Novel hydridoirida-β-diketones containing small molecules, CO, or ethylene: Their behavior in coordinating solvents such as dimethylsulfoxide or acetonitrile

Article abstract of DOI:10.1021/ic051219n

New hydridoirida-β-diketones [lrH{(PPh₂(o-C ₆H₄CO))₂H}(CO)]ClO₄ 2 and [IrH{(PPh₂(o-C₆H₄CO))₂H}(olefin)] BF₄ (olefin = C₂H₄,5; 1-hexene, 10) have been prepared. These complexes may afford new diacylhydridoiridium(III) derivatives. In chloroform solution, complex 2 is in equilibrium with the deprotonated diacylhydride trans-[IrH(PPh₂(O-C₆H₄-CO)) ₂(CO)] complex 3. In DMSO, deprotonation of 2 occurs to yield the kinetically favored product 3, which isomerizes to the thermodynamically favored complex cis-[IrH(PPh₂(o-C₆H₄CO)) ₂(CO)] 4. Reprotonation of 4 with HBF₄ in chlorinated solvents gives the cation in 2. In coordinating solvents such as dimethyl sulfoxide or acetonitrile, complex 5 undergoes displacement of ethylene to afford [IrH{(PPh₂(o-C₆H₄CO)) ₂H}(L)]BF₄ (L = DMSO, 7; CH₃CN, 9). Complexes 5 and 7 undergo deprotonation by NEt₃ to give the corresponding diacylhydrides. The ethylene complex gives only trans-[IrH(PPh ₂(o-C₆H₄CO))₂(C₂H ₄)] 6, while the dimethyl sulfoxide derivative affords a mixture of trans-and cis-[IrH(PPh₂(o-C₆H₄CO)) ₂(DMSO)] 8. Complex 10 shows inhibited alkene rotation around the Ir-olefin axis. All of the complexes were fully characterized spectroscopically. Single-crystal X-ray diffraction analysis was performed on complexes 3, 4, and 9. The ¹³C NMR and X-ray data point to a carbenoid character in the carbon atoms bonded to iridium in the irida-β-diketone fragment, so that it can be considered as an acyl(hydroxycarbene) moiety.

Full text of DOI:10.1021/ic051219n

Inorg. Chem. 2005, 44, 9084−9091
Novel Hydridoirida-â-diketones Containing Small Molecules, CO, or
Ethylene: Their Behavior in Coordinating Solvents Such as
Dimethylsulfoxide or Acetonitrile
Francisco Acha,† Mar´ıa A. Garralda,*,† Lourdes Ibarlucea,† Elena Pinilla,‡ and M. Rosario Torres‡
Facultad de Qu´ımica de San Sebastia´n, UniVersidad del Pa´ıs Vasco, Apdo. 1072, 20080 San
Sebastia´n, Spain, and Departamento de Qu´ımica Inorga´nica, Laboratorio de Difraccio´n de Rayos
X, Facultad de Ciencias Qu´ımicas, UniVersidad Complutense, 28040 Madrid, Spain
Received July 22, 2005
New hydridoirida-â-diketones [IrH{(PPh2(o-C6H4CO))2H}(CO)]ClO4 2 and [IrH{(PPh2(o-C6H4CO))2H}(olefin)]BF4 (olefin
)
C2H4, 5; 1-hexene, 10) have been prepared. These complexes may afford new diacylhydridoiridium(III) derivatives.
In chloroform solution, complex 2 is in equilibrium with the deprotonated diacylhydride trans-[IrH(PPh2(o-C6H4-
CO))2(CO)] complex 3. In DMSO, deprotonation of 2 occurs to yield the kinetically favored product 3, which isomerizes
to the thermodynamically favored complex cis-[IrH(PPh2(o-C6H4CO))2(CO)] 4. Reprotonation of 4 with HBF4 in
chlorinated solvents gives the cation in 2. In coordinating solvents such as dimethyl sulfoxide or acetonitrile, complex
5 undergoes displacement of ethylene to afford [IrH{(PPh2(o-C6H4CO))2H}(L)]BF4 (L ) DMSO, 7; CH3CN, 9).
Complexes 5 and 7 undergo deprotonation by NEt3 to give the corresponding diacylhydrides. The ethylene complex
gives only trans-[IrH(PPh2(o-C6H4CO))2(C2H4)] 6, while the dimethyl sulfoxide derivative affords a mixture of trans-
and cis-[IrH(PPh2(o-C6H4CO))2(DMSO)] 8. Complex 10 shows inhibited alkene rotation around the Ir−olefin axis.
All of the complexes were fully characterized spectroscopically. Single-crystal X-ray diffraction analysis was performed
on complexes 3, 4, and 9. The 13C NMR and X-ray data point to a carbenoid character in the carbon atoms
bonded to iridium in the irida-
â
-diketone fragment, so that it can be considered as an acyl(hydroxycarbene) moiety.
Introduction
o-(Diphenylphosphino)benzaldehyde (PPh2(o-C6H4CHO)) pro-
motes the chelate-assisted oxidative addition of aldehyde to
C-H bond cleavage in aldehydes, promoted by transition
metal complexes, is an active area of research.1 Rhodium
and iridium compounds oxidatively add aldehyde C-H
bonds to afford acylhydride derivatives,2 and this type of
species are believed to be involved in catalytic processes
such as aldehyde decarbonylation or alkene hydroacylation.3
several late transition metals in low oxidation states, yielding
cis acylhydride complexes that contain acylphosphine che-
lates (PPh2(o-C6H4CO)).4 Ir(III) complexes also react with
aldehyde C-H bonds to give decarbonylated alkyl or aryl
groups, or acylphosphine derivatives when using PPh2(o-
C6H4CHO) as the source of aldehyde, and these reactions
may involve iridium(V) intermediates formed by oxidative
addition of aldehyde to Ir(III) species.5
The reaction of [Ir(Cl)(H)(PPh2(o-C6H4CO))(Cod)] with
PPh2(o-C6H4CHO) in protic solvents allowed the preparation
of the first hydridoirida-â-diketone [IrH{(PPh2(o-C6H4-
CO))2H}Cl] 1a shown in Chart 1. Most likely, the reaction
occurs via an isomeric diacyldihydridoiridium(V) intermedi-
* To whom correspondence should be addressed. E-mail:
mariaangeles.garralda@ehu.es.
† Universidad del Pa´ıs Vasco.
‡ Universidad Complutense.
(1) (a) Marder, T. B.; Roe, D. C.; Milstein, D. Organometallics 1988, 7,
1451. (b) Gutie´rrez-Puebla, E.; Monge, A.; Paneque, M.; Poveda, M.
L.; Salazar, V.; Carmona, E. J. Am. Chem. Soc. 1999, 121, 248. (c)
Tellers, D. M.; Bergman, R. G. Organometallics 2001, 20, 4819.
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Organometallics 1982, 1, 1549. (c) Milstein, D.; Fultz, W. C.;
Calabrese, J. C. J. Am. Chem. Soc. 1986, 108, 1336. (d) Bianchini,
C.; Meli, A.; Peruzzini, M.; Vizza, F.; Bachechi, F. Organometallics
1991, 10, 820. (e) Bleeke, J. R.; Haile, T.; New, P. R.; Chiang, M. Y.
