Specific complexation modes of tripodal polyphosphorus ligands with rhodium: Generating multimetallic compounds of controlled structure via simple ordination chemistry

Article abstract of DOI:10.1021/om020098l

Synthesis of structure-controlled organometallic complexes based on the chemistry of polyphosphorus ligands with rhodium was carried out. An evaluation of ligands activity in catalytic hydrogenation of olefins was also performed. It was observed that reac

Full text of DOI:10.1021/om020098l

3860
Organometallics 2002, 21, 3860-3866
Sp ecific Com p lexa tion Mod es of Tr ip od a l
P olyp h osp h or u s Liga n d s w ith Rh od iu m : Gen er a tin g
Mu ltim eta llic Com p ou n d s of Con tr olled Str u ctu r e via
Sim p le Coor d in a tion Ch em istr y
M. Brad Peori and Ashok K. Kakkar*
Department of Chemistry, McGill University, 801 Sherbrooke Street
West, Montreal, Quebec H3A 2K6, Canada
Received February 8, 2002
Synthesis of structure-controlled organometallic complexes based on the chemistry of
polyphosphorus ligands OdP[O(CH2)3PPh2]3 (1), PhP[O(CH2)3PPh2]2 (2), P[O(CH2)3PPh2]3
(3), P[O(CH2)10PPh2]3 (12), and PhP[O(CH2)10PPh2]2 (13), with [(µ-Cl)(1,5-C8H12)Rh]2, in which
1, 12, and 13 carry out a typical bridge-splitting reaction of peripheral phosphines with the
Rh-dimer, while 2 and 3 complex with rhodium through bridgehead phosphite and two
terminal phosphines leading to replacement of the 1,5-cyclooctadiene ligand also, is reported.
In tr od u ction
specific organic transformations. Thus, the effect of
overall structure of the metallodendrimer on the cata-
lytic activity and selectivity is an important and sig-
nificant issue. Phosphorus-based ligands are commonly
used in the design of homogeneous catalysts, especially
those containing rhodium,7 and macromolecular systems
incorporating such donor sites throughout the back-
bone8,9 are pivotal in heterogenizing homogeneous
catalysts. We were intrigued by the possibility of
constructing multimetallic complexes using tripodal
polyphosphorus ligands in which the choice of the ligand
at the core and in the repeating units will dictate the
emerging structure and may provide an understanding
of how the final dendritic structure influences the
activity of transition metal centers in these dendrimers.
We report herein a simple synthetic route to a variety
of such ligands and examine their way of complexation
with rhodium that leads to a controlled construction of
multinuclear organometallic complexes in a divergent
manner. An evaluation of their activity in catalytic
hydrogenation of olefins is also presented.
Metallodendrimers constitute a relatively new and
promising class of highly branched macromolecules
possessing a well-defined and functionalized framework
that imparts novel and unusual properties.1 Synthesis
of such macromolecular transition metal complexes of
controlled architecture is a fascinating area of research
due to its potential in the development of active,
selective, and recoverable catalysts. Catalytic dendrim-
ers that have been investigated in this regard consist
of transition metal centers placed at their core or along
the periphery.2 Many of the latter systems show a
decrease in catalytic activity with an increase of surface
congestion, brought on by the extensive branching of
the dendritic structure.3 In core-functionalized dendrim-
ers, crowding around the metal center reduces acces-
sibility of the substrate to the catalytic site.4 Placing
active transition metal centers throughout the backbone
is proving to be a beneficial approach in developing
efficient catalysts, since it increases the number of
available active transition metal sites per dendrimer.5
Metal centers placed within the structure of dendrimers
also offer new topologies6 that might alter reaction
mechanisms and provide new pathways for affecting
Resu lts a n d Discu ssion
Polyphosphorus ligands OdP[O(CH2)3PPh2]3 (1), PhP-
[O(CH2)3PPh2]2 (2), and P[O(CH2)3PPh2]3 (3) were syn-
thesized by reacting the appropriate phosphorus chlo-
* Corresponding author. E-mail: ashok.kakkar@mcgill.ca.
(1) (a) Oosterom, G. E.; Reek, J . N. H.; Kamer P. C. J .; van Leeuwen,
P. W. N. M. Angew. Chem., Int. Ed. 2001, 40, 1828. (b) Majoral, J .-P.;
Caminade, A.-M. Chem. Rev. 1999, 99, 845. (c) Cuadrado, I.; Moran,
M.; Casado, C. M.; Alonso, B.; Losada, J . Coord. Chem. Rev. 1999, 193-
195, 395.
(2) (a) Togni, A.; Bieler, N.; Burckhardt, V.; Kollner, C.; Pioda, G.;
Schnieder, R.; Schnyder, A. Pure Appl. Chem. 1999, 71, 1531. (b) De
Groot, D.; Eggeling, E. B.; de Wilde, J . C.; Kooijman, H.; van Haaren,
R. J .; van der Made, A. W.; Spek, A. L.; Vogt, D.; Reek, J . N. H.;
Kramer, P. C. J .; Leeuwen, P. W. N. M. Chem. Commun. 1999, 1623.
(c) Knapen, J . W. S.; van der Made, A. W.; de Wilde, J . C.; van
Leeuwen, P. W. N. M.; Wijkens, P.; Grove, D. M.; van Koten, G. Nature
1994, 372, 659.
(6) (a) Achar, S.; Puddephatt, R. J . Organometallics 1996, 15, 43.
(b) Achar, S.; Puddephatt, R. J . Angew. Chem., Int. Ed. Engl. 1994,
33, 847.
(7) Iwasawa, Y. Tailored Metal Catalysts; D. Reidel Publ.: Dor-
drecht, The Netherlands, 1986.
(8) (a) Kakkar, A. Chem. Rev. 2002, in press. (b) Dasgupta, M.; Peori,
M. Brad; Kakkar, A. Coord. Chem. Rev. 2002, in press. (c) Petrucci,
M. G. L.; Kakkar, A. K. Chem. Mater. 1999, 11, 269. (d) Petrucci, M.
G. L.; Kakkar, A. K. Organometallics 1998, 17, 1798. (e) Petrucci, M.
G. L.; Kakkar, A. K. Adv. Mater. 1996, 8 (3), 251. (f) Petrucci, M. G.
L.; Kakkar, A. K. J . Chem. Soc., Chem. Commun. 1995, 1507. (g)
Petrucci, M. G. L.; Lebuis, A.-M.; Kakkar, A. K. Organometallics 1998,
17, 4966.
