Preparation of five- and six-coordinate aryl(hydrido) iridium(III) complexes from benzene and functionalized arenes by C-H activation

Article abstract of DOI:10.1039/b518181j

The reaction of the in situ generated cyclooctene iridium(i) derivative trans-[IrCl(C₈H₁₄)(PiPr₃)₂] with benzene at 80 °C gave a mixture of the five-coordinate dihydrido and hydrido(phenyl) iridium(iii) complexes [IrH₂(Cl)(PiPr ₃)₂] 2 and [IrH(C₆H₅)(Cl)(PiPr ₃)₂] 3 in the ratio of about 1: 2. The chloro- and fluoro-substituted arenes C₆H₅X (X = Cl, F), C ₆H₄F₂ and C₆H₄F(CH ₃) reacted also by C-H activation to afford the corresponding aryl(hydrido) iridium(iii) derivatives [IrH(C₆H₄X)(Cl) (PiPr₃)₂] 7, 8, [IrH(C₆H₃F ₂)(Cl)(PiPr₃)₂] 9-11 and [IrH{C ₆H₃F(CH₃)}(Cl)(PiPr₃)₂] 12, 13, respectively. The formation of isomeric mixtures had been detected by ¹H, ¹³C, ¹⁹F and ³¹P NMR spectroscopy. Treatment of 3 and 7-13 with CO gave the octahedral carbonyl iridium(iii) complexes [IrH(C₆H₃XX′)(Cl)(CO) (PiPr₃)₂] 5, 14-20 without the elimination of the arene. The reactions of trans-[IrCl(C₈H₁₄)(PiPr₃) ₂] with aryl ketones C₆H₅C(O)R (R = Me, Ph), aryl ketoximes C₆H₅C(NOH)R (R = Me, Ph) and benzaloxime C₆H₅C(NOH)H resulted in the formation of six-coordinate aryl(hydrido) iridium(iii) compounds 21-25 with the aryl ligand coordinated in a bidentate κ²-C,O or κ²-C,N fashion. With C₆H₅C(O)NH₂ as the substrate, the two isomers [IrH{κ²-N,O-NHC(O)C₆H₅}(Cl)(PiPr ₃)₂] 26 and [IrH{κ²-C,O-C ₆H₄C(O)NH₂}(Cl)(PiPr₃)₂] 27 were prepared stepwise. Treatment of trans-[IrCl(C₈H ₁₄)(PiPr₃)₂] with benzoic acid gave the benzoato(hydrido) complex [IrH{κ²-O,O-O₂CC ₆H₅}(Cl)(PiPr₃)₂] 29 which did not rearrange to the κ²-C,O isomer. The Royal Society of Chemistry 2006.

Full text of DOI:10.1039/b518181j

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PAPER
www.rsc.org/dalton | Dalton Transactions
Preparation of five- and six-coordinate aryl(hydrido) iridium(III) complexes
from benzene and functionalized arenes by C–H activation†
Helmut Werner,* Arthur Ho¨hn, Michael Dziallas and Thomas Dirnberger
Received 22nd December 2005, Accepted 20th March 2006
First published as an Advance Article on the web 27th March 2006
DOI: 10.1039/b518181j
The reaction of the in situ generated cyclooctene iridium(I) derivative trans-[IrCl(C8H14)(PiPr3)2] with
benzene at 80 ◦C gave a mixture of the five-coordinate dihydrido and hydrido(phenyl) iridium(III)
complexes [IrH2(Cl)(PiPr3)2] 2 and [IrH(C6H5)(Cl)(PiPr3)2] 3 in the ratio of about 1 : 2. The chloro- and
fluoro-substituted arenes C6H5X (X = Cl, F), C6H4F2 and C6H4F(CH3) reacted also by C–H activation
to afford the corresponding aryl(hydrido) iridium(III) derivatives [IrH(C6H4X)(Cl)(PiPr3)2] 7, 8,
[IrH(C6H3F2)(Cl)(PiPr3)2] 9–11 and [IrH{C6H3F(CH3)}(Cl)(PiPr3)2] 12, 13, respectively. The formation
of isomeric mixtures had been detected by 1H, 13C, 19F and 31P NMR spectroscopy. Treatment of 3 and
7–13 with CO gave the octahedral carbonyl iridium(III) complexes [IrH(C6H3XXꢀ)(Cl)(CO)(PiPr3)2] 5,
14–20 without the elimination of the arene. The reactions of trans-[IrCl(C8H14)(PiPr3)2] with aryl
ketones C6H5C(O)R (R = Me, Ph), aryl ketoximes C6H5C(NOH)R (R = Me, Ph) and benzaloxime
C6H5C(NOH)H resulted in the formation of six-coordinate aryl(hydrido) iridium(III) compounds 21–25
with the aryl ligand coordinated in a bidentate j2-C,O or j2-C,N fashion. With C6H5C(O)NH2 as the
substrate, the two isomers [IrH{j2-N,O-NHC(O)C6H5}(Cl)(PiPr3)2] 26 and [IrH{j2-C,O-
C6H4C(O)NH2}(Cl)(PiPr3)2] 27 were prepared stepwise. Treatment of trans-[IrCl(C8H14)(PiPr3)2] with
benzoic acid gave the benzoato(hydrido) complex [IrH{j2-O,O-O2CC6H5}(Cl)(PiPr3)2] 29 which did
not rearrange to the j2-C,O isomer.
Introduction
Results and discussion
In the context of our investigations on the chemistry of four-
and five-coordinate iridium(I) complexes containing [IrCl(PiPr3)2]
as a molecular fragment,1 we found that the labile cyclooctene
Oxidative addition of benzene, chlorobenzene and fluorobenzenes
to an iridium(I) centre
The cyclooctene iridium(I) compound trans-[IrCl(C8H14)(PiPr3)2],
generated in situ from 1 and four equivalents of triisopropy-
lphosphine in benzene,5 reacts at room temperature with HCl
and H2 to give the mono- and dihydrido iridium(III) complexes
[IrH(Cl)2(PiPr3)2] and [IrH2(Cl)(PiPr3)2] 2, respectively.6 Under
the same conditions, no reaction occurs with benzene. However,
if the benzene solution containing the bis(triisopropylphosphine)
cyclooctene derivative is heated for 90 min to 80 ◦C, a mixture
of 2 and 3 is obtained in the ratio of about 1 : 2 (Scheme 1).
The separation of the two products can be achieved by repeated
crystallization from pentane at −78 ◦C. The hydrido(phenyl)
iridium(III) complex 3 forms orange–red crystals, which are
moderately air-sensitive and soluble in most common organic
solvents. Regarding the spectroscopic data of 3, the most typical
iridium(I) derivative trans-[IrCl(C8H14)(PiPr3)2] reacts with vinyl
ꢀ
=
ketones and related Michael systems RCH C(R )C(O)X (X =
H, OMe, NH2, NMe2) at ambient temperature to afford octahe-
dral hydrido(vinyl) iridium(III) compounds with the vinyl ligand
coordinated in a bidentate j2-C,O or j2-C,N fashion.2 With
2
methyl acrylate the corresponding olefin complex trans-[IrCl(g -
=
CH2 CHCO2Me)(PiPr3)2] could be isolated which was converted
at 25 ◦C or above to the thermodynamically more stable irid-
2
=
=
ium(III) isomer [IrH(Cl){j -C,O-CH CHC(OMe) O}(PiPr3)2]
by intramolecular C–H activation.2 In contrast, the ethene deriva-
tive trans-[IrCl(g -C2H4)(PiPr3)2] is thermally rather inert and
2
below its decomposition temperature does not react to give the
3
=
hydrido(vinyl) complex [IrH(Cl)(CH CH2)(PiPr3)2].
Here we report that the in situ generated species trans-
[IrCl(C8H14)(PiPr3)2] can also be used as starting material for
the C–H bond activation of benzene and various functional-
ized arenes. Depending on the substrate, five- or six-coordinate
aryl(hydrido) iridium(III) complexes are formed which even in
the presence of CO do not react by reductive elimination of the
respective arene. A preliminary communication about the very
early results of this work had already appeared.4
1
feature is the Ir–H proton signal at d −32.23 in the H NMR
spectrum, the high-field chemical shift appears to be typical
for hydrido iridium(III) compounds with a five-coordinate metal
centre.6
The proposed stereochemistry of 3 has been confirmed by
an X-ray crystal structure analysis.4 The coordination sphere
is best described as a distorted trigonal bipyramid with the
phosphine ligands in axial positions. The phenyl ring lies exactly
in the trigonal plane. The P–Ir–P axis is somewhat bent (angle
168.1(3)◦) which is probably a consequence of steric repulsion
between the isopropyl groups and the phenyl unit. Particularly
noteworthy is the relatively small angle H–Ir–CPh angle (77.9◦)
Institut fu¨r Anorganische Chemie der Universita¨t Wu¨rzburg, Am Hubland, D-
97074, Wu¨rzburg, Germany. E-mail: helmut.werner@mail.uni-wuerzburg.de
† Dedicated to Professor Ulrich Schubert, with the best of good wishes,
on the occasion of his 60th birthday.
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=
(R = Me, Ph) proceed, in contrast to those with RCH
CHC(O)Me, not by C–H activation of the olefinic substrate but
yield instead the dihydrido compound 2 as the main component.2
The mixture of 2 and 3 formed from 1 and PiPr3 in benzene
smoothly reacts with CO at room temperature to afford the
monocarbonyl complexes 4 and 5 (Scheme 1), which can easily be
separated. Even under slightly increased pressure of CO, neither
elimination of H2 from 4 nor of C6H6 from 5 to give trans-
[IrCl(CO)(PiPr3)2] takes place. Both 4 and 5 are pale yellow
to yellow solids which were characterized by elemental analysis
and mass spectroscopy. The dihydrido(carbonyl) compound 4
was previously generated (although not isolated) from trans-
[IrCl(CO)(PiPr3)2] and dihydrogen and studied with regard to
1
its catalytic properties.15 The H NMR spectrum of 4 displays
two hydride signals at d −8.64 and −20.20 which both appear
as doublet-of-triplets due to 1H–1H and 1H–31P couplings. In
agreement with the data for [IrH2(Cl)(CO)(PMe2Ph)2],16 we as-
sume that the signal with the lower chemical shift should be
assigned to the hydride trans to chloride and that with the
Scheme 1 (L = PiPr3).