Organometallics 1993, 12, 517. (f) Wang, K.; Emge, T. J.; Goldman,
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Collman, J. P.; Hegedeus, L. S.; Norton, J. R.; Finke, R. G. Principles
and Applications of Organotransition Metal Chemistry, 2nd ed.;
University Science Books: Mill Valley, CA, 1987. (c) Jun, C. H.;
Hong, J. B.; Lee, D. Y. Synlett 1999, 1.
9084 Inorganic Chemistry, Vol. 44, No. 24, 2005
10.1021/ic051219n CCC: $30.25
© 2005 American Chemical Society
Published on Web 10/13/2005

NoWel Hydridoirida-â-diketones
Chart 1
Schlenk techniques. [IrH{(PPh2(o-C6H4CO))2H}X] (X ) Cl, 1a or
OClO3, 1b) was prepared as previously reported.6 Microanalysis
was carried out with a Leco CHNS-932 microanalyzer. Conductivi-
ties were measured in acetone solution with a Metrohm 712
conductimeter. IR spectra were recorded with a Nicolet FTIR 740
spectrophotometer in the range 4000-400 cm-1 using KBr pellets.
NMR spectra were recorded with a Bruker Avance DPX 300 or a
1
Bruker Avance 500 spectrometer; H and 13C{1H} (TMS internal
ate [Ir(Cl)(H)2(PPh2(o-C6H4CO))2] formed by oxidative ad-
dition of aldehyde to the starting Ir(III) species. The more
reactive [IrH{(PPh2(o-C6H4CO))2H}(OClO3)] 1b was also
prepared from 1a.6 Metalla-â-diketones were synthesized for
the first time by Lukehart by the protonation of diacylmeta-
late anions [LxM(COR)(COR′)]-,7 and more recently platina-
â-diketones have been reported, obtained by the reaction of
hexachloroplatinic acid with alkynes or by the reaction of
diacylhydridoplatinum(IV) complexes with TlPF6.8 Metalla-
â-diketones can be regarded as acyl(hydroxycarbene) com-
plexes stabilized intramolecularly by hydrogen bonds.8b,d
Hydroxycarbene complexes, for which a tautomeric equi-
librium with the acylhydrides has been reported,9 are
proposed as important intermediates in CO reduction reac-
tions,10 decarbonylation of aldehydes,2b or alkene hydrocar-
bonylation reactions to produce alcohols.11
standard), 31P{1H} (H3PO4 external standard), and 2D spectra were
measured from CDCl3 or DMSO-d6 solutions. Mass spectra were
recorded on a VG Autospec, by liquid secondary ion (LSI) MS
using nitrobenzyl alcohol as matrix and a cesium gun (Universidad
de Zaragoza).
Warning: Perchlorate salts and perchlorate transition metal
complexes may be explosive. Preparations at a larger scale than
that reported herein should be avoided.
Preparation of [IrH{(PPh2(o-C6H4CO))2H}(CO)]ClO4 (2).
Carbon monoxide at room temperature was bubbled for 30 min
through a dichloromethane solution of [IrH{(PPh2(o-C6H4CO))2H}-
(OClO3)] (1b) (0.06 mmol). The pale yellow complex was
precipitated by addition of diethyl ether, filtered off, washed with
diethyl ether, and vacuum-dried. IR (cm-1): 2128 (s), υ(Ir-H);
2037 (s), υ(CtO); 1628 (s), υ(CdO), 1093 (vs), υ(ClO4). ΛΜ (Ω-1
1
cm2 mol-1): 128. H NMR (CDCl3): δ -9.08 (t, 1H, J(P,H) )
16.6 Hz, IrH), 22.51 (s, br, 1H, OHO). 31P{1H} NMR (CDCl3): δ
17.9 (s). 13C{1H} NMR (CDCl3): δ 249.2 (d, J(P,C) ) 82 Hz,
CdO), 169.0 (t, J(P,C) ) 6 Hz, CtO). FAB MS: calcd for C39H30-
IrO3P2, 801; observed, 801 [M]+. Anal. Calcd for C39H30-
ClIrO7P2‚0.5CH2Cl2: C, 50.32; H, 3.31. Found: C, 50.57; H, 3.58.
Preparation of trans-[IrH(PPh2(o-C6H4CO))2(CO)] (3). To a
dichloromethane solution of complex 2 (0.06 mmol) was added a
stoichiometric amount of triethylamine (0.06 mmol). After being
stirred for 30 min at room temperature, the solution was washed
three times with distilled water and dried over magnesium sulfate.
Filtration, followed by addition of diethyl ether, gave a yellow solid
that was filtered off, washed with diethyl ether, and vacuum-dried.
IR (cm-1): 2068 (s), υ(Ir-H); 1990 (s), υ(CtO); 1645 (s),
We report here on the reactions of complexes 1 with
carbon monoxide or olefins to afford novel hydridoirida-â-
diketones, their characterization, and their behavior in
coordinating solvents such as dimethyl sulfoxide or aceto-
nitrile.
Experimental Section
General Procedures. The preparation of the metal complexes
was carried out at room temperature under nitrogen by standard
(4) (a) Rauchfuss, T. B. J. Am. Chem. Soc. 1979, 101, 1045. (b) Landvatter,
E. F.; Rauchfuss, T. B. Organometallics 1982, 1, 506. (c) Koh, J. J.;
Lee, W. H.; Williard, P. G.; Risen, W. M. J. Organomet. Chem. 1985,
284, 409. (d) Ghilardi, C. A.; Midollini, S.; Moneti, S.; Orlandini, A.
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Peruzzini, M.; Ramirez, J. A.; Vacca, A.; Vizza, F.; Zanobini, F.
Organometallics 1989, 8, 337. (f) Klein, H. F.; Lemke, U.; Lemke,
M.; Brand, A. Organometallics 1998, 17, 4196. (g) El Mail, R.;
Garralda, M. A.; Herna´ndez, R.; Ibarlucea, L.; Pinilla, E.; Torres, M.
R. Organometallics 2000, 19, 5310. (h) El Mail, R.; Garralda, M. A.;
Herna´ndez, R.; Ibarlucea, L. J. Organomet. Chem. 2002, 648, 149.
(i) Brockaart, G.; El Mail, R.; Garralda, M. A.; Herna´ndez, R.;
Ibarlucea, L.; Santos, J. I. Inorg. Chim. Acta 2002, 338, 249. (j)
Garralda, M. A.; Herna´ndez, R.; Ibarlucea, L.; Pinilla, E.; Torres, M.
R.; Zarandona, M. Inorg. Chim. Acta 2004, 357, 2818.
(5) (a) Luecke, H. F.; Bergman, R. G. J. Am. Chem. Soc. 1997, 119, 11538.
(b) Alaimo, P. J.; Arndtsen, B. A.; Bergman, R. G. Organometallics
2000, 19, 2130. (c) Nieuwenhuyzen, M.; Saunders, G. C. Inorg. Chim.
Acta 2004, 357, 2870.