(3) Gorman, C. Adv. Mater. 1998, 10, 295.
(4) Newkome, G. R.; Yao, Z.; Baker, G. R.; Gupta, V. K.; Russo, P.
S.; Saunders, M. J . J . J . Am. Chem. Soc. 1986, 108, 849.
(5) Petrucci-Samija, M.; Guillemette, V.; Dasgupta, M.; Kakkar, A.
K. J . Am. Chem. Soc. 1999, 121, 1968.
(9) Beerens, H. I.; Wijkens, P.; J astrzebski, J . T. B. H.; Verpoort,
F.; Verdonck, L.; van Koten, G. J . Organomet. Chem. 2000, 603, 244.
10.1021/om020098l CCC: $22.00 © 2002 American Chemical Society
Publication on Web 08/20/2002

Tripodal Polyphosphorus Ligands with Rhodium
Organometallics, Vol. 21, No. 19, 2002 3861
Sch em e 1
Sch em e 2
P[O(CH2)3Cl]3 and PhP[O(CH2)3Cl]2, respectively. The
latter were then treated with KPPh2 in a THF suspen-
sion at 0 °C to give the desired products, P[O(CH2)3-
PPh2]3 and PhP[O(CH2)3PPh2]2. Although this second
route required fewer steps, the reaction with KPPh2
resulted in low yields, making the initial methodology
more attractive. Polyphosphorus ligand 1 contains
phosphorus oxide [P(V)] at the apical center that does
not bind transition metals. In contrast, ligands 2 and 3
contain phosphite at the apex and three phosphines on
the periphery, all four donor centers capable of coordi-
nating with transition metals. Ligands 1-3 showed two
peaks in their 31P{1H} NMR spectra (Table 1) that
corresponded with the bridgehead and peripheral phos-
phorus centers.
To prepare multimetallic complexes, polyphosphorus
ligand 1 was treated with 1.5 equiv of [(µ-Cl)(1,5-C8H12)-
Rh]2 in a bridge-splitting reaction.10 This involved the
addition of a solution of 1 to a concentrated solution of
the rhodium dimer in benzene, which ensured that the
rhodium dimer remained in excess, and yielded, as
expected, complex 4. The latter showed a doublet (δ
26.92 ppm, J Rh-P ) 149 Hz) for the terminal bound
phosphines and a singlet at δ 8.35 ppm for the unbound
P(V) center at the apex, in its 31P{1H} NMR spectrum.
It was then reacted with 3 equiv of ligand 2, leading to
complex 5, in which 1,5-cyclooctadiene (COD) ligand was
replaced with two phosphorus centers of ligand 2 (apical
phosphite and a terminal phosphine), leaving a free
phosphine ligand (Scheme 1).11 The 31P{1H} NMR
spectrum of 5 depicted an AMNX type of coupling
pattern at the rhodium center, leading to a doublet of
doublets of doublets (δ 188.39 ppm, J Rh-P ) 238 Hz and
J P-P ) 36 Hz) for the bridgehead P(III) phosphorus due
to its coupling with rhodium and two cis positioned
ride with HO-(CH2)3-PPh2 at 0 °C in the presence of
a strong base (NEt3) to remove HCl formed as a
byproduct, as NEt3‚HCl (Schemes 1 and 2). An alterna-
tive route to the synthesis of polyphosphorus ligands
involved the coupling of HO-(CH2)3Cl with PCl3 or
PhPCl2 at 0 °C in the presence of NEt3 to afford
(10) Hartley, F. R.; Murray, S. G.; Potter, D. M. J . Organomet. Chem.
1983, 254, 119.
(11) (a) Brown, T. H.; Green, P. J . J . Am. Chem. Soc. 1970, 92, 2359.
(b) Grim, S. O.; Satek, L. C. J . Coord. Chem. 1974, 3, 307. (c) Bianchini,
C.; Masi, D.; Meli, M.; Peruzzini, M.; Zanobini, F. J . Am. Chem. Soc.
1988, 110, 6411.

3862 Organometallics, Vol. 21, No. 19, 2002
Peori and Kakkar
Ta ble 1. 31P {1H} NMR Ch em ica l Sh ifts (109 MHz, C6D6, δ p p m ) a n d Cou p lin g Con sta n ts (Hz)a
PA
PA
PM
PM′
PA
compd
[OP(OR)3]
[P(OR)3]
[Chelating]
[Chelating]
[PhP(OR)2]
PN
other
1
2
3
4
s 8.39
s -14.79
s -15.96
s -16.04
d 26.92
J Rh-P ) 149
s -15.21
s 156.24
s 139.21
s 8.35
s 8.65
5
6
dd 12.39
ddd 188.39
J P-P ) 36
dd 23.74
J P-P ) 43
J Rh-P ) 151
J P-P ) 43
J Rh-P ) 129
dd 12.32
J P-P ) 44
J Rh-P ) 130
J Rh-P ) 238
ddd 187.42
J P-P ) 44
J Rh-P ) 236
7
ddd 160.48
J P-P ) 52
J Rh-P ) 278
ddd 160.48
J P-P ) 54
J Rh-P ) 278
ddd 161.93
J P-P ) 51
J Rh-P ) 278
ddd 161.03
J P-P ) 53
dd 14.03
d 26.56
J Rh-P ) 150
J P-P ) 52
J Rh-P ) 130
dd 13.94
J P-P ) 52
J Rh-P ) 129
dd 13.89
J P-P ) 51
J Rh-P ) 129
dd 14.13
J P-P ) 52
J Rh-P ) 131
dd 13.79
8
dd 12.31
ddd 187.44
J P-P ) 44
J Rh-P ) 237
ddd 159.41
J P-P ) 42
J Rh-P ) 278
ddd 188.23
J P-P ) 45
dd 26.56
s -16.13
J P-P ) 44
J Rh-P ) 130
dd 14.97
J P-P ) 42
J Rh-P ) 132
dd 12.57
J P-P ) 45
J Rh-P ) 128
dd 15.14
J P-P ) 43
J Rh-P ) 150
dd 26.25
J P-P ) 40
J Rh-P ) 140
dd 27.01
J P-P ) 44
J Rh-P ) 151
dd 25.79
9
s -15.97
10
11
d 24.37
J Rh-P ) 148
J Rh-P ) 278
ddd 162.32
J P-P ) 52
J Rh-P ) 237
ddd 160.04
J P-P ) 43
d 28.98
J Rh-P ) 149
J P-P ) 52
J Rh-P ) 130
J P-P ) 43
J Rh-P ) 131
J P-P ) 41
J Rh-P ) 140
J Rh-P ) 278
J Rh-P ) 278
a
PA refers to the bridgehead phosphorus and PM, PM′, and PN refer to bound peripheral phosphines: PM cis to P(OR)3 and PM′ cis to
PhP(OR)2, except for 9 and 11, where both PM and PM′ are cis to P(OR)3.
