Unsaturated rh(i) and rh(iii) naphthyl-based pcp complexes. major steric effect on reactivity

Article abstract of DOI:10.1021/om801147w

The addition of an equimolar amount of hydrochloric acid (-4.0 M in dioxane) to THF solutions of the binuclear Rh(I) complex [(C₁₀H ₅(CH₂Pr₂)₂)Rh(η¹- N₂)]₂ (1a) at roo

Full text of DOI:10.1021/om801147w

1900
Organometallics 2009, 28, 1900–1908
Unsaturated Rh(I) and Rh(III) Naphthyl-Based PCP Complexes.
Major Steric Effect on Reactivity
Christian M. Frech,*,† Linda J. W. Shimon,‡ and David Milstein§
Department of Inorganic Chemistry, UniVersity of Zurich, 8057 Zurich, Switzerland and Departments of
Organic Chemistry and Chemical SerVices, The Weizmann Institute of Science, RehoVot 76100, Israel
ReceiVed December 2, 2008
The addition of an equimolar amount of hydrochloric acid (∼4.0 M in dioxane) to THF solutions of
the binuclear Rh(I) complex [(C10H5(CH2PiPr2)2)Rh(η1-N2)]2 (1a) at room temperature led to an inseparable
mixture of 1a, [(C10H5(CH2PiPr2)2)Rh(Cl)(H)] (2a), and [(C10H5(CH2PiPr2)2)Rh(Cl)2 (dioxane)]2 (3a).
Exclusive formation of 2a was achieved by slow addition of an equimolar amount of hydrochloric acid
(∼0.4 M in dioxane) to a THF solution of 1a at -35 °C, whereas exclusive formation of 3a was obtained
when a second equivalent or an excess (∼10 equiv) of hydrochloric acid (∼4.0 M in dioxane) was added
to THF solutions of 2a (or to reaction mixtures, which consist of 1a, 2a, and 3a). 3a was structurally
characterized. In striking difference to the reactivity pattern of 1a, treatment of THF solutions of the
bulky tBu derivative 1b with an equimolar amount or even a large excess (∼25 equiv) of hydrochloric
acid (∼4.0 M in dioxane) exclusively yielded the hydrido chloro complex [(C10H5(CH2PtBu2)2)Rh(Cl)(H)]
(2b). Chloride abstraction from 2a and 2b with AgBF4 exclusively yielded the hydrido rhodium(III)
complexes [(C10H5(CH2PR2)2)Rh(H)(F-BF3)] (9a and 9b) with coordination of the counteranion. On
the other hand, when an equimolar amount of AgBArF was added to methylene chloride (or diethyl
4
ether) solutions of 2a and 2b the cationic, the solvent-stabilized rhodium hydride complexes of type
[(C10H5(CH2PR2)2)Rh(solv)(H)][BArF ] (10a and 10b) were formed. If the electron density of the metal
4
centers of 9 (and 10) is reduced further by substitution of the coordinated anion of 9 (or the solvent
molecule of 10) with a carbonyl ligand, instant migration of the hydride ligand to the aromatic unit to
yield the stable carbonyl complexes of type [(C10H5(CH2PR2)2(H)Rh(CO)][X] (X ) BArF 11a,11b; X
4
) BF4 11a′,11b′) with η2 Caryl-H agostic interactions was observed. Treatment of 2b with CO gas yielded
both isomeric forms of [(C10H5(CH2PtBu2)2)Rh(H)(Cl)(CO)] 14b (CO trans to the hydride ligand) and
14b′ (CO trans to the aromatic pincer core). In contrast, when an excess of CO gas was added to THF
(or methylene chloride), solutions of 2a, 14a′ was exclusively formed within 20 min at room temperature.
d8 14e- complexes, which have frequently been postulated as
Introduction
intermediates in carbon-carbon5 and carbon-hydrogen6,7 bond
Catalytic processes are initiated by the coordination and
activation of substrate molecules by coordinatively unsaturated
metal centers,1 which are stabilized in solution by coordination
of solvent molecules,2 counteranions,3 or agostic interactions
with ligands.4 The degree of stabilization and hence the
reactivity of a transition-metal complex toward substrate
molecules depend on the electronic properties and steric bulk
of the coordinated ligands, the counteranion, and the solvent.
Consequently, these properties can be of high importance in
catalysis. Therefore, efforts to prepare and investigate d6 and
activation and functionalization, considerably increased. Thus,
formally 14e- d6 iridium,4a rhodium,8 ruthenium,2,4b and d8
rhodium4c,9 complexes as well as examples of unsaturated
platinum d6 complexes were described.10
We report here different reactivity modes of seemingly very
similar rhodium pincer complexes that are controlled by steric
effects. In addition, we describe the facile synthesis of highly
unsaturated formally 14e- rhodium d6 complexes, which are,
(5) For recent reviews, see: (a) Rybtchinski, B.; Milstein, D. Angew.
Chem., Int. Ed. 1999, 38, 870. (b) Murakami, M.; Ito, Y. In ActiVation of
UnreactiVe Bonds and Organic Synthesis; Murai, S., Ed.; Topics in
Organometallic Chemistry; Springer: Heidelberg, 1999; Vol. 3, p 97. See
also: (c) Gandelman, M.; Vigalok, A.; Konstantinovski, L.; Milstein, D.
J. Am. Chem. Soc. 2000, 122, 9848. (d) Rybtchinski, B.; Oevers, S.; Montag,
M.; Vigalok, A.; Rosenberg, H.; Martin, J. M. L.; Milstein, D. J. Am. Chem.
Soc. 2001, 123, 9064.
(6) (a) Shilov, A. E. In The ActiVation of Saturated Hydrocarbons by
Transition Metal Complexes; Reidel: Dordrecht, The Netherlands, 1984.
(b) Crabtree, R. H. In The Chemistry of Alkanes and Cycloalkanes; Patai,
S., Rappoport, Z., Eds.; Wiley: New York, 1992; p 653. (c) Shilov, A. E.;
Shulpin, G. B. Chem. ReV. 1997, 97, 2879.
* To whom correspondence should be addressed. E-mail: chfrech@
aci.uzh.ch.
† University of Zurich.
‡ Department of Chemical Services, The Weizmann Institute of Science.
§ Department of Organic Chemistry, The Weizmann Institute of Science.
(1) 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.
(2) Huang, D.; Huffman, J. C.; Bollinger, J. C.; Eisenstein, O.; Caulton,
K. G. J. Am. Chem. Soc. 1997, 119, 7398.
(3) (a) Beck, W.; Su¨nkel, K. Chem. ReV. 1988, 88, 1405. (b) Strauss,
S. H. Chem. ReV. 1993, 93, 927.
(4) (a) Cooper, A. C.; Clot, E.; Huffman, J. C.; Streib, W. E.; Maseras,
F.; Eisenstein, O.; Caulton, K. G. J. Am. Chem. Soc. 1999, 121, 97. and
references therein. (b) Baratta, W.; Herdtweck, E.; Rigo, P. Angew. Chem.,
Int. Ed. 1999, 38, 1629. (c) Urtel, H.; Meier, C.; Eisentra¨ger, F.; Rominger,
F.; Joschek, J. P.; Hofmann, P. Angew. Chem., Int. Ed. 2001, 40, 781.
(7) (a) Gupta, M.; Hagen, C.; Flesher, R. J.; Kaska, W. C.; Jensen, C. M.
Chem. Commun. 1996, 2083. (b) Xu, W.; Rosini, G. P.; Gupta, M.; Jensen,
C. M.; Kaska, W. C.; Krogh-Jespersen, K.; Goldman, A. S. Chem. Commun.
1997, 2273. (c) Liu, F.; Pak, E. B.; Singh, B.; Jensen, C. M.; Goldman,
A. S. J. Am. Chem. Soc. 1999, 121, 4086.
10.1021/om801147w CCC: $40.75
2009 American Chemical Society
Publication on Web 02/19/2009

Unsaturated Rh(I) and Rh(III) PCP Complexes
Organometallics, Vol. 28, No. 6, 2009 1901
Scheme 1. Reaction of 1a with Hydrochloric Acid and Subsequent Reactions
depending on the steric bulk of the counteranion, stabilized either
by coordination of a solvent molecule or by the counteranion.
the metal center would lead to a trans-dihydride complex in a
square pyramidal arrangement.12 Indeed, no intermediates were
detected by 31P{1H} NMR spectroscopy when an equimolar
amount of hydrochloric acid (∼4.0 M in dioxane) was added
to THF solutions of 2a even at -35 °C. When 2 equiv or an
excess (∼5 equiv) of the hydride reagent LiHBEt3 (∼1.0 M in
THF) was added to THF (or benzene) solutions of 3a, 1a was
quantitatively formed. Treatment of cold (-35 °C) THF
solutions of 3a with an equimolar amount of LiHBEt3 exclu-
sively yielded the rhodium hydride complex 2a. The 31P{1H}
NMR spectrum of 3a exhibits two resonance signals with dd
(AB) pattern centered at δ ) 50.75 and 49.82 ppm with coupling
Results and Discussion
The addition of an equimolar amount (relative to the metal)
of hydrochloric acid (∼4.0 M in dioxane) to THF solutions of
11
the binuclear Rh(I) complex [(C10H5(CH2PiPr2)2)Rh(η1-N2)]2
(1a) at room temperature led to an inseparable mixture of 1a,
[(C10H5(CH2PiPr2)2)Rh(Cl)(H)] (2a), and [(C10H5(CH2PiPr2)2)-
Rh(Cl)2(dioxane)]2 (3a) (Scheme 1).
The 31P{1H} NMR spectrum of this reaction mixture dis-
played three different signals centered at δ ) 50.23, 64.23, and
66.34 ppm, of which the latter belongs to 1a. The signal at δ )
64.23 ppm, attributed to the rhodium hydride complex 2a, has
a dd (AB) pattern with its center at δ ) 64.46 and 64.00 ppm
with coupling constants of 2JPP ) 396.2 and 1JRhP ) 117.5 Hz.
2a was formed in approximately 70% yield, while both 1a and
2
1
constants of JPP ) 360.7 and JRhP ) 96.2 Hz, indicating a
RhIII center. In addition to all the signals attributed to the pincer
1
ligand in the H and 13C{1H} NMR spectra, resonance signals
at δ ) 3.72 and 67.7 ppm, respectively, were detected, indicating
a coordinated dioxane molecule in 3a. Dioxane coordination
was confirmed by X-ray diffraction crystallographic analysis
of single crystals of 3a. Suitable crystals of complex 3a were
grown from a concentrated benzene solution at room temper-
ature. The crystal structure of 3a revealed a dinuclear rhodium
dichloro complex, bridged by a dioxane molecule. 3a is the first
crystallographically characterized rhodium-dioxane complex
reported (Figure 1). The rhodium centers have slightly distorted
octahedral geometries with axially arranged chloride ligands.
