Synthesis and characterization of new intramolecular C-H activated rhodium(III) and iridium(III) complexes containing functionalized triphenylphosphines

Article abstract of DOI:10.1021/om980929g

The hemilabile tertiary phosphine ether and phosphine ester compounds o-Ph₂PC₆H₄CH₂-OMe (DPBE) and o-Ph₂PC₆H₄CH₂OC(O)Et (DPES) and their reactions with different Rh(I)

Full text of DOI:10.1021/om980929g

2198
Organometallics 1999, 18, 2198-2205
Syn th esis a n d Ch a r a cter iza tion of New In tr a m olecu la r
C-H Activa ted Rh od iu m (III) a n d Ir id iu m (III) Com p lexes
Con ta in in g F u n ction a lized Tr ip h en ylp h osp h in es
Sven Sjo¨vall, Maria J ohansson, and Carlaxel Andersson*
Inorganic Chemistry 1, Centre for Chemistry and Chemical Engineering, Lund University,
P.O. Box 124, S-221 00 Lund, Sweden
Received November 16, 1998
The hemilabile tertiary phosphine ether and phosphine ester compounds o-Ph2PC6H4CH2-
OMe (DPBE) and o-Ph2PC6H4CH2OC(O)Et (DPES) and their reactions with different Rh(I)
and Ir(I) precursor complexes have been investigated. It is shown that both DPBE and DPES
are capable of undergoing oxidative metal insertions at the benzylic positions with the
displaced protons appearing as apical hydride ligands in the resulting octahedral complexes.
The solution structures of all oxidative addition adducts have been unambiguously identified
by various NMR techniques. Also, single-crystal X-ray diffraction studies have been performed
for the complexes [RhCl(2,5-NBD)(DPES)] and [IrH(1,5-COD)(DPES)][BF4].
Ch a r t 1. Str u ctu r es of th e Hem ila bile Ter tia r y
P h osp h in es DP BE a n d DP ES
In tr od u ction
Cyclometalated transition-metal complexes are be-
coming increasingly important in catalysis.1 Complexes
formed by intramolecular insertion of a transition metal
into sp2 C-H bonds have for instance been used in
dehydrogenation,2 coupling,3 insertion,4 hydrogenation,5
addition,6 activation of hydrocarbons,7 and asymmetric
reactions.8 Catalytic applications could also be extended
to transition-metal complexes with intramolecular metal
insertion into sp3 C-H bonds. However, to the best of
our knowledge, there are only a few reports of this being
successful. Palladacycles, formed by benzylic C-H
activation of tri-o-tolylphosphine or 1,3-bis[(diisopropyl-
phosphino)methyl]-2,4,6-trimethylbenzene, are extremely
efficient catalysts in the Heck reaction.9 Therefore,
developing new functionalized tertiary phosphines ca-
pable of forming metallacycles by intramolecular metal
insertion into sp3 C-H bonds could be of importance in
catalysis.
In this article we report our attempts to elicit inser-
tion of transition-metal centers into tertiary phosphine
ligands containing benzylic C-H bonds adjacent to a
methoxy or an ester group. By using a functionalized
tertiary phosphine (called hemilabile when it posseses
a multidentate capacity due to hard and soft donor
groups), with an available chelating side chain, cyclo-
metalation can be obtained through chelate-assisted
intramolecular oxidative insertion by a transition-metal
center. This has been achieved with C-H, N-H, Si-
H, O-H, and C-C bonds.10 The tertiary phenylphos-
phines used in this article are o-Ph2PC6H4CH2OMe
(DPBE) and o-Ph2PC6H4CH2OC(O)Et (DPES) (Chart 1).
Both DPBE and DPES have oxygen as the heteroatom,
directing the benzylic group in the vicinity of the
transition-metal center. The donor strengths of the
heteroatoms, the steric bulk of the phosphine ligands,
the relative stability between different chelate sizes, and
the electron densities at the transition-metal centers are
expected to govern the preferred coordination modes.
(1) (a) Steenwinkel, P.; Gossage, R. A.; van Koten, G. Chem. Eur.
J . 1998, 4, 759. (b) Ryabov, A. D. Chem. Rev. 1990, 90, 403.
(2) (a) Gupta, M.; Hagen, C.; Flescher, R. J .; Kaska, W. C.; J ensen,
C. M. Chem. Commun. 1996, 2083. (b) Gupta, M.; Kaska, W. C.;
J ensen, C. M. Chem. Commun. 1997, 461. (c) Gupta, M.; Kaska, W.
C.; Cramer, R.; J ensen, C. M. J . Am. Chem. Soc. 1997, 119, 840. (d)
Xu, W.-W.; Rosini, G. P.; Gupta, M.; J ensen, C. M.; Kaska, W. C.;
Krogh-J espersen, K.; Goldman, A. S. Chem. Commun. 1997, 2273.
(3) (a) van Koten, G. Pure Appl. Chem. 1994, 66, 1455. (b) Ohff, M.;
Ohff, A.; van der Boom, M. E.; Milstein, D. J . Am. Chem. Soc. 1997,
119, 11687.
(4) (a) Canty, A. J .; van Koten, G. Acc. Chem. Res. 1995, 28, 406.
(b) Donkervoort, J . G.; Vicario, G. L.; J astrzebski, J . T. B. H.; Gossage,
R. A.; Cahiez, G.; van Koten, G. J . Organomet. Chem. 1998, 558, 61.
(5) (a) Lewis, L. N. J . Am. Chem. Soc. 1986, 108, 743. (b) Bedford,
R. B.; Castillo`n, S.; Chaloner, P. A.; Claver, C.; Fernandez, E.;
Hitchcock, P. B.; Ruiz, A. Organometallics 1996, 15, 3990. (c) Bianchini,
C.; Barbaro, P.; Scapacci, G.; Farnetti, E.; Graziani, M. Organometallics
1998, 17, 3308.
(6) (a) Knapen, J . W. J .; van der Made, A. W.; de Wilde; J . C.; van
Leeuwen, P. W. N. M.; Wijkens, P.; Grove, D. M.; van Koten, G. Nature
1994, 372, 659. (b) Grove, D. M.; van Koten, G.; van Beek, J . A. M. J .
Organomet. Chem. 1989, 372, C1.
(7) (a) Nemah, S.: J ensen, C.; Binamira-Soriaga, E.; Kaska, W. C.
Organometallics 1983, 2, 1442. (b) Rybtchinski, B.; Vigalok, A.; Ben-
David, Y.; Milstein, D. J . Am. Chem. Soc. 1996, 118, 12406.
(8) (a) Gorla, F.; Togni, A.; Venanzi, L. M.; Albinati, A.; Lianza, F.
Organometallics 1994, 13, 1607. (b) Longmire, J .; Xumu, Z. Organo-
metallics 1998, 17, 4374.
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H.; O¨ fele, K.; Beller, M. Chem. Eur. J . 1997, 3, 1357. (b) Beller, M.;
Riermeier, T. H. Eur. J . Inorg. Chem. 1998, 29. (c) Reference 3b.