phosphine groups (Table 1). The two phosphines about
the chelated rhodium center showed two doublets of
doublets (δ 12.39 ppm, J Rh-P ) 129 Hz and J P-P ) 43
Hz; δ 23.74 ppm, J Rh-P ) 151 Hz and J P-P ) 43 Hz).
The spectrum was consistent with a square planar
arrangement of ligands at terminal rhodium centers.
The P(V) bridgehead phosphorus and the free phosphine
showed singlets at 8.65 and -15.21 ppm, respectively.
In a similar attempt to build multisite organometallic
complexes, ligand 2 was reacted with 1.5 equiv of [(µ-
Cl)(1,5-C8H12)Rh]2. A different reaction pattern of 2 led
to the formation of complex 6, in which, after successful
bridge-splitting reaction by the phosphite ligand, two
of the terminal phosphines wrapped around to replace
the chelating COD ligand (Scheme 1). This complex
showed an AM2X type of coupling pattern in its 31P-
{1H} NMR spectrum (Table 1) that was consistent with
a square planar arrangement of ligands around Rh. For
example, it showed a doublet of doublets of doublets at
δ 187.42 ppm (J Rh-P ) 236 Hz and J P-P ) 44 Hz) for
the bridgehead phosphite due to coupling with 103Rh and
two phosphines and a doublet of doublets (δ 12.32 ppm,
J Rh-P ) 130 Hz and J P-P ) 44 Hz) for the two trans
positioned phosphines bound to rhodium. Varying the
ratio and addition rates of the ligand to the rhodium
dimer did not result in any change and always led to
the formation of complex 6. The treatment of the latter
complex with excess PPh3 yielded no reaction, suggest-
ing that the polyphosphorus ligand was strongly che-
lated.
of the terminal phosphines. The remaining third ter-
minal phosphine then reacted with the rhodium dimer
in a simple bridge-splitting reaction. The arrangement
of the ligands at the metal center was deciphered from
its 31P{1H} NMR spectrum, which was, once again,
consistent with an AM2X type of coupling pattern. The
two terminal phosphines trans to each other in 7 showed
a doublet of doublets (δ 14.03 ppm, J Rh-P ) 130 Hz and
J P-P ) 52 Hz) due to coupling with 103Rh and the
bridgehead phosphite. The latter depicted a doublet of
doublets of doublets (δ 160.48 ppm, J Rh-P ) 278 Hz and
J P-P ) 52 Hz), due to coupling with 103Rh and two
phosphines. The nonchelated rhodium-bound phosphine
showed a doublet at δ 26.56 ppm (J Rh-P ) 150 Hz).
Lowering the ratio of the rhodium dimer to the poly-
phosphorus ligand 3 down to 0.5 equiv resulted in a
similar reaction pattern of bridge-splitting by the phos-
phite followed by replacement of the COD ligand by the
two terminal phosphines, leaving one free terminal
phosphine (δ -16.13 ppm). The latter could then be
reacted further with the rhodium dimer to give complex
7.
Complex 7 was reacted with 1 equiv of 2, which led
to the replacement of the 1,5-COD ligand with the
bridgehead phosphorus and one terminal phosphine,
yielding complex 8 with a free phosphine center. A
similar structural arrangement of ligands around Rh,
as described above for 5, 6, and 7, was ascertained from
their 31P{1H} NMR spectra. The bridgehead phosphorus
showed a doublet of doublets of doublets (δ 187.4 ppm,
J Rh-P ) 237 Hz and J P-P ) 44 Hz; δ 160.48 ppm, J Rh-P
) 278 Hz and J P-P ) 54 Hz), and the bound phosphines
showed a doublet of doublets each at δ 12.31 ppm, J Rh-P
) 130 Hz and J P-P ) 44 Hz; δ 13.94 ppm, J Rh-P ) 129
Hz and J P-P ) 52 Hz; δ 26.56 ppm, J Rh-P ) 150 Hz and
J P-P ) 43 Hz. The free terminal phosphine in 8 showed
a singlet at δ -16.13 ppm. The latter could then be
In a similar reaction, a solution of polyphosphorus
ligand 3 was added dropwise to a concentrated solution
of 2 equiv of the rhodium dimer in benzene at room
temperature. As mentioned above for the reaction of 2,
it led to the formation of complex 7, in which bridge-
splitting reaction by the phosphite was followed by
replacement of the 1,5-COD ligand via chelation by two

Tripodal Polyphosphorus Ligands with Rhodium
Organometallics, Vol. 21, No. 19, 2002 3863
Sch em e 3
Ta ble 2. 31P {1H} NMR Ch em ica l Sh ifts (109 MHz,
C6D6, δ p p m ) a n d Cou p lin g Con sta n ts (Hz)
reacted with 0.5 equiv of the Rh-dimer [(µ-Cl)(1,5-
C8H12)Rh]2 in benzene, leading to a successful bridge-
splitting reaction, as depicted by the appearance of a
doublet for the bound terminal phosphine (complex 10,
Table 1, δ 24.37 ppm, J Rh-P ) 148 Hz).