The dioxane molecule is trans coordinated to the Cipso carbon
atom and twisted around the C-Rh-dioxane-Rh-C axis. The
dihedral angles of C12-Rh1-O1-C25 and C12-Rh1-O1-C26
are 122.0(1) and -75.9(1)°, respectively. The Rh1-O1 and
Rh1A-O1A bond distances measure 2.371(3) Å and are some
of the longest reported when compared with the few structurally
characterized rhodium complexes containing Rh-OTHF interac-
tions, whose Rh-OTHF bond lengths vary in the range of
2.077-2.450 Å.13,14
1
3a were obtained in a yield of ∼15% (by integration). The H
NMR spectrum of this mixture displayed, in addition to all the
resonances due to the pincer ligands, a sharp and characteristic
hydride signal at δ ) -24.53 ppm with dt pattern and coupling
1
2
constants of JRhH ) 44.6 and JPH ) 7.8 Hz, which confirms
the formation of a rhodium hydride complex, such as 2a. The
high-field signal is typical for a hydride situated trans to a vacant
coordination site and suggests a square pyramidal environment
of the metal center with the hydride ligand in the apical position.
Exclusive formation of 2a was achieved by slow addition of
an equimolar amount of hydrochloric acid (∼0.4 M in dioxane)
to a THF solution of 1a at -35 °C. Interestingly, when a second
equivalent or an excess (∼10 equiv) of hydrochloric acid (∼4.0
M in dioxane) was added to THF solutions of 2a (or to reaction
mixtures, which consist of 1a, 2a, and 3a) the dichloro
rhodium(III) complex [(C10H5(CH2PiPr2)2)Rh(Cl)2(dioxane)]2
(3a) was exclusively formed and isolated in high yield. The
formation of 3a is accompanied by dihydrogen evolution.
Formation of dihydrogen was confirmed by NMR spectroscopy:
(12) Isomerization of an initially formed octahedral trans complex to a
cis-dihydride and/or mechanisms with the involvement of σ-arenium
intermediates (see also ref 17) are expected to have higher barriers.
(13) (a) Cotton, F. A.; Dikarev, E. V.; Stiriba, S.-E. Inorg. Chem. 1999,
38, 4877. (b) Pelagatti, P.; Bacchi, A.; Bobbio, C.; Carcelli, M.; Costa, M.;
Pelizzi, C.; Vivorio, C. Organometallics 2000, 19, 5440.
(14) (a) Hoogervorst, W. J.; Goubitz, K.; Fraanje, J.; Lutz, M.; Spek,
A. L.; Ernsting, J. M.; Elsevier, C. J. Organometallics 2004, 23, 4550. (b)
Agaskar, P. A.; Cotton, F. A.; Falvello, L. R.; Han, S. J. Am. Chem. Soc.
1986, 108, 1214. (c) Weller, A. S.; Mahon, M. F.; Steed, J. W. J. Organomet.
Chem. 2000, 614, 113. (d) Cotton, F. A.; Kim, Y. Eur. J. Solid State Inorg.
Chem. 1994, 31, 525. (e) de Bruin, B.; Boerakker, M. J.; Donners, J. J. J. M.;
Christiaans, B. E. C.; Schlebos, P. P. J.; de Gelder, R.; Smits, J. M. M.;
Spek, A. L.; Gal, A. W. Angew. Chem., Int. Ed. 1997, 36, 2064. (f)
Crawford, C. A.; Matonic, J. H.; Streib, W. E.; Huffman, J. C.; Dunbar,
K. R.; Christou, G. Inorg. Chem. 1993, 32, 3125. (g) Cotton, F. A.; Dikarev,
E. V.; Petrukhina, M. A. J. Chem. Soc., Dalton Trans. 2000, 4241. (h)
Bonar-Law, R. P.; Bickley, J. F.; Femoni, C.; Steiner, A. J. Chem. Soc.,
Dalton Trans. 2000, 4244.
2
A sharp singlet at δ ) 4.40 ppm was detectable in the H
spectrum when THF solutions of 1a were treated with an excess
(∼2.5 equiv) of deuterium chloride (∼1.0 M in diethyl ether).
Dihydrogen generation along the synthesis of 3a implies a direct
attack of the proton on the hydride ligand of 2a, since attack at
(8) Gandelman, M.; Konstantinovski, L.; Rozenberg, H.; Milstein, D.
Chem.-Eur. J. 2003, 9, 2595.
(9) (a) Budzelaar, P. H. M.; de Gelder, R.; Gal, A. W. Organometallics
1998, 17, 4121. (b) Alvarez, S. Coord. Chem. ReV. 1999, 13, 193–195.
(10) (a) Fekl, U.; Kaminsky, W.; Goldberg, K. I. J. Am. Chem. Soc.
2001, 123, 6423. (b) Reinartz, S.; White, P. S.; Brookhart, M.; Templeton,
J. L. J. Am. Chem. Soc. 2001, 123, 6425.
(11) Frech, C. M.; Ben-David, Y.; Weiner, L.; Milstein, D. J. Am. Chem.
Soc. 2006, 128, 7128.

1902 Organometallics, Vol. 28, No. 6, 2009
Frech et al.
2
Partial liberation of the metal-coordinated dioxane molecule
of 3a was observed under reduced pressure, most probably
yielding their pentacoordinated solvent-free dichloro complexes.
However, when an excess (∼50 equiv relative to rhodium) of
CO gas was added to methylene chloride solutions of 3a
quantitative substitution of dioxane to give the mononuclear
carbonyl derivative [(C10H5(CH2PiPr2)2)Rh(CO)(Cl)2] (4a) was
observed. The IR spectrum of 4a exhibits a characteristic
carbonyl absorption band at 1949 cm-1. The 31P{1H} NMR
spectrum of 4a displays two signals with dd (AB) pattern
centered at δ ) 64.45 and 62.56 ppm with coupling constants
pattern at δ ) -27.42 ppm (1JRhH ) 44.2 and JPH ) 8.0 Hz),
characteristic for hydride ligands situated trans to a vacant
coordination site. The exclusive formation of 2b is unexpected,
since the higher electron density on the metal center of 1b (as
compared to 1a) would favor the electrophilic attack on the
hydride ligand.15 1b toward hydrochloric acid is attributed to
steric effects, which lead to a weaker Rh-Cl interaction in 2b.
This in turn could result in a stronger Rh-H bond preventing
liberation of dihydrogen from 2b in acidic media. This anticipa-
tion was supported by an experiment in which THF solutions
of 1a and 1b were reacted with equimolar amounts or an excess
(∼5 equiv) of 57% HBF4 · Et2O, resulting in exclusive formation
of the hydrido rhodium(III) complexes [(C10H5(CH2PR2)2)Rh(H)-
(F-BF3)] (9a and 9b) in both systems. The 31P{1H} NMR
spectrum of 9a recorded in C6D6 displays two signals with a
dd (AB) pattern at δ ) 67.23 and 65.97 ppm with coupling
constants of 1JRhP ) 113.4 and 2JPP ) 11.8 Hz for both signals.
The 1H NMR spectrum exhibits a broad hydride signal with dt
pattern at δ ) -24.32 ppm (1JRhH ) 46.4 and 2JPH ) 12.4 Hz).
Coordination of the counteranion was indicated by 19F{1H}
NMR spectroscopy, which exhibits a very broad singlet at δ )
-158.35 ppm. Free BF4 gives rise to a sharp signal at δ ≈
-152.60 ppm.18 Coordination of BF4 counteranions was already
observed in related rhodium methyl complexes, having an
important effect with regard of the stabilization of the Rh-CH3
bond.8,15,17 The 31P{1H} NMR spectrum of 9b exhibits a signal
with a dd pattern at δ ) 74.21 ppm and coupling constants of
2
1
of JPP ) 312.6 and JRhP ) 85.5 Hz for both signals. The
13C{1H} NMR spectrum gave rise to a signal with dd pattern at
2
δ ) 187.92 ppm with coupling constants of JPC ) 40.2 and
1JRhC ) 8.1 Hz. Attempts to selectively abstract one of the
chloride ligands of 3a with an equimolar amount of silver salts,
such as AgBF4 or AgBArF , led to inseparable mixtures, which
4
consist of 3a and several other unidentified phosphorus-
containing compounds. Complete decomposition was obtained
when g2 equiv (relative to rhodium) of a silver salt was added
to methylene chloride solutions of 3a and 4a, respectively.
Similarly, the addition of an equimolar amount (relative to
rhodium) of methyl lithium (∼1.6 M in diethyl ether) to
methylene chloride solutions of 3a at room temperature yielded
an inseparable mixture of phosphorus-containing products. The
presence of the methyl chloride complex [(C10H5(CH2PiPr2)2)-
Rh(CH3)(Cl)] (5a) in this reaction mixture (∼28%) was
established by 31P{1H} and 13C{1H} NMR spectroscopy. For
instance, the 31P{1H} NMR spectrum exhibits two signals
centered at δ ) 47.12 and 47.47 ppm with dd (AB) pattern and
1JRhP ) 120.1 and JPP ) 24.5 Hz. The H NMR spectrum
2
1
showed a broad doublet of triplet at δ ) -27.27 ppm (1JRhH
)
2
53.8 and JPH ) 12.6 Hz). Alternative syntheses of 9a and 9b
were achieved by the addition of equimolar amounts of AgBF4
to methylene chloride solutions of 2a and 2b under rigorous
exclusion of light. On the other hand, when an equimolar amount
of AgBArF4 was added to methylene chloride (or diethyl ether)
solutions of 2a and 2b the cationic, solvent-stabilized rhodium
1
2
coupling constants of JRhP ) 116.2 and JPP ) 52.4 Hz. The
13C{1H} NMR spectrum exhibits a signal with dt pattern at δ
) -4.72 ppm and coupling constants of 1JRhC ) 31.2 and 2JPC
) 5.2 Hz, which is in the chemical shift range characteristic
for metal-coordinated methyl groups of complexes of type 5a.
Indeed, the NMR data compare well with those of its methyl
iodide derivative [(C10H5(CH2PiPr2)2)Rh(CH3)(I)]15 (6a). Further
evidence for the identity of 5a was gained by the addition of a
slight excess (∼1.2 equiv relative to rhodium of 3a) of AgBF4
to that reaction mixture under rigorous exclusion of light, which
yielded the BF4-coordinated complex [(C10H5(CH2PiPr2)2)-
Rh(CH3)(F-BF3)] (7a) in approximately 27% yield (by integra-
tion). The identity of 7a was confirmed by its independent
synthesis, achieved by treatment of methylene chloride solutions
of 6a with an equimolar amount of AgBF4. Upon treatment with
CO, 7a underwent methyl migration to the Cipso, exclusively
forming the η2 C-C agostic complex [(C10H5(CH2PiPr2)2)-
(CH3)Rh(CO)][BF4] (8a), similar to the reactivity pattern of
related rhodium pincer complexes.13,15-17
hydride complexes [(C10H5(CH2PR2)2)Rh(solv)(H)][BArF ] (10a
4
and 10b) were formed. Their 31P{1H} NMR spectra exhibit very
broad signals at δ ) 63.13 and 76.94 ppm at room temperature,
most probably as a consequence of the labile coordination of
the solvent molecules. Indeed, when the 31P{1H} NMR spectra
were recorded at -70 °C, the signals sharpened and exhibited
broad dd-like patterns, as expected. Migration of the hydride
ligands to the aromatic ring was not observed, as indicated by
1H and 13C{1H} NMR spectroscopy. For instance, in the H
1
NMR spectra broad doublets at δ ) -20.04 (for 10a) and
-27.18 ppm (for 10b) with coupling constants of 1JRhH ) 52.6
and 1JRhH ) 55.4 Hz, respectively, were detected. The 13C{1H}
NMR spectra exhibit broad singlets at δ ) 160.21 and 164.42
ppm, respectively, which are attributed to the σ bound Rh-Cipso
carbon atoms of the pincer core. Coordination of a solvent
molecule to the metal centers of 10a and 10b was confirmed
Remarkably, in striking difference to the reactivity pattern
of 1a, treatment of THF solutions of the bulky tBu derivative
1b with an equimolar amount or even a large excess (∼25 equiv)
of hydrochloric acid (∼4.0 M in dioxane) exclusively yielded
the hydrido chloro complex [(C10H5(CH2PtBu2)2)Rh(Cl)(H)]
(2b). The formation of dichloro RhIII complexes was not
obtained. The 31P{1H} NMR spectrum of 2b exhibits two signals
with dd (AB) pattern centered at δ ) 74.12 and 74.04 ppm.
