelate ring occurs, which is followed by elimination  
of acrolein. Under the reaction conditions, a fragmenta-  
tion of acrolein to C2H4 and CO probably takes place  
and the carbon monoxide finally stabilizes the remain-  
ing [IrCl(PiPr3)2] fragment to give 14.  
a L ) PMetBu2.  
carbonyl hydrido complex 33 were obtained (Scheme 9).  
The molar conductivity Λ in nitromethane of 79.6 Ω-1  
cm2 mol-1 confirmed the presence of a 1:1 electrolyte.  
Typical spectroscopic features of 33 are the two 1H NMR  
resonances for the vinylic protons at δ 10.17 and 7.50  
ppm, the hydride signal at δ -20.68 ppm, and the  
singlet in the 31P NMR spectrum at δ 25.5 ppm,  
indicating that, similarly to 2, also in 33 the phosphine  
ligands are trans disposed. The IR spectrum of 33 shows  
a strong band for the CO ligand at 2050 cm-1 and a  
medium-to-strong absorption for the ν(CdO) stretching  
mode at 1565 cm-1. The latter is shifted by 25 cm-1 to  
higher wavenumbers in comparison with 2.  
(Olefin)iridium(I) and Hydrido(vinyl)iridium-  
(III) Complexes with [Ir(PMetBu2)2] as a Molecu-  
lar Unit. Taking into consideration that occasionally  
even small changes in the size and symmetry of tertiary  
phosphines lead to significant differences in the reactiv-  
ity of the corresponding phosphine-transition-metal  
complexes, a series of (olefin)iridium(I) and hydrido-  
(vinyl)iridium(III) compounds with Ir(PMetBu2)2 instead  
of Ir(PiPr3)2 as a molecular building block were also  
prepared. The general result is that ketones RCHd  
CHC(O)Me (R ) H, OMe), aldehydes CH2dC(R)C(O)H  
(R ) Me, iPr), and acrylic acid amide react with a  
mixture of 1 and PMetBu2 in benzene to give the  
hexacoordinate hydrido(vinyl) complexes 34-38 in ex-  
cellent yield (Scheme 10). Although we have no convinc-  
ing evidence that upon addition of a 4-5-fold excess of  
PMetBu2 to a solution of 1 the cyclooctene derivative  
To obtain a coordinatively unsaturated hydrido(vinyl)-  
iridium(III) complex, which could be a useful precursor  
for addition and/or insertion reactions, we attempted to  
abstract the chloro ligand from 2 by treatment with a  
-
PF6 salt. Whereas the starting material 2, dissolved  
in acetone or dichloromethane, is relatively inert in the  
presence of KPF6, the reaction of 2 with AgPF6 yields,  
besides AgCl, an ill-defined product that possibly con-  
tains the required compound [IrH{κ2(C,O)-CHdCHC-  
(Me)dO}(PiPr3)2]PF6. However, if the reaction of 2 with  
KPF6 (or AgPF6) was carried out under a CO atmo-  
sphere, a quick change of color from yellow to off-white  
occurred, and after filtration through a column of Al2O3,  
removal of the solvent, and recrystallization from  
CH2Cl2/hexane white air-stable crystals of the cationic  
Hydrido(vinyl)iridium(III) Complexes  
Organometallics, Vol. 24, No. 21, 2005 5133  
Scheme 11a  
Scheme 12a  
a L ) PMetBu2.  
a L ) PMetBu2.  
A surprising result was obtained when the acrolein  
complex 43 reacted with the in situ generated compound  
trans-[IrCl(C8H14)(PMetBu2)2]. After the reaction mix-  
ture was stirred for 30 min in benzene at room temper-  
ature and the solvent evaporated in vacuo, an orange  
trans-[IrCl(C8H14)(PMetBu2)2] is formed, we assume  
that in analogy to the corresponding reaction of 1 with  
PiPr3 such an intermediate is generated.9b After addi-  
tion of the Michael system to this intermediate, a  
stepwise change of color from yellow to red and then  
from red to yellow occurred, indicating that en route to  
the thermodynamically preferred iridium(III) complexes  
34-38 the isomeric iridium(I) compounds trans-[IrCl-  
{η2-RCHdC(R′)C(O)R′′}(PMetBu2)2] were probably  
formed.  
With methyl acrylate and either dimethyl fumarate  
or dimethyl maleate the expected olefin complexes 39  
and 40 were prepared and characterized by elemental  
analysis and spectroscopic means. The NMR data of 40  
are very similar to those of the PiPr3 counterpart, and  
thus there is no doubt that, independent of whether (E)-  
or (Z)-RCHdCHR (R ) CO2Me) is used as the precursor,  
the (dimethyl fumarate)iridium(I) compound is gener-  
ated. Either on heating at 80 °C (in the case of 39) or  
on irradiation (in the case of 40), the olefin complexes  
rearrange to the hydrido(vinyl)iridium(III) isomers 41  
and 42, which are also isolated in excellent yields.  
1
solid was isolated, which according to the H and 31P  
NMR spectra consisted of an 1:1 mixture of the iridium-  
(I) complexes 44 and 45 (Scheme 12). The olefin com-  
pound 45 was identified by comparison of the spectro-  
scopic data with that of an authentic sample prepared  
from trans-[IrCl(C8H14)(PMetBu2)2] and ethene. To ex-  
plain the formation of the two products, we assume that  
the labile cyclooctene derivative partly dissociates to  
generate the coordinatively unsaturated intermediate  
[IrCl(PMetBu2)2], which attacks the ligated acrolein  
possibly at the CdO bond to give both the metal  
carbonyl 44 and the olefin complex 45. Alternatively, it  
is also conceivable that in the initial step the acrolein  
compound 43 is converted to 44 and ethene, which then  
reacts with trans-[IrCl(C8H14)(PMetBu2)2] by ligand  
displacement to afford 45 and cyclooctene.  
Conclusions  
While we failed to detect the supposed intermediate  
trans-[IrCl{η2-CH2dCHC(O)H}(PiPr3)2] in the reaction  
of trans-[IrCl(C8H14)(PiPr3)2] with acrolein, we suc-  
ceeded in isolating the Ir(PMetBu2)2 counterpart 43  
(Scheme 11). For this purpose, the reaction mixture of  
trans-[IrCl(C8H14)(PMetBu2)2] and CH2dCHC(O)H was  
stirred only for a few minutes at room temperature and  
then quickly worked up as described for 15. Compound  
43 is a red, practically air-stable solid, the composition  
of which has been confirmed by elemental analysis and  
spectroscopic techniques. Diagnostic for the coordinated  
acrolein in 43 are the doublet resonance at δ 9.25 ppm  
for the aldehyde proton and the two signals at δ 3.40  
The present investigation has shown that iridium(I)  
compounds of the general composition trans-[IrCl(C8H14)-  
(PR3)2] (PR3 ) PiPr3, PMetBu2) containing a labile  
cyclooctene ligand react with substituted olefins CH2d  
CHR′, where R′ is an aldehyde, ketone, carboxylic acid,  
carboxylic ester, or carboxylic amide functionality, to  
give hydrido(vinyl)iridium(III) complexes in high yields.  
These hydrido(vinyl)iridium(III) complexes are defi-  
nitely (in the case of 17, 18, 41, and 42) or probably (in  
the case of 2-13, 19-21, and 34-38) formed via the  
olefin iridium(I) intermediates trans-[IrCl(η2-CH2d  
CHR′)(PR3)2], which, however, are thermodynamically  
less stable than the IrH(CHdCHR′) isomers. The high  
energy barrier, which had previously been observed for  
most of the reactions involving a C-H activation of a  
coordinated olefin, is obviously reduced if the CdC  
double bond bears an electron-withdrawing substituent  
such as C(O)H, C(O)R, C(O)OH, C(O)OR, C(O)NH2, and  
C(O)NMe2. The formation of the hydrido(vinyl)iridium-  
(III) complexes is certainly facilitated by the coordina-  
tion of the CdO oxygen atom to the metal center, thus  
leading to an unusually stable chelate system. It is  
noteworthy indeed that the five-membered IrC3O ring  
in compounds such as 2 and 6 even remains intact if  
these starting materials are treated with excess Cl2. A  
1
and 1.54 ppm for the olefinic protons in the H NMR  
spectrum. The 31P nuclei resonate at δ 5.9 ppm, the  
chemical shift being similar to that of 39. Attempts to  
convert the olefin complex 43 to the hydrido vinyl isomer  
[IrH(Cl){κ2(C,O)-CHdCHCHdO}(PMetBu2)2] resulted  
in the formation of the iridium(I) carbonyl 44. We  
assume that the mechanism of this reaction is similar  
to that proposed for the formation of 14 from trans-[IrCl-  
(C8H14)(PiPr3)2] and RCHdCHC(O)H, including an acyl-  
(hydrido)iridium(III) species as an intermediate. In this  
context we note that the half-sandwich-type compound  
[(η5-C5Me5)Ir(CH3)(OTf)(PMe3)] reacts with acrolein to  
give the olefin complex [(η5-C5Me5)Ir(CH3){η2-CH2d  
CHC(O)H}(PMe3)]OTf, which upon warming afforded  
the iridium(III) carbonyl derivative [(η5-C5Me5)Ir(CHd  
CH2)(CO)(PMe3)]OTf by elimination of methane.22  
(22) Alaimo, P. J.; Arndtsen, B. A.; Bergman, R. G. J. Am. Chem.  
Soc. 1997, 119, 5269-5270.  
5134 Organometallics, Vol. 24, No. 21, 2005  
Dirnberger and Werner  
2.50 (m, 6 H, PCHCH3), 2.19 (br s, 3 H, C(O)CH3), 1.30, 1.16  
(both dvt, N ) 13.4, J(H,H) ) 7.0 Hz, 18 H each, PCHCH3),  
-23.62 (t, J(P,H) ) 16.0 Hz, 1 H, IrH). 13C NMR (50.3 MHz,  
CDCl3): δ 213.7 (t, J(P,C) ) 6.2 Hz, IrC(OMe)), 203.6 (s,  
CdO), 107.9 (s, IrCHdCH), 56.9 (s, OCH3), 24.7 (s, C(O)CH3),  
24.2 (vt, N ) 27.3 Hz, PCHCH3), 19.1, 18.9 (both s, PCHCH3).  
