Alkynes and diynes as precursors for organoiridium complexes containing iridium-carbon single and double bonds

Article abstract of DOI:10.1021/om9703393

Te in situ generated species [IrCl(C₈H₁₄)(PiPr₃)₂] as well as the dihydrido complex [IrH₂Cl(PiPr₃)₂] (15) were found to be quite reactive toward alkynes and diynes with either H

Full text of DOI:10.1021/om9703393

Organometallics 1997, 16, 4077-4088
4077
Alk yn es a n d Diyn es a s P r ecu r sor s for Or ga n oir id iu m
Com p lexes Con ta in in g Ir id iu m -Ca r bon Sin gle a n d
Dou ble Bon d s†,1
Helmut Werner,* Raimund W. Lass, Olaf Gevert, and J ustin Wolf
Institut fu¨r Anorganische Chemie der Universita¨t, Am Hubland, D-97074 Wu¨rzburg, Germany
Received April 22, 1997X
The in situ generated species [IrCl(C8H14)(PiPr3)2] as well as the dihydrido complex [IrH2-
Cl(PiPr3)2] (15) were found to be quite reactive toward alkynes and diynes with either H or
SiMe3 as substituents at the CtC and CtCCtC units. While the thermal or photochemical
reaction of [IrCl(C8H14)(PiPr3)2] with Me3SiCtCR (R ) Ph, Me, nBu, SiMe3, CH2OH, CMe2-
OSiMe3, CO2Et) led to trans-[IrCl{dCdC(SiMe3)R}(PiPr3)2] (3-9) for R ) CO2Et via the
isolated π-alkyne metal intermediate trans-[IrCl(η2-Me3SiCtCR)(PiPr3)2] (2), photolysis of
15 in the presence of Me3SiCtCCtCSiMe3 gave trans-[IrCl{dCdC(SiMe3)CtCSiMe3}-
(PiPr3)2] (19). Compound 19 was also obtained by thermal or photochemical rearrangement
of trans-[IrCl(η2-Me3SiCtCCtCSiMe3)(PiPr3)2] (18). The dihydrido complex 15 reacted with
HCtCCtCH at -60 °C to yield [{IrHCl(PiPr3)2}2(µ-CtCCtC)] (16) and with HCtCCtCSiMe3
to give [IrHCl(CtCCtCSiMe3)(PiPr3)2] (20), from which the vinylidene isomer trans-
[IrCl(dCdCHCtCSiMe3)(PiPr3)2] (22) was generated on heating. The reaction of 15 with
propargylic alcohols HCtCCR(R′)OH led to different types of products, depending on the
substituents R and R′. Whereas for R ) R′ ) iPr the five-coordinate alkynyl hydrido complex
[IrHCl{CtCC(iPr)dCMe2}(PiPr3)2] (23) was formed, the six-coordinate carbonyl hydrido vinyl
derivative [IrHCl{(E)-CHdCHPh}(CO)(PiPr3)2] (25) was isolated for R ) H and R′ ) Ph.
Treatment of 15 with HCtCCPh2OH afforded, via [IrHCl(CtCCPh2OH)(PiPr3)2] (27) or the
isomer trans-[IrCl(dCdCHCPh2OH)(PiPr3)2] (28), the allenylideneiridium(I) compound trans-
[IrCl(dCdCdCPh2)(PiPr3)2] (29) in excellent yield. Hydrogenation of 29 gave the allene
complex trans-[IrCl(η2-CH2dCdCPh2)(PiPr3)2] (30), the structure of which was determined
by X-ray crystallography. The substituted vinylideneiridium compound trans-[IrCl{dCdC-
(SiMe3)CtCCPh2OH}(PiPr3)2] (33) was obtained from [IrCl(C8H14)(PiPr3)2] and Me3-
SiCtCCtCCPh2OH via the isomeric π-alkyne complex 32 as isolated intermediate.
In tr od u ction
) Rh,6 Ir7), we were interested to find out whether the
analogy also exists for the silylated counterparts
Me3SiCtCR.
We have recently shown that not only terminal
alkynes HCtCR but also trimethylsilyl-, triphenylsilyl-,
and triphenylstannyl-substituted derivatives XCtCR (X
) SiMe3,2 SiPh3,3 SnPh34) can be converted in the
coordination sphere of rhodium(I) to the corresponding
vinylidenes.5 The metal-assisted isomerization proceeds
either thermally or photochemically and occurs more
rapidly for X ) SnPh3 than for X ) SiMe3 or SiPh3. Since
we knew that terminal alkynes HCtCR react with both
[RhCl(PiPr3)2]2 and the related iridium precursor [IrCl-
(C8H14)(PiPr3)2] to give square-planar complexes of the
general composition trans-[MCl(dCdCHR)(PiPr3)2] (M
In this paper we describe our investigations on the
reactivity of the labile cyclooctene derivative [IrCl-
(C8H14)(PiPr3)2] toward trimethylsilyl-substituted alkynes
and buta-1,3-diynes, the preparation of iridium alkynyl
hydrido, vinylidene, allenylidene, and diyne complexes
from [IrH2Cl(PiPr3)2] as the starting material, the
isolation of two binuclear iridium(III) compounds with
a “naked” C4 bridge, and the selective hydrogenation of
a metal-bonded allenylidene to an allene ligand.
Resu lts a n d Discu ssion
Vin ylid en eir id iu m (I) Com p lexes fr om SiMe3-
Su bstitu ted Alk yn es. The cyclooctene adduct [IrCl-
(C8H14)(PiPr3)2], generated in situ from [IrCl(C8H14)2]2
(1) and PiPr3,8 reacts with Me3SiCtCCO2Et in hexane
even at 0 °C to give the corresponding square-planar
† Dedicated to Professor Peter Maitlis on the occasion of his 65th
birthday.
X Abstract published in Advance ACS Abstracts, August 1, 1997.
(1) Vinylidene Transition-Metal Complexes. 42. Part 41: see: Wiede-
mann, R.; Fleischer, R.; Stalke, D.; Werner, H. Organometallics 1997,
16, 866-870.
(2) (a) Schneider, D.; Werner, H. Angew. Chem. 1991, 103, 710-
712; Angew. Chem., Int. Ed. Engl. 1991, 30, 700-702. (b) Werner, H.;
Baum, M.; Schneider, D.; Windmu¨ller, B. Organometallics 1994, 13,
1089-1097.
(6) (a) Garcia Alonso, F. J .; Ho¨hn, A.; Wolf, J .; Otto, H.; Werner, H.
Angew. Chem. 1985, 97, 401-402; Angew. Chem., Int. Ed. Engl. 1985,
24, 406-407. (b) Werner, H.; Garcia Alonso, F. J .; Otto, H.; Wolf, J . Z.
Naturforsch., B: Anorg. Chem., Org. Chem. 1988, 43, 722-726. (c)
Werner, H.; Brekau, U. Z. Naturforsch., B: Anorg. Chem., Org. Chem.
1989, 44, 1438-1446.
(3) Baum, M.; Windmu¨ller, B.; Werner, H. Z. Naturforsch., B:
Anorg. Chem., Org. Chem. 1994, 49, 859-869.
(4) Baum, M.; Mahr, N.; Werner, H. Chem. Ber. 1994, 127, 1877-
1886.
(5) Short reviews: (a) Werner, H. Nachr. Chem. Tech. Lab. 1992,
40, 435-444. (b) Werner, H. J . Organomet. Chem. 1994, 475, 45-55.
(7) (a) Ho¨hn, A.; Werner, H. Angew. Chem. 1986, 98, 745-746;
Angew. Chem., Int. Ed. Engl. 1986, 25, 737-738. (b) Ho¨hn, A.; Werner,
H. J . Organomet. Chem. 1990, 382, 255-272.
(8) Schulz, M. Diploma Thesis, Universita¨t Wu¨rzburg, 1988.
S0276-7333(97)00339-7 CCC: $14.00 © 1997 American Chemical Society

4078 Organometallics, Vol. 16, No. 19, 1997
Werner et al.
Sch em e 1a
Sch em e 2
orange-red solids which (with the exception of 7 and 8)
are thermally stable up to at least 100 °C. Typical
spectroscopic features of 3-9 are the low-field signals
in the 13C NMR spectra at δ 240-255 and 80-100,
which due to P-C coupling appear as triplets and are
assigned to the R-C and â-C vinylidene carbon atoms,
respectively. The 31P NMR spectra of 3-9 each display
a single resonance at δ ca. 29-34 which is shifted 11-
26 ppm downfield compared to that of the alkyne
complex 2.
With regard to the mechanism of isomerization of 2
to 9, we failed to find any evidence for a stepwise
rearrangement including the silyliridium(III) compound
[IrCl(SiMe3)(CtCCO2Et)(PiPr3)2] as an intermediate. In
contrast to this, the reaction of trans-[IrCl(HCtCR)-
(PiPr3)2] to give trans-[IrCl(dCdCHR)(PiPr3)2] proceeds
via the alkynylhydrido complex [IrHCl(CtCR)(PiPr3)2]
as an isolable intermediate.7 In this context it should
be noted that we recently described the preparation and
structural characterization of the five-coordinate stan-
nylrhodium(III) compound [Rh(SnPh3)(CtCPh)2(PiPr3)2],
which is formed from [Rh(η2-O2CMe)(PiPr3)2] and 2
equiv of Ph3SnCtCPh.10 This compound does not
rearrange to the isomer trans-[Rh(CtCPh){dCdC-
(SnPh3)R}(PiPr3)2]. Moreover, Milstein et al. reported
the reaction of trans-[IrCl(C2H4)(PEt3)2] with HSiR2OH,
which leads to the hydridosilylmetal derivatives [IrH-
(SiR2OH)Cl(PEt3)2] in almost quantitative yield.11 For
R ) iPr, the X-ray crystal structure analysis revealed
a slightly distorted trigonal-bipyramidal geometry around
the metal center.
In spite of the above-mentioned unsuccessful attempts
to isolate [IrCl(SiMe3)(CtCCO2Et)(PiPr3)2], related five-
coordinate silyliridium(III) complexes are stable, as is
evidenced by the synthesis of [IrHCl(SiMe3)(PiPr3)2] (10)
from [IrCl(C8H14)(PiPr3)2] and an equimolar amount of
HSiMe3. While the Me3Si-substituted alkyne- and
vinylideneiridium compounds 2 and 3-9 are quite
stable and can be handled in air for a short period of
time, complex 10 is thermolabile and extremely sensi-
tive to oxygen. An analytically pure sample has been
obtained by chromatography on silylated SiO2. The
spectroscopic data for 10 (in particular the chemical
shift of the hydride signal at δ -20.0) do not allow us
to unequivocally assign a square-pyramidal (sqp) or a
trigonal-bipyramidal (tbp) structure for the five-coordi-
nate species. Since for the related hydridoiridium(III)
compound [IrHCl(C6H5)(PiPr3)2] a tbp configuration has
been determined by X-ray crystallography,12 we favor
a similar structure also for 10 (see Scheme 2). With
regard to the formation of 10 from 1, PiPr3, and HSiMe3
it is interesting to note that attempts to prepare the
dichloro derivative [IrCl2(SiMe3)(PiPr3)2] in the same
a
L ) PiPr3.
alkyne complex trans-[IrCl(Me3SiCtCCO2Et)(PiPr3)2]
(2) in ca. 60% yield. Compound 2 (Scheme 1) is an
orange, only moderately air-sensitive solid which is
soluble in all common organic solvents and can be stored
under argon for weeks without decomposition. The
alkyne ligand is strongly electron-withdrawing, which
is shown by the decrease of the CtC stretching fre-
quency from 2150 cm-1 in free Me3SiCtCCO2Et to 1775
cm-1 in 2. The trans disposition of the triisopropylphos-
phine ligands is inferred from the observation of a
singlet in the 31P NMR spectrum at δ 17.9 and by the
two resonances for the diastereotopic PCHCH3 protons
1
in the H NMR spectrum, which appear as doublets of
virtual triplets.9 The 13C NMR spectrum of 2 displays
(in C6D6) two signals at δ 93.5 and 90.1, which show a
rather small P-C coupling and are assigned to the
carbon atoms of the CtC unit.
In contrast to Me3SiCtCCO2Et, related alkynes
Me3SiCtCR with R ) Ph, Me, nBu, SiMe3, CH2OH,
CMe2OSiMe3 do not react with 1 in hexane or toluene
at 0 °C. When the temperature is raised to 40-60 °C a
slow reaction occurs which leads, however, to the
formation of the vinylideneiridium(I) complexes 3-8 in
good yield. They are formed via the corresponding
alkyne compounds trans-[IrCl(Me3SiCtCR)(PiPr3)2] as
intermediates, since the IR and 31P NMR spectra taken
in the course of the reaction display signals which are
typical for both isomers. Attempts to separate the
isomeric vinylidene- and alkyneiridium compounds by
column chromatography failed. In the presence of
Al2O3, an enhanced isomerization of trans-[IrCl(Me3-
SiCtCR)(PiPr3)2] to 3-8 as well as a subsequent
reaction of the Me3Si-substituted vinylidene complexes
takes place (see below).
Compound 2, which at room temperature is quite
stable both in the solid state and in solution, rearranges
on photolysis in benzene to give the isomer trans-
[IrCl{dCdC(SiMe3)CO2Et}(PiPr3)2] (9) almost quanti-
tatively. The vinylidene complexes 3-9 are red or
(10) Werner, H.; Gevert, O.; Haquette, P. Organometallics 1997, 16,
803-806.
(11) Goikhman, R.; Aizenberg, M.; Kraatz, H.-B.; Milstein, D. J . Am.
Chem. Soc. 1995, 117, 5865-5866.
(12) Werner, H.; Ho¨hn, A.; Dziallas, M. Angew. Chem. 1986, 98,
1112-1114; Angew. Chem., Int. Ed. Engl. 1986, 25, 1090-1092.
(9) Harris, R. K. Can. J . Chem. 1964, 42, 2275-2281.

