Stereochemical and electronic control of functionalized tripodal phosphines. Reactivity of the adamantane-type Ir(tripod) (CO)Cl (tripod = cis,cis-1,3,5-(PPh2)3-1,3,5-X3C 6H6; X = H, COOMe, CN) complexes toward H+, H2, CO, and C2H4

Article abstract of DOI:10.1021/om960006q

Treatment of the tripodal phosphine ligand cis,cis-1,3,5-tris(diphenylphosphino)-1,3,5-tris-(methoxycarbonyl)cyclohexane (tdppcyme) (2) with Ir(PPh₃)₂(CO)Cl gives the carbonyl chloro complex Ir(tdppcyme)(CO)Cl (2a). NMR spectroscopic investigations prove a dynamic equilibrium between a square-planar (2a′) and a trigonal-bipyramidal (2a) complex with two and three phosphine groups coordinated to iridium, respectively. This is in contrast to the comparable complexes Ir(tripod)(CO)Cl (1a, 3a) [tripod = cis,czs-1,3,5-tris(diphenylphosphino)cyclohexane (tdppcy) (1), cis,Cis-1,3,5-tricyano-cis,cis-1,3,5-tris(diphenylphosphino)-cyclohexane (tdppcycn) (3)] which only exist in the trigonal-bipyramidal form. The three compounds Ir(tripod)(CO)Cl (1a-3a), which only differ in the functionalization of the ligand backbone, display altered basicity and thus different reaction patterns. The carbonyl chloro complexes 1a-3a are readily protonated by the strong acid HBF₄ to give the octahedral cations 1b-3b. The weaker acid NH₄PF₆ is only able to protonate the most basic complex Ir(tdppcy)(CO)Cl (1a). While Ir(tdppcycn)(CO)Cl (3a) shows no reaction in the presence of NH₄PF₆, 2a is orthometalated to complex 2f′. The compounds Ir(tdppcy)(CO)Cl (1a) and Ir(tdppcycn)(CO)Cl (3a) oxidatively add H₂ with dissociation of Cl^- to yield the octahedral dihydrides [Ir(tripod)(CO)(H)₂]Cl (1c′, 3c′). Under the same conditions a phosphine arm dissociates from 2a to form the dihydride Ir(η²-tdppcyme)(CO)(H)₂Cl (2c′). In a CO atmosphere the Ir(tripod)(CO)Cl (1a-3a) complexes give the dicarbonyl derivatives [Ir-(tripod)(CO)₂]Cl (1d′-3d′). The dicarbonyls 2d′ and 3d′ are in an equilibrium with their starting materials. Replacement of the Cl^- by BPh₄^- allows the isolation of all three dicarbonyl complexes. Treatment of 1a-3a with ethylene in the presence Of NaBPh₄ gives the ethylene complexes [Ir(tripod)(CO)(C₂H₄)BPh₄ (1e-3e). Variable-temperature NMR studies show that there is an exchange process which equilibrates the equatorial with the apical phosphorus nuclei while the CO and ethylene ligands remain rigid. In the cases of 2e and 3e a second dynamic process with a low-energy barrier exists. Above 45 and 35 °C, respectively, 1e and 2e lose ethylene and are orthometalated to 1f and 2f. The cyclometalated products 1f and 2f can also be obtained by the direct reaction of 1a and 2a with NaBPh₄. For the dicarbonyl complex 3a and the orthometalated product 2f X-ray structure determinations have been performed.

Full text of DOI:10.1021/om960006q

Organometallics 1996, 15, 3393-3403
3393
Ster eoch em ica l a n d Electr on ic Con tr ol of F u n ction a lized
Tr ip od a l P h osp h in es. Rea ctivity of th e
Ad a m a n ta n e-Typ e Ir (tr ip od )(CO)Cl (tr ip od )
cis,cis-1,3,5-(P P h 2)3-1,3,5-X3C6H6; X ) H, COOMe, CN)
1
Com p lexes tow a r d H+, H2, CO, a n d C2H4
Philipp Sto¨ssel, Wolfgang Heins, Hermann A. Mayer,*,2 Riad Fawzi, and
Manfred Steimann
Institut fu¨r Anorganische Chemie, Auf der Morgenstelle 18, D-72076 Tu¨bingen, Germany
Received J anuary 3, 1996X
Treatment of the tripodal phosphine ligand cis,cis-1,3,5-tris(diphenylphosphino)-1,3,5-tris-
(methoxycarbonyl)cyclohexane (tdppcyme) (2) with Ir(PPh3)2(CO)Cl gives the carbonyl chloro
complex Ir(tdppcyme)(CO)Cl (2a ). NMR spectroscopic investigations prove a dynamic
equilibrium between a square-planar (2a ′) and a trigonal-bipyramidal (2a ) complex with
two and three phosphine groups coordinated to iridium, respectively. This is in contrast to
the comparable complexes Ir(tripod)(CO)Cl (1a , 3a ) [tripod ) cis,cis-1,3,5-tris(diphenylphos-
phino)cyclohexane (tdppcy) (1), cis,cis-1,3,5-tricyano-cis,cis-1,3,5-tris(diphenylphosphino)-
cyclohexane (tdppcycn) (3)] which only exist in the trigonal-bipyramidal form. The three
compounds Ir(tripod)(CO)Cl (1a -3a ), which only differ in the functionalization of the ligand
backbone, display altered basicity and thus different reaction patterns. The carbonyl chloro
complexes 1a -3a are readily protonated by the strong acid HBF4 to give the octahedral
cations 1b-3b. The weaker acid NH4PF6 is only able to protonate the most basic complex
Ir(tdppcy)(CO)Cl (1a ). While Ir(tdppcycn)(CO)Cl (3a ) shows no reaction in the presence of
NH4PF6, 2a is orthometalated to complex 2f′. The compounds Ir(tdppcy)(CO)Cl (1a ) and
Ir(tdppcycn)(CO)Cl (3a ) oxidatively add H2 with dissociation of Cl- to yield the octahedral
dihydrides [Ir(tripod)(CO)(H)2]Cl (1c′, 3c′). Under the same conditions a phosphine arm
dissociates from 2a to form the dihydride Ir(η2-tdppcyme)(CO)(H)2Cl (2c′). In a CO
atmosphere the Ir(tripod)(CO)Cl (1a -3a ) complexes give the dicarbonyl derivatives [Ir-
(tripod)(CO)2]Cl (1d ′-3d ′). The dicarbonyls 2d ′ and 3d ′ are in an equilibrium with their
starting materials. Replacement of the Cl- by BPh4 allows the isolation of all three
-
dicarbonyl complexes. Treatment of 1a -3a with ethylene in the presence of NaBPh4 gives
the ethylene complexes [Ir(tripod)(CO)(C2H4)]BPh4 (1e-3e). Variable-temperature NMR
studies show that there is an exchange process which equilibrates the equatorial with the
apical phosphorus nuclei while the CO and ethylene ligands remain rigid. In the cases of
2e and 3e a second dynamic process with a low-energy barrier exists. Above 45 and 35 °C,
respectively, 1e and 2e lose ethylene and are orthometalated to 1f and 2f. The cyclometalated
products 1f and 2f can also be obtained by the direct reaction of 1a and 2a with NaBPh4.
For the dicarbonyl complex 3a and the orthometalated product 2f X-ray structure determina-
tions have been performed.
In tr od u ction
In particular the interesting coordination chemistry
of branched tripodal phosphine ligands which are based
on the neopentyl backbone has attracted researchers for
many years.3a,b,6 In these ligand systems the stereo-
selective occupation of a triangular face of a coordination
Polyphosphines are popular ligands for chemical
control devices because their basicity and stereochem-
istry can be varied over a wide range.3 Some remark-
able chemical behavior can be developed from specially
designed polypodal phosphine ligands which impose
unusual coordination geometries on transition metal
complexes. A result of this is the important role of
polyphosphines in stoichiometric4 and in catalytic5
reactions.
(4) (a) Bianchini, C.; Caulton, K. G.; Folting, K.; Meli, A.; Peruzzini,
M.; Polo, A.; Vizza, F. J . Am. Chem. Soc. 1992, 114, 7290. (b) Bianchini,
C.; Barbaro, P.; Meli, A.; Peruzzini, M.; Vacca, A.; Vizza, F. Organo-
metallics 1993, 12, 2505. (c) Bianchini, C.; Caulton, K. G.; Chardon,
C.; Doublet, M.-L.; Eisenstein, O.; J ackson, S. A.; J ohnson, T. J .; Meli,
A.; Peruzzini, M.; Streib, W. E.; Vacca, A.; Vizza, F. Organometallics
1994, 13, 2010.
(5) (a) Meek, D. W. In Homogeneous Catalysis with Metal Phosphine
Complexes; Pignolet, L. H., Ed.; Plenum Press: New York, 1983; p 257.
(b) Bianchini, C.; Meli, A.; Peruzzini, M.; Vizza, F.; Zanobini, F. Coord.
Chem. Rev. 1992, 120, 193.
(6) (a) Di Vaira, M.; Sacconi, L. Angew. Chem., Int. Ed. Engl. 1982,
21, 330. (b) J anssen, B. C.; Sernau, V.; Huttner, G.; Asam, A.; Walter,
O.; Bu¨chner, M.; Zsolnai, L. Chem. Ber. 1995, 128, 63. (c) Heidel, H.;
Scherer, J .; Asam, A.; Huttner, G.; Walter, O.; Zsolnai, L. Chem. Ber.
1995, 128, 293.
X Abstract published in Advance ACS Abstracts, J une 15, 1996.
(1) Dedicated to Prof. Marianne Baudler on the occasion of her 75th
birthday.
(2) E-mail address: hermann.mayer@uni-tuebingen.de.
(3) (a) Mason, R.; Meek, D. W. Angew. Chem., Int. Ed. Engl. 1978,
17, 183. (b) Sacconi, L.; Mani, F. Transition Met. Chem. 1982, 8, 179.
(c) Cotton, F. A.; Hong, B. Prog. Inorg. Chem. 1992, 40, 179. (d) Mayer,
H. A.; Kaska, W. C. Chem. Rev. 1994, 94, 1239.
S0276-7333(96)00006-4 CCC: $12.00 © 1996 American Chemical Society
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3394 Organometallics, Vol. 15, No. 15, 1996
Sto¨ssel et al.
Ch a r t 1
Sch em e 1
polyhedron allows assembly of the participating ligands
exclusively in cis-positions.7 This is a requirement for
transformations of substrates in the coordination sphere
of a metal center.8
The advantage of polypodal phosphine complexes over
their monodentate counterparts has been outlined
earlier.3a Thus the increased thermal stability of metal
complexes stabilized by tripodal phosphine ligands has
allowed the use of those phosphine complexes in cata-
lytic processes which require drastic reaction condi-
tions.9
Sch em e 2
We have recently reported on the preparation of new
tripodal phosphine ligands with three diphenylphos-
phine groups stereospecifically bound cis,cis to the 1,3,5
positions of the cyclohexane ring (Chart 1).10 A conse-
quence of the specific coordination behavior of these
ligands is a metal template adamantane-type poly-
hedron with rigid stereochemistry and stoichiometry
control of the resulting metal complexes. The op-
portunity to add other functional groups at the ipso
positions of the cyclohexane ring10b,c offers the advan-
tages of (i) improvement of the synthesis, (ii) control of
the electron density at the metal center, (iii) control of
the solubility, and (iv) use of the groups as spacers to
support the metal complexes.10c
Here we wish to report on the reactivity of the
adamantane-type complexes Ir(tripod)(CO)Cl [tripod )
cis,cis-1,3,5-tris(diphenylphosphino)cyclohexane (tdp-
pcy) (1), cis,cis-1,3,5-tris(diphenylphosphino)-1,3,5-tris-
(methoxycarbonyl)cyclohexane (tdppcyme) (2), and cis,cis-
1,3,5-tricyano-cis,cis-1,3,5-tris(diphenylphosphino)-
cyclohexane (tdppcycn) (3)] (Chart 1) with acids and the
small molecules H2, CO, and C2H4.
ligand tdppcyme (2) (Chart 1) and Ir(PPh3)2(CO)Cl are
heated in toluene (Scheme 1).