(10) For examples see: (a) Crabtree, R. H. Chem. Rev. 1985, 85,
245. (b) Hedden, D.; Roundhill, D. M. Inorg. Chem. 1986, 25, 9. Hedden,
D.; Roundhill, D. M.; Fultz, W. C.; Rheingold, A. R. J . Am. Chem. Soc.
1984, 106, 5014. (c) Auburn, M. J .; Holmes-Smith, R. D.; Stobart, S.
R. J . Am. Chem. Soc. 1984, 106, 1314. (d) Landvatter, E. F.; Rauchfuss,
T. B. Organometallics 1982, 1, 506. (e) Reference 7b.
10.1021/om980929g CCC: $18.00 © 1999 American Chemical Society
Publication on Web 05/06/1999

C-H Activated Rh(III) and Ir(III) Complexes
Organometallics, Vol. 18, No. 11, 1999 2199
Ch a r t 2. Str u ctu r es of Com p lexes 1-5 w ith th e
reacted [M(diene)2][X] with 1 equiv of DPES to prepare
[Rh(2,5-NBD)(DPES)][CF3SO3] (3) and [IrH(1,5-COD)-
(DPES)[BF4] (4) from their respective reactions (Chart
2).
Liga n d DP ES
For complex 3, the IR spectrum clearly demonstrates
that the ester carbonyl oxygen is coordinated to the
rhodium center, thus forming an eight-membered P,O-
chelating ligand (Table 1). Also, the 31P{1H} NMR
spectroscopic analysis is consistent with a 4-coordinate
Rh(I) monomer (Table 1). To be able to detect all olefinic
1
resonances in the 2,5-NBD ligand, the H NMR spec-
troscopic investigation of 3 was performed at -40 °C.
The loss of information in the room-temperature spec-
trum probably results from weak coordination of the
ester group, which allows a dynamic behavior, although
an isomerization process of the square-planar complex
cannot be ruled out. It is worth noting that the 31P{1H}
NMR chemical shift for 3 shows a very small ring shift
Resu lts a n d Discu ssion
1
In general, intramolecular C-H activation is possible
by synthesizing complexes containing metal centers
which have at least two vacant coordination sites and
which readily undergo oxidative addition. Such com-
plexes are known for all platinum group transition
metals, and in the present study we have chosen to work
with Rh(I) and Ir(I) complexes.
effect due to chelation, and the J RhP value is virtually
the same as for 1. The elemental analysis is somewhat
unsatisfactory, and related complexes have been re-
ported to be thermally unstable.10b
Complex 4 is an off-white powder like many other
octahedral hydridoiridium(III) derivatives.13 It is very
stable and does not react with an additional 1 equiv of
DPES under an atmosphere of molecular hydrogen at
ambient conditions. The 1H NMR spectrum of 4 exhibits
a hydride signal as a doublet at -19.2 ppm, and the
remaining benzylic proton gives rise to a doublet at 6.87
ppm. Irradiation of the 31P signal at 33.9 ppm results
in collapse of both these signals into singlets. The
Tr a n sition -Meta l Com p lexes w ith DP ES. Treat-
ment of the olefin dimer [µ-MCl(diene)]2 with 2 equiv
of the tertiary phosphine o-(diphenylphosphino)benzoic
acid ethyl ester (DPES) results in the expected bridge
cleavage, forming the complexes [MCl(diene)(DPES)]
from their respective reactions (M ) Rh, Ir; diene ) 2,5-
NBD, 1,5-COD). Both 1 and 2 are 4-coordinate with the
monodentately coordinated P atom donor cis to the
chloride atom (Chart 2). The spectroscopic properties
of 1 and 2 are similar (Table 1). Both complexes exhibit
31P NMR signals shifted about 30-40 ppm downfield
from those of uncoordinated DPES, and the value of
1J RhP for 1 is typical for a rhodium(I)-complexed mono-
dentate phosphine ligand trans to an olefin.11 Also, the
IR spectroscopic analysis reveals the ester carbonyl
stretching frequency at 1737 cm-1 for both 1 and 2,
which exactly matches the frequency for free DPES.
Apparently, intramolecular insertion into the benzylic
C-H bond does not occur in these neutral complexes,
although analogous transition-metal complexes with
o-Ph2PC6H4CHO as the hemilabile ligand have previ-
ously been found to undergo intramolecular C-H ad-
dition.12
The reluctance of 1 and 2 to undergo C-H oxidative
addition may be due to the absence of any intramolecu-
lar interaction between the hinged functional group and
the metal center.10b By removal of the Cl atom from 1
and 2, with a halide-abstracting agent, an intramolecu-
lar chelate formed by bidentate coordination of the
hemilabile DPES ligand is expected, bringing the ben-
zylic group in the vicinity of the transition-metal center.
An alternative way to form such cationic 4-coordinate
d8 complexes is the reaction of DPES with the complex
[M(diene)2][X]. We have chosen this latter method and
2
coupling constant J PH (13 Hz) at -19.2 ppm is of
3
normal magnitude,14 but the J PH value (1.8 Hz) at 6.87
ppm is surprisingly low for a cyclometalated species.15
The methylene protons of the terminal ethyl group
resonate as a multiplet, implying the appearance of
conformers. We believe restricted rotation of the ester
group, due to coordination, is the probable cause for this.
IR spectroscopy also provides evidence for the coordina-
tion of the ester carbonyl oxygen and the presence of a
hydride ligand (Table 1). The rather high Ir-H stretch-
ing frequency (2210 cm-1) indicates that the hydride is
situated trans to a ligand low in the trans-influence
series, i.e., the ester carbonyl.16 An HMQC NMR experi-
ment gives further verification of a cyclometalated
species; the broad 13C signal at 92.3 ppm correlates with
1
the H signal at 6.87 ppm.
Since the hydride, the alkene π-bond, and the iridium
center in 4 are coplanar, the exclusive cis addition of
the metal hydride to the alkene would be expected.17
The reason for the reluctance of this migratory insertion
reaction is not obvious. Most probably, extensive polar-
ization of the electron density from the metal center
toward the diene creates a particularly strong Ir-H
bond. Also, an equilibrium between 4 and a 16-electron
Ir(III) η1:η2 adduct in solution could also be possible.
However, we rule this out, since the NMR spectroscopic
(13) Werner, H.; Schulz, M.; Windmu¨ller, B. Organometallics 1995,
14, 3659.
(14) For examples see ref 7b.
(15) Sjo¨vall, S.; Kloo, L.; Nikitidis, A.; Andersson, C. Organometallics
1998, 17, 579.
(16) J esson, J . P. Transition Metal Hydrides; Muetterties, E. L., Ed.;
Dekker: New York, 1971; Chapter 4.
(11) Pregosin, P. S.; Kunz, R. W. 31P and 13C NMR of Transition
Metal Phosphine Complexes; Springer-Verlag: New York, 1979.