Organoiridium Complexes Containing Ir-C Bonds
Organometallics, Vol. 16, No. 19, 1997 4079
Sch em e 3a
a deep violet, very air-sensitive oil in about 50% yield.
We assume that 16 is structurally related to the
corresponding binuclear rhodium complex [{RhHCl-
(PiPr3)2}2(µ-CtCCtC)], which has been prepared from
[RhCl(PiPr3)2]2 and buta-1,3-diyne.15 The most char-
acteristic spectroscopic features of 16 are the hydride
resonance in the 1H NMR spectrum at δ -43.94
(comparable to the chemical shift for the metal-bonded
hydrogen of [IrHCl(CtCPh)(PiPr3)2] at δ -43.24)7b and
the two signals in the 13C NMR spectrum at δ 101.0
and 67.8, which are both split into triplets, due to P-C
coupling, and assigned to the IrCtC and IrCtC carbon
atoms, respectively.
a
The extremely labile buta-1,3-diynediyl complex 16
(which decomposes, for instance, during chromatogra-
phy on Al2O3) reacts quite rapidly with pyridine to give
the bis(pyridine) adduct 17 in nearly quantitative yield.
In contrast to 16, the corresponding binuclear compound
17 is only moderately air-sensitive and thus could be
characterized not only by IR and NMR spectroscopy but
also by elemental analysis. Owing to the different
coordination spheres around the metal centers in 16 and
L ) PiPr3.
way (i.e., from 1, PiPr3, and Me3SiCl) failed. It should
also be mentioned that the reaction of the in situ
generated species [IrCl(C8H14)(PiPr3)2] with 2 equiv of
HSiMe3 yields the dihydrido complex [IrH2Cl(PiPr3)2].13
The C-Si bond of the iridium vinylidenes can easily
be cleaved by protic reagents or by fluoride ions. After
chromatography of solutions of 3, 4, or 6 on deactivated
Al2O3 (activity grade V) in hexane, the H derivatives
trans-[IrCl(dCdCHR)(PiPr3)2] (11, 12) and trans-[IrCl-
(dCdCH2)(PiPr3)2] (13)7b are eluted instead of the
original product. Treatment of 9 with KF in the
presence of 18-crown-6 equally leads to cleavage of the
C-Si bond and to the formation of the hitherto unknown
complex 14 (Scheme 3). We assume that in this case
the sources for the proton at the â-C atom of the
vinylidene ligand are traces of water either in the
solvent or in KF. The properties as well as the
spectroscopic data of the red-violet solid 14 are similar
to those of trans-[IrCl(dCdCHCO2Me)(PiPr3)2], which
has been prepared from [IrH2Cl(PiPr3)2] and HCtCCO2-
Me and characterized by an X-ray crystal structure
analysis.14
1
17, in the H NMR spectrum of the latter the hydride
resonance is observed at δ -22.55, i.e., more than 21
ppm downfield compared to 16. The 13C NMR spectrum
of 17 displays the signals for the IrCtC and IrCtC
carbon atoms at δ 88.2 and 57.6, which is 10-13 ppm
upfield compared to those for the coordinatively unsat-
urated complex 16. A similar upfield shift is found in
the 31P NMR spectra, where the signal for the phos-
phorus nuclei of 16 appears at δ 39.3 and that of 17 at
δ 9.5.
Both IrC4Ir derivatives 16 and 17 cannot be con-
verted, either upon heating or upon UV irradiation, to
the binuclear compound [{IrCl(PiPr3)2}2(dCdCH-
CHdCd)] with a bridging bis(vinylidene) unit. Complex
16 with two five-coordinate iridium(III) centers thus
behaves differently from the mononuclear compounds
[IrHCl(CtCR)(PiPr3)2] (R ) Me, Ph), which in toluene
solution at 110 °C slowly rearrange to the vinylidene
isomers trans-[IrCl(dCdCHR)(PiPr3)2].7
Rea ction s of Ir id iu m (I) a n d Ir id iu m (III) P r ecu r -
sor s w ith Bu ta -1,3-d iyn es. Following our initial
studies on the synthesis of vinylideneiridium(I) com-
plexes from terminal alkynes,7,14a we attempted to
prepare buta-1,3-diynyl- and buta-1,3-diynediylirid-
ium(III) compounds from the in situ generated [IrCl-
(C8H14)(PiPr3)2] or from [IrH2Cl(PiPr3)2] (15) as the
starting material. If buta-1,3-diyne (which at room
temperature is a gas and as a pure substance is not easy
to handle due to its high tendency to polymerize) in
hexane solution is added dropwise to a solution of
[IrCl(C8H14)(PiPr3)2] in hexane at -78 °C, a rapid
change of color from yellow to dark brown occurs. When
the mixture is warmed to room temperature, a dark oily
The results concerning the reactivity of the starting
materials 1/PiPr3 and 15 toward Me3SiCtCCtCSiMe3
are summarized in Scheme 5. The in situ generated
species [IrCl(C8H14)(PiPr3)2] reacts rapidly with the
diyne, even at room temperature, to give the orange
crystalline compound 18 in ca. 75% yield. The fact that
only one of the CtC triple bonds of the diyne is
coordinated to the metal while the other is not is mainly
illustrated by the IR spectrum, in which, besides an
absorption at 1774 cm-1, typical for a π-bonded alkyne
at iridium(I),7b another band at 2114 cm-1 assigned to
ν(CtC) of an uncoordinated alkyne moiety is observed.
material is formed which according to the H and 13C
1
NMR spectra consists of a mixture of products. A minor
component is the dihydrido complex 15 (probably formed
by subsequent reactions of iridium(I)-containing inter-
mediates with cyclooctene),8 while a major component
seems to be the binuclear compound 16 (Scheme 4). This
species is obtained without a significant amount of
byproducts from 15 and buta-1,3-diyne in hexane at -60
°C and, after chromatographic workup, was isolated as
1
In agreement with this, there are two signals in the H
NMR spectrum of 18 for the protons of the two different
SiMe3 groups and four signals in the 13C NMR spectrum
for the carbon atoms of the coordinated and the un-
coordinated triple bonds.
In contrast to [IrCl(C8H14)(PiPr3)2], the dihydrido-
iridium(III) complex 15 is inert toward Me3-
SiCtCCtCSiMe3 at room temperature. However, it
reacts with the diyne slowly on UV photolysis to afford,
by elimination of H2, the vinylideneiridium(I) compound
(13) (a) Hietkamp, S.; Stufkens, D. J .; Vrieze, K. J . Organomet.
Chem. 1978, 152, 347-357.(b) Werner, H.; Wolf, J .; Ho¨hn, A. J .
Organomet. Chem. 1985, 287, 395-407.
(14) (a) Ho¨hn, A.; Otto, H.; Dziallas, M.; Werner, H. J . Chem. Soc.,
Chem. Commun. 1987, 852-854. (b) Werner, H.; Ho¨hn, A.; Schulz, M.
J . Chem. Soc., Dalton Trans. 1991, 777-781.
(15) Rappert, T.; Nu¨rnberg, O.; Werner, H. Organometallics 1993,
12, 1359-1364.

4080 Organometallics, Vol. 16, No. 19, 1997
Werner et al.
Sch em e 4a
a
L ) PiPr3.
Sch em e 5a
Sch em e 6a
a
L ) PiPr3.
1
mainly supported by the H NMR spectrum, in which
the hydride signal is observed at δ -42.19, i.e., at a
chemical shift similar to that for 16. Diagnostic for the
trans disposition of the two phosphine groups are the
two doublets of virtual triplets for the PCHCH3 protons
a
L ) PiPr3.
19 in moderate yield. A more efficient method to
prepare 19 consists of the thermal or photochemical
isomerization of 18, the photochemical route giving the
vinylidene complex nearly quantitatively. The red-
violet solid is air-stable (at least for hours) and, in
contrast to the related rhodium derivative,15 exceedingly
inert toward hydrolysis. The spectroscopic data for 19,
in particular the 13C NMR spectrum, clearly illustrate
the existence of a metal-vinylidene unit and also
confirm the different environments of the two SiMe3
groups.
The monosubstituted buta-1,3-diyne HCtCCtCSiMe3
reacts with the dihydrido complex 15 similarly to
terminal alkynes HCtCR. If equimolar amounts of 15
and the diyne are used, the diynylhydridoiridium(III)
compound 20 (Scheme 6) is formed and isolated as a
dark violet oil. Since it is very air-sensitive and
smoothly decomposes, even if stored at -20 °C under
argon, it has only been characterized by spectroscopic
techniques. The structural proposal with a square-
pyramidal configuration around the metal center and
a free coordination site trans to the hydride ligand is
1
in the H NMR and the virtual triplet for the PCHCH3
carbon atoms in the 13C NMR spectrum. The signal for
the 31P nuclei appears at δ 39.2 in the 31P NMR
spectrum and thus has the same chemical shift as in
16.
Similar to the binuclear complex 16, the mononuclear
species 20 reacts with pyridine to give the octahedral
1:1 adduct 21 in practically quantitative yield. The
spectroscopic data of the off-white crystalline solid are
similar to those of 17 and therefore deserve no further
comment.
In contrast to 21, which is rather inert and either on
heating in toluene at 80 °C or upon photolysis at room
temperature slowly decomposes, the five-coordinate
precursor rearranges in toluene at 60 °C to give the
alkynyl-substituted vinylideneiridium(I) isomer 22
(Scheme 6). The red-violet, moderately air-stable solid,
characterized by elemental analysis and IR and NMR
spectroscopy, is an analogue of the rhodium counterpart
trans-[RhCl(dCdCHCtCSiMe3)(PiPr3)2], which was not