Compound 2a is air-sensitive in the solid state and
in solution. Like 1a 10a (Scheme 2) Ir(tdppcyme)(CO)Cl
(2a ) dissolves in chlorinated solvents and is sensitive
to light in these solutions. In contrast to 1a and Ir-
(tdppcycn)(CO)Cl10c (3a ) (Scheme 2) two ν(CO) absorp-
tions are observed in the carbonyl region of the IR
spectrum of 2a . In solution (IR/CH2Cl2, ν(CO) ) 2006,
1931 cm-1) the relative intensity ratio of 1:15 remains
constant while in the solid state (IR/KBr ν(CO) ) 2008,
1928 cm-1) altered intensity ratios of 1:1 to 1:10 are
found in different batches. A comparison of the ob-
served carbonyl absorption frequencies of 2a with those
of structurally related complexes Ir(tdppcy)(CO)Cl10a (1a )
(ν(CO) ) 1912 cm-1), Ir(tdpme)(CO)Cl11 (ν(CO) ) 1900
cm-1), Rh(tdpme)(CO)Cl11 (ν(CO) ) 2005 and 1915 cm-1),
and Rh(dppe)(CO)Cl12 (ν(CO) ) 2010 cm-1) (tdpme )
1,1,1-tris[(diphenylphosphino)methyl]ethane, dppe )
Resu lts a n d Discu ssion
Syn th esis an d Ch ar acter ization of Ir (tdppcym e)-
(CO)Cl (2a ,a ′). The orange carbonyl chloro complex 2a
is obtained when the potentially tripodal phosphine
(7) (a) J ohnston, G. G.; Baird, M. C. Organometallics 1989, 8, 1894.
(b) Barbaro, P. L.; Bianchini, C.; Meli, A.; Peruzzini, M.; Vacca, A.;
Vizza, F. Organometallics 1991, 10, 2227.
(8) Collman, J . P.; Hegedus, L. S.; Norton, J . R.; Finke, R. G.
Principles and Applications of Organotransition Metal Chemistry;
University Science Books: Mill Valley, CA, 1987.
(9) (a) Bianchini, C.; Meli, A.; Peruzzini, M.; Vizza, F.; Frediani, P.;
Herrera, V.; Sa´nchez-Delgado, R. A. J . Am. Chem. Soc. 1993, 115, 7505.
(b) Bianchini, C.; Meli, A.; Peruzzini, M.; Vizza, F.; Moneti, S.; Herrera,
V.; Sa´nchez-Delgado, R. A. J . Am. Chem. Soc. 1994, 116, 4370. (c)
Bianchini, C.; J ime´nez, M. V.; Meli, A.; Vizza, F.; Moneti, S.; Herrera,
V.; Sa´nchez-Delgado, R. A. Organometallics 1995, 14, 2342.
(10) (a) Mayer, H. A.; Otto, H.; Ku¨hbauch, H.; Fawzi, R.; Steimann,
M. J . Organomet. Chem. 1994, 472, 347. (b) Mayer, H. A.; Sto¨ssel, P.;
Fawzi, R.; Steimann, M. J . Organomet. Chem. 1995, 492, C1. (c) Mayer,
H. A.; Sto¨ssel, P.; Fawzi, R.; Steimann, M. Chem. Ber. 1995, 128, 719.
(11) Siegl, W. O.; Lapporte, S. J .; Collman, J . P. Inorg. Chem. 1971,
10, 2158.
(12) Hieber, W.; Kummer, R. Chem. Ber. 1967, 100, 148.
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Functionalized Tripodal Phosphines
Organometallics, Vol. 15, No. 15, 1996 3395
Ta ble 1. Selected 1H, 31P , a n d IR Da ta for Com p lexes 1a -f, 2a -f, 3a -e, a n d 2c′
1H (ppm)a for
hydride/ethylene
compd
31P{1H} (ppm)a
ν(IrH)/ν(CO) (cm-1) (KBr)
1a
2a
3a
1b
2b
3b
1c
2c
2c′
3c
1d
2d
3d
1e
2e
3e
1f
-14.1
-/1912
5.4
-/2006, 1928 (2008, 1931)b
-/1928-1951 (1956)c
2144/2081
2137/2091
2168/2107
2092/2047
-/2062
-3.5
-8.37/-
-34.9, -27.9, -11.8
-18.2, -11.4, -4.2
-23.0, -14.4, -7.1
-23.8, -15.6
-9.0, -4.1
-9.08/-
-8.53/-
-10.20/-
-10.25/-
-10.42, -8.89/-
-8.57/-
17.3, 18.0, 28.0
-9.8, 7.8
2105, 2049/2007
-/2088
-/2039, 1961
-/2049, 1982
-/2064, 1998
-/2025
-/2043
-/2055
2077/2025
2086/2048
-21.8
-5.3
-10.3
-/2.8, 2.0 (N ) 4.0 Hz)
-/2.5, 2.1 (N ) 7.9 Hz)
-/2.9, 2.4 (N ) 7.6 Hz)
-7.81/-
-27.6, -32.3d
-13.8, -18.7e
-17.3, -25.8f
-90.6, -30.5, -25.6
-81.7, -9.4, -6.2
2f
-8.48/-
a
b
d
2
The multiplicities and coupling constants are given in the Experimental Section. In CH2Cl2. c In CHCl3. -68 °C, d, t, J PP ) 32.9
Hz. e -26 °C, d, t, J PP ) 33.5 Hz. f -68 °C, d, t, J PP ) 34.1 Hz.
2
2
1,2-bis(diphenylphosphino)ethane) leads to the conclu-
sion that in solution as well as in the solid state two
coordination isomers exist (Scheme 1). The carbonyl
absorption with lower energy is assigned to isomer
2a .10a,c,11 In 2a ′ only two phosphine groups are bound to
the coordination center while the third remains non-
bonded. The steric constraints of the ligand backbone
in tdppcyme (2) generate a cis square-planar environ-
ment around iridium with the carbonyl located trans
to a phosphine group. Consequently the ν(CO) absorp-
tion in 2a ′ is observed at higher frequencies.12
decrease in the electron-donating ability of the func-
tionalized phosphine ligands tdppcy (1) > tdppcyme (2)
> tdppcycn (3). This implies an altered basicity and
reactivity of the three complexes which is outlined as
follows.
Rea ctivity of Ir (tr ip od )(CO)Cl tow a r d Acid s.
When the chloro carbonyl complexes 1a -3a are treated
with an excess of HBF4 in dichloromethane, they are
readily protonated to give the octahedral cationic mono-
hydrides 1b-3b (Scheme 2). If the same reaction is
repeated with the weak acid NH4PF6, only 1a is basic
enough to be protonated under the formation of the
cation 1b′ (Scheme 2). The basicity of the functionalized
complexes 2a and 3a is too weak to deprotonate the
The 31P{1H} NMR spectrum (161.98 MHz) of 2a and
2a ′ at room temperature displays only a broad reso-
nance (ν1/2 ) 25 Hz) at δ 5.4. Upon warming of the
sample, the peak continues broadening until at 40°C
the resonance coalesces into the baseline. When the
temperature is lowered to -10 °C the signal becomes
sharp (ν1/2 ) 5 Hz). Further cooling does not change
the line width until below -30 °C the resonance starts
to broaden again. At the lowest accessible temperature
(-100 °C) the line width of the peak is ν1/2 > 40 Hz.
The line broadening above -10 °C is consistent with a
fast equilibrium which includes dissociation and as-
sociation of one phosphine arm from the metal center
(Scheme 1). As the temperature is lowered, the equi-
librium is shifted toward the isomer 2a . Such penta-
coordinated metal complexes are stereochemically
nonrigid.10a,c,13 A fast exchange process between the
different phosphorus sites accounts for the observation
of only one sharp singlet in the temperature range of
-10 to -30 °C. At lower temperatures the exchange
process is slowed down as indicated by line broadening;
however, decoalescence is not observed. Solid-state
NMR spectroscopy at room temperature does not allow
to distinguish between the equilibrium of 2a a 2a ′ and
the high fluxionality of the molecule. One broad singlet
and one set of carbon resonances consistent with a C3
symmetry of the [Ir(tdppcyme)] template in the 31P and
13C CP/MAS NMR spectrum, respectively, are detected.
The increased carbonyl stretching frequencies of the
carbonyl chloro complexes 1a -3a (Table 1) indicate a
+
NH4 cation. Although no reaction is observed with
Ir(tdppcycn)(CO)Cl (3a ), replacement of the coordinating
anion Cl- of Ir(tdppcyme)(CO)Cl (2a ) with the non-
coordinating PF6- gives intramolecular C-H activation.
The final orthometalated product 2f ′ (Scheme 2) can also
be obtained by different methods which are discussed
below.
In the 31P{1H} NMR spectra each compound gives rise
to three doublets of doublets in the range of -4 to -35
2
(Table 1). The J PP coupling constants between 10.0 to
24.3 Hz are characteristic for the cis arrangements of
1
the phosphine groups. The H NMR spectra of 1b-3b
and 1b′ display multiplet patterns (δ -8.37 to -9.08)
which are the result of one large coupling of the hydride
resonance to one phosphine group trans and smaller
splittings by two phosphine groups cis to the hydride.
The additional interaction (4J HH ) 1.9 Hz) which is
observed for the hydride with the C-H proton of the
cyclohexane ring in the cases of 1b and 1b′ is indicative
of a rigid ligand backbone.
Rea ctivity of Ir (tr ip od )(CO)Cl tow a r d H2. The
carbonyl chloro complexes 1a -3a react with hydrogen
in different ways. When Ir(tdppcy)(CO)Cl (1a) is treated
with H2 in dichloromethane, the octahedral dihydride
complex 1c′ is obtained quantitatively within 24 h. The
oxidative addition of H2 forces the chlorine to dissociate
from the metal center irreversibly (Scheme 3). Under
the same reaction conditions 3a forms an equilibrium
with 3c′ with the equilibrium lying on the left side. The
dihydride complex 3c′ cannot be isolated. Addition of
(13) (a) Wood, J . S. Prog. Inorg. Chem. 1972, 16, 227. (b) Holmes,
R. W. Prog. Inorg. Chem. 1984, 32, 119. (c) Dahlenburg, L.; Mirzaei,
F. Inorg. Chim. Acta 1985, 97, L1.
+
+

3396 Organometallics, Vol. 15, No. 15, 1996
Sto¨ssel et al.
