New Group 9 metal complexes containing N,P-chelate ligand system.: Synthesis, characterization and application to catalytic hydrogenation

Article abstract of DOI:10.1016/S0022-328X(00)00607-0

New N,P-chelating o-carboranylaminophosphine ligand Cab^N,P 2 [Cab^N,P=o-C₂B₁₀H₁₀(CH ₂NMe₂)(PPh₂)-N,P] was prepared from o-carboranylamine LiCab^N [Cab^N=o-C₂B₁₀H₁₀(CH ₂NMe₂)-N] and chlorodiphenylphosphine. Consequently, the reaction of [M(cod)(solv)₂]⁺BF₄^- (M=Rh, Ir; cod=cycloocta-1,5-diene) with 2 was investigated. The resulting rhodium and iridium metal complexes [(Cab^N,P)M(cod)]⁺BF₄^- 3 (M=Rh 3a, Ir 3b) were characterized by NMR spectroscopy and elemental analysis. In addition, an X-ray structure analysis was performed on complex 3a, where the potential N,P-chelate ligand 2 was found to coordinate in a bidentate mode. The subsequent reaction of 3 with PPh₃ and CO resulted in the dissociation of the N,P-chelate ligand 2 to yield the penta-coordinate metal complexes [(PPh₃)₂M(CO)₃]⁺BF₄ ^- 4 (M=Rh 4a, Ir 4b). The structure of 4a was determined by X-ray diffraction analysis, exhibiting a trigonal bipyramidal configuration with the triphenylphosphine ligands occupying axial positions. The activities of complex 3 as a catalyst precursor during the hydrogenation of cyclohexene were tested and produced the cyclohexane with 100% conversion in the case of 3a.

Full text of DOI:10.1016/S0022-328X(00)00607-0

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Journal of Organometallic Chemistry 614–615 (2000) 83–91
New Group 9 metal complexes containing N,P-chelate
ligand system.
Synthesis, characterization and application to catalytic
hydrogenation
Heung-Sae Lee a, Jin-Young Bae a, Jaejung Ko a,*1, Yong Soo Kang b,
Hoon Sik Kim b,*2, Sung-Joon Kim a, Jang-Hoon Chung c, Sang Ook Kang a,*3
a Department of Chemistry, Korea Uni6ersity, 208 Seochang, Chochiwon, Chung-nam 339-700, South Korea
b Korea Institute of Science and Technology, Cheongryangri, Seoul 130-650, South Korea
c Department of Chemistry, Myongji Uni6ersity, Yongin, Kyunggido 449-728, South Korea
Received 28 January 2000
Dedicated to Professor Sheldon G. Shore on the occasion of his 70th birthday.
Abstract
New N,P-chelating o-carboranylaminophosphine ligand CabN,P 2 [CabN,P=o-C2B10H10(CH2NMe2)(PPh2)-N,P] was prepared
from o-carboranylamine LiCabN [CabN=o-C2B10H10(CH2NMe2)-N] and chlorodiphenylphosphine. Consequently, the reaction of
[M(cod)(solv)2]+BF4− (M=Rh, Ir; cod=cycloocta-1,5-diene) with 2 was investigated. The resulting rhodium and iridium metal
complexes [(CabN,P)M(cod)]+BF−4 3 (M=Rh 3a, Ir 3b) were characterized by NMR spectroscopy and elemental analysis. In
addition, an X-ray structure analysis was performed on complex 3a, where the potential N,P-chelate ligand 2 was found to
coordinate in a bidentate mode. The subsequent reaction of 3 with PPh3 and CO resulted in the dissociation of the N,P-chelate
ligand 2 to yield the penta-coordinate metal complexes [(PPh3)2M(CO)3]+BF4− 4 (M=Rh 4a, Ir 4b). The structure of 4a was
determined by X-ray diffraction analysis, exhibiting a trigonal bipyramidal configuration with the triphenylphosphine ligands
occupying axial positions. The activities of complex 3 as a catalyst precursor during the hydrogenation of cyclohexene were tested
and produced the cyclohexane with 100% conversion in the case of 3a. © 2000 Elsevier Science B.V. All rights reserved.
Keywords: Chelate; Rhodium; Iridium; o-Carborane; Catalyst precursor; Hydrogenation
1. Introduction
can generate a six-membered chelate ring by coordina-
tion through the nitrogen and phosphorus to a metal
center. In addition, phosphine ligands possessing an
o-carboranyl group deserve particular attention, and
influence of this group as a rigid ligand backbone [3] in
six-membered metal chelates on the hydrogenation has
been studied.
In recent years, transition metal complexes with lig-
ands containing dissimilar donor atoms such as phos-
phorous and nitrogen have been widely investigated,
primarily for their applications in important homoge-
neous catalytic processes [1]. Therefore, the design of
such ligand systems containing one functional group
strongly bound to a late transition metal and another
coordinatively labile has been of considerable interest
[2]. The N,P-chelate ligand 2 described in this work
having an ortho-substituent bearing an amino group
1* Corresponding author.
2* Corresponding author.
3* Corresponding author. Fax: +82-415-8675396; sangok@
tiger.korea.acr
0022-328X/00/$ - see front matter © 2000 Elsevier Science B.V. All rights reserved.