PA
PA
compd
[P(OR)3]
[PhP(OR)2]
PM
12
13
14
s 136.25
s -15.95
s -16.02
d 26.92
s 155.36
The reaction of complex 7 with 1 equiv of 3 led to the
formation of complex 9 via replacement of the bound
COD ligand in 7 with the chelating bridgehead phos-
phorus and one terminal phosphine of 3 and leaving two
free terminal phosphines. Complex 9 showed a doublet
of doublets of doublets for each bridgehead phosphorus
unit (δ 161.93 ppm, J Rh-P ) 278 Hz and J P-P ) 51 Hz;
δ 159.41 ppm, J Rh-P ) 278 Hz and J P-P ) 42 Hz), a
doublet of doublets for the trans positioned phosphines
on the first rhodium center (δ 13.89 ppm, J Rh-P ) 129
Hz and J P-P ) 51 Hz), and a doublet of doublets for the
bound phosphines on the second rhodium center (δ 26.25
ppm, J Rh-P ) 140 Hz and J P-P ) 40 Hz; δ 14.97 ppm,
J Rh-P ) 132 Hz and J P-P ) 42 Hz). The two free
phosphine centers showed a singlet at δ -15.97 ppm.
A solution of complex 9 was then added to a benzene
solution of 1 equiv of the rhodium dimer, leading to the
formation of complex 11 by a bridge-splitting reaction
of the terminal phosphines in 9 with [(µ-Cl)(1,5-C8H12)-
Rh]2. The formation of this complex was indicated by
the appearance of a doublet for the terminal (bound)
phosphines (δ 28.98 ppm, J Rh-P ) 149 Hz).
d 112.34
J Rh-P ) 253
J Rh-P ) 149
d 26.90
15
d 128.34
J Rh-P ) 247
J Rh-P ) 147
To test this hypothesis, the monophosphine reagent
HO-(CH2)10-PPh2 required for the synthesis of longer
alkane chain tripodal phosphines was prepared from
1-chloro-10-decanol by first protecting its hydroxyl group
by reacting it with Et2NSiMe3 in benzene to give Me3-
SiO-(CH2)10-Cl. The latter was reacted with KPPh2,
followed by deprotection with a methanol/citric acid
mixture, to give the monophosphine HO-(CH2)10-PPh2.
It was then reacted with PCl3 or PhPCl2 to give the
desired polyphosphorus ligands 12 and 13, respectively.
These ligands showed two peaks in their 31P{1H} NMR
spectra (Table 2) that were assigned to their bridgehead
and peripheral phosphorus centers. The polyphosphorus
ligand 12 was reacted with 2 equiv of the rhodium dimer
[(µ-Cl)(1,5-C8H12)Rh]2 in benzene. The bridge-splitting
reaction of the phosphorus center led to the exclusive
formation of complex 14 (Scheme 3). The 31P{1H} NMR
spectrum of the latter complex showed a doublet at δ
112.34 ppm for the bridgehead phosphite bound to
rhodium (J Rh-P ) 253 Hz) and a doublet for the three
terminal phosphines bound to rhodium at δ 26.92 ppm
(J Rh-P ) 149 Hz, Table 2). The lengthened arms of the
terminal phosphines placed the P(III) donor centers at
It was postulated that the reaction pattern of poly-
phosphorus ligands 2 and 3 may be due to the short
length of the alkane chain in HO-(CH2)3-PPh2 that
brings the terminal phosphines in close proximity to the
bridgehead phosphorus, leading to the formation of a
stable seven-membered chelate ring in these complexes.

3864 Organometallics, Vol. 21, No. 19, 2002
Peori and Kakkar
a sufficient distance that prevented their concerted
interaction with the bridgehead phosphorus to form a
chelating ring, to displace the bound COD ligand on
rhodium. A similar reaction of the tripodal ligand 13
with 1.5 equiv of [(µ-Cl)(1,5-C8H12)Rh]2 yielded complex
15 via a simple bridge-splitting reaction without any
chelating ring formation by the terminal phosphines
(Scheme 3, Table 2).
The results presented above suggest that the tripodal
phosphorus ligands play an important and useful role
in tailoring the structure of their corresponding orga-
nometallic complexes. For example, by starting with
ligand 1 at the core in which the apical phosphorus is
unable to carry out a bridge-splitting reaction with [(µ-
Cl)(1,5-C8H12)Rh]2, or with ligands 12 and 13, where the
length of the alkane chain arm prevents the formation
of a chelate ring, multimetallic complexes with a typical
spherical structure are obtained. In contrast, placing
polyphosphorus ligand 2 or 3 at the core or using them
as repeat units leads to nonspherical structures. Such
a structural control in the design of multimetallic
complexes such as organometallic dendrimers will be
extremely useful in tailoring their properties, leading
to efficient transition metal based catalysts.
tural arrangement of ligands around rhodium in the
resulting compounds are dependent on the type of
polyphosphorus ligand employed for the reaction. When
the central and terminal phosphorus units can act in
concert with each other, the chelate effect leads to
replacement of the COD ligand after a successful bridge-
splitting reaction by the apical phosphorus. The syn-
thetic elaboration of this methodology to construct
hyperbranched organometallic complexes and the influ-
ence of their structure on the catalytic efficiency are
currently being pursued.
Exp er im en ta l Section
Gen er a l P r oced u r es. All manipulations were performed
under a nitrogen atmosphere either using standard Schlenk
line techniques or in an Innovative Technology (Braun) Lab-
master MB-150-M drybox. Solvents were distilled over ap-
propriate drying agents and stored under nitrogen. The
following were purchased and used as received: 1-chloro-3-
propanol (Aldrich), 1-chloro-10-decanol (Aldrich), phosphorus
trichloride (Aldrich), dichlorophenylphosphine (Aldrich), chlo-
rodiphenylphosphine (Aldrich), 3-hydroxypropyldiphenylphos-
phine (Organometallics), and [RhCl(1,5-cyclooctadiene)]2 (Pres-
sure Chemicals). NMR spectra were recorded on a J EOL 270
MHz spectrometer at ambient temperature, and the chemical
shifts in ppm are relative to tetramethylsilane as an internal
standard for 1H and 13C NMR spectra and H3PO4 for 31P{1H}
NMR spectra. Coupling constants (J ) are given in Hz. Mass
spectra were obtained using a low-resolution KRATOS
MS25RSA spectrometer. MALDI-TOF mass spectra were
obtained on a Kratos Kompact Maldi 3 v 4.0 spectrometer
using LiBr/didronel or Li/gentistic acid as a matrix. Elemental
analyses were performed by Guelph Chemical Labortories,
Guelph, Ontario.