31P NMR (36.3 MHz, C6D6): δ 16.0 (s, d in off-resonance).  
Preparation of [IrH(Cl){κ2(C,O)-C(Me)dCHC(Me)dO}-  
(PiPr3)2] (4). This compound was prepared analogously as  
described for 2, using 1 (160 mg, 0.17 mmol), PiPr3 (160 µL,  
0.80 mmol), and MeCHdCHC(O)Me (0.34 µL, 0.35 mmol) as  
starting materials. The reaction mixture was stirred for 2 h  
at 80 °C. A yellow microcrystalline solid was obtained: yield  
169 mg (75%); mp 183 °C dec. Anal. Calcd for C23H50ClIrOP2:  
C, 43.69; H, 7.97. Found: C, 43.60; H, 8.21. MS (70 eV): m/z  
(Ir) 632 (M+, 21), 548 (M+ - MeCHdCHC(O)Me, 57), 84  
(MeCHdCHC(O)Me+, 100). IR (KBr): ν(IrH) 2255, ν(CdO)  
partial opening of the chelate bond only occurs if  
precursors such as 2 and 29 are treated with carbon  
monoxide under severe conditions, which could be due  
to the preferred ability of iridium to coordinate a CO  
ligand.23  
Experimental Section  
All reactions were carried out under an atmosphere of argon  
by Schlenk techniques. The starting materials [IrCl(C8H14)2]2  
(1),24 trans-[IrCl(N2)(PPh3)2] (A),25 and PMetBu2 were pre-  
26  
pared as described in the literature. PiPr3 was a commercial  
product from Strem. NMR spectra were recorded on JEOL FX  
90 Q, Bruker AC 200, and Bruker AMX 400 instruments at  
room temperature, if not otherwise stated. IR spectra were  
recorded on a Perkin-Elmer 1420 infrared spectrometer and  
mass spectra on a Varian MAT CH 7 instrument. The molar  
conductivity ΛM was determined in nitromethane. Melting  
points were measured by DTA. Abbreviations used: s, singlet;  
d, doublet; t, triplet; q, quartet; sept, septet; m, multiplet; br,  
broadened signal. The term vt indicates a virtual triplet, with  
1
1550 cm-1. H NMR (200 MHz, CDCl3): δ 6.58 (s, 1 H, IrC-  
(Me)dCH), 2.44 (s, 3 H, IrCCH3), 2.36 (m, 6 H, PCHCH3), 2.12  
(t, J(P,H) ) 1.3 Hz, 3 H, C(O)CH3), 1.18, 0.98 (both dvt, N )  
13.3, J(H,H) ) 7.0 Hz, 18 H each, PCHCH3), -24.35 (t, J(P,H)  
) 16.2 Hz, 1 H, IrH). 13C NMR (50.3 MHz, CDCl3): δ 214.1 (t,  
J(P,C) ) 5.3 Hz, IrCH), 205.7 (s, CdO), 133.8 (s, IrCHdCH),  
37.3 (s, IrCCH3), 24.6 (s, C(O)CH3), 24.4 (vt, N ) 27.4 Hz,  
PCHCH3), 19.8, 18.8 (both s, PCHCH3). 31P NMR (36.3 MHz,  
C6D6): δ 12.1 (s, d in off-resonance).  
3
5
1
3
N ) J(P,H) + J(P,H) or J(P,C) + J(P,C).  
Preparation of [IrH(Cl){κ2(C,O)-CHdCHC(Me)dO}-  
(PiPr3)2] (2). A suspension of 1 (120 mg, 0.13 mmol) in  
benzene (5 mL) was treated under continuous stirring first  
with PiPr3 (120 µL, 0.60 mmol) and then with methyl vinyl  
ketone (23 µL, 0.26 mmol) at room temperature. After the  
reaction mixture was stirred for 30 min, a yellow solution was  
obtained. The solvent was evaporated in vacuo, the oily residue  
was dissolved in benzene/hexane (6 mL; 1:2), and the solution  
was chromatographed on Al2O3 (neutral, activity grade V,  
length of column 8 cm). With benzene/hexane (1:2) a yellow  
fraction was eluted, which was concentrated in vacuo until the  
first crystals precipitated. After hexane (5 mL) was added, the  
solution was stored at -78 °C for 12 h. A yellow microcrys-  
talline solid was formed, which was separated from the mother  
liquor, washed twice with small amounts of hexane (0 °C), and  
dried: yield 141 mg (85%); mp 167 °C. Anal. Calcd for  
C22H48ClIrOP2: C, 42.74; H, 7.83. Found: C, 42.67; H, 7.72.  
MS (70 eV): m/z (Ir) 618 (M+, 29), 548 (M+ - CH2dCHC(O)-  
Me, 44), 458 (M+ - PiPr3, 24), 70 (CH2dCHC(O)Me+, 100). IR  
Preparation of [IrH(Cl){κ2(C,O)-C(Ph)dCHC(Me)dO}-  
(PiPr3)2] (5). This compound was prepared analogously as  
described for 2, using 1 (160 mg, 0.17 mmol), PiPr3 (160 µL,  
0.80 mmol), and PhCHdCHC(O)Me (149 mg, 1.00 mmol) as  
starting materials. The reaction mixture was stirred for 3 h  
at 80 °C. An orange microcrystalline solid was obtained: yield  
221 mg (89%); mp 159 °C dec. Anal. Calcd for C28H52ClIrOP2:  
C, 48.44; H, 7.35. Found: C, 48.18; H, 7.57. MS (70 eV): m/z  
(Ir) 694 (M+, 3), 548 (M+ - PhCHdCHC(O)Me, 13), 146  
(PhCHdCHC(O)Me+, 100). IR (KBr): ν(IrH) 2245, ν(CdO)  
1535 cm-1. 1H NMR (90 MHz, CDCl3): δ 7.91, 7.21 (both m, 5  
H, C6H5), 2.43 (m, 6 H, PCHCH3), 2.31 (t, J(P,H) ) 1.5 Hz, 3  
H, C(O)CH3), 1.11, 1.03 (both dvt, N ) 13.7, J(H,H) ) 7.3 Hz,  
18 H each, PCHCH3), -23.75 (t, J(P,H) ) 16.8 Hz, 1 H, IrH),  
signal of IrCHdCH proton probably covered by signals of the  
phenyl protons. 13C NMR (50.3 MHz, CDCl3): δ 207.4 (t, J(P,C)  
) 5.1 Hz, IrC), 205.9 (s, CdO), 147.7 (s, IrCdCH), 131.2, 130.8,  
129.5, 127.5 (all s, C6H5), 25.0 (vt, N ) 27.1 Hz, PCHCH3),  
19.8, 19.3 (both s, PCHCH3), signal of C(O)CH3 methyl carbon  
atom probably covered by signal of PCHCH3 carbons. 31P NMR  
(36.3 MHz, C6D6): δ 6.9 (s, d in off-resonance).  
1
(KBr): ν(IrH) 2230, ν(CdO) 1540 cm-1. H NMR (200 MHz,  
CDCl3): δ 10.72 (d, J(H,H) ) 7.3 Hz, 1 H, IrCH), 6.80 (d,  
J(H,H) ) 7.3 Hz, 1 H, IrCHdCH), 2.37 (m, 6 H, PCHCH3),  
2.24 (br s, 3 H, C(O)CH3), 1.21, 1.04 (both dvt, N ) 13.5, J(H,H)  
) 7.0 Hz, 18 H each, PCHCH3), -23.67 (t, J(P,H) ) 15.8 Hz,  
1 H, IrH). 13C NMR (50.3 MHz, CDCl3): δ 207.1 (s, CdO),  
198.8 (t, J(P,C) ) 6.1 Hz, IrCH), 133.2 (s, IrCHdCH), 24.9 (s,  
C(O)CH3), 24.4 (vt, N ) 27.4 Hz, PCHCH3), 19.1, 18.1 (both s,  
PCHCH3). 31P NMR (36.3 MHz, C6D6): δ 18.9 (s, d in  
off-resonance).  
Preparation of [IrH(Cl){κ2(C,O)-CHdCHCHdO}(PiPr3)2]  
(6). This compound was prepared analogously as described for  
2, using 1 (140 mg, 0.15 mmol), PiPr3 (150 µL, 0.75 mmol),  
and acrolein (0.20 µL, 0.30 mmol) as starting materials. A  
yellow microcrystalline solid was obtained: yield 155 mg  
(82%); mp 165 °C dec. Anal. Calcd for C21H46ClIrOP2: C, 41.74;  
H, 7.67. Found: C, 41.65; H, 7.70. MS (70 eV): m/z (Ir) 604  
(M+, 27), 548 (M+ - CH2dCHC(O)H, 31), 444 (M+ - PiPr3,  
10), 56 (CH2dCHC(O)H+, 100). IR (KBr): ν(IrH) 2250,  
Preparation of [IrH(Cl){κ2(C,O)-C(OMe)dCHC(Me)d  
O}(PiPr3)2] (3). This compound was prepared analogously as  
described for 2, using 1 (160 mg, 0.17 mmol), PiPr3 (160 µL,  
0.80 mmol), and MeOCHdCHC(O)Me (0.35 µL, 0.35 mmol) as  
starting materials. The reaction mixture was stirred for 2 h  
at 80 °C. A white microcrystalline solid was obtained: yield  
197 mg (85%); mp 209 °C. Anal. Calcd for C23H50ClIrO2P2: C,  
42.61; H, 7.77. Found: C, 42.75; H, 7.81. MS (70 eV): m/z (Ir)  
648 (M+, 100), 612 (M+ - HCl, 16), 548 (M+ - MeOCHdCHC-  
(O)Me, 35), 488 (M+ - PiPr3, 34), 100 (MeOCHdCHC(O)Me+,  
1
ν(CdO) 1530 cm-1. H NMR (200 MHz, CDCl3): δ 11.26 (dd,  
J(H,H) ) 2.0 and 7.3 Hz, 1 H, IrCH), 8.83 (ddt, J(H,H) ) 2.0  
and 2.7, J(P,H) ) 2.4 Hz, 1 H, C(O)H), 6.99 (d, J(H,H) ) 7.3  
Hz, 1 H, IrCHdCH), 2.43 (m, 6 H, PCHCH3), 1.26, 1.12 (both  
dvt, N ) 13.5, J(H,H) ) 7.0 Hz, 18 H each, PCHCH3), -23.19  
(dt, J(H,H) ) 2.7, J(P,H) ) 15.8 Hz, 1 H, IrH). 13C NMR (50.3  
MHz, CDCl3): δ 206.6 (t, J(P,C) ) 6.1 Hz, IrCH), 197.7 (s,  
CdO), 133.1 (s, IrCHdCH), 24.5 (vt, N ) 27.5 Hz, PCHCH3),  
19.1, 18.9 (both s, PCHCH3). 31P NMR (36.3 MHz, C6D6): δ  
20.0 (s, d in off-resonance).  