Sch em e 3
Sch em e 4
chemical assignment is based on solution NMR and IR
spectroscopy under H2 atmosphere and confirms the
structure displayed in Scheme 3. The dihydride com-
plex 2c′ contains two different hydride resonances in
the 1H NMR spectrum. One resonance (δ -10.42) shows
both cis- (2J PH ) 19.3 Hz) and trans-phosphorus cou-
pling (2J PH ) 155.4 Hz). The chemical shift of the
hydride resonance (δ -8.89) which shows only cis-
phosphorus coupling (2J PH ) 17.0 Hz) is typical for a
hydride trans to CO. Both hydrides weakly (2J HH < 0.5
Hz) interact with each other. The three different
environments for the phosphorus groups account for
three signals in the 31P{1H} NMR spectrum. The
resonances of the phosphorus nuclei trans to the hydride
(δ 17.3) and trans to the chlorine (δ 28.0) are split by
each other (2J PP ) 9.8 Hz) while the noncoordinated
phosphine group gives a singlet at δ 18.0.
NaBPh4 to the reaction mixture substitutes the Cl-
anion with BPh4- and gradually shifts the equilibrium
to the right. Because of the weak basicity of Ir-
(tdppcycn)(CO)Cl (3a ) the reaction takes 2-3 weeks for
completion. In contrast to 1a and 3a the reversible
oxidative addition to the ester-functionalized complex
2a is completed within 5-10 min (Scheme 3). The fact
that in 2c′ only two phosphine groups are bound to
iridium suggests that 2a ′ is the actual starting com-
pound (Scheme 1). The stereochemistry of the reaction
of H2 with 2a ′ to 2c′ is consistent with the kinetic
controlled product of the comparable reaction with the
cis-Ir(dppe)(CO)Cl complex.14 The reaction of 2a with
H2 in the presence of NaBPh4 leads to the dihydride
complex 2c with all three phosphine groups coordinated
to the metal (Scheme 3) which is isostructural to 1c and
3c.
In the IR spectrum of 2c′ the two ν(IrH) absorptions
appear at 2105 and 2049 cm-1 and are characteristic
for hydrogen trans to strong trans influencing ligands.15
As expected for octahedral Ir(III) complexes ν(CO) is
shifted to higher frequencies (2007 cm-1).
R ea ct ion of t h e Ir (t r ip od )(CO)Cl Com p lexes
w ith CO. The altered basicity of the three functional-
ized carbonyl chloro complexes is also reflected in the
gradation of their affinity toward the π-acid CO (Scheme
4). Thus the dicarbonyl complex 1d ′ can be isolated in
quantitative yield by treatment of 1a -3a with CO but
the corresponding complex [Ir(tdppcyme)(CO)2]Cl (2d ′)
can only be obtained and characterized under a CO
atmosphere. The weakest base in this series 3a hardly
reacts with CO to give 3d ′, which is only identified on
the basis of its 31P{1H} NMR and IR spectra. Although
the formation of 1d ′ is irreversible, removal of the CO
atmosphere causes the decomposition of 2d ′ and 3d ′ to
the starting materials (Scheme 4). When the reactions
of 1a -3a with CO are repeated in the presence of
NaBPh4, the cationic dicarbonyl complexes 1d -3d are
generated in high yields. Due to the weak electron-
donating ability of 3a the reaction rate is low which
leads to a prolonged reaction time of 4 days. In contrast,
the conversion of 1a and 2a to 1d and 2d is complete
within 15 h.
In the 31P{1H} NMR spectra of 1c-3c the two
phosphine groups trans to the hydrogen ligands are
observed as doublets at a higher field than the triplets
of the phosphine groups coordinated trans to CO. This
is in agreement with the stronger trans influence of the
hydride compared to CO. The hydride regions in the
1H NMR spectra of 1c-3c display the AA′ parts of
AA′MXX′ spin systems which are typical for two chemi-
cally but not magnetically equivalent hydride ligands
(Table 1).4b
Since the labile dihydride complex 2c′ can only be
isolated in pure form under H2 atmosphere, its stereo-
(14) (a) Fisher, B. J .; Eisenberg, R. Inorg. Chem. 1984, 23, 3216.
(b) J ohnson, C. J .; Fisher, B. J .; Eisenberg, R. J . Am. Chem. Soc. 1983,
105, 7772. (c) J ohnson, C. R.; Eisenberg, R. J . Am. Chem. Soc. 1985,
107, 3148. (d) Fisher, B. J .; Eisenberg, R. Organometallics 1983, 2,
764.
The singlets observed in the 31P{1H} NMR spectra in
the region of δ -21.9 to -5.3 (Table 1) are in agreement
(15) Vaska, L. J . Am. Chem. Soc. 1966, 88, 4100.
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Functionalized Tripodal Phosphines
Organometallics, Vol. 15, No. 15, 1996 3397
Sch em e 5
F igu r e 1. Variable-temperature 31P{1H} NMR spectra of
[Ir(tdppcy)(CO)(C2H4)]+ (1e) (161.98 MHz).
with high fluxionality which exchanges the different
environments of the phosphorus sites and that of the
carbonyl groups. This is confirmed by the 13C{1H} NMR
spectra of 1d -3d . In the carbonyl region of each
dicarbonyl complex a quartet at δ 180.8 (1d ), 178.2 (2d ),
and 175.6 (3d ), respectively, with weighted averaged cis
and trans 2J PC coupling constants demonstrate the high
flexibility. The increase in deshielding from 3d < 2d
< 1d is also consistent with the increased electron
density at the metal center and thus with better M-CO
back-bonding.16 This is further supported by the IR
spectra of 1d -3d . The two ν(CO) absorptions observed
for each compound are shifted to higher frequencies in
the order 1d < 2d < 3d (Table 1).
(2e), 27.0 (3e)]. The observation of two ethylene hy-
drogen types but a single ethylene carbon chemical shift
suggests a Cs symmetry for the ethylene complexes 1e-
3e (Scheme 5). This is consistent with the planar
equatorial positioning of the ethylene ligand and two
of the phosphine groups as shown for 1e-3e in Scheme
5.17
In contrast to the inflexible ethylene ligand the NMR
data for the tripodal phosphine backbone are in agree-
ment with high fluxionality of the [Ir(tripod)] fragment.
Thus a single set of multiplets (1e) and ABX2 (2e, 3e)
patterns for the six ring methylene protons and unique
carbon resonances of the ligand backbone are observed
R ea ct ion of t h e Ir (t r ip od )(CO)Cl Com p lexes
w ith Eth ylen e. Addition of excess ethylene and NaB-
Ph4 to 1a -3a in dichloromethane gives the cationic
ethylene complexes 1e-3e in high yields (Scheme 5).
Again the different basicity of the starting complexes
is mirrored in the extent of the reaction times (6 h for
1e, 10 h for 2e, and 10 d for 3e). The ethylene
complexes are stable in the solid state and can be stored
in an oxygen free atmosphere. When solutions of [Ir-
(tripod)(CO)(C2H4)]BPh4 are heated above 45 °C (1e),
35 °C (2e), and 68 °C (3e), respectively, the complexes
decompose with loss of ethylene. In the cases of 1e and
2e the orthometalated complexes 1f and 2f are observed
as the major decomposition products (see below) (Scheme
5).
1
in the H and 13C{1H} NMR spectra at room tempera-
ture, respectively. Further support for a dynamic
process which equilibrates the equatorial and apical
positions of the ligand backbone in 1e-3e stems from
31P{1H} NMR investigations at variable temperatures
(Figures 1 and 2). The broad unresolved resonances at
δ -27.1 (1e), -13.8 (2e), and -19.1 (3e), which are
found at room temperature already indicate that the
exchange process is slow. When the temperature is
lowered, the coalescence point is reached at 5 °C (1e),
10 °C (2e), and 2 °C (3e), respectively. Further cooling
of the samples reveals the separation of two signals (2:
1) from the base line until at -68 °C (1e), -26 °C (2e),
and -56 °C (3e), respectively, a doublet and a triplet
for each compound is fully resolved (Figures 1 and 2;
Table 1). The AX2 spin patterns correspond to the
trigonal-bipyramidal structures shown in Scheme 5.
While in the case of the tdppcy ligand this is the limiting
spectrum which is obtained as low as -102 °C, a second
dynamic process with a lower energy barrier is found
for the complexes 2e and 3e. At temperatures below
-40 °C in the case of 2e and -70 °C for the CN-
functionalized complex 3e, the doublets which are due
to the two equatorial phosphine groups first broaden
and then coalesce [-85 °C (2e), -102 °C (3e)]. The
triplet caused by the phosphorus nuclei trans to the
1
In the H NMR spectra of 1e-3e the four ethylene
hydrogens give rise to AA′XX′ patterns which are
slightly broadened by additional interactions with the
phosphorus nuclei (Table 1). The chemical shifts of the
ethylene multiplets are basically invariant to changes
in temperature from -100 to 45 °C (1e), -40 to 35 °C
(2e), and -70 to 68 °C (3e), respectively, and indicate
that the two different environments for the hydrogen
atoms do not change over this temperature range. Upon
coordination of ethylene to the [Ir(tripod)(CO)]+ frag-
ments, the 13C resonances of the ethylene groups are
shifted dramatically to higher field [δ 20.1 (1e), 25.8
(16) Mason, J . Multinuclear NMR; Plenum Press: New York, 1987;
p 73.
(17) Rossi, A. R.; Hoffmann R. Inorg. Chem. 1975, 14, 365.
+
+

3398 Organometallics, Vol. 15, No. 15, 1996
Sto¨ssel et al.
Ch a r t 2
complexes does not occur via a P-M dissociation
process, since the activation energy for a phosphorus
arm dissociation greatly exceeds that of the fluxionality.
This is also consistent with the observation of phospho-
rus-phosphorus coupling which excludes a dissociation
of a phosphine arm from iridium as well.20 The stereo-
chemical constraints of the backbone of the tripodal
phosphine ligands prohibit a Berry pseudorotation so
that a turnstile mechanism becomes operative.13a,b,21
Or th om eta la tion of th e Ir (tr ip od )(CO)Cl Com -
p lexes. The dissociation of Cl- from the Ir(tripod)(CO)-
Cl complexes 1a -3a leads to d8 ML4 fragments of
angular geometry as shown in Chart 2.22 The steric
compression of the tripod ligands 1-3 (Chart 1) imposes
a facial coordination on the d8 metal which is highly
unstable compared to square-planar d8 ML4 com-
plexes.23 The frontier orbital set of such an angular ML4
fragment is highly favorable for C-H bond activation.24
Besides this steric demand a high basicity of the metal
fragment is required to donate electron density into the
antibonding orbital of the C-H.22,24 This is nicely
demonstrated by the [Ir(tripod)(CO)]+ fragments which
are of different basicity. Treatment of the carbonyl
chloro complexes 1a and 2a with NaBPh4 generates the
reactive angular fragments by replacing the chlorine
with the noncoordinating anion BPh4- and finally gives
the orthometalated complexes 1f and 2f (Scheme 5). The
reactive d8 ML4 intermediates can also be obtained by
the thermal dissociation of the weakly bound ethylene
ligand (Scheme 5). Due to the weak electron-donating
ability of tdppcycn (3), no orthometalation is observed
when either Ir(tdppcycn)(CO)Cl (3a ) is reacted with
NaBPh4 or [Ir(tdppcycn)(CO)(C2H4)]+ (3e) is heated (see
above).