1
higher chemical shift to the hydride trans to CO. The H NMR
in the equatorial plane which according to theoretical work by
Jean and Eisenstein7 is traced to a first-order Jahn–Teller effect
and not to an attractive ligand-to-ligand interaction. The so-
called “Y structure” (the name reflecting the position of the three
ligands in the plane of the bipyramid) seems to be generally
favoured when the ligand on the site trans to the acute angle of
about 70–80◦ is both a weak r-donor and a good p-donor such
as chloride, amido, methoxide etc.7 Moreover, the calculations
suggest that the “squeeze” of the regular 120◦ angle R–Ir–
Rꢀ in the plane of distorted trigonal-bipyramidal iridium(III)
complexes of the general composition [IrR(Rꢀ)(X)(L)2] is also
to be expected for R = Rꢀ = alkyl or aryl and R = Rꢀ = H,
which is in agreement with the structural data for [Ir(CH2Ph)2{j3-
P,N,P-N(SiMe2CH2PPh2)2}],8 [Ir(H)2(OCH2CF3)(PCy3)2],9 and
[Ir(H)2(Cl)(PtBu2Ph)2].10 The small angle H–Ir–CPh in compound
3 could also explain the high barrier to rotation about the metal–
phenyl bond in solution, as evidenced by the appearance of six
signals for the C6H5 carbon atoms in the 13C NMR spectrum
of 3 at room temperature. A similar hindered rotation about
metal–phenyl bonds had also been reported for complexes such
as [Ru(C6H4R)(X)(CO)2(L)2], [Ru(C6H4R)(X)(CO)(L)3] (R = H,
Me, Cl, OMe, NMe2; X = Cl, Br, I, OAc; L = PR3, P(OMe)3,
AsR3),11 [(C5Me5)Rh(C6H4R)(X)(PRꢀ3)] (R = H, Me, F, CF3,
OMe, NMe2; X = Cl, Br, I; Rꢀ = Me, Ph, p-Tol)12 and mer-
[IrH(C6H5)(Cl)(PMe3)3],13 although in all of these cases the metal
centre is not five- but six-coordinate and has an 18-electron
configuration.
spectrum of 5 shows the hydride signal at d −7.29 indicating
that in 5, similarly as in 4, a trans H–Ir–CO arrangement exists.
An octahedral iridium(III) complex analogous to 5 with the
composition [IrH(C6H5)(Br)(CO)(PEt3)2] was previously prepared
by Dahlenburg et al. from trans-[IrC6H5(CO)(PEt3)2] and HBr
but in contrast to 5 has the hydrido and the CO ligands in cis
disposition.17 The mixture of 2 and 3a reacts with CO to give 4 and
[IrD(C6D5)(Cl)(CO)(PiPr3)2] 5a, respectively. The two products
were separated due to their different solubility in methanol.
Somewhat unexpectedly, the carbonyl(hydrido)(phenyl) com-
pound 5 was also obtained in excellent yield upon treat-
ment of labile trans-[IrCl(C8H14)(PiPr3)2] with benzaldehyde
(Scheme 2). While the same cyclooctene precursor reacted with
acrolein to give almost exclusively six-coordinate [IrH(Cl)(j2-C,O-
2
=
=
CH CHCH O)(PiPr3)2], in the reaction with benzaldehyde the
formation of an analogous j2-C,O-bonded isomer [IrH(Cl)(j2-
=
C,O-C6H4CH O)(PiPr3)2] could not be observed. We assume
that from trans-[IrCl(C8H14)(PiPr3)2] and C6H5CHO the five-
coordinate intermediate [IrH{C(O)C6H5}(Cl)(PiPr3)2] is initially
formed which by de-insertion of the CO group from the Ir–
C(O)C6H5 unit is transformed to the product. Thermolysis of
5 in refluxing toluene for 6 h affords the Vaska-type com-
plex trans-[IrCl(CO)(PiPr3)2] 6; the concomitant formation of
[IrH(C6H4Me)(Cl)(CO)(PiPr3)2] does not occur. If the thermal
reaction of 5 was carried out in diethylene glycol at 150 ◦C, besides
6 benzene could be detected by GC.
The problem of how the dihydride 2 is formed from 1, PiPr3
and benzene has not been finally solved. The hydrido(phenyl)
complex 3 is definitely not a precursor of 2 since it is recovered
in quantitative yield after heating a benzene solution of 3 for
several hours under reflux. The solvent benzene is also not the
source of the hydride ligands in 2, because from 1, PiPr3 and C6D6 a
mixture of 2 (not [Ir(D)2(Cl)(PiPr3)2]) and [IrD(C6D5)(Cl)(PiPr3)2]
3a is obtained. The most plausible assumption is that cyclooctene
coordinated in precursor 1 functions as the H2-transfer reagent
which would be in agreement with previous work by Crabtree
and others.14 In this context we note that the reactions of in
Scheme 2 (L = PiPr3).
Under similar conditions as used for the preparation of 3, the
in situ generated starting material trans-[IrCl(C8H14)(PiPr3)2] also
=
situ generated trans-[IrCl(C8H14)(PiPr3)2] with RCH CHCO2Me
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reacted with mono- and di-substituted arenes C6H5X (X = Cl, F),
The composition of compounds 7–13 was confirmed by ele-
mental analysis and mass spectra. The 1H NMR spectrum of the
chlorophenyl complex 8 shows two hydride signals at d −35.17
◦
C6H4F2 and C6H4F(CH3) in neat arene at 80 C to afford, apart
from the dihydride 2, the aryl(hydrido) complexes 7–13 in 50–70%
yield of isolated product. In all cases a mixture of isomers was
formed (see Schemes 3 and 4) which mostly could not be separated
by fractional crystallization or column chromatography using de-
activated Al2O3. Only for 11a/11b we succeeded in the separation
of the two isomers by slow crystallization from pentane at −78 ◦C,
though in low yield. While with chlorobenzene, the 1,2-, 1,3- and
1,4-difluorobenzenes and 1,4-C6H4F(CH3) always two isomers
were formed, with C6H5F and 1,2-C6H4F(CH3) as the substrates
besides the main species 7a/7b and 12a/12b a third isomer 7c and
12c could be detected by 1H and 31P NMR spectroscopy. Despite
the lack of precise data we assume that in contrast to 7a/7b
and 12a/12b the minor isomers 7c and 12c contain the fluoro
substituent not in the preferred ortho but in meta or para position
of the phenyl ring. Preliminary kinetic data suggest that the rate of
the reaction of the precursor trans-[IrCl(C8H14)(PiPr3)2] with the
arene increases in the order C6H6 < C6H5F < C6H4F2, which is in
agreement with results by Mawby and co-workers.11 In the same
order, the relative amount of the by-product 2 decreases. Attempts
to prepare the compounds [IrH(C6H4X)(Cl)(PiPr3)2] (X = Br or I)
with bromo- or iodo-benzene as the substrate failed; in these cases
only the dihydrido complex 2 could be isolated.
2
and −34.41 which are split into triplets due to J(P,H) coupling.
Based on the small difference in the chemical shift of these signals,
we assume that in 8a the chloro substituent is in the ortho and in
8b either in the meta or para position of the phenyl ring.
1
The H NMR spectra of 7 and 9–13 also display two hydride
resonances which, however, differ more significantly in their
chemical shift and appear at around d −43 to −44 and −35 to −37.
The signal at higher field is always split into a doublet-of-triplets
indicating that besides the expected 2J(P,H) coupling with the 31
P
4
nuclei of the phosphine ligands an additional J(F,H) coupling
with one fluoride takes place. Therefore, we propose that in the
respective isomers 7a and 9a–13a the fluoro substituent is in the
ortho position of the phenyl group and cis oriented to the Ir–H
bond in the trigonal plane of the molecule. A similar through-
space F–H coupling of the hydride signal had also been observed
1
in the H NMR spectra of [(C5H5)(C5H4C6F5)MH(C6F5)] (M =
Mo, W)18 and [FeH(C6H4F)(dmpe)2] (dmpe = 1,2-C2H4(PMe2)2).19
In these cases the 4J(F,H) coupling constant is 7.4 and 7 Hz and
thus nearly the same as for the isomers 7a and 9a–13a.
The second hydride signal in the spectra of 7 and 9–13 at around
d −35 to −37 shows no F–H coupling and appears as a triplet.
2
Since the J(P,H) coupling constant is identical to that of the
isomers 7a and 9a–13a, we assume that also in 7b and 9b–13b
the fluoro substituent is in the ortho position of the phenyl group
but in contrast to 7a and 9a–13a trans oriented to the Ir–H bond.
The observed hindered rotation around the metal–phenyl bond in
complex 3 supports this proposal.
The 31P NMR spectra of the pairs of isomers 7a/7b, 9a/9b,
10a/10b, 11a/11b, 12a/12b and 13a/13b also display two signals,
the chemical shift of which differs only by 0.8 to 1.2 ppm. Under
off-resonance conditions these signals appear as doublets due to
P–H coupling with the Ir–H proton. The 19F NMR spectra of
7a/7b, 12a/12b and 13a/13b, formed from the monofluoroarenes
C6H5F and C6H4F(CH3), show two resonances while the spectra
of compounds 9a/9b, 10a/10b and 11a/11b, formed from the
difluoroarenes C6H4F2, show four. It is thus obvious that in the
latter pairs of isomers the two fluoro substituents are in different
environments. Based on reference data,18,20 we suggest that the
respective signals at lower field in the spectra of 9a/9b, 10a/10b
and 11a/11b are assigned to the fluoro substituent in ortho position
and those at higher field to the fluoro substituent in meta or para
position. In agreement with the 13C NMR data of 7a/7b, 9a/9b,
11a/11b and 13a/13b (for details see Experimental section) we
conclude that in the reactions of trans-[IrCl(C8H14)(PiPr3)2] with
1,2-C6H4F(X) and 1,3-C6H4F(X) (X = F, CH3) the isomers with
the fluoro substituent in ortho position to the metal-bonded carbon
atom of the phenyl ring are preferentially formed. In neither case
a C–F activation could be observed.