Organoiridium Complexes Containing Ir-C Bonds
Organometallics, Vol. 16, No. 19, 1997 4081
Sch em e 7a
Sch em e 8a
a
L ) PiPr3.
complex [Ir{κ2(C,C)-C4(CO2Me)4}(PPh3)(CO)(CHdCHR)]
as the final product.17 Our observation that the deu-
terated compound [IrD2Cl(PiPr3)2] (15-d 2) reacts with
HCtCCH(Ph)OH to yield selectively [IrDCl(CHdCHPh)-
(CO)(PiPr3)2] (25-d ) seems to be in agreement with the
proposed mechanism.
However, an alternative route, which involves as an
initiating step the deprotonation of the IrCtCCH(Ph)-
OH unit by a hydridoiridium compound to give the
anionic species IrCtCCH(Ph)O-, cannot be ruled out.
Upon protonation, such a species could rearrange to an
intermediate containing an IrsCHdC(Ph)CHO moiety,
which by CO abstraction and recoordination of CO
would generate the Ir(CO)(CHdCHPh) unit. There is
precedence for the formation of compounds with an
IrsCHdC(R)C(R′)O fragment insofar as the above-
mentioned precursor [IrCl(C8H14)(PiPr3)2] reacts with
R,â-unsaturated aldehydes and ketones to give the
octahedral products [IrHCl{κ2(C,O)-CHdC(R)C(R′))O}-
(PiPr3)2] (R ) H, Me, iPr; R′ ) H, Me) in excellent
yield.18
a
L ) PiPr3.
prepared from the (unknown) buta-1,3-diynyl hydrido
isomer but from trans-[RhCl{dCdC(SiMe3)CtCSiMe3)-
(PiPr3)2] upon treatment with small amounts of water
in THF.15
R ea ct ivit y of P r op a r gylic Alcoh ols t ow a r d
[Ir H2Cl(P iP r 3)2]. The dihydridoiridium(III) compound
15 is highly reactive toward propargylic alcohols
HCtCCR(R′)OH but gives different types of products,
depending on the substituents R and R′. Dropwise
treatment of a solution of 15 in hexane with HCtCC-
(iPr)2OH at room temperature leads to a rapid change
of color from orange-yellow to red and, after chromato-
graphic workup, yields deep red crystals of the alkynyl
hydrido complex 23 (Scheme 7). The coordination of the
alkynyl anion is obviously accompanied by the elimina-
tion of water, thereby converting a CH(CH3)2 into a
1
dC(CH3)2 unit. The H NMR spectrum of 23 displays
the hydride signal at δ -44.0, which is at a position
similar to that for [IrHCl(CtCR)(PiPr3)2] (R ) H, Me,
Ph).7 The two doublets of virtual triplets for the
PCHCH3 protons confirm that the two phosphine ligands
are trans-disposed.
Compound 23 is quite inert and does not rearrange
to the vinylidene isomer trans-[IrCl{dCdCHC-
(iPr)dCMe2}(PiPr3)2] either on heating or on UV ir-
radiation. The corresponding rhodium derivative trans-
[RhCl{dCdCHC(iPr)dCMe2}(PiPr3)2] is known and has
been obtained by elimination of water from trans-
[RhCl{dCdCHC(iPr)2OH}(PiPr3)2] with NH4Cl as a
proton source.16
The carbonyl hydrido vinyl complex 25 is a colorless
solid which is air-stable and soluble in most common
organic solvents. Thermolysis of 25 in toluene-d8 for 2
h at 100 °C gives styrene and trans-[IrCl(CO)(PiPr3)2]
(26) nearly quantitatively. The most typical spectro-
scopic features of 25 are the strong ν(CO) absorption at
1996 cm-1 in the IR spectrum, the high-field signal for
the hydride ligand at δ -8.20, and the two resonances
for the vinylic protons at δ 8.07 and 6.73 (both doublets
1
of triplets) in the H NMR spectrum. The large H-H
coupling constant of the latter confirms the E configu-
ration at the CdC double bond. With regard to the
structural proposal for 25, as shown in Scheme 7, it
should be mentioned that the related complex [IrHCl-
(CHdCH2)(CO)(PiPr3)2], obtained by photochemical ac-
tivation of trans-[IrCl(C2H4)(PiPr3)2] in the presence of
CO, is known and has been characterized by X-ray
crystallography.19
The reaction of 15 with HCtCCH(Ph)OH surprisingly
affords the carbonyl hydrido vinyl complex 25 in 84%
yield (see Scheme 7). We assume that the expected
alkynylhydridoiridium(III) compound 24 is formed as
an intermediate, which is indicated by a signal at δ 38.5
in the 31P NMR spectrum of the reaction mixture at low
temperature. We note that the chemical shift of the 31
P
The reaction of 15 with HCtCCPh2OH takes a course
similar to that for [RhCl(PiPr3)2]2 with the same sub-
strate.16,20 In pentane at room temperature, the five-
coordinate alkynyl hydrido complex 27 (Scheme 8) is
formed and isolated as dark red crystals in 80% yield.
NMR resonance of 23 (δ 38.7) is almost identical. The
subsequent conversion of 24 to 25 could occur via an
allenylidene- and a (hydroxyallenyl)iridium intermedi-
ate. Recently, a similar mechanistic scheme has been
proposed by O’Connor and Hilbner for the reaction of
[Ir{κ2(C,C)-C4(CO2Me)4}(PPh3)2Cl] with HCtCCH(R)-
OH (R ) H, Me), which gives the carbonylvinylmetal
(17) O’Connor, J . M.; Hilbner, K. J . Chem. Soc., Chem. Commun.
1995, 1209-1210.
(18) Dirnberger, T.; Werner, H.; et al., manuscript in preparation.
See: Dirnberger, T. Dissertation, Universita¨t Wu¨rzburg, 1990.
(19) Schulz, M.; Werner, H. Organometallics 1992, 11, 2790-2795.
(20) Werner, H.; Rappert, T. Chem. Ber. 1993, 126, 669-678.
(16) Werner, H.; Rappert, T.; Wiedemann, R.; Wolf, J .; Mahr, N.
Organometallics 1994, 13, 2721-2727.

4082 Organometallics, Vol. 16, No. 19, 1997
Werner et al.
Sch em e 9a
F igu r e 1. Molecular structure (ORTEP plot) of compound
30.
a
L ) PiPr3.
recently generated in the coordination sphere of rhod-
ium with [RhH(CtCCPh2OH)2(PiPr3)2] as precursor,21
remained unsuccessful.
In agreement with the proposed structure, the CtC
stretching vibration is found at 2092 cm-1 in the IR
spectrum and the signal for the Ir-H proton at δ -43.6
in the 1H NMR spectrum. The single resonance at δ
40.3 for the 31P nuclei appears in the same region as
that of the analogous compound 23.
The alkynyl hydrido complex 27 can be stored for
weeks at 25 °C and even when it is warmed in toluene
at 70 °C only very slowly rearranges (accompanied by
partial decomposition) to the vinylidene isomer 28. The
isomerization is strongly facilitated, however, on UV
irradiation in hexane at room temperature, and then
28 is obtained almost quantitatively. The 1H NMR
spectrum of the red-violet, only slightly air-sensitive
compound displays a triplet at δ -3.29 instead of a
resonance at δ ca. -40 (as for 23 and 27), which is
diagnostic for a IrdCdCHR proton.7 In the 31P NMR
spectrum of 28, the signal for the two phosphine ligands
is observed at δ 30.5 and thus shifted 10 ppm upfield if
compared to 27.
An unexpected reaction occurs if a slow stream of
hydrogen is passed through a solution of 29 in CH2Cl2
(Scheme 9). Since 29, in a formal sense, is related to
26, we anticipated that with H2 either an oxidative
addition to yield a six-coordinate dihydridoiridium(III)
complex takes place or a five-coordinate allenyl hydrido
species is formed. However, the hydrogenation of 29
affords very cleanly the alleneiridium(I) derivative 30,
which is isolated as yellow crystals in 75% yield. The
1H NMR spectrum of 30 displays a signal at δ 1.79 for
the CH2 protons of the allene ligand, which due to P-H
coupling is split into a triplet. In the 13C NMR spec-
trum, the resonances for the carbon atoms of the
H2CdCdCPh2 unit appear at δ 151.6, 117.2, and -4.0;
the chemical shift of the last signal seems to be typical
for the signal of the CH2 carbon atom of a substituted
ligand.22
In order to substantiate the proposed structure of 30,
as shown in Scheme 9, an X-ray crystal structure
analysis was carried out. The ORTEP drawing (Fig-
ure 1) reveals that the iridium is coordinated in a
slightly distorted square-planar fashion. The two phos-
phine ligands are trans to each other, and the chlo-
rine atom is trans-disposed to the CdCH2 bond of the
allene moiety. The phosphorus-metal-phosphorus
axis is not exactly linear, the angle P1-Ir-P2 of
168.3(1)° being comparable to that in trans-[RhCl(η2-
Me3SiCtCCtCSiMe3)(PiPr3)2] [169.6(2)°].15 The in-
crease in length of the coordinated CdC bond (1.42(1)
vs 1.33(1) Å; see Table 1) is similar to that found in other
transition-metal allene complexes.22,23 The elongation
of the C1-C2 double bond in 30 is accompanied by a
bending of the allene ligand (angle C1-C2-C3 )
141.0(9)°), which is similar to those found in trans-
[RhCl(η2-CH2dCdCHCO2Et)(PiPr3)2] (141.8(5)°),22b and
[Pt(η2-CH2dCdCH2)(PPh3)2] (142(3)°).24 The bond dis-
tances Ir-C1 and Ir-C2 differ by ca. 0.10 Å, which is
in the range found for other four-coordinate transition-
metal allene derivatives.22,23
On treatment with catalytic amounts of CF3CO2H,
both isomers, 27 and 28, are converted to the allenyl-
idene derivative 29 (see Scheme 8). We assume that
the acid initiates the elimination of H2O, thereby
generating a cationic [IrHCl(dCdCdCPh2)(PiPr3)2]+
intermediate, which is converted to the final product by
dissociation of a proton. Compound 29 is also accessible
in excellent yield by photolysis of a solution of 27 in
CH2Cl2. Under these conditions, it is conceivable that
traces of HCl are formed which behave similarly to
CF3CO2H toward the starting material. The allenyl-
idene complex 29 is a dark red, moderately air-sensitive
solid, which is soluble in most organic solvents. As far
as the spectroscopic data are concerned, typical features
are the strong CdCdC stretching vibration at 1875
cm-1 in the IR spectrum and the three low-field reso-
nances for the carbon atoms of the IrdCdCdC chain
at δ 249.7, 199.3, and 138.7 in the 13C NMR spectrum.
As in the spectrum of the corresponding rhodium
compound trans-[RhCl(dCdCdCPh2)(PiPr3)2],20 the sig-
nal of the R-C atom of the allenylidene ligand appears
at higher field than that of the â-C atom, which is the
opposite to what is found for an IrdCdC unit.
(21) Werner, H.; Wiedemann, R.; Mahr, N.; Steinert, P.; Wolf, J .
Chem. Eur. J . 1996, 2, 561-569.
(22) (a) Werner, H.; Schwab, P.; Mahr, N.; Wolf, J . Chem. Ber. 1992,
125, 2641-2650. (b) Werner, H.; Schneider, D.; Schulz, M. J . Organo-
met. Chem. 1993, 451, 175-182.
In contrast to the vinylidene complex 28, which is
quite stable in the presence of carbon monoxide, the
allenylidene derivative 29 reacts smoothly with CO in
chloroform to give trans-[IrCl(CO)(PiPr3)2] (26). The
fate of the C3Ph2 fragment is not clear. Attempts to
detect the dimer Ph2CdCdCdCdCdCPh2, which was
(23) (a) Shaw, B. L.; Stringer, A. J . Inorg. Chim. Acta Rev. 1973, 7,
1-10. (b) Otsuka, S.; Nakamura, A. Adv. Organomet. Chem. 1976, 14,
245-283.
(24) Kadonaga, M.; Yasuoka, N.; Kasai, N. J . Chem. Soc. D 1971,
1597.