(12) (a) Rauchfuss, T. B. J . Am. Chem. Soc. 1979, 101(4), 1045. (b)
Ko, J .; J oo, W. C. Bull. Korean Chem. Soc. 1987, 8, 372. (c) Gao, J .-X.;
Wang, J .-Z.; Hu, S.-Z.; Wan, H.-L. Gaodeng Xuexiao Huaxue Xuebao
1995, 16, 666.
(17) J ames, B. R. Compr. Organomet. Chem. 1982, 8, 306.

2200 Organometallics, Vol. 18, No. 11, 1999
Ta ble 1. 31P {1H} NMR Da ta (p p m ) a n d IR Sp ectr a l Da ta (cm -1
Sjo¨vall et al.
)
31P NMRa
IR
31P NMRa
IRh
complex
δ
1J RhP
2J PP
ν(CdO)
ν(M-H)
complex
δ
1J RhP
2J PP
ν(O-Me)
ν(M-H)
DPESb,f
1b,f
-15.8 s
24.3 d
17.4 s
21.6 d
33.9 s
54.5 ddd
40.2 ddd
25.3 dt
1737 s
1737 s
1737 s
1711 m
1593 m
DPBEb,f
6b,f
-14.8 s
23.2 d
11.0 s
49.7 d
25.8 d
6.0 d
1065 s
1030 m
1031 s
1038 s
1047 s
1069 m
1047 s
1069 m
166
165
169
204
2b,f
7c,f
3e,f
8b,f
4b,g
2210 w
2127 w
9a d,g
390
390
2210 w
2210 w
5c,g
113
110
85.6
368, 22.4
368, 24.1
22.1
1617 m
9bd,g
16.2 bs
5.3 bs
a
d
All J values in Hz. b 31P{1H} NMR in CDCl3. c 31P{1H} NMR in CD2Cl2. 31P{1H} NMR in C6D6. e 31P{1H} NMR in CD2Cl2 at -40 °C.
f IR spectra obtained in CH2Cl2. g KBr disk. The assignments of the ν(O-Me) bands are tentative because of the possibilities of overlapping
stretching frequencies.
h
analyses did not reveal any isomerization of the coor-
dinated diene.
Ch a r t 3. Str u ctu r es of Com p lexes 6-9 w ith th e
Liga n d DP BE
So far we have not effected intramolecular insertion
of a rhodium center into the benzylic C-H bond of the
DPES ligand. Apparently, as seen for complex 3, biden-
tate coordination of the hemilabile DPES ligand alone
is insufficient to elicit the oxidative-addition reaction.
It could well be that the π-accepting diene ligand
decreases the electron density at the rhodium center to
such an extent that C-H activation is rendered
impossible.10b,15 If the diene ligand in 3 were replaced
with σ-donating phosphine ligands, a significantly larger
electron density would be imparted on the transition-
metal center, and this could be a fruitful way to achieve
the desired oxidative-addition reaction. We have there-
fore replaced the 2,5-NBD ligand with such stronger
electron donors.
2
-17.4 ppm and J RhH ) 20 Hz at 6.09 ppm. The
magnitudes of the 2J PH coupling constants are consistent
with all phosphorus atoms being cis to the hydride.
Final confirmation of metallacyclic formation in 5 is
given by its 13C{1H} and HMQC NMR spectroscopic
data; the benzylic 13C resonance appears at 103.8 ppm
Complex 5 was synthesized by treating the precursor
[Rh(PPh3)2(2,5-NBD)][PF6] with 1 equiv of DPES under
an atmosphere of molecular hydrogen. The IR spectrum
suggests that the carbonyl oxygen of the DPES ligand
is coordinated to the rhodium center and also reveals a
Rh-H band at 2127 cm-1 (Table 1), which is charac-
teristic of a hydride ligand on Rh(III) trans to a ligand
low in the trans-influence series.16 Analysis of the 31P-
{1H} NMR spectrum, performed at -40 °C to decrease
line width, exhibits three different signals; ABCX pat-
terns occur at 54.5 and 40.2 ppm, and an A2BX pattern
appears at 25.3 ppm (Table 1). The two downfield
(1J RhC ) 87 Hz, J PC ) 23, 10, 3 Hz), and it correlates
2
1
with the benzylic H resonance at 6.09 ppm.
Tr a n sit ion -Met a l Com p lexes w it h DP BE . As
shown, oxidative insertion of a rhodium or iridium
center into the benzylic C-H bond of DPES is facile,
given the correct conditions. Use of these same strate-
gies with o-(diphenylphosphino)benzoic acid methyl
ether (DPBE) as the ligand have also been investigated.
2
signals indicate two J PP couplings each, both normal
for phosphorus atoms situated trans or cis to each other,
respectively. The low-field resonance at 54.5 ppm is
assigned to the cyclometalated DPES ligand.15 The
upfield resonance at 25.3 ppm displays a somewhat
The complexes [Rh(2,5-NBD)(DPBE)][CF3SO3] (6) and
[Ir(1,5-COD)(DPBE)][BF4] (7) were synthesized by meth-
ods analogous to that of 3 (Chart 3). The IR spectro-
scopic measurements reveal the stretching frequencies
for the OMe bands at 1030 (6) and 1031 cm-1 (7),
respectively (Table 1). These shifts of the ether vibra-
tions to lower wavenumbers, compared to that of free
DPBE (1065 cm-1), are explicable in terms of ring
closure of the DPBE ligand.18 The existence of six-
membered P,O-chelates is further substantiated by the
NMR spectroscopic investigations. In the 1H NMR
spectra of 6 and 7, the methyl resonances are shifted
0.3-0.5 ppm downfield of that observed for free DPBE
due to coordination of the ether oxygen, which results
in deshielding of the adjacent hydrogens.19 The 31P{1H}
NMR spectrum of 6 resembles the 31P{1H} NMR spectra
of 1 and 3 (Table 1).
2
broad doublet of triplets resulting from two cis J PP
coupling constants of virtually the same magnitude.
1
Finally, the small J RhP coupling constant (85.6 Hz)
apparent from the signal at 25.3 ppm implies that this
PPh3 ligand is coordinated trans to a highly trans-
influencing atom, i.e., the metallacyclic benzylic carbon.
These data are only compatible with the chemical
composition [RhH(PPh3)2(DPES)][PF6], and the only
possible coordination geometry for complex 5 is depicted
in Chart 2.
Further verification of the proposed structure of 5 is
1
provided by its H NMR spectrum, which exhibits two
characteristic signals with an intensity equal to one
hydrogen each: a doublet of doublet of triplets at -17.3
ppm and a broad doublet at 6.09 ppm. By performing
1H{31P} NMR spectroscopy, we can determine the
(18) Bader, A.; Lindner, E. Coord. Chem. Rev. 1991, 108, 27.
(19) Rauchfuss, T. B.; Patino, F. T.; Roundhill, D. M. Inorg. Chem.
1975, 14, 652.