PII: S0022-328X(00)00607-0

84
H.-S. Lee et al. / Journal of Organometallic Chemistry 614–615 (2000) 83–91
The use of o-carborane as the ligand backbone is
2.2. X-ray diffraction structure of the N,P-chelate
ligand CabN,P
rare in catalytic reactions, while the nido-{C2B9} com-
plex has been proven to be a useful ancillary ligand for
catalytic hydrogenation reactions [4]. This ligand 2 is
chosen because it has an arylphosphine at one end to
stabilize the metal ion in a low oxidation state and a
weakly coordinating amine function at the other end
which will readily be substituted by an incoming p-ac-
ceptor ligand.
In order to investigate the influence of the N,P-
chelate ligand 2 on the catalyst behavior of the complex
in the hydrogenation reaction, we have synthesized and
characterized the rhodium and iridium complexes 3. In
particular, complex 3a was successfully applied as a
homogeneous catalyst for the hydrogenation of cyclo-
hexene and its catalytic activity is discussed.
2
The molecular structure and atom-labeling scheme
for complex 2 are shown in Fig. 1; whereas, selected
,
bond distances (A) and angles (°) are presented in Table
2. The observed conformation of 2 ligand in the solid
state is nearly ideal for a bidentate N,P-chelate ligand.
The phosphorous and nitrogen lone-pair vectors are
nearly parallel and approximately face each other in the
solid state. Two carbon atoms of two phenyl groups
and one carbon atom of the cage are bonded to a
phosphorus atom in a pyramidal arrangement. The
,
PꢀC bond lengths of 1.828(2)–1.887(2) A and CꢀPꢀC
angles of 100.6(1)–107.7(1)° are similar to those in
1-PPh2-2-MeꢀC2B10H10 [5]. The two carbon atoms of
the two methyl groups and one carbon atom of the
methylene unit are bonded to a nitrogen atom in a
pyramidal arrangement. The intercage boronꢀboron
2. Results and discussion
,
,
(1.77–1.79 A) and boronꢀcarbon (1.71–1.73 A) dis-
tances are normal, and the carbonꢀcarbon distance
between the only adjacent carbons, C(1)ꢀC(2) 1.689(3)
2.1. Preparation and characterization of CabN,P
2
The reaction of the o-carboranylamine HCabN 1 with
1.1 equivalent of BuLi followed by the addition of one
equivalent of chlorodiphenylphosphine in THF at low
temperature (Scheme 1) results in the formation of the
,
A, is also in the range previously observed in other
o-carborane cage systems [6].
2.3. Reactions of 2 with [M(cod)(sol6)2]+BF−4
(M=Rh, Ir; cod=cycloocta-1,5-diene)
corresponding o-carboranylaminophosphine CabN,P
2
in good yield (65%).
The N,P-chelate metal complexes 3a,b were prepared
by reactions between the cationic complexes
[M(cod)(solv)2]+BF4− and a slight excess of the corre-
sponding N,P-chelate ligand 2 (Scheme 2). Isolation of
the pure products, which ranged in color from yellow
to orange, was achieved by recrystallization. Typically,
the yields of 3a,b were on the order of 72–75%.
The pure form of complex 2 is a yellowish, off-white
powder which, although slightly hygroscopic, can be
handled safely in air. Complex 2 is readily soluble in
Et2O and THF and is somewhat less soluble in benzene
and toluene. The composition of the new complexes 2
has been unequivocally established by elemental analy-
1
sis. The H- and 13C-NMR data are in agreement with
The elemental analysis results show that the air–sta-
ble complexes 3a,b have compositions corresponding to
a 1:1 metal complex of the M(cod) fragment and o-car-
boranylaminophosphine 2. The 1H-NMR spectra of
3a,b show signals for the cyclooctadiene ligand at 2.18–
2.58 (methylene protons) and at 5.45–5.50 ppm
the proposed cage structure and confirm the presence of
phosphino and amino groups at the cage 1- and 2-posi-
tions, respectively. The H-NMR data contain phenyl
1
resonances (7.24–7.82 ppm) for the cage 1-position and
a methyl resonance (2.30 ppm) and a methylene reso-
nance (3.32 ppm) for the dimethylamino substituent.
The compound shows only a single 31P-NMR signal;
these and other NMR (1H, 11B, and 13C) spectroscopic
data are consistent with the described N,P-chelate
structure, which has been determined by X-ray crystal-
lographic studies. Table 1.