Organoiridium Complexes Containing Ir-C Bonds
Organometallics, Vol. 16, No. 19, 1997 4083
Sch em e 10a
Ta ble 1. Selected Bon d Dista n ces a n d An gles w ith
Esd ’s for Com p ou n d 30
Bond Distances (Å)
Ir-Cl
Ir-P1
Ir-P2
Ir-C1
2.356(3)
2.341(3)
2.362(3)
2.112(9)
Ir-C2
C1-C2
C2-C3
2.007(9)
1.42(1)
1.33(1)
Bond Angles (deg)
P1-Ir-P2
P1-Ir-Cl
P1-Ir-C1
P1-Ir-C2
P2-Ir-Cl
P2-Ir-C1
P2-Ir-C2
168.3(1)
87.5(1)
91.8(3)
92.9(3)
88.3(1)
89.0(3)
95.2(3)
Cl-Ir-C1
Cl-Ir-C2
Ir-C1-C2
Ir-C2-C1
Ir-C2-C3
C1-Ir-C2
C1-C2-C3
163.0(3)
156.9(3)
65.9(5)
74.0(5)
145.0(7)
40.1(4)
141.0(9)
Treatment of a solution of 30 in benzene for 36 h
under a H2 atmosphere leads to the hydrogenation of
the allene ligand, giving the olefin Ph2CdCHCH3 (31)25
and the original starting material 15 almost quantita-
tively. If one takes into consideration that 15 reacts
with HCtCCPh2OH to yield 27 (Scheme 8) and that this
complex can be converted via 29 to 30, the hydrogena-
tion of the latter compound to 15 and 31 implies that
the respective propargylic alcohol HCtCCPh2OH is
transformed into the olefin Ph2CdCHCH3. In this
context it seems worth mentioning that 31 is catalyti-
cally generated in the coordination sphere of rhodium(I)
from C2H4 and Ph2CN2 as precursors.5b,26
a
L ) PiPr3.
does not lead to the formation of the metallacumulene
trans-[IrCl(dCdCdCdCdCPh2)(PiPr3)2].27
Con clu sion s
The work presented in this paper has shown that
trimethylsilyl-substituted alkynes Me3SiCtCR can eas-
ily be converted not only in the coordination sphere of
rhodium(I) but also in that of iridium(I) to the isomeric
disubstituted vinylidenes :CdC(SiMe3)R. Although the
exact mechanism of the rearrangement is unknown, we
assume that the 1,2-SiMe3 shift, which for most of the
groups R occurs thermally, proceeds in a concerted way
possibly via an initial slippage of the alkyne to an η1
geometry.28 Such a reaction pathway has been consid-
ered as being energetically preferred for the 1,2-H shift
in the related compounds [M(η2-CH≡CR)Ln], provided
that the metal center has an 18-electron configuration.29
For the square-planar rhodium complexes trans-[RhCl-
(η2-HCtCR)(PR′3)2], however, a recent ab initio MO
study revealed that the isomerization proceeds via the
oxidative addition product [RhHCl(CtCR)(PR′3)2], fol-
lowed by a bimolecular hydrogen shift from the metal
to the terminal carbon atom of a second five-coordinate
molecule.30 The fact that in some cases the conversion
of a Me3Si-substituted alkyne to the corresponding
vinylidene is assisted by UV irradiation is not without
precedence and has been observed by us for rhodium
as the coordination center2 as well as by Sakurai in the
synthesis of [C5H5Mn(CO)2 {dCdC(SiMe2R)2}].31
The reactivity of the OH-functionalized diyne
Me3SiCtCCtCCPh2OH, which is a derivative of
HCtCCPh2OH, toward the labile starting material
[IrCl(C8H14)(PiPr3)2] has also been investigated. Orig-
inally, these studies were undertaken in order to
transform the Me3Si-substituted diynol into an
IrdCdCdCdCdCPh2 unit upon coordination, which
was finally achieved by using HCtCCtCCPh2OH as
the substrate.27 The reaction of Me3SiCtCCtCCPh2-
OH with [IrCl(C8H14)(PiPr3)2] in ether at room temper-
ature leads to the π-alkyne complex 32, which is related
to the above-mentioned compound 18 (see Scheme 5).
Due to similarities in the spectroscopic data for 18 and
32, we assume that the structural proposal for the
diynoliridium(I) complex 32 shown in Scheme 10 is more
likely than 32a . Whereas attempts to convert 32 to the
vinylidene derivative 33 by thermolysis or photolysis in
benzene failed, the desired isomerization takes place by
carefully heating a solid sample of 32 to 142 °C, which
is the melting point of the diynoliridium precursor.
Compound 33 is a red-violet, moderately air-sensitive
oil that has been characterized by elemental analysis
and IR and NMR spectroscopy. Typical spectroscopic
features for the vinylidene ligand are the low-field
signals in the 13C NMR spectrum at δ 252.8 and 82.0
(both triplets), which are assigned to the R-C and â-C
atoms of the IrdCdC chain and which possess chemical
shifts almost identical with those of 19. The substituted
vinylidene complex 33 is significantly more labile than
19 and decomposes even upon storing at 0 °C. Treat-
ment of 33 with (CF3SO2)2O in the presence of pyridine
From the synthetic point of view, the most remarkable
feature of this work is that the dihydridoiridium(III)
complex 15 is a versatile starting material not only for
the preparation of alkynylhydridoiridium(III) and di-
ynylhydridoiridium(III) but also for that of vinylidene-
and allenylideneiridium(I) derivatives. Since we failed
to detect an olefin or a diene as a byproduct, we assume
that in the initial step of the reaction a 1:1 adduct of
the five-coordinate compound 15 and the alkyne or diyne
(28) For a recent kinetic study on the interconversion between trans-
[RhCl(FcCtCSiMe3)(PiPr3)2] and trans-[RhCl{dCdC(SiMe3)Fc}(PiPr3)2]
(Fc ) ferrocenyl) see: Katayama, H.; Onitsuka, K.; Ozawa, F. Organo-
metallics 1996, 15, 4642-4645.
(29) Silvestre, J .; Hoffmann, R. Helv. Chim. Acta 1985, 68, 1461-
1506.
(25) (a) Hernandez, D.; Larson, G. L. J . Org. Chem. 1984, 49, 4285-
4287. (b) Hixson, S. S.; Franke, L. A. J . Org. Chem. 1988, 53, 2706-
2711.
(26) Wolf, J .; Brandt, L.; Fries, A.; Werner, H. Angew. Chem. 1990,
102, 584-586; Angew. Chem., Int. Ed. Engl. 1990, 29, 510-512.
(27) Lass, R. W.; Steinert, P.; Wolf, J .; Werner, H. Chem. Eur. J .
1996, 2, 19-23.
(30) Wakatsuki, Y.; Koga, N.; Werner, H.; Morokuma, K. J . Am.
Chem. Soc. 1997, 119, 360-366.
(31) Sakurai, H.; Fujii, T.; Sakamoto, K. Chem. Lett. 1992, 339-
342.