F igu r e 2. Variable-temperature 31P{1H} NMR spectra of
[Ir(tdppcyme)(CO)(C2H4)]+ (2e) (161.98 MHz).
carbonyl remains sharp. A completely distorted mol-
ecule for 2e is indicated by two broad unresolved signals
at δ -13.1 and -16.8, which are observed besides the
triplet resonance due to the phosphorus nucleus trans
to CO at -99 °C. This second low-barrier process which
is only observed for the functionalized ethylene com-
plexes 2e and 3e may be attributed to sterical hindrance
of the phenyl rings at the phosphine groups and the
functional groups at the ligand backbone, although
electronic reasons cannot be excluded at this point.
The temperature-dependent 13C{1H} NMR spectra
follow the same trend. The carbon signals of the ligand
backbone first broaden, then coalesce, and finally split
into two sets of resonances in a 2:1 intensity ratio at
temperatures corresponding to the 31P{1H} NMR spec-
tra. Limiting spectra for the lower exchange process
in the cases of 2e and 3e could not be obtained. In
The intramolecular oxidative addition of a phenyl
C-H bond to the [Ir(tripod)(CO)]+ fragments results in
the formation of four-membered rings which reduce the
symmetry of the octahedral complexes 1f and 2f. Thus
the 31P{1H} NMR spectra of 1f and 2f display three
doublets of doublets (cis 2J PP between 16.3 and 27.8 Hz)
consistent with three phosphorus atoms in different
environments (Table 1). The dramatic high-field shift
[δ -90.6 (1f), -81.7 (2f)] which is observed for one of
the signals in each spectrum is typical for phosphorus
nuclei incorporated into four-membered rings.25 The
1
conformation with the H NMR data the singlet of the
ethylene carbon resonance remains sharp for 1e. How-
ever, it first broadens and then coalesces into the
baseline below -40 °C for [Ir(tdppcyme)(CO)(C2H4)]+
(2e) and -70 °C for [Ir(tdppcycn)(CO)(C2H4)]+ (3e),
respectively.
The NMR data clearly demonstrate that the three
carbonyl ethylene complexes 1e-3e belong to the small
group of pentacoordinate transition metal complexes
where the fluxional process is restricted to the tripodal
ligand backbone and does not involve the ethylene
ligand.18 This is in contrast to pentacoordinate carbonyl
ethylene complexes in which the ethylene rotation is
coupled with a Berry pseudorotation of the carbonyl
groups.19 The fluxionality of the [Ir(tripod)(CO)(C2H4)]+
1
characteristic features in the H NMR spectra of 1f and
(20) J esson, J . P.; Muetterties, E. L. In Dynamic Nuclear Magnetic
Resonance Spectroscopy; J ackman, L. M., Cotton, F. A., Eds.; Academic
Press: New York, 1975; p 253.
(21) Ugi, I.; Marquarding, D.; Klusacek, H.; Gillespie, P. Acc. Chem.
Res. 1971, 4, 288.
(22) Saillard, J .-Y.; Hofmann, R. J . Am. Chem. Soc. 1984, 106, 2006.
(23) Yamamoto, A. Organotransition Metal Chemistry; J ohn Wiley
& Sons: New York, 1986.
(18) Bianchini, C.; Meli, A.; Peruzzini, M.; Vizza, F.; Frediani, P.;
Ramirez, J . A. Organometallics 1990, 9, 226.
(19) (a) Kruczynski, L.; LiShingMan, L. K. K.; Takats, J . J . Am.
Chem. Soc. 1974, 69, 4006. (b) Wilson, T. S.; Coville, N. J .; Shapley, J .
R.; Osborn, J . A. J . Am. Chem. Soc. 1974, 96, 4038. (c) Faller, J . W.
Adv. Organomet. Chem. 1978, 16, 211. (d) Albright, T. A. Acc. Chem.
Res. 1982, 15, 149.
(24) Saillard, J .-Y. In Selective Hydrocarbon Activation Principles
and Progress; Davies, J . A., Watson, P. L., Liebman, J . F., Greenberg,
A., Eds.; VCH Publishers, Inc.: New York, 1990; p 207.
(25) (a) Garrou, P. E. Chem. Rev. 1981, 81, 229. (b) Lindner, E.;
Fawzi, R.; Mayer, H. A.; Eichele, K.; Pohmer, K. Inorg. Chem. 1991,
30, 1102. (c) Lindner, E.; Fawzi, R.; Mayer, H. A.; Eichele, K.; Hiller,
W. Organometallics 1992, 11, 1033.
+
+

Functionalized Tripodal Phosphines
Organometallics, Vol. 15, No. 15, 1996 3399
centers. In the trigonal-bipyramidal complex 3d the
three diphenylphosphine groups take up two equatorial
and one apical position. The coordination sphere is
completed by the two carbonyl ligands at an equatorial
and an apical site, respectively. The angle between the
equatorial phosphine groups P(1)-Ir-P(3) (97.2°)
strongly deviates from the ideal geometry (120°). This
is the largest angle found so far in a series of comparable
complexes Ir(tdppcycn)(CO)Cl (3a ) (95.9°),10c Ir(tdpme)-
(CO)Cl (90.3°),27 and Rh(tdpme)(CO)Me (90.8°).28 The
P(1)-Ir-C(71) angle (118.3°) remains close to ideal,
whereas the reduction of the angle between P(1) and
P(3) particularly affects the P(3)-Ir-C(71) angle which
opens to 144.7°. The overall sum of 359.9° demonstrates
that the equatorial plane is not distorted. The strong
trans influence of CO causes a weakening of the Paxial
-
metal bond which is expressed in a longer Paxial-metal
distance than that found in Ir(tdppcycn)(CO)Cl (3a ).
This makes the three Ir-P distances in [Ir(tdppcycn)-
(CO)2]+ (3d ) equivalent.
F igu r e 3. ORTEP drawing and atom-labeling scheme for
[Ir(tdppcycn)(CO)2]+ (3d ). Only the ipso-carbon atoms of
the phenyl rings are shown for clarity.
The geometry around Ir in the orthometalated com-
plex 2f is best described as distorted octahedral (Figure
4). The CO group, the R-carbon atom of the metalated
phenyl ring, and the hydride (could not be located from
a difference map) occupy the face trans to the tdppcyme
(2) ligand. The P-Ir-P angles fall within the range of
92.56(5)-95.24(5)°. The small angle of 162.7(2)° found
for P(2)-Ir-C(73) indicates that the CO group is bent
toward the hydride. It is noteworthy that a phenyl ring
of the phosphine group trans to the CO group is
metalated. This supports the assumption of an angular
d8 ML4 fragment (Chart 2) as a reactive intermediate.
The formation of the four-membered ring causes only
slight deformations of the orthometalated ring. The
benzene and the metalaphosphacyclobutane ring show
only small deviations from planarity (overall sum of the
endocyclic bond angles: 719.9 and 358.0°) with reduced
puckering of the four-membered ring which is charac-
teristic for orthometalated complexes.29
F igu r e 4. ORTEP drawing and atom-labeling scheme for
the orthometalated complex 2f. Only the ipso-carbon atoms
of the phenyl rings are shown for clarity.
Con clu sion
A characteristic feature of the recently introduced
functionalized tripodal phosphine ligands 1-3 is their
different electron-donating ability to metal complexes
which results in an altered basicity of the [Ir(tripod)]
template. This is nicely demonstrated by the carbonyl
stretching frequencies in the IR spectra of the com-
pounds discussed in this work (Table 1). In all cases
ν(CO) increases in the series of the iridium templates
[Ir(tdppcy)] < [Ir(tdppcyme)] < [Ir(tdppcycn)] (Table 1).
This is consistent with the protonation reactions, the
reaction rates with CO, and the formation of the
ethylene complexes. However, the reaction pattern
cannot be explained in terms of the electronic effect
alone. A more complex combination of electronic effects
and steric requirements accounts for the dissociation of
a phosphine arm from Ir(tdppcyme)(CO)Cl (2a ), which
was not observed for 1a and 3a , and for the different
dynamic behavior of the ethylene complexes 1e-3e.
2f are the hydride resonances at δ -7.81 and -8.48,
respectively. Both signals are split by one strong trans
and two weak cis interactions with the phosphorus
nuclei. Like in 1b and 1b′ the hydride peak of 1f shows
an additional splitting due to a C-H proton of the
cyclohexane ring. Mass spectra and elemental analysis
are also in agreement with an intramolecular oxidative
addition of a C-H bond which is thermodynamically
favored over the intermolecular metalation.26
X-r a y Str u ctu r e An a lysis. In order to get a better
insight into the constraints of the [Ir(tripod)] template
in different coordination geometries, X-ray diffraction
studies were undertaken on appropriate crystals of a
trigonal-bipyramidal (3d ) and an orthometalated (2f)
complex. The perspective views of 3d and 2f are
presented in Figures 3 and 4, respectively. Selected
bond lengths and bond angles are collected in Table 2
for both compounds.
As seen in Figure 3 and 4 the tdppcyme (2) and
tdppcycn (3) ligands are facially coordinated to the metal
(27) J anser, P.; Venanzi, L. M.; Bachechi, F. J . Organomet. Chem.
1985, 269, 229.
(28) Thaler, F. G.; Folding. K.; Caulton, K. G. J . Am. Chem. Soc.
1990, 112, 2664.
(26) (a) Omae, I. Chem. Rev. 1979, 79, 287. (b) Halpern, J . Inorg.
Chim. Acta 1985, 100, 41.
(29) Andreucci, L.; Diversi, P.; Ingrosso, G.; Lucherini, A.; Marchetti,
F.; Adovasio, V.; Nardelli, M. J . Chem. Soc., Dalton Trans. 1986, 803.
+
+

3400 Organometallics, Vol. 15, No. 15, 1996
Ta ble 2. Selected Bon d Dista n ces (Å) a n d An gles (d eg) for th e Com p lexes 3d a n d 2f
Sto¨ssel et al.
3d
2f
3d
2f
Ir-P(1)
2.365(2)
2.360(2)
2.362(2)
2.3870(14)
2.329(2)
2.3485(14)
2.140(5)
P(1)-Ir-P(3)
97.22(7)
93.46(7)
89.02(8)
95.24(5)
92.77(5)
92.56(5)
86.65(14)
93.8(2)
Ir-P(2)
P(1)-Ir-P(2)
Ir-P(3)
P(3)-Ir-P(2)
Ir-C(23)
P(1)-Ir-C(23)
P(1)-Ir-C(73)
P(1)-Ir-C(71)
P(1)-Ir-C(70)
P(2)-Ir-C(73)
P(2)-Ir-C(71)
P(2)-Ir-C(70)
C(23)-Ir-C(73)
C(71)-Ir-C(70)
P(3)-Ir-C(70)
P(3)-Ir-C(71)
P(2)-Ir-C(23)
Ir-C(23)-C(24)
C(23)-C(24)-P(2)
C(24)-P(2)-Ir
C(25)-C(26)-C(27)
C(29)-C(30)-C(25)
C(27)-C(28)-C(29)
C(3)-C(2)-C(1)
C(3)-C(4)-C(5)
C(5)-C(6)-C(1)
Ir-C(71)
1.860(10)
1.901(12)
Ir-C(70)
118.0(3)
96.5(3)
Ir-C(73)
1.902(7)
C(70)-O(1)
C(71)-O(2)
C(73)-O(7)
P(1)-C(1)
P(2)-C(3)
P(3)-C(5)
P(1)-C(25)
P(2)-C(27)
P(3)-C(29)
P(2)-C(24)
1.168(14)
1.169(13)
162.7(2)
98.6(3)
88.3(3)
169.9(3)
1.116(7)
1.881(5)
1.835(6)
1.917(5)
85.4(4)
91.5(3)
144.7(3)
1.888(8)
1.884(8)
1.900(8)
65.9(2)
106.2(4)
98.5(4)
87.4(2)
1.790(6)
117.0(7)
118.2(7)
115.2(6)
117.4(5)
117.7(4)
117.4(4)
performed using a Carlo Erba Model 1106 elemental analyzer.