Scheme 3 (L = PiPr3).
Similarly to the hydrido(phenyl) complex 3, the structurally
related compounds 7–13 also react with CO in benzene at room
temperature to give the 1 : 1 adducts 14–20 (Scheme 5). With the
exception of 15, always a mixture of two isomers was formed. In
contrast to 16a/16b–20a/20b, in the case of 14a/14b they had
only been detected by 19F NMR spectroscopy. In the mixtures
of products obtained from 7a/7b and 12a/12b with CO, the
formation of a third isomer had not been observed.
Scheme 4 (L = PiPr3).
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we note that both Caulton and co-workers10 and Jensen and
co-workers21 reported that the monohydrido and the dihydrido
compounds [IrH(Cl)2(PiPr3)2] and [IrH2(Cl)(PiPr3)2] react with
H2 to give the corresponding non-classical dihydrogen complexes
[IrH(Cl)2(H2)(PiPr3)2] and [IrH2(Cl)(H2)(PiPr3)2], which are stable
under a H2 atmosphere. For [IrH(Cl)2(H2)(PiPr3)2], the structure
of the thermodynamically more stable cis isomer (H and H2 cis to
each other) has been confirmed by neutron diffraction.10 It should
also be mentioned that the hydrogenolysis of the metal–aryl bond
in cationic aryl(hydrido) iridium(III) chelate complexes probably
occurs via the formation of Ir(H2) species as intermediates.22
Six-coordinate aryl(hydrido) iridium(III) complexes from aryl
ketones and oximes
The reaction of trans-[IrCl(C8H14)(PiPr3)2] with acetophenone
proceeds under the same conditions as that with benzene. Af-
ter removal of the volatiles and chromatographic work-up the
aryl(hydrido) complex 21 was isolated as a nearly air-stable solid in
=
90% yield (Scheme 7). The IR spectrum of 21 displays the m(C O)
stretching mode at 1580 cm−1, which is shifted by ca. 120 cm−1
to lower wavenumbers compared with the free ketone. Since this
shift is consistent with a coordination of the carbonyl group to
the metal centre, an octahedral geometry for compound 21 can
Scheme 5 (L = PiPr3; R = 3-F (16a, 16b), 4-F (17a, 17b), 5-F (18a, 18b),
3-CH3 (19a,19b), 5-CH3 (20a, 20b); the number indicates the position of
R at the phenyl ring).
1
be assumed. The H NMR spectrum of 21 shows the hydride
1
The H NMR spectra of 14a/14b, 15 and 16a/16b–20a/20b
resonance at d −25.07 as a triplet. The chemical shift is similar
display the hydride signals at d −7.1 to −8.5, which is at signifi-
cantly lower field compared with the five-coordinate compounds
7a/7b–13a/13b. In contrast, the 31P NMR resonances of 14a/14b,
15 and 16a/16b–20a/20b are shifted to higher field compared
with 7a/7b–13a/13b. Since there is only a small difference in the
chemical shift of the hydride signal of 5 and 14–20 and also of
the phosphorus resonances of these compounds, we assume that
the stereochemistry of 14–20 is similar to that of 5. Moreover, it
is conceivable that as in 3 and 7–13 also in 14–20 the rotation
around the metal–aryl bond is severely hindered and that the six-
membered ring lies in the plane of the IrH(Cl)(CO) moiety.
The aryl(hydrido) complexes 3 and 7–13 react with H2 in C6D6
at room temperature very rapidly to afford the dihydride 2 and the
respective arene (Scheme 6). From 3a and H2, compound 2 and
C6D6 are exclusively formed. To rationalize the course of these pro-
cesses, we assume that from [IrH(C6H3RRꢀ)(Cl)(PiPr3)2] and dihy-
drogen a 1 : 1 adduct [IrH(C6H3RRꢀ)(Cl)(H2)(PiPr3)2] is initially
generated which eliminates the arene and gives the coordinatively
unsaturated intermediate [Ir(Cl)(H2)(PiPr3)2]. The latter is finally
converted to 2 by intramolecular oxidative addition. In this context
2
=
=
to that of [IrH(Cl){j -C,O-C(CO2Me) CHC(OMe) O}(PiPr3)2]
which was prepared from trans-[IrCl(C8H14)(PiPr3)2] and dimethyl
fumarate.2 For this complex an octahedral coordination sphere
=
with a trans disposition of the hydride and the C O oxygen
atom was confirmed by an X-ray crystal structure analysis.23 We
note that the five-membered molecular fragment [M]{j2-C,O-
=
C6H4C(Me) O} has also been found for [M] = Mn(CO)4 and
Re(CO)4 as well as for [M] = RuCl(CO)(PPh3)2, respectively.25
24
Scheme 7 (L = PiPr3).
Whereas upon treatment of trans-[IrCl(C8H14)(PiPr3)2] with
acetophenone only minor quantities of the dihydrido compound
2 were formed, the reaction of the same precursor with benzophe-
none led to a 1 : 1 mixture of 2 and the corresponding aryl(hydrido)
complex 22. Both can be separated by column chromatography.
=
The position of the m(C O) band in the IR spectrum and the
chemical shift of the hydride and phosphorus resonances in the
Scheme 6 (L = PiPr3).
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1H and 31P NMR spectra of 21 and 22 are quite similar and thus an
analogous molecular structure for both complexes is most likely.
In contrast to the ketones RC(O)Ph (R = Me, Ph), the
related oximes RC(NOH)Ph react with trans-[IrCl(C8H14)(PiPr3)2]
in toluene even at room temperature. The products23 and 24, being
yellow microcrystalline solids, were isolated in nearly quantitative
yields. The most prominent feature in the IR spectra of 23 and 24
is the m(OH) stretching mode which appears at 3080 cm−1 (for 23)
and 3115 cm−1 (for 24). The 1H NMR spectra of 23 and 24 display
the signal for the OH proton at d 12.19 (for 23) and d 11.06 (for
24) and the hydride signal at d −16.63 (for 23) and d −17.25 (for
24), respectively.
The expected stereochemistry of 23 with the phosphine ligands
and the chloride and the metalated carbon atom of the phenyl
ring in trans disposition was confirmed crystallographically.26 The
2
˚
bond length Ir–C is comparable 2.026(5) A to that in [IrH(Cl){j -
2
˚
=
=
C,O-C(CO2Me) CHC(OMe) O}(PiPr3)2] (2.005(7) A). The Ir–
27
˚
N distance is 2.097(4) A and lies in the region of Ir–N r-bonds.
The P–Ir–P axis (160.4(1)◦) is even more bent than in complex 3
and points in the direction of the smallest (hydride) ligand.
The reaction of trans-[IrCl(C8H14)(PiPr3)2] with benzaloxime
occurs analogously as that with acetophenone and affords the
aryl(hydrido) complex 25 in 83% yield of isolated product. Both
the chemical properties and the most typical IR and NMR data
of 25 are quite similar to those of 23 and deserve no further
comment. It is worth mentioning that in contrast to the five-
coordinate compounds 3 and 7–13 the six-coordinate iridium(III)
complexes 23–25 are inert in the presence of CO and do not react
with dihydrogen under normal conditions.
Scheme 8 (L = PiPr3).
While compound 27 is inert under an atmosphere of CO, the
j2-N,O-bonded isomer 26 reacts rapidly with carbon monoxide
at room temperature to give the expected 1 : 1 adduct 28 (see
=
Scheme 8). Typical for the presence of an un-coordinated C O
group is the absorption at 1615 cm−1 in the IR spectrum, the
position of which being similar to that of free benzoic acidamide.29
The 1H NMR spectrum of 28 displays the hydride resonance at d
−8.78 and thus at a similar chemical shift as for the non-chelate
complexes 14–20.
Hydrido iridium(III) complexes from benzoic acidamide and
benzoic acid
The reaction of trans-[IrCl(C8H14)(PiPr3)2] with benzoic acid
also proceeds at room temperature and affords the chelate
compound 29 in nearly quantitative yield. The composition of
the benzoato(hydrido) complex, which was isolated as a yellow
air-stable solid, was substantiated by elemental analysis and mass
The reaction of trans-[IrCl(C8H14)(PiPr3)2] and benzoic acidamide
in toluene under ultrasound leads to the formation of a yellow
crystalline solid which analyzes as 26 and does not result from
a C–H activation of the phenyl ring. Instead an N–H activation
of the amido group of the acidamide had occurred (Scheme 8).
spectroscopy. While the same iridium(I) precursor reacts with
2
=
acrylic acid to give both [IrH(j -O,O-O2CCH CH2)(Cl)(PiPr3)2]
=
2
2
Diagnostic for 26 are the m(NH) and m(C O) stretching modes
=
and [IrH{j -C,O-CH CHC(OH)O}(Cl)(PiPr3)2], an analogous
product formed by C–H activation was not observed with
benzoic acid as the substrate. Attempts to transform 29 either
thermally or photochemically to the respective isomer [IrH{j2-
in the IR spectrum at, respectively, 3325 and 1525 cm−1 and the
broadened resonance for the NH proton in the 1H NMR spectrum
at d 5.37. The 13C NMR spectrum of 26 displays four signals
for the carbon atoms of the aryl group indicating that a C6H5
and not a C6H4 unit is part of the molecule. In this context we
note that Milstein and co-workers have shown that the coor-
dinatively unsaturated iridium(I) species [IrCl(PEt3)2], generated
from [IrCl(C2H4)(PEt3)2] or [IrCl(PEt3)3] by ligand dissociation,
reacts with aniline by N–H activation to afford the corresponding
iridium(III) complex with [IrH(NHPh)] as a building block.28
If a solution of 26 in benzene is stirred under reflux for 48 h,
a rearrangement takes place and the isomer 27 is obtained in
excellent yield. It is conceivable that under the thermal conditions a
cleavage of the Ir–N bond of 26 occurs and the thermodynamically
preferred product 27 is generated by ortho-metalation of the six-
membered ring. In contrast to 26, the IR spectrum of 27 shows
=
C,O-C6H4C( O)O}(Cl)(PiPr3)2] failed.