(6) Garralda, M. A.; Herna´ndez, R.; Ibarlucea, L.; Pinilla, E.; Torres, M.
R. Organometallics 2003, 22, 3600.
1
υ(CdO). H NMR (CDCl3): δ -8.51 (t, 1H, J(P,H) ) 18.9 Hz,
IrH). 31P{1H} NMR (CDCl3): δ 21.1 (s). 13C{1H} NMR (CDCl3):
δ 220.7 (d, J(P,C) ) 85 Hz, CdO), 174.5 (s, br, CtO). FAB MS:
calcd for C39H29IrO3P2, 800; observed, 801 [M + H]+. Anal. Calcd
for C39H29IrO3P2: C, 58.57; H, 3.65. Found: C, 58.19; H, 3.21.
Preparation of cis-[IrH(PPh2(o-C6H4CO))2(CO)] (4). Stirring
of a dimethyl sulfoxide solution of complex 2 (0.06 mmol) for 48
h followed by addition of water gave a pale yellow solid that was
filtered off, washed with diethyl ether, and vacuum-dried. The solid
was recrystallized from CHCl3/diethyl ether. IR (cm-1): 2112 (m),
υ(Ir-H); 2023 (s), υ(CtO); 1623 (s), υ(CdO). 1H NMR
(CDCl3): δ -8.68 (dd, 1H, J(P,H)trans ) 110.2 Hz, J(P,H)cis
)
17.8 Hz, IrH). 31P{1H} NMR (CDCl3): δ 26.1 (d, J(P,P) ) 5 Hz),
21.6 (d). 13C{1H} NMR (CDCl3): δ 227.4 (t, J(P,C) ) 5 Hz,
CdO), 221.4 (d, J(P,C) ) 85 Hz, CdO), 175.3 (t, J(P,C) ) 5 Hz,
CtO). Anal. Calcd for C39H29IrO3P2‚1.75CHCl3: C, 48.52; H, 3.07.
Found: C, 48.52; H, 3.28.
(7) (a) Lukehart, C. M. AdV. Organomet. Chem. 1986, 25, 45. (b) Lukehart,
C. M.; Zeile, J. V. J. Am. Chem. Soc. 1976, 98, 2365.
(8) (a) Steinborn, D.; Gerish, M.; Merzweiler, K.; Schenzel, K.; Pelz, K.;
Bo¨gel, H. Organometallics 1996, 15, 2454. (b) Gerish, M.; Heinemann,
F. W.; Bruhn, C.; Scholz, J.; Steinborn, D. Organometallics 1999,
18, 564. (c) Nordhoff, K.; Steinborn, D. Organometallics 2001, 20,
1408. (d) Steinborn, D.; Gerish, M.; Bruhn, C.; Davies, J. A. Inorg.
Chem. 1999, 38, 680.
(9) Casey, C. P.; Czerwinski, C. J.; Fusie, K. A.; Hayashi, R. K. J. Am.
Chem. Soc. 1997, 119, 3971.
(10) Cornils, B., Herrmann, W. A., Eds. Applied Homogeneous Catalysis
with Organometallic Compounds; VCH: Weinheim, 1996.
(11) Cheliatsidou, P.; White, D. F. S.; Cole-Hamilton, D. J. J. Chem. Soc.,
Dalton Trans. 2004, 3425.
Preparation of [IrH{(PPh2(o-C6H4CO))2H}(C2H4)]BF4 ([5]-
BF4). Ethylene at room temperature was bubbled for 30 min through
a dichloromethane solution of complex [IrH{(PPh2(o-C6H4CO))2H}-
Cl] 1a (0.06 mmol) in the presence of AgBF4 (0.12 mmol). After
filtration of the silver salts, the addition of diethyl ether to the
solution gave a yellow precipitate that was filtered off, washed with
diethyl ether, and vacuum-dried. IR (cm-1): 2149 (m), υ(Ir-H);
1629 (s), υ(CdO); 1080 (vs), υ(BF4). ΛΜ (Ω-1 cm2 mol-1): 127.
1H NMR (CDCl3): δ -9.19 (t, 1H, J(P,H) ) 15.3 Hz, IrH), 2.52
Inorganic Chemistry, Vol. 44, No. 24, 2005 9085

Acha et al.
(s, 4H, C2H4), 22.25 (s, 1H, OHO). 31P{1H} NMR (CDCl3): δ 20.4
(s). 13C{1H} NMR (CDCl3): δ 256.4 (d, J(P,C) ) 85 Hz, CdO),
70.5 (s, C2H4). FAB MS: calcd for C40H34IrO2P2, 801; observed,
801 [M]+. Anal. Calcd for C40H34BF4IrO2P2‚0.25CH2Cl2: C, 53.19;
H, 3.83. Found: C, 53.38; H, 4.16.
Preparation of [IrH(PPh2(o-C6H4CO))2(C2H4)] (6). To a
dichloromethane solution of compound [5]BF4 (0.06 mmol) was
added a stoichiometric amount of triethylamine (0.06 mmol). After
being stirred for 30 min at room temperature, the solution was
washed three times with distilled water and dried over magnesium
sulfate. Filtration, followed by addition of diethyl ether, gave a
yellow solid that was filtered off, washed with diethyl ether, and
vacuum-dried. IR (cm-1): 2013 (s), υ(Ir-H); 1633 (s), υ(CdO).
1H NMR (CDCl3): δ -8.90 (t, 1H, J(P,H) ) 17.2 Hz, IrH), 2.31
(s, 4H, C2H4). 31P{1H} NMR (CDCl3): δ 23.2 (s). Anal. Calcd for
C40H33IrO2P2‚0.5CH2Cl2: C, 57.75; H, 4.07. Found: C, 57.77; H,
4.12.
Preparation of [IrH{(PPh2(o-C6H4CO))2H}(C6H12)]BF4 (10).
To a dichloromethane solution of [IrH{(PPh2(o-C6H4CO))2H}Cl]
1a (0.06 mmol) was added a 3-fold stoichiometric amount of
1-hexene (0.18 mmol) in the presence of AgBF4 (0.18 mmol).
Stirring for 30 min at room temperature followed by filtration of
the silver salts and addition of diethyl ether to the solution gave a
yellow precipitate that was filtered off, washed with diethyl ether,
and vacuum-dried. IR (cm-1): 2160 (w), υ(Ir-H); 1630 (m),
υ(CdO); 1083 (vs), υ(BF4). ΛΜ (Ω-1 cm2 mol-1): 104. 1H NMR
(CDCl3): δ -10.41 (dd, 1H, J(P,H) ) 14.2 and 16.7 Hz, IrH),
2.35 (m, 2H, dCH2), 3.07 (m, 1H, dCH), 1.9-0.5 (m, 9H, aliphatic
protons), 21.94 (s, 1H, OHO). 31P{1H} NMR (CDCl3): δ 20.7 (d,
J(P,P) ) 6 Hz), 20.3(d). 13C{1H} NMR (CDCl3): δ 257.2 (d, J(P,C)
) 97 Hz, CdO), 255.2 (d, J(P,C) ) 75 Hz, CdO), 94.5 (s, dCH),
68.8 (s, dCH2), 33.7, 33.1, 22.0 (s, -CH2), 13.6 (s, CH3). FAB
MS: calcd for C44H42IrO2P2, 857; observed, 773 [M - C6H12]+.