We attempted an evaluation of the catalytic activity
of some of these complexes for olefin hydrogenation that
is typically catalyzed by Wilkinson type (ClRh(PPh3)3)
complexes.12 Hydrogenation of decene in a 1:200 metal-
to-substrate ratio was carried out at 25 °C under 20 bar
H2 pressure for 1 h in benzene with metal complexes 5,
6, 8, and 9. Complex 6 represents a model rhodium
center that becomes a part of the multimetallic com-
plexes 5 (with a typical spherical structure) and 8 and
9 (with a nonspherical structure). After a catalytic run,
the organic product was extracted into hexanes, and the
conversion to decane was determined using mass spec-
OdP [O(CH2)3P P h 2]3 (1). Phosphorus oxychloride (253 mg,
1.65 mmol) was combined with 3 equiv of HO(CH2)3PPh2 (1.21
g, 4.95 mmol) in a solution mixture of 30 mL of THF and 15
mL of triethylamine cooled to 0 °C. During the addition, the
formation of a white solid (NEt3HCl) was observed. Once the
addition was complete, the reaction mixture was allowed to
warm to room temperature and stirred overnight. The white
solid was removed via vacuum filtration, and THF and
triethylamine were removed via static vacuum distillation to
afford a clear viscous liquid. Yield: 872 mg, 68%. Anal. Calcd
for C45H48O4P4: C, 69.58; H, 6.23. Found: C, 69.71; H, 5.97.
1H NMR (270 MHz, C6D6): δ (ppm) 1.61 (6H, m, -CH2-), 2.11
(6H, t,, J H-H ) 6.1 Hz, -CH2P-), 3.77 (6H, t, J H-H ) 5.9 Hz,
-CH2O-), 7.43, 7.73 (30H, m, -C6H5-). EI-MS: m/z 775.
P h P [O(CH2)3P P h 2]2 (2). Dichlorophenylphosphine (523
mg, 2.92 mmol) was dissolved in 25 mL of THF and added
dropwise to a solution of 2 equiv of HO(CH2)3PPh2 (1.43 g, 5.84
mmol) in 30 mL of THF and 15 mL of triethylamine, cooled to
0 °C. The formation of a white solid was observed during the
addition. The reaction mixture was warmed to room temper-
ature and stirred overnight. The white precipitate was re-
moved by filtration, and THF and triethylamine were removed
via static vacuum distillation to afford a clear viscous liquid.
Yield: 1.37 g, 79%. Anal. Calcd for C36H37O2P3: C, 72.79; H,
1
trometry, GC analysis, and H NMR spectroscopy. The
catalyst was recovered by precipitation using hexanes
and purified using a mixture of benzene and hexanes.
Complexes 5, 6, 8, and 9 were found to be active
catalysts for olefin hydrogenation. Complexes 8 and 9
showed turnover numbers (molprod/molcat ) 196 and 194,
respectively) and percent conversions (98 and 97%,
respectively) that were very similar to the model
complex 6 (turnover number of 196, and percent conver-
sion 98), while complex 5 showed a turnover number
(188) and percent conversion (90%) that were lower. A
detailed evaluation of this difference in activity and its
interpretation in larger multimetallic systems with
varied spherical and nonspherical structures constitute
our ongoing efforts in this area.
Con clu sion s
We have developed a simple route to a variety of
easily accessible tripodal polyphosphorus ligands. The
reaction of the latter with [RhCl(COD)]2 and the struc-
1
6.27. Found: C, 72.22; H, 6.52. H NMR (270 MHz, C6D6): δ
(ppm) 1.71 (4H, m, -CH2-), 2.06 (4H, t, J H-H ) 6.1 Hz,
-CH2P-), 3.72 (4H, t, J H-H ) 5.9 Hz, -CH2O-), 7.09, 7.64
(20H, m, -P(C6H5)2-), 7.89, 8.26 (5H, m, -O2P(C6H5)-). EI-
MS: m/z 594.
P [O(CH2)3P P h 2]3 (3). Phosphorus trichloride (1.012 g, 7.37
mmol) was dissolved in 25 mL of THF and added dropwise to
a solution of 3 equiv of HO(CH2)3PPh2 (5.437 g, 22.3 mmol) in
30 mL of THF and 15 mL of triethylamine, cooled to 0 °C. The
formation of a white solid was observed during the addition.
The reaction mixture was warmed to room temperature and
(12) (a) Osborn, J . A.; J ardine, F. H.; Young, J . F.; Wilkinson, G. J .
Chem. Soc. (A) 1966, 1711. (b) J ardine, F. H. Prog. Inorg. Chem. 1981,
28, 64. (c) Homogeneous Catalysis with Metal Phosphine Complexes;
Pignolet, L. H., Ed.; Plenum Press: New York, 1983. (d) Dickson, R.
S. Homogeneous Catalysis with Compounds of Rhodium and Iridium;
D. Reidel Publishing Company: Dordrecht, 1985. (e) Chaloner, P. A.;
Esteruelas, M. A.; J oo, F.; Oro, L. A. Homogeneous Hydrogenation;
Kluwer Academic Publishers: Dordrecht, 1994. (f) Gao, H.; Angelici,
R. J . J . Mol. Catal. A: Chem. 1999, 149, 63.

Tripodal Polyphosphorus Ligands with Rhodium
Organometallics, Vol. 21, No. 19, 2002 3865
stirred overnight. The white precipitate was removed by
filtration, and THF and triethylamine were removed via static
vacuum distillation to afford a clear viscous liquid. Yield: 3.609
g, 64%. Anal. Calcd for C45H48O3P4: C, 71.04; H, 6.36. Found:
C, 71.58; H, 6.70. 1H NMR (270 MHz, C6D6): δ (ppm) 1.70 (6H,
m, -CH2-), 2.08 (6H, t, J H-H ) 6.1 Hz, -CH2P-), 3.70 (6H, t,
J H-H ) 5.9 Hz, -CH2O-), 7.43, 7.73 (30H, m, -C6H5-). EI-
MS: m/z 760.