1
(olefinic protons). In the H- and 13C{1H}-NMR spec-
tra of 3, the NꢀMe resonances are shifted to low field
compared to the corresponding resonance in the free
ligand. This observation is strong evidence for MꢀN
coordination [7]. The complex 3a is characterized by
31P{1H}-NMR spectroscopy with a doublet at 52.63
ppm and JRh-P coupling constant of 166.5 Hz, typical
for [Rh(cod)(PR3)2]+ [8] or [Rh(cod)(P-N)]+ [9] com-
pounds. A detailed analysis of the spectroscopic data
(1H-NMR, 11B-NMR, 13C-NMR, and IR spectra)
showed that the N,P-chelate ligand 2 is coordinated to
the metal(I) ion through the nitrogen and phosphorous
atoms. In addition, the spectroscopic data of chelates
3a,b suggest
a fluxional process [10] within the
Scheme 1.
molecules. This fluxionality could be due to inversion at

H.-S. Lee et al. / Journal of Organometallic Chemistry 614–615 (2000) 83–91
85
Table 1
X-ray crystallographic data and processing parameters for compounds 2, 3a.CH2Cl2, and 4a.CH2Cl2
2
3a.CH2Cl2
4a.CH2Cl2
Formula
C17H28B10NP
385.47
Monoclinic
P21/n (no. 14)
4
C26H42B11Cl2F4NPRh
768.30
Monoclinic
P21/c (no. 14)
4
C40H30B11Cl2F4O3P2Rh
881.239
Monoclinic
P21/n (no. 14)
4
Formula weight
Crystal system
Space group
Z
Cell constants
,
a (A)
9.8428(4)
21.103(2)
11.7825(1)
112.863(6)
2255.1(2)
0.126
12.8745(7)
13.3315(6)
20.6958(1)
90.977(5)
3551.6(3)
0.718
17.0197(9)
13.921(1)
17.3040(9)
104.285(5)
3973.0(5)
0.614
,
b (A)
,
c (A)
ß (°)
3
,
V (A )
v (cm−1
)
Crystal size (mm)
0.30×0.50×0.55
1.135
808
0.30×0.40×0.45
1.437
1560
0.50×0.45×0.50
1.473
1692
Dcalc (g cm−3
F(000)
)
Radiation
Wavelength (A)
q Range (°)
h, k, l collected
Reflections measured
Unique reflections
Reflections used in refinement
[I\2|(I)]
Mo–Ka
0.7170
1.93–25.97
+12,+26,914
4697
Mo–Ka
0.7170
1.58–25.97
+15,+16,925
7144
Mo–Ka
0.7170
1.50–25.97
+20,+17,921
8074
,
4402
3121
6818
5093
7768
5857
Parameters
284
437
481
Data/parameter ratio
15.5
15.60
0.0555
0.1592
1.294
16.15
0.0708
0.2058
0.797
aR1
0.0492
0.1443
1.076
bwR2
Goodness-of-fit on F2
a R1=S ꢀꢀFoꢀ−ꢀFcꢀꢀ/S ꢀFoꢀ (based on reflections with Fo2\2|F2o).
b wR2=[S [w(F2o−Fc2)2]/S [w(Fo2)2]]1/2; w=1/[|2(Fo2)+(0.095P)2]; P=[max(F2o, 0)+2Fc2]/3 (also with Fo2\2|F2o).
the nitrogen atom and this would account for the
absence of a diastereotopic AB pattern for the NCH2
protons. The above spectral data suggest that the N,P-
chelates 3a,b have the structure shown in Scheme 2.
Confirmation of this structure came from a single-crys-
tal X-ray structure determination.
plexes containing cod ligands trans to P donor atoms
[12]. On the contrary, the average RhꢀC(cod) distance
,
trans to nitrogen is 2.138(5) A, which is comparable to
that in Rh(I) complexes with a trans N donor ligand
[12]. Thus, the RhꢀC(cod) distance trans to phospho-
2.4. X-ray diffraction structure of the N,P-chelate
metal complex 3a
The molecular structure of 3a is shown in Fig. 2, and
a listing of selected bond lengths and angles for 3a can
be found in Table 2. The crystal structure shows that
coordination around the rhodium atom is approxi-
mately square–planar. The carborane cage is biden-
tately coordinated through N and P atoms to the Rh(I)
ion, while the cod is h4-coordinated to the metal. The
molecular structure of 3a is similar to that of
[(cod)M(DIPOF)]+BF−4 (M=Rh [11], Ir [1])
(DIPOF=oxazolinylferrocenyldiphenylphosphine). The
RhꢀP and RhꢀN bond lengths are in the range usually
found in this family of complexes [12]. The average
RhꢀC(cod) distance trans to the phosphorous is
Fig. 1. Molecular structure of CabN,P 2. The thermal ellipsoids are
drawn at the 30% probability level.
,
2.256(5) A, which is a normal value for Rh(I) com-

86
H.-S. Lee et al. / Journal of Organometallic Chemistry 614–615 (2000) 83–91
Fig. 2. Molecular structure of [(CabN,P)Rh(cod)]+BF4− 3a.CH2Cl2. The thermal ellipsoids are drawn at the 30% probability level.
rous is longer than that trans to nitrogen. A higher
contribution by back-donation is found in the alkene
fragment of cod trans to nitrogen. The six-membered
RhꢀPꢀCꢀCꢀCꢀN ring is non-planar, with the dihedral
angles between the planes defined by [Rh(1), P(1), C(3),
N(1)] and [P(1), C(1), C(2), C(3)] being 52.8(2)° The
sum of the angles [361.2(2)°] around Rh formed by the
coordinated N and P atoms and the midpoints of the
double-bond carbon atoms of cod indicates the planar-
ity of the (N,P)Rh(diene) moiety. The bond lengths and
angles associated with cod and the coordinated o-car-
boranylaminophosphine 2 are normal with respect to
the other o-carboranyl substituted compounds [6].
reaction occurs with other low-valent metals [2,13]
(Scheme 3).