Anal. Calcd for C44H42BF4IrO2P2‚0.5CH2Cl2: C, 54.19; H, 4.39.
Found: C, 53.88; H, 4.32.
X-ray Structure Determination of 3, 4, and 9. Suitable crystals
for X-ray experiments were obtained by slow diffusion of diethyl
ether onto chloroform solutions of complexes 3 or 4 or dichloro-
methane solutions of complex 9. Data collection was carried out
on a Bruker Smart CCD diffractometer using graphite-mono-
chromated Mo KR radiation (λ ) 0.71073 Å) operating at 50 kV
and different values of intensity depending on the crystal. In all
cases, the data were collected over a hemisphere of the reciprocal
space by combination of three exposure sets. Each exposure of 20
or 30 s covered 0.3 in ω. The first 50 frames were recollected at
the end of the data collection to monitor crystal decay, and no
appreciable decay was observed. A summary of the fundamental
crystal and refinement data is given in Table 1.
Preparation of [IrH{(PPh2(o-C6H4CO))2H}(DMSO)]BF4 (7).
To a dichloromethane solution of [IrH{(PPh2(o-C6H4CO))2H}Cl]
1a (0.06 mmol) was added a stoichiometric amount of dimethyl
sulfoxide (0.06 mmol) in the presence of AgBF4 (0.12 mmol).
Stirring for 30 min at room temperature followed by filtration of
the silver salts and addition of diethyl ether to the solution gave a
yellow precipitate that was filtered off, washed with diethyl ether,
and vacuum-dried. IR (cm-1): 2160 (m), υ(Ir-H); 1627 (s), υ-
(CdO); 1097 (vs, br), υ(SdO) + υ(BF4). ΛΜ (Ω-1 cm2 mol-1):
1
99. H NMR (CDCl3): δ -15.71 (t, 1H, J(P,H) ) 16.3 Hz, IrH),
2.05 (s, 6H, CH3), 22.61 (s, 1H, OHO). 31P{1H} NMR (CDCl3): δ
22.1 (s). 13C{1H} NMR (CDCl3): δ 254.2 (d, J(P,C) ) 88 Hz,
CdO), 45.2 (s, CH3). FAB MS: calcd for C40H36IrO3P2S, 851;
observed, 851 [M]+. Anal. Calcd for C40H36BF4IrO3P2S‚0.5CH2-
Cl2: C, 49.63; H, 3.81; S, 3.27. Found: C, 49.55; H, 3.59; S, 3.18.
Preparation of [IrH(PPh2(o-C6H4CO))2(DMSO)] (8). To a
dichloromethane solution of complex 7 (0.06 mmol) was added a
stoichiometric amount of triethylamine (0.06 mmol). After being
stirred for 30 min at room temperature, the solution was washed
twice with distilled water and dried over magnesium sulfate.
Filtration, followed by addition of diethyl ether, gave a yellow solid
that was filtered off, washed with diethyl ether, and vacuum-dried.
IR (cm-1): 2108 (m, br), υ(Ir-H); 1629 (s), υ(CdO); 1114 (s),
υ(SdO). Data for 8a, 1H NMR (CDCl3): δ -14.78 (t, 1H, J(P,H)
) 17.4 Hz, IrH), 2.39 (s, 6H, CH3). 31P{1H} NMR (CDCl3): δ
25.0 (s). Data for 8b, 1H NMR (CDCl3): δ -8.72 (dd, 1H,
J(P,H)trans ) 117.0 Hz, J(P,H)cis ) 17.4 Hz, IrH), 1.93 (s, 3H, CH3),
3.46 (s, 3H, CH3). 31P{1H} NMR (CDCl3): δ 23.7 (d, J(P,P) ) 7
Hz), 22.7 (d). Anal. Calcd for C40H35IrO3P2S‚0.5CH2Cl2: C, 54.51;
H, 4.06; S, 3.59. Found: C, 54.33; H, 4.20; S, 3.33.
The structures were solved by Patterson function and conven-
tional Fourier techniques (SHELXS-97).12 The refinement for the
three structures was made by full-matrix least-squares on F2
(SHELXL-97).12 For all compounds, anisotropic parameters were
used in the last cycles of refinement for all non-hydrogen atoms
with some exceptions. Complex 4 crystallizes with two solvent
molecules and compound 9 with a molecule of solvent. For 4, one
-
of the solvent molecules, and for 9, all fluorine atoms of the BF4
anion and the chlorine atoms of the solvent molecule, only three
cycles have been refined anisotropically, and in subsequent cycles
their thermal parameters were kept constant. The hydrogen atoms
were included in calculated positions and refined riding on their
respective carbon atoms with the thermal parameter related to the
bonded atoms, with some exceptions. The hydride atoms in all
cases, the hydrogen atoms of the solvent molecules involved in
the hydrogen bond for 3, and the enolic hydrogen atom for 9 have
been found in a difference Fourier and included and refined riding
on the Ir atom or included and fixed. These features led to R1 values
of 0.0364, 0.0526, and 0.0527 for 3, 4, and 9, respectively. The
largest residual peaks in the final difference map are close to the
iridium atom in 3 and 9 and in the vicinity of a chlorine atom of
a solvent molecule in 4.
Preparation of [IrH{(PPh2(o-C6H4CO))2H}(CH3CN)]BF4 (9).
To a dichloromethane solution of [IrH{(PPh2(o-C6H4CO))2H}Cl]
1a (0.06 mmol) was added a stoichiometric amount of the
acetonitrile (0.06 mmol) in the presence of AgBF4 (0.12 mmol).
Stirring for 30 min at room temperature followed by filtration of
the silver salts and addition of diethyl ether to the solution gave a
yellow precipitate that was filtered off, washed with diethyl ether,
and vacuum-dried. IR (cm-1): 2318 (w), υ(CtN); 2185 (m), υ-
(Ir-H); 1624 (s), υ(CdO); 1083 (vs), υ(BF4). ΛΜ (Ω-1 cm2 mol-1):
Results and Discussion
The reaction of complex [IrH{(PPh2(o-C6H4CO))2H}-
(OClO3)] 1b with carbon monoxide leads to the displacement
of the perchlorate group to afford the cationic [IrH{(PPh2-
(o-C6H4CO))2H}(CO)]ClO4, complex 2, shown in Scheme
1, as confirmed by IR and conductivity measurements. The
1
114. H NMR (CDCl3): δ -18.44 (t, 1H, J(P,H) ) 14.0 Hz,
IrH), 1.56 (s, 3H, CH3), 22.62 (s, 1H, OHO). 31P{1H} NMR
(CDCl3): δ 26.0 (s). 13C{1H} NMR (CDCl3): δ 254.7 (d, J(P,C)
) 96 Hz, CdO), 119.9 (s, CtN), 2.3 (s, CH3). FAB MS: calcd
for C40H33IrNO2P2, 814; observed, 814 [M]+. Anal. Calcd for
C40H33BF4IrNO2P2‚CH2Cl2: C, 49.96; H, 3.58; N, 1.42. Found: C,
49.87; H, 3.56; N, 1.41.