1
coupling constants: J RhH ) 20 Hz, 2J PH ) 16, 10 Hz at

C-H Activated Rh(III) and Ir(III) Complexes
Organometallics, Vol. 18, No. 11, 1999 2201
To impart a greater electron density on the rhodium
center, we first carried out a procedure analogous to that
employed in the synthesis of 5, but with DPBE as the
hemilabile phosphine ligand. However, there was a
tendency for the reaction to lead to a mixture of
products. Therefore, the precursor [Rh(2,5-NBD)2][CF3-
SO3] was used instead and treated with 2 equiv of DPBE
in the synthesis of the complex [Rh(DPBE)2][CF3SO3]
(8) (Chart 3). To enable replacement of both dienes in
the precursor, the synthesis of 8 has to be carried out
under an atmosphere of molecular hydrogen, which is
not the case with tertiary hemilabile alkylphosphines.19
Oxidative addition of the rhodium center into the
benzylic C-H bond does not occur in this complex,
although the analogous complex with o-Ph2PC6H4CH2N-
(CH3)C(O)Et as the hemilabile ligand has previously
been found to undergo intramolecular benzylic C-H
activation.15
The NMR spectroscopic analysis of 8 is consistent
with a square-planar Rh(I) complex of cis configuration
(Table 1). The 31P{1H} NMR spectrum exhibits an A2X
system, with a doublet at 49.7 ppm, caused by two
chemically equivalent P atoms. The relatively large
1J RhP value is in accordance with the lower trans-
influencing ether oxygen atoms being trans to the
F igu r e 1. DIAMOND drawing of complex 1.22
diastereotopic. This phenomenon, which lowers the
symmetry of the complex, has been detected before in
cyclometalated adducts.15 In the 31P{1H} NMR spec-
1
phosphines.20 The H NMR spectrum of 8 is not signifi-
2
cantly different from those of the aforementioned com-
plexes 6 and 7; i.e., the chemical shift for the ether
functional groups is consistent with two complexed
oxygens. In addition, the IR spectrum also supports the
NMR spectra with the stretching frequency for the OMe
band at 1038 cm-1 (Table 1). However, the elemental
analysis deviated from that calculated with respect to
the carbon content, most likely because of a great
propensity for the complexes [Rh(P,O)2]+ to decompose.21
Clearly, oxidative metal insertion into the DPBE
ligand is not as facile as for the DPES ligand. Also, on
the basis of the synthesis of complexes 2, 4, and 5, a
transition-metal center (i) being from the third transi-
tion series, (ii) bearing a higher electron density, and
(iii) coordinating the ligand’s heteroatom is the most
plausible candidate to oxidatively insert into a C-H
bond. To fulfill all three criteria and circumvent the
need of an atmosphere of hydrogen during the synthesis
(cf. complex 8), we treated the cyclooctene complex
[µ-IrCl(C8H14)2]2 with 4 equiv of DPBE to form complex
9.
From repetition of the synthesis of 9 several times, it
is clear that the complex exists as two geometrical
isomers in an approximately 1:1 ratio, which we have
been unable to separate. However, since the relative
isomer yield varies slightly between preparations, we
are able to assign those NMR resonances due to 9a
separately from those due to 9b. The 1H NMR spectrum
exhibits two hydride signals; a doublet of doublets at
-19.8 ppm (2J PH ) 21, 11 Hz) for 9a and a triplet at
-20.0 ppm (2J PH ) 16 Hz) for 9b. The magnitudes of
the coupling constants for both isomers are in ac-
cordance with the phosphorus atoms being cis to the
hydride. Also, the benzylic protons in the P,O-chelating
DPBE ligand appear as coupled doublets and hence are
trum, 9a exhibits an ABX pattern with J PP ) 390 Hz,
implying a trans disposition of the P atoms (Table 1).
However, we could not detect any coupling for 9b, since
its 31P signals appeared just as broad singlets. Most
2
likely this is because we have a very small cis J PP
coupling; i.e., the P atoms are trans to highly trans-
influencing atoms. For both isomers, the low-field 31P
signal is assigned to the metalated DPBE ligand.15 The
IR spectrum of 9 shows the presence of a hydride and
both coordinated and uncoordinated ether groups (Table
1). The broad band at 2210 cm-1 can be taken as
indicative of a hydride ligand on Ir(III) trans to a ligand
low in the trans-influence series.16 Also, the coordinated
OMe group, which gives rise to an absorption at 1047
cm-1, shows only a weak ring shift. These IR properties
are only explicable if the hydride ligand and the
coordinated ether group are situated trans to each other.
Hence, the spectroscopic data are only compatible with
the chemical composition [IrHCl(DPBE)2], and the
geometric isomers are depicted in Chart 3.
Since we could not detect the remaining benzylic
protons on the metallacyclic carbons of 9, it was vital
to perform further NMR investigations. In the 13C{1H}
NMR spectrum two characteristic signals appeared, a
doublet at 91.4 ppm (2J PC ) 98 Hz) and a broad singlet
at 58.6 ppm. An HMQC NMR experiment verified that
these 13C signals correlate with one doublet each in the
1H NMR spectrum, coincidentally lying in the aromatic
region.
In summary, from this study it is clear that the
hemilabile phosphines DPES and DPBE are capable of
oxidatively adding a benzylic C-H bond to a platinum-
group metal, given the correct conditions.
Cr ysta l Str u ctu r es. Single crystals of 1 were well-
formed yellow plates belonging to the space group P1h.
A view of the molecular structure is shown in Figure 1,
and selected bond distances and angles are listed in
Table 2.
(20) Lindner, E.; Wang, Q.; Hermann, A. M.; Fawzi, R.; Steimann,
M. Organometallics 1993, 12, 1865.
(21) Lindner, E.; Andres, B. Chem. Ber. 1987, 120, 761.

2202 Organometallics, Vol. 18, No. 11, 1999
Sjo¨vall et al.
Ta ble 2. Selected Bon d An gles a n d Dista n ces w ith
Esd ’s for Com p lex 1
Bond Distances (Å)
Rh-P
2.3016(8)
2.354(1)
2.102(3)
2.106(3)
2.209(3)
2.192(3)
C3-O1
1.342(4)
1.177(5)
1.432(3)
1.392(4)
1.369(4)
Rh-Cl
C3-O2
Rh-C23
Rh-C24
Rh-C26
Rh-C27
C4-O1
C23-C24
C26-C27
Bond Angles (deg)
P-Rh-Cl
91.15(4)
98.68(8)
103.57(8)
166.23(9)
154.05(9)
157.18(8)
Cl-Rh-C24
Cl-Rh-C26
Cl-Rh-C27
Rh-P-C10
Rh-P-C11
Rh-P-C17
156.52(9)
96.36(10)
96.32(9)
112.1(1)
114.6(1)
116.9(1)
P-Rh-C23
P-Rh-C24
P-Rh-C26
P-Rh-C27
Cl-Rh-C23
The coordination geometry around the rhodium center
is pseudo square planar, illustrated for instance by the
bond angle for P-Rh-Cl (91.15(4)°). The greatest
deviation from the least-squares plane through the Rh,
Cl, and P atoms and the midpoints of the two coordi-
nated carbon double bonds is 0.075 Å for the center
between C26 and C27. Due to ring strain in the η2:η2-
coordinating 2,5-NBD ligand, the angle between the
central atom and the midpoints of the C23-C24 and
C26-C27 double bonds is decreased to 71.8°. The Rh-P
(2.3016(8) Å) and Rh-Cl (2.354(1) Å) bond lengths are
in good agreement with those reported for the related
complex [RhCl(1,5-COD){Ph2PNHP(O)Ph2-P}].23 The
greater trans influence exerted by the P atom than the
Cl atom results in a significant difference in the
rhodium to carbon distances of the coordinated diene.