We attribute these results to a reaction sequence
whose first step involves MꢀN bond breaking to form
a
three-coordinate species. With two relatively
strong donor ligands, PPh3 and CO, MꢀP dissociation
is most likely, and thus, five-coordinate com-
plexes 4 are generated [14]. We have direct evidence
for MꢀL bond breaking (L=N or P donor); there-
fore, a sequence related to ours has been postulated
in [(cod)M(ODIPNAP)]+BF4− (M=Rh, Ir) (ODIP-
NAP=oxazolinyldiphenylphosphinobinaphthalene)
[1b].
2.5. Reaction of 3 with CO and PPh3
2.6. X-ray diffraction structure of 4a
The N,P-chelate metal complex 3 is of direct rele-
vance to homogeneous catalysis since the weakly coor-
dinated end of the chelate should undergo ready
displacement by incoming p-acceptor ligands. To un-
derstand the coordination behavior and reactivity of 3,
we have studied its reactivity toward p-acceptor lig-
ands. CO was bubbled, at r.t. and 1 atm through a
CH2Cl2 solution containing 3 and PPh3 (1:2). The
compound [(PPh3)2M(CO)3]+BF4−, 4 (M=Rh 4a, Ir
4b), was almost quantitatively formed. A structure in
which the phosphorus atoms of PPh3 are trans to each
other was assigned on the basis of the 31P{1H}-NMR
spectrum. However, to confirm this analysis, we deter-
mined the crystal structure of 4a. It has been shown
that a dimethylamino arm of a chelate coordinated to
rhodium(I) can readily be displaced by CO, and syn-
thetic and kinetic studies have shown that a similar
The molecular structure of 4a is shown in Fig. 3, and
a listing of selected bond lengths and angles for 4a can
be found in Table 2. The crystal structure shows that
coordination around the rhodium atom is approxi-
mately trigonal-bipyramidal. The [Rh(CO)3(PPh3)2]+
cation is associated with the mutually trans RhꢀP dis-
tances Rh(1)ꢀP(1)=2.352(2) and Rh(1)ꢀP(2)=2.356(2)
,
A, with an interligand angle of of P(1)ꢀRh(1)ꢀP(2)=
177.53(6)°. The equatorial carbonyl ligands have
RhꢀCO linkages defined by Rh(1)ꢀC(1)=1.939(8),
,
Rh(1)ꢀC(2)=1.949(8), and Rh(1)ꢀC(3)=1.972(8) A.
The RhꢀCꢀO systems are close to linear (178.0(9)–
,
178.2(8)°) with a CꢀO distance of 1.11(1)–1.12(1) A.
Angles between the equatorial ligands show some devi-
ation from D3h symmetry with C(1)ꢀRh(1)ꢀC(3)=
116.6(4)° as compared to C(1)ꢀRh(1)ꢀC(2)=120.0(4)
and C(2)ꢀRh(1)ꢀC(3)=123.4(4)°. The axial–equatorial

H.-S. Lee et al. / Journal of Organometallic Chemistry 614–615 (2000) 83–91
87
Table 2
angles
are
close
to
90°,
ranging
from
.
,
Selected interatomic distances (A) and angles (°) in 2, 3a CH2Cl2, and
P(1)ꢀRh(1)ꢀC(2)=88.3(2) to P(1)ꢀRh(1)ꢀC(1)=91.1-
(2)°. The RhꢀPꢀC angles are all expanded from the
ideal tetrahedral value (range 112.5(2)–114.5(2)°) and
the C(ipso)ꢀPꢀC(ipso%) angles are all compressed (range
103.9(3)–106.0(3)°); PꢀC distances range from
4a.CH2Cl2
Bond Distances in 2
P(1)ꢀC(12)
P(1)ꢀC(1)
N(1)ꢀC(4)
C(1)ꢀC(2)
1.828(2)
1.887(2)
1.448(4)
1.689(3)
P(1)ꢀC(6)
N(1)ꢀC(3)
N(1)ꢀC(5)
1.832(2)
1.440(3)
1.464(4)
,
P(1)ꢀC(10)=1.813(7) to P(1)ꢀC(4)=1.820(7) A. It is
similar to that observed in the isoelectronic Ir(I) species
[Ir(CO)3(PPh3)2]+[HSO4]− 1/3H2O [15], in which the
average distances are IrꢀP=2.643(3) and IrꢀCO=
Bond Angles in 2
C(12)ꢀP(1)ꢀC(6) 103.3(1)
C(6)ꢀP(1)ꢀC(1) 100.6(1)
C(3)ꢀN(1)ꢀC(5) 110.1(2)
C(2)ꢀC(1)ꢀP(1) 113.7(1)
C(3)ꢀC(2)ꢀC(1) 118.6(2)
C(12)ꢀP(1)ꢀC(1) 107.7(1)
C(3)ꢀN(1)ꢀC(4)
C(4)ꢀN(1)ꢀC(5)
B(4)ꢀC(1)ꢀP(1)
112.0(2)
109.6(3)
129.5(2)
,
1.93(1) A.