1
46). IR (KBr): ν(IrH) 2275, ν(CdO) 1525 cm-1. H NMR (200  
MHz, CDCl3): δ 4.22 (s, 1 H, IrCHdCH), 3.65 (s, 3 H, OCH3),  
(23) Leigh, G. J.; Richards, R. L. In Comprehensive Organometallic  
Chemistry; Wilkinson, G., Stone, F. G. A., Abel, E. W., Eds.; Perga-  
mon: New York, 1982; Vol. 5, Chapter 36.2.  
Preparation of [IrH(Cl){κ2(C,O)-CHdC(Me)CHdO}-  
(PiPr3)2] (7). This compound was prepared analogously as  
described for 2, using 1 (120 mg, 0.13 mmol), PiPr3 (120 µL,  
0.60 mmol), and methacrolein (22 µL, 0.26 mmol) as starting  
materials. The reaction mixture was stirred for 2 h at 80 °C.  
(24) van der Ent, A.; Onderdelinden, A. L. Inorg. Synth. 1973, 14,  
92-95.  
(25) Collman, J. P.; Kang, J. W. J. Am. Chem. Soc. 1967, 89, 844-  
851.  
(26) Fild, M.; Stelzer, O.; Schmutzler, R. Inorg. Synth. 1973, 14, 4-9.  
Hydrido(vinyl)iridium(III) Complexes  
Organometallics, Vol. 24, No. 21, 2005 5135  
An orange microcrystalline solid was obtained: yield 137 mg  
(83%); mp 167 °C dec. Anal. Calcd for C22H48ClIrOP2: C, 42.74;  
H, 7.83. Found: C, 42.94; H, 8.01. MS (70 eV): m/z (Ir) 618  
(M+, 22), 548 (M+ - CH2dC(Me)C(O)H, 28), 458 (M+ - PiPr3,  
12), 70 (CH2dC(Me)C(O)H+, 100). IR (KBr): ν(IrH) 2275,  
exactly located. 31P NMR (36.3 MHz, CDCl3): δ 18.0 (s, d in  
off-resonance).  
Preparation of [IrH(Cl){κ2(C,O)-CHdCHC(NMe2)dO}-  
(PiPr3)2] (11). A suspension of 1 (200 mg, 0.22 mmol) in  
benzene (5 mL) was treated under continuous stirring first  
with PiPr3 (200 µL, 1.00 mmol) and then with CH2dCHC(O)-  
NMe2 (45 µL, 0.44 mmol) at room temperature. After the  
reaction mixture was stirred for 17 days in the dark, a color-  
less solution was obtained. The solvent was evaporated in  
vacuo, and the remaining white microcrystalline solid was  
washed three times with 5 mL portions of hexane (0 °C) and  
dried: yield 228 mg (79%); mp 206 °C dec. Anal. Calcd for  
C23H51ClIrNOP2: C, 42.68; H, 7.94; N, 2.16. Found: C, 42.81;  
ν(CdO) 1555 cm-1 1H NMR (200 MHz, C6D6): δ 10.76 (d,  
.
J(H,H) ) 2.0 Hz, 1 H, IrCH), 8.56 (ddt, J(H,H) ) 2.0 and 2.7,  
J(P,H) ) 2.4 Hz, 1 H, C(O)H), 2.43 (m, 6 H, PCHCH3), 1.77 (s,  
3 H, IrCHdCCH3), 1.18, 1.16 (both dvt, N ) 13.2, J(H,H) )  
7.3 Hz, 18 H each, PCHCH3), -23.44 (dt, J(H,H) ) 2.7, J(P,H)  
) 16.0 Hz, 1 H, IrH). 13C NMR (50.3 MHz, CDCl3): δ 198.5 (s,  
CdO), 198.3 (t, J(P,C) ) 6.1 Hz, IrCH), 138.8 (s, IrCHdCH),  
24.1 (vt, N ) 27.4 Hz, PCHCH3), 19.2, 19.1 (both s, PCHCH3),  
15.8 (s, dCCH3). 31P NMR (36.3 MHz, C6D6): δ 20.9 (s, d in  
off-resonance).  
H, 8.14; N, 2.10. MS (70 eV): m/z (Ir) 647 (M+, 18), 548 (M+  
CH2dCHC(O)NMe2, 20), 487 (M+ - PiPr3, 18), 99 (CH2dCHC-  
(O)NMe2+, 100). IR (KBr): ν(IrH) 2230, ν(CdO) 1570 cm-1  
-
Preparation of [IrH(Cl){κ2(C,O)-CHdC(iPr)CHdO}-  
(PiPr3)2] (8). This compound was prepared analogously as  
described for 2, using 1 (120 mg, 0.13 mmol), PiPr3 (120 µL,  
0.60 mmol), and CH2dC(iPr)C(O)H (26 µL, 0.26 mmol) as  
starting materials. The reaction mixture was stirred for 2 h  
at 80 °C. An orange microcrystalline solid was obtained: yield  
147 mg (85%); mp 170 °C dec. Anal. Calcd for C24H52ClIrOP2:  
C, 44.60; H, 8.11. Found: C, 44.39; H, 8.41. MS (70 eV): m/z  
(Ir) 646 (M+, 42), 548 (M+ - CH2dC(iPr)C(O)H, 71), 486 (M+  
- PiPr3, 17), 98 (CH2dC(iPr)C(O)H+, 100). IR (KBr): ν(IrH)  
.
1H NMR (90 MHz, CDCl3): δ 9.88 (d, J(H,H) ) 7.9 Hz, 1 H,  
IrCH), 6.48 (d, J(H,H) ) 7.9 Hz, 1 H, IrCHdCH), 3.10, 3.04  
(both s, 3 H each, NCH3), 2.52 (m, 6 H, PCHCH3), 1.31, 1.13  
(both dvt, N ) 13.4, J(H,H) ) 7.3 Hz, 18 H each, PCHCH3),  
-25.16 (t, J(P,H) ) 15.6 Hz, 1 H, IrH]. 31P NMR (36.3 MHz,  
CDCl3): δ 18.8 (s, d in off-resonance).  
Preparation of [IrH(Cl){κ2(C,O)-CHdC(Me)C(NH2)d  
O}(PiPr3)2] (12). This compound was prepared analogously  
as described for 10, using 1 (100 mg, 0.11 mmol), PiPr3 (100  
µL, 0.50 mmol), and CH2dC(Me)C(O)NH2 (19 mg, 0.22 mmol)  
as starting materials. A white microcrystalline solid was  
obtained: yield 126 mg (89%); mp 174 °C dec. Anal. Calcd for  
C22H49ClIrNOP2: C, 41.73; H, 7.80; N, 2.21. Found: C, 42.08;  
1
2240, ν(CdO) 1550 cm-1. H NMR (200 MHz, C6D6): δ 10.85  
(d, J(H,H) ) 2.5 Hz, 1 H, IrCH), 8.68 (ddt, J(H,H) ) 2.5 and  
2.7, J(P,H) ) 2.4 Hz, 1 H, C(O)H), 2.48 (m, 6 H, PCHCH3),  
1.29, 1.12 (both dvt, N ) 13.5, J(H,H) ) 7.0 Hz, 18 H each,  
PCHCH3), 1.00 (d, J(H,H) ) 7.0 Hz, 6 H, CCHCH3), -23.38  
(dt, J(H,H) ) 2.7, J(P,H) ) 16.2 Hz, 1 H, IrH), signal of CHCH3  
probably covered by signal of PCHCH3 protons. 31P NMR (36.3  
MHz, C6D6): δ 19.7 (s, d in off-resonance).  
H, 8.10; N, 2.13. MS (70 eV): m/z (Ir) 633 (M+, 9), 597 (M+  
-
HCl, 1), 548 (M+ - CH2dC(Me)C(O)NH2, 10), 85 (CH2dC-  
(Me)C(O)NH2+, 100). IR (KBr): ν(NH) 3300, 3195, ν(IrH) 2250,  
ν(CdO) 1560 cm-1. 1H NMR (90 MHz, CDCl3): δ 9.18 (br s, 1  
H, IrCH), 2.42 (m, 6 H, PCHCH3), 1.63 (br s, 3 H, dCCH3),  
1.26, 1.15 (both dvt, N ) 13.2, J(H,H) ) 7.1 Hz, 18 H each,  
PCHCH3), -25.46 (t, J(P,H) ) 15.9 Hz, 1 H, IrH), signal of  
NH2 protons not exactly located. 31P NMR (36.3 MHz,  
CDCl3): δ 17.9 (s, d in off-resonance).  