4084 Organometallics, Vol. 16, No. 19, 1997
Werner et al.
recrystallized from methanol (-78 °C) to give red-violet
is formed, followed by the reductive elimination of H2.
As to the formation of the allenylidene complex 29, we
note that most recently a square-planar cationic species
containing an IrdCdCdCPh2 unit has been prepared,
using [Ir(OMe)(dien)(PR3)] and HCtCCPh2OH as the
precursors.32 Finally, it should be mentioned that a
crystals: yield 69 mg (71%); mp 131 °C. Anal. Calcd for
C
29H56ClIrP2Si: C, 48.21; H, 7.81. Found: C, 47.92; H, 7.66.
IR (hexane): ν(CdC) 1585 cm-1 1H NMR (C6D6, 90 MHz): δ
.
7.75, 7.23, 6.87 (all m, 5H, C6H5), 2.82 (m, 6H, PCHCH3), 1.34
and 1.24 (both dvt, N ) 13.6, J (HH) ) 6.6 Hz, 18H each,
PCHCH3), 0.41 (s, 9H SiMe3). 13C NMR (C6D6, 22.5 MHz): δ
255.9 (t, J (PC) ) 11.2 Hz, IrdC), 127.5, 124.4, 120.9 (all s,
C6H5), 101.9 (t, J (PC) ) 2.4 Hz, IrdCdC), 24.2 (vt, N ) 26.4
cationic complex related to 17 with
a
linear
IrsCtCCtCsIr chain also is known, but in contrast
to 17 it has been obtained from [I(Ph)CtCCtC(Ph)I]-
X2 and not from buta-1,3-diyne as starting material.33
Hz, PCHCH3), 20.7, 20.3 (both s, PCHCH3), 1.0 (s, SiMe3). 31
NMR (C6D6, 36.2 MHz): δ 30.7 (s).
P
P r ep a r a tion of tr a n s-[Ir Cl{dCdC(SiMe3)Me}(P iP r 3)2]
(4). This compound was prepared as described for 3, using 1
(0.07 mmol), PiPr3 (0.27 mmol), and Me3SiCtCMe (0.13 mmol)
as starting materials: red-violet microcrystalline solid: yield
53 mg (57%); mp 112 °C dec. Anal. Calcd for C24H54ClIrP2Si:
C, 43.65; H, 8.24. Found: C, 43.34; H, 8.40. MS (70 eV): m/ z
Exp er im en ta l Section
All reactions were carried out under an atmosphere of
argon by Schlenk tube techniques. The starting materials
[IrCl(C8H14)2]2 (1),34 [IrH2Cl(PiPr3)2] (15),13 HCtCCtCH,35
HCtCCtCSiMe3,36
HCtCCH(Ph)OH,37
and
Me3-
660 (M+ for 193Ir, 35Cl). IR (KBr): ν(CdC) 1643 cm-1 1H NMR
.
SiCtCCtCCPh2OH38 were prepared as described in the
literature. Due to the high tendency for polymerization, the
diynes were stored in dilute solutions at -78 °C. NMR spectra
were recorded at room temperature on J EOL FX 90Q, Bruker
AC 200, and Bruker AMX 400 instruments, IR spectra on a
Perkin-Elmer 1420 infrared spectrophotometer, and mass
spectra on a Finnigan MAT 90 (70 eV) instrument. Melting
points were measured by DTA.
(C6D6, 200 MHz): δ 2.76 (m, 6H, PCHCH3), 1.99 (s, br, 3H,
tCCH3), 1.23 (dvt, N ) 13.5, J (HH) ) 6.7 Hz, 36H, PCHCH3),
-0.97 (s, 9H, SiMe3). 31P NMR (C6D6, 81.0 MHz): δ 31.1 (s).
P r ep a r a tion of tr a n s-[Ir Cl{dCdC(SiMe3)n Bu }(P iP r 3)2]
(5). This compound was prepared as described for 3, using 1
(0.07 mmol), PiPr3 (0.27 mmol), and Me3SiCtCnBu (0.13
mmol) as starting materials: red-violet microcrystalline
solid: yield 64 mg (68%); mp 109 °C. Anal. Calcd for
P r ep a r a tion of tr a n s-[Ir Cl(Me3SiCtCCO2Et)(P iP r 3)2]
(2). A suspension of 1 (79 mg, 0.09 mmol) in 10 mL of hexane
was treated, while being continuously stirred, with PiPr3 (72
µL, 0.35 mmol). A yellow solution was formed, which was
cooled to 0 °C, and then Me3SiCtCCO2Et (33 µL, 0.18 mmol)
was added dropwise. A change of color from yellow to orange-
red occurred. The reaction mixture was slowly warmed to
room temperature, the solvent was removed, and the remain-
ing residue was dissolved in 2 mL of hexane. When the
solution was stored for 12 h at -78 °C, orange-yellow, only
moderately air-sensitive crystals were formed which were
separated from the mother liquor and repeatedly washed with
small quantities of hexane (-20 °C): yield 72 mg (57%); mp
100 °C. Anal. Calcd for C26H56ClIrO2P2Si: C, 43.47; H, 7.86.
Found: C, 43.72; H, 8.04. IR (hexane): ν(CtC) 1775, ν(CdO)
C
27H60ClIrP2Si: C, 46.16; H, 8.61. Found: C, 45.86; H, 8.89.
IR (hexane): ν(CdC) 1630 cm-1 1H NMR (C6D6, 90 MHz): δ
.
2.96 (m, PCHCH3), 1.34 (dvt, N ) 13.4, J (HH) ) 6.2 Hz,
PCHCH3), 0.89 (m, 3H, (CH2)3CH3), 0.42 (s, 9H, SiMe3); signals
of (CH2)3 protons covered by signals of PiPr3 protons. 13C NMR
(C6D6, 100.6 MHz): δ 251.9 (t, J (PC) ) 10.1 Hz, IrdC), 95.1
(t, J (PC) ) 3.0 Hz, IrdCdC), 35.5 (s, dCHCH2), 23.6 (s, CH2),
23.1 (vt, N ) 26.2 Hz, PCHCH3), 20.4 (s, PCHCH3), 14.1 (s,
(CH2)3CH3), 11.4 (s, CH2), 0.7 (s, SiMe3). 31P NMR (C6D6, 36.2
MHz): δ 29.3 (s).
P r ep a r a tion of tr a n s-[Ir Cl{dCdC(SiMe3)2}(P iP r 3)2] (6).
This compound was prepared as described for 3, using 1 (0.07
mmol), PiPr3 (0.27 mmol), and Me3SiCtCSiMe3 (0.33 mmol)
as starting materials. Upon recrystallization from methanol
(-78 °C), orange crystals were obtained: yield 62 mg (64%);
mp 141 °C dec. Anal. Calcd for C26H60ClIrP2Si2: C, 43.46; H,
8.42. Found: C, 43.34; H, 8.18. IR (hexane): ν(CdC) 1608
1695, 1685 cm-1 1H NMR (C6D6, 90 MHz): δ 4.10 (q, J (HH)
.
) 7.1 Hz, 2H, CH2CH3), 2.50 (m, 6H, PCHCH3), 1.29 and 1.17
(both dvt, N ) 13.4, J (HH) ) 7.3 Hz, 18H each, PCHCH3),
1.07 (t, J (HH) ) 7.1 Hz, 3H, CH2CH3), 0.35 (s, 9H, SiMe3).
13C NMR (C6D6, 22.5 MHz): δ 150.0 (s, CO2Et), 93.5 (t, J (PC)
) 2.6 Hz, CtC), 90.1 (t, J (PC) ) 1.3 Hz, CtC), 60.0 (s,
CH2CH3), 21.6 (vt, N ) 23.6 Hz, PCHCH3), 18.9 (s, PCHCH3),
14.3 (s, CH2CH3), 0.2 (s, SiMe3). 31P NMR (C6D6, 36.2 MHz):
δ 17.9 (s).
P r ep a r a tion of tr a n s-[Ir Cl{dCdC(SiMe3)P h }(P iP r 3)2]
(3). A suspension of 1 (60 mg, 0.07 mmol) in 10 mL of hexane
was treated, while being continuously stirred at room tem-
perature, with PiPr3 (54 µL, 0.27 mmol) and, after a yellow
solution was formed, with Me3SiCtCPh (26 µL, 0.13 mmol).
The reaction mixture was slowly warmed to 60 °C and then
stirred for 2 h. A change of color from yellow to red-violet
occurred. When the mixture was cooled to room temperature,
the solvent was removed in vacuo, and the residue was
cm-1 1H NMR (C6D6, 90 MHz): δ 2.89 (m, 6H, PCHCH3), 1.36
.
(dvt, N ) 13.3, J (HH) ) 7.1 Hz, 36H, PCHCH3), 0.30 (s, 18H,
SiMe3). 13C NMR (C6D6, 22.5 MHz): δ 242.5 (t, J (PC) ) 10.8
Hz, IrdC), 82.3 (s, br, IrdCdC), 23.9 (vt, N ) 25.4 Hz,
PCHCH3), 20.6 (s, PCHCH3), 2.6 (s, SiMe3). 31P NMR (C6D6,
36.2 MHz): δ 31.5 (s).
P r ep a r a t ion of tr a n s-[Ir Cl{dCdC(SiMe3)CH 2OH }-
(P iP r 3)2] (7). A suspension of 1 (110 mg, 0.11 mmol) in 10
mL of benzene was treated, while being continuously stirred
at room temperature, with PiPr3 (95 µL, 0.49 mmol) and, after
a yellow solution was formed, with Me3SiCtCCH2OH (34 µL,
0.23 mmol). The reaction mixture was warmed to 45 °C and
stirred for 6 h. When the mixture was cooled to room
temperature, the solvent was removed in vacuo, and the
residue was extracted with 10 mL of methanol. The extract
was concentrated to ca. 3 mL and then stored at -78 °C. Red-
violet crystals precipitated, which were separated from the
mother liquor, washed twice with small quantities of methanol
(-20 °C), and dried: yield 109 mg (71%); mp 52 °C dec. Anal.
Calcd for C24H54ClIrOP2Si: C, 42.62; H, 8.05. Found: C, 42.45;
(32) Esteruelas, M. A.; Oro, L. A.; Schrickel, J . Organometallics
1997, 16, 796-799.
(33) Stang, P. J .; Tykwinski, R. J . Am. Chem. Soc. 1992, 114, 4411-
4412.
H, 8.20. IR (KBr): ν(OH) 3450, ν(CdC) 1625 cm-1 1H NMR
.
(34) van der Ent, A.; Onderdelinden, A. L. Inorg. Synth. 1973, 14,
92-95.
(C6D6, 200 MHz): δ 4.66 (s, br, 2H, CH2OH), 2.90 (m, 6H,
PCHCH3), 1.30 (m, 36H, PCHCH3), 0.24 (s, 9H, SiMe3). 13C
NMR (C6D6, 50.3 MHz): δ 251.6 (t, J (PC) ) 10.9 Hz, IrdC),
97.9 (t, J (PC) ) 2.5 Hz, IrdCdC), 42.4 (s, CH2OH), 23.0 (vt,
N ) 26.4 Hz, PCHCH3), 20.4, 20.1 (both s, PCHCH3), 0.3 (s,
SiMe3). 31P NMR (C6D6, 36.2 MHz): δ 32.1 (s).
(35) Niedballa, U. in Methoden der Organischen Chemie, 4th ed.;
Mu¨ller, E., Ed.; Thieme: Stuttgart, Germany, 1977, Vol. 5, Part 2a, p
922.
(36) Zweifel, G.; Rajagopalan, S. J . Am. Chem. Soc. 1985, 107, 700-
701.
(37) Midland, M. M. J . Org. Chem. 1975, 40, 2250-2252.
(38) Holmes, A. B.; J ennings-White, C. L. D.; Schulthess, A. H.;
Akinde, B.; Walton, D. R. M. J . Chem. Soc., Chem. Commun. 1979,
840-842.
P r epar ation of tr a n s-[Ir Cl{dCdC(SiMe3)CMe2OSiMe3}-
(P iP r 3)2] (8). This compound was prepared as described for