2.7. Catalytic hydrogenation of cyclohexene
Bond Distances in 3a.CH2Cl2
The results of the hydrogenation of cyclohexene cata-
lyzed by cationic rhodium(I) and iridium(I) complexes
containing the N,P-chelate ligand 2 are shown in Table
3. The presence of the N,P-chelate ligand in the rhodi-
um(I) catalyst allows good catalytic activity during the
hydrogenation of cyclohexene (Scheme 4).
Rh(1)ꢀC(7)
Rh(1)ꢀC(11)
Rh(1)ꢀN(1)
P(1)ꢀC(20)
P(1)ꢀC(1)
N(1)ꢀC(4)
C(1)ꢀC(2)
C(6)ꢀC(7)
C(7)ꢀC(8)
C(9)ꢀC(10)
C(11)ꢀC(12)
2.119(5)
2.232(5)
2.300(4)
1.801(6)
1.892(5)
1.484(7)
1.676(7)
1.408(8)
1.503(8)
1.500(8)
1.499(8)
Rh(1)ꢀC(6)
Rh(1)ꢀC(10)
Rh(1)ꢀP(1)
P(1)ꢀC(14)
N(1)ꢀC(3)
N(1)ꢀC(5)
C(2)ꢀC(3)
C(6)ꢀC(13)
C(8)ꢀC(9)
C(10)ꢀC(11)
C(12)ꢀC(13)
2.156(5)
2.280(5)
2.306(3)
1.827(5)
1.480(7)
1.498(7)
1.521(8)
1.520(8)
1.518(9)
1.395(8)
1.516(9)
The yield of the catalytic hydrogenation was largely
dependent upon the reaction solvents. With the rhodi-
um(I) complex 3a, the yield was increased in a polar
methanol solvent. Thus, the hydrogenation of cyclohex-
ene with the catalyst precursor 3a proceeds with 100%
conversion operating at 20 atm (H2) and 80°C for 50
min in methanol. On the contrary, employment of the
iridium complex 3b resulted in 52.8% yield under the
same conditions. However, a better yield was observed
with 3b in 1,2-dichloroethane (90.0% conversion at
80°C). Based on this result, CabN,P 2 was found to be a
useful ligand in the hydrogenation of cyclohexene.
Compound 2 is representative of a series of easily
accessible chelating ligand in which the two het-
eroatoms can be independently introduced in consecu-
tive synthetic steps. Such a preparation warrants great
flexibility, and the approach should allow fine tuning of
the ligands, with respect to both their steric and their
electronic properties. Work directed towards the exten-
sion of the different ligands and further applications in
catalytic reactions is in progress.
Bond Angles in 3a.CH2Cl2
C(7)ꢀRh(1)ꢀC(6) 38.4(2)
C(6)ꢀRh(1)ꢀC(11) 78.6(2)
C(6)ꢀRh(1)ꢀC(10) 86.0(2)
C(7)ꢀRh(1)ꢀN(1) 145.6(2)
C(11)ꢀRh(1)ꢀN(1) 95.8(2)
C(7)ꢀRh(1)ꢀP(1) 89.8(2)
C(11)ꢀRh(1)ꢀP(1) 156.7(2)
N(1)ꢀRh(1)ꢀP(1) 92.6(1)
C(20)ꢀP(1)ꢀC(1) 107.3(2)
C(1)ꢀP(1)ꢀRh(1) 109.3(2)
C(3)ꢀN(1)ꢀC(5) 103.5(4)
C(3)ꢀN(1)ꢀRh(1) 115.1(3)
C(3)ꢀC(2)ꢀC(1) 118.7(4)
C(7)ꢀRh(1)ꢀC(11) 95.4(2)
C(7)ꢀRh(1)ꢀC(10) 79.7(2)
C(11)ꢀRh(1)ꢀC(10) 36.0(2)
C(6)ꢀRh(1)ꢀN(1) 174.0(2)
C(10)ꢀRh(1)ꢀN(1) 90.8(2)
C(6)ꢀRh(1)ꢀP(1)
91.8(2)
C(10)ꢀRh(1)ꢀP(1) 165.7(2)
C(20)ꢀP(1)ꢀC(14) 104.6(2)
C(14)ꢀP(1)ꢀC(1) 101.9(2)
C(3)ꢀN(1)ꢀC(4)
C(4)ꢀN(1)ꢀC(5)
C(2)ꢀC(1)ꢀP(1)
N(1)ꢀC(3)ꢀC(2)
Rh(1)ꢀC(2)
Rh(1)ꢀP(1)
P(1)ꢀC(10)
P(1)ꢀC(4)
P(2)ꢀC(34)
O(1)ꢀC(1)
109.8(4)
107.6(5)
112.8(3)
119.1(5)
Rh(1)ꢀC(1)
Rh(1)ꢀC(3)
Rh(1)ꢀP(2)
P(1)ꢀC(16)
P(2)ꢀC(22)
P(2)ꢀC(28)
O(2)ꢀC(2)
1.939(8)
1.949(8)
1.972(8)
2.356(2)
1.817(7)
1.816(7)
1.818(7)
1.11(1)
2.352(2)
1.813(7)
1.820(7)
1.818(7)
1.12(1)
O(3)ꢀC(3)
1.11(1)
3. Experimental
Bond Angles in 4a.CH2Cl2
C(1)ꢀRh(1)ꢀC(2) 120.0(4)
C(2)ꢀRh(1)ꢀC(3) 123.4(4)
C(2)ꢀRh(1)ꢀP(1) 88.3(2)
C(1)ꢀRh(1)ꢀP(2) 90.6(2)
C(3)ꢀRh(1)ꢀP(2) 90.3(2)
C(10)ꢀP(1)ꢀC(16) 104.8(3)
C(16)ꢀP(1)ꢀC(4) 103.9(3)
C(16)ꢀP(1)ꢀRh(1) 114.4(2)
C(22)ꢀP(2)ꢀC(34) 105.6(3)
C(34)ꢀP(2)ꢀC(28) 106.0(3)
C(34)ꢀP(2)ꢀRh(1) 114.5(2)
O(1)ꢀC(1)ꢀRh(1) 178.2(8)
O(3)ꢀC(3)ꢀRh(1) 178.2(8)
C(1)ꢀRh(1)ꢀC(3) 116.6(4)
C(1)ꢀRh(1)ꢀP(1)
C(3)ꢀRh(1)ꢀP(1)
C(2)ꢀRh(1)ꢀP(2)