3.85 (10H, m, -CH2O-), 7.11, 7.75 (50H, m, P(C6H5)), 7.98,
8.30 (5H, m, P(C6H5)). EI-MS: m/z 1634.
{Rh Cl}P [O(CH2)3P P h 2]3[Rh Cl]P [O(CH2)3P P h 2]3 (9). P[O-
(CH2)3PPh2]3 (93 mg, 0.12 mmol) was dissolved in 10 mL of
benzene and added dropwise to a solution of ClRhP[(OCH2)3-
PPh2]3RhCl(1,5-C8H12)] (7) (138 mg, 0.120 mmol) in 10 mL of
benzene. The mixture was stirred for 2 h at ambient temper-
ature, after which the solvent was removed under vacuum.
The orange residue was precipitated using benzene and
hexanes to give a yellow powder. Yield: 209 mg, 97%. Anal.
Calcd for C90H96O6P4Rh2Cl2: C, 55.11; H, 5.38. Found: C,
OdP [O(CH2)3P P h 2Rh Cl(1,5-C8H12)]3 (4). OdP[O(CH2)3-
PPh2]3 (154 mg, 0.198 mmol) was dissolved in 10 mL of
benzene and added dropwise to a solution of 1.5 equiv of [(µ-
Cl)(1,5-C8H12)Rh]2 (147 mg, 0.297 mmol) in 10 mL of benzene.
The mixture was stirred for 2 h at ambient temperature, after
which the solvent was removed under vacuum. The orange
residue was precipitated using benzene and hexanes to give a
yellow powder. Yield: 287 mg, 97%. Anal. Calcd for C69H84O4P4-
1
54.75; H, 5.32. H NMR (270 MHz, C6D6): δ (ppm) 1.07-1.46
(12H, m, -CH2-), 2.21-2.61 (12H, m, -CH2P-), 3.67-3.87
(12H, m, -CH2O-), 7.14, 7.85 (60H, m, P(C6H5)), 7.98, 8.30
(5H, m, P(C6H5)). EI-MS: m/z 1799.
{Rh Cl}P [O(CH2)3P P h 2]3[Rh Cl]P h P [O(CH2)3P P h 2]2[Rh -
Cl(1,5-C8H12)] (10). {RhCl}P[O(CH2)3PPh2]3[RhCl]PPh[O(CH2)3-
PPh2]2} (8) (68 mg, 0.042 mmol) was dissolved in 15 mL of
benzene and added dropwise to a solution of 0.5 equiv of [(µ-
Cl)(1,5-C8H12)Rh]2 (10 mg, 0.021 mmol) in 10 mL of benzene.
The mixture was stirred for 3 h at ambient temperature, after
which the solvent was removed under vacuum. The orange
residue was precipitated using benzene and hexanes to give a
yellow powder. Yield: 73 mg, 93%. Anal. Calcd for C89H97O5P7-
1
Rh3Cl3: C, 54.65; H, 5.58. Found: C, 54.22; H, 6.01. H NMR
(270 MHz, C6D6): δ (ppm) 1.71 (6H, m, -CH2-), 2.20 (30H,
m, -CH2-), 3.91 (6H, t, J H-H ) 5.9 Hz, -CH2O-), 4.17, 5.86
(12H, s br, CHdCH), 7.43, 7.73 (30H, m, -C6H5-). EI-MS: m/z
1520.
OdP {O(CH2)3P P h 2(Rh Cl)P h P [O(CH2)3P P h 2]2}3 (5). Od
P[O(CH2)3PPh2RhCl(1,5-C8H12)]3 (157 mg, 0.104 mmol) was
dissolved in 10 mL of benzene and added dropwise to a solution
of 3 equiv of PhP[O(CH2)3PPh2]2 (186 mg, 0.311 mmol) in 10
mL of benzene. The mixture was stirred for 2 h at ambient
temperature, after which the solvent was removed in vacuo.
The orange residue was precipitated using benzene and
hexanes to give a yellow powder. Yield: 271 mg, 88%. Anal.
Calcd for C153H159Cl3O10P13Rh3: C, 61.75; H, 5.38. Found: C,
1
Rh3Cl3: C, 56.90; H, 5.20. Found: C, 55.70; H, 5.35. H NMR
(270 MHz, C6D6): δ (ppm) 1.08-1.40 (10H, m, -CH2-), 2.20
(8H, s, br), 2.37-2.63 (10H, m, -CH2P-), 4.17, 5.86 (4H, s,
br, -CHdCH-), 7.15, 7.76 (50H, m, P(C6H5)), 7.97, 8.25 (5H,
m, P(C6H5)). EI-MS: m/z 1874.
{Rh Cl}P [O(CH2)3P P h 2]3[Rh Cl]P [O(CH2)3P P h 2]3[Rh Cl-
(1,5-C8H12)]2 (11). {RhCl}P[O(CH2)3PPh2]3[RhCl]P[O(CH2)3-
PPh2]3 (9) (78 mg, 0.043 mmol) was dissolved in 15 mL of
benzene and added dropwise to a solution of 1 equiv of [(µ-
Cl)(1,5-C8H12)Rh]2 (20 mg, 0.043 mmol) in 10 mL of benzene.
The mixture was stirred for 3 h at ambient temperature, after
which the solvent was removed under vacuum. The orange
residue was precipitated using benzene and hexanes to give a
yellow powder. Yield: 93 mg, 94%. Anal. Calcd for C106H120O6P8-
1
61.29; H, 5.13. H NMR (270 MHz, C6D6): δ (ppm) 1.64-1.71
(18H, m, -CH2-), 2.23-2.61 (18H, m, -CH2P-), 3.87-3.91
(18H, m, -CH2O-), 7.12, 7.73 (90H, m, P(C6H5)), 7.85, 8.31
(15H, m, -O2PC6H5)). MALDI-TOF (LiBr/gentistic acid): 2970.
P h P [O(CH2)3P P h 2]2[Rh Cl] (6). PhP[O(CH2)3PPh2]2 (129
mg, 0.220 mmol) was dissolved in 10 mL of benzene and added
dropwise to a solution of 1.5 equiv of [(µ-Cl)(1,5-C8H12)Rh]2 (161
mg, 0.328 mmol) in 10 mL of benzene. The mixture was stirred
for 3 h at ambient temperature, after which the solvent was
removed in vacuo. The orange residue was precipitated using
benzene and hexanes to give a yellow powder. Yield: 147 mg,
97%. Anal. Calcd for C36H37ClO2P3Rh: C, 58.99; H, 5.08.