Whereas the C23 and C24 atoms (trans to Cl) are
located at a distance of 2.102(3) and 2.106(3) Å from
the metal center, the Rh-C bond lengths for C26 and
C27 (trans to P) are longer by ca. 0.1 Å. In accordance
with this, the double-bond length for C26-C27 (1.369-
(4) Å) is shorter than for C23-C24 (1.392(4) Å). All other
bond distances and angles lie in the expected range.
The strong spectroscopic evidence suggesting 4 to be
the result of an oxidative addition of a C-H bond to
the iridium center has been confirmed by a single-
crystal X-ray diffraction investigation. Slow diffusion of
diethyl ether into an acetone solution led to the deposi-
tion of 4 as colorless plates. Selected bond distances and
angles are listed in Table 3.
As seen in Figure 2, the octahedral geometry around
the iridium atom is considerably distorted, as illustrated
by the bond angles O2-Ir-H1 (171.0(16)°) and C4-Ir-
H1 (92.2(16)°). The bond angles P-Ir-C4 and C4-Ir-
O2 are decreased to 80.99(14) and 79.4(2) Å, respec-
tively, due to ring strain in the two five-membered
chelates. The observed bond distance between the
iridium and the hydride atom (1.516(45) Å) is similar
to those established for other hydridoiridium(III) com-
plexes.24 Also, the Ir-C4 bond length of 2.070(5) Å is
in the region of other reported cyclometalated transi-
tion-metal complexes.25 The bond distance for Ir-O2
F igu r e 2. DIAMOND drawing of complex 4.22
Ta ble 3. Selected Bon d An gles a n d Dista n ces w ith
Esd ’s for Com p lex 4
Bond Distances (Å)
Ir-P
2.290(1)
2.070(5)
2.163(4)
2.286(5)
2.298(5)
2.267(6)
Ir-C28
2.283(5)
1.516(45)
1.262(6)
1.277(7)
1.372(8)
1.374(8)
Ir-C4
Ir-O2
Ir-C23
Ir-C24
Ir-C27
Ir-H1
C3-O2
C3-O1
C23-C24
C27-C28
Bond Angles (deg)
P-Ir-C4
80.99(14)
C4-Ir-C24
C4-Ir-C27
C4-Ir-C28
O2-Ir-H1
O2-Ir-C23
O2-Ir-C24
O2-Ir-C27
O2-Ir-C28
Ir-C4-O1
161.1(2)
91.5(2)
95.1(2)
171.0(16)
117.1(2)
83.0(2)
78.5(2)
113.6(2)
107.5(3)
P-Ir-O2
90.24(10)
91.8(15)
97.74(14)
106.2(2)
167.53(15)
154.9(2)
79.4(2)
P-Ir-H1
P-Ir-C23
P-Ir-C24
P-Ir-C27
P-Ir-C28
C4-Ir-O2
C4-Ir-H1
C4-Ir-C23
92.2(16)
163.5(2)
(2.163(4) Å) is significantly shorter than for [IrHCl-
{κ2(C,P)-CH2OCH2CH2P-i-Pr2}{κ2(P,O)-i-Pr2PCH2CH2-
OMe}] (2.339(4) Å) and [IrCl2{κ2(C,P)-CH2N(Me)2CH2-
CH2P-i-Pr2}{κ2(P,N)-i-Pr2PCH2CH2N(Me)2}][Cl] (2.264(6)
Å), which probably reflects a higher donor strength of
the ester group compared to an ether or amine group.13
The following properties reveal a very small difference
in trans influence between the P and C4 donor: (i) the
Ir-C(olefin) distances for Ir-C23 and Ir-C24 are 2.286-
(5) and 2.298(5) Å, respectively, compared to the values
for Ir-C27 (2.267(6) Å) and Ir-C28 (2.283(5) Å); (ii) the
respective distances between the sp2-carbon atoms in
the diene ligand are 1.372(8) Å for C23-C24 and 1.374-
(8) Å for C27-C28. All other bond distances and angles
lie in the expected range.
(22) Brandenburg, K. DIAMOND: Crystal Structure Information
System, Version 1.2; 1997.
(23) Slawin, A. M. Z.; Smith, M. B.; Woollins, J . D. J . Chem. Soc.,
Dalton Trans. 1996, 1283.
(24) Stoutland, P. O.; Bergman, R. G. J . Am. Chem. Soc. 1988, 110,
5732. Werner, H.; Ho¨hn, A.; Dziallas, M. Angew. Chem., Int. Ed. Engl.
1986, 12, 1090.
(25) Clark, G. R.; Greene, T. R.; Roper, W. R. J . Organomet. Chem.
1985, C25, 293.
A comparison of selected structural data of 1 with
those of 4 is given in Table 4. From these data it is seen
that the side chain in the DPES ligand undergoes few
significant structural changes upon cyclometalation; the
bond angles for the atoms involved in the metallacycle
in 4 are all more acute than in 1, and the differences in

C-H Activated Rh(III) and Ir(III) Complexes
Organometallics, Vol. 18, No. 11, 1999 2203
-CH2-), 0.96 (t) and 0.95 (t) (3J HH ) 6.6 Hz, 3H, -CH3). Anal.
Calcd for C22H21O2P: C, 75.8; H, 6.1; P, 8.9. Found: C, 75.5;
H, 6.3; P, 8.9.
Ta ble 4. Com p a r ison of Str u ctu r a l Da ta (Bon d
Len gth s in Å, An gles in d eg) for Com p lexes 1 a n d 4
complex 1
complex 4
Rea ction of [µ-Rh Cl(2,5-NBD)]2 w ith DP ES. F or m a tion
of [Rh Cl(2,5-NBD)(DP ES)] (1). A dichloromethane solution
(10 mL) of [µ-RhCl(2,5-NBD)]2 (50.2 mg, 0.109 mmol) and
DPES (76.6 mg, 0.220 mmol) was stirred for 1 h at room
temperature. The solution was reduced to ca. 2 mL, and diethyl
ether (35 mL) was added, forming a bright yellow air-stable
precipitate. The powder was collected by filtration, washed
with diethyl ether (2 × 10 mL), and dried under vacuum.