91.1(2)
90.6(2)
89.3(2)
3.1. General considerations
All manipulations were performed under a dry, oxy-
gen-free, nitrogen or argon atmosphere using standard
Schlenk techniques or in a Vacuum Atmosphere HE-
493 dry box. THF was freshly distilled over potassium
benzophenone. Ether and toluene were dried and dis-
tilled from sodium benzophenone. Dichloromethane
and hexane were dried and distilled over CaH2. 11B-,
P(1)ꢀRh(1)ꢀP(2) 177.53(6)
C(10)ꢀP(1)ꢀC(4) 105.8(3)
C(10)ꢀP(1)ꢀRh(1) 114.3(2)
C(4)ꢀP(1)ꢀRh(1) 112.6(2)
C(22)ꢀP(2)ꢀC(28) 103.9(3)
C(22)ꢀP(2)ꢀRh(1) 112.5(2)
C(28)ꢀP(2)ꢀRh(1) 113.3(2)
O(2)ꢀC(2)ꢀRh(1) 178.0(9)
1
13C-, H-, and 31P-NMR spectra were recorded on a
Varian Gemini 2000 spectrometer operating at 64.2,

88
H.-S. Lee et al. / Journal of Organometallic Chemistry 614–615 (2000) 83–91
50.3, 200.1, and 80.0 MHz, respectively. All boron-11
chemical shifts were referenced to BF.3Et2O (0.0 ppm)
with a negative sign indicating an upfield shift. All
proton and carbon chemical shifts were measured rela-
tive to internal residual chloroform from the lock sol-
vent (99.5% CDCl3) and then referenced to Me4Si (0.00
ppm). The 31P-NMR spectra were recorded with 85%
H3PO4 as an external standard. IR spectra were
recorded on a Biorad FTS-165 spectrophotometer. Ele-
mental analyses were performed with a Carlo Erba
Instruments CHNS-O EA1108 analyzer. All the melting
points recorded are uncorrected. Decaborane and 1-
dimethylaminoprop-2-yne were purchased from the
Callery Chemical Co. and Aldrich, respectively, and
were used without purification. The following starting
materials were prepared according to literature proce-
dures: HCabN 1 [16], [Rh(m-Cl)(cod)]2 [17], and [Ir(m-
Cl)(cod)]2 [18].
3.2. Synthesis of CabN,P
2
A solution of HCabN 1 (0.60g, 3.0 mmol) in THF (30
ml) was treated with 1.6 M hexane solution of BunLi (2
ml, 3.2 mmol) at −78°C. After stirring at −78°C for
2
h, the reaction mixture was treated with
chlorodiphenylphosphine (0.66 g, 3.0 mmol), warmed
to r.t., and then stirred for a further 12 h to complete
the reaction. The solvent was removed under reduced
pressure, and the residue was extracted with a small
amount of methylene chloride. The extract was loaded
on a silica gel column and eluted with a mixture of
hexane and benzene (2:3). The colorless band first
eluted was collected, and the solvents were removed in
vacuo to give 2 as a white powder (0.75 g, 1.94 mmol,
65%). 11B-NMR (64.2 MHz, ppm, C6D6); −1.26 (d,
1B, JBH=190 Hz), −4.58 (d, 1B, JBH=160 Hz), −
1
10.43 (d, 8B, JBH=110 Hz). H-NMR (200.13 MHz,
Scheme 2.
ppm, C6D6) 7.82 (m, 4H, PPH), 7.45 (m, 4H, PPH),
7.24 (m, 2H, PPH), 3.32 (d, 2H, CH2, 2.60 Hz), 2.30 (s,
6H, NMe); 13C-NMR (50.3 MHz, ppm, CDCl3) 135.31
(PPH), 131.42 (PPH), 128.65 (PPH), 62.83 (s, 1C, CH2),
46.2 (s, 2C, NMe). 31P{1H}-NMR (80.0 MHz, ppm,
C6D6): −19.36 (s, PPh2). Anal. Calc. for C17H28B10NP:
C, 52.97; H, 7.32; N, 3.63. Found: C, 53.01; H, 7.36; N,
3.59%. Rf=0.96 by silica gel TLC analysis (benzene),
m.p.=114°C. IR spectrum (KBr pellet, cm−1) 3070
(w), 3055 (w), 2955 (w), 2930 (w), 2820 (w), 2649 (w),
2610 (s), 2590 (s), 2555 (s), 2550 (s), 1475 (m), 1465 (m),
1449 (m), 1435 (s), 1376 (w), 1304 (w), 1264 (w), 1157
(w), 1092 (m), 1071 (m), 1049 (w), 1027 (m), 1000 (w),
862 (m), 748 (s), 741 (s), 697 (s), 542 (w), 499 (s).