Organoiridium Complexes Containing Ir-C Bonds
Organometallics, Vol. 16, No. 19, 1997 4085
7, using 1 (0.11 mmol), PiPr3 (0.49 mmol), and Me3SiCtCCMe2-
OSiMe3 (0.23 mmol) as starting materials: red-violet micro-
crystalline solid; yield 124 mg (75%); mp 83 °C dec. Anal.
Calcd for C29H66ClIrP2Si2: C, 44.85; H, 8.57. Found: C, 45.29;
C
23H48ClIrO2P2: C, 42.75; H, 7.45. Found: C, 42.47; H, 7.42.
IR (CH2Cl2): ν(CdO) 1686, ν(CdC) 1605 cm-1 1H NMR (C6D6,
.
90 MHz): δ 4.11 (q, J (HH) ) 7.1 Hz, 2 H, CH2CH3), 2.87 (m,
6H, PCHCH3), 1.26 (dvt, N ) 13.7, J (HH) ) 6.6 Hz, 36H,
PCHCH3), 1.05 (t, J (HH) ) 7.1 Hz, 3H, CH2CH3), -2.27 (t,
J (PH) ) 2.3 Hz, 1H, dCHCO2Et). 31P NMR (C6D6, 36.2
MHz): δ 35.5 (s).
H, 8.92. IR (hexane): ν(CdC) 1620 cm-1 1H NMR (C6D6, 200
.
MHz): δ 2.95 (m, 6H, PCHCH3), 1.56 (s, 6H, CMe2), 1.36 (m,
36H, PCHCH3), 0.46, 0.16 (both s, 9H each, SiMe3). 31P NMR
(C6D6, 36.2 MHz): δ 28.6 (s).
P r ep a r a tion of [{Ir HCl(P iP r 3)2}2(µ-CtCCtC)] (16). A
solution of 15 (140 mg, 0.26 mmol) in 10 mL of hexane was
treated dropwise (very slowly) at -60 °C with a 0.04 M solution
of buta-1,3-diyne in hexane. A change of color from orange-
yellow to dark red occurred, and a dark violet oily material
precipitated at the wall of the tube. After the reaction mixture
was warmed to room temperature, the solution was filtered,
the filtrate was brought to dryness in vacuo, and the residue
was dissolved in 2 mL of CH2Cl2. The solution was chromato-
graphed on Al2O3 (neutral, activity grade V, height of column
10 cm). With CH2Cl2 a violet fraction was eluted, from which,
after removal of the solvent, a deep violet, very air-sensitive
oil was isolated: yield 70 mg (48%). The oil was characterized
by spectroscopic techniques. 1H NMR (CDCl3, 400 MHz): δ
3.07 (m, 12 H, PCHCH3), 1.29 (m, 72 H, PCHCH3; at 60 MHz
dvt, N ) 14.5, J (HH) ) 6.4 Hz), -43.94 (t, J (PH) ) 11.5 Hz,
2H, IrH). 13C NMR (CDCl3, 50.3 MHz): δ 101.0 (t, J (PC) )
1.9 Hz, IrCtC), 67.8 (t, J (PC) ) 13.4 Hz, IrC), 23.0 (vt, N )
27.3 Hz, PCHCH3), 19.8, 19.6 (both s, PCHCH3). 31P NMR
(CDCl3, 81.0 MHz): δ 39.3 (s).
P r ep a r a t ion of tr a n s-[Ir Cl{dCdC(SiMe3)CO2E t }-
(P iP r 3)2] (9). A solution of 2 (60 mg, 0.08 mmol) in 5 mL of
benzene was irradiated at room temperature with a 500 W
Hg lamp (Osram) for 3 h. The solvent was removed, the
residue was extracted with 10 mL of hexane, and the extract
was concentrated to ca. 2 mL in vacuo. When the solution was
stored at -78 °C for 12 h, red crystals were formed, which
were separated from the mother liquor, washed twice with
small quantities of hexane (-20 °C), and dried: yield 54 mg
(90%); mp 119 °C. Anal. Calcd for C26H56ClIrO2P2Si: C, 43.47;
H, 7.86. Found: C, 43.65; H, 8.11. IR (hexane): ν(CdO) 1678,
ν(CdC) 1590 cm-1
.
1H NMR (C6D6, 200 MHz): δ 4.08 (q,
J (HH) ) 7.2 Hz, 2H, CH2CH3), 2.87 (m, 6H, PCHCH3), 1.32
(dvt, N ) 13.7, J (HH) ) 6.6 Hz, 36H, PCHCH3), 1.05 (t, J (HH)
) 7.2 Hz, 3H, CH2CH3), 0.27 (s, 9H, SiMe3). 13C NMR (C6D6,
50.3 MHz): δ 254.1 (t, J (PC) ) 11.2 Hz, IrdC), 151.2 (s,
CO2Et), 97.4 (t, J (PC) ) 2.5 Hz, IrdCdC), 59.4 (s, CH2CH3),
25.0 (vt, N ) 26.2 Hz, PCHCH3), 20.4, 20.1 (both s, PCHCH3),
14.6 (s, CH2CH3), 0.2 (s, SiMe3).31P NMR (C6D6, 36.2 MHz): δ
34.0 (s).
P r ep a r a tion of [{Ir HCl(p y)(P iP r 3)2}2(µ-CtCCtC)] (17).
A solution of 16 (30 mg, 0.03 mmol) in 7 mL of CH2Cl2 was
treated with an excess of pyridine (1 mL) and stirred for 5
min at room temperature. A quick change of color from deep
violet to yellow-green occurred. The solvent was removed, the
residue was dissolved in 2 mL of CH2Cl2, and the solution was
chromatographed on Al2O3 (neutral, activity grade V, height
of column 5 cm). With CH2Cl2 a yellow fraction was eluted,
which was brought to dryness in vacuo. The residue was
recrystallized twice from CH2Cl2/pentane (1:20) to give a pale
yellow microcrystalline solid: yield 34 mg (85%); mp 116 °C
dec. Anal. Calcd for C50H96Cl2Ir2N2P4: C, 46.04; H, 7.42; N,
2.15. Found: C, 46.40; H, 7.34; N, 2.22. IR (CHCl3): ν(IrH)
P r ep a r a tion of tr a n s-[Ir HCl(SiMe3)(P iP r 3)2] (10).
A
suspension of 1 (150 mg, 0.17 mmol) in 10 mL of hexane was
treated, while being continuously stirred, with PiPr3 (138 µL,
0.67 mmol) and, upon being cooled to -20 °C, dropwise with
HSiMe3 (149 µL of a 2.2 M solution in MeOCH2CH2OMe; 0.33
mmol). A change of color from yellow to orange occurred. After
the reaction mixture was warmed to room temperature, it was
stirred for 5 min, and then the solvent was removed. The
residue was dissolved in 2 mL of hexane, and the solution was
chromatographed on silylated SiO2. With hexane, an orange
fraction was eluted, from which, after removal of the solvent,
an orange-yellow, very air-sensitive oil was isolated: yield 169
mg (84%). Anal. Calcd for C21H31ClIrP2Si: C, 41.96; H, 5.20.
2225, ν(CtC) 2010 cm-1 1H NMR (CDCl3, 400 MHz): δ 10.11,
.
1
Found: C, 42.31; H, 5.55. IR (hexane): ν(IrH) 2200 cm-1. H
7.69, 7.24 (all m, 10H, C5H5N), 2.93 (m, 12H, PCHCH3), 1.14
(dvt, N ) 13.3, J (HH) ) 6.5 Hz, 72H, PCHCH3), -22.55 (t,
J (PH) ) 15.6 Hz, 2H, IrH). 13C NMR (CDCl3, 50.3 MHz): δ
136.2, 123.6 (both s, C5H5N, third signal of pyridine carbon
atoms not observed), 88.2 (s, br, IrCtC), 57.6 (t, J (PC) ) 11.4
Hz, IrC), 23.4 (vt, N ) 26.7 Hz, PCHCH3), 19.1 (s, PCHCH3).
31P NMR (CDCl3, 81.0 MHz): δ 9.5 (s).
NMR (C6D6, 200 MHz): δ 2.60 (m, 6H, PCHCH3), 1.21 (dvt, N
) 13.3, J (HH) ) 6.4 Hz, 36H, PCHCH3), 0.63 (s, 9H, SiMe3),
-20.0 (t, J (PH) ) 13.9 Hz, 1H, IrH). 13C NMR (C6D6, 50.3
MHz): δ 24.2 (vt, N ) 25.0 Hz, PCHCH3), 21.4, 20.0 (both s,
PCHCH3), 10.7 (s, SiMe3). 31P NMR (C6D6, 81.0 MHz): δ 37.6
(s).
Rea ction of 3, 4, a n d 6 w ith Al2O3/H2O. A solution of 3,
4, or 6 (0.10 mmol) in 2 mL of hexane was passed over Al2O3
(neutral, activity grade V, height of column 10 cm). With
hexane, a red-violet fraction was eluted, which was concen-
trated to ca. 2 mL and again passed over Al2O3. This
procedure was repeated until no starting material could be
detected by 1H NMR spectroscopy. From the final eluted
fraction a violet solid was isolated, which was shown by 1H
and 13C NMR spectroscopy to be trans-[IrCl(dCdCHR)(PiPr3)2]
(11, 12) or trans-[IrCl(dCdCH2)(PiPr3)2] (13), respectively; the
yields were quantitative.
P r epar ation of tr a n s-[Ir Cl(dCdCHCO2Et)(P iP r 3)2] (14)
fr om 9. A solution of 9 (144 mg, 0.20 mmol) in 10 mL of ether
was treated with KF (15 mg, 0.26 mmol) and 18-crown-6 (8
mg, 0.03 mmol) and stirred for 8 h at 0 °C. After the mixture
was warmed to room temperature, the solvent was removed
in vacuo, the residue was dissolved in 2 mL of toluene, and
the solution was chromatographed on Al2O3 (neutral, activity
grade V, height of column 5 cm). With toluene a violet fraction
was eluted, which was brought to dryness in vacuo. The
residue was recrystallized from hexane (-78 °C) to give red-
violet crystals, which were separated from the mother liquor,
repeatedly washed with small quantities of pentane (-20 °C),
and dried: yield 68 mg (52 °C); mp 158 °C. Anal. Calcd for
P r ep a r a t ion of tr a n s-[Ir Cl(Me3SiCtCCtCSiMe3)-
(P iP r 3)2] (18). A suspension of 1 (159 mg, 0.18 mmol) in 20
mL of hexane was treated with PiPr3 (150 µL, 0.72 mmol), and
after it was stirred for 10 min at room temperature,
Me3SiCtCCtCSiMe3 (69 mg, 0.35 mmol) was added in small
portions. The reaction mixture was stirred for 10 min and
then filtered, and the filtrate was concentrated to ca. 2-3 mL
in vacuo. When this solution was stored for 12 h at -78 °C,
orange crystals precipitated, which were separated from the
mother liquor, washed twice with small quantities of pentane
(-20 °C), and dried: yield 192 mg (73%); mp 79 °C dec. Anal.
Calcd for C28H60ClIrP2Si2: C, 45.29; H, 8.14. Found: C, 45.40;
H, 8.34. IR (hexane): ν(CtC)uncoord 2114, ν(CtC)coord 1774
cm-1 1H NMR (CDCl3, 200 MHz): δ 2.57 (m, 6H, PCHCH3),
.
1.33 and 1.31 (both dvt, N ) 13.0, J (HH) ) 6.2 Hz, 18H each,
PCHCH3), 0.31, 0.19 (both s, 9H each, SiMe3). 13C NMR
(CDCl3, 50.3 MHz): δ 100.4, 94.8 (both s, CtCuncoord), 80.6 (t,
J (PC) ) 1.3 Hz, CtCcoord), 79.7 (t, J (PC) ) 2.1 Hz, CtCcoord),
21.8 (vt, N ) 24.0 Hz, PCHCH3), 20.4, 19.9 (both s, PCHCH3),
0.8, -0.4 (both s, SiMe3). 31P NMR (CDCl3, 81.0 MHz): δ 17.2
(s).
P r ep a r a tion of tr a n s-[Ir Cl{dCdC(SiMe3)CtCSiMe3}-
(P iP r 3)2] (19). (a) A solution of 18 (120 mg, 0.16 mmol) in 10
mL of hexane was heated for 15 h under reflux. After the