Preparation of [IrH(Cl){κ2(C,O)-CHdC(Me)C(OMe)d  
O}(PiPr3)2] (9). This compound was prepared analogously as  
described for 2, using 1 (120 mg, 0.13 mmol), PiPr3 (120 µL,  
0.60 mmol), and CH2dC(Me)CO2Me (28 µL, 0.26 mmol) as  
starting materials. The reaction mixture was stirred for 3 h  
at 80 °C. A white microcrystalline solid was obtained: yield  
149 mg (86%); mp 192 °C dec. Anal. Calcd for C23H50ClIrO2P2:  
C, 42.61; H, 7.77. Found: C, 42.20; H, 7.55. MS (70 eV): m/z  
(Ir) 648 (M+, 17), 548 (M+ - CH2dC(Me)CO2Me, 47), 488 (M+  
- PiPr3, 9), 100 (CH2dC(Me)CO2Me+, 100). IR (KBr): ν(IrH)  
Preparation of [IrH(Cl){κ2(C,O)-C(Ph)dCHC(NH2)dO}-  
(PiPr3)2] (13). A suspension of 1 (160 mg, 0.18 mmol) in  
benzene (5 mL) was treated under continuous stirring first  
with PiPr3 (160 µL, 0.80 mmol) and then with cinnamic acid  
amide (60 mg, 0.36 mmol) at room temperature. After the  
reaction mixture was stirred for 3 h at 80 °C, a yellow solution  
was obtained. The solution was concentrated in vacuo to ca. 3  
mL and stored for 6 h. A yellow microcrystalline solid  
precipitated, which was recrystallized from CH2Cl2/hexane (1:  
5, 6 mL): yield 186 mg (75%); mp 201 °C dec. Anal. Calcd for  
C27H51ClIrNOP2: C, 46.64; H, 7.39; N, 2.01. Found: C, 46.83;  
1
2260, ν(CdO) 1590 cm-1. H NMR (200 MHz, CDCl3): δ 9.67  
(s, 1 H, IrCH), 3.88 (s, 3 H, OCH3), 2.46 (m, 6 H, PCHCH3),  
1.80 (s, 3 H, IrCHdCCH3), 1.25, 1.11 (both dvt, N ) 13.3,  
J(H,H) ) 7.0 Hz, 18 H each, PCHCH3), -26.45 (t, J(P,H) )  
15.3 Hz, 1 H, IrH). 13C NMR (50.3 MHz, CDCl3): δ 180.8 (s,  
CdO), 174.8 (t, J(P,C) ) 7.7 Hz, IrCH), 123.9 (s, IrCHdC),  
52.9 (s, OCH3), 24.1 (vt, N ) 26.4 Hz, PCHCH3), 19.1, 18.8  
(both s, PCHCH3). 31P NMR (36.3 MHz, C6D6): δ 18.8 (s, d in  
off-resonance).  
Preparation of [IrH(Cl){κ2(C,O)-CHdCHC(NH2)dO}-  
(PiPr3)2] (10). A suspension of 1 (150 mg, 0.16 mmol) in  
benzene (5 mL) was treated under continuous stirring first  
with PiPr3 (160 µL, 0.80 mmol) and then with acrylic acid  
amide (24 mg, 0.32 mmol) at room temperature. After the  
reaction mixture was irradiated for 1 h in an ultrasonic bath,  
a colorless solution was obtained. The solution was concen-  
trated in vacuo to ca. 3 mL and stored for 6 h. A white  
microcrystalline solid precipitated, which was recrystallized  
from CH2Cl2/hexane (1:5, 6 mL): yield 185 mg (89%); mp 235  
°C dec. Anal. Calcd for C21H47ClIrNOP2: C, 40.73; H, 7.65; N,  
2.26. Found: C, 41.08; H, 7.63; N, 2.35. MS (70 eV): m/z (Ir)  
619 (M+, 7), 548 (M+ - CH2dCHC(O)NH2, 9), 459 (M+ - PiPr3,  
9), 71 (CH2dCHC(O)NH2+, 100). IR (KBr): ν(NH) 3340, 3210,  
ν(IrH) 2275, ν(CdO) 1555 cm-1. 1H NMR (90 MHz, CDCl3): δ  
9.87 (d, J(H,H) ) 7.3 Hz, 1 H, IrCH), 6.22 (d, J(H,H) ) 7.3  
Hz, 1 H, IrCHdCH), 2.51 (m, 6 H, PCHCH3), 1.29, 1.17 (both  
dvt, N ) 13.2, J(H,H) ) 7.3 Hz, 18 H each, PCHCH3), -25.74  
(t, J(P,H) ) 16.1 Hz, 1 H, IrH), signal of NH2 protons not  
H, 7.23; N, 2.21. MS (70 eV): m/z (Ir) 695 (M+, 10), 548 (M+  
-
PhCHdCHC(O)NH2, 20), 147 (PhCHdCHC(O)NH2+, 100). IR  
(KBr): ν(NH) 3370, 3190, ν(IrH) 2260, ν(CdO) 1565 cm-1. 1H  
NMR (200 MHz, CDCl3): δ 7.68, 7.21 (both m, 5 H, C6H5), 6.73  
(t, J(P,H) ) 1.3 Hz, 1 H, IrC(Ph)dCH), 2.50 (m, 6 H, PCHCH3),  
1.17, 1.14 (both dvt, N ) 13.3, J(H,H) ) 7.1 Hz, 18 H each,  
PCHCH3), -26.05 (t, J(P,H) ) 16.5 Hz, 1 H, IrH), signal of  
NH2 protons not exactly located. 31P NMR (36.3 MHz,  
CD2Cl2): δ 6.9 (s, d in off-resonance).  
Reaction of the Starting Materials 1 and PiPr3 with  
RCHdCHC(O)H (R ) Me, Ph). A suspension of 1 (80 mg,  
0.09 mmol) in toluene (5 mL) was treated under continuous  
stirring first with PiPr3 (80 µL, 0.40 mmol) and then with  
crotonaldehyde (15 µL, 0.18 mmol) or cinnamic aldehyde (23  
µL, 0.18 mmol), respectively. Since at room temperature no  
reaction occurred, the solution was stirred for 2 h at 80 °C. A  
pale yellow solution was obtained, which, after it was cooled  
to 20 °C, was evaporated in vacuo. The 1H and 31P NMR  
spectra revealed that the residue contained, besides traces of  
undefined compounds, the carbonyl complex trans-[IrCl(CO)-  
5136 Organometallics, Vol. 24, No. 21, 2005  
Dirnberger and Werner  
(PiPr3)2] (14) as the main component. It was identified by  
comparison of the NMR data with those of an authentic  
sample.27  
gously as described for 17, a yellow microcrystalline solid was  
obtained: yield 96 mg (80%); mp 175 °C dec. Anal. Calcd for  
C24H50ClIrO4P2: C, 41.64; H, 7.28. Found: C, 41.20; H, 7.20.  
MS (70 eV): m/z (Ir) 692 (M+, 45), 656 (M+ - HCl, 3), 548 (M+  
- CHCO2MedCHCO2Me, 100), 532 (M+ - PiPr3, 14), 144  
(CHCO2MedCHCO2Me+, 16). IR (KBr): ν(IrH) 2305, ν(Cd  
Preparation of trans-[IrCl(η2-CH2dCHCO2Me)(PiPr3)2]  
(15). A suspension of 1 (150 mg, 0.16 mmol) in toluene (5 mL)  
was treated under continuous stirring first with PiPr3 (160  
µL, 0.80 mmol) and then with methyl acrylate (29 µL, 0.32  
mmol). After the reaction mixture was stirred for 5 min at  
room temperature, a red solution was obtained. The solvent  
was evaporated in vacuo, the residue was dissolved in pentane  
(3 mL), and the solution was stored for 12 h at -78 °C. A red  
microcrystalline solid precipitated, which was separated from  
the mother liquor, washed twice with small amounts of hexane  
(0 °C), and dried: yield 168 mg (79%); mp 110 °C dec. Anal.  
Calcd for C22H48ClIrO2P2: C, 41.66; H, 7.63. Found: C, 41.57;  
H, 7.71. MS (70 eV): m/z (Ir) 548 (M+ - CH2dCHCO2Me, 8),  
O)uncoord 1710, ν(CdO)coord 1590 cm-1 1H NMR (200 MHz,  
.
CDCl3): δ 6.72 (t, J(P,H) ) 1.3 Hz, 1 H, IrCdCH), 3.82, 3.57  
(both s, 3 H each, OCH3), 2.59 (m, 6 H, PCHCH3), 1.18, 1.03  
(both dvt, N ) 13.5, J(H,H) ) 7.0 Hz, 18 H each, PCHCH3),  
-27.86 (t, J(P,H) ) 15.1 Hz, 1 H, IrH). 13C NMR (50.3 MHz,  
CDCl3): δ 182.1, 176.4 (both s, CdO), 178.9 (t, J(P,C) ) 6.8  
Hz, IrC), 122.3 (s, IrCdCH), 53.0, 51.2 (both s, OCH3), 24.5  
[vt, N ) 27.0 Hz, PCHCH3), 19.7, 18.8 (both s, PCHCH3). 31P  
NMR (36.3 MHz, C6D6): δ 18.6 (s, d in off-resonance).  
Preparation of [IrH(Cl){κ2(C,O)-C(Ph)dCHC(Ph)dO}-  
(PiPr3)2] (19) and [IrH(Cl){κ2(C,O)-C6H4C(CHdCHPh)d  
O}(PiPr3)2] (20). A suspension of 1 (200 mg, 0.22 mmol) in  
toluene (5 mL) was treated under continuous stirring first with  
PiPr3 (200 µL, 1.00 mmol) and then with PhCHdCHC(O)Ph  
(23 µL, 0.26 mmol). After the reaction mixture was stirred for  
2 h at 80 °C, a red solution was obtained. The solution was  
cooled to room temperature and brought to dryness in vacuo.  