Their coupling constants are 1JRhP ) 114.4 and 2JPP ) 34.2 Hz,
respectively. The presence of a Rh-H bond was established
by 1H NMR spectroscopy, displaying an intense signal with dt
by H and 13C{1H} NMR spectroscopy (as well as elemental
analysis in the case of THF). For instance, when the H and
1
1
13C{1H} NMR spectra of dry 10a and 10b (prepared in
methylene chloride) were recorded in THF-d8, signals due to
an equimolar amount (by integration) of “free” methylene
chloride were detected, indicating that a coordinated methylene
chloride molecule was substituted by a molecule of THF.
Similarly, when the NMR spectra of dry 10a and 10b (prepared
in diethyl ether) were recorded in CD2Cl2, signals due to a
corresponding amount of “free” diethyl ether were detected.
These findings are interesting, since methylene chloride is
(15) Frech, C. M.; Milstein, D. J. Am. Chem. Soc. 2006, 128, 12434.
(16) See the Experimental Section.
(17) Vigalok, A.; Rybtchinski, B.; Shimon, L. J. W.; Ben-David, Y.;
Milstein, D. Organometallics 1999, 18, 895.
(18) See, for instance, 31F{1H} NMR data of 11a′ in the Experimental
Section.

Unsaturated Rh(I) and Rh(III) PCP Complexes
Organometallics, Vol. 28, No. 6, 2009 1903
of the hydrido dicarbonyl rhodium complex [(C10H5(CH2PiPr2)2-
Rh(H)(CO)2][BF4] (13a) was observed. 13a is stable under CO
atmosphere (∼1.5 atm) but readily loses a carbonyl ligand (to
form 11a′) under N2 atmosphere or under reduced pressure.
C-H activation to form the hydride complex 13a became
evident by 1H and 13C{1H} NMR spectroscopy. For instance, a
1
broad hydride signal appeared at -7.88 ppm in the H NMR
spectrum. In the 13C{1H} NMR spectrum, two signals with dvt
pattern at δ ) 184.43 (1JRhP ) 40.7 and JPC ) 6.8 Hz) and
183.87 ppm (1JRhP ) 42.1 and JPC ) 7.1 Hz) were detected,
which were assigned to the carbonyl ligands. In addition, a
doublet due to the Cipso carbon atom at δ ) 146.42 ppm (1JRhC
) 22.5 Hz) was detectable. In analogy to the literature example
mentioned above, no spectroscopic evidence for the formation
of the hydrido rhodium(III) dicarbonyl complex 13b was
observed in the case of the bulky tBu derivative 11b′.
Figure 1. DIAMOND drawing of a molecule of 3a, showing the
atom labeling scheme (50% probability). Hydrogen atoms are
omitted for clarity. Selected bond distances (Å) and angles (deg):
Rh1-C12 ) 2.014(4), Rh1-P1 ) 2.3611(11), Rh1-P2 )
2.3447(11), Rh1-Cl1 ) 2.3600(11), Rh1-Cl2 ) 2.3467(11),
Rh1-O1 ) 2.371(3); P1-Rh1-P2 ) 163.46(4), Cl2-Rh1-Cl2
) 174.39(4), C12-Rh1-O1 ) 172.39(13).
Similar to the reactivity pattern of [(C10H5(CH2PiPr2)2)-
Rh(CH3)(I)] (6a), where formation of an isomeric mixture of
its carbonyl adducts was obtained by treatment with CO gas,15
both isomeric forms of [(C10H5(CH2PtBu2)2)Rh(H)(Cl)(CO)] 14b
(CO trans to the hydride ligand) and 14b′ (CO trans to the
aromatic pincer core) were obtained when CO gas was added
to methylene chloride solutions of 2b (Scheme 2). This is in
sharp contrast to the reactivity pattern of its methyl iodide
derivative 6b, where slow, quantitative reductive elimination
of methyl iodide to form the carbonyl complex [(C10H5-
(CH2PtBu2)2)Rh(CO)] (12b) took place by treatment with an
excess (∼100 equiv) of CO gas. The reactivity difference of
2b with respect to that of 6b indicates that reductive elimination
of methyl iodide from 6b to form 12b is induced by steric
effects. When the reaction of 2b with CO gas was performed
at -50 °C, 14b was exclusively formed, indicating that it is
the kinetic product. Upon warming to room temperature, an
equilibrium mixture of 14b (31%) and 14b′ (69%) was formed
within a few minutes, which did not change upon cooling to
-50 °C. Exclusive formation of 14b′ was obtained when 12b
was treated with an equimolar amount of hydrochloric acid
(∼4.0 M in dioxane) at -50 °C. Warming the reaction mixture
to room temperature yielded again the equilibrium mixture of
14b (31%) and 14b′ (69%). The 31P{1H} NMR spectrum of
that mixture exhibits two sets of signals with dd (AB) pattern.
The signals assigned to 14b′ are centered at δ ) 95.21 and
considered one of the weakest ligands and, hence,3a its
coordination to late transition-metals complexes is extremely
rare.2,8,19 Thus, 10a and 10b can be viewed as highly unsaturated
solvent-stabilized Rh(III) 14e- intermediates.2,4,8-10,20 To con-
clude, the choice of the counteranion (BArF or BF4) controls
4
the mode of stabilization of the metal center, either by the anion
(9a and 9b) or by the solvent (10a and 10b) (Scheme 2). If the
electron density of the metal centers of 9 (and 10) is reduced
further by substitution of the coordinated anion of 9 (or the
solvent molecule of 10) with a carbonyl ligand, instant migration
of the hydride ligand to the aromatic unit to yield the stable
carbonyl complexes of type of [(C10H5(CH2PR2)2(H)Rh(CO)][X]
(X ) BArF 11a, 11b; X ) BF4 11a′, 11b′) with η2 Caryl-H
4
agostic interactions was observed. Strongly related literature
examples for migration of hydride or methyl groups from the
metal center to the aryl ligand are known.15,17,21 The 31P{1H}
NMR spectra of 11a and 11a′ as well as those of 11b and 11b′
are identical and exhibit signals with dd (AX) pattern at δ ≈
1
35.5 (2JPP ≈ 248 and JRhP ≈ 105 Hz) and 16.8 ppm (2JPP
≈
248 and JRhP ≈ 104 Hz) as well as at δ ≈ 47.6 (2JPP ≈ 247
1
and JRhP ≈ 103 Hz) and 30.9 ppm (2JPP ≈ 247 and JRhP
≈
1
1
100 Hz), respectively. The 1H NMR spectra display, in addition
to all the signals due to the naphthalene-based pincer ligand,
doublets at δ ≈ 3.9 ppm with coupling constants of 1JRhH ≈ 11
(for 11a and 11a′) and 1JRhH ≈ 17 Hz (for 11b and 11b′), which
are attributed to the η2 Caryl-H hydrogen atoms. η2 Caryl-H
carbon atoms give rise to singlets at δ ≈ 110 ppm in the 13C{1H}
NMR spectra. The significant upfield shifts (∆δ ≈ -55 ppm)
in the 13C{1H} NMR spectra of 9 (and 10) as compared with
that of 11 (and 11′) is typical of such structural changes.16,19
Alternative syntheses of 11 and 11′ were achieved by the
addition of equimolar amounts 57% HBF4 · Et2O and [H(Et2O)2]-
2
94.15 ppm and have coupling constants of JPP ) 315.4 and
1JRhP ) 98.4 Hz, while those belonging to 14b are centered at
2
δ ) 86.74 and 86.44 ppm and have coupling constants of JPP
1
1
) 328.8 and JRhP ) 104.5 Hz. The hydride ligands in the H
NMR spectrum exhibit two doublets of triplet signals and are
positioned at δ ) -15.32 and -7.64 ppm. The signal centered
at δ ) -15.32 ppm belongs to 14b′, whereas the signal at δ )
-7.64 ppm was assigned to 14b. The coupling constants of these
[BArF ], respectively, to etheral solutions of [(C10H5(CH2PR2)2-
hydride signals are 2JPH ) 9.1 and 1JRhH ) 4.2 Hz and 1JRhH
)
4
8.6 and 2JPH ) 8.4 Hz, respectively. The substantial difference
in the chemical shifts indicates different ligands trans to the
Rh-H bond. The isomeric nature of 14b and 14b′ was
confirmed by treatment of its methylene chloride solutions with
Rh(CO)] (12a and 12b). As observed with the phenyl-based
analogue of 11a′,21 upon treatment with CO exclusive formation
(19) (a) Arndtsen, B. A.; Bergman, R. G. Science 1995, 270, 1970. (b)
Butts, M. D.; Scott, B. L.; Kubas, G. J. J. Am. Chem. Soc. 1996, 118, 11831.
(c) Kimmich, B. F. M.; Bullock, R. M. Organometallics 2002, 21, 1504.
(d) The first example of CH2Cl2 coordination to RhIII was published
recently: Taw, F. L.; White, P. S.; Bergman, R. G.; Brookhart, M. J. Am.
Chem. Soc. 2002, 124, 4192.
(20) (a) Rybtchinski, B.; Konstantinovsky, L.; Shimon, L. J. W.; Vigalok,
A.; Milstein, D. Chem.-Eur. J. 2000, 6, 3208. (b) Montag, M.; Leitus, G.;
Shimon, L. J. W.; Ben-David, Y.; Milstein, D. Chem.-Eur. J. 2007, 13,
9043. (c) Dorta, R.; Goikhman, R.; Milstein, D. Organometallics 2003,
22, 2806.
AgBArF and AgBF4, which cleanly yielded 11b and 11b′,
4
respectively. In contrast, when an excess of CO gas was added
to THF (or methylene chloride), solutions of 2a and 14a′ were
exclusively formed within 20 min at room temperature. The
same result was obtained by treatment of THF solutions of 12a
with an equimolar amount of hydrochloric acid (∼4.0 M in
dioxane). The exclusive formation of 14a′ is attributed to steric
effects; the iPr substituents of 14a′ apparently allow Rh-Cl
interactions trans to the hydride ligand which are stronger when
(21) Montag, M.; Schwartsburd, L.; Cohen, R.; Leitus, G.; Ben-David,
Y.; Martin, J. M.; Milstein, D. Angew. Chem., Int. Ed. 2007, 46, 1901.

1904 Organometallics, Vol. 28, No. 6, 2009
Frech et al.
Scheme 2. Reactions of 1b with Hydrochloric Acid and Subsequent Reactions
and stored over activated 4 Å molecular sieves in the glove-
box. All the commercial available chemicals were used as received.
Analysis. 1H, 13C{1H}, 31P{1H}, and 19F NMR data were recorded
at 500.13, 125.76, 202.46, and 235.40 MHz, respectively, on a
Bruker DRX-500 spectrometer. Chemical shifts (δ) are expressed
in parts per million (ppm), and coupling constants (J) are in hertz.
