Cage phosphinites: Ligands for efficient nickel-catalyzed hydrocyanation of 3-pentenenitrile

Article abstract of DOI:10.1021/om101023e

The cage monophosphinites CgPOR {where CgP = 6-phospha-2,4,8-trioxa- adamantane and R = C₆H₅ (L_a); 2-C ₆H₄CH₃ (L_b); 2,4,6-C ₆H₂(CH₃)₃ (L_c); 2,4-C₆H₃^tBu₂ (L_d); CH₃ (L_e); CH₂CF₃ (L_f)} and diphosphinites CgPZPCg {where ZH₂ = 2,2′-biphenol (L _g) or 1,2-benzenedimethanol (L_h)} have been made from CgPBr and the corresponding alcohol or phenol. The cage phosphinites are remarkably stable to water. All the ligands L_a-h have been tested for nickel(0)-catalyzed hydrocyanation of 3-pentenenitrile in the presence of Lewis acids (ZnCl₂, Ph₂BOBPh₂, or ⁱBu₂AlOAlⁱBu₂), and tentative structure-activity relationships are suggested. The hydrocyanation activities obtained with catalysts derived from monophosphinite L_f (with ⁱBu₂AlOAlⁱBu₂) and diphosphinite L_h (with ZnCl₂) are comparable with the commercial catalyst based on P(OTol)₃. The complexes trans-[PtCl ₂(L)₂] where L = L_a (1a), L_e (1e), and L_f (1f) and the chelate cis-[PtCl₂(L_h)] (1h) are reported. From the ν_CO values for the complexes trans-[RhCl(CO)(L_a-f)₂] (2a-f), it is concluded that ligand L_f is the most phosphite-like of the monophosphinites. Treatment of [Ni(cod)₂] (cod = 1,5-cyclo-octadiene) with L _h leads to a mixture of products, one of which was characterized as the binuclear [Ni₂(L_h)₂(μ-cod)] (3h). The crystal structures of L_h, 1a, 1e, 1f, 1h?2CH₂Cl ₂, and 3h?3C₆H₅CH₃ are reported.