The oily residue was dissolved in benzene/hexane (6 mL; 1:2),  
and the solution was chromatographed on Al2O3 (neutral,  
activity grade V, length of column 8 cm). With benzene/hexane  
(1:2) an orange fraction was eluted, from which after removal  
of the solvent compound 19 was obtained. Subsequent elution  
with benzene/diethyl ether (1:1) afforded a red fraction, from  
which the solvent was evaporated in vacuo. The red micro-  
crystalline solid analyzed as 20 was washed twice with small  
amounts of hexane (0 °C) and dried: yield 152 mg (45%) of 19  
and 136 mg (40%) of 20. Data for 19: mp 181 °C dec. Anal.  
Calcd for C33H54ClIrOP2: C, 52.40; H, 7.20. Found: C, 52.22;  
H, 7.32. MS (70 eV): m/z (Ir) 756 (M+, 1), 548 (M+ - PhCHd  
CHC(O)Ph, 6), 208 (PhCHdCHC(O)Ph+, 100). IR (KBr):  
1
86 (CH2dCHCO2Me+, 100). IR (KBr): ν(CdO) 1760 cm-1. H  
NMR (200 MHz, C6D6): δ 3.58 (m, 1 H, dCHCO2Me), 3.42 (s,  
3 H, OCH3), 3.10, 2.44 (both m, 3 H each, PCHCH3), 2.54, 1.77  
(both m, 1 H each, dCH2), 1.29 (m, 36 H, PCHCH3). 31P NMR  
(162.0 MHz, C6D6): δ 15.8, 13.8 (AB spin system, J(P,P) )  
365 Hz).  
Preparation  
of  
trans-[IrCl{η2-(E)-CHCO2Med  
CHCO2Me}(PiPr3)2] (16). This compound was prepared  
analogously as described for 15, using 1 (150 mg, 0.16  
mmol), PiPr3 (160 µL, 0.80 mmol), and either dimethyl  
fumarate (46 mg, 0.32 mmol) or dimethyl maleate (41 µL, 0.32  
mmol) as starting material. A red microcrystalline solid was  
obtained: yield 174 mg (75%); mp 120 °C dec. Anal. Calcd for  
C24H50ClIrO4P2: C, 41.64; H, 7.28. Found: C, 41.71; H, 7.99.  
MS (70 eV): m/z (Ir) 548 (M+ - CHCO2MedCHCO2Me), 10),  
144 (CHCO2MedCHCO2Me+, 100). IR (KBr): ν(CdO) 1705  
cm-1. 1H NMR (200 MHz, CDCl3): δ 3.82 (t, J(P,H) ) 6.3 Hz,  
2 H, dCH), 3.45 (s, 6 H, OCH3), 2.81 (m, 6 H, PCHCH3), 1.33  
(dvt, N ) 12.8, J(H,H) ) 6.6 Hz, 18 H, PCHCH3), 1.19 (dvt, N  
) 13.9, J(H,H) ) 7.0 Hz, 18 H, PCHCH3). 13C NMR (50.3 MHz,  
CDCl3): δ 174.0 (s, CdO), 51.4 (s, OCH3), 22.6 (vt, N ) 24.2  
Hz, PCHCH3), 20.2, 19.6 (both s, PCHCH3), 19.5 (br s, dCH).  
31P NMR (36.3 MHz, C6D6): δ 9.8 (s).  
1
ν(IrH) 2255, ν(CdO) 1545 cm-1. H NMR (200 MHz, CDCl3):  
δ 8.10, 7.36 (both m, 10 H, C6H5), 2.48 (m, 6 H, PCHCH3),  
1.16, 1.03 (both dvt, N ) 13.4, J(H,H) ) 6.9 Hz, 18 H each,  
PCHCH3), -22.88 (t, J(P,H) ) 16.5 Hz, 1 H, IrH), signal of  
IrC(Ph)dCH proton probably covered by signals of phenyl  
protons. 13C NMR (50.3 MHz, CDCl3): δ 209.4 (t, J(P,C) ) 5.3  
Hz, IrCH), 198.1 (s, CdO), 148.4 (s, IrC(Ph)dCH), 136.7, 131.4,  
130.9, 129.7, 128.5, 127.5, 127.3 (all s, C6H5), 25.1 (vt, N )  
27.3 Hz, PCHCH3), 19.9, 19.3 (both s, PCHCH3). 31P NMR (36.3  
MHz, C6D6): δ 7.6 (s, d in off-resonance). - Data for 20: mp  
230 °C dec. Anal. Calcd for C33H54ClIrOP2: C, 52.40; H, 7.20.  
Found: C, 52.68; H, 7.44. IR (KBr): ν(IrH) 2270, ν(CdO) 1515  
cm-1. 1H NMR (200 MHz, CDCl3): δ 8.07, 7.54 (both br s, 1 H  
each, dCH), 7.47, 6.81 (both m, 10 H, C6H5), 2.25 (m, 6 H,  
PCHCH3), 1.15, 0.87 (both dvt, N ) 13.3, J(H,H) ) 6.9 Hz, 18  
Preparation of [IrH(Cl){κ2(C,O)-CHdCHC(OMe)dO}-  
(PiPr3)2] (17). A solution of 15 (120 mg, 0.19 mmol) in benzene  
(5 mL) was stirred either for 21 days at room temperature or  
for 2 h at 80 °C. A change of color from red to pale yellow  
occurred. The solvent was evaporated in vacuo, the oily residue  
was dissolved in benzene/hexane (1:2, 3 mL), and the solution  
was chromatographed on Al2O3 (neutral, activity grade V,  
length of column 5 cm). With benzene/hexane (1:2) a nearly  
colorless fraction was eluted, which was brought to dryness  
in vacuo. The remaining white microcrystalline solid was  
washed twice with hexane (3 mL) and dried: yield 108 mg  
(90%); mp 167 °C dec. Anal. Calcd for C22H48ClIrO2P2: C,  
41.66; H, 7.63. Found: C, 41.43; H, 7.81. MS (70 eV): m/z (Ir)  
H each, PCHCH3), -23.98 (t, J(P,H) ) 16.1 Hz, 1 H, IrH). 13  
C
634 (M+, 75), 548 (M+ - CH2dCHCO2Me, 100), 474 (M+  
PiPr3, 86), 86 (CH2dCHCO2Me+, 31). IR (KBr): ν(IrH) 2260,  
ν(CdO) 1575 cm-1 1H NMR (200 MHz, CDCl3): δ 10.37 [d,  
-
NMR (50.3 MHz, CDCl3): δ 201.0 (s, CdO), 165.2 (t, J(P,C) )  
6.1 Hz, IrC of C6H4), 118.9, 118.5 (both s, dCH), 145.3, 144.7,  
142.0, 135.1, 133.5, 130.7, 129.9, 128.9, 128.7 (all s, C6H4 and  
C6H5), 23.6 (vt, N ) 26.4 Hz, PCHCH3), 19.4, 18.8 (both s,  
PCHCH3). 31P NMR (36.3 MHz, C6D6): δ 12.7 (s, d in  
off-resonance).  
Preparation of [IrH(Cl){κ2(C,O)-CHdCHC(OH)dO}-  
(PiPr3)2] (21) and [IrH(Cl)(κ2(O,O)-O2CCHdCH2)(PiPr3)2]  
(22). A suspension of 1 (200 mg, 0.22 mmol) in toluene (5 mL)  
was treated under continuous stirring first with PiPr3 (200  
µL, 1.00 mmol) and then with acrylic acid (30 µL, 0.44 mmol).  
After the reaction mixture was stirred for 10 min at room  
temperature, a yellow solution was obtained. The solvent was  
evaporated in vacuo, the oily residue was dissolved in hexane  
(3 mL), and the solution was stored for 12 h at -78 °C. White  
crystals of 21 precipitated, which were separated from the  
mother liquor, washed twice with small amounts of hexane (0  
°C), and dried. The mother liquor was brought to dryness in  
vacuo to give 22 as a yellow oil, which was characterized by  
.
J(H,H) ) 7.8 Hz, 1 H, IrCH), 6.38 (d, J(H,H) ) 7.8 Hz, 1 H,  
IrCHdCH), 3.89 (s, 3 H, OCH3), 2.53 (m, 6 H, PCHCH3), 1.30,  
1.15 (both dvt, N ) 13.3, J(H,H) ) 6.8 Hz, 18 H each,  
PCHCH3), -26.70 (t, J(P,H) ) 15.1 Hz, 1 H, IrH). 13C NMR  
(50.3 MHz, CDCl3): δ 183.7 (t, J(P,C) ) 7.0 Hz, IrCH), 182.0  
(s, CdO), 118.6 (s, IrCH)CH), 52.7 (s, OCH3), 24.1 (vt, N )  
26.6 Hz, PCHCH3), 19.1, 19.0 (both s, PCHCH3). 31P NMR (36.3  
MHz, C6D6): δ 18.6 (s, d in off-resonance).  
Preparation of [IrH(Cl){κ2(C,O)-C(CO2Me)dCHC(OMe)d  
O}(PiPr3)2] (18). A solution of 16 (120 mg, 0.18 mmol) in  
benzene (5 mL) was irradiated for 12 h with a UV lamp  
(Hanovia 450 W). After the solution was worked up analo-  
(27) (a) Strohmeier, W.; Onoda, T. Z. Naturforsch., B 1968, 23,  
1377-1379. (b) Werner, H.; Ho¨hn, A. Z. Naturforsch., B 1984, 39,  
1505-1509.  