Scheme 3.
3.3. Synthesis of 3a
To a solution of [Rh(cod)Cl]2 (0.12 g, 0.24 mmol) in
THF (5 ml) was added AgBF4 (0.10 g, 0.51 mmol). The
immediate formation of AgCl occurred as indicated by
a white precipitate. The reaction mixture was stirred
vigorously for 1 h. The cloudy gray reaction mixture
was filtered through a fine frit with Celite to give a
yellow filtrate. The N,P-chelate ligand 2 (0.20 g, 0.52
mmol) was then added, and the resulting solution was
magnetically stirred at r.t. for 1 h. When diethyl ether
(10 ml) was added to the solution, 3a precipitated as an
orange solid, which was collected by filtration and dried
under vacuum: 0.25 g (0.37 mmol), 75% isolated yield.
11B-NMR (64.2 MHz, ppm, CDCl3); −1.65 (s, 1B,
BF4), −4.73 (d, 2B, JBH=150 Hz), −7.88 (d, 4B,
Fig. 3. Molecular structure of [(PPh3)2Rh(CO)3]+BF4− 4a.CH2Cl2.
The thermal ellipsoids are drawn at the 30% probability level.
J
BH=160 Hz), −10.39 (d, 4B, JBH=160 Hz). 1H-

H.-S. Lee et al. / Journal of Organometallic Chemistry 614–615 (2000) 83–91
89
Table 3
Catalytic hydrogenation of cyclohexene a
Entry
Catalyst
Solvent
Reaction Time (min)
% Conversion
Product
1
2
3
4
5
6
7
8
9
3a
3b
Methanol
Methanol
Methanol
1,2ꢀDichloro ethane
1,2ꢀDichloro ethane
1,2ꢀDichloro ethane
Toluene
Toluene
Toluene
50
50
50
50
50
50
50
50
50
100.0
52.8
59.2
98.8
90.0
87.4
84.7
17.4
98.1
Cyclohexane
Cyclohexane
Cyclohexane
Cyclohexane
Cyclohexane
Cyclohexane
Cyclohexane
Cyclohexane
Cyclohexane
Willkinson’s catalyst
3a
3b
Willkinson’s catalyst
3a
3b
Willkinson’s catalyst
a Experimental conditions: 80°C; 300 psi (H2); [Cyclohexene]/[Catalyst]=1219.
NMR (200.13 MHz, ppm, CDCl3) 7.96 (m, 4H, PPH),
7.71 (m, 6H, PPH), 5.50 (br s, 4H=CH cod), 3.08 (d,
2H, NꢀCH2, 2.60 Hz), 2.88 (s, 6H, NMe), 2.54 (br s,
4H, CHexo cod), 2.18 (br s, 4H, CHendo cod). 13C{1H}-
NMR (50.3 MHz, ppm, CDCl3) 137.83 (PPH), 135.05
(PPH), 131.82 (PPH), 67.22 (s=CH cod), 60.46 (s,
NꢀCH2), 55.02 (s, NMe), 17.42 (s, CH2 cod). 31P{1H}-
NMR (80.0 MHz, ppm, CDCl3): 52.63 (s, PPh2,
52.63 (s, PPh2). Anal. Calc. for C25H40B11F4NPIr: C,
38.86; H, 5.22; N, 1.81. Found: C, 38.89; H, 5.25; N,
1.84%. Mp=185–188°C (dec.). IR spectrum (KBr pel-
let, cm−1) 2954 (m), 2924 (m), 2854 (m), 2568 (s), 2360
(m), 2340 (w), 1480 (w, sh), 1468 (s), 1436 (m), 1376
(m), 1312 (w), 1189 (w), 1053 (m, br), 884 (w), 745 (w),
700 (m), 670 (w), 517 (m).
JRhꢀP=166.5 Hz); Anal. Calc. for C25H40B11F4NPRh:
3.5. Reaction of 3a with PPh3 and CO
C, 43.94; H, 5.90; N, 2.05. Found: C, 43.96; H, 5.94; N,
2.08%. Mp=190–192°C (dec.). IR spectrum (KBr pel-
let, cm−1) 3063 (w), 2970 (w), 2879 (w), 2657 (w, sh),
2613 (s, sh), 2575 (s), 1478 (m), 1436 (s), 1415(w), 1318
(w), 1183 (w), 1089 (s), 1054 (vs), 1037 (s), 998 (m), 853
(w), 788 (w), 739 (m), 698 (m), 519 (w), 504 (s).