The 1H and 13C NMR chemical shifts are relative tetramethylsilane;
the resonances of the residual protons of the solvents were used as
internal standard for 1H (δ 7.15 (C6D6); 7.26 (CDCl3); 5.32
(CD2Cl2); 3.58 and 1.73 ppm (THF)) and all-d solvent peaks for
13C (δ 128.0 (C6D6); 77.0 (CDCl3); 53.8 (CD2Cl2); 68.00 and 25.77
ppm (THF)). 31P NMR chemical shifts are reported downfield
relative to external 85% H3PO4 in D2O at δ ) 0.0 ppm. All
measurements were carried out at 298 K. Abbreviations used in
the description of NMR data are as follows: b, broad; s, singlet; d,
doublet; t, triplet; q, quartet; m, multiplet; v, virtual. Elemental
analyses were performed by H. Kolbe, Mikroanalytisches Labora-
torium, Germany, and at the Department of Inorganic Chemistry
at the University of Zurich.
compared with the more bulky tBu derivative 14b′ (see also
the explanation of the reactivity difference of 1a and 1b toward
hydrochloric acid). However, the 31P{1H} NMR spectrum of
14a′ shows a signal with a dd pattern centered at δ ) 79.03
2
and 78.44 ppm with coupling constants of JPP ) 320.4 and
1JRhP ) 97.1 Hz. The 1H NMR spectrum exhibits a sharp doublet
of triplet at -14.89 ppm (2JPH ) 27.0 Hz and 1JRhH ) 9.4 Hz).
Treatment of its methylene chloride solutions with AgBArF4 and
AgBF4 cleanly yielded 11a and 11a′, respectively. Unexpectedly,
14a′ is not stable in solution. Methylene chloride solutions of
14a′ led to the precipitation of a yellow, insoluble microcrys-
talline solid overnight. Similarly, when 14a′ was dissolved in
THF its conversion into new species (signals centered at δ )
42.77 ppm were detected in the 31P{1H} NMR spectrum) was
observed overnight. Neither a signal attributable to a rhodium-
hydride bond nor evidence for migration of the hydride ligand
1
to the aromatic pincer core was obtained by H and 13C{1H}
NMR spectroscopy. Furthermore, precipitation of a yellow,
insoluble microcrystalline solid was observed within a few days
in THF, indicating that probably cluster formation occurred,
formation of which might be retarded in a coordinating solvent
such as THF when compared with methylene chloride. The
identity of the product(s) could not be determined.
In conclusion, seemingly very similar rhodium pincer com-
plexes show significantly different reactivity modes that are
controlled by steric effects. Furthermore, the synthesis of highly
unsaturated 14-electron Rh d6 complexes was described, and
the complexes are, depending on the steric bulk of the
counteranion, stabilized either by coordination of a solvent
molecule or by the counteranion.
Preparation of [(C10H5(CH2P(iPr2)2)Rh(H)(Cl)] (2a). To a
cooled (-35 °C) THF solution (10 mL) of [(C10H5(CH2PiPr2)2)-
Rh(η1-N2)]2 (25 mg, 0.025 mmol), an equimolar amount of
hydrochloric acid (∼0.4 M in dioxane) was added and stirred for
15 min. The solvent was removed under reduced pressure. The
product was extracted (2 × 5 mL) with diethyl ether. The solvent
was removed under reduced pressure, yielding 20.4 mg (0.039
mmol, 78%) of pure 2a. 2a was also obtained when an equimolar
amount of LiHBEt3 (∼1 M in THF) was added to a cooled (–35
°C) THF solution (10 mL) of [(C10H5(CH2PiPr2)2)Rh(dioxane)]2 (30
mg, 0.025 mmol) and stirred for 15 min.
2
31P{1H} NMR (C6D6; δ, ppm): 64.46 (dd (AB), JPP ) 396.2
1
2
1
Hz, JRhP ) 117.5 Hz), 64.00 (dd (AB), JPP ) 396.2 Hz, JRhP
)
1
117.5 Hz). H NMR (δ, ppm): 7.85 (d, JHH ) 7.1 Hz, 1H, Ar),
7.71 (d, JHH ) 7.2 Hz, 1H, Ar), 7.69 (s, 1H, Ar), 7.34 (m, 2H, Ar),
3.53 (dd, JPH ) 14.8 Hz, JRhH ) 9.8 Hz, 1H, CH2P), 3.34 (dd, JPH
) 14.7 Hz, JRhH ) 6.9 Hz, 1H, CH2P), 3.27 (dd, JPH ) 14.9 Hz,
JRhH ) 6.9 Hz, 1H, CH2P), 2.96 (dd, JPH ) 14.8 Hz, JRhH ) 9.8
Hz, 1H, CH2P), 2.77 (m, 1H, PCH(CH3)2), 2.64 (m, 1H,
PCH(CH3)2), 2.34 (m, 2H, PCH(CH3)2), 1.31 (m, 24H, PCH(CH3)2),
Experimental Section
General Procedures. All synthetic operations were carried out
in oven-dried glassware under an atmosphere of purified nitrogen
in a Vacuum Atmospheres glovebox equipped with a MO 40-2
inert gas purifier. Solvents were reagent grade or better, dried,
distilled, and degassed before introduction into the glovebox, where
they were stored over activated 4 Å molecular sieves. Deuterated
solvents were purchased from Aldrich or Armar and were degassed
1
2
-24.53 (dt, JRhH ) 44.6 Hz, JPH ) 7.8 Hz, 1H, RhH). 13C{1H}
NMR (δ, ppm): 160.54 (d, J ) 30.1 Hz, Cipso), 148.18 (dd, JPC
)

Unsaturated Rh(I) and Rh(III) PCP Complexes
Organometallics, Vol. 28, No. 6, 2009 1905
12.8 Hz, JRhC ) 6.4 Hz, Ar), 144.35 (dd, JPC ) 12.9 Hz, JRhC
)
yellow. After filtration over a cotton pad, the solvent was removed
under reduced pressure, and the residue was washed with pentane
(2 × 5 mL) and dried again. 5a was obtained in 28.0 mg (0.048
mmol, >98%) as a yellow solid.
6.3 Hz, Ar), 131.91 (s, Ar), 129.23 (s, Ar), 128.15 (s, Ar), 127.00
(s, Ar), 125.59 (s, Ar), 124.43 (s, Ar), 121.40 (d, J ) 11.8 Hz, Ar),
33.63 (d, J ) 16.9 Hz, CH2P), 30.31 (d, J ) 16.9 Hz, CH2P), 25.21
(dd, J ) 24.2 Hz, J ) 2.3 Hz, PCH(CH3)2), 24.75 (dd, J ) 26.5
Hz, J ) 3.1 Hz, PCH(CH3)2), 19.05 (m, PCH(CH3)2), 18.78 (m,
PCH(CH3)2). Elemental analysis calcd for C24H38ClP2Rh: C, 54.71;
H, 7.27. Found: C, 55.00; H, 7.47.
2
31P{1H} NMR (CDCl3; δ, ppm): 64.45 (dd (AB), JPP ) 312.6
1
2
1
Hz, JRhP ) 85.5 Hz), 62.56 (dd (AB), JPP ) 312.6 Hz, JRhP
)
1
85.5 Hz). H NMR (δ, ppm): 7.86 (broad s, 1H, Ar), 7.73 (broad
s, 1H, Ar), 7.62 (broad s, 1H, Ar), 7.43 (m, 2H, Ar), 4.02 (d, J )
8.0 Hz, 2H, CH2P), 3.84 (d, J ) 8.1 Hz, 2H, CH2P), 3.78 (m, 1H,
PCH(CH3)2), 3.66 (m, 1H, PCH(CH3)2), 2.93 (m, 1H, PCH(CH3)2),
2.82 (m, 1H, PCH(CH3)2), 1.45 (m, 24H, PCH(CH3)2). 13C{1H}
NMR (δ, ppm): 187.92 (dt, J ) 40.2 Hz, J ) 8.1 Hz, CO), 163.31
(broad d, J ) 21.1 Hz, Cipso), 143.86 (dd, J ) 13.4 Hz, J ) 3.3
Hz, Ar), 140.96 (dd, J ) 13.8 Hz, J ) 3.4 Hz, Ar), 132.72 (s, Ar),
128.88 (s, Ar), 128.05 (s, Ar), 125.33 (s, Ar), 124.59 (s, Ar), 124.37
(s, Ar), 122.35 (d, J ) 16.2 Hz, Ar), 36.59 (d, J ) 29.6 Hz, CH2P),
33.20 (d, J ) 31.8 Hz, CH2P), 24.83 (dd, J ) 19.2 Hz, J ) 4.2
Hz, PCH(CH3)2), 24.23 (dd, J ) 15.7 Hz, J ) 4.1 Hz, PCH(CH3)2),
20.12 (s, PCH(CH3)2), 20.08 (s, PCH(CH3)2), 19.36 (s, PCH(CH3)2),
19.07 (s, PCH(CH3)2). IR (film; cm-1) ν 1949 cm-1 (s, CO).
Elemental analysis calcd for C25H37Cl2OP2Rh: C, 50.95; H, 6.33.
Found: C, 51.08; H, 6.42.
Preparation of [(C10H5(CH2P(tBu2)2)Rh(H)(Cl)] (2b). To a
THF solution (5 mL) of [(C10H5(CH2P(tBu2)2)Rh(η1-N2)] (20 mg,
0.034 mmol) a slight excess (∼1.5 equiv) of hydrogen chloride
(∼4 M in dioxane) was added, which was accompanied by a color
change from brown to bright yellow. The solvent was removed
under reduced pressure. The residue was washed with pentane (2
× 5 mL). Extraction of 2b with methylene chloride yielded 20.5
mg (0.033 mmol, >98%) of 2b as a bright yellow solid.
31P{1H} NMR (CD2Cl2; δ, ppm): 74.12 (dd (AB), 1JRhP ) 114.4
2
1
2
Hz, JPP ) 34.2 Hz), 74.04 (dd (AB), JRhP ) 114.4 Hz, JPP
)
1
34.2 Hz). H NMR (δ, ppm): 7.91 (d, J ) 8.0 Hz, 1H, Ar), 7.69
(d, J ) 8.0 Hz, 1H, Ar), 7.54 (s, 1H, Ar), 7.39 (m, 2H, Ar), 3.66
(m, ∼6H, CH2P overlapped with the signal of some dioxane), 3.45
(ddd, J ) 44.5 Hz, J ) 15.7 Hz, J ) 3.6 Hz, 2H, CH2P), 1.42 (m,
36H, PC(CH3)3), -27.42 (dt, J ) 44.2 Hz, J ) 8.0 Hz, 3H, RhH).