Hydrido(vinyl)iridium(III) Complexes  
Organometallics, Vol. 24, No. 21, 2005 5137  
NMR data. Yield: 127 mg (46%) of 21 and ca. 45% of 22. Data  
for 21: mp 127 °C dec. Anal. Calcd for C21H46ClIrO2P2: C,  
40.67; H, 7.48. Found: C, 41.61; H, 7.53. MS (70 eV): m/z (Ir)  
548 (M+ - CH2dCHCO2H, 6), 72 (CH2dCHCO2H+, 100). IR  
with LiAlH4 (25 mg, 0.65 mmol) and stirred for 12 h at room  
temperature. The solvent was evaporated in vacuo, and the  
residue was extracted three times with pentane (15 mL each).  
The combined extracts were brought to dryness in vacuo to  
give a white microcrystalline solid, which was identified as  
[IrH5(PiPr3)2] (25) by comparison of the NMR data with those  
of an authentic sample.19 The same result was obtained if a  
solution of 2 in methanol was treated with either NaBH4 or  
LiHBEt3.  
(KBr): ν(OH) 3435, ν(IrH) 2250 cm-1 1H NMR (90 MHz,  
.
C6D6): δ 9.72 (d, J(H,H) ) 7.3 Hz, 1 H, IrCH), 6.87 (d, J(H,H)  
) 7.3 Hz, 1 H, IrCHdCH), 2.75 (m, 6 H, PCHCH3), 1.39 (m,  
36 H, PCHCH3), -25.23 (t, J(P,H) ) 16.1 Hz, 1 H, IrH), signal  
of OH proton not exactly located. 31P NMR (36.3 MHz, C6D6):  
δ 17.0 (s, d in off-resonance). Data for 22: IR (KBr): ν(IrH)  
2285, ν(OCO) 1510 cm-1. 1H NMR (90 MHz, C6D6): δ 6.12 (dd,  
J(H,H) ) 17.4 and 2.4 Hz, 1 H, one H of dCH2), 5.71 (dd,  
J(H,H) ) 17.4 and 10.0 Hz, 1 H, CHdCH2), 5.10 (dd, J(H,H)  
) 10.0 and 2.4 Hz, 1 H, one H of dCH2), 2.60 (m, 6 H,  
PCHCH3), 1.33, 1.28 (both dvt, N ) 13.2, J(H,H) ) 7.2 Hz, 18  
Preparation of [IrCl2{κ2(C,O)-CHdC(Cl)C(Me)dO}-  
(PiPr3)2] (27). A solution of 2 (95 mg, 0.15 mmol) in chloroform  
(5 mL) was treated dropwise with a saturated solution of Cl2  
in chloroform (ca. 0.5 mL) at room temperature. A quick  
change of color from yellow to deep red occurred. After the  
solution was stirred for 3 min, it was treated with an excess  
of the solution of Cl2 in chloroform (1 mL) and continuously  
stirred for 5 min. The solvent was evaporated in vacuo, and  
the remaining red microcrystalline solid was washed three  
times with small amounts of pentane (0 °C) and dried: yield  
95 mg (90%); mp 191 °C dec. Anal. Calcd for C22H46Cl3IrOP2:  
C, 38.46; H, 6.75. Found: C, 38.90; H, 6.90. MS (70 eV): m/z  
(Ir) 687 (M+, 10), 651 (M+ - HCl, 5), 527 (M+ - PiPr3, 100). IR  
(KBr): ν(CdO) 1505 cm-1. 1H NMR (200 MHz, CDCl3): δ 12.35  
(s, 1 H, IrCH), 2.52 (m, 6 H, PCHCH3), 2.47 (t, J(P,H) ) 1.6  
Hz, 3 H, C(O)CH3), 1.25, 1.16 (both dvt, N ) 13.5, J(H,H) )  
7.1 Hz, 18 H each, PCHCH3). 13C NMR (50.3 MHz, CDCl3): δ  
209.0 (s, CdO), 198.7 (t, J(P,C) ) 5.1 Hz, IrCH), 127.3 (s,  
IrCHdC), 22.7 (s, C(O)CH3), 21.4 (vt, N ) 24,5 Hz, PCHCH3),  
19.6, 19.5 (both s, PCHCH3). 31P NMR (36.3 MHz, CDCl3): δ  
-9.4 (s).  
H each, PCHCH3), -34.80 (t, J(P,H) ) 12.2 Hz, 1 H, IrH). 31  
NMR (36.3 MHz, C6D6): δ 19.6 (s, d in off-resonance).  
P
Preparation of [IrH(Cl)(κ2(O,O)-O2CCHdCHMe)(PiPr3)2]  
(23). A suspension of 1 (100 mg, 0.11 mmol) in toluene (5 mL)  
was treated under continuous stirring first with PiPr3 (100  
µL, 0.50 mmol) and then with crotonic acid (19 µL, 0.22 mmol).  
After the reaction mixture was stirred for 10 min at room  
temperature, a yellow solution was obtained. The solvent was  
evaporated in vacuo, the oily residue was dissolved in hexane  
(3 mL), and the solution was stored for 12 h at -78 °C. A pale  
yellow microcrystalline solid precipitated, which was separated  
from the mother liquor, washed twice with small amounts of  
hexane (0 °C), and dried: yield 99 mg (70%); mp 96 °C dec.  
Anal. Calcd for C22H48ClIrO2P2: C, 41.66; H, 7.63. Found: C,  
41.93; H, 7.59. MS (70 eV): m/z (Ir) 634 (M+, 19), 598 (M+  
-
HCl, 3), 548 (M+ - MeCHdCHCO2H, 90), 474 (M+ - PiPr3,  
27), 86 (MeCHdCHCO2H+, 100). IR (KBr): ν(IrH) 2260,  
Preparation of [IrCl2{κ2(C,O)-CHdC(Cl)CHdO}(PiPr3)2]  
(28). This compound was prepared analogously as described  
for 27, using 6 (80 mg, 0.14 mmol) and a saturated solution of  
Cl2 in chloroform as starting materials. A red microcrystalline  
solid was obtained: yield 78 mg (87%); mp 176 °C dec. Anal.  
Calcd for C21H44Cl3IrOP2: C, 37.47; H, 6.59. Found: C, 37.79;  
H, 6.84. MS (70 eV): m/z (Ir) 673 (M+, 2), 637 (M+ - HCl, 6),  
513 (M+ - PiPr3, 100). IR (KBr): ν(CdO) 1520 cm-1. 1H NMR  
(200 MHz, CDCl3): δ 12.70 (d, J(H,H) ) 3.0 Hz, 1 H, IrCH),  
8.14 (dt, J(H,H) ) 3.0, J(P,H) ) 1.8 Hz, 1 H, C(O)H), 2.57 (m,  
6 H, PCHCH3), 1.31, 1.19 (both dvt, N ) 13.7, J(H,H) ) 7.1  
Hz, 18 H each, PCHCH3). 13C NMR (50.3 MHz, CDCl3): δ 206.5  
(t, J(P,C) ) 5.2 Hz, IrCH), 199.2 (s, CdO), 130.4 (s, IrCHd  
CH), 21.5 (vt, N ) 24.2 Hz, PCHCH3), 19.8, 19.6 (both s,  
PCHCH3). 31P NMR (36.3 MHz, CDCl3): δ -10.1 (s).  
ν(OCO) 1520 cm-1 1H NMR (200 MHz, C6D6): δ 6.74 (dq,  
.
J(H,H) ) 15.5 and 6.9 Hz, 1 H, dCHCH3), 5.56 (dq, J(H,H) )  
15.5 and 1.5 Hz, 1 H, CHdCHCH3), 2.64 (m, 6 H, PCHCH3),  
1.37, 1.33 (both dvt, N ) 13.3, J(H,H) ) 7.0 Hz, 18 H each,  
PCHCH3), -34.46 (t, J(P,H) ) 12.4 Hz, 1 H, IrH), signal of  
dCHCH3 protons probably covered by signals of PCHCH3  
protons. 31P NMR (36.3 MHz, C6D6): δ 19.6 (s, d in off-  
resonance).  
Reaction of the Starting Materials 1 and PiPr3 with  
RCHdCHCO2Me (R ) Me, Ph). A suspension of 1 (100 mg,  
0.11 mmol) in toluene (5 mL) was treated under continuous  
stirring first with PiPr3 (100 µL, 0.50 mmol) and then with  
methyl crotonate (24 µL, 0.22 mmol) or methyl cinnamate (36  
mg, 0.22 mmol), respectively. After the reaction mixture was  
stirred for 24 h at room temperature or irradiated for 2 h with  
a UV lamp (Hanovia 450 W), a brownish solution was obtained.  
The solvent was evaporated in vacuo and the yellow-brown  
residue dried. The 1H and 31P NMR spectra revealed that,  
besides traces of undefined compounds the residue contained  
the dihydrido complex [IrH2(Cl)(PiPr3)2] (24) as the main  
component. It was identified by comparison of the NMR data  
with those of an authentic sample.13,28 The same result was  
obtained if a 5-fold excess of the corresponding ester was used  
as the substrate.  
Preparation of [IrH(I){κ2(C,O)-CHdCHC(Me)dO}-  
(PiPr3)2] (29). A solution of 2 (130 mg, 0.21 mmol) in acetone  
(10 mL) was treated with NaI (150 mg, 1.00 mmol) and stirred  
for 7 days at room temperature. The solvent was evaporated  
in vacuo, the residue was extracted with benzene (20 mL), and  
the extract was brought to dryness in vacuo. A yellow micro-  
crystalline solid was obtained, which was washed twice with  
small amounts of pentane and dried: yield 119 mg (80%); mp  
138 °C dec. Anal. Calcd for C22H48IIrOP2: C, 37.23; H, 6.82.  
Found: C, 37.63; H, 6.75. MS (70 eV): m/z (Ir) 710 (M+, 75),  
640 (M+ - CH2dCHC(O)Me, 100), 70 (CH2dCHC(O)Me+, 60).  