1
Rh4Cl4: C, 55.56; H, 5.28. Found: C, 55.06; H, 5.05. H NMR
(270 MHz, C6D6): δ (ppm) 1.12-1.53 (12H, m, -CH2-), 2.13
(16H, s, br), 2.33-2.64 (12H, m, -CH2P-), 4.25, 5.85 (8H, s,
br, -CHdCH-), 7.06, 7.94 (60H, m, P(C6H5)), 7.98, 8.30 (5H,
m, P(C6H5)). MALDI-TOF (LiBr/gentistic acid): 2295.
1
Found: C, 58.54; H, 5.36. H NMR (270 MHz, C6D6): δ (ppm)
P [OCH2)10P P h 2]3 (12). HO(CH2)10PPh2, (CH3)3SiO(CH2)10Cl:
A solution of 1-chloro-10-decanol (3.57 g, 0.018 mol) in 20 mL
of benzene was added to N,N′-diethyltrimethylsilylamine (2.69
g, 0.018 mol). The cloudy mixture was stirred at 55 °C for 14
h. The pale yellow liquid was centrifuged and the liquid
decanted off in order to remove trace amounts of solid white
precipitate. Benzene and diethylamine were removed via static
vacuum distillation to afford a pale yellow liquid. Yield: 4.62
g, 97%. Anal. Calcd for C13H29OSiCl: C, 58.94; H, 11.03.
Found: C, 58.95; H, 10.95. 1H NMR (270 MHz, C6D6): δ (ppm)
0.11 (9H, s, -CH3, 0.97-1.56 (16H, m, -CH2-), 3.13 (2H, t,
J H-H ) 6.9 Hz, -CH2Cl), 3.54 (2H, t, J H-H ) 6.3 Hz, -CH2O-).
CI-MS: m/z 265. (CH3)3SiO(CH2)10PPh2: A solution of potas-
sium diphenylphosphide (29.22 mL, 0.015 mol) in THF was
added dropwise to a solution of (CH3)3SiO(CH2)10Cl (3.87 g,
0.015 mol) in 15 mL of THF at 0 °C over a period of 4 h. The
yellowish orange solution was allowed to warm to room
temperature overnight. The solid white KCl salt produced was
removed via static vacuum distillation. Benzene was added
to extract the product, and after vacuum distillation afforded
1.71 (4H, m, -CH2-), 2.04 (4H, m, -CH2P-), 3.87 (4H, m,
-CH2O-), 7.12, 7.74 (20H, m, P(C6H5)), 8.07, 8.34 (5H, m, -O2-
PC6H5)). EI-MS: m/z 702.
{Rh Cl}P [O(CH2)3P P h 2]3[Rh Cl(1,5-C8H12] (7). P[O(CH2)3-
PPh2]3 (257 mg, 0.338 mmol) was dissolved in 10 mL of
benzene and added dropwise to a solution of 2 equiv of [(µ-
Cl)(1,5-C8H12)Rh]2 (334 mg, 0.676 mmol) in 10 mL of benzene.
The mixture was stirred for 2 h at ambient temperature, after
which the solvent was removed in vacuo. The orange residue
was precipitated using benzene and hexanes to give a yellow
powder. Yield: 379 mg, 98%. Anal. Calcd for C53H60Cl2O3P4-
Rh2: C, 55.56; H, 5.28. Found: C, 55.47; H, 5.49. 1H NMR
(270 MHz, C6D6): δ (ppm) 1.40 (6H, m, -CH2-), 2.13 (8H, s,
br, -CH2-), 2.20 (6H, m, -CH2P-), 3.57 (6H, m, -CH2O-),
4.30, 5.83 (4H, s, br, -CHdCH-) 7.11, 7.76 (30H, m, P(C6H5)).
EI-MS: m/z 1144.
{Rh Cl}P [O(CH2)3P P h 2]3[Rh Cl]P P h [O(CH2)3P P h 2]2} (8).
PhP[O(CH2)3PPh2]2 (68 mg, 0.113 mmol) was dissolved in 10
mL of benzene and added dropwise to a solution of ClRhP-
[(OCH2)3PPh2]3RhCl(1,5-C8H12)] (7) (129 mg, 0.113 mmol) in
10 mL of benzene. The mixture was stirred for 3 h at ambient
temperature, after which the solvent was removed under
vacuum. The orange residue was precipitated using benzene
and hexanes to give a yellow powder. Yield: 177 mg, 96%.
Anal. Calcd for C81H85O5P7Rh2Cl2: C, 62.78; H, 5.84. Found:
1
a pale yellow liquid. Yield: 5.91 g, 95%. H NMR (270 MHz,
C6D6): δ (ppm) 0.13 (9H, s, -CH3), 1.13-1.62 (16H, m, -CH2-
), 1.98 (2H, t, J H-H ) 7.6 Hz, -CH2P-), 3.55 (2H, t, J H-H
)
6.3 Hz, -CH2O-), 7.08, 7.47 (10H, m, -C6H5). 31P{1H} NMR
(109 MHz, C6D6): δ (ppm) -15.75 (s). CI-MS: m/z 415. HO-
(CH2)10PPh2: Anhydrous citric acid (1.38 g, 7.16 mmol) was
dissolved in 15 mL of methanol, and the solution was trans-
ferred via syringe into a Schlenk flask containing (CH3)3SiO-
1
C, 62.59; H, 5.67. H NMR (270 MHz, C6D6): δ (ppm) 1.10-
1.41 (10H, m, -CH2-), 2.21-2.61 (10H, m, -CH2P-), 3.57-

3866 Organometallics, Vol. 21, No. 19, 2002
Peori and Kakkar
(CH2)10PPh2 (2.97 g, 7.16 mmol), resulting in a cloudy mixture.
The latter was stirred at ambient temperature until a clear
solution was formed. Methanol was then removed via static
vacuum distillation, and benzene was added to extract the
product. Benzene was removed via static vacuum distillation
to afford a pale yellow viscous liquid. Yield: 2.23 g, 91%. Anal.