(12) Sheldrick, G. M., SHELX-97, Program for Crystal Structure Deter-
mination; University of Go¨ttingen: Go¨ttingen, Germany, 1997.
9086 Inorganic Chemistry, Vol. 44, No. 24, 2005

NoWel Hydridoirida-â-diketones
Table 1. Crystal and Refinement Data for 3, 4, and 9
3
4
9
formula
Mr
C39H29O3P2Ir
799.76
[C39H29O3P2Ir]‚2CHCl3
1038.50
[C40H32N1O2P2Ir]BF4‚CH2Cl2
985.55
temp, K
cryst syst
space group
a, Å
b, Å
c, Å
296(2)
monoclinic
P2(1)
10.9317(8)
12.1008(8)
13.168(1)
296(2)
monoclinic
P2(1)/c
21.066(1)
11.1459(7)
17.538(1)
296(2)
triclinic
P-1
9.8373(7)
13.1332(9)
16.752(1)
98.297(1)
103.212(1)
102.556(1)
2013.3(2)
2
R (deg)
â (deg)
108.134(1)
90.621(1)
γ (deg)
V, Å3
1655.4(2)
2
4117.6(5)
4
Z
F(000)
788
2040
970
cryst dimens, mm
D(calcd), g cm-3
µ, mm-1
scan technique
data collected
0.18 × 0.18 × 0.06
0.30 × 0.30 × 0.12
0.16 × 0.15 × 0.12
1.605
1.675
1.624
4.166
æ and ω
(-11,-15,-17) to
(14,16,12)
1.63-28.79
10 558
3.747
æ and ω
(-27,-14,-22) to
(22,15,23)
1.93-28.80
25 591
3.583
æ and ω
(-11,-15,-19) to
(11,7,19)
1.28-25
10 576
6996 (Rint ) 0.079)
4996
θ
no. of reflns collected
no. of ind reflns
no. of reflns observed
I > 2σ(I)
7399 (Rint ) 0.029)
6086
9827 (Rint ) 0.065)
6668
Ra (observed reflns)
RwFb (all reflns)
0.036
0.073
0.053
0.147
0.053
0.114
2
2
2
a ∑[|F0| - |Fc|]/∑|F0|. b {∑[w(Fo - Fc )2]/∑[w(Fo )2]}1/2
.
a
field,15 is a triplet at 169.0 ppm with a small J(P,C) of 6 Hz.
The O---H---O resonance at low field is extremely broad at
room temperature. On lowering the temperature, the signal
sharpens and by -40 °C becomes a sharp singlet at 22.51
ppm. The chemical shift of the enolic proton in the cationic
species 2 is very close to that of the neutral parent irida-â-
diketone 1b.6 These chemical shifts appear at slightly lower
field than in rhena- or ferra-â-diketones, in the δ 19-21 ppm
range,7 and at even lower field than in platina-â-diketones,
in the δ 14-19 ppm range.8 This indicates a lower electron
density at the enolic H atom of these irida-â-diketones when
compared to other metalla-â-diketones. Neither the hydride
resonance nor the 31P NMR signal is modified on changing
the temperature. We therefore believe that the fluxionality
of 2 is due to a deprotonation/protonation equilibrium
inhibited at low temperature. This equilibrium can be shifted
toward the deprotonated or the protonated form by using the
appropriate reagent as shown in Scheme 1. The deprotonated
form, a diacylhydride species, can be obtained by addition
of triethylamine, which gives trans-[IrH(PPh2(o-C6H4CO))2-
(CO)] 3 (Scheme 1i). The neutral complex shows IR
absorptions at lower frequency than in 2 for both υ(CtO)
and υ(Ir-H), while the hydride, the phosphine, and also the
carbonyl resonances appear at slightly lower fields than in
the cationic species. In line with the disappearance of the
acyl(hydroxycarbene) character, the acyl resonance in 3
appears at higher field, 221 ppm, than in 2 (see Table 2). In
the FAB spectrum, the peak due to the protonated form is
observed. Addition of stoichiometric amounts of HBF4‚Et2O
to chloroform solutions of 3 allows the formation of the
cation in 2 (Scheme 1ii), although attempts to obtain the BF4
salt of 2 pure were unsuccessful. According to the IR
Scheme 1
a (i) DMSO or Et3N in CH2Cl2; (ii) HBF4 in chlorinated solvents; (iii)
protonated DMSO; (iv) HBF4 in chlorinated solvents.
IR spectrum shows a strong carbonyl absorption at 2037
cm-1, and a sharp absorption at 2128 cm-1 due to υ(Ir-H).
The trans disposition of both groups is confirmed by the
hydride resonance at -9.08 ppm,13 which appears as triplet
due to coupling with two cis phosphorus atoms (J(P,H) )
16.6 Hz).
According to the NMR data, the two acylphosphine
fragments are equivalent. The 31P{1H} NMR spectrum shows
a singlet at 17.9 ppm, and the 13C{1H} NMR spectrum shows
a doublet in the expected range for Ir(III) species with a
certain acyl(hydroxycarbene) character.6,14 The large J(P,C)
of 82 Hz confirms the presence of acyl groups trans to
phosphorus atoms. Consequently, with these findings, the
resonance due to the carbonyl group, at the expected higher
(13) Deutsch, P. P.; Eisenberg, R. J. Am. Chem. Soc. 1990, 112, 714.
(14) Santos, L. L.; Mereiter, K.; Paneque, M.; Slugovc, C.; Carmona, E.
New J. Chem. 2003, 27, 107.
(15) Deutsch, P. P.; Eisenberg, R. Organometallics 1990, 9, 709.
Inorganic Chemistry, Vol. 44, No. 24, 2005 9087

Acha et al.
Table 2. Selected IR Stretching Frequencies (cm-1) and NMR
Chemical Shifts (ppm) for Complexes 2 and 3
complex υ(Ir-H) υ(CtO) δ(IrH)
δ31P δ13(CtO) δ13(CdO)
2
3
2128 (s) 2037 (s) -9.08 (t) 17.9 (s) 169.0 (t)
249.2 (d)
2068 (s) 1990 (s) -8.51 (t) 21.1 (s) 174.5 (br) 220.7 (d)
spectrum, the solid obtained contained always a mixture of
[2]BF4 and 3, due to incomplete protonation.