IR (KBr): ν(IrH) 2245, ν(CdO) 1555 cm-1. 1H NMR (200 MHz,  
CDCl3): δ 10.41 (d, J(H,H) ) 7.3 Hz, 1 H, IrCH), 6.64 (d,  
J(H,H) ) 7.3 Hz, 1 H, IrCHdCH), 2.50 (m, 6 H, PCHCH3),  
2.22 (t, J(P,H) ) 1.3 Hz, 3 H, C(O)CH3), 1.21, 1.00 (both dvt,  
N ) 13.5, J(H,H) ) 7.0 Hz, 18 H each, PCHCH3), -24.03 (t,  
J(P,H) ) 15.9 Hz, 1 H, IrH). 13C NMR (50.3 MHz, CDCl3): δ  
209.7 (s, CdO), 198.9 (t, J(P,C) ) 6.7 Hz, IrCH), 133.2 (s,  
IrCHdCH), 26.7 (vt, N ) 28.1 Hz, PCHCH3), 25.0 (s, C(O)-  
CH3), 19.8, 19.3 (both s, PCHCH3). 31P NMR (36.3 MHz,  
C6D6): δ 11.0 (s, d in off-resonance).  
Reaction of Compound 2 with Hydrogen and Pal-  
ladium Catalyst. A solution of 2 (140 mg, 0.22 mmol) in  
benzene (5 mL) was stirred in the presence of palladium on  
charcoal under a dihydrogen atmosphere for 45 min at 40 °C.  
1
The solution was filtered and the filtrate investigated by H  
NMR spectroscopy. Both 24 and ethyl methyl ketone were  
identified by comparison with data reported in the litera-  
ture.13,28,29  
Reaction of Compound 2 with Hydride Donors. A  
solution of 2 (80 mg, 0.13 mmol) in THF (5 mL) was treated  
Preparation of [IrH{κ1-OC(O)Me}{κ2(C,O)-CHdCHC-  
(Me)dO}(PiPr3)2] (30). A solution of 2 (105 mg, 0.17 mmol)  
in acetone (10 mL) was treated with silver acetate (29 mg, 0.17  
mmol) and stirred for 1 h at room temperature. The solvent  
was evaporated in vacuo, the residue was extracted with  
(28) Hietkamp, S.; Stufkens, D. J.; Vrieze, K. J. Organomet. Chem.  
1978, 152, 347-357.  
(29) Hesse, M.; Meier, H.; Zeeh, B. Spektroskopische Methoden in  
der organischen Chemie, 2nd ed.; Thieme Verlag: Stuttgart, New York,  
1984.  
5138 Organometallics, Vol. 24, No. 21, 2005  
Dirnberger and Werner  
benzene (15 mL), and the extract was brought to dryness in  
vacuo. A yellow microcrystalline solid was obtained, which was  
washed twice with small amounts of pentane and dried: yield  
93 mg (85%); mp 106 °C. Anal. Calcd for C24H51IrO3P2: C,  
44.84; H, 8.56. Found: C, 45.07; H, 8.52. IR (KBr): ν(IrH)  
mixture was filtered through a column (length 3 cm) of Al2O3  
(neutral, activity grade V). The aluminum oxide was washed  
three times with 2 mL portions of CH2Cl2, and the filtrate was  
brought to dryness in vacuo. The residue was recrystal-  
lized from CH2Cl2/hexane (1:10) to give white, air-stable  
crystals: yield 195 mg (89%); mp 203 °C dec. Anal. Calcd for  
C23H48F6IrO2P3: C, 36.55; H, 6.40. Found: C, 36.45; H, 6.33.  
ΛM: 79.6 Ω-1 cm2 mol-1. IR (KBr): ν(IrH) 2295, ν(CO) 2050,  
1
2265, ν(OCO) 1625, ν(CdO) 1540 cm-1. H NMR (200 MHz,  
CDCl3): δ 11.00 (d, J(H,H) ) 7.5 Hz, 1 H, IrCH), 6.90 (d,  
J(H,H) ) 7.5 Hz, 1 H, IrCHdCH), 2.36 (t, J(P,H) ) 1.3 Hz, 3  
H, C(O)CH3), 2.10 (m, 6 H, PCHCH3), 1.89 (s, 3 H, O2CCH3),  
1.15, 1.09 (both dvt, N ) 13.2, J(H,H) ) 7.0 Hz, 18 H each,  
PCHCH3), -23.64 (t, J(P,H) ) 16.4 Hz, 1 H, IrH). 13C NMR  
(50.3 MHz, CDCl3): δ 206.8 (s, CdO), 201.7 (t, J(P,C) ) 6.2  
Hz, IrCH), 176.4 (s, O2CCH3), 133.3 (s, IrCHdCH), 25.3, 24.8  
(both s, O2CCH3 and C(O)CH3), 24.1 (vt, N ) 27.0 Hz,  
PCHCH3), 19.3, 18.9 (both s, PCHCH3). 31P NMR (36.3 MHz,  
C6D6): δ 24.4 (s, d in off-resonance).  
1
ν(CdO) 1565 cm-1. H NMR (200 MHz, CD2Cl2): δ 10.17 (br  
dd, J(H,H) ) 9.2 and 1.0 Hz, 1 H, IrCH), 7.50 (dt, J(H,H) )  
9.2, J(P,H) ) 1.9 Hz, 1 H, IrCHdCH), 2.56 (t, J(P,H) ) 1.8  
Hz, 3 H, C(O)CH3), 2.39 (m, 6 H, PCHCH3), 1.33, 1.18 (both  
dvt, N ) 14.9, J(H,H) ) 7.1 Hz, 18 H each, PCHCH3), -20.68  
(dt, J(H,H) ) 1.0, J(P,H) ) 12.7 Hz, 1 H, IrH). 13C NMR (50.3  
MHz, CD2Cl2): δ 216.7 (s, CdO), 203.5 (t, J(P,C) ) 9.2 Hz,  
IrCH), 175.9 (t, J(P,C) ) 8.1 Hz, IrCO), 139.8 (t, J(P,C) ) 2.4  
Hz, IrCHdCH), 26.5 (s, C(O)CH3), 25.7 (vt, N ) 29.3 Hz,  
PCHCH3), 18.9, 18.1 (both s, PCHCH3). 31P NMR (36.3 MHz,  
CD2Cl2): δ 25.5 (s, d in off-resonance), -144.5 (sept, J(P,F) )  
710.1 Hz, PF6-).  
Preparation of [IrH(Cl){η1-(Z)-CHdCHC(O)Me}(CO)-  
(PiPr3)2] (31). A solution of 2 (95 mg, 0.15 mmol) in benzene  
(5 mL) was stirred in a 50 mL autoclave under a CO pressure  
of 50 bar for 2 days at room temperature. After the pressure  
was reduced and the CO atmosphere replaced by argon, the  
solvent was evaporated in vacuo. The remaining yellow  
microcrystalline solid was washed twice with small amounts  
of hexane and dried: yield 89 mg (90%); mp 146 °C. Anal.  
Calcd for C23H48ClIrO2P2: C, 42.75; H, 7.49. Found: C, 43.18;  
H, 7.83. MS (70 eV): m/z (Ir) 646 (M+, 1), 618 (M+ - CO, 62),  
576 (M+ - CH2dCHC(O)Me, 100), 548 (M+ - CO-CH2dCHC-  
(O)Me, 52), 70 (CH2dCHC(O)Me+, 62). IR (KBr): ν(IrH) 2115,  
ν(CO) 2000, ν(CdO) 1665 cm-1. 1H NMR (90 MHz, CDCl3): δ  
8.70 (ddt, J(H,H) ) 12.0 and 4.7, J(P,H) ) 2.9 Hz, 1 H, IrCH),  
6.74 (dt, J(H,H) ) 12.0, J(P,H) ) 1.4 Hz, 1 H, IrCHdCH), 2.41  
(m, 6 H, PCHCH3), 1.83 (s, 3 H, C(O)CH3), 1.16 (dvt, N ) 14.2,  
J(H,H) ) 7.1 Hz, 36 H, PCHCH3), -8.14 (dt, J(H,H) ) 4.7,  
J(P,H) ) 15.8 Hz, 1 H, IrH). 13C NMR (50.3 MHz, CDCl3): δ  
199.2 (s, CdO), 178.9 (s, IrCO), 144.7 (t, J(P,C) ) 7.8 Hz,  
IrCH), 176.4 (s, O2CCH3), 129.6 (s, IrCHdCH), 32.1 (s, C(O)-  
CH3), 23.8 (vt, N ) 29.3 Hz, PCHCH3), 18.6, 18.4 (both s,  
PCHCH3). 31P NMR (36.3 MHz, C6D6): δ 18.0 (s, d in  
off-resonance).  
Preparation of [IrH(Cl){κ2(C,O)-CHdCHC(Me)dO}-  
(PMetBu2)2] (34). This compound was prepared analogously  
as described for 2, using 1 (120 mg, 0.13 mmol), PMetBu2 (120  
µL, 0.60 mmol), and methyl vinyl ketone (23 µL, 0.26 mmol)  
as starting materials. A yellow microcrystalline solid was  
obtained: yield 141 mg (85%); mp 127 °C.  
Preparation of [IrH(Cl){κ2(C,O)-C(OMe)dCHC(Me)d  
O}(PMetBu2)2] (35). This compound was prepared analo-  
gously as described for 2, using 1 (160 mg, 0.17 mmol),  
PMetBu2 (160 µL, 0.80 mmol), and MeOCHdCHC(O)Me (0.35  
µL, 0.35 mmol) as starting materials. The reaction mixture  
was stirred for 2 h at 80 °C. A white microcrystalline solid  
was obtained: yield 201 mg (87%); mp 182 °C dec.  
Preparation of [IrH(Cl){κ2(C,O)-CHdC(Me)CHdO}-  
(PMetBu2)2] (36). This compound was prepared analogously  
as described for 2, using 1 (120 mg, 0.13 mmol), PMetBu2 (120  
µL, 0.60 mmol), and methacrolein (22 µL, 0.26 mmol) as  
starting materials. The reaction mixture was stirred for 2 h  
at 80 °C. An orange microcrystalline solid was obtained: yield  
131 mg (79%); mp 149 °C dec.  