13C{1H} NMR (δ, ppm): 161.02 (ddd, J ) 32.2 Hz, J ) 5.2 Hz, J
) 2.5 Hz, Cipso), 149.88 (ddd, J ) 11.8 Hz, J ) 7.2 Hz, J ) 0.8
Hz, Ar), 146.54 (ddd, J ) 12.0 Hz, J ) 8.1 Hz, J ) 0.8 Hz, Ar),
131.49 (s, Ar), 127.75 (s, Ar), 126.63 (s, Ar), 125.11 (s, Ar), 124.13
(s, Ar), 123.96 (s, Ar), 120.51 (dd, J ) 10.1 Hz, J ) 5.0 Hz, Ar),
36.47 (ddd, J ) 28.4 Hz, J ) 9.4 Hz, J ) 6.1 Hz, PC(CH3)3),
34.76 (ddd, J ) 16.2 Hz, J ) 6.3 Hz, J ) 1.9 Hz, PC(CH3)3),
34.35 (ddd, J ) 18.6 Hz, J ) 6.2 Hz, J ) 2.0 Hz, CH2P), 30.75
(ddd, J ) 18.9 Hz, J ) 5.3 Hz, J ) 3.1 Hz, CH2P), 29.89 (vt, J )
2.1 Hz, PC(CH3)3), 29.54 (vt, J ) 3.0 Hz, PC(CH3)3), 29.45 (vt, J
) 2.0 Hz, PC(CH3)3), 29.18 (vt, J ) 3.0 Hz, PC(CH3)3). Elemental
analysis calcd for C28H46ClP2Rh: C, 57.69; H, 7.95. Found: C,
57.56; H, 8.06.
Preparation of [(C10H5(CH2PiPr2)2Rh(CH3)(F-BF3)] (7a). To
a solution of [(C10H5(CH2PiPr2)2)Rh(CH3)(I)] (25 mg, 0.050 mmol)
in 5 mL of methylene chloride, 1 equiv of AgBF4 (9.6 mg, 0.0540
mmol) was added. After 15 min, the reaction mixture was filtered
through celite, and the solvent was removed under reduced pres-
sure. The residue was washed with pentane (2 × 5 mL) and dried
again. The product was obtained as a red-brown solid in almost
quantitative yield (0.048 mmol, >95%).
1
31P{1H} NMR (CDCl3; δ, ppm): 74.12 (dd, JRhP ) 120.2 Hz,
2JPP ) 47.1 Hz). 1H NMR (δ, ppm): 7.82 (d, J ) 7.3 Hz, 1H, Ar),
7.75 (d, J ) 7.3 Hz, 1H, Ar), 7.46 (m, 2H, Ar), 7.36 (s, 1H, Ar),
3.38 (dd, J ) 7.3 Hz, J ) 3.1 Hz, 1H, CH2P), 2.91 (m, 2H, CH2P),
2.83 (dd, J ) 7.3 Hz, J ) 3.0 Hz, 1H, CH2P), 2.79 (m, 1H,
PCH(CH3)2), 2.66 (m, 1H, PCH(CH3)2), 2.17 (dist sixt, J ) 2.1
Hz, 1H, PCH(CH3)2), 2.08 (dist sixt, J ) 2.1 Hz, 1H, P-CH(CH3)2),
1.56 (broad s, 3H, Rh-CH3), 1.26 (m, 12H, PCH(CH3)2), 1.17 (m,
6H, PCH(CH3)2), 0.92 (m, 6H, PCH(CH3)2). 13C{1H} NMR (δ,
ppm): 152.18 (dt, J ) 39.2 Hz, J ) 6.7 Hz, Cipso), 147.67 (broad
s, Ar), 146.18 (broad s, Ar), 132.08 (s, Ar), 129.06 (s, Ar), 126.68
(s, Ar), 125.42 (s, Ar), 124.67 (s, Ar), 123.92 (s, Ar), 122.09 (d, J
) 11.5 Hz, Ar), 29.96 (broad s, CH2P), 26.83 (broad s, CH2P),
24.73 (dt, J ) 28.8 Hz, J ) 8.7 Hz, PCH(CH3)2), 23.95 (dt, J )
28.9 Hz, J ) 8.8 Hz, PCH(CH3)2), 20.00 (s, PCH(CH3)2), 19.70
(s, PCH(CH3)2), 18.64 (s, PCH(CH3)2), 18.35 (s, PCH(CH3)2), 18.03
(broad s, PCH(CH3)2), 17.68 (s, PCH(CH3)2), 17.47 (s, PCH(CH3)2),
-3.43 (broad d, J ) 28.7 Hz, RhCH3). 19F{1H} NMR (δ, ppm):
-167.7 (broad s, RhFBF3). Elemental analysis calcd for
C25H40BF4P2Rh: C, 50.70; H, 6.81. Found: C, 50.75; H, 6.43.
Preparation of [(C10H5(CH2PiPr2)2)Rh(Cl)2(dioxane)]2 (3a). To
a benzene solution (5 mL) of 45 mg (0.045 mmol) of [(C10H5(CH2-
PiPr2)2)Rh(η1-N2)], an excess (∼5 equiv) of HCl (∼4 M in dioxane)
was added, accompanied by a color change from brown to yellow-
brown. The reaction mixture was filtered over a cotton pad, and
the solvent was removed under reduced pressure. The residue was
washed with pentane (3 × 5 mL) and dried again. The product
was obtained in 44.7 mg (0.036 mmol, 82%) as a yellow-brown
solid.
31P{1H} NMR (CD2Cl2; δ, ppm): 50.75 (dd (AB), 2JPP ) 360.7,
1JRhP ) 96.2 Hz), 49.82 (dd (AB), 2JPP ) 360.7, 1JRhP ) 96.2 Hz).
1H NMR (δ, ppm): 7.41 (d, J ) 7.5 Hz, 1H, Ar), 7.32 (d, J ) 7.5
Hz, 1H, Ar), 7.00 (m, 2H, Ar), 6.87 (s, 1H, Ar), 3.72 (m, ∼4H,
CH2 of dioxane), 3.23 (d, J ) 9.8 Hz, 2H, CH2P), 3.03 (d, J ) 9.7
Hz, 2H, CH2P), 2.49 (m, 2H, PCH(CH3)2), 2.41 (m, 2H,
PCH(CH3)2), 0.96 (m, 12H, PCH(CH3)2), 0.84 (m, 12H,
PCH(CH3)2). 13C{1H} NMR (δ, ppm): 141.84 (dd, J ) 11.5 Hz, J
) 3.4 Hz, Ar), 138.99 (dd, J ) 12.6 Hz, J ) 3.4 Hz, Ar), 137.50
(dt, J ) 32.9 Hz, J ) 4.6 Hz, Cipso), 130.69 (s, Ar), 128.10 (t, J )
6.3 Hz, Ar), 124.72 (s, Ar), 123.08 (s, Ar), 122.33 (s, Ar), 121.21
(s, Ar), 120.27 (d, J ) 15.0 Hz, Ar), 67.7 (s, CH2 of dioxane),
31.25 (d, J ) 25.0 Hz, CH2P), 26.95 (d, J ) 27.3 Hz, CH2P), 22.21
(dd, J ) 16.7 Hz, J ) 3.8 Hz, PCH(CH3)2), 21.67 (dd, J ) 16.7
Hz, J ) 3.9 Hz, PCH(CH3)2), 17.54 (s, PCH(CH3)2), 17.48 (s,
PCH(CH3)2), 16.61 (s, PCH(CH3)2), 16.44 (s, PCH(CH3)2). El-
emental analysis calcd for C52H82Cl4O2P4Rh2: C, 51.59; H, 6.83.
Found: C, 51.31; H, 6.57.
Preparation of [(C10H5(CH2PiPr2)2(CH3))Rh(CO)][BF4] (8a).
To a methylene chloride solution (5 mL) of 7a (30 mg, 0.050
mmol), an excess (∼50 equiv) of CO gas was added. While the
reaction was being stirred for a few minutes, formation of 8a
occurred. The reaction mixture was filtrated through celite, and the
solvent was removed under reduced pressure. The crude product
was washed with pentane (2 × 5 mL) and dried again. The yield
of 8a was 28.6 mg (94%).
31P{1H} NMR (C6D6; δ, ppm): 23.72 (dd (AB), J ) 261.7 Hz,
J ) 101.2 Hz), -4.97 (dd (AB), J ) 261.7 Hz, J ) 101.2 Hz). 1H
NMR (δ, ppm): 8.14 (d, JHH ) 8.1 Hz, 1H, Ar), 7.83 (d, JHH ) 6.8
Hz, 1H, Ar), 7.66 (t, JHH ) 6.7 Hz, 1H, Ar), 7.62 (t, JHH ) 6.8 Hz,
1H, Ar), 7.53 (s, 1H, Ar), 4.25 (dt, J ) 13.5 Hz, J ) 4.2 Hz, 1H,
CH2P), 3.69 (dd, J ) 14.8 Hz, J ) 9.5 Hz, 1H, CH2P), 3.60 (dd,
J ) 14.8 Hz, J ) 9.5 Hz, 1H, CH2P), 3.36 (dt, J ) 14.8 Hz, J )
4.2 Hz, 1H, CH2P), 2.40 (s, 3H, ArCH3), 2.28 (m, 2H, PCH(CH3)2),
2.16 (m, 2H, PCH(CH3)2), 1.39 (m, 6H, PCH(CH3)2), 1.30 (m, 6H,
Preparation of [(C10H5(CH2PiPr2)2)Rh(CO)(Cl)2] (4a). To a
methylene chloride solution (5 mL) of 3a (30 mg, 0.024 mmol),
CO was bubbled through the reaction solution for one minute. The
color of the reaction mixture turned from yellow-brown to bright

1906 Organometallics, Vol. 28, No. 6, 2009
Frech et al.
PCH(CH3)2), 1.04 (m, 12H, PCH(CH3)2). 13C{1H} NMR (δ, ppm):
187.08 (dvt, J ) 97.7 Hz, J ) 12.5 Hz, CO), 140.3 (s, Ar), 137.28
(s, Ar), 134.83 (s, Ar), 129.50 (d, J ) 6.7 Hz, Ar), 128.89 (s, Ar),
128.31 (s, Ar), 127.24 (d, J ) 9.4 Hz, Ar), 126.47 (s, Ar), 124.90
(s, Ar), 103.48 (s, ArCH3), 26.12 (d, JPC ) 18.7 Hz, CH2P), 25.84
(d, JPC ) 22.7 Hz, PCH(CH3)2), 25.59 (d, J ) 24.1 Hz, PCH(CH3)2),
24.51 (d, J ) 18.7 Hz, PCH(CH3)2), 23.90 (d, J ) 18.7 Hz,
PCH(CH3)2), 20.29 (d, JPC ) 20.1 Hz, CH2P), 19.28 (s, PCH(CH3)2),
19.02 (s, PCH(CH3)2), 18.74 (s, PCH(CH3)2), 18.63 (s, PCH(CH3)2),
18.60 (s, PCH(CH3)2), 18.58 (s, PCH(CH3)2), 18.52 (s, PCH(CH3)2),
18.13 (s, PCH(CH3)2), 5.98 (s, ArCH3). 19F{1H} NMR (δ, ppm):
-152.60 (s, BF4). IR (film; cm-1) ν 1974 cm-1 (s, CO). Elemental
analysis calcd for C26H40BF4OP2Rh: C, 50.35; H, 6.50. Found: C,
50.14; H, 6.33.
(broad s, BF4). Elemental analysis calcd for C28H46BF4P2Rh: C,
53.02; H, 7.31. Found: C, 52.89; H, 7.16.
Preparation of [(C10H5(CH2P(iPr2)2)Rh(H)(CH2Cl2)][BArF ]
4
(10a). To methylene chloride solution (5 mL) of [(C10H5(CH2-
P(iPr2)2)Rh(H)(Cl)] (25 mg, 0.047 mmol), an equimolar amount of
AgBArF (41.6 mg, 0.047 mmol) was added. While the reaction
4
mixture was being stirred for 15 min, AgCl was precipitated. The
reaction mixture was filtrated through celite. Removal of the solvent
under reduced pressure yielded 47.4 mg (0.033 mmol, >98%) of
10a as a yellow oil. The oily residue was washed with 5 mL of
pentane. The pentane was then decanted, and the residue was dried
under reduced pressure to afford the product as a solid.