Full text of DOI:10.1021/om101023e

974 Organometallics 2011, 30, 974–985
DOI: 10.1021/om101023e
Cage Phosphinites: Ligands for Efficient Nickel-Catalyzed
Hydrocyanation of 3-Pentenenitrile
Igor S. Mikhel,† Michael Garland,† Jonathan Hopewell,† Sergio Mastroianni,‡
Claire L. McMullin,† A. Guy Orpen,† and Paul G. Pringle*,†
‡
†School of Chemistry, University of Bristol, Cantocks Close, Bristol BS8 1TS, U.K., and Rhodia, Centre de
ꢀ
Recherches et Technologies de Lyon, 85 Rue des Freres Perrets, 69192 Saint-Fons Cedex, France
Received October 29, 2010
The cage monophosphinites CgPOR {where CgP=6-phospha-2,4,8-trioxa-adamantane and R=
t
C6H5 (La); 2-C6H4CH3 (Lb); 2,4,6-C6H2(CH3)3 (Lc); 2,4-C6H3 Bu2 (Ld); CH3 (Le); CH2CF3 (Lf)} and
diphosphinites CgPZPCg {where ZH2=2,20-biphenol (Lg) or 1,2-benzenedimethanol (Lh)} have been
made from CgPBr and the corresponding alcohol or phenol. The cage phosphinites are remarkably
stable to water. All the ligands La-h have been tested for nickel(0)-catalyzed hydrocyanation of
3-pentenenitrile in the presence of Lewis acids (ZnCl2, Ph2BOBPh2, or iBu2AlOAliBu2), and tentative
structure-activity relationships are suggested. The hydrocyanation activities obtained with catalysts
i
derived from monophosphinite Lf (with Bu2AlOAliBu2) and diphosphinite Lh (with ZnCl2) are
comparable with the commercial catalyst based on P(OTol)3. The complexes trans-[PtCl2(L)2] where
L=La (1a), Le (1e), and Lf (1f) and the chelate cis-[PtCl2(Lh)] (1h) are reported. From the νCO values
for the complexes trans-[RhCl(CO)(La-f)2] (2a-f), it is concluded that ligand Lf is the most
phosphite-like of the monophosphinites. Treatment of [Ni(cod)2] (cod=1,5-cyclo-octadiene) with
Lh leads to a mixture of products, one of which was characterized as the binuclear [Ni2(Lh)2(μ-cod)]
(3h). The crystal structures of Lh, 1a, 1e, 1f, 1h 2CH2Cl2, and 3h 3C6H5CH3 are reported.
3
3
Introduction
of the most successful industrial applications of homoge-
neous catalysis.5,6 Tritolylphosphite (I) was the industrial
ligand of choice6,7 for this process before the emergence in
the 1990s of the generation of catalysts based on bulky
diphosphites such as II (Chart 1).8 The great majority of
academic studies on butadiene hydrocyanation have con-
cerned the conversion of butadiene to 3-pentenenitrile (3-
PN), the first step in Scheme 1, although the hydrocyanation
Phosphite ligands, P(OR)3, have been at the center of
developments in coordination chemistry and homogeneous
catalysis for over 50 years.1 The π-acceptor capacity of
phosphites makes them good ligands for metals in low
oxidation states2 and can increase the electrophilicity of
metal centers.3 Tolman’s landmark article4 on the system-
atization of ligand stereoelectronic effects was driven by a
need to understand the ligand effects in DuPont’s nickel-
phosphite-catalyzed hydrocyanation of butadiene to adipo-
nitrile (ADN) (summarized in Scheme 1), which remains one
(8) (a) Tam, W.; Kreutzer, K. A.; McKinney, R. J. (DuPont) World
Patent 14659, 1995. (b) Baker, M. J.; Harrison, K. N.; Orpen, A. G.;
Pringle, P. G.; Shaw, G. J. Chem. Soc., Chem. Commun. 1991, 803.
ꢁ
(9) Vallee, C.; Chauvin, Y.; Basset, J.-M.; Santini,a, C. C.; Galland,
J.-C. Adv. Synth. Catal. 2005, 347, 1835–1847.
*To whom correspondence should be addressed. E-mail: paul.
pringle@bristol.ac.uk.
(10) (a) Birkholz, M. N.; Freixa, Z.; van Leeuwen, P. W. N. M. Chem.
Soc. Rev. 2009, 38, 1099. (b) Gillespie, J. A.; Dodds, D. L.; Kamer, P. C. J.
Dalton Trans. 2010, 39, 2751, and references therein. Birkholz, M. N.;
Freixa, Z.; van Leeuwen, P. W. N. M. Chem. Soc. Rev. 2009, 38, 1099.
(1) (a) Hartwig, J. F. Organotransition Metal Chemistry; University
Science Books: Sausalito, CA, USA, 2010. (b) van Leeuwen, P. W. N. M.
Homogeneous Catalysis: Understanding the Art; Springer-Verlag: New
€
(11) Bini, L.; Muller, C.; Wilting, J.; von Chrzanowski, L.; Spek,
€
York, 2004. (c) Borner, A. Phosphorus Ligands in Asymmetric Catalysis;
A. L.; Vogt, D. J. Am. Chem. Soc. 2007, 129, 12622.
(12) van der Vlugt, J. I.; Hewat, A. C.; Neto, S.; Sablong, R.; Mills,
€
A. M.; Lutz, M.; Spek, A. L.; Muller, C.; Vogt, D. Adv. Synth. Catal.
Wiley-VCH: Weinheim, Germany, 2008.
(2) (a) Dias, P. B.; Minas de Piedade, M. E.; Martinho Simoes, J. A.
~
Coord. Chem. Rev. 1994, 135-136, 737. (b) Baker, M. J.; Harrison, K. N.;
Orpen, A. G.; Pringle, P. G.; Shaw