Yield: 130 mg (73%). Yellow crystals were obtained by slow
diffusion of diethyl ether into a dichloromethane solution of
Ma-P
2.3016(8)
1.845(3)
1.402(4)
1.501(4)
1.432(3)
1.342(4)
1.177(5)
1.518(5)
1.476(6)
2.290(1)
1.821(5)
1.394(6)
1.502(7)
1.524(5)
1.277(7)
1.262(6)
1.480(7)
1.473(15)
P-C10
C10-C5
C5-C4
C4-O1
O1-C3
C3-O2
C3-C2
C2-C1
Ma-P-C10
P-C10-C5
C10-C5-C4
C5-C4-O1
C4-O1-C3
O1-C3-O2
O1-C3-C2
C3-C2-C1
112.79(9)
121.1(2)
121.5(2)
109.1(2)
117.0(3)
122.8(3)
109.7(3)
113.3(4)
101.7(2)
112.7(3)
118.5(4)
105.9(4)
117.7(4)
123.8(5)
116.5(7)
116.3(7)
1
3
1. H NMR: δ 7.66-7.19 (m, 13H, Ar), 6.85 (dd, J HH ) 10.5,
7.8 Hz, 1H, Ar), 6.12 (s, 2H, Ar-CH2-), 5.25 (bs, 2H, NBD),
3
3.83 (bs, 2H, NBD), 3.15 (bs, 2H, NBD), 2.32 (q, J HH ) 7.5
3
Hz, 2H, -CH2-), 1.42 (bs, 2H, NBD), 1.16 (t, J HH ) 7.5 Hz,
3H, -CH3). Anal. Calcd for C29H29ClO2PRh: C, 60.2; H, 5.1;
P, 5.4. Found: C, 60.3; H, 5.2; P, 5.4.
Rea ction of [µ-Ir Cl(1,5-COD)]2 w ith DP ES. F or m a tion
of [Ir Cl(1,5-COD)(DP ES)] (2). Using a procedure similar to
that for 1 with [µ-IrCl(1,5-COD)]2 (30.2 mg, 44.9 µmol) and
DPES (31.6 mg, 90.8 µmol) gave complex 2 as an air-stable
bright yellow powder. Yield: 50.3 mg (81%). 1H NMR: δ 7.71-
7.08 (m, 14H, Ar), 5.78 (s, 2H, Ar-CH2-), 5.16 (bs, 2H, COD),
3.00 (bs, 2H, COD), 2.34 (q, 3J HH ) 7.5 Hz, 2H, -CH2-), 2.26-
a
M ) Rh (1), Ir (4).
bond distances are all due to coordination of the carbo-
nyl functionality in 4.
Exp er im en ta l Section
3
1.28 (m, 8H, COD), 1.16 (t, J HH ) 7.5 Hz, 3H, -CH3). Anal.
Calcd for C30H33ClO2PIr: C, 53.0; H, 4.8, P, 4.3. Found: C,
53.2; H, 5.2; P, 4.3.
The apparatuses, general procedures, and purification of
solvents have been previously described.15 Pyridine was dried
with powdered potassium hydroxide, followed by distillation
over calcium dihydride, and used immediately. Propionyl
chloride was distilled and used immediately. Commercially
available reagents were purchased and used without further
purification. The compound DPBE19 and the complexes [µ-RhCl-
(2,5-NBD)]2,26 [µ-IrCl(1,5-COD)]2,27 [Ir(1,5-COD)2][BF4],28 [Rh-
(2,5-NBD)2][CF3SO3],28 [µ-IrCl(C8H14)2]2,29 and [Rh(2,5-NBD)-
(PPh3)2][PF6]30 were prepared according to literature procedures.
The tertiary phosphines are hygroscopic, but once isolated as
pure solids they are relatively stable toward oxygen.
Rea ction of [Rh (2,5-NBD)2][CF 3SO3] w ith DP ES. F or -
m a tion of [Rh (2,5-NBD)(DP ES)][CF 3SO3] (3). [Rh(2,5-
NBD)2][CF3SO3] (53.2 mg, 0.122 mmol) and DPES (42.7 mg,
0.123 mmol) were dissolved in dichloromethane (10 mL). After
the bright yellow solution was stirred for 30 min, the solvent
was concentrated under vacuum to ca. 2 mL. Dropwise addi-
tion of n-hexane (20 mL) gave a yellow precipitate. Removal
of the solvent and drying under vacuum gave the air-sensitive
complex 3. Yield: 43.1 mg (51%). 1H NMR (-40 °C in CD2-
Cl2): δ 7.75-6.89 (m, 14H, Ar), 6.27 (bs, 2H, Ar-CH2-), 5.41
(bs, 2H, NBD), 3.92 (bs, 2H, NBD), 3.46 (bs, 2H, NBD), 2.14
1H and 31P NMR spectra were recorded at 300 and 121 MHz,
3
(q, J HH ) 7.7 Hz, 2H, -CH2-) 1.43 (bs, 2H, NBD), 0.91 (t,
respectively, using a Varian Unity 300 MHz spectrometer. 13
C
3J HH ) 7.7 Hz, 3H, -CH3). Anal. Calcd for C30H29F3O5PSRh:
C, 52.1; H, 4.2; P, 4.5. Found: C, 52.9; H, 5.0; P, 4.3.
and HMQC (2D inverse H,C correlation) NMR spectra were
recorded at 125 and 500 MHz, respectively, using a Bruker
ARX 500 MHz spectrometer. Unless otherwise stated, the
NMR measurements were performed in CDCl3.
Rea ction of [Ir (1,5-COD)2][BF 4] w ith DP ES. F or m a tion
of [Ir H(1,5-COD)(DP ES)][BF 4] (4). When [Ir(1,5-COD)2]-
[BF4] (91.3 mg, 0.184 mmol) and DPES (64.3 mg, 0.184 mmol)
were mixed in dichloromethane (10 mL), the solution gradually
changed color from dark red to light yellow within minutes.
After 45 min an off-white powder was isolated by evaporation
of the solvent and washed with diethyl ether (3 × 10 mL) and
n-hexane (3 × 10 mL). Yield: 115 mg (83%). This air-stable
product can be recrystallized by slow diffusion of diethyl ether
into a solution of acetone. 1H NMR: δ 7.79-7.03 (m, 14H, Ar),
6.87 (d, 3J PH ) 1.8 Hz, 1H, Ar-C(R)H-Ir), 5.86 (m, 1H, COD),
5.25 (m, 1H, COD), 4.68 (m, 2H, COD), 2.76-2.34 (m, 8H,
COD), 2.24-1.86 (m, 2H, -CH2-), 0.68 (t, 3J HH ) 7.8 Hz, 3H,
Syn th esis of o-(Dip h en ylp h osp h in o)ben zoic Acid Eth -
yl Ester , (o-P h 2P C6H4CH2OC(O)Et) (DP ES). A solution of
o-(diphenylphosphino)benzyl alcohol10d (2.74 g, 9.39 mmol) and
pyridine (2.25 g, 28.4 mmol) in THF (10 mL) was vigorously
stirred. Propionyl chloride (0.902 g, 9.75 mmol) was added
through a septum with a syringe, and the suspension was
stirred for 1.5 h. The precipitate was removed by Schlenk
filtration and washed with THF (3 × 20 mL). Evaporation of
the combined filtrates yielded a yellow, viscous oil. The oil was
dissolved in diethyl ether (40 mL), the solution was washed
with water (5 × 30 mL), and the organic phase was dried with
magnesium sulfate. The solution was filtered and reduced to
ca. 2 mL, and n-pentane (100 mL) was added to the remaining
oil. The cloudy solution was stored overnight at -18 °C, and
the resulting white needles were isolated by filtration and
dried under vacuum. Yield: 2.0 g (61%). 1H NMR: δ 7.48-
2
-CH3), -19.2 (d, J PH ) 13 Hz, 1H, Ir-H). 13C{1H} NMR: δ
2
187.8 (s, -C(O)-), 154-126 (m, Ar), 99.9 (d, J PC ) 10 Hz,
2
COD), 98.8 (d, J PC ) 14 Hz, COD), 95.1 (s, COD), 93.0 (s,
COD), 92.3 (bs, Ar-C(R)H-Ir), 33.2 (bs, COD), 33.1 (bs, COD),
3
3
29.7 (d, J PC ) 3 Hz, COD), 28.5 (d, J PC ) 2 Hz, COD), 26.0
(s, -CH3), 8.83 (s, -CH2-) (assignment of 1H and 13C{1H}
NMR signals were confirmed by 1H{31P} and HMQC NMR
experiments). Anal. Calcd for C30H33BF4O2PIr: C, 49.0; H, 4.5;
P, 4.2. Found: C, 49.0; H, 4.7; P, 4.3.