Conclusion
The present investigation has shown that the in situ generated
iridium(I) species trans-[IrCl(C8H14)(PiPr3)2], containing a labile
cyclooctene ligand, reacts thermally with benzene and several
substituted benzenes mainly by C–H activation of the arene.
Whereas with C6H6, C6H5Cl, C6H5F and the isomers of C6H4F2
and C6H4F(CH3) as substrates five-coordinate aryl(hydrido) irid-
ium(III) complexes are formed, with aryl ketones, aryl ketoximes
and benzaloxime six-coordinate iridium(III) compounds are ob-
tained. The formation of these products is probably facilitated by
two m(NH) stretching modes at 3280 and 3205 cm−1 as well as a
the coordination of the C O oxygen or the C NOH nitrogen
atom to the metal centre, thus generating a five-membered chelate
system. The so-formed Ir–O or Ir–N linkage is remarkably stable
and remains intact even under a CO atmosphere.
=
=
−1
=
m(C O) band at 1555 cm . Compared with 26 the latter is shifted
by 30 cm−1 to higher frequencies which is in agreement with the
data for 21 and 22, respectively.
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The five-coordinate aryl(hydrido) complexes, in which accord-
ing to NMR studies and theoretical calculations the rotation
around the metal–aryl bond is significantly hindered, react rapidly
both with carbon monoxide and dihydrogen at room temperature.
While with CO very robust 1 : 1 adducts are formed, which
do not rearrange by insertion of CO into the metal–aryl bond,
with H2 elimination of the arene occurs. We assume that also
in this case initially an addition of the substrate to the coor-
dinatively unsaturated metal centre takes place thus generating
an intermediate with a non-classical Ir(H2) unit. The reaction of
trans-[IrCl(C8H14)(PiPr3)2] with benzoic acidamide proceeds by
N–H activation and affords in the initial step an iridium(III) com-
plex with [IrH{j2-N,O-NHC(Ph)O}] as a molecular fragment.
This compound is thermodynamically unstable and smoothly
rearranges to the [IrH{j2-C,O-C6H4C(NH2)O}] isomer. From
trans-[IrCl(C8H14)(PiPr3)2] and benzoic acid the corresponding
benzoato(hydrido) complex is formed which is inert and cannot
be transformed to a ring-metalated isomer.
by comparing the IR and NMR spectroscopic data with those of
an authentic sample:6 yield 72 mg (29%).
[IrD(C6D5)(Cl)(PiPr3)2] 3a. This compound was prepared
analogously as described for 3, from 1 (100 mg, 0.11 mmol) and
PiPr3 (0.10 cm3, 0.50 mmol) in C6D6 (2 cm3). The time of the
reaction was 6 h; the by-product 2 was separated as described
above. 3a is an orange–red microcrystalline solid: yield 80 mg
(56%). MS (70 eV): m/z 632 (M+). IR (KBr): m(CDar) 2190, m(IrD)
1630 cm−1.
[IrH2(Cl)(CO)(PiPr3)2] 4 and [IrH(C6H5)(Cl)(CO)(PiPr3)2] 5.
A slow stream of CO was passed for ca. 10 s through a solution of
a mixture of 2 and 3, generated from 1 (200 mg, 0.22 mmol) and
PiPr3 (0.20 cm3, 1.00 mmol) in pentane (10 cm3). A pale yellow
solid precipitated, which was filtered off and washed three times
with cold methanol (10 cm3, 0 ◦C). The filtrate was concentrated
in vacuo to ca. 2 cm3 and stored for 12 h at −78 ◦C. Pale
yellow, slightly air-sensitive crystals consisting of compound 4
precipitated, which were repeatedly washed with pentane (0◦ C)
and dried. The yellow solid remaining on the fritted disk (being
compound 5) was also washed with pentane (0 ◦C) and dried.
Yield for both 4 and 5 quantitative with respect to the amount of 2
and 3 obtained from 1. Data for 5: mp 187 ◦C (decomp.) (Found:
C, 45.71; H, 7.64. C25H48ClIrOP2 requires C, 45.90; H, 7.40%).
MS (70 eV): m/z 654 (M+), 618 (M+ − HCl). IR (KBr): m(CHar)
3065, m(IrH) 2140, (CO) 1955 cm−1. NMR (C6D6): dH (400 MHz)
7.74, 6.81 (5 H, both m, C6H5), 2.30 (6 H, m, PCHCH3), 1.20, 1.14
[18 H each, dvt, N = 13.9, J(H,H) = 7.0 Hz, PCHCH3], −7.29
[1 H, t, J(P,H) = 17.5 Hz, IrH]; dP (36.2 MHz) 13.4 (s, d in off-
Experimental
All experiments were carried out under an atmosphere of argon
by Schlenk techniques. The starting materials 130 and PiPr3
31
were prepared as described in the literature. NMR spectra were
recorded at room temperature (if not otherwise stated) on Jeol FX
90 Q and Bruker AC 200 and AMX 400 instruments. The NMR
spectra were referenced to TMS (1H and 13C), CFCl3 (19F) and
85% H3PO4 (31P). IR spectra were recorded on a Perkin-Elmer
457 infrared spectrometer, and mass spectra on a Varian MAT
CH 7 instrument. Melting points were measured by differential
thermal analysis (DTA) with a Thermoanalyzer Du Pont 900.
Abbreviations used: s, singlet; d, doublet; t, triplet; vt, virtual
triplet; m, multiplet; br, broadened signal; coupling constants
◦
resonance). Data for 4: mp 185 C (decomp.) (Found: C, 39.22;
H, 7.85. C19H44ClIrOP2 requires C, 39.47; H, 7.67%). MS (70 eV):
m/z 578 (M+), 576 (M+ − H2). IR (KBr): (IrH) 2205, 2100, m(CO)
1965 cm−1. NMR (C6D6): dH (90 MHz) 3.37 (6 H, m, PCHCH3),
1.30, 1.25 [18 H each, dvt, N = 14.0, J(H,H) = 7.1 Hz, PCHCH3],
−8.64 [1 H, dt, J(P,H) = 17.5, J(H,H) = 5.5 Hz, IrH trans to CO],
−20.20 [1 H, dt, J(P,H) = 13.2, J(H,H) = 5.5 Hz, IrH trans to Cl];
dP (36.2 MHz) 32.9 (s, d in off-resonance).
3
5
4
J and N in Hz; N = J(P,H) + J(P,H) or 2J(P,C) + J(P,C).
Preparations
[IrH(C6H5)(Cl)(PiPr3)2] 3. A suspension of 1 (200 mg,
0.22 mmol) in benzene (20 cm3) was treated under stirring with
PiPr3 (0.20 cm3, 1.00 mmol) at room temperature. The yellow
◦
[IrD(C6D5)(Cl)(CO)(PiPr3)2] 5a. This compound was pre-
pared analogously as described for 5, from the mixture of 3a and
2 and CO (2 cm3). The by-product 4 was separated as described
above. 5a is a yellow solid. MS (70 eV): m/z 660 (M+), 623 (M+ −
DCl). IR (KBr): (CDar) 2115, m(CO) 2000, m(IrD) 1530 cm−1.
solution was warmed at 80 C for 2 h and then cooled to room
temperature. After the solvent and the volatiles were evaporated in
vacuo, a red oil remained which was repeatedly recrystallized from
pentane at −78 ◦C. The less soluble fraction (being compound 3)
consisted of orange–red crystals which were separated from ◦the
mother-liquor, washed with small amounts of pentane (−20 C)
and dried: yield 163 mg (58%); mp 112 ◦C (decomp.) (Found: C,
46.01; H, 7.75. C24H48ClIrP2 requires C, 46.03; H, 7.73%). MS
(70 eV): m/z 626 (M+). IR (KBr): m(CHar) 3065, (IrH) 2275 cm−1.
NMR (C6D6): dH (400 MHz) 7.30, 6.83 (5 H, both m, C6H5),
2.53 (6 H, m, PCHCH3), 1.19, 1.06 [18 H each, dvt, N = 13.3,
J(H,H) = 6.9 Hz, PCHCH3], −32.23 [1 H, t, J(P,H) = 12.5 Hz,
IrH]; dC (100.6 MHz) 147.2 (s, d in off-resonance, ipso-C of C6H5),
136.7, 128.9, 124.9, 121.1, 117.7 (all s, d in off-resonance, C6H5),
24.3 (vt, N = 27.8 Hz, PCHCH3), 20.0, 19.6 (both s, PCHCH3);
dP (36.2 MHz) 28.2 (s, d in off-resonance). The mother-liquor was
slowly concentrated in vacuo until yellow crystals of compound
2 precipitated. The crystals were filtered off, washed with small
amounts of pentane (−20 ◦C) and dried. They were characterized
Alternative method for the preparation of compound 5
A suspension of 1 (150 mg, 0.17 mmol) in toluene (5 cm3) was
treated under stirring stepwise with PiPr3 (0.15 cm3, 0.75 mmol)
and benzaldehyde (0.035 cm3, 0.34 mmol). After the mixture was
stirred for 18 h at room temperature, the solvent and the volatiles
were evaporated in vacuo. The oily residue was dissolved in hexane–
toluene (10 : 1, 3 cm3) and the solution chromatographed on Al2O3
(neutral, activity grade V, length of column 6 cm). With hexane–
toluene (10 : 1) a yellow fraction was eluted which was brought
to dryness in vacuo. The remaining yellow microcrystalline solid
was characterized spectroscopically as compound 5. Yield 175 mg
(80%).