31P{1H} NMR (CD2Cl2; δ, ppm): 63.13 (very broad s). 1H NMR
(δ, ppm): 8.03 (d, J ) 8.0 Hz, 1H, Ar), 7.81 (d, J ) 8.0 Hz, 1H,
Preparation of [(C10H5(CH2P(iPr2)2)Rh(H)(F-BF3)] (9a). To
a THF solution (5 mL) of [(C10H5(CH2PiPr2)2)Rh(η1-N2)] (30 mg,
0.030 mmol), an equimolar amount of 57% HBF4 · Et2O was slowly
added. After a few minutes, the solvent was removed. The residue
was washed with diethyl ether (3 × 10 mL), extracted with
methylene chloride, and dried under vacuum to afford 28.7 mg
(0.049 mmol, 82%) of 9a as a yellow-brown solid. An alternative
synthesis is possible: The addition of an equimolar amount of
AgBF4 to methylene chloride solutions of [(C10H5(CH2PiPr2)2)-
Rh(H)(Cl)] (2a) also exclusively yielded complex 9a.
Ar), 7.62 (s overlapped by a BArF signal, 1H, Ar), 7.45 (m, 2H,
4
Ar), 3.60 (dd, JPH ) 14.8 Hz, JRhH ) 9.7 Hz, 2H, CH2P), 3.41 (dd,
JPH ) 14.9 Hz, JRhH ) 8.2 Hz, 2H, CH2P), 2.78 (m, 1H,
PCH(CH3)2), 2.61 (m, 1H, PCH(CH3)2), 2.22 (m, 2H, PCH(CH3)2),
1
1.31 (m, 24H, PCH(CH3)2), -20.04 (broad d, JRhH ) 52.6 Hz,
1H, RhH). 13C{1H} NMR (δ, ppm): 160.21 (broad s, Cipso), 148.02
(dd, JPC ) 13.2 Hz, JRhC ) 6.8 Hz, Ar), 143.89 (dd, JPC ) 13.0
Hz, JRhC ) 6.5 Hz, Ar), 133.41 (s, Ar), 120.03 (s, Ar), 126.43 (s,
Ar), 124.97 (s, Ar), 124.76 (s, Ar), 124.02 (s, Ar), 116.11 (d, J )
11.4 Hz, Ar), 38.17 (d, J ) 16.5 Hz, CH2P), 33.44 (d, J ) 16.6
Hz, CH2P), 25.89 (dd, J ) 23.8 Hz, J ) 2.1 Hz, PCH(CH3)2), 24.59
(dd, J ) 26.2 Hz, J ) 2.7 Hz, PCH(CH3)2), 18.93 (m, PCH(CH3)2),
31P{1H} NMR (CDCl3; δ, ppm): 67.23 (dd (AB), 1JRhP ) 113.4,
1
2
2JPP ) 11.8 Hz), 65.97 (dd (AB), JRhP ) 113.4, JPP ) 11.8 Hz).
1H NMR (δ, ppm): 7.78 (d, J ) 5.2 Hz, 1H, Ar), 7.64 (d, J ) 5.2
Hz, 1H, Ar), 7.41 (m, 2H, Ar), 7.37 (t, J ) 5.2 Hz, 1H, Ar), 3.45
(m, 3H, CH2P), 3.23 (dvt, J ) 31.2 Hz, J ) 7.6 Hz, 1H, CH2P),
2.79 (m, 2H, PCH(CH3)2), 2.26 (m, 2H, PCH(CH3)2), 1.25 (m, 24H,
18.75 (m, PCH(CH3)2). 19F{1H} NMR (δ, ppm): -63.33 (s, BArF ).
4
Elemental analysis of 10a obtained from THF solution: calcd for
C60H58BF24OP2Rh: C, 50.51; H, 4.10. Found: C, 50.73; H, 4.35.
Preparation of [(C10H5(CH2P(tBu2)2)Rh(H)(CH2Cl2)][BArF ]
4
(10b). To methylene chloride solution (5 mL) of [(C10H5(CH2-
1
2
PCH(CH3)2), -24.32 (dt, JRhH ) 46.4 Hz, JPH ) 12.4 Hz, 1H,
RhH). 13C{1H} NMR (δ, ppm): 160.22 (dt, J ) 36.3 Hz, J ) 6.8
Hz, Cipso), 148.46 (vt, J ) 7.2 Hz, Ar), 146.31 (dd, J ) 16.3 Hz,
J ) 8.7 Hz, Ar), 132.03 (s, Ar), 128.57 (s, Ar), 127.31 (s, Ar),
125.24 (s, Ar), 124.53 (s, Ar), 123.12 (s, Ar), 121.13 (dd, J ) 12.2
Hz, J ) 4.8 Hz, Ar), 34.17 (dd, J ) 12.6 Hz, J ) 2.8 Hz, CH2P),
33.84 (d, J ) 12.7 Hz, J ) 2.7 Hz, CH2P), 25.69 (dd, J ) 22.2
Hz, J ) 2.1 Hz, PCH(CH3)2), 24.75 (dd, J ) 22.5 Hz, J ) 2.1 Hz,
PCH(CH3)2), 18.86 (m, PCH(CH3)2), 18.58 (m, PCH(CH3)2).
19F{1H} NMR (δ, ppm): -158.35 (broad s, BF4). Elemental analysis
calcd for C24H38BF4P2Rh: C, 49.85; H, 6.62. Found: C, 50.07; H,
6.83.
P(tBu2)2)Rh(H)(Cl)] (20 mg, 0.034 mmol), an equimolar amount
of AgBArF (33.3 mg, 0.034 mmol) was added and stirred for 20
4
min. The reaction mixture was filtrated through celite. Removal of
the solvent under reduced pressure yielded 47.4 mg (0.033 mmol,
>98%) of 10b as a yellow oil. The oily residue was washed with
5 mL of pentane. The pentane was then decanted, and the residue
was dried under reduced pressure to afford the product as a solid.
31P{1H} NMR (CD2Cl2; δ, ppm): 76.94 (very broad s). 1H NMR
(δ, ppm): 7.95 (d, J ) 7.9 Hz, 1H, Ar), 7.76 (d, J ) 8.0 Hz, 1H,
Ar), 7.63 (s overlapped by a BArF signal, 1H, Ar), 7.49 (m, 2H,
4
Ar), 3.71 (d, J ) 8.0 Hz, 2H, CH2P), 3.51 (ddd, J ) 48.8 Hz, J )
16.2 Hz, J ) 8.0 Hz, 2H, CH2P), 1.36 (m, 36H, PC(CH3)3), -27.18
(broad d, J ) 55.4 Hz, 1H, RhH). 13C{1H} NMR (δ, ppm): 164.42
(broad s, Cipso), 147.14 (ddd, J ) 14.3 Hz, J ) 5.3 Hz, J ) 0.9 Hz,
Ar), 142.28 (m, Ar), 132.28 (s, Ar), 130.41 (d, J ) 8.3 Hz, Ar),
128.12 (s, Ar), 126.16 (s, Ar), 125.85 (s, Ar), 124.13 (s, Ar), 115.55
(d, J ) 11.2 Hz, Ar), 36.82 (ddd, J ) 15.1 Hz, J ) 13.3 Hz, J )
3.6 Hz, PC(CH3)3), 34.83 (ddd, J ) 18.5 Hz, J ) 13.1 Hz, J ) 3.9
Hz, PC(CH3)3), 32.41 (broad d, J ) 16.5 Hz, 2 CH2P), 30.08 (s,
PC(CH3)3), 29.72 (s, PC(CH3)3), 29.51 (s, PC(CH3)3), 29.25 (s,
Preparation of [(C10H5(CH2P(tBu2)2)Rh(H)(F-BF3)] (9b). To
a THF solution (5 mL) of [(C10H5(CH2PtBu2)2)Rh(η1-N2)] (40 mg,
0.068 mmol), an equimolar amount of 57% HBF4 · Et2O was slowly
added. After a few minutes, the solvent was removed under reduced
pressure. The residue was washed with diethyl ether (3 × 10 mL),
extracted with methylene chloride, and dried under vacuum to afford
34.1 mg (0.054 mmol, 79%) of 9b as a yellow-brown solid. An
alternative synthesis is possible: The addition of an equimolar
amount of AgBF4 to methylene chloride solutions of [(C10H5-
(CH2PtBu2)2)Rh(H)(Cl)] (2b) also exclusively yielded complex 9b.
PC(CH3)3). 19F{1H} NMR (δ, ppm): -63.26 (s, BArF ). Elemental
4
analysis of 10b obtained from THF solution: calcd for
31P{1H} NMR (C6D6; δ, ppm): 74.21 (dd, J ) 120.1 Hz, J )
C64H66BF24OP2Rh: C, 51.85; H, 4.49. Found: C, 52.07; H, 4.71.
1
Preparation of [(C10H5(CH2P(iPr2)2)(H)Rh(CO)][X] (X )
24.5 Hz). H NMR (δ, ppm): 7.90 (d, J ) 8.1 Hz, 1H, Ar), 7.74
BArF 11a, X ) BF4 11a′). To an etheral solution (5 mL) of 35
(d, J ) 8.1 Hz, 1H, Ar), 7.61 (s, 1H, Ar), 7.45 (t, J ) 8.1 Hz, 1H,
Ar), 7.42 (t, J ) 8.1 Hz, 1H, Ar), 3.76 (broad s, 2H, CH2P), 3.39
(broad s, 2H, CH2P), 1.48 (m, 18H, PC(CH3)3), 1.32 (m, 9H,
PC(CH3)3), 1.24 (m, 9H, PC(CH3)3), -27.27 (dt, J ) 53.8 Hz, J )
12.6 Hz, 1H, RhH). 13C{1H} NMR (δ, ppm): 164.83 (s, Cipso),
148.02 (vt, J ) 8.1 Hz, Ar), 146.93 (dd, J ) 16.6 Hz, J ) 9.6 Hz,
Ar), 131.90 (s, Ar), 128.60 (s, Ar), 127.77 (s, Ar), 125.64 (s, Ar),
124.85 (s, Ar), 123.47 (s, Ar), 121.31 (dd, J ) 12.4 Hz, J ) 5.0
Hz, Ar), 37.45 (dd, J ) 12.1 Hz, J ) 6.2 Hz, PC(CH3)3), 36.16
(broad t, J ) 8.3 Hz, PC(CH3)3), 35.92 (dd, J ) 12.8 Hz, J ) 7.4
Hz, CH2P), 30.58 (s, PC(CH3)3), 30.42 (s, PC(CH3)3), 28.91 (s,
PC(CH3)3), 28.84 (s, PC(CH3)3). 19F{1H} NMR (δ, ppm): -158.63
4
mg (0.067 mmol) of [(C10H5(CH2P(iPr2)2)Rh(CO)], an equimolar
amount of [H(Et2O)][BArF ] was added. A few minutes after its
4
addition, the solvent was evaporated under reduced pressure. The
residue was washed with pentane (5 × 5 mL) and dried, affording
73.4 mg (0.053 mmol, 78%) of 11a. To an etheral solution (5 mL)
of 35 mg (0.067 mmol) of [(C10H5(CH2P(iPr2)2)Rh(CO)], an
equimolar amount of 57% HBF4 · Et2O was slowly added. During
the addition, a yellow powder precipitated. The solvent was
decanted, and the residue was washed with diethyl ether (2 × 10
mL) and dried under reduced pressure to afford 36.4 mg (0.060
mmol, 89%) of 11a′ as a bright yellow solid.