Calcd for C22H31OP: C, 77.26; H, 9.14. Found: C, 76.70; H,
of [(µ-Cl)(1,5-C8H12)Rh]2 (109 mg, 0.253 mmol) in 15 mL of
benzene. The mixture was stirred for 1 h at ambient temper-
ature, after which the solvent was removed under vacuum.
The orange residue was precipitated using benzene and
hexanes to give a yellow powder. Yield: 229 mg, 89%. Anal.
Calcd for C58H138O3P4Rh4Cl4: C, 57.66; H, 6.81. Found: C,
1
57.40; H, 6.82. H NMR (270 MHz, C6D6): δ (ppm) 0.86-1.61
1
8.78. H NMR (270 MHz, C6D6): δ (ppm) 1.11-1.55 (16H, m,
(48H, m, -CH2-), 2.17 (32H, s, b, -CH2CH2-), 2.57 (6H, m,
-CH2P-), 3.57 (6H, m, -CH2O-), 4.34, 5.78 (16H, s, b, -CHd
CH-), 7.10, 7.49 (30H, m, C6H5). MALDI-TOF (LiBr/gentistic
acid): 2045.
-CH2-), 1.99 (2H, t, J H-H ) 7.6 Hz, -CH2P-), 3.46 (2H, t,
J H-H ) 6.3 Hz, -CH2O-), 7.09, 7.47 (10H, m, C6H5). 31P{1H}
NMR (109 MHz, C6D6): δ (ppm) -15.75 (s). EI-MS: m/z 342.
Phosphorus trichloride (0.505 g, 3.68 mmol) was dissolved in
25 mL of THF and added dropwise using a dropping funnel to
a solution of 3 equiv of HO(CH2)10PPh2 (3.78 g, 11.1 mmol) in
30 mL of THF and 15 mL of triethylamine that was cooled to
0 °C. Once the addition was complete, the reaction mixture
was allowed to warm to room temperature and left stirring
overnight. A white precipitate that was formed during the
reaction was removed via vacuum filtration, and THF/trieth-
ylamine was removed via extensive static vacuum distillation
to afford a viscous liquid. Yield: 2.39 g, 62%. 1H NMR (270
MHz, C6D6): δ (ppm) 1.15-1.58 (48H, m, -CH2-), 2.02 (6H,
t, J H-H ) 7.6 Hz, -CH2P-), 3.68 (6H, t, J H-H ) 6.3 Hz,
-CH2O-), 7.09, 7.47 (30H, m, C6H5). EI-MS: m/z 1055.
P h P [O(CH2)10P P h 2]2 (13). PhPCl2 (489 mg, 2.73 mmol)
was dissolved in 25 mL of THF and added dropwise using a
dropping funnel to a solution of 2 equiv of HO(CH2)10PPh2 (1.87
g, 5.46 mmol) in 30 mL of THF and 15 mL of triethylamine
that was cooled to 0 °C. Once the addition was complete, the
reaction mixture was allowed to warm to room temperature
and left stirring overnight. A white precipitate that was formed
during the reaction was removed via vacuum filtration, and
THF/triethylamine was removed via extensive static vacuum
distillation to afford a viscous liquid. Yield: 1.52 g, 71%. Anal.
Calcd for C50H65O2P3: C, 75.92; H, 6.28. Found: C, 75.10; H,
[1,5-C8H 12)ClR h ]P h P [O(CH 2)10P P h 2R h Cl(1,5-C8H 12)]2
(15). PhP[OCH2)3PPh2]2 (12) (154 mg, 0.195 mmol) was
dissolved in 10 mL of benzene and added dropwise to a solution
of 1.5 equiv of [(µ-Cl)(1,5-C8H12)Rh]2 (144 mg, 0.292 mmol) in
15 mL of benzene. The mixture was stirred for 3 h at ambient
temperature, after which the solvent was removed under
vacuum. The orange residue was precipitated using benzene
1
and hexanes to give a yellow powder. Yield: 268 mg, 90%. H
NMR (270 MHz, C6D6): δ (ppm) 1.14-1.57 (32H, m, -CH2-),
2.03 (4H, m, -CH2P-), 3.69 (4H, m, -CH2O-), 4.34, 5.78
(16H, s, b, -CHdCH-), 7.10, 7.49 (20H, m, C6H5), 7.87, 8.28
(5H, m, C6H5). EI-MS: m/z 1529.
Hyd r ogen a tion of Decen e. A typical run for the hydro-
genation of decene using complex 6 is described here. A
solution of 25 mg (0.035 mmol) of 6 and 1 g of decene (7.13
mmol) in 10 mL of benzene was placed in a hydrogen bomb,
pressurized with H2 (20 bar), and left to react for 1 h at room
temperature. Hexane (5 mL) was then added to precipitate
the catalyst, which was removed by filtration. The hexane and
benzene were removed from the filtrate by static vacuum
distillation to afford 998 mg of decane. It was characterized
by GC, MS, and 1H NMR. Turnover number (molsub/molcat) )
1
196. H NMR (270 MHz, C6D6): δ 0.93 (6H, t, J H-H ) 5.9 Hz,
-CH3), 1.44 (16H, s, -CH2-). GC retention time 11.29 min
(90 °C, He carrier gas, 14 psi, flame ionization detector, Ph-
Me siloxane capillary column). EI-MS: m/z 142.
1
6.33. H NMR (270 MHz, C6D6): δ (ppm) 1.14-1.57 (32H, m,
-CH2-), 2.03 (4H, t, J H-H ) 7.6 Hz, -CH2P-), 3.69 (4H, t,
J H-H ) 6.3 Hz, -CH2O-), 7.10, 7.49 (20H, m, C6H5), 7.87, 8.28
(5H, m, C6H5). EI-MS: m/z 792.
Ack n ow led gm en t. We thank NSERC (Canada) and
FCAR (Quebec, Canada) for financial support.
[1,5-C8H12)ClRh ]P [O(CH2)10P P h 2Rh Cl(1,5-C8H12)]3 (14).
P[OCH2)3PPh2]3 (12) (134 mg, 0.126 mmol) was dissolved in
15 mL of benzene and added dropwise to a solution of 2 equiv
OM020098L