Conductivities were measured on a Model DIGI 610 WTW
connected to a LTA/S conducting cell. The conductivity data
were obtained at sample concentrations of 1 mmol in dichlo-
romethane solutions at room temperature. Single-crystal
X-ray structure determinations of 3d and 2f were carried out
on a Siemens P4 diffractometer.
Further investigations for a better understanding of
these effects in order to improve control of reactivity and
selectivity in stoichiometric reactions as well as in
catalysis are in progress.
Exp er im en ta l Section
Ca r bon ylch lor o[cis,cis-1,3,5-tr is(d ip h en ylp h osp h in o)-
1,3,5-tr is(m eth oxyca r bon yl)cycloh exa n e]ir id iu m (I) (2a ).
A suspension of 2 (405.4 mg, 0.5 mmol) and Ir(PPh3)2(CO)Cl
(390.1 mg, 0.5 mmol) in 20 mL of toluene was heated at 80 °C
for 2 h, during which time an orange precipitate was formed.
This was collected on a sintered glass frit, washed twice with
10 mL of toluene each and three times with 10 mL of
n-pentane each, and dried in vacuo. Yield: 469.5 mg (88%).
Mp: >174 °C (dec). IR (KBr, cm-1): 2006 m, 1928 st ν(CO),
1722 sst ν(COOCH3). IR(CH2Cl2, cm-1): 2008 w, 1931 st
ν(CO). 31P{1H} NMR (CD2Cl2): δ ) 5.4 [s]. 31P CP/MAS
NMR: δ ) -0.4 [s]. 1H NMR (CD2Cl2): δ ) 2.42 [br m, 3 H,
CHHa], 3.27 [br m, 3 H, CHHe], 3.44 [s, 9 H, COOCH3], 7.10-
7.39 [m, 30 H, C6H5]. 13C CP/MAS NMR: δ ) 32.9 [s, CH2],
46.3 [s, CP], 50.6 [s, CH3], 126.6-139.3 [m, C6H5], 171.9 [s,
COOCH3], 197.9 [s, CO]. ΛM (CH2Cl2, 25 °C, cm2 Ω-1 mol-1):
0.6. MS (FAB), m/ z: 1038.1 [M+ - CO], 1031.2 [M+ - Cl-].
Anal. Calcd for C49H45ClIrO7P3 (1066.48): C, 55.19; H, 4.25;
Cl, 3.32. Found: C, 54.72; H, 4.19; Cl, 2.93.
Rea ction s of 1a -3a w ith HBF 4 a n d NH4P F 6. To a
solution of 1a -3a in 50 mL of CH2Cl2 was added 0.1 mL of an
aqueous solution of HBF4 (8 M) or 1 mL of an aqueous solution
of NH4PF6 (1 M). The reaction mixture was stirred for 15 h
at room temperature. The aqueous phase was removed, the
organic phase was concentrated in volume to 3 mL, and 50
mL of n-pentane was added. The resulting off-white precipi-
tate was filtered out, washed three times with 10 mL of
n-pentane each, and dried under reduced pressure.
Gen er a l Com m en ts. All reactions were performed under
a dry argon atmosphere using standard Schlenk techniques.
Solvents were distilled under Ar; benzene, toluene, diethyl
ether, and THF were distilled from Na/Ph2CO; n-pentane and
n-hexane were distilled from LiAlH4; dichloromethane was
distilled from CaH2; ethanol was distilled from Na; and
methanol was distilled from Mg. The gases H2, CO, and C2H4
were of commercial grade and used without further purifica-
tion. The phosphine ligands 1,10a 2,10b and 310c and the
complexes 1a ,10a and 3a ,10c and Ir(PPh3)2(CO)Cl30 were pre-
pared as described in the literature. 1H, 13C{1H}, and 31P{1H}
NMR spectra were recorded on a Bruker DRX 250 or a Bruker
AMX 400 operating at 250.13 or 400.13, 62.90 or 100.62, and
101.26 or 161.98 MHz, respectively. 1H chemical shifts were
referenced to the residual proton peaks of the solvents versus
TMS. 13C chemical shifts were calibrated against the deuter-
ated solvent multiplet relative to TMS. 31P chemical shifts
were measured relative to external 85% H3PO4 with downfield
values taken as positive. In addition to the 13C{1H} NMR
spectrum a 13C-DEPT31 experiment was routinely performed
for each compound. The assignments of the ethylene groups
1
in 1e-3e were supported by H/13C 2D HMQC32 experiments
using standard Bruker software. The numbers of hydrides
bound to the metal centers in 1b-3b, 1c-3c, 1f, and 2f were
also confirmed on the basis of the multiplicities of the off-
resonance proton-decoupled 31P NMR spectra. 1H, 13C, and
31P DNMR experiments were carried out on a Bruker AMX
400. The temperature was measured using the Eurotherm
temperature control unit and an external thermocouple (Pt
100). 13C and 31P CP/MAS NMR spectra were taken on a
Bruker ASX 300 (121 MHz). Infrared spectra were recorded
on a Bruker IFS 48. Mass spectra (FD) were detected on a
Finnigan MAT 711 A modified by AMD; FAB spectra were
detected on a Finnigan MAT TSQ70. Elemental analyses were
Car bon ylch lor oh ydr ido[cis,cis-1,3,5-tr is(diph en ylph os-
p h in o)cycloh exa n e]ir id iu m (III) Tetr a flu or obor a te (1b)
and Hexa flu or op h osp h a te (1b′). In both cases the amount
of 178.6 mg (0.20 mmol) of 1a was used. Yield: 187.0 mg (95%)
of 1b and 200.2 mg (96%) of 1b′. Mp: >185 °C (dec) (1b), >180
°C (dec) (1b′). - IR (KBr, cm-1): 2144 w ν(IrH), 2081 st ν(CO).
31P{1H} NMR (CDCl3): δ ) -143.0 [sept, 1J PF ) 713.3 Hz, PF6,
2
2
(30) Brauer, G. Handbook of Preparative Inorganic Chemistry; F.
Enke Verlag: Stuttgart, Germany, 1981; Vol. 3, p 2010.
(31) Benn, R.; Gu¨nther, H. Angew. Chem., Int. Ed. Engl. 1983, 22,
350.
(32) Bax, A.; Griffey, R. H.; Hawkins, B. L. J . Magn. Reson. 1983,
55, 301.
1b′], -34.9 [dd, J PP ) 23.3 Hz, J PP ) 10.0 Hz, P trans to H],
2 2 2
-27.9 [dd, J PP ) 23.3 Hz, J PP ) 23.3 Hz, P], -11.8 [dd, J PP
) 23.3 Hz, J PP ) 10.0 Hz, P]. 1H NMR (CDCl3): δ ) -8.37
2
2
2
2
4
[dddd, J PH ) 132.9 Hz, J PH ) 9.4 Hz, J PH ) 9.4 Hz, J HH
1.9 Hz, 1 H, IrH], 2.19-2.44 [m, 2 H, CHHa], 2.57-2.73 [m, 1
)
+
+

Functionalized Tripodal Phosphines
Organometallics, Vol. 15, No. 15, 1996 3401
2
H, CHHa], 2.88-3.33 [m, 3 H, CHHe], 3.39-3.57 [m, 3 H,
HCP], 6.83-7.72 [m, 30 H, C6H5]. 13C{1H} NMR (CDCl3): δ
ν(CO). 31P{1H} NMR (CDCl3): δ ) -23.8 [d, J PP ) 23.1 Hz,
2
1
P trans to H], -15.6 [t, J PP ) 23.1 Hz, P cis to H], H NMR
(CDCl3): δ ) -10.20 [m,33 2 H, IrH], 1.61-1.79 [m, 3 H,
CHHa], 1.90-2.37 [m, 3 H, CHHe], 2.67-2.85 [m, 3 H, HCP],
6.90-7.42 [m, 50 H, C6H5]. 13C{1H} NMR (CDCl3): δ ) 19.6,
1
) 21.5, 22.4, and 22.9 [d, J PC ) 33.4, 9.6, and 16.0 Hz, CP],
26.4, 26.7, and 27.8 [s, CH2], 125.6-134.1 [m, C6H5], 167.3
2
2
2
[ddd, J PC ) 114.8 Hz, J PC ) 6.1 Hz, J PC ) 6.1 Hz, CO]. ΛM
(CH2Cl2, 25 °C, cm2 Ω-1 mol-1): 27.1 (1b), 25.8 (1b′). MS
(FAB), m/ z: 893.5 [M+ - BF4-] (1b), 893.1 [M+ - PF6-] (1b′).
Anal. Calcd for C43H40BClF4IrOP3 (1b) (980.2): C, 52.69; H,
4.11; Cl, 3.62; F, 7.75. Found: C, 52.11; H, 3.99; Cl, 3.93; F,
8.13. Calcd for C43H40ClF6IrOP4 (1b′) (1038.3): C, 49.74; H,
3.88; Cl, 3.42; F, 10.98. Found: C, 49.22; H, 3.76; Cl, 3.64; F,
11.41.
1
21.0 [d, J PC ) 33.0, 31.5 Hz, CP], 25.8, 26.0 [s, CH2], 122.3-
136.8 [m, C6H5], 164.3 [q, 1J CB ) 49.3 Hz, ipso-B(C6H5)4-], 170.9
2
2
[dt, J PC ) 95.9 Hz, J PC ) 6.9 Hz, CO]. ΛM (CH2Cl2, 25 °C,
cm2 Ω-1 mol-1): 31.9 MS (FAB), m/ z: 859.2 [M+ - B(C6H5)4-].
Calcd for C67H61BIrOP3 (1178.2): C, 68.30; H, 5.22. Found:
C, 67.95; H, 5.52.
Ca r b on yld ih yd r id o[cis,cis-1,3,5-t r is(d ip h e n ylp h os-
p h in o)cycloh exa n e]ir id iu m (III) Ch lor id e (1c′). To a
degassed solution of 178.6 mg (0.20 mmol) of 1a in 50 mL of
CH2Cl2 was added H2, and the solution was stirred for 24 h.
After evaporation of the solvent, 2c′ was obtained quantita-
tively. The spectroscopic data are comparable to those of 1c.