Unsaturated Rh(I) and Rh(III) PCP Complexes
Organometallics, Vol. 28, No. 6, 2009 1907
Data for 11a: 31P{1H} NMR (CD2Cl2; δ, ppm): 35.52 (dd left
part of an AX system, J ) 248.2 Hz, J ) 104.5 Hz), 16.86 (dd
C61H58BF24OP2Rh: C, 50.92; H, 4.06. Found: C, 50.94; H, 4.19.
Data for 11b′: 31P{1H} NMR (CD2Cl2; δ, ppm): 47.61 (dd left part
of an AX system, J ) 247.1 Hz, J ) 102.9 Hz), 30.86 (dd right
1
right part of an AX system, J ) 248.2 Hz, J ) 103.8 Hz). H
1
part of an AX system, J ) 247.2 Hz, J ) 99.5 Hz). H NMR (δ,
NMR (δ, ppm): 8.19 (d, J ) 7.8 Hz, 1H, Ar), 7.84 (d, J ) 7.8 Hz,
1H, Ar), 7.77 (s, 1H, Ar), 7.66 (m, 2H, Ar), 3.91 (d, 1H, J ) 10.8
Hz, ArHRh), 3.73 (m, 3H, overlapping signals of CH2P), 3.37 (vtd,
1H, J ) 12.0 Hz, J ) 3.9 Hz, CH2P), 2.37 (m, 4H, PCH(CH3)2),
1.37 (m, 12H, PCH(CH3)2), 1.04 (m, 12H, PCH(CH3)2). 13C{1H}
NMR (δ, ppm): 183.95 (dt, J ) 90.5 Hz, J ) 12.1 Hz, CO), 155.74
(s, Ar), 144.12 (s, Ar), 141.80 (s, Ar), 138.86 (s, Ar), 130.80 (s,
Ar), 129.34 (s, Ar), 128.42 (d, J ) 7.8 Hz, Ar), 127.60 (d, J )
20.4 Hz, Ar), 124.42 (s, Ar), 110.13 (s, Ar), 32.07 (d, J ) 16.5 Hz,
CH2P), 30.98 (d, J ) 16.5 Hz, CH2P), 26.42 (dd, J ) 23.5 Hz, J
) 2.0 Hz, PCH(CH3)2), 24.72 (dd, J ) 24.0 Hz, J ) 2.2 Hz,
PCH(CH3)2), 19.07 (m, PCH(CH3)2), 18.42 (m, PCH(CH3)2).
ppm): 8.18 (d, J ) 8.0 Hz, 1H, Ar), 7.91 (d, J ) 8.0 Hz, 1H, Ar),
7.79 (m, 2H, Ar), 7.67 (s, 1H, Ar), 4.11 (broad t, J ) 12.1 Hz, 1H,
CH2P), 3.87 (d, J ) 16.4 Hz, 1H, ArHRh), 3.63 (ddd, J ) 36.6
Hz, J ) 20.2 Hz, J ) 8.1 Hz, 2H, CH2P), 3.46 (broad t, J ) 12.2
Hz, 1H, CH2P), 1.54 (d, J ) 14.5 Hz, 9H, PC(CH3)3), 1.50 (d, J )
14.5 Hz, 9H, PC(CH3)3), 1.25 (d, J ) 14.4 Hz, 18H, PC(CH3)3).
13C{1H} NMR (δ, ppm): 188.65 (dt, J ) 91.2 Hz, J ) 11.6 Hz,
CO), 156.298 (s, Ar), 144.60 (s, Ar), 138.81 (s, Ar), 131.52 (s,
Ar), 129.87 (s, Ar), 129.62 (d, J ) 8.0 Hz, Ar), 129.26 (s, Ar),
127.01 (d, J ) 19.3 Hz, Ar), 125.94 (s, Ar), 109.64 (s, Ar), 37.78
(dd, J ) 29.8 Hz, J ) 14.4 Hz, PC(CH3)3), 35.55 (dd, J ) 16.2
Hz, J ) 9.2 Hz, PC(CH3)3), 31.22 (d, J ) 17.5 Hz, CH2P), 29.93
(d, J ) 2.2 Hz, PC(CH3)3), 29.62 (d, J ) 3.2 Hz, PC(CH3)3), 29.20
(d, J ) 3.1 Hz, PC(CH3)3), 29.11 (d, J ) 3.4 Hz, PC(CH3)3), 26.38
(d, J ) 17.8 Hz, CH2P). 19F{1H} NMR (δ, ppm): -152.52 (s, BF4).
IR (film; cm-1) ν 1987 cm-1 (s, CO). Elemental analysis calcd for
C29H46BF4OP2Rh: C, 52.59; H, 7.00. Found: C, 52.74; H, 7.15.
19F{1H} NMR (δ, ppm): -63.31 (s, BArF ). IR (film; cm-1) ν 1997
4
cm-1 (s, CO). Elemental analysis calcd for C57H50BF24OP2Rh: C,
49.52; H, 6.64. Found: C, 49.23; H, 6.52. Data for 11a′: 31P{1H}
NMR (CD2Cl2; δ, ppm): 35.52 (dd left part of an AX system, J )
248.2 Hz, J ) 104.5 Hz), 16.86 (dd right part of an AX system, J
1
) 248.2 Hz, J ) 103.8 Hz). H NMR (δ, ppm): 8.14 (d, J ) 7.8
Preparation of [(C10H5(CH2P(iPr2)2)Rh(H)(CO)2][BF4] (13a).
A young NMR tube containing 25 mg (0.041 mmol) of [(C10H5-
(CH2P(iPr2)2)(H)Rh(CO)][BF4] dissolved in 0.7 mL of CDCl3 was
charged with CO gas (1.5 atm). The orange solution turned to bright
yellow immediately, exclusively yielding complex 13a.
Hz, 1H, Ar), 7.80 (d, J ) 7.8 Hz, 1H, Ar), 7.76 (s, 1H, Ar), 7.67
(m, 2H, Ar), 3.90 (d, 1H, J ) 10.8 Hz, ArHRh), 3.74 (m, 3H,
overlapping signals of CH2P), 3.39 (vtd, 1H, J ) 12.0 Hz, J ) 3.9
Hz, CH2P), 2.42 (m, 4H, PCH(CH3)2), 1.35 (m, 12H, PCH(CH3)2),
1.11 (m, 12H, PCH(CH3)2). 13C{1H} NMR (δ, ppm): 183.89 (dt, J
) 90.5 Hz, J ) 12.1 Hz, CO), 155.69 (s, Ar), 144.10 (s, Ar), 141.82
(s, Ar), 138.81 (s, Ar), 130.97 (s, Ar), 129.32 (s, Ar), 128.41 (d, J
) 7.8 Hz, Ar), 127.59 (d, J ) 20.4 Hz, Ar), 124.42 (s, Ar), 109.94
(s, Ar), 31.99 (d, J ) 16.5 Hz, CH2P), 31.02 (d, J ) 16.5 Hz,
CH2P), 26.39 (dd, J ) 23.8 Hz, J ) 2.0 Hz, PCH(CH3)2), 24.72
(dd, J ) 24.1 Hz, J ) 2.1 Hz, PCH(CH3)2), 19.15 (m, PCH(CH3)2),
18.68 (m, PCH(CH3)2). 19F{1H} NMR (δ, ppm): -152.64 (s, BF4).
IR (film; cm-1) ν 1997 cm-1 (s, CO). Elemental analysis calcd for
C25H38BF4OP2Rh: C, 49.53; H, 6.32. Found: C, 49.46; H, 6.28.
1
31P{1H} NMR (CDCl3; δ, ppm, -50 °C): 79.54 (dd, JRhP
)
2
1
92.8 Hz, JPP ) 51.9 Hz). H NMR (δ, ppm, -50 °C): 7.83 (d, J
) 5.1 Hz, 1H, Ar), 7.68 (d, J ) 5.1 Hz, 1H, Ar), 7.67 (s, 1H, Ar),
7.44 (m, 2H, Ar), 3.93 (vt, J ) 5.3 Hz, 1H, CH2P), 3.91 (vt, J )
5.2 Hz, 1H, CH2P), 3.70 (vt, J ) 5.5 Hz, 2H, CH2P), 2.63 (m, 4H,
PCH(CH3)2), 1.39 (m, 12H, PCH(CH3)2), 1.07 (m, 12H,
PCH(CH3)2), -7.88 (broad s, 1H, RhH). 13C{1H} NMR (δ, ppm,
-50 °C): 184.43 (dvt, 1JRhP ) 40.7 Hz, JPC ) 6.8 Hz, CO), 183.87
(dvt, 1JRhP ) 42.1 Hz, JPC ) 7.1 Hz, CO), 146.42 (d, 1JRhC ) 22.5
Hz, Ar), 142.60 (d, 2JPC ) 7.5 Hz, Ar), 141.86 (d, J ) 7.1 Hz, Ar),
132.74 (s, Ar), 129.77 (s, Ar), 128.25 (s, Ar), 126.84 (s, Ar), 126.04
(s, Ar), 124.61 (s, Ar), 124.05 (vt, J ) 6.8 Hz, Ar), 36.97 (vt, J )
Preparation of [(C10H5(CH2P(tBu2)2)(H)Rh(CO)][X] (X )
BArF 11b, X ) BF4 11b′). To an etheral solution (5 mL) of 30
4
mg (0.052 mmol) of [(C10H5(CH2P(tBu2)2)Rh(CO)], an equimolar
2
amount of [H(Et2O)][BArF ] was added. A few minutes after the
15.8 Hz, CH2P), 34.68 (vt, J ) 15.4 Hz, CH2P), 27.78 (dvt, JRhP
4
) 40.7 Hz, JPP ) 12.2 Hz, PCH(CH3)2), 26.37 (dvt, J ) 12.5 Hz,
2JRhP ) 1.1 Hz, PCH(CH3)2), 19.29 (m, PCH(CH3)2), 18.44 (m,
PCH(CH3)2). 19F{1H} NMR (δ, ppm): -153.57 (s, BF4). IR (CHCl3;
cm-1) ν 2129 (m), 2120 (w), 2097 (s), 2085 (s). An elemental
analysis was not possible because of liberation of CO ligand under
reduced pressure.
Preparation of [(C10H5(CH2P(tBu2)2)Rh(H)(Cl)(CO)] (14b
and 14b′). Methylene chloride solutions (5 mL) of 30 mg of 2b
(0.045 mmol) were set under a CO atmosphere. After the solvent
was removed under reduced pressure, the residue was washed with
diethyl ether (3 × 5 mL) and dried under reduced pressure, affording
20.7 mg (0.034 mmol, 74%) of an isomeric mixture of 14b and
14b′ as bright yellow powder.
addition, the solvent was evaporated under reduced pressure. The
residue was washed with pentane (5 × 5 mL) and dried, affording
55.6 mg (0.039 mmol, 74%) of 10b. To an etheral solution (5 mL)
of 30 mg (0.052 mmol) of [(C10H5(CH2P(tBu2)2)Rh(CO)], an
equimolar amount of 57% HBF4 · Et2O was slowly added. During
the addition, a yellow powder precipitated. The solvent was
decanted, and the residue was washed with diethyl ether (2 × 10
mL) and dried under reduced pressure to afford 33.4 mg (0.050
mmol, 97%) of 11b′ as a bright yellow solid.