Dimethyl sulfoxide also promotes the immediate depro-
tonation of 2 to afford 3. This is not surprising taking into
account that dimethyl sulfoxide undergoes protonation to
form the [H(DMSO)2]+ cation16 and that the dissolution of
IrCl3 in dimethyl sulfoxide affords [H(DMSO)2]trans-[IrCl4-
(DMSO)2].17 More unexpectedly, the deprotonation reaction
is followed by a slow isomerization (ca. 48 h) of 3 into cis-
[IrH(PPh2(o-C6H4CO))2(CO)] 4 as shown in Scheme 1iii. The
NMR data indicate the presence of two inequivalent acylphos-
phine fragments in 4. The hydride resonance at -8.68 {dd}
shows coupling with a trans and with a cis phosphorus atom,
while the 31P{1H} NMR spectrum consists of two doublets
due to two inequivalent cis phosphorus atoms. The 13C{1H}
NMR spectrum shows resonances due to an acyl group trans
to phosphorus, an acyl group cis to phosphorus, and the
carbonyl group as a triplet due to coupling with two cis
phosphorus atoms with equal J(P,C) coupling constants. This
isomerization reaction of 3 into 4 requires the presence of
an acid. Complex 3 remains unaltered in DMSO-d6 solution,
but the addition of stoichiometric amounts of HBF4 promotes
its transformation into complex 4, after ca. 48 h. Most likely,
the isomerization reaction involves the formation of hydrogen
bonding between the protonated dimethyl sulfoxide and the
oxygen of an acyl group. This interaction can be responsible
for the opening of the acylphosphine chelate to give the
thermodynamic reaction product with the hydride trans to
phosphine. It thus appears that the trans isomer 3 is the
kinetic product for the carbonyldiacylhydride complex and
the thermodynamic product is the cis isomer 4 with only
one phosphine group trans to acyl. Consequently with this,
attempts to protonate complex 4 in DMSO by addition of
HBF4 proved unsuccessful, but the addition of an excess of
HBF4 (4:HBF4 ) 1:3) in dichloromethane leads to its
immediate protonation with concomitant isomerization to
give 2 as shown in Scheme 1iv. We may conclude that the
formation of the corresponding hydridoirida-â-diketone
requires both phosphorus atoms and both acyl groups being
coplanar.
Figure 1. Perspective ORTEP plot of 3. H atoms, except H1, and the
labeling of some C atoms are omitted for clarity. The thermal ellipsoids
are at the 30% probability level.
Figure 2. Perspective ORTEP plot of 4. H atoms, except H1, H40, and
H41, and the labeling of some C atoms are omitted for clarity. The thermal
ellipsoids are at the 25% probability level.
the carbonyl group. While in complex 2 the hydride and the
CO group are mutually trans to each other, in complex 3
the hydride is trans to the phosphorus atom of one acylphos-
phine group and the carbonyl group is trans to the acyl group
of the other acylphosphine chelate. The distances comprising
the chelate ligands are in the expected ranges.15,18 The Ir-P
distances are equivalent within a given complex. These
distances and the Ir-C(carbonyl) distances are also equiva-
lent in both complexes 3 and 4, in agreement with the similar
structural trans influence of the hydride and the acyl
ligands.18b The Ir-C(acyl) distances are equivalent within a
given complex and also in both complexes 3 and 4. This is
also the case for the CdO(acyl) distances. These features
suggest a similar structural trans influence of the phosphine
and the carbonyl ligands for Ir(III). In 3 and 4, the Ir-C(acyl)
distances, average of 2.09(1) Å in both, are at least 0.04(1)
Å longer than the corresponding distances in the hydridoirida-
â-diketones 1a (2.01(1) Å) or 1b (2.04(1) Å),6 while the
CdO distances in 3 and 4, average of 1.22(1) Å, are
The molecular structures of compounds 3 and 4 are shown
in Figures 1 and 2. Selected bond distances and angles are
listed in Table 3. Both complexes are isomers, and 4
crystallizes with two molecules of solvent (chloroform) that
form hydrogen bonding with the oxygen atoms of the acyl
groups (see Table 3). The geometry about the metal atom is
distorted octahedral with four positions occupied by the
phosphorus and carbon atoms of two bidentate ligands and
the other two position occupied by one hydride ligand and
(18) (a) Clark, G. R.; Greene, T. R.; Roper, W. R. J. Organomet. Chem.
1985, 293, C25. (b) Cleary, B. P.; Eisenberg, R. J. Am. Chem. Soc.
1995, 117, 3510. (c) Jime´nez, M. V.; Sola, E.; Mart´ınez, A. P.; Lahoz,
F. J.; Oro, L. A. Organometallics 1999, 18, 1125. (d) Chan, A. S. C.;
Shieh, H. Inorg. Chim. Acta 1994, 218, 89.
(16) Calligaris, M.; Carugo, O. Coord. Chem. ReV. 1996, 153, 83.
(17) Cartwright, P. S.; Gillard, R. D.; Sillanpaa, E. R. J.; Valkonen, J.
Polyhedron 1988, 7, 2143.
9088 Inorganic Chemistry, Vol. 44, No. 24, 2005

NoWel Hydridoirida-â-diketones
a
Scheme 2
Table 3. Selected Bond Lengths (Å) and Angles (deg) for Complexes
3, 4, and 9 Including the Hydrogen-Bond Geometry
3
4
9
Ir-P1
2.357(2)
2.349(2)
2.066(7)
2.096(7)
1.8282
2.354(2)
2.349(2)
2.085(6)
2.087(7)
1.46(6)
2.363(2)
2.353(2)
1.97(1)
2.039(9)
1.5986
Ir-P2
Ir-C1
Ir-C20
Ir-H1
Ir-C39
Ir-N1
1.932(8)
1.922(8)
2.104(7)
1.281(9)
1.277(10)
C1-O1
C20-O2
C39-O3
C39-N1
1.219(8)
1.214(9)
1.120(9)
1.205(7)
1.240(7)
1.132(9)
1.09(1)
C1-Ir-C20
C1-Ir-P1
C20-Ir-P1
C1-Ir-P2
C20-Ir-P2
P1-Ir-P2
C1-Ir-C39
C1-Ir-N1
C20-Ir-C39
C20-Ir-N1
P1-Ir-C39
P1-Ir-N1
P2-Ir-C39
P2-Ir-N1
C1-Ir-H1
C20-Ir-H1
P1-Ir-H1
P2-Ir-H1
C39-Ir-H1
N1-Ir-H1
89.2(3)
87.6(3)
90.0(4)
83.0(3)
172.1(3)
170.9(3)
81.6(3)
81.0(2)
166.6(2)
167.3(2)
83.1(2)
104.9(1)
92.7(3)
83.3(2)
90.7(2)
167.4(2)
82.8(2)
104.8(1)
88.0(3)
a (i) Et3N in CH2Cl2; (ii) in DMSO; (iii) in CH3CN.
105.3(1)
otherwise [5]ClO4 loses ethylene readily and several attempts
to isolate it led only to mixtures of 1b and [5]ClO4. Complex
5 can be obtained pure and reasonably stable by using
noncoordinating anions such as tetrafluoroborate. The reac-
tion of [IrH{(PPh2(o-C6H4CO))2H}Cl] 1a with ethylene in
the presence of AgBF4 gives compound [IrH{(PPh2(o-C6H4-
CO))2H}(C2H4)]BF4 ([5]BF4) that has been completely
characterized by spectroscopic means and microanalysis. The
IR spectrum shows a sharp absorption at 2149 cm-1 due to
υ(Ir-H) and the υ(CdO) band at 1629 cm-1 due to
coordinated acyl.