Ca r b on yld ih yd r id o[cis,cis-1,3,5-t r is(d ip h e n ylp h os-
p h i n o )-1,3,5-t r i s (m e t h o x y c a r b o n y l)c y c lo h e x a n e ]-
ir id iu m (III) Tetr a p h en ylbor a te (2c). The amount of 213.4
mg (0.20 mmol) of 2a was used. Yield: 227.2 mg (84%). Mp:
>169 °C (dec). IR (KBr, cm-1): 2062 st ν(CO), 1727 st
ν(COOCH3). 31P{1H} NMR (CD2Cl2): δ ) -9.0 [d, 2J PP ) 23.9
Car bon ylch lor oh ydr ido[cis,cis-1,3,5-tr is(diph en ylph os-
p h i n o )-1,3,5-t r i s (m e t h o x y c a r b o n y l)c y c lo h e x a n e ]-
ir id iu m (III) Tetr a flu or obor a te (2b). The amount of 213.4
mg (0.20 mmol) of 2a was used. Yield: 205.5 mg (89%). Mp:
>157 °C (dec). IR (KBr, cm-1): 2137 w ν(IrH), 2091 st ν(CO),
1745 st, 1731 st, 1723 st ν(COOCH3). 31P{1H} NMR (CD2Cl2):
2
2
δ ) -18.2 [dd, J PP ) 23.3 Hz, J PP ) 10.9 Hz, P trans to H],
-11.4 [dd, 2J PP ) 23.3 Hz, 2J PP ) 23.3 Hz, P], -4.2 [dd, 2J PP
)
23.3 Hz, J PP ) 10.9 Hz, P]. 1H NMR (CD2Cl2): δ ) -9.08
2
2
2
2
[ddd, J PH ) 143.9 Hz, J PH ) 11.0 Hz, J PH ) 11.0 Hz, 1 H,
IrH], 2.69-3.44 [m, 6 H, CH2], 3.55, 3.59, 3.63 [s, 9 H,
COOCH3], 7.11-7.68 [m, 30 H, C6H5]. 13C{1H} NMR
Hz, P trans to H], -4.1 [t, J PP ) 23.9 Hz, P cis to H]. 1H
2
1
NMR (CD2Cl2): δ ) -10.25 [m,31 2 H, IrH], 2.36-2.86 [m, 3
H, CHHa], 3.11-3.51 [m, 3 H, CHHe], 3.53, 3.58 [s, 9 H,
COOCH3], 6.85-7.18 [m, 50 H, C6H5]. 13C{1H} NMR
(CD2Cl2): δ ) 33.7-33.8, 34.3-34.5 [m, CH2], 45.7-46.2 [m,
(CD2Cl2): δ ) 33.5-33.6 [m, CH2], 44.9, 45.7, 46.3 [d, J PC
)
14.5, 20.8, 22.6 Hz, CP], 53.5, 53.7, 53.7 [s, CH3], 124.4-136.8
2
2
2
[m, C6H5], 165.2 [ddd, J PC ) 119.5, J PC ) 5.4, J PC ) 5.4 Hz,
2
CO], 171.3, 171.7, 171.9 [d, J PC ) 5.8, 6.1, 6.4 Hz, COCH3].
ΛM (CH2Cl2, 25 °C, cm2 Ω-1 mol-1): 46.1. MS (FAB), m/ z:
1067.2 [M+ - BF4-]. Calcd for C49H46BClF4IrO7P3 (1154.30):
C, 50.99; H, 4.02; Cl, 3.07; F, 6.58. Found: C, 50.61; H, 4.22;
Cl, 2.98; F, 6.52.
1
CP], 53.4, 53.5 [s, CH3], 122.0-136.2 [m, C6H5], 164.4 [q, J CB
) 49.4 Hz, ipso-B(C6H5)4-], 169.0 [dt, J PC ) 101.3, J PC ) 6.7
Hz, CO], 172.0-172.1 [m, COOCH3]. ΛM (CH2Cl2, 25°C, cm2
Ω-1 mol-1): 39.8. MS (FD), m/ z: 1033.3 [M+ - B(C6H5)4-].
Calcd for C73H67BIrO7P3 (1352.28): C, 64.84; H, 4.99. Found:
C, 64.30; H, 5.17.
2
2
The reaction of 2a with NH4PF6 resulted in orthometalation
(see text).
Car bon ylch lor oh ydr ido[cis,cis-1,3,5-tr icyan o-1,3,5-tr is-
(d ip h en ylp h osp h in o)cycloh exa n e]ir id iu m (III) Tetr a flu -
or obor a te (3b). The amount of 193.5 mg (0.20 mmol) of 3a
was used. Yield: 196.3 mg (93%). Mp: >196 °C (dec). IR
(KBr, cm-1): 2230 w ν(CN), 2168 w ν(IrH), 2107 st ν(CO).
Ca r b on ylch lor od ih yd r id o[cis,cis-1,3,5-t r is(d ip h en yl-
p h osp h in o)-1,3,5-t r is(m et h oxyca r b on yl)cycloh exa n e]-
ir id iu m (III) (2c′). Hydrogen was passed through an orange
solution of 2a (1-3 mM) in dichloromethane until the color
turned to pale yellow (5-10 min). Evaporation of the solvent
in a fast stream of hydrogen gave 2c′ in quantitative yield. -
31P{1H} NMR (CD2Cl2): δ ) -23.0 [dd, 2J PP ) 21.6 Hz, 2J PP
)
2
2
IR (KBr, cm-1): 2105 m, 2049 w ν(IrH), 2007 m ν(CO), 1725
10.5 Hz, P trans to H], -14.4 [dd, J PP ) 24.3 Hz, J PP ) 21.6
Hz, P], -7.1 [dd, J PP ) 24.3 Hz, J PP ) 10.5 Hz, P]. 1H NMR
(CD2Cl2): δ ) -8.53 [ddd, 2J PH ) 145.60 Hz, 2J PH ) 10.74 Hz,
2J PH ) 10.74 Hz, 1 H, IrH], 3.08-4.30 [m, 6 H, CH2], 6.95-
7.98 [m, 30 H, C6H5]. 13C{1H} NMR (CD2Cl2): δ ) 30.0, 30.6,
31.4 [d, 1J PC ) 23.9, 17.61, 26.4 Hz, CP], 33.6 [br s, CH2], 33.9-
2
2
2
st ν(COOCH3). 31P{1H} NMR (CD2Cl2): δ ) 17.3 [d, J PP
)
2
9.8 Hz, P trans to H], 18.0 [s, P uncoord], 28.0 [d, J PP ) 9.8
2
Hz, P cis to H]. 1H NMR (CD2Cl2): δ ) -10.42 [ddd, J PH
)
2
2
155.4 Hz, J PH ) 19.0 Hz, J HH < 0.5 Hz, 1 H, IrH], -8.89
[ddd, 2J PH ) 17.0 Hz, 2J PH ) 17.0 Hz, 2J HH < 0.5 Hz, 1 H, IrH],
1.87-2.53 [m, 3 H, CHHa], 3.0-3.6 [m, 3 H, CHHe], 3.17, 3.44,
3.49 [s, 9 H, COOCH3], 7.1-7.9 [m, 30 H, C6H5]. 13C{1H} NMR
(CD2Cl2): δ ) 34.0-34.2, 37.3-38.3 [m, CH2], 43.2-47.5 [m,
CP], 51.7, 52.4, 52.6 [s, CH3], 127.1-138.9 [m, C6H5], 173.20-
173.84 [m, COOCH3], 186.08-186.22 [m, CO]. ΛM (CH2Cl2,
25 °C, cm2 Ω-1 mol-1): 0.6.
2
34.1, 34.7-34.9 [m, CH2], 118.3, 121.6, 123.9 [d, J PC ) 47.2,
2
56.6, 50.3, CN], 125.8-136.9 [m, C6H5], 163.7 [ddd, J PC
)
125.8, J PC ) 6.2, J PC ) 6.2 Hz, CO]. ΛM (CH2Cl2, 25°C, cm2
Ω-1 mol-1): 39.9. MS (FAB), m/ z: 968.5 [M+ - BF4-]. Calcd
for C46H37BClF4IrN3OP3 (1055.22): C, 52.36; H, 3.53; Cl, 3.36;
F, 7.20; N, 3.98. Found: C, 52.32; H, 3.84; Cl, 3.06; F, 6.93;
N, 3.92.
2
2
Ca r b on yld ih yd r id o[cis,cis-1,3,5-t r icya n o-1,3,5-t r is-
(d ip h en ylp h osp h in o)cycloh exa n e]ir id iu m (III) Tet r a -
p h en ylbor a te (3c). The amounts of 193.5 mg (0.20 mmol) of
3a and 75.3 mg (0.22 mmol) of NaBPh4 in 50 mL of THF were
used. Reaction time: 360 h. Since 3c reacts with dichloro-
methane, the workup was changed. The THF was removed
under reduced pressure, the remaining yellow solid was
extracted with 25 mL of ice cold CH2Cl2, and NaCl and residual
NaBPh4 were separated by filtration. The solution was
concentrated to 3 mL in volume at 0 °C, 50 mL of ice cold
n-pentane was added, and the resultant yellow precipitate was
filtered off, washed three times with 10 mL of n-pentane each,
and dried under reduced pressure. Yield: 215.6 mg (86%).
Mp: >148 °C (dec). IR (KBr, cm-1): 2231 w ν(CN), 2088 st
The treatment of 3a with NH4PF6 did not lead to any
reaction.
Gen er a l P r oced u r e for th e Rea ction s of 1a -3a w ith
H2, CO, a n d C2H4. A solution of 1a -3a in 50 mL of CH2Cl2
was degassed by using the freeze-pump-thaw technique. To
the frozen solution was added NaBPh4 and one of the gases
(1.3 bar) H2, CO, and C2H4, respectively. After the reaction
mixture had been allowed to warm to room temperature it was
stirred for 15 h. The reaction mixture was separated from
NaCl and residual NaBPh4, the solvent was concentrated in
volume to 3 mL, and 50 mL of n-pentane was added. The
resulting off-white precipitate was filtered out, washed three
times with 10 mL of n-pentane each, and dried under reduced
pressure.
Ca r b on yld ih yd r id o[cis,cis-1,3,5-t r is(d ip h e n ylp h os-
p h in o)cycloh exa n e]ir id iu m (III) Tetr a p h en ylbor a te (1c).
The amounts of 178.6 mg (0.20 mmol) of 1a and 75.3 mg (0.22
mmol) of NaBPh4 were used. Yield: 230.4 mg (98%). Mp:
>150 °C (dec). IR (KBr, cm-1): 2092 m-w ν(IrH), 2047 st
2
ν(CO). 31P{1H} NMR (CD2Cl2): δ ) -9.8 [d, J PP ) 9.1 Hz, P
2
trans to H], 7.8 [t, J PP ) 9.1 Hz, P cis to H]. 1H NMR
(CD2Cl2): δ ) -8.57 [m,31 2 H, IrH], 2.80-3.39 [m, 6 H, CH2],
6.77-7.78 [m, 50 H, C6H5]. 13C{1H} NMR (CDCl3): δ ) 30.5,
(33) AA′ part of an AA′MXX′ multiplet.
+
+

3402 Organometallics, Vol. 15, No. 15, 1996
Sto¨ssel et al.
1
2
30.7 [d, J PC ) 5.7, 5.7 Hz, CP], 35.8 [br. s, CH2], 36.7 [t, J PC
) 7.6 Hz, CH2], 120.1-121.1 [m, CN], 122.2-136.5 [m, C6H5],
128.8-134.4 [m, C6H5], 171.7 [br m, COOCH3]. ΛM (CH2Cl2,
25 °C, cm2 Ω-1 mol-1): 40.8.
164.4 [q, J CB ) 49.4 Hz, ipso- B(C6H5)4-] ΛM (CH2Cl2, 25 °C,
1
Dica r b on yl[cis,cis-1,3,5-t r icya n o-1,3,5-t r is(d ip h e n -
ylp h osp h in o)cycloh exa n e]ir id iu m (I) Tetr a p h en ylbor a te
(3d ). As starting materials, the amounts of 193.5 mg (0.20
mmol) of 3a and 75.3 mg (0.22 mmol) of NaBPh4 were used.