2602 | Dalton Trans., 2006, 2597–2606
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Thermal reaction of compound 5
requires C, 43.52; H, 7.00%). MS (70 eV): m/z 662 (M+), 548
(M+ − C6H4F2). NMR (CDCl3): dH (200 MHz) 7.50 −6.95, 6.74
−6.33 (3 H, both br m, C6H3), 2.61 (6 H, m, PCHCH3), 1.22
[36 H, dvt, N = 13.5, J(H,H) = 7.0 Hz, PCHCH3], −43.75 [dt,
J(P,H) = 12.5, J(F,H) = 7.0 Hz, IrH for isomer 9a], −36.58 [t,
J(P,H) = 12.0 Hz, IrH for isomer 9b]; dC (50.3 MHz), data for
9a: 140.9 [d, J(F,C) = 10.5 Hz, C6 of C6H3F2], 124.2 (br s, C5 of
C6H3F2), 108.9 [d, J(F,C) = 13.0 Hz, C4 of C6H3F2], 23.8 (vt, N =
27.4 Hz, PCHCH3), 19.8, 19.5 (both s, PCHCH3), signals for C1,
C2 and C3 of C6H3F2 not exactly located; data for 9b: 132.4 [d,
J(F,C) = 11.1 Hz, C2 of C6H3F2], 120.6 [d, J(F,C) = 7.1 Hz, C3 of
C6H3F2], 109.2 [d, J(F,C) = 13.0 Hz, C4 of C6H3F2], 24.5 (vt, N =
27.1 Hz, PCHCH3), 19.7, 19.2 (both s, PCHCH3), signals for C1,
C5 and C6 of C6H3F2 not exactly located; dP (36.2 MHz) 30.8 (s,
d in off-resonance, for isomer 9a), 31.7 (s, d in off-resonance, for
isomer 9b); dF (84.7 MHz) −51.8, −44.7 (both m, for isomer 9a),
−51.5, −44.3 (both m, for isomer 9b).
A suspension of 5 (51 mg, 0.08 mmol) in diethylene glycol (2 cm3)
was stirred for 90 min at 150 ◦C. After the reaction mixture
was cooled to room temperature, the yellow solution was chro-
matographed on Al2O3 (neutral, activity grade I, length of column
5 cm). With diethylene glycol, a nearly colorless fraction was eluted
which was analyzed by GC. The presence of benzene could be
detected and confirmed by comparing the retention time with that
of an pure sample. Continuing elution with chloroform afforded
a yellow fraction from which 6 was isolated and characterized by
IR and NMR spectroscopy.32 Yield 42 mg (90%).
General procedure for the preparation of compounds
[IrH(C6H3RRꢀ)(Cl)(PiPr3)2] 7–13
A suspension of 1 (200 mg, 0.22 mmol) in toluene (5 cm3) was
treated under stirring with PiPr3 (0.20 cm3, 1.00 mmol) and 2.5 cm3
of the corresponding arene. The yellow solution was warmed at
80 ◦C for 90 min and then cooled to room temperature. After the
solvent and the volatiles were evaporated in vacuo, the oily residue
was dissolved in hexane–toluene (9 : 1, 3 cm3) and the solution
chromatographed on Kieselgel 60. With hexane–benzene (10 : 1)
first a pale yellow fraction containing the dihydrido complex 4 was
eluted. Continuous elution gave an orange or red fraction which
was brought to dryness in vacuo. Recrystallization from pentane
at −78 ◦C gave orange–red to red crystals w◦hich were washed
several times with 2-cm3 portions of pentane (0 C) and dried. For
7, an orange–red oil was obtained.
[IrH(C6H3F2-2,4)(Cl)(PiPr3)2] 10. Yield 210 mg (72%); mp
136 ◦C (decomp.) (Found: C, 43.60; H, 7.40. C24H46ClF2IrP2
requires C, 43.52; H, 7.00%). MS (70 eV): m/z 662 (M+), 548
(M+ − C6H4F2). NMR (C6D6): dH (90 MHz) 7.22–6.92, 6.63–6.22
(3 H, both br m, C6H3), 2.51 (6 H, m, PCHCH3), 1.16 (36 H, m,
PCHCH3), −43.20 [dt, J(P,H) = 13.0, J(F,H) = 6.7 Hz, IrH for
isomer 10a], −36.03 [t, J(P,H) = 13.0 Hz, IrH for isomer 10b]; dP
(36.2 MHz) 30.9 (s, d in off-resonance, for isomer 10a), 30.0 (s,
d in off-resonance, for isomer 10b); dF (84.7 MHz) −56.3, −19.6
(both m, for isomer 10a), −49.8, −19.5 (both m, for isomer 10b).
[IrH(C6H3F2-2,5)(Cl)(PiPr3)2] 11. Yield 184 mg (62%); mp
117 ◦C (decomp.) (Found: C, 43.20; H, 7.31. C24H46ClF2IrP2
requires C, 43.52; H, 7.00%). MS (70 eV): m/z 662 (M+), 548
(M+ − C6H4F2). NMR (CDCl3): dH (200 MHz) 7.55–7.23, 6.86–
6.33 (3 H, both br m, C6H3), 2.59 (6 H, m, PCHCH3), 1.23
[36 H, dvt, N = 13.5, J(H,H) = 7.0 Hz, PCHCH3], −43.83 [dt,
J(P,H) = 12.5, J(F,H) = 8.0 Hz, IrH for isomer 11a], −36.92 [t,
J(P,H) = 12.0 Hz, IrH for isomer 11b]; dC (50.3 MHz), data for
[IrH(C6H4F)(Cl)(PiPr3)2] 7. MS (70 eV): m/z 644 (M+), 548
(M+ − C6H5F). NMR (CDCl3): dH (200 MHz) 7.65, 6.97–6.38
(4 H, br m, C6H4), 2.51 (6 H, m, PCHCH3), 1.18 (36 H, m,
PCHCH3), −43.46 [dt, J(P,H) = 12.2, J(F,H) = 6.7 Hz, IrH for
isomer 7a], −35.92 [t, J(P,H) = 12.2 Hz, IrH for isomer 7b], −35.08
[t, J(P,H) = 12.2 Hz, IrH for isomer 7c]; dC (50.3 MHz), data for
7a: 166.0 [d, J(F,C) = 219.1 Hz, C2F of C6H4F], 145.8 [d, J(F,C) =
12.0 Hz, C6 of C6H4F], 124.1 (s, C5 of C6H4F), 121.8 [d, J(F,C) =
7.9 Hz, C4 of C6H4F], 112.3 [d, J(F,C) = 27.2 Hz, C3 of C6H4F],
23.5 (vt, N = 27.1 Hz, PCHCH3), 19.6, 19.4 (both s, PCHCH3),
signal for C1 of C6H4F not exactly located; data for 7b: 166.5 [d,
J(F,C) = 229.6 Hz, C6F of C6H4F], 137.5 [d, J(F,C) = 12.7 Hz,
C2 of C6H4F], 122.1 [d, J(F,C) = 7.9 Hz, C4 of C6H4F], 120.7 (s,
C3 of C6H4F), 113.2 [d, J(F,C) = 30.0 Hz, C5 of C6H4F], 24.2 (vt,
N = 26.2 Hz, PCHCH3), 19.5, 19.3 (both s, PCHCH3), signal for
C1 of C6H4F not exactly located; dP (36.2 MHz) 30.6 (s, d in off-
resonance, for isomer 7a), 31.7 (s, d in off-resonance, for isomer
7b), 29.9 (s, d in off-resonance, for isomer 7c); dF (84.7 MHz) −26.0
(m, for isomer 7a), −18.9 (m, for isomer 7b).
[IrH(C6H4Cl)(Cl)(PiPr3)2] 8. Yield 146 mg (50%); mp 103 ◦C
(decomp.) (Found: C, 43.19; H, 7.45. C24H47Cl2IrP2 requires C,
43.63; H, 7.17%). MS (70 eV): m/z 660 (M+), 548 (M+ − C6H5Cl).
NMR (CDCl3): dH (90 MHz) 7.39, 6.83 −6.33 (4 H, br m, C6H4),
2.64 (6 H, m, PCHCH3), 1.29 [36 H, dvt, N = 13.5, J(H,H) =
6.0 Hz, PCHCH3], −35.17 [t, J(P,H) = 12.5 Hz, IrH for isomer
8a], −34.41 [t, J(P,H) = 13.0 Hz, IrH for isomer 8b]; dP (36.2 MHz)
30.0 (s, d in off-resonance).
1
5
11a: 162.5 [dd, J(F,C) = 214.2, J(F,C) = 3 Hz, C2 of C6H3F2],
159.0 [dd, 1J(F,C) = 241.1, 5J(F,C) = 3 Hz, C5 of C6H3F2], 131.1
[dd, 2J(F,C) = 20.1, 3J(F,C) = 12.8 Hz, C4 of C6H3F2], 115.0 [ddt,
3
2J(F,C) = 41.2, J(F,C) = 5.5, J(P,C) = 7.3 Hz, C1 of C6H3F2],
112.2 [dd, 2J(F,C) = 30.5, 3J(F,C) = 9.2 Hz, C6 of C6H3F2], 107.5
2
3
[dd, J(F,C) = 24.4, J(F,C) = 9.5 Hz, C3 of C6H3F2], 23.6 (vt,
N = 26.9 Hz, PCHCH3), 19.6, 19.1 (both s, PCHCH3); data for
11b: 163.6 [dd, J(F,C) = 215.0, J(F,C) = 3 Hz, C6 of C6H3F2],
155.8 [dd, 1J(F,C) = 241.0, 5J(F,C) = 3 Hz, C3 of C6H3F2], 131.1
[dd, 2J(F,C) = 20.1, 3J(F,C) = 12.8 Hz, C4 of C6H3F2], 113.4 [dd,
1
5
2J(F,C) = 33.6, J(F,C) = 9.7 Hz, C2 of C6H3F2], 112 (m, C1 of
3
C6H3F2), 107.9 [dd, J(F,C) = 24.4, J(F,C) = 10.4 Hz, C5 of
C6H3F2], 24.3 (vt, N = 28.1 Hz, PCHCH3), 19.4, 19.0 (both s,
PCHCH3); dP (36.2 MHz) 31.7 (s, d in off-resonance, for isomer
11a), 30.9 (s, d in off-resonance, for isomer 11b); dF (84.7 MHz)
−53.4, −33.7 (both m, for isomer 11a), −51.8, −24.9 (both m, for
isomer 11b).