4086 Organometallics, Vol. 16, No. 19, 1997
Werner et al.
mixture was cooled to room temperature, the solvent was
removed, and the residue was dissolved in 2 mL of hexane.
The solution was stored for 12 h at -78 °C to give red-violet
crystals which were filtered, washed twice with small quanti-
ties of pentane (-20 °C), and dried: yield 80 mg (67%).
(b) A solution of 18 (80 mg, 0.11 mmol) in 5 mL of benzene
was irradiated at room temperature with a 500 W Hg lamp
(Osram) for 4 h. The solution was then worked up as described
for (a): yield 66 mg (82%).
room temperature, the solvent was removed, the residue was
dissolved in 2 mL of hexane, and the solution was chromato-
graphed on Al2O3 (neutral, activity grade V, height of column
6 cm). With hexane, a red-violet fraction was eluted, which
was brought to dryness in vacuo. The residue was dissolved
in 2 mL of boiling pentane, and after this solution was cooled
and stored at -78 °C, red-violet crystals were obtained: yield
53 mg (56%); mp 87 °C dec. Anal. Calcd for C25H52ClIrP2Si:
C, 44.79; H, 7.82. Found: C, 44.98; H, 8.04. IR (KBr): ν(CtC)
2108, ν(CdC) 1605 cm-1 1H NMR (CDCl3, 200 MHz): δ 2.93
.
(c) A solution of 15 (160 mg, 0.29 mmol) and Me3-
SiCtCCtCSiMe3 (56 mg, 0.28 mmol) in 10 mL of hexane was
irradiated at room temperature with a 500 W Hg lamp (Osram)
for 40 h. After the irradiation was stopped, the solution was
concentrated in vacuo to ca. 2 mL, and the concentrate was
chromatographed on Al2O3 (neutral, activity grade V, height
of column 7 cm). With benzene a red fraction was eluted, from
which red-violet crystals were isolated: yield 50 mg (23%); mp
114 °C dec. Anal. Calcd for C28H60ClIrP2Si2: C, 45.29; H, 8.14.
Found: C, 45.60; H, 8.30. IR (hexane): ν(CtC) 2106, ν(CdC)
(m, 6H, PCHCH3), 1.33 (dvt, N ) 13.8, J (HH) ) 6.7 Hz, 36H,
PCHCH3), 0.09 (s, 9H, SiMe3), -3.31 (t, J (PH) ) 2.5 Hz, 1H,
dCH). 31P NMR (CDCl3, 81.0 MHz): δ 32.8 (s).
P r epar ation of [Ir HCl{CtCC(iP r )dCMe2}(P iP r 3)2] (23).
A solution of 15 (160 mg, 0.29 mmol) in 10 mL of hexane was
treated dropwise, while being continuously stirred, with
HCtCC(iPr)2OH (41 mg, 0.29 mmol) at room temperature. A
quick change of color from orange-yellow to red occurred. The
solution was concentrated to ca. 2 mL in vacuo and then
chromatographed on Al2O3 (neutral, activity grade V, height
of column 5 cm). With hexane, a red fraction was eluted which
was brought to dryness in vacuo. The residue was dissolved
in 2 mL of acetone, and when this solution was stored for 12
h at -78 °C, deep red crystals were isolated: yield 142 mg
(72%); mp 71 °C dec. Anal. Calcd for C27H56ClIrP2: C, 48.38;
H, 8.42. Found: C, 48.69; H, 8.63. IR (KBr): ν(CtC) 2070
1593 cm-1
.
1H NMR (C6D6, 400 MHz): δ 2.88 (m, 6H,
PCHCH3), 1.37 and 1.31 (both dvt, N ) 13.7, J (HH) ) 6.8 Hz,
18H each, PCHCH3), 0.29, 0.23 (both s, 9H each, SiMe3). 13C
NMR (C6D6, 50.3 MHz): δ 253.7 (t, J (PC) ) 11.8 Hz, IrdC),
96.7 (s, CtC), 83.1 (t, J (PC) ) 2.4 Hz, CtC), 77.2 (t, J (PC) )
2.7 Hz, IrdCdC), 23.3 (vt, N ) 26.4 Hz, PCHCH3), 20.4, 20.3
(both s, PCHCH3), 0.9, -0.85 (both s, SiMe3). 31P NMR (C6D6,
81.0 MHz): δ 32.8 (s).
cm-1 1H NMR (CD2Cl2, 400 MHz): δ 3.14 (m, 6H, PCHCH3),
.
2.67 (sept, J (HH) ) 6.1 Hz, 1H, CH(CH3)2), 1.86, 1.70 (both s,
3H each, dC(CH3)2), 1.32 and 1.31 (both dvt, N ) 13.8, J (HH)
) 6.4 Hz, 18H each, PCHCH3), 0.96 (d, J (HH) ) 6.1 Hz, 6H,
CH(CH3)2), -43.98 (t, J (PH) ) 12.0 Hz, 1H, IrH). 13C NMR
(CD2Cl2, 100.6 MHz): δ 128.9, 128.5 (both s, CdC), 107.7 (t,
J (PC) ) 1.1 Hz, IrCtC), 80.8 (t, J (PC) ) 11.2 Hz, IrC), 34.2
(s, CH(CH3)2), 23.7 (s, CH(CH3)2), 23.5 (vt, N ) 26.8 Hz,
PCHCH3), 22.5 (s, CH(CH3)2), 20.1, 19.8 (both s, PCHCH3).
31P NMR (C6D6, 36.2 MHz): δ 38.7 (s).
P r ep a r a tion of [Ir HCl(CtCCtCSiMe3)(P iP r 3)2] (20). A
solution of 15 (96 mg, 0.17 mmol) in 10 mL of pentane was
treated dropwise at
0 °C with a 0.03 M solution of
HCtCCtCSiMe3 (5.7 mL, 0.17 mmol) in ether. A quick
change of color from yellow to red occurred. The solvent was
removed and the dark violet oily residue, which is very air-
sensitive and rapidly decomposes in methanol solution, was
characterized by spectroscopic techniques. IR (C6H6): ν(CtC)
2180, 2110 cm-1 1H NMR (CDCl3, 200 MHz): δ 2.96 (m, 6H,
.
PCHCH3), 1.16 and 1.14 (both dvt, N ) 14.0, J (HH) ) 6.8 Hz,
18H each, PCHCH3), 0.11 (s, 9H, SiMe3), -42.19 (t, J (PH) )
11.9 Hz, 1H, IrH). 13C NMR (C6D6, 50.3 MHz): δ 94.4, 92.5
(both s, IrCtC and CtC), 80.0 (t, J (PC) ) 11.2 Hz, IrC), 75.5
(s, CtC), 23.3 (vt, N ) 27.8 Hz, PCHCH3), 19.8, 19.5 (both s,
PCHCH3), 0.70 (s, SiMe3). 31P NMR (CDCl3, 81.0 MHz): δ 39.2
(s).
P r epar ation of [Ir HCl((E)-CHdCHP h )(CO)(P iP r 3)2] (25).
A solution of 15 (100 mg, 0.18 mmol) in 5 mL of hexane was
treated dropwise, while being continuously stirred, at room
temperature with HCtCCH(Ph)OH (24 mg, 0.18 mmol), which
led to a rapid change of color from orange-yellow to red. After
the solution was concentrated in vacuo to ca. 1 mL, a white
solid precipitated, which was filtered and recrystallized from
pentane. Upon storage for 12 h at -78 °C white crystals were
isolated: yield 101 mg (84%); mp 141 °C dec. Anal. Calcd for
P r epar ation of [Ir HCl(CtCCtCSiMe3)(py)(P iP r 3)2] (21).
To a solution of 20, which was generated in situ from 15 (66
mg, 0.12 mmol) in 5 mL of benzene and a 0.03 M solution of
HCtCCtCSiMe3 (4.0 mL, 0.12 mmol) in ether, was added an
excess of pyridine (ca. 0.2 mL). A quick change of color from
dark violet to yellow-brown occurred. After the solution was
stirred for 2-3 min at room temperature, it was concentrated
to ca. 1-2 mL in vacuo and then chromatographed on Al2O3
(neutral, activity grade V, height of column 5 cm). With
benzene, a pale yellow fraction was eluted, which was evapo-
rated in vacuo. The residue was dissolved in 2 mL of boiling
hexane, and when the solution was cooled to -78 °C almost
white crystals precipitated: yield 81 mg (90%); mp 92 °C dec.
Anal. Calcd for C30H57ClIrNP2Si: C, 48.08; H, 7.67; N, 1.87.
Found: C, 48.55; H, 7.99; N, 1.66. IR (KBr): ν(IrH) 2290,
C
26H50ClIrOP2: C, 46.73; H, 7.54. Found: C, 47.01; H, 7.46.
IR (KBr): ν(CO) 1996 cm-1 1H NMR (CDCl3, 400 MHz): δ
.
8.07 (dt, J (HH) ) 18.1, J (PH) ) 2.2 Hz, 1H, IrCH), 7.29, 7.22,
7.02 (all m, 5H, C6H5), 6.73 (dt, J (HH) ) 18.1, J (PH) ) 1.4
Hz, 1H, CHdCHPh), 2.71 (m, 6H, PCHCH3), 1.28 and 1.20
(both dvt, N ) 14.0, J (HH) ) 7.0 Hz, 18H each, PCHCH3),
-8.20 (t, J (PH) ) 14.8, 1H, IrH). 13C NMR (CDCl3, 50.3
MHz): δ 167.8 (t, J (PC) ) 8.0 Hz, CO), 144.9 (t, J (PC) ) 8.0
Hz, IrCH), 142.7 (t, J (PC) ) 1.6 Hz, ipso C of C6H5), 138.7 (t,
J (PC) ) 2.6 Hz, CHdCHPh), 128.0, 124.5, 124.1 (all s, C6H5),
24.3 (vt, N ) 28.6 Hz, PCHCH3), 19.2, 18.9 (both s, PCHCH3).
31P NMR (CDCl3, 81.0 MHz): δ 16.3 (s).
Th er m olysis of 25. A solution of 25 (45 mg, 0.07 mmol)
in 0.5 mL of toluene-d8 was heated in an NMR tube for 2 h at
100 °C. After the solution was cooled to room temperature, it
was chromatographed on Al2O3 (neutral, activity grade V,
height of column 3 cm). With toluene, first a colorless fraction
containing styrene (GC/MS) and then a yellow fraction con-
taining trans-[IrCl(CO)(PiPr3)2] (26) were eluted. Compound
26 was identified by IR and 1H NMR data.39
ν(CtC) 2180, 2115 cm-1 1H NMR (C6D6, 400 MHz): δ 10.10,
.
6.83, 6.47 (all m, 5H, C5H5N), 2.91 (m, 6H, PCHCH3), 1.08 and
1.05 (both dvt, N ) 13.5, J (HH) ) 6.5 Hz, 18H each, PCHCH3)
0.14 (s, 9H, SiMe3), -20.13 (t, J (PH) ) 15.3 Hz, 1H, IrH). 13C
NMR (C6D6, 100.6 MHz): δ 152.3, 136.6, 123.8 (all s, C5H5N),
95.6 (s, IrCtC), 85.1 (t, J (PC) ) 11.4 Hz, IrC), 85.0, 71.4 (both
s, CtC), 23.8 (vt, N ) 26.8 Hz, PCHCH3), 19.3, 19.3 (both s,
PCHCH3), 0.8 (s, SiMe3). 31P NMR (C6D6, 81.0 MHz): δ 9.8
(s).
P r epa r a tion of tr a n s-[Ir Cl(dCdCHCtCSiMe3)(P iP r 3)2]
(22). A solution of 20, which was generated in situ from 15
(77 mg, 0.14 mmol) in 10 mL of toluene and a 0.03 M solution
of HCtCCtCSiMe3 (4.7 mL, 0.14 mmol) in ether, was stirred
for 15 h at 60 °C. After the reaction mixture was cooled to
P r ep a r a tion of [Ir HCl(CtCCP h 2OH)(P iP r 3)2] (27). A
solution of 15 (140 mg, 0.26 mmol) in 5 mL of pentane was
treated with a solution of HCtCCPh2OH (54 mg, 0.26 mmol)
(39) (a) Strohmeier, W.; Onada, T. Z. Naturforsch., B: Anorg. Chem.,
Org. Chem. 1968, 23, 1377-1379. (b) Werner, H.; Ho¨hn, A. Z.
Naturforsch., B: Anorg. Chem., Org. Chem. 1984, 39, 1505-1509.