Reaction time: 100 h. Yield: 237.9 mg (93%). Mp: >187 °C
(dec). IR (KBr, cm-1): 2233 w ν(CN), 2064 st, 1998 st ν(CO).
31P{1H} NMR (CD2Cl2): δ ) -10.3 [s]. 1H NMR (CD2Cl2): δ
) 3.09-3.45 [m, 6 H, CH2], 6.87-7.58 [m, 50 H, C6H5].
13C{1H} NMR (CD2Cl2): δ ) 30.5-30.9 [m, CP], 36.3 [br s,
cm2 Ω-1 mol-1): 37.4. MS (FD), m/ z: 933.4 [M+ - B(C6H5)4-].
Calcd for C70H58BIrON3P3 (1253.20): C, 67.09; H, 4.66; N, 3.35.
Found: C, 66.76; H, 4.82; N, 3.27.
Ca r b on yld ih yd r id o[cis,cis-1,3,5-t r icya n o-1,3,5-t r is-
(d ip h en ylp h osp h in o)cycloh exa n e]ir id iu m (III) Ch lor id e
(3c′). IR (CH2Cl2, cm-1): 2083 st ν(CO). 31P{1H} NMR
(CD2Cl2): δ ) -9.8 [d, 2J PP ) 9.1 Hz, P trans to H], 7.7 [t, 2J PP
) 9.1 Hz, P cis to H].
1
CH2], 118.3 [br m, CN], 122.1-136.3 [m, C6H5], 164.5 [q, J CB
Dica r bon yl[cis,cis-1,3,5-tr is(d ip h en ylp h osp h in o)cyclo-
h exa n e]ir id iu m (I) Tetr a p h en ylbor a te (1d ). As starting
materials, the amounts of 178.6 mg (0.20 mmol) of 1a and 75.3
mg (0.22 mmol) of NaBPh4 were used. Yield: 228.2 mg (95%).
Mp: >145 °C (dec). IR (KBr, cm-1): 2039 st, 1961 st ν(CO).
31P{1H} NMR (CDCl3): δ ) -21.8 [s]. 1H NMR (CDCl3): δ )
1.79-1.97 [m, 3 H, CHHa], 2.07-2.38 [m, 3 H, CHHe], 2.69-
2.82 [m, 3 H, HCP], 6.90-7.42 [m, 50 H, C6H5]. 13C{1H} NMR
(CDCl3): δ ) 21.3 [d, 1J PC ) 32.5 Hz, CP], 26.6 [s, CH2], 121.8-
136.3 [m, C6H5], 164.4 [q, 1J CB ) 49.2 Hz, ipso-B(C6H5)4-], 180.8
) 49.3 Hz, ipso-B(C6H5)4-], 175.6 [q, J PC ) 23.1 Hz, CO]. ΛM
2
(CH2Cl2, 25 °C, cm2 Ω-1 mol-1): 40.1. MS (FD), m/ z: 960.4
-
[M+ - B(C6H5)4-], 931.6 [M+ - B(C6H5)4 - CO]. Calcd for
C
71H56BIrN3O2P3 (1279.19): C, 66.67; H, 4.41; N, 3.28.
Found: C, 66.12; H, 4.47; N, 3.32.
Dica r b on yl[cis,cis-1,3,5-t r icya n o-1,3,5-t r is(d ip h e n -
ylp h osp h in o)cycloh exa n e]ir id iu m (I) Ch lor id e (3d ′). IR
(CH2Cl2, cm-1): 2066 st, 1998 st ν(CO). 31P{1H} NMR
(CD2Cl2): δ ) -10.4 [s].
Car bon yl(eth en e)[cis,cis-1,3,5-tr is(diph en ylph osph in o)-
cycloh exa n e]ir id iu m (I) Tetr a p h en ylbor a te (1e). A 178.6
mg (0.20 mmol) amount of 1a and 75.3 mg (0.22 mmol) of
NaBPh4 were used as starting materials. Yield: 207.8 mg
(86%). Mp: >150 °C (dec). IR (KBr, cm-1): 2025 st-m, ν(CO).
31P{1H} NMR (CDCl3, 21 °C): δ ) -27.1 [br s]. 1H NMR
(CDCl3, 21°C): δ ) 2.02, 2.80 [AA′XX′, 4 H, C2H4], 2.07-2.38
[m, 6 H, CHaHe], 2.74-2.87 [m, 3 H, HCP], 6.84-7.44 [m, 50
C6H5]. 13C{1H} NMR (CDCl3, 21°C): δ ) 20.1 [s, C2H4], 22.9
[q, J PC ) 22.1 Hz, CO]. ΛM (CH2Cl2, 25 °C, cm2 Ω-1 mol-1):
2
31.2. MS (FAB), m/ z: 885.2 [M+ - B(C6H5)4-]. Calcd for
C
68H59BIrO2P3 (1204.2): C, 67.83; H, 4.94. Found: C, 67.38;
H, 5.10.
Dica r bon yl[cis,cis-1,3,5-tr is(d ip h en ylp h osp h in o)cyclo-
h exa n e]ir id iu m (I) Ch lor id e (1d ′). After a solution of 1a
(178.6 mg, 0.20 mmol) in 50 mL of CH2Cl2 had been degassed
by using the freeze-pump-thaw technique, CO (1.3 bar) was
added. The reaction mixture was allowed to warm to room
temperature and was stirred for 15 h. The solution was
concentrated to 3 mL in volume, and 50 mL of n-pentane was
added. The resulting off-white precipitate was filtered out,
washed three times with 10 mL of n-pentane each, and dried
under reduced pressure. Yield: 183.5 mg (99%). Mp: >180
°C (dec). IR (KBr, cm-1): 2047 st, 1944 st ν(CO). 31P{1H}
NMR (CDCl3): δ ) -21.9 [s]. 1H NMR (CDCl3): δ ) 2.15-
2.35 [m, 3 H, CHHa], 3.20-3.65 [m, 6 H, CHHe, HCP], 6.95-
7.34 [m, 30 H, C6H5]. 13C{1H} NMR (CDCl3): δ ) 21.8 [d, 1J PC
) 32.3 Hz, CP], 26.7 [s, CH2], 128.7-131.8 [m, C6H5], 173.0
1
[d, J PC ) 33.7 Hz, CP], 27.6 [s, CH2], 121.8-136.3 [m, C6H5],
164.5 [q, 1J CB ) 49.3 Hz, ipso-B(C6H5)4-], 181.1 [q, 2J PC ) 22.0
Hz, CO]. ΛM (CH2Cl2, 25 °C, cm2 Ω-1 mol-1): 35.9. MS (FAB),
m/ z: 885.2 [M+ - B(C6H5)4-]. Calcd for C69H63BIrOP3
(1204.2): C, 68.82; H, 5.27. Found: C, 68.30; H, 5.20.
Car bon yl(eth en e)[cis,cis-1,3,5-tr is(diph en ylph osph in o)-
1,3,5-tr is(m eth oxyca r bon yl)cycloh exa n e]ir id iu m (I) Tet-
r a p h en ylbor a te (2e). The amounts of 213.4 mg (0.20 mmol)
of 2a and 75.3 mg (0.22 mmol) of NaBPh4 were applied.
Yield: 228.8 mg (83%). Mp: >183 °C (dec). IR (KBr, cm-1):
2043 st ν(CO), 1726 st ν(COOCH3). 31P{1H} NMR (CH2Cl2,
21 °C): δ ) -13.8 [br s]. 1H NMR (CD2Cl2, 21 °C): δ ) 2.10,
2.53 [AA′XX′, N ) 7.9 Hz, 4 H, C2H4], 2.57 [ABX2, 2J HH ) 17.2,
[q, J PC ) 32.3 Hz, CO]. ΛM (CH2Cl2, 25 °C, cm2 Ω-1 mol-1):
2
29.1. MS (FAB), m/ z: 884.9 [M+ - Cl-]. Calcd for C44H39
-
ClIrO2P3 (920.4): C, 57.42; H, 4.27; Cl, 3.85. Found: C, 56.98;
H, 4.39; Cl, 3.54.
2
3
3J PH ) 32.9 Hz, 3 H, CHaHe], 3.27 [ABX2, J HH ) 17.2, J PH
)
9.2 Hz, 3 H, CHaHe], 3.46 [s, 9 H, COOCH3], 6.85-7.76 [m, 50
H, C6H5]. 13C{1H} NMR (CD2Cl2, 21 °C): δ ) 24.5 [s, C2H4],
34.4 [s, CH2], 46.3 [d, 1J PC ) 14.3 Hz, CP], 53.0 [s, CH3], 121.5-
136.2 [m, C6H5], 164.2 [q, 1J CB ) 48.6 Hz, ipso-B(C6H5)4-], 171.5
[s, COOCH3]. ΛM (CH2Cl2, 25 °C, cm2 Ω-1 mol-1): 44.3. MS
Dica r bon yl[cis,cis-1,3,5-tr is(d ip h en ylp h osp h in o)-1,3,5-
t r is(m et h oxyca r b on yl)cycloh exa n e]ir id iu m (I) Tet r a -
p h en ylbor a te (2d ). The amount of 213.4 mg (0.20 mmol) of
2a was used as starting material. Yield: 245.3 mg (89%).
Mp: >177 °C (dec). IR (KBr, cm-1): 2049 st, 1982 st ν(CO),
1727 st ν(COOCH3). 31P{1H} NMR (CD2Cl2): δ ) -5.3 [s]. 1H
NMR (CD2Cl2): δ ) 2.58-2.92 [m, 3 H, CHHa], 3.32-3.48 [m,
3 H, CHHe], 3.51 [s, 9 H, COOCH3], 6.84-7.44 [m, 50 H, C6H5].
13C{1H} NMR (CD2Cl2): δ ) 35.1 [br m, CH2], 45.9-46.8 [m,
CP], 53.6 [s, CH3], 122.0-136.3 [m, C6H5], 164.4 [q, 1J CB ) 49.4
(FAB), m/ z: 1067.2 [M+ - B(C6H5)4-]. Calcd for C75H69
-
BIrO7P3 (1378.32): C, 65.36; H, 5.05. Found: C, 65.16; H,
5.32.
Ca r b on yl(et h en e)[cis,cis-1,3,5-t r icya n o-1,3,5-t r is(d i-
p h en ylp h osp h in o)cycloh exa n e]ir id iu m (I) Tetr a p h en yl-
bor a te (3e). Application of 193.5 mg (0.20 mmol) of 3a and
75.3 mg (0.22 mmol) of NaBPh4 with a reaction time of 240 h
gave a 220.0 mg (86%) yield. Mp: >183 °C (dec). IR (KBr,
cm-1): 2233 w ν(CN), 2055 st ν(CO). 31P{1H} NMR (CH2Cl2,
21 °C): δ ) -19.1 [br s]. 1H NMR (CD2Cl2, 21 °C): δ ) 2.40,
2.91 [AA′XX′, N ) 7.6 Hz, 4 H, C2H4], 3.15 [ABX2, 2J HH ) 15.9,
Hz, ipso-B(C6H5)4-], 171.7 [s, COOCH3], 178.2 [q, J PC ) 23.6
2
Hz, CO]. ΛM (CH2Cl2, 25 °C, cm2 Ω-1 mol-1): 43.9. MS (FD),
m/ z: 1059.1 [M+ - B(C6H5)4-], 1031.2 [M+ - B(C6H5)4- - CO].