93.3(3)
92.5(3)
91.3(2)
89.9(3)
99.5(2)
97.4(2)
167.8(3)
100.2(2)
99.7(2)
90.3(2)
63.6
89.9
84.0
112.8
86.8
91.5
79.0
83.3
178.4
85(2)
85(2)
168(2)
86(2)
83(2)
156.8
Hydrogen-Bond Geometry
Compound [5]BF4 contains two equivalent acylphosphine
fragments as shown by the appearance of a singlet at 20.4
ppm in the 31P{1H} NMR spectrum and a doublet at 256.4
ppm (J(P,C) ) 85 Hz) in the 13C{1H} NMR spectrum. In
the 1H NMR spectrum, a sharp singlet was observed for the
ethylene hydrogen atoms at 2.52 ppm, and in the 13C{1H}
NMR spectrum the η2-ethene gave rise to a signal at 70.5
ppm. The alkene rotation is not frozen out for this complex
down to 193 K as in other Ir(III) ethylene derivatives.20 The
1H NMR spectrum shows also a triplet for the hydride
resonance at -9.19 ppm with J(P,H) of 15.3 Hz along with
the sharp resonance of the O---H---O group at low field,
22.25 ppm, indicating the absence of proton dissociation at
room temperature. Compound [5]BF4 reacts with triethyl-
amine (Scheme 2i) to give the diacylhydride complex [IrH-
(PPh2(o-C6H4CO))2(C2H4)] 6 that shows the υ(Ir-H) absorp-
tion at a lower frequency than in the ionic [5]BF4. As in the
carbonyl case, both the hydride and the phosphine resonances
are shifted toward lower fields with respect to the cationic
species 5.
O1-H2
1.11
1.34
2.420(9)
O2-H2
O2----O1
C40-H40
C41-H41
C40-O2
C41-O1
O2‚‚‚‚H40
O1-H41
1.03(7)
1.03(7)
3.08(1)
3.12(1)
2.08(7)
2.05(7)
O1-H2-O2
C40-H40-O2
C41-H41-O1
159.6
161(6)
158(5)
0.04(1) Å shorter than the corresponding distances in 1a or
1b (1.27(1) Å) as a consequence of the disappearance of
the acyl(hydroxycarbene) character present in the complexes
containing a O---H---O moiety. The largest differences
between compounds 3 and 4 are found in the maximum
deviations of the best least-squares plane for the IrC1O1O2C20
atoms19 (0.287(7) and 0.490(6) Å) and also in the O1---O2
distances (2.805(8) and 3.431(9) Å) for 3 and 4, respectively.
These differences can be attributed to the different disposition
of the bidentate ligands, moreover to the formation of
hydrogen bonds in 4, as shown in Figure 2.
Dissolution of [5]BF4 in DMSO-d6 leads to the displace-
ment of ethylene to give complex [IrH{(PPh2(o-C6H4-
CO))2H}(DMSO)]BF4 7 in equilibrium with the deprotonated
[IrH{(PPh2(o-C6H4CO))2H}(OClO3)] 1b reacts with eth-
ylene with displacement of the perchlorate group to afford
the ionic compound [IrH{(PPh2(o-C6H4CO))2H}(C2H4)]ClO4
([5]ClO4), containing the cationic ethylene π-complex 5
shown in Scheme 2, as confirmed by NMR measurements.
This compound is stable only under ethylene atmosphere,
(20) (a) Barbaro, P.; Bianchini, C.; Meli, A.; Peruzzini, M.; Vacca, A.;
Vizza, F. Organometallics 1991, 10, 2227. (b) Alvarado, Y.; Boutry,
O.; Gutie´rrez, E.; Monge, A.; Nicasio, M. C.; Poveda, M. L.; Pe´rez,
P. J.; Ruiz, C.; Bianchini, C.; Carmona, E. Chem.-Eur. J. 1997, 3,
860. (c) Gutie´rrez-Puebla, E.; Monge, A.; Nicasio, M. C.; Pe´rez, P.
J.; Poveda, M. L.; Rey, L.; Ruiz, C.; Carmona, E. Inorg. Chem. 1998,
37, 4538. (d) Bruin, B.; Peters, T. P. J.; Wilting, J. B. M.; Thewissen,
S.; Smits, J. M. M.; Gal, A. W. Eur. J. Inorg. Chem. 2002, 2671.
(19) Nardelli, M. Parst 97; University of Parma: Parma, Italy, 1997.
Inorganic Chemistry, Vol. 44, No. 24, 2005 9089

Acha et al.
complex trans-[IrH(PPh2(o-C6H4CO))2(DMSO)] 8a (see
1
Scheme 2ii) as indicated by NMR. The H NMR spectrum
shows a triplet at -15.34 ppm (J(P,H) ) 17.2 Hz) due to
the hydride, while the O---H---O resonance in the low field
region is not observed, and the 31P{1H} NMR spectrum
shows a singlet at 23.9 ppm. The addition of dichloromethane
and diethyl ether to the DMSO solution led only to the acyl-
(hydroxycarbene) compound 7. The ability of the DMSO
ligand to displace monoolefins bonded to iridium has been
recently reported,21 and the exchange reaction undergone by
complex 5 probably involves initial dissociation of ethylene.
7 can be more easily obtained by the reaction of [IrH{(PPh2-
(o-C6H4CO))2H}Cl] 1a with DMSO in the presence of
AgBF4 (see Experimental Section). The hydride resonance
at -15.71 {t} ppm (J(P,H) ) 16.3 Hz) appears as expected
for S-coordinated dimethyl sulfoxide trans to the hydride.
Only one methyl resonance for the S-bound DMSO is
Figure 3. Perspective ORTEP plot of 9. H atoms, except H1 and H2, and
the labeling of some C atoms are omitted for clarity. The thermal ellipsoids
are at the 30% probability level.
in Scheme 2. Other spectral features for 9 are as expected
(see Experimental Section).
1
observed both in the H NMR and in the 13C{1H} NMR
The acetonitrile complex 9 crystallizes from CHCl3-
diethyl ether to afford single crystals suitable for X-ray
crystallography. Figure 3 shows the molecular structure of
9, and selected bond distances and angles are listed in Table
2. The crystal consists of [C40H32NO2P2Ir]+ mononuclear
cations, tetrafluoroborate anions, and solvent molecules. The
geometry about the metal atom is distorted octahedral with
four positions occupied by P-C of two bidentate ligands
bonded between them by a hydrogen bond and the other two
positions occupied by the hydride and the acetonitrile ligands
mutually trans. The Ir-C bond lengths, 1.98(1) and 2.04(1)
Å, are similar to those in previously reported irida-â-
diketones,6 shorter than those in complex 3, and longer than
those reported for carbene iridium compounds such as [CpIr-
(dCPh2)(PiPr3)] (1.904(5) Å)25 or [TpMe2Ir(dCPhR)] (1.914-
(12) Å).1b Both C-O distances, 1.28(1) Å, longer than those
in 3, agree with those reported for other metalla-â-diketones,
and the O1---O2 distance 2.420(9) Å is in accordance with
a strong hydrogen bridge bond in mononuclear complexes.6,7,8b
The O---H---O hydrogen bond appears to be slightly unsym-
metrical, and the O1-H2-O2 angle (159.6°) is consistent
with a nearly linear O---H---O hydrogen bond. The Ir-P
distances are as expected, and the Ir-N distance (2.104(7)
Å) is similar to those found for complexes in which the
acetonitrile and the hydride ligands are mutually trans.23,26
The iridacycle comprising the acyl(hydroxycarbene) group
is essentially planar. The maximum deviation of the best
least-squares plane for the IrC1O1O2C20 atoms is
0.0749(1) Å for C1. The dihedral angles between this plane
and the best least-squares planes of the IrC1C2C7P1 and
IrC20C21C26P2 atoms are 3.9(3)° and 4.3(3)°, respectively.