3
7.20 (m, 13H, Ar), 6.95 (dd, J HH ) 7.5, 4.5 Hz, 1H, Ar), 5.35
(bs, 2H, Ar-CH2-), 1.95 (q) and 1.94 (q) (3J HH ) 6.6 Hz, 2H,
(26) Giordano, G.; Crabtree, R. H. Inorg. Synth. 1990, 28, 88.
(27) Herde, J . L.; Lambert, J . C.; Senoff, C. V. Inorg. Synth. 1974,
15, 19.
(28) Schenck, T. G.; Downes, J . M.; Milne, C. R. C.; Mackenzie, P.
B.; Boucher, H.; Whelan, J .; Bosnich, B. Inorg. Chem. 1985, 24, 2334.
(29) van der Ent, A.; Onderdelinden, A. L. Inorg. Synth. 1973, 14,
92.
Rea ction of [Rh (2,5-NBD)(P P h 3)2][P F 6] w ith DP ES.
F or m a tion of [Rh H(P P h 3)2(DP ES)][P F 6] (5). A cooled (-60
°C) dihydrogen saturated solution of dichloromethane (10 mL)
was transferred by stainless steel cannula to a Schlenk tube
containing [Rh(2,5-NBD)(PPh3)2][PF6] (107 mg, 0.124 mmol)
and DPES (43.1 mg, 0.124 mmol). The solution was allowed
(30) Schrock, R. R.; Osborn, J . A. J . Am. Chem. Soc. 1976, 98, 2143.

2204 Organometallics, Vol. 18, No. 11, 1999
Sjo¨vall et al.
Ta ble 5. Cr ysta llogr a p h ic Da ta for Com p lexes 1
a n d 4
to reach room temperature, and the light brown solution was
stirred for 30 min. An argon atmosphere was introduced, and
after a further 30 min the solution had become dark brown.
The solvent was removed under vacuum, resulting in a brown,
air-stable powder, which was washed with diethyl ether (3 ×
formula
fw
C29H29ClO2PRh (1) C30H33BF4O2PIr (4)
578.85
735.54
cryst size, mm3
cryst syst
space group
a, Å
0.25 × 0.17 × 0.07
0.24 × 0.23 × 0.06
1
10 mL) and n-hexane (2 × 10 mL). Yield: 112 mg (81%). H
triclinic
orthorhombic
P1h (No. 2)
9.415(2)
Pna21 (No. 33)
19.433(4)
NMR (CD2Cl2): δ 7.62-6.92 (m, 13H, Ar), 6.17 (m, 1H, Ar),
2
6.09 (bd, J RhH ) 20 Hz, 1H, Ar-CH(R)-Rh), 1.27 (m, 2H,
b, Å
9.886(2)
14.654(3)
3
1
-CH2-), 0.56 (t, J HH ) 7.2 Hz, 3H, -CH3), -17.3 (ddt, J RhH
c, Å
16.318(3)
93.90(3)
100.95(3)
117.50(3)
1301.3(5)
2
9.944(2)
90
90
90
2831.7(10)
4
1.725
) 20 Hz, J PH ) 16, 10 Hz, 1H, Rh-H). 13C{1H} NMR (CD2-
2
R, deg
â, deg
γ, deg
V, Å3
Cl2): δ 184.5 (s, -C(O)-), 151-126 (md, Ar), 103.8 (dddd, 1J RhC
) 87 Hz, 2J PC ) 23, 10, 3 Hz, Ar-CH(R)-Rh), 26.1 (s, -CH3),
8.29 (s, -CH2-) (assignment of 1H and 13C{1H} NMR signals
were confirmed by 1H{31P} and HMQC NMR experiments).
Anal. Calcd for C58H51F6O2P4Rh: C, 62.1; H, 4.6; P, 11.0.
Found: C, 61.8; H, 4.8; P, 11.0.
Z
d
calcd, g cm-3
1.477
diffractometer
smart CCD system
smart CCD system
radiation (graphite Mo KR (0.710 73 Å) Mo KR (0.710 73 Å)
monochr)
Rea ction of [Rh (2,5-NBD)2][CF 3SO3] w ith DP BE. F or -
m a tion of [Rh (2,5-NBD)(DP BE)][CF 3SO3] (6). Using a pro-
cedure similar to that for 3 with [Rh(2,5-NBD)2][CF3SO3] (49.7
mg, 0.114 mmol) and DPBE (34.9 mg, 0.114 mmol) gave com-
plex 6 as an air-sensitive yellow powder. Yield: 56 mg (75%).
1H NMR: δ 7.51-7.02 (m, 14H, Ar), 4.72 (s, 2H, -CH2-), 4.43
(bs, 2H, NBD), 3.96 (bs, 2H, NBD), 3.54 (s, 3H, -CH3), 1.43
(bs, 2H, NBD). Anal. Calcd for C28H27F3O4PSRh: C, 51.9; H,
4.4; P, 4.7. Found: C, 52.2; H, 4.6; P, 4.6.
temp, K
293(2)
0.845
ω
60
ω-scan/multiscan
0.729
293(2)
4.824
ω
60
ω-scan/multiscan
0.621
µ, mm-1
scan method
2θ(max), deg
abs cor
Tmin
Tmax
1.000
1.000
Rint
0.0249
-13 to +12
-11 to +14
-20 to +23
11 064
7691
0.0430
-24 to +28
-16 to +20
-11 to +13
23 072
8125
h
k
l
Rea ction of [Ir (1,5-COD)2][BF 4] w ith DP BE. F or m a -
tion of [Ir (1,5-COD)(DP BE)][BF 4] (7). Using a procedure
similar to that for 3 with [Ir(1,5-COD)2][BF4] (95.2 mg, 0.192
mmol) and DPBE (59.2 mg, 0.193 mmol) gave complex 7 as a
light orange powder. The complex was too unstable for
total no. of rflns
no. of unique rflns
no. of obsd rflns
(2σ(I))
no. of params
refined
6090
6129
microanalysis. Yield: 107 mg (81%). 1H NMR (CD2Cl2):
δ
308
357
7.87-7.35 (m, 14H, Ar), 5.24 (bs, 2H, COD), 5.09 (s, 2H,
-CH2-), 3.77 (s, 3H, -CH3), 3.18 (bs, 2H, COD), 2.57-1.63
(m, 8H, COD).