Calcd for C74H65BIrO8P3 (1378.27): C, 64.49; H, 4.75. Found:
C. 63.92; H, 5.10.
2
3
Dica r bon yl[cis,cis-1,3,5-tr is(d ip h en ylp h osp h in o)-1,3,5-
tr is(m eth oxyca r bon yl)cycloh exa n e]ir id iu m (I) Ch lor id e
(2d ′). Carbon monoxide was passed through an orange
solution of 2a (1-3 mM) in dichloromethane until the color
turned to pale yellow. Evaporation of the solvent in a fast
stream of carbon monoxide gave 2d ′ in quantitative yield. IR
(KBr, cm-1): 2043 st, 1971 st ν(CO), 1727 st ν(COOCH3). IR
(CH2Cl2, cm-1): 1991 st, 1973 m ν(CO), 1728 st ν(COOCH3).
31P{1H} NMR (CD2Cl2): δ ) -5.3 [s]. 1H NMR (CD2Cl2): δ )
2.72-3.04 [m, 3 H, CHHa], 3.24-3.47 [m, 3 H,CHHe], 3.54 [s,
9 H, COOCH3], 7.17-7.41 [m, 30 H, C6H5]. 13C{1H} NMR
(CD2Cl2): δ ) 35.0 [s, CH2], 46.1 [br m, CP], 53.6 [s, CH3],
3J PH ) 26.3 Hz, 3 H, CHaHe], 3.30 [ABX2, J HH ) 15.9, J PH
)
7.6 Hz, 3 H, CHaHe], 6.85-7.34 (m, 50 H, C6H5). 13C{1H} NMR
1
(CD2Cl2, 21°C): δ ) 27.1 [s, C2H4], 31.1 [d, J PC ) 18.1 Hz,
CP], 35.8 [s, CH2], 118.4 [s, CN], 121.0-136.0 [m, C6H5], 164.1
[q, J CB ) 50.0 Hz, ipso-B(C6H5)4-]. ΛM (CH2Cl2, 25 °C, cm2
1
Ω-1 mol-1): 40.3. MS (FAB), m/ z: 960.0 [M+ - B(C6H5)4-].
Calcd for C72H60BIrN3OP3 (1279.24): C, 67.60; H, 4.73; N, 3.29.
Found: C, 66.69; H, 4.99; N, 2.92.
Car bon ylh ydr ido[cis,cis-1,3,5-tr is(diph en ylph osph in o)-
cycloh exa n e]ir id iu m (III) Tetr a p h en ylbor a te (1f). To a
suspension of 1a (178.6 mg, 0.20 mmol) in 50 mL of benzene
was added NaBPh4 (75.3 mg, 0.22 mmol). After stirring of
+
+

Functionalized Tripodal Phosphines
Organometallics, Vol. 15, No. 15, 1996 3403
Ta ble 3. Exp er im en ta l Da ta for th e X-r a y
Diffr a ction Stu d ies of th e Com p lexes 3d a n d 2f
the reaction mixture at 85°C for 15 h, it was allowed to cool
down to room temperature. After the solution had been
separated from NaCl and residual NaBPh4, the volume of the
solution was reduced to 3 mL and 50 mL of n-pentane was
added. The resulting off-white precipitate was filtered out,
washed three times with 10 mL of n-pentane each, and dried
under reduced pressure. Yield: 185 mg (79%). Mp: >155 °C
(dec). IR (KBr, cm-1): 2077 w ν(IrH), 2025 m ν(CO). 31P{1H}
3d
2f
formula
fw
cryst syst
space group
a, Å
C83H80BIrN3O5P3
1495.42
orthorhombic
P212121
16.577(3)
19.972(4)
C73H65BIrO7P3
1350.17
monoclinic
P21/c
9.103(3)
26.834(6)
24.852(5)
91.36(2)
6069(3)
4
2
2
NMR (CD2Cl2): δ ) -90.6 [dd, J PP ) 27.8, Hz J PP ) 16.3
b, Å
c, Å
2
2
Hz, P ortho-C), -30.5 [dd, J PP ) 16.3 Hz, J PP ) 16.3 Hz, P
21.355(4)
2
2
1
â, deg
V, Å3
Z
trans to H], -26.6 [dd, J PP ) 27.8 Hz, J PP ) 16.3 Hz, P]. H
NMR (CDCl3): δ ) -7.81 [dddd, 2J PH ) 119.8 Hz, 2J PH ) 11.0
7070(2)
4
1.405
3064
2
4
Hz, J PH ) 11.0 Hz, J HH ) 2.6 Hz, 1 H, IrH], 1.84-3.35 [m, 9
H, C6H9], 9.95-7.95 [m, 49 H, C6H5]. 13C{1H} NMR (CDCl3):
d
calcd, g cm-3
1.478
2744
F(000)
1
δ ) 16.0, 21.7, 23.2 [d, J PC ) 27.0, 27.9, 31.6 Hz, CH], 26.0,
cryst size, mm
µ(Mo KR) mm-1
diffractometer
2θ range, deg
temp, K
0.40 × 0.30 × 0.20 0.20 × 0.10 × 0.10
1
26.7, 27.2 [s, CH2], 122.0-137.0 [m, C6H5], 164.5 (q, J CB
)
2.012
2.336
Siemens P4
4-50
50.0 Hz, ipso-B(C6H5)4-]. ΛM (CH2Cl2, 25 °C, cm2 Ω-1 mol-1):
25.6. MS (FAB), m/ z: 857.6 [M+ - B(C6H5)4-]. Calcd for
4-50
C
67H59BIrOP3 (1176.2): C, 68.42; H, 5.06. Found: C, 67.85;
H, 5.49.
Car bon ylh ydr ido[cis,cis-1,3,5-tr is(diph en ylph osph in o)-
173(2)
26488
10419
173(2)
18645
5672
no. of data collcd
no. of unique data
with I g 2σ(I)
1,3,5-tr is(m eth oxycar bon yl)cycloh exan e]ir idiu m (III) Tet-
r a p h en ylbor a t e (2f). To a solution of 2a (213.4 mg, 0.20
mmol) in 100 mL of dichloromethane was added NaBPh4 (75.3
mg, 0.22 mmol). After being stirred at room temperature for
15 h, the reaction mixture was separated from NaCl and
residual NaBPh4. The solution was concentrated in volume
to 3 mL, 50 mL of n-pentane was added, and the resultant
off-white precipitation was filtered out, washed three times
with 10 mL of n-pentane each, and dried under reduced
pressure. Yield: 224.1 mg (83%). Mp: >180 °C (dec). IR
(KBr, cm-1): 2085 w ν(IrH), 2048 st ν(CO), 1728 st ν(COOCH3).
no. of params refined 866
767
S
1.885
0.052
0.115
1.085
0.032
0.066
R1a
wR2b
R1 ) ∑||Fo| - |Fc||/∑|Fo|. b wR2 ) [∑[w(Fo2 - Fc2)2]/[∑[w(Fo2)2]]0.5
.
a
collected with the ω-scan technique with scan speed varying
from 5 to 20° min-1 and 8 to 30° min-1 in ω, respectively. Scan
ranges for 3d and 2f were 0.7 and 1.2, respectively. For both
structures empirical absorption corrections were performed (ψ-
scan, maximal and minimal transmissions 0.477 and 0.408
(3d ) and 0.657 and 0.488 (2f)). All structures were solved by
Patterson methods34 and refined by least squares with aniso-
tropic thermal parameters for all non-hydrogen atoms. Hy-
drogen atoms were included in calculated positions (riding
model). Maximum and minimum peaks in the final difference
synthesis were 1.012 and -0.686 eÅ-3 (3d ) and 1.393 and
-0.650 eÅ-3 (2f), respectively. The asymmetric unit of com-
pound 3d contains three molecules of THF. Final atomic
coordinates are collected in the Supporting Information.
IR (CHCl3, cm-1): 2086 w ν(IrH), 2056 st ν(CO), 1731 st
2
ν(COOCH3). 31P{1H} NMR (CD2Cl2): δ ) -81.7 [dd, J PP
)
)
2
2
2
22.7 Hz, J PP ) 18.1 Hz, P], -9.4 [dd, J PP ) 18.1 Hz, J PP
2
2
18.1 Hz, P trans to H], -6.2 [dd, J PP ) 22.7 Hz, J PP ) 18.1
Hz, P]. 1H NMR (CD2Cl2): δ ) -8.48 [ddd, J PH ) 130.0 Hz,
2
2
2J PH ) 14.2 Hz, J PH ) 10.4 Hz, 1 H, IrH], 2.58-3.10 [m, 5 H,
CH2], 3.49, 3.57, 3.82 [s, 9 H, COOCH3], 3.84-3.96 [m, 1 H,
CH2], 6.60-7.73 [m, 49 H, C6H5]. 13C{1H} NMR (CD2Cl2): δ
1
) 33.5-35.8 [m, CH2], 40.3, 45.1, 48.9 [d, J PC ) 23.1, 12.1,
17.9 Hz, CP], 53.2, 53.3, 54.9 [s, CH3], 122.0-136.7 [m, C6H5],
148.6 [ddd, 2J PC ) 61.0 Hz, 2J PC ) 5.6 Hz, 2J PC ) 5.6 Hz, IrC],
164.3 [q, 1J CB ) 49.3 Hz, ipso-B(C6H5)4-], 170.3 [m, CO], 170.0,
170.7, 170.8 [d, 2J PC ) 6.5, 5.5, 5.7 Hz, COOCH3]. ΛM (CH2Cl2,
Ack n ow led gm en t. We thank the DEGUSSA AG for
a loan of IrCl3‚xH2O and the Fonds der Chemischen
Industrie, Frankfurt/Main, Germany, and the Univer-
sity of Tu¨bingen for financial support. Prof. W. C.
Kaska, University of California, Santa Barbara, CA, and
Prof. E. Lindner, University of Tu¨bingen, for helpful
discussions and support are also greatly acknowledged.
25°C, cm2 Ω-1 mol-1): 43.7. MS (FD), m/ z: 1031.9 [M+
-
B(C6H5)4-]. Calcd for C73H65BIrO7P3 (1350.26): C, 64.94; H,
4.85. Found: C, 64.35; H, 5.18.
X-r a y Diffr a ction Stu d y. Single crystals of 3d and 2f
were grown from THF by slow evaporation of the solvent (3d )
and by diffusion of ether into a THF solution of 2f. Both
crystals were mounted on a glass fiber and transferred to a
P4 Siemens diffractometer. Rotation photographs were taken,
and a photosearch was performed to find a suitable reduced
cell (graphite-monochromated Mo KR radiation). The lattice
constants were determined with 25 precisely centered high-
angle reflections and refined by least-square methods. The
final cell parameters and specific data collection parameters
for 3d and 2f are collected in Table 3. Intensities were
Su p p or tin g In for m a tion Ava ila ble: Tables of atomic
coordinates, thermal parameters, bond distances and angles,
and data collection parameters (23 pages). Ordering informa-
tion is given on any current masthead page.
OM960006Q
(34) Sheldrick, G. M. SHELXTL 5.03 program; University of Go¨t-
tingen, Germany, 1995.
+
+