In complex 3, the corresponding dihedral angles are
19.7(2)° and 11.0(2)°, respectively. These features support
some extent of carbenoid character in the carbon atoms
bonded to iridium.27
spectra. The appearance of a sharp singlet at 22.61 ppm in
the H NMR spectrum indicates the presence of the acyl-
1
(hydroxycarbene) group and excludes the formation of
hydrogen bonds involving the dimethyl sulfoxide for which
the corresponding resonance would be expected at higher
field.22 This is confirmed by the 13C{1H} NMR that shows
a resonance at 254.2 ppm.
Complex 7 reacts with triethylamine to give the neutral
complex [IrH(PPh2(o-C6H4CO))2(DMSO)] 8 as a mixture of
two isomers, trans-[IrH(PPh2(o-C6H4CO))2(DMSO)] 8a and
the DMSO version of complex 3, cis-[IrH(PPh2(o-C6H4CO))2-
(DMSO)] 8b. Compound 8a shows the proton and phos-
phorus resonances expected for a hydride ligand trans to
sulfur and equivalent phosphorus atoms at lower field than
in the parent complex 7. One methyl resonance for the
1
S-bound DMSO is observed in the H NMR spectrum.
Complex 8b shows resonances in accordance with non-
equivalent phosphorus atoms with the hydride ligand trans
to phosphorus, and the methyl groups in the S-bound DMSO
give rise to two resonances.
In accordance with the reported ability of acetonitrile to
displace ethylene trans to hydride,23 the dissolution of the
ethylene complex [5]BF4 in acetonitrile affords [IrH{(PPh2-
(o-C6H4CO))2H}(CH3CN)]BF4 9, which can be more easily
obtained by the reaction of [IrH{(PPh2(o-C6H4CO))2H}Cl]
1a with acetonitrile in the presence of AgBF4. Complex 9
shows the υ(Ir-H) absorption (2185 cm-1) at higher
frequency than in complex 7 (υ(Ir-H), 2160 cm-1) and the
hydride resonance (-18.44 {t} ppm) at higher field than in
complex 7 (-15.71 {t} ppm). The combination of these data
suggests a lower trans influence for acetonitrile than for
DMSO.24 A NOESY spectrum of 9 shows a cross-peak
between the enolic H atom at 22.62 ppm and the acetonitrile
methyl group at 1.56 ppm and supports the structure shown
(21) Dorta, R.; Rozenberg, H.; Shimon, L. J. W.; Milstein, D. Chem.-Eur.
J. 2003, 9, 5237.
(22) Buchanan, J.; Hamilton, E. J. M.; Reed, D.; Welch, A. J. J. Chem.
Soc., Dalton Trans. 1990, 677.
(23) Sola, E.; Navarro, J.; Lo´pez, J. A.; Lahoz, F. J.; Oro, L. A.; Werner,
H. Organometallics 1999, 18, 3534.
(24) Olgemo¨ller, B.; Beck, W. Inorg. Chem. 1983, 22, 997.
(25) Ortmann, D. A.; Weberndo¨rfer, B.; Scho¨neboom, J.; Werner, H.
Organometallics 1999, 18, 952.
(26) (a) He, X. D.; Ferna´ndez-Baeza, J.; Chaudret, B.; Folting, K.; Caulton,
K. G. Inorg. Chem. 1990, 29, 5000. (b) Jime´nez, M. V.; Caballero,
J.; Sola, E.; Lahoz, F. J.; Oro, L. A. Inorg. Chim. Acta 2004, 357,
1948.
9090 Inorganic Chemistry, Vol. 44, No. 24, 2005

NoWel Hydridoirida-â-diketones
Scheme 3
also shows two resonances due to two acyl(hydroxycarbene)
fragments trans to phosphorus. Consequently, the hydride
resonance appears as a doublet of doublet due to coupling
to two inequivalent cis phosphorus atoms.
Conclusions
New hydridoirida-â-diketones derived from o-(diphenyl-
phosphine)benzaldehyde [IrH{(PPh2(o-C6H4CO))2H}(L)]+ (L
) CO, olefins), with carbenoid character in the acyl groups
bonded to iridium, have been prepared. The acyl(hydroxy-
carbene) moiety requires both phosphorus atoms and both
acyl groups being coplanar to be stable. DMSO or CH3CN
displace ethylene to afford new hydridoirida-â-diketones.
Deprotonation of the acyl(hydroxycarbene) group allows the
isolation of new diacylhydridoiridium(III) derivatives. For
the carbonyl complex, the trans-[IrH{(PPh2(o-C6H4CO))2H}-
(CO)] isomer is the kinetically favored compound and the
cis-[IrH{(PPh2(o-C6H4CO))2H}(CO)] is the thermodynami-
cally favored species. A lower trans influence for acetonitrile
than for DMSO ligands is observed in these Ir(III) complexes.
Terminal olefins such as 1-hexene, with higher steric
requirements than ethylene, can also form the corresponding
hydridoirida-â-diketone [IrH{(PPh2(o-C6H4CO))2H}(C6H12)]-
BF4 10, provided an excess of olefin is used if the reaction
is to go to completion (Scheme 3). The hydride functionality
is responsible for an IR absorption at 2160 cm-1 and for the
1
high field H NMR resonance at -10.41 ppm. These data
suggest that the hydride ligand is trans to the η2-coordinated
olefin for which the olefinic resonances appear at 2.35 and
1
3.07 ppm in the H NMR and at 94.5 and 68.8 ppm in the
13C{1H} NMR spectrum. A sharp proton resonance at 21.94
ppm confirms the presence of the O---H---O fragment. In
this case, the steric effects inhibit the alkene rotation around
the Ir-olefin axis, and as a consequence complex 10 contains
two inequivalent acylphosphine fragments. In the 31P{1H}
NMR spectrum, two close doublets at ca. 20 ppm are
observed due to two mutually cis phosphines (J(P,P) ) 6
Hz), and the low field 13C{1H} NMR region at ca. 256 ppm
Acknowledgment. Partial financial support from MCYT
of Spain (Project BQU2002-0129) UPV and Diputacio´n Foral
de Guipuzcoa is gratefully acknowledged.
Supporting Information Available: Crystallographic data files
of complexes 3, 4, and 9 in CIF format. This material is available
free of charge via the Internet at http://pubs.acs.org.
(27) Sunley, G. J.; Menanteau, P. C.; Adams, H.; Bailey, N. A.; Maitlis,
P. M. J. Chem. Soc., Dalton Trans. 1989, 2415.
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