R
Rw
0.0370
0.0543
24.97
0.0287
0.0583
22.76
Rea ction of [Rh (2,5-NBD)2][CF 3SO3] w ith DP BE. F or -
m a tion of [Rh (DP BE)2][CF 3SO3] (8). A solution of [Rh(2,5-
NBD)2][CF3SO3] (65.7 mg, 0.151 mmol) and DPBE (93.4 mg,
0.305 mmol) in dichloromethane (10 mL) was stirred for 10
min. A freeze-pump-thaw cycle replaced the argon atmo-
sphere by molecular hydrogen. When it was stirred for 15 min,
the solution gradually changed color from red to yellow. The
atmosphere of molecular hydrogen was replaced by argon, and
after 45 min the solution was once again red. Reduction of the
solvent volume to ca. 1 mL followed by addition of diethyl ether
(20 mL) resulted in a bright orange air-sensitive precipitate.
The powder was washed with diethyl ether (3 × 5 mL) and
dried under vacuum. Yield: 103 mg (85%). 1H NMR: δ 7.63-
6.78 (m, 28H, Ar), 4.58 (s, 4H, -CH2-), 3.78 (s, 6H, -CH3).
Anal. Calcd for C41H38F3O5P2SRh: C, 56.9; H, 4.4; P, 7.2.
Found: C, 55.2; H, 4.8; P, 7.1.
rfln:param ratio
resid electron
density, e Å-3
0.504
0.725
3
3J PC ) 9 Hz, -CH2-), 79.2 (d, J PC ) 11 Hz, -CH2-), 63.6 (s,
-CH3), 61.2 (s, -CH3), 58.6 (bs, Ar-CH(R)-Ir), 54.6 (s,
1
-CH3), 52.5 (s, -CH3) (assignments of H and 13C{1H} NMR
signals were confirmed by 1H{31P} and HMQC NMR experi-
ments). Anal. Calcd for C40H38ClO2P2Ir: C, 57.1; H, 4.6; P, 7.3.
Found: C, 56.8; H, 4.7; P, 6.9.
X-r a y Str u ctu r a l An a lyses of Com p lexes 1 a n d 4. Single
crystals were grown from dichloromethane/diethyl ether (1)
and acetone/diethyl ether (4) solutions at 25 °C under an
atmosphere of argon. The crystal data and data collection and
refinement details are provided in Table 5. Intensity data were
collected at 293 K with a Smart CCD system using ω scans
and a rotating anode with Mo KR radiation (λ ) 0.710 69 Å).
All reflections were corrected for Lorentz and polarization
effects as well as absorption.31 No significant changes in
intensities were noticed throughout the data collections.
The structures were solved by Patterson methods using
SHELXS-86,32 while the structure refinements were performed
on F2 using SHELXL-93.33 All non-H atoms were refined with
anisotropic displacement parameters, while the hydrogen
atoms were constrained to the parent site, using a riding
model. The absolute structure of the noncentrosymmetric
complex 4 was determined using the Flack parameter 0.005-
(6).34 The coordinated hydride in 4 was located from the
difference Fourier map after anisotropic refinement, and then
Rea ction of [µ-Ir Cl(C8H14)2]2 w ith DP BE. F or m a tion of
[Ir HCl(DP BE)2] (9a ,b). THF (5 mL) was transferred to a
Schlenk tube containing [µ-IrCl(C8H14)2]2 (54.4 mg, 60.7 µmol),
resulting in an orange suspension. A solution of DPBE (74.4
mg, 0.243 mmol) in THF (5 mL) was transferred to the stirred
suspension, which instantly became clear. After a couple of
minutes the solution became light yellow and was stirred for
a further 30 min. Filtration removed traces of metallic iridium,
and the solution was reduced to ca. 2 mL. Addition of n-hexane
(20 mL) formed an off-white precipitate. The powder was
isolated, washed with additional n-hexane (2 × 15 mL), and
dried under vacuum. Yield: 88.8 mg (87%).1H NMR (C6D6): δ
3
8.37-6.49 (m, 56H, Ar), 7.54 (d, J PH ) 5.0 Hz, 1H, Ar-
CH(R)-Ir, 9b), 6.79 (d, 3J PH ) 7.4 Hz, 1H, Ar-CH(R)-Ir, 9a ),
5.41 (d, 2J HH ) 13 Hz, 1H, -CH2-, 9b), 5.01 (d, 2J HH ) 12 Hz,
1H, -CH2-, 9a ), 4.29 (d, 2J HH ) 13 Hz, 1H, -CH2-, 9b), 4.04
(31) Sheldrick; G. M. SADABS: Program for Absorption Correction;
University of Go¨ttingen, Go¨ttingen, Germany, 1996.
(32) Sheldrick; G. M. SHELXL-86: Structure Solution Program;
University of Go¨ttingen, Go¨ttingen, Germany, 1990.
(33) Sheldrick; G. M. SHELXL-93: Structure Refinement Program;
University of Go¨ttingen, Go¨ttingen, Germany, 1993.
(34) Flack, H. D. Acta Crystallogr. 1983, A39, 876.
2
(d, J HH ) 13 Hz, 1H, -CH2-, 9a ), 3.70 (s, 3H, -CH3, 9b),
3.29 (s, 3H, -CH3, 9b), 2.85 (s, 3H, -CH3, 9a ), 2.58 (s, 3H,
-CH3, 9a ), -19.8 (dd, 2J PH ) 21, 11 Hz, 1H, Ir-H, 9a ), -20.0
(t, 2J PH ) 16 Hz, 1H, Ir-H, 9b). 13C{1H} NMR (C6D6): δ 135-
2
126 (md, Ar), 91.4 (d, J PC ) 98 Hz, Ar-CH(R)-Ir), 79.8 (d,

C-H Activated Rh(III) and Ir(III) Complexes
Organometallics, Vol. 18, No. 11, 1999 2205
the hydride was isotropically refined. No high electron density
residues were found in the structures.
Su p p or tin g In for m a tion Ava ila ble: Tables of crystal
data and structure refinement, atomic coordinates, bond
lengths and angles, anisotropic displacement parameters, and
hydrogen coordinates for complexes 1 and 4 and a table of
least-squares planes for 1. This material is available free of
charge via the Internet at http://pubs.acs.org.
Ack n ow led gm en t. Financial support by the TFR
(The Swedish Research Council for Technological Sci-
ences) and the NFR (The Swedish Natural Science
Research Council) is gratefully acknowledged.
OM980929G