A solution of complex 3a (0.14 g, 0.2 mmol) in
toluene (10 ml) was treated with PPh3 (0.16 g, 0.6
mmol) at r.t. for 5 min. The orange color of the
solution quickly faded to give a brown–yellow solution.
This was placed under an atmosphere of CO causing a
color change to yellow. The NMR spectra of this
3.4. Synthesis of [(CabN,P)Ir(cod)]+BF−4 3b
sample
showed
complete
conversion
to
[(PPh3)2Rh(CO)3]+BF4− 4a. The volatile substances
were then removed in vacuo, and the resulting solid was
extracted with CH2Cl2. The addition of hexane to the
concentrated extract gave complex 4a as yellow crys-
tals. Yield: 0.14 g (0.18 mmol, 90%). 11B-NMR (64.2
A similar procedure was employed as described
above but with the following quantities: [Ir(cod)Cl]2
(0.17 g, 0.25 mmol); AgBF4 (0.10 g, 0.51 mmol); 2 (0.20
g, 0.52 mmol). An orange solid of 3b was isolated as
described for the rhodium complex 3a: 0.28 g (0.36
mmol), 72% isolated yield. 11B-NMR (64.2 MHz, ppm,
CDCl3); −1.72 (s, 1B, BF4), −5.43 (d, 2B, JBH=140
1
MHz, ppm, CDCl3); −2.23 (s, BF4). H-NMR (200.13
MHz, ppm, CDCl3) 7.64 (m, 4H, PPH), 7.58 (m, 6H,
PPH). 13C{1H}-NMR (50.3 MHz, ppm, CDCl3) 188.87
1
2
Hz), −8.20 (d, 4B, JBH=150 Hz), −11.21 (d, 4B,
(dt, RhꢀCO, JRhꢀC=80.6 Hz, JPꢀC=14.4 Hz), 135.44
1
J
BH=150 Hz). H-NMR (200.13 MHz, ppm, CDCl3)
(PPH), 132.77 (PPH), 128.74 (PPH). 31P{1H}-NMR
7.83 (m, 4H, PPH), 7.75 (m, 6H, PPH), 5.45 (br s,
4H=CH cod), 3.13 (d, 2H, NꢀCH2, 2.60 Hz), 2.93 (s,
6H, NMe), 2.58 (br s, 4H, CHexo cod), 2.34 (br s, 4H,
CHendo cod). 13C{1H}-NMR (50.3 MHz, ppm, CDCl3)
139.64 (PPH), 138.33 (PPH), 133.42 (PPH), 69.52 (s=
CH cod), 55.27 (s, NꢀCH2), 55.64 (s, NMe), 17.89 (s,
CH2 cod); 31P{1H}-NMR (80.0 MHz, ppm, CDCl3):
(80.0 MHz, ppm, CDCl3): 21.83 (dm, PPh2, JRhꢀP=
102.7 Hz). Anal. Calc. for C39H30BF4O3P2Rh: C, 58.68;
H, 3.79. Found: C, 58.66; H, 3.77%. M.p.=154–156°C
(dec.). IR spectrum (KBr pellet, cm−1) 3066 (w), 2076
(s), 2025 (s), 1998 (s), 1460 (m), 1420 (s), 1220 (w), 1086
(s), 1054 (s), 1028 (s), 998 (m), 838 (w), 764 (w), 734
(m), 650 (m), 536 (w), 488 (s).
3.6. Reaction of 3b with PPh3 and CO
A similar procedure was employed as described
above but with the following quantities: 3b (0.16 g, 0.21
mmol); PPh3 (0.16 g, 0.6 mmol). A yellow solid of
[(PPh3)2Ir(CO)3]+BF4− 4b was isolated as described for
Scheme 4.

90
H.-S. Lee et al. / Journal of Organometallic Chemistry 614–615 (2000) 83–91
the rhodium complex 4a: 0.17 g (0.19 mmol), 93%
1223-336033; e-mail: deposit@ccdc.cam.ac.uk or
www:http://www.ccdc.cam.ac.uk).
isolated yield. 11B-NMR (64.2 MHz, ppm, CDCl3);
1
−1.98 (s, BF4). H-NMR (200.13 MHz, ppm, CDCl3)
7.77 (m, 4H, PPH), 7.62 (m, 6H, PPH). 13C{1H}-NMR
2
(50.3 MHz, ppm, CDCl3) 172.8 (t, IrꢀCO, JPꢀC=9.4
Acknowledgements
Hz), 133.99 (PPH), 132.77 (PPH), 129.02 (PPH).
31P{1H}-NMR (80.0 MHz, ppm, CDCl3): 33.74 (PPh2).
Anal. Calc. for C39H30BF4IrO3P2: C, 52.77; H, 3.41.
Found: C, 52.74; H, 3.47%. Mp=163–165°C (dec.). IR
spectrum (KBr pellet, cm−1) 3062 (w), 2074 (s), 2020
(s), 2000 (s), 1473 (m), 1422 (s), 1410(w), 1323 (w), 1218
(w), 1086 (s), 1050 (s), 1025 (s), 1000 (m), 840 (w), 760
(w), 740 (m), 623 (m), 520 (w), 500 (s).
Financial support by the BK-21 program from the
Korean Ministry of Education is gratefully appreciated.
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