Data for 11b: 31P{1H} NMR (CD2Cl2; δ, ppm): 47.57 (dd left
part of an AX system, J ) 247.2 Hz, J ) 103.1 Hz), 30.89 (dd
right part of an AX system, J ) 247.2 Hz, J ) 99.6 Hz). 1H NMR
(δ, ppm): 8.18 (d, J ) 8.0 Hz, 1H, Ar), 7.93 (d, J ) 8.0 Hz, 1H,
Ar), 7.77 (m, 2H, Ar), 7.66 (s, 1H, Ar), 4.10 (broad t, J ) 12.2 Hz,
1H, CH2P), 3.87 (d, J ) 16.5 Hz, 1H, ArHRh), 3.64 (ddd, J )
36.7 Hz, J ) 20.1 Hz, J ) 8.0 Hz, 2H, CH2P), 3.44 (broad t, J )
12.1 Hz, 1H, CH2P), 1.57 (d, J ) 14.5 Hz, 9H, PC(CH3)3), 1.53
(d, J ) 14.5 Hz, 9H, PC(CH3)3), 1.27 (d, J ) 14.5 Hz, 18H,
PC(CH3)3). 13C{1H} NMR (δ, ppm): 188.62 (dt, J ) 91.3 Hz, J )
11.6 Hz, CO), 156.28 (s, Ar), 144.56 (s, Ar), 138.77 (s, Ar), 131.56
(s, Ar), 129.89 (s, Ar), 129.62 (d, J ) 8.0 Hz, Ar), 129.26 (s, Ar),
127.03 (d, J ) 19.4 Hz, Ar), 125.90 (s, Ar), 109.65 (s, Ar), 37.74
(dd, J ) 29.8 Hz, J ) 14.4 Hz, PC(CH3)3), 35.57 (dd, J ) 16.2
Hz, J ) 9.2 Hz, PC(CH3)3), 31.23 (d, J ) 17.7 Hz, CH2P), 29.90
(d, J ) 2.1 Hz, PC(CH3)3), 29.62 (d, J ) 3.2 Hz, PC(CH3)3), 29.20
(d, J ) 3.1 Hz, PC(CH3)3), 29.08 (d, J ) 3.4 Hz, PC(CH3)3) 26.35
Data for14b′: 31P{1H} NMR (CD2Cl2; δ, ppm): 95.21 (dd left
2
1
part of an AB system, JPP ) 315.4 Hz, JRhP ) 98.4 Hz), 94.15
(dd right part of an AB system, 2JPP ) 315.4 Hz, 1JRhP ) 98.4 Hz).
1H NMR (δ, ppm): 7.81 (d, J ) 8.1 Hz, 1H, Ar), 7.61 (d, J ) 8.1
Hz, 1H, Ar), 7.48 (s, 1H, Ar), 7.37 (m, 2H, Ar), 4.07 (dd, J ) 15.8
Hz, J ) 8.7 Hz, 1H, CH2P), 3.56 (m, 4H, overlapped with CH2P
signals of 14b), 3.09 (dd, J ) 10.3 Hz, J ) 5.7 Hz, 1H, CH2P),
1.41 (m, 18H, overlapped with PC(CH3)3 signals of 14b), 1.26 (m,
18H, overlapped with PC(CH3)3 signals of 14b), -15.32 (dt, 1H,
1
2JPH ) 9.2 Hz, JRhH ) 4.2 Hz). 13C{1H} NMR (δ, ppm): 193.81
1
(dt, J ) 43.9 Hz, J ) 9.5 Hz, CO), 169.75 (d, JRhC ) 25.9 Hz,
2
2
Cipso), 146.44 (dd, JPC ) 12.7 Hz, JRhC ) 3.2 Hz, Ar), 141.57
(dd, 2JPC ) 9.5 Hz, 2JRhC ) 5.1 Hz, Ar), 133.11 (s, Ar), 128.87 (s,
Ar), 128.43 (s, Ar), 126.92 (s, Ar), 125.13 (s, Ar), 124.94 (s, Ar),
121.02 (d, J ) 15.7 Hz, Ar), 38.09 (dvt, J ) 34.1 Hz, J ) 8.2 Hz,
(d, J ) 17.8 Hz, CH2P). 19F{1H} NMR (δ, ppm): -63.12 (s, BArF ).
4
IR (film; cm-1) ν 1987 cm-1 (s, CO). Elemental analysis calcd for

1908 Organometallics, Vol. 28, No. 6, 2009
Frech et al.
overlapping signals with PC(CH3)3 of 14b), 36.73 (m, overlapping
signals with PC(CH3)3 of 14b), 33.78 (d, J ) 21.3 Hz, CH2P), 29.76
(d, J ) 4.0 Hz, PC(CH3)3), 29.54 (d, J ) 3.9 Hz, PC(CH3)3), 29.14
(d, J ) 2.8 Hz, PC(CH3)3), 29.03 (d, J ) 3.8 Hz, PC(CH3)3), 28.52
(d, J ) 20.8 Hz, CH2P). IR (film; cm-1) ν 2033 cm-1 (s, CO).
Data for 14b: 31P{1H} NMR (CD2Cl2; δ, ppm): 86.74 (dd left part
diethyl ether (2 × 5 mL) and dried under reduced pressure, affording
20.2 mg (0.036 mmol, 96%) of 14a′ as bright yellow powder.
31P{1H} NMR (THF-d8; δ, ppm): 79.03 (dd (AB), 2JPP ) 320.4
1
2
1
Hz, JRhP ) 97.1 Hz), 78.44 (dd (AB), JPP ) 320.4 Hz, JRhP
)
1
97.1 Hz). H NMR (δ, ppm): 7.79 (d, J ) 7.9 Hz, 1H, Ar), 7.59
(d, J ) 7.9 Hz, 1H, Ar), 7.47 (s, 1H, Ar), 7.31 (m, 2H, Ar), 3.94
2
2
2
1
(dvt, 2H, JPH ) 8.0 Hz, CH2P), 3.53 (dvt, 2H, JPH ) 8.0 Hz,
CH2P), 2.92 (m, 2H, PCH(CH3)2), 2.35 (m, 2H, PCH(CH3)2), 1.29
of an AB system, JPP ) 328.8 Hz, JRhP ) 104.5 Hz), 86.44 (dd
2
1
right part of an AB system, JPP ) 328.8 Hz, JRhP ) 104.5 Hz).
1H NMR (δ, ppm): 7.78 (d, J ) 8.1 Hz, 1H, Ar), 7.70 (d, J ) 8.0
Hz, 1H, Ar), 7.34 (m, 2H, Ar), 7.25 (s, 1H, Ar), 3.97 (dd, J ) 15.6
Hz, J ) 8.7 Hz, 1H, CH2P), 3.56 (m, 4H, overlapped with CH2P
signals of 14b′), 2.98 (dd, J ) 10.5 Hz, J ) 7.1 Hz, 1H, CH2P),
1.41 (m, 18H, overlapped with PC(CH3)3 signals of 14b′), 1.26
(m, 18H, overlapped with PC(CH3)3 signals of 14b′), -7.67 (dt,
1H, 2JPH ) 8.6 Hz, 1JRhH ) 8.4 Hz). 13C{1H} NMR (δ, ppm): 188.62
2
1
(m, 24H, PCH(CH3)2), -14.89 (dt, 1H, JPH ) 27.0 Hz, JRhH
)
9.4 Hz). 13C{1H} NMR (δ, ppm): 189.78 (dt, J ) 41.2 Hz, J ) 9.3
1
2
Hz, CO), 169.13 (d, JRhC ) 26.1 Hz, Cipso), 145.23 (dd, JPC
12.5 Hz, JRhC ) 3.0 Hz, Ar), 141.31 (dd, JPC ) 9.2 Hz, JRhC
)
)
2
2
2
4.9 Hz, Ar), 133.41 (s, Ar), 129.02 (s, Ar), 128.29 (s, Ar), 126.43
(s, Ar), 125.01 (s, Ar), 124.87 (s, Ar), 121.31 (d, J ) 15.8 Hz, Ar),
37.77 (dvt, J ) 34.2 Hz, J ) 8.1 Hz), 36.58 (m), 33.63 (d, J )
21.1 Hz, CH2P), 29.49 (d, J ) 3.8 Hz, PC(CH3)3), 29.32 (d, J )
3.9 Hz, PC(CH3)3), 29.04 (d, J ) 2.7 Hz, PC(CH3)3), 28.94 (d, J
) 3.6 Hz, PC(CH3)3), 28.47 (d, J ) 20.9 Hz, CH2P). IR (film;
cm-1) ν 2041 cm-1 (s, CO). Elemental analysis calcd for
C25H38ClOP2Rh: C, 54.12; H, 6.90. Found: C, 54.44; H, 7.21.
1
(dt, J ) 45.2 Hz, J ) 5.7 Hz, CO), 155.97 (d, JRhC ) 29.9 Hz,
Cipso), 145.74 (dd, 2JPC ) 9.5 Hz, 2JRhC ) 5.7 Hz, Ar), 140.69 (dd,
2JPC ) 14.6 Hz, 2JRhC ) 3.2 Hz, Ar), 133.38 (s, Ar), 129.03 (s, Ar),
128.65 (s, Ar), 125.64 (s, Ar), 124.77 (s, Ar), 124.10 (s, Ar), 121.48
(d, J ) 12.8 Hz, Ar), 38.09 (dvt, J ) 34.1 Hz, J ) 8.2 Hz,
overlapping signals with PC(CH3)3 of 14b), 36.73 (m, overlapping
signals with PC(CH3)3 of 14b), 32.56 (d, J ) 21.3 Hz, CH2P), 29.94
(d, J ) 4.2 Hz, PC(CH3)3), 29.62 (d, J ) 3.8 Hz, PC(CH3)3), 29.20
(d, J ) 3.1 Hz, PC(CH3)3), 29.08 (d, J ) 3.6 Hz, PC(CH3)3), 28.76
(d, J ) 21.0 Hz, CH2P). IR (film; cm-1) ν 2062 cm-1 (s, CO).
Elemental analysis calcd for C29H46ClOP2Rh: C, 57.01; H, 7.59.
Found: C, 56.86; H, 7.34.
Acknowledgment. This work was supported by the Swiss
National Science Foundation (SNSF), the University of
Zurich, the Israel Science Foundation (ISF), the Minerva
Foundation, and the Helen and Martin Kimmel Center for
Molecular Design. D.M. is the holder of the Israel Matz
Professorial Chair of Organic Chemistry.
Preparation of [(C10H5(CH2P(iPr2)2)Rh(H)(Cl)(CO)] (14a′).
THF solutions (5 mL) of 20.0 mg (0.038 mmol) of [(C10H5-
(CH2P(iPr2)2)Rh(CO)] were treated with an equimolar amount of
hydrochloric acid (∼4.0 M in dioxane). After the solvent was
removed under reduced pressure, the residue was extracted with
Supporting Information Available: CIF file containing X-ray
crystallographic data for complex 3a. This material is available free
of charge via the Internet at http://pubs.acs.org.
OM801147W