Preparation of [IrH(I){η1-(Z)-CHdCHC(O)Me}(CO)-  
(PiPr3)2] (32). This compound was prepared analogously as  
described for 31, using 29 (110 mg, 0.15 mmol) and CO (50  
bar) as starting materials. A light yellow microcrystalline solid  
was obtained: yield 103 mg (90%); mp 145 °C. Anal. Calcd for  
C23H48IIrO2P2: C, 37.39; H, 6.55. Found: C, 37.16; H, 6.72.  
Preparation of [IrH(Cl){κ2(C,O)-CHdC(iPr)CHdO}-  
(PMetBu2)2] (37). This compound was prepared analogously  
as described for 2, using 1 (120 mg, 0.13 mmol), PMetBu2 (120  
µL, 0.60 mmol), and CH2dC(iPr)C(O)H (26 µL, 0.26 mmol) as  
starting materials. The reaction mixture was stirred for 2 h  
at 80 °C. An orange microcrystalline solid was obtained: yield  
133 mg (77%); mp 142 °C dec.  
IR (KBr): ν(IrH) 2150, ν(CO) 2000, ν(CdO) 1670 cm-1 1H  
.
NMR (90 MHz, C6D6): δ 8.90 (ddt, J(H,H) ) 11.8 and 4.7,  
J(P,H) ) 2.2 Hz, 1 H, IrCH), 6.83 (dt, J(H,H) ) 11.8, J(P,H)  
) 1.5 Hz, 1 H, IrCHdCH), 2.68 (m, 6 H, PCHCH3), 1.91 (s, 3  
H, C(O)CH3), 1.21, 115 (both dvt, N ) 14.2, J(H,H) ) 7.0 Hz,  
18 H each, PCHCH3), -9.68 (dt, J(H,H) ) 4.7, J(P,H) ) 16.4  
Hz, 1 H, IrH). 31P NMR (36.3 MHz, C6D6): δ 10.4 (s, d in off-  
resonance).  
Formation of Compound 14 by Reductive Elimination  
from 31. A solution of 31 (70 mg, 0.11 mmol) in C6D6 (0.5 mL)  
was stirred for 2 h at 80 °C. After the solution was cooled to  
room temperature, the 1H and 31P NMR spectra revealed that  
the starting material was converted to the carbonyl complex  
14 and methyl vinyl ketone. The yield was virtually quantita-  
tive.  
Preparation of [IrH(Cl){κ2(C,O)-CHdCHC(NH2)dO}-  
(PMetBu2)2] (38). This compound was prepared analogously  
as described for 10, using 1 (150 mg, 0.16 mmol), PMetBu2  
(160 µL, 0.80 mmol), and acrylic acid amide (24 mg, 0.32 mmol)  
as starting materials. A white microcrystalline solid was  
obtained: yield 178 mg (86%); mp 216 °C dec.  
Preparation  
of  
trans-[IrCl(η2-CH2dCHCO2Me)-  
(PMetBu2)2] (39). This compound was prepared analogously  
as described for 15, using 1 (150 mg, 0.16 mmol), PMetBu2  
(160 µL, 0.80 mmol), and methyl acrylate (29 µL, 0.32 mmol)  
as starting materials. A red microcrystalline solid was ob-  
tained: yield 166 mg (78%); mp 90 °C dec.  
Preparation  
of  
trans-[IrCl{η2-(E)-CHCO2Med  
Formation of Compound 14 by Thermolysis from 6. A  
solution of 6 (100 mg, 0.17 mmol) in mesitylene (5 mL) was  
stirred for 3 h at 160 °C. After the solution was cooled to room  
temperature, the volatiles were evaporated in vacuo. The IR  
and H NMR spectra revealed that the carbonyl complex 14  
was exclusively formed.  
CHCO2Me}(PMetBu2)2] (40). Method a. A suspension of 1  
(150 mg, 0.16 mmol) in toluene (5 mL) was treated under  
continuous stirring first with PMetBu2 (160 µL, 0.80 mmol)  
and then with dimethyl fumarate (46 mg, 0.32 mmol). After  
the reaction mixture was stirred for 5 min at room tempera-  
ture, a red solution was formed. The solvent was evaporated  
in vacuo, the residue was dissolved in pentane (3 mL), and  
the solution was stored for 12 h at -78 °C. A red microcrys-  
talline solid precipitated, which was separated from the mother  
liquor, washed twice with small amounts of hexane (0 °C), and  
dried: yield 178 mg (77%).  
1
Preparation of [IrH(CO){κ2(C,O)-CHdCHC(Me)dO}-  
(PiPr3)2]PF6 (33). A solution of 2 (170 mg, 0.27 mmol) in  
dichloromethane (10 mL) was treated with KPF6 (184 mg, 1.00  
mmol) and stirred for 30 min under a CO atmosphere at room  
temperature. After CO was replaced by argon, the reaction  
Hydrido(vinyl)iridium(III) Complexes  
Organometallics, Vol. 24, No. 21, 2005 5139  
Method b. The procedure was the same as that described  
for method a, but instead of dimethyl fumarate the isomeric  
dimethyl maleate (41 µL, 0.32 mmol) was used as the sub-  
strate. Yield: 180 mg (78%); mp 83 °C.  
vacuo. The oily residue was dissolved in benzene/hexane (1:1,  
3 mL), and the solution was chromatographed on Al2O3  
(neutral, acctivity grade V, length of column 5 cm). With  
benzene/hexane (1:1) an orange fraction was eluted, which was  
brought to dryness in vacuo. An orange microcrystalline solid  
was obtained, which was washed twice with small quantities  
of pentane (0 °C) and dried: yield 116 mg (90%); mp 130 °C  
dec. Anal. Calcd for C20H46ClIrP2: C, 41.69; H, 8.05. Found:  
Preparation of [IrH(Cl){κ2(C,O)-CHdCHC(OMe)dO}-  
(PMetBu2)2] (41). This compound was prepared analogously  
as described for 17, using 39 (120 mg, 0.19 mmol) as starting  
material. A white microcrystalline solid was obtained: yield  
108 mg (90%); mp 145 °C dec.  
C, 41.30; H, 8.10. MS (70 eV): m/z (Ir) 576 (M+, 7), 548 (M+  
-
C2H4, 14), 28 (C2H4+, 100). H NMR (90 MHz, C6D6): δ 1.49  
(t, J(P,H) ) 4.4 Hz, 4 H, C2H4), 1.40 (vt, N ) 12.4 Hz, 36 H,  
PCCH3), 0.52 (vt, N ) 4.6 Hz, 6 H, PCH3). 31P NMR (36.3 MHz,  
C6D6): δ 9.8 (s).  
1
Preparation of [IrH(Cl){κ2(C,O)-C(CO2Me)dCHC(OMe)d  
O}(PMetBu2)2] (42). This compound was prepared analo-  
gously as described for 18, using 40 (120 mg, 0.18 mmol) as  
starting material. A yellow microcrystalline solid was obtained:  
yield 100 mg (83%); mp 179 °C dec.  
Generation of 44 and 45 from Compound 43. A suspen-  
sion of 1 (80 mg, 0.09 mmol) in benzene (5 mL) was treated  
under continuous stirring first with PMetBu2 (80 µL, 0.40  
mmol) and then with 43 (130 mg, 0.22 mmol). After the  
reaction mixture was stirred for 30 min at room temperature,  
an orange solution was formed. The solvent was evaporated  
in vacuo and the remaining orange solid identified as a 1:1  
mixture of 44 and 45 by IR and 1H and 31P NMR spectroscopy.  
Preparation  
of  
trans-[IrCl{η2-CH2dCHC(O)H}-  
(PMetBu2)2] (43). This compound was prepared analogously  
as described for 15, using 1 (140 mg, 0.15 mmol), PMetBu2  
(150 µL, 0.75 mmol), and acrolein (20 µL, 0.30 mmol) as  
starting materials. A red microcrystalline solid was obtained:  
yield 123 mg (65%); mp 92 °C dec.  
Generation of trans-[IrCl(CO)(PMetBu2)2] (44). A solu-  
tion of 43 (50 mg, 0.08 mmol) in benzene (5 mL) was stirred  
for 30 min at room temperature. A change of color from red to  
yellow occurred. After the solvent was evaporated in vacuo, a  
yellow microcrystalline solid was obtained. It was washed  
three times with small quantities of pentane and identified  
as trans-[IrCl(CO)(PMetBu2)2] (44) by comparison of the IR  
and NMR data with those of an authentic sample.30 The same  
product resulted if a solution of 43 in toluene was stirred for  
5 days at -30 °C.  
Acknowledgment. We thank the Deutsche For-  
schungsgemeinschaft (Grant SFB 347) and the Fonds  
der Chemischen Industrie for financial support. More-  
over, we gratefully acknowledge support by Mrs. R.  
Schedl and Mr. C. P. Kneis (elemental analysis and DTA  
measurements), Mrs. M.-L. Scha¨fer and Dr. W. Buchner  
(NMR spectra), and Dr. G. Lange and Mr. F. Dadrich  
(mass spectra).  
Preparation of trans-[IrCl(η2-C2H4)(PMetBu2)2] (45). A  
slow stream of ethene was passed for 30 s through a solution  
formed from 1 (100 mg, 0.11 mmol) and PMetBu2 (100 µL, 0.50  
mmol) in benzene (5 mL). After the solution was stirred for  
10 min at room temperature, the solvent was evaporated in  
Supporting Information Available: Complete list of  
analytical and spectroscopic data for complexes 34-43. This  
material is available free of charge via the Internet at  
http://pubs.acs.org.  
(30) Mann, B. E.; Masters, C.; Shaw, B. L.; Stainbank, R. E. J. Chem.  
Soc., Chem. Commun. 1971, 1103-1104.  
OM0505099  

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