2
3
[IrH(C6H3F(CH3)-2,3)(Cl)(PiPr3)2] 12. Yield 182 mg (63%);
◦
mp 115 C (decomp.). MS (70 eV): m/z 658 (M+), 548 (M+
−
C7H7F). NMR (C6D6): dH (90 MHz) 7.15–6.58 (3 H, br m, C6H3),
2.55 (6 H, m, PCHCH3), 2.21 (3 H, s, C6H3CH3), 1.16 (36 H,
m, PCHCH3), −42.92 [dt, J(P,H) = 13.2, J(F,H) = 8.8 Hz, IrH
[IrH(C6H3F2-2,3)(Cl)(PiPr3)2] 9. Yield 204 mg (70%); mp
121 ◦C (decomp.) (Found: C, 43.70; H, 7.37. C24H46ClF2IrP2
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for isomer 12a], −35.22 [t, J(P,H) = 13.2 Hz, IrH for isomer
12b], −33.41 [t, J(P,H) = 13.2 Hz, IrH for isomer 12c]; dP (36.2
MHz) 30.8 (s, d in off-resonance, for isomer 12a), 29.8 (s, d in off-
resonance, for isomer 12b), 29.3 (s, d in off-resonance, for isomer
12c); dF (84.7 MHz) −49.8 (m, for isomer 12a), −41.3 (m, for
isomer 12b).
m, C6H4), 2.39 (6 H, m, PCHCH3), 1.33 [36 H, dvt, N = 22.0,
J(H,H) = 6.0 Hz, PCHCH3], −7.63 [t, J(P,H) = 17.6 Hz, IrH]; dP
(36.2 MHz) 13.9 (s, d in off-resonance).
[IrH(C6H3F2-2,3)(Cl)(CO)(PiPr3)2] 16. Yield 104 mg (75%);
◦
mp 230 C (Found: C, 43.01; H, 7.12. C25H46ClF2IrOP2 requires
C, 43.40; H, 6.71%). MS (70 eV): m/z 690 (M+), 654 (M+ − HCl),
576 (M+ − C6H4F2). IR (KBr): m(IrH) 2140, m(CO) 2000 cm−1.
NMR (C6D6): dH (90 MHz) 7.24–7.03, 6.52–6.21 (3 H, both br
m, C6H3), 2.34 (6 H, m, PCHCH3), 1.32 [36 H, dvt, N = 18.5,
J(H,H) = 6.0 Hz, PCHCH3], −8.27 [dt, J(P,H) = 18.0, J(F,H) =
2.9 Hz, IrH for isomer 16a], −7.41 [t, J(P,H) = 17.0 Hz, IrH for
isomer 16b]; dP (36.2 MHz) 12.0 (s, d in off-resonance); dF (84.7
MHz) −40.1, −3.1 (both m, for isomer 16a), −36.2, −2.6 (both
m, for isomer 16b).
[IrH(C6H3F(CH3)-2,5)(Cl)(PiPr3)2] 13. Yield 174 mg (60%);
◦
mp 118 C (decomp.) (Found: C, 45.73; H, 7.83. C25H49ClFIrP2
requires C, 45.61; H, 7.50%). MS (70 eV): m/z 658 (M+), 548
(M+ − C7H7F). NMR (CDCl3): dH (90 MHz) 7.26–7.06, 6.67–
6.57 (3 H, both br m, C6H3), 2.50 (6 H, m, PCHCH3), 2.18 (3 H,
br s, C6H3CH3), 1.18 (36 H, m, PCHCH3), −43.08 [dt, J(P,H) =
13.0, J(F,H) = 7.5 Hz, IrH for isomer 13a], −34.92 [t, J(P,H) =
13.0 Hz, IrH for isomer 13b]; dC (50.3 MHz), data for 13a: 166.5
1
3
[d, J(F,C) = 246.5 Hz, C2 of C6H3F(CH3)], 146.8 [d, J(F,C) =
12.2 Hz, C6 of C6H3F(CH3)], 132.6 [s, C5 of C6H3F(CH3)], 122.6
[IrH(C6H3F2-2,4)(Cl)(CO)(PiPr3)2] 17. Yield98mg (71%); mp
189 ◦C (Found: C, 44.06; H, 7.04. C25H46ClF2IrOP2 requires C,
43.40; H, 6.71%). MS (70 eV): m/z 690 (M+), 654 (M+ − HCl),
576 (M+ − C6H4F2). IR (KBr): m(IrH) 2140, (CO) 2000 cm−1.
NMR (C6D6): dH (90 MHz) 7.82–7.43, 6.52–6.18 (3 H, both br m,
C6H3), 2.23 (6 H, m, PCHCH3), 1.15 (36 H, m, PCHCH3), −8.09
[dt, J(P,H) = 17.6, J(F,H) = 2.9 Hz, IrH for isomer 17a], −7.48 [t,
J(P,H) = 16.1 Hz, IrH for isomer 17b]; dP (36.2 MHz) 11.8 (s, d in
off-resonance); dF (84.7 MHz) −72.1, −27.3 (both m, for isomer
17a), −67.7, −22.0 (both m, for isomer 17b).
3
2
[d, J(F,C) = 8.5 Hz, C4 of C6H3F(CH3)], 112.9 [d, J(F,C) =
23.2 Hz, C3 of C6H3F(CH3)], 107.3 [d, J(F,C) = 33.5 Hz, C1
2
of C6H3F(CH3)], 23.7 (vt, N = 26.8 Hz, PCHCH3), 20.5 [d,
5J(F,C) = 3.0 Hz, C6H3CH3], 19.8, 19.2 (both s, PCHCH3);
data for 13b: 165.8 [d, J(F,C) = 234.2 Hz, C6 of C6H3F(CH3)],
1
137.9 [d, J(F,C) = 12.8 Hz, C2 of C6H3F(CH3)], 129.4 [s, C3 of
3
C6H3F(CH3)], 122.3 [d, J(F,C) = 9.2 Hz, C4 of C6H3F(CH3)],
3
111.6 [dt, J(F,C) = 31.9, J(P,C) = 7.9 Hz, C1 of C6H3F(CH3)],
2
2
111.5 [d, J(F,C) = 20.1 Hz, C5 of C6H3F(CH3)], 24.3 (vt, N =
2
5
26.8 Hz, PCHCH3), 20.5 [d, J(F,C) = 3.0 Hz, C6H3CH3], 19.6,
[IrH(C6H3F2-2,5)(Cl)(CO)(PiPr3)2] 18. Yield 110 mg (80%);
19.1 (both s, PCHCH3); dP (36.2 MHz) 31.1 (s, d in off-resonance,
for isomer 13a), 29.9 (s, d in off-resonance, for isomer 13b); dF
(84.7 MHz) −47.1 (m, for isomer 13a), −41.4 (m, for isomer 13b).
◦
mp 178 C (Found: C, 43.48; H, 6.93. C25H46ClF2IrOP2 requires
C, 43.40; H, 6.71%). MS (70 eV): m/z 690 (M+), 654 (M+ − HCl),
576 (M+ − C6H4F2). IR (KBr): m(IrH) 2140, (CO) 2005 cm−1.
NMR (C6D6): dH (90 MHz) 7.50–6.95, 6.73–6.27 (3 H, both br m,
C6H3), 2.37 (6 H, m, PCHCH3), 1.28 (36 H, PCHCH3), −8.30 [dt,
J(P,H) = 17.2, J(F,H) = 2.0 Hz, IrH for isomer 18a], −7.65 [t,
J(P,H) = 16.0 Hz, IrH for isomer 18b]; dP (36.2 MHz) 13.0 (s, d in
off-resonance); dF (84.7 MHz) −53.9, −33.4 (both m).
General procedure for the preparation of compounds
[IrH(C6H3RRꢀ)(Cl)(CO)(PiPr3)2] 14–20
A slow stream of CO was passed for 10 s through the solution
generated from 1 (90 mg, 0.10 mmol), PiPr3 (0.10 cm3, 0.50 mmol)
and 1.2 cm3 of C6H4RRꢀ in toluene (5 cm3). The yellow solution
was warmed at 80 ◦C for 90 min and then cooled to room
temperature. After the reaction mixture was stirred for 5 min, the
solvent and the volatiles were evaporated in vacuo and methanol
(3 cm3) was added to the residue. A suspension containing a
pale yellow solid was obtained. The solid was filtered off, washed
[IrH(C6H3F(CH3)-2,3)(Cl)(CO)(PiPr3)2] 19. Yield 94 mg
(69%); mp 187 ◦C (Found: C, 45.61; H, 7.42. C26H49ClFIrOP2
requires C, 45.50; H, 7.19%). MS (70 eV): m/z 686 (M+), 650
(M+ − HCl), 576 (M+ − C7H7F). IR (KBr): m(IrH) 2130, (CO)
2000, 1985 cm−1. NMR (C6D6): dH (90 MHz) 7.65–7.25, 6.70–
6.30 (3 H, both br m, C6H3), 2.28 (6 H, m, PCHCH3), 2.18
(3 H, s, C6H3CH3), 1.15 [36 H, dvt, N = 16.1, J(H,H) = 7.3 Hz,
PCHCH3], −8.22 [t, J(P,H) = 19.1 Hz, IrH for isomer 19a], −7.35
[t, J(P,H) = 17.6 Hz, IrH for isomer 19b]; dP (36.2 MHz) 12.0 (s, d
in off-resonance); dF (84.7 MHz) −65.0 (m, for isomer 19a), −61.3
(m, for isomer 19b).
◦
three times with small amounts of methanol (0 C) and dried in
vacuo. The filtrate contained the dihydrido complex 4 which is
readily soluble in methanol.
[IrH(C6H4F)(Cl)(CO)(PiPr3)2] 14. Yield 94 mg (70%); mp
177 ◦C (Found: C, 44.92; H, 7.36. C25H47ClFIrOP2 requires C,
44.67; H, 7.05%). MS (70 eV): m/z 672 (M+), 636 (M+ − HCl),
576 (M+ − C6H5F). IR (KBr): m(IrH) 2275, (CO) 1985 cm−1. NMR
(C6D6): dH (200 MHz) 7.57, 6.75, 6.64, 6.45 (4 H, all m, C6H4),
2.32 (6 H, m, PCHCH3), 1.25 (36 H, m, PCHCH3), −8.11 [dt,
J(P,H) = 17.7, J(F,H) = 2.6 Hz, IrH]; dP (36.2 MHz) 13.0 (s, d in
off-resonance); dF (84.7 MHz) −8.1 (m, for isomer 14a), −4.1 (m,
for isomer 14b).