Organoiridium Complexes Containing Ir-C Bonds
Organometallics, Vol. 16, No. 19, 1997 4087
in 5 mL of pentane at room temperature. A rapid change of
color from orange-yellow to red occurred, and a red solid
precipitated. When the solution was stored at -78 °C, dark
red crystals were formed, which were separated from the
mother liquor, washed with small quantities of pentane (-20
°C), and dried: yield 154 mg (80%); mp 122 °C dec. Anal.
Calcd for C33H54ClIrOP2: C, 52.40; H, 7.20. Found: C, 52.69;
H, 8.13. IR (KBr): ν(OH) 3400, ν(IrH) 2310, ν(CtC) 2090
from the mother liquor, washed with small quantities of
pentane (-20 °C), and dried: yield 56 mg (75%); mp 115 °C
dec. Anal. Calcd for C33H54ClIrP2: C, 53.68; H, 7.35. Found:
C, 53.89; H, 7.36. IR (KBr): ν(CdC) 1670 cm-1
.
1H NMR
(CDCl3, 200 MHz): δ 8.60, 7.20 (both m, 10H, C6H5), 2.48 (m,
6H, PCHCH3), 1.79 (t, br, J (PH) ) 4.9 Hz, 2H, CdCH2), 1.29
and 1.16 (both dvt, N ) 13.4, J (HH) ) 6.5 Hz, 18H each,
PCHCH3). 13C NMR (C6D6, 50.3 MHz): δ 151.6 (t, J (PC) )
4.2 Hz, dCd), 144.6, 141.5, 128.3, 128.2, 127.8, 127.3, 125.4,
124.9 (all s, C6H5), 117.2 (t, J (PC) ) 1.8 Hz, CPh2), 21.2 (vt, N
) 25.0 Hz, PCHCH3), 20.5, 19.3 (both s, PCHCH3), -4.0 (s,
CH2). 31P NMR (CDCl3, 81.0 MHz): δ 21.0 (s).
Rea ction of 30 w ith H 2. A solution of 30 (50 mg, 0.07
mmol) in 5 mL of benzene was stirred under a H2 atmosphere
(1 atm) for 36 h at room temperature. No change of color could
be observed. The 1H NMR spectrum of the solution reveals
that both 15 and Ph2CdCHCH3 (31) were formed almost
quantitatively.
cm-1
.
1H NMR (C6D6, 400 MHz): δ 7.79, 7.17, 7.06 (all m,
10H, C6H5), 3.00 (m, 6H, PCHCH3), 1.16 and 1.15 (both dvt,
N ) 13.8, J (HH) ) 7.0 Hz, 18H each, PCHCH3), -34.61 (t,
J (PH) ) 11.8 Hz, 1H, IrH). 31P NMR (CDCl3, 81.0 MHz): δ
40.3 (s).
P r ep a r a tion of [Ir Cl(dCdCHCP h 2OH)(P iP r 3)2] (28). A
solution of 27 (80 mg, 0.11 mmol) in 10 mL of hexane was
irradiated for 5 h at room temperature with a 500 W Hg lamp
(Osram). The solution was concentrated to ca. 1 mL in vacuo
and then stored for 12 h at -78 °C. Red-violet crystals
precipitated, which were separated from the mother liquor,
washed with small quantities of pentane (-20 °C), and dried:
P r ep a r a tion of tr a n s-[Ir Cl(Me3SiCtCCtCCP h 2OH)-
(P iP r 3)2] (32). A suspension of 1 (140 mg, 0.16 mmol) in 10
mL of ether was treated with PiPr3 (130 µL, 0.64 mmol) and
stirred for 5 min at room temperature. To the yellow solution
was added dropwise a solution of Me3SiCtCCtCCPh2OH (101
mg, 0.33 mmol) in 5 mL of ether, which led to a change of
color to orange. The reaction mixture was stirred for 10 min
and then concentrated to ca. 2 mL in vacuo. After 10 mL of
methanol was added and the solution was stirred for 12 h at
-78 °C, orange crystals were formed, which were separated
from the mother liquor, washed with small quantities of
methanol (0 °C), and dried: yield 210 mg (77%); mp 142 °C.
Anal. Calcd for C38H62ClIrOP2Si: C, 53.53; H, 7.33. Found:
C, 53.07; H, 6.97. IR (hexane): ν(OH) 3400, ν(CtC)uncoord 2105,
yield 74 mg (92%); mp 116 °C dec. Anal. Calcd for C33H54
ClIrOP2: C, 52.40; H, 7.20. Found: C, 52.48; H, 7.35. IR
(CH2Cl2): ν(OH) 3390, ν(CdC) 1663 cm-1 1H NMR (C6D6, 400
-
.
MHz): δ 7.49, 7.10, 6.99 (all m, 10H, C6H5), 2.85 (m, 6H,
PCHCH3), 1.23 (dvt, N ) 13.6, J (HH) ) 6.6 Hz, 36H,
PCHCH3), -3.29 (t, J (PH) ) 2.8 Hz, 1H, dCH). 31P NMR
(CDCl3, 81.0 MHz): δ 30.5 (s).
P r ep a r a tion of tr a n s-[Ir Cl(dCdCdCP h 2)(P iP r 3)2] (29).
(a) A solution of 28 (50 mg, 0.07 mmol) in 5 mL of ether was
treated with 1 drop of CF3CO2H (ca. 2 µL) and stirred for 15
min at room temperature. A quick change of color from violet
to dark red occurred. The solvent was removed, the residue
was dissolved in 2 mL of toluene/hexane (1:5), and the solution
was chromatographed on Al2O3 (neutral, activity grade V,
height of column 5 cm). With toluene/hexane (1:5) a dark red
fraction was eluted, which was brought to dryness in vacuo.
The residue was dissolved in 3 mL of pentane (50 °C), and
after the solution was cooled to room temperature and then
stored for 12 h at -78 °C dark red crystals precipitated: yield
43 mg (83%).
ν(CtC)coord 1835 cm-1
.
1H NMR (CDCl3, 200 MHz): δ 7.81,
7.20, 7.07 (all m, 5H, C6H5), 2.25 (m, 6H, PCHCH3), 1.23 and
1.03 (both dvt, N ) 13.1, J (HH) ) 6.5 Hz, 18H each, PCHCH3),
0.28 (s, 9H, SiMe3); signal of OH not observed. 13C NMR
(CDCl3, 50.3 MHz): δ 147.2, 127.5, 126.3, 125.2 (all s, C6H5),
100.4 (s, CtCuncoord), 92.9 (t, J (PC) ) 1.1 Hz, CtCcoord), 86.1
(t, J (PC) ) 2.8 Hz, CtCcoord), 71.3, 65.8 (both s, CtCuncoord and
CPh2OH), 22.0 (vt, N ) 23.6 Hz, PCHCH3), 20.0, 19.6 (both s,
PCHCH3), -0.4 (s, SiMe3). 31P NMR (CDCl3, 81.0 MHz): δ
16.0 (s).
(b) A solution of 27 (95 mg, 0.13 mmol) in 10 mL of ether
was treated with 1 drop of CF3CO2H (ca. 2 µL) and stirred for
36 h at room temperature. The solution was then worked up
as described for (a): yield 69 mg (72%).
P r ep a r a t ion of tr a n s-[Ir Cl{dCdC(SiMe3)CtCCP h 2-
OH)}(P iP r 3)2] (33). A sample of 32 (120 mg, 0.14 mmol) was
heated slowly in an NMR tube in vacuo (10-2 Torr) until the
crystals started to melt. We carefully controlled the temper-
ature of the oil bath so that it did not exceed 142 °C. After 10
min the melting process was finished and a red-violet oil was
formed. The oil was dissolved in 1 mL of toluene; the solution
was cooled to -78 °C and then filtered with Al2O3. The filtrate
was brought to dryness in vacuo to give a red-violet oil that
did not crystallize even if it was stored at -78 °C: yield 83
mg (69%). Anal. Calcd for C38H62ClIrOP2Si: C, 53.53; H, 7.33.
Found: C, 53.98; H, 6.86. IR (hexane): ν(OH) 3600, ν(CtC)
(c) A solution of 27 (40 mg, 0.05 mmol) in 0.5 mL of CH2Cl2
was irradiated in an NMR tube for 1 h with a 500 W Hg lamp
(Osram). After the irradiation was stopped, the solution was
worked up as described for (a): yield 26 mg (91%); mp 122 °C
dec. Anal. Calcd for C33H52ClIrP2: C, 53.68; H, 7.10. Found:
C, 53.73; H, 6.89. MS (70 eV): m/z 738 (M+ for 193Ir and 35Cl).
IR (CH2Cl2): ν(CdCdC) 1875 cm-1
.
1H NMR (CDCl3, 200
MHz): δ 7.90, 7.81, 6.95 (all m, 10H, C6H5), 2.91 (m, 6H,
PCHCH3), 1.26 (dvt, N ) 13.5, J (HH) ) 6.4 Hz, 36H,
PCHCH3). 13C NMR (C6D6, 50.3 MHz): δ 249.7 (t, J (PC) )
3.9 Hz, IrdCdCdC), 199.3 (t, J (PC) ) 13.4 Hz, IrdCd), 161.7
(s, ipso-C of C6H5), 138.7 (t, J (PC) ) 2.5 Hz, IrdCdCdC),
129.6, 126.3, 121.1 (all s, C6H5), 22.9 (vt, N ) 26.9 Hz,
PCHCH3), 20.0 (s, PCHCH3). 31P NMR (CDCl3, 81.0 MHz): δ
18.8 (s).
2185, ν(CdC) 1595 cm-1 1H NMR (CDCl3, 200 MHz): δ 7.55,
.
7.24 (both m, 5H, C6H5), 2.86 (m, 6H, PCHCH3), 1.33 (dvt, N
) 13.9, J (HH) ) 6.9 Hz, 36H, PCHCH3), 0.09 (s, 9H, SiMe3);
signal of OH not observed. 13C NMR (CDCl3, 50.3 MHz): δ
252.8 (t, J (PC) ) 11.6 Hz, IrdC), 147.4, 128.1, 127.3, 126.8
(all s, C6H5), 96.0 (t, J (PC) ) 1.1 Hz, CtC), 82.0 (t, J (PC) )
2.4 Hz, IrdCdC), 75.1 (s, CPh2OH), 57.5 (t, J (PC) ) 2.5 Hz,
CtC), 23.4 (vt, N ) 26.6 Hz, PCHCH3), 20.3 (s, PCHCH3), -0.6
(s, SiMe3). 31P NMR (CDCl3, 81.0 MHz): δ 32.9 (s).
Rea ction of 29 w ith CO. A slow stream of CO was passed
through a solution of 29 (50 mg, 0.07 mmol) in 0.5 mL of CDCl3
in an NMR tube. While after 10 s no reaction could be
observed, after 10 min an almost quantitative formation of
trans-[IrCl(CO)(PiPr3)2] (26) took place. Compound 26 was
X-r a y Str u ctu r a l An a lysis of 30. Single crystals were
grown from CDCl3 at room temperature. Crystal data (from
25 reflections, 10° < θ < 12°): orthorhombic, space group Pbca
(No. 61), a ) 11.934(6) Å, b ) 24.777(9) Å, c ) 25.84(2) Å, V )
1
characterized by H and 31P NMR spectroscopy.39
P r ep a r a tion of tr a n s-[Ir Cl(η2-H2CdCdCP h 2)(P iP r 3)2]
(30). A solution of 29 (72 mg, 0.10 mmol) in 5 mL of CH2Cl2
was stirred under
a
H2 atmosphere for 5 min at room
7639(6) Å3, Z ) 8, Dcalcd ) 1.495 g cm-3, µ(Mo KR) ) 4.26 cm-1
,
temperature. A smooth change of color from dark red to yellow
occurred. The solvent was removed, the residue was dissolved
in 3 mL of ether (35 °C), and the solution was stored for 12 h
at -78 °C. Yellow crystals precipitated, which were separated
crystal size 0.50 × 0.35 × 0.30 mm. Solution details: Enraf-
Nonius CAD4 diffractometer, Mo KR radiation (0.709 30 Å),
graphite monochromator, zirconium filter (factor 15.4), T )
293(2) K, ω/θ scan, maximum 2θ ) 45.8°, 5894 reflections

4088 Organometallics, Vol. 16, No. 19, 1997
Werner et al.
measured, 5293 independent reflections, 4083 reflections
regarded as being observed (I > 2σ(I)), 5292 used for refine-
ment; intensity data corrected for Lorentz and polarization
effects, linear decay correction (loss of gain 7.1%) and empirical
absorption correction (ψ-scan method, minimum transmission
50%) applied; structure solved by Patterson method (SHELXS-
86); atomic coordinates and anisotropic thermal parameters
refined by full-matrix least squares against Fo2 (SHELXL-93);
one molecule of probably disordered CDCl3 present in the
asymmetric unit; only one position of the chloro atoms Cl1-
Cl3 could be located and refined anisotropically; positions of
the hydrogen atoms calculated according to ideal geometry and
used only in structure factor calculation; R1 ) 0.0438, wR2 )
0.1018;40 reflection/parameter ratio 14.3; residual electron
Ack n ow led gm en t . We thank the Deutsche For-
schungsgemeinschaft (Grant No. SFB 347) and the
Fonds der Chemischen Industrie for financial support.
We also gratefully acknowledge support by Mrs. R.
Schedl and Mr. C. P. Kneis (elemental analysis and
DTA), Mrs. M. L. Scha¨fer and Dr. W. Buchner (NMR
spectra), Mrs. Dr. G. Lange and Mr. F. Dadrich (mass
spectra), and Degussa AG for various gifts of chemicals.
R.W.L. is particularly grateful for a NATO travel grant.
Su p p or tin g In for m a tion Ava ila ble: Tables of crystal
data and refinement parameters, bond lengths and angles, and
positional and thermal parameters for 30 (6 pages). Ordering
information is given on any current masthead page.
density +1.459/-1.387 e Å-3
.
(40) R1 ) Σ|Fo - Fc|/ΣFo (for Fo > 4σ(Fo)); wR2 ){Σ[w(Fo - Fc2)2]/
2
Σ[w(Fo2)2]}1/2, with w-1 ) σ2(Fo)2 + 0.0405P2 + 86.5 P, where P ) (Fo
2
+ 2Fc2)/3.
OM9703393