[IrH(C6H3F(CH3)-2,5)(Cl)(CO)(PiPr3)2] 20. Yield 104 mg
(75%); mp 188 ◦C (Found: C, 45.91; H, 7.54. C26H49ClFIrOP2
requires C, 45.50; H, 7.19%). MS (70 eV): m/z 686 (M+), 650
(M+ − HCl), 576 (M+ − C7H7F). IR (KBr): m(IrH) 2125, (CO)
2000, 1990 cm−1. NMR (C6D6): dH (90 MHz) 7.45–7.20, 6.95–
6.30 (3 H, both br m, C6H3), 2.33 (6 H, m, PCHCH3), 2.11
(3 H, s, C6H3CH3), 1.25, 1.17 [36 H, both dvt, N = 14,7, J(H,H) =
7.3 Hz, PCHCH3], −7.96 [dt, J(P,H) = 17.6, J(F,H) = 2.9 Hz, IrH
for isomer 20a], −7.11 [t, J(P,H) = 17.6 Hz, IrH for isomer 20b];
dP (36.2 MHz) 12.1 (s, d in off-resonance, for isomer 20a), 12.3 (s,
d in off-resonance, for isomer 20b); dF (84.7 MHz) −62.4 (m, for
isomer 20a), −58.3 (m, for isomer 20b).
[IrH(C6H4Cl)(Cl)(CO)(PiPr3)2] 15. Yield 82 mg (60%); mp
193 ◦C (Found: C, 43.45; H, 6.80. C25H47Cl2IrOP2 requires C,
43.60; H, 6.88%). MS (70 eV): m/z 688 (M+), 652 (M+ − HCl),
576 (M+ − C6H5Cl). IR (KBr): m(IrH) 2120, m(CO) 1980 cm−1.
NMR (C6D6): dH (90 MHz) 7.65–7.17, 6.87–6.56 (4 H, both br
2604 | Dalton Trans., 2006, 2597–2606
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[IrH{j2-C,O-C6H4C(O)Me}(Cl)(PiPr3)2] 21. This compound
was prepared analogously as described for 3, from 1 (150 mg,
0.17 mmol) and PiPr3 (0.15 cm3, 0.75 mmol) in acetophenone
(3 cm3, 24.0 mmol). The oily residue, obtained after evaporation
of the volatiles, was dissolved in hexane–benzene (15 : 1, 3 cm3)
and the solution chromatographed on Al2O3 (neutral, activity
grade V, length of column 6 cm). With hexane–benzene (15 : 1)
an orange fraction was eluted which was brought to dryness in
vacuo. The remaining orange microcrystalline solid was washed
several times with 3-cm3 portions of hexane (0 ◦C) and dried: yield
−16.63 [1 H, t, J(P,H) = 18.4 Hz, IrH]; dP (36.2 MHz) 8.6 (s, d in
off-resonance).
[IrH{j2-C,N–C6H4C(NOH)Me}(Cl)(PiPr3)2] 24. This com-
pound was prepared analogously as described for 23, from 1
(200 mg, 0.22 mmol), PiPr3 (0.20 cm3, 1.00 mmol) and ace-
tophenone oxime (60 mg, 0.44 mmol) in toluene (5 cm3). A light
yellow microcrystalline solid was obtained: yield 274 mg (90%);
◦
mp 222 C (Found: C, 46.08; H, 7.84, N, 2.00. C26H51ClIrNOP2
requires C, 45.70; H, 7.52, N, 2.05%). MS (70 eV): m/z 683 (M+),
548 (M+ − PhC(NOH)Me), 523 (M+ − PiPr3). IR (KBr): m(OH)
3115, (IrH) 2185 cm−1. NMR (CDCl3): dH (200 MHz) 11.06 (1 H, s,
OH), 7.19, 6.97, 6.72 (4 H, all m, C6H4), 2.33 (3 H, t, J(P,H) =
1.4 Hz, C(NOH)CH3), 2.29(6 H, m, PCHCH3), 1.19, 0.85 [18 H
each, dvt, N = 13.3, J(H,H) = 7.0 Hz, PCHCH3], −17.25 [1 H,
t, J(P,H) = 18.0 Hz, IrH]; dC (50.3 MHz) 161.6 (s, C(NOH)CH3),
142.4 (t, J(P,C) = 6.7 Hz, ipso-C of C6H4), 142.7, 138.7, 128.6,
124.4, 119.6 (all s, C6H4), 23.7 (vt, N = 27.2 Hz, PCHCH3), 18.9,
18.6 (both s, PCHCH3), 11.4 (s, C6H4CH3); dP (36.2 MHz) 8.6 (s,
d in off-resonance).
◦
201 mg (90%); mp 180 C (decomp.) (Found: C, 46.26; H, 7.77.
C26H50ClIrOP2 requires C, 46.72; H, 7.54%). MS (70 eV): m/z 668
(M+), 548 (M+ − PhC(O)Me). IR (KBr): m(IrH) 2235, m(C O)
=
1580 cm−1. NMR (CDCl3): dH (90 MHz) 7.79, 7.26, 6.77 (4 H,
all m, C6H4), 2.40 (6 H, m, PCHCH3), 2.38 (3 H, s, C6H4CH3),
1.23, 0.99 [18 H each, dvt, N = 13.2, J(H,H) = 7.2 Hz, PCHCH3],
−25.07 [1 H, t, J(P,H) = 16.2 Hz, IrH]; dC (50.3 MHz) 211.9 (s,
C(O)CH3), 162.8 (t, J(P,C) = 6.6 Hz, ipso-C of C6H4), 145.1, 141.5,
133.5, 130.8, 118.9 (all s, C6H4), 24.2 (s, C6H4CH3), 23.5 (vt, N =
27.1 Hz, PCHCH3), 19.3, 18.6 (both s, PCHCH3); dP (36.2 MHz)
12.0 (s, d in off-resonance).
[IrH{j2-C,N-C6H4C(NOH)H}(Cl)(PiPr3)2] 25. This com-
pound was prepared analogously as described for 23, from 1
(200 mg, 0.22 mmol), PiPr3 (0.20 cm3, 1.00 mmol) and benzaloxime
(53 mg, 0.44 mmol) in toluene (5 cm3). A light yellow micro-
crystalline solid was obtained: yield 248 mg (83%); mp 167 ◦C
(decomp.) (Found: C, 44.91; H, 7.54, N, 2.39. C25H49ClIrNOP2
requires C, 44.87; H, 7.38, N, 2.10%). MS (70 eV): m/z 669 (M+),
548 (M+ − PhC(NOH)H), 509 (M+ − PiPr3). IR (KBr): m(OH)
3140, (IrH) 2180 cm−1. NMR (C6D6): dH (90 MHz) 11.89 (1 H, s,
OH), 7.91 (1 H, br s, C(NOH)H), 7.49, 6.90 (4 H, both m, C6H4),
2.47 (6 H, m, PCHCH3), 1.24, 0.92 [18 H each, dvt, N = 13.2,
J(H,H) = 7.2 Hz, PCHCH3], −17.11 [1 H, t, J(P,H) = 18.1 Hz,
IrH]; dP (36.2 MHz) 8.7 (s, d in off-resonance).
[IrH{j2-C,O-C6H4C(O)Ph}(Cl)(PiPr3)2] 22. This compound
was prepared analogously as described for 3, from 1 (200 mg,
0.22 mmol), PiPr3 (0.20 cm3, 1.00 mmol) and benzophenone
(450 mg, 2.50 mmol) in toluene (3 cm3). The oily residue, obtained
after evaporation of the volatiles, was dissolved in hexane–toluene
(10 : 1, 3 cm3) and the solution chromatographed on Al2O3
(neutral, activity grade V, length of column 6 cm). With hexane–
toluene (10 : 1) first a yellow fraction was eluted which contained
the dihydride 2 (49 mg, 20%). Continuing elution gave an orange
fraction which was brought to dryness in vacuo. The remaining
orange microcrystalline solid was washed several times with 3-
cm3 portions of hexane (0 ◦C) and dried: yield 65 mg (20%);
[IrH{j2-N,O-NHC(O)Ph}(Cl)(PiPr3)2] 26. A suspension of
1 (180 mg, 0.20 mmol) in toluene (10 cm3) was treated with
PiPr3 (0.18 cm3, 0.90 mmol) and benzoic acidamide (48 mg,
0.40 mmol) and irradiated in an ultrasonic bath for 30 min at room
temperature. A yellow solid precipitated which was separated from
the mother-liquor and recrystallized from hexane–CH2Cl2 (5 :
◦
mp 211 C (decomp.) (Found: C, 51.57; H, 7.68. C31H52ClIrOP2
requires C, 50.98; H, 7.18%). MS (70 eV): m/z 730 (M+), 548 (M+ −
−1
=
PhC(O)Ph). IR (KBr): m(IrH) 2270, m(C O) 1545 cm . NMR
(C6D6): dH (90 MHz) 7.98–6.59 (9 H, br m, C6H4 and C6H5), 2.46
(6 H, m, PCHCH3), 1.24, 1.03 [18 H each, dvt, N = 13.9, J(H,H) =
7.4 Hz, PCHCH3], −24.34 [1 H, t, J(P,H) = 16.0 Hz, IrH]; dP (36.2
MHz) 12.3 (s, d in off-resonance).
◦
1): yield 241 mg (90%); mp 181 C (decomp.) (Found: C, 44.52;
H, 7.75, N, 1.99. C25H49ClIrNOP2 requires C, 44.87; H, 7.38, N,
2.10%). MS (70 eV): m/z 669 (M+), 548 (M+ − PhC(O)NH2). IR
[IrH{j2-C,N–C6H4C(NOH)Ph}(Cl)(PiPr3)2] 23. A suspen-
sion of 1 (200 mg, 0.22 mmol) in toluene (5 cm3) was treated under
stirring with PiPr3 (0.20 cm3, 1.00 mmol) at room temperature. An
orange solution was formed to which benzophenoneoxime (85 mg,
0.44 mmol) was added. The reaction mixture was stirred for 30 min
at room temperature and the volatiles were evaporated in vacuo.
The oily residue was layered with pentane (1 cm3) and the solution
stored for 6 h. Light yellow crystals precipitated which were
separated from the mother-liquor, washed with small amounts
−1
=
(KBr): m(NH) 3325, (IrH) 2270, (C O) 1525 cm . NMR (CDCl3):
dH (90 MHz) 7.78–7.51 (5 H, br m, C6H5), 5.37 (1 H, br s, NH), 2.87
(6 H, m, PCHCH3), 1.55, 1.51 [18 H each, dvt, N = 13.2, J(H,H) =
7.0 Hz, PCHCH3], −31.54 [1 H, t, J(P,H) = 13.4 Hz, IrH]; dC (50.3
MHz) 176.9 (s, C(O)NH), 137.6 (s, ipso-C of C6H5), 129.6, 128.4,
125.7 (all s, C6H5), 22.5 (vt, N = 25.8 Hz, PCHCH3), 19.0, 18.8
(both s, PCHCH3); dP (36.2 MHz) 13.6 (s, d in off-resonance).
[IrH{j2-C,O-C6H4C(O)NH2}(Cl)(PiPr3)2] 27. A suspension
of 26 (160 mg, 0.24 mmol) in benzene (5 cm3) was stirred for 48 h
under reflux. After the solution was cooled to room temperature,
the solvent was evaporated in vacuo. The residue was recrystallized
from hexane–CH2Cl2 (5 : 1) to give a light yellow microcrystalline
solid: yield 136 mg (85%); mp 219 ◦C (decomp.) (Found: C,
44.94; H, 7.31, N, 2.39. C25H49ClIrNOP2 requires C, 44.87; H,
◦
◦
of pentane (−20 C) and dried: yield 296 mg (89%); mp 209 C
(Found: C, 50.20; H, 7.39, N, 1.87. C31H53ClIrNOP2 requires C,
49.95; H, 7.17, N, 1.88%). MS (70 eV): m/z 745 (M+), 585 (M+ −
PiPr3), 548 (M+ − PhC(NOH)Ph). IR (KBr): (OH) 3080, (IrH)
2195 cm−1. NMR (C6D6): dH (90 MHz) 12.19 (1 H, s, OH), 7.75–
6.71 (9 H, br m, C6H4 and C6H5), 2.52 (6 H, m, PCHCH3), 1.27,
1.00 [18 H each, dvt, N = 13.2, J(H,H) = 7.3 Hz, PCHCH3],
=
7.38, N, 2.10%). IR (KBr): (NH) 3280, 3205, m(IrH) 2250, m(C O)
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1555 cm−1. NMR (CD2Cl2): dH (90 MHz) 7.48–6.76 (4 H, br m,
C6H4), 2.33 (6 H, m, PCHCH3), 1.59 (1 H, br s, NH), 1.21, 1.01 [18
H each, dvt, N = 13.2, J(H,H) = 7.1 Hz, PCHCH3], −26.32 [1 H, t,
J(P,H) = 16.2 Hz, IrH]; dP (36.2 MHz) 11.7 (s, d in off-resonance).
2 T. Dirnberger and H. Werner, Organometallics, 2005, 24, 5127.
3 M. Schulz and H. Werner, Organometallics, 1992, 11, 2790.
4 H. Werner, A. Ho¨hn and M. Dziallas, Angew. Chem., Int. Ed. Engl.,
1986, 25, 1315.
5 M. Schulz, Diploma Thesis, Universitat Wurzburg, 1988.
6 H. Werner, J. Wolf and A. Ho¨hn, J. Organomet. Chem., 1985, 287, 395.
7 Y. Jean and O. Eisenstein, Polyhedron, 1988, 7, 405; J.-F. Riehl, Y. Jean,
O. Eisenstein and M. Pe´lissier, Organometallics, 1992, 11, 729.
8 M. D. Fryzuk, P. A. MacNeil, R. L. Massey and R. G. Ball,
J. Organomet. Chem., 1989, 328, 231.
¨
¨
[IrH{j1-NHC(O)Ph}(Cl)(CO)(PiPr3)2] 28. A slow stream of
CO was passed for ca. 2 min through a solution of 26 (95 mg,
0.14 mmol) in CHCl3 (5 cm3) at room temperature. The solvent
was evaporated in vacuo and the residue recrystallized from
hexane–CH2Cl2 (5 : 1) to give a white microcrystalline solid: yield
89 mg (94%); mp 190 ◦C (Found: C, 45.13; H, 6.97, N, 2.29.
9 D. M. Lunder, E. B. Lobkovsky, W. E. Streib and K. G. Caulton, J. Am.
Chem. Soc., 1991, 113, 1837.
10 A. Albinati, V. I. Bakhmutov, K. G. Caulton, E. Clot, J. Eckert, O.
Eisenstein, D. G. Gusev, V. V. Grushin, B. E. Hauger, W. T. Klooster,
T. F. Koetzle, R. K. McMullan, T. J. O’Loughlin, M. Pe´lissier, J. S.
Ricci, M. P. Sigalas and A. B. Vymenits, J. Am. Chem. Soc., 1993, 115,
7300.
C26H49ClIrNO2P2 requires C, 44.78; H, 7.08, N, 2.00%). IR (KBr):
−1
=
m(NH) 3410, m(IrH) 2115, m(CO) 2000, m(C O) 1615 cm . NMR
(CDCl3): dH (90 MHz) 7.77–7.47 (5 H, br m, C6H5), 4.25 (1 H,
br s, NH), 2.72 (6 H, m, PCHCH3), 1.56 [36 H each, br dvt, N =
13.6, J(H,H) = 7.0 Hz, PCHCH3], −8.78 [1 H, dt, J(P,H) = 15.4,
J(H,H) = 2.0 Hz, IrH]; dP (36.2 MHz) 18.6 (s, d in off-resonance).
11 E. J. Probitts, D. R. Saunders, M. H. Stone and R. J. Mawby, J. Chem.
Soc., Dalton Trans., 1986, 1167.
12 W. D. Jones and F. J. Feher, Inorg. Chem., 1984, 23, 2376.
13 J. S. Merola, Organometallics, 1989, 8, 2973; H. E. Selnau and J. S.
Merola, Organometallics, 1993, 12, 1583.
[IrH{j2-O,O-O2CPh}(Cl)(PiPr3)2] 29. A suspension of 1
(210 mg, 0.23 mmol) in toluene (5 cm3) was treated with PiPr3
(0.21 cm3, 1.05 mmol) and benzoic acid (56 mg, 0.46 mmol)
and stirred for 30 min at room temperature. The solvent was
evaporated in vacuo and the oily residue was dissolved in hexane
(2 cm3). After the solution was stored for 12 h at −78 ◦C, a yellow
microcrystalline solid precipitated which was separated from the
mother-liquor, washed with small amounts of hexane (−20 ◦C)
and dried: yield 273 mg (87%); mp 132 ◦C (Found: C, 44.77;
H, 7.37. C25H48ClIrO2P2 requires C, 44.80; H, 7.22%). MS (70
eV): m/z 670 (M+), 634 (M+ − HCl), 548 (M+ − PhCO2H), 510
14 R. H. Crabtree and C. P. Parnell, Organometallics, 1985, 4, 519; and
references cited therein.
15 W. Strohmeier and F. J. Mu¨ller, Z. Naturforsch., Teil B, 1969, 24, 770;
W. Strohmeier, R. Fleischmann and T. Onoda, J. Organomet. Chem.,
1971, 28, 281; W. Strohmeier and M. Lukacs, J. Organomet. Chem.,
1977, 133, C47.
16 A. J. Deeming and B. L. Shaw, J. Chem. Soc. A, 1969, 1128.
17 L. Dahlenburg and R. Nast, J. Organomet. Chem., 1976, 110, 395; U.
Behrens and L. Dahlenburg, J. Organomet. Chem., 1976, 116, 103.
18 M. L. H. Green and W. E. Lindsell, J. Chem. Soc. A, 1969, 2215.
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and references cited therein.
+
−1
=
(M − PiPr3). IR (KBr): m(IrH) 2275, m(C O) 1530 cm . NMR
(CD2Cl2): dH (90 MHz) 8.37, 7.36 (5 H, both br m, C6H5), 2.88
(6 H, m, PCHCH3), 1.63, 1.50 [18 H each, dvt, N = 13.4, J(H,H) =
6.7 Hz, PCHCH3], −34.48 [1 H, t, J(P,H) = 12.5 Hz, IrH]; dP (36.2
MHz) 20.0 (s, d in off-resonance).
Acknowledgements
21 M. Mediati, G. N. Tachibana and C. M. Jensen, Inorg. Chem., 1990,
29, 3.
We thank the Deutsche Forschungsgemeinschaft (SFB 347) and
the Fonds der Chemischen Industrie for financial support, and
BASF AG and Degussa AG for chemicals. Moreover, we are
also most grateful to Mrs R. Schedl and Mr C. P. Kneis (DTA
measurements and elemental analyses), Dr G. Lange and Mr
F. Dadrich (mass spectra), Dr W. Buchner and Mrs M.-L. Scha¨fer
(NMR spectra), and to Professor O. Eisenstein for various
stimulating discussions.
22 A. C. Albe´niz, G. Schulte and R. H. Crabtree, Organometallics, 1992,
11, 242.
23 M. Schulz, Ph.D. Thesis, Universita¨t Wu¨rzburg, 1991.
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25 M. F. McGuiggan and L. H. Pignolet, Inorg. Chem., 1982, 21, 2523.
26 K. Peters, unpublished results.
27 M. D. Fryzuk, P. H. MacNeil and S. J. Rettig, J. Am. Chem. Soc., 1985,
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28 A. L. Casalnuovo, J. C. Calabrese and D. Milstein, Inorg. Chem., 1987,
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2606 | Dalton Trans., 2006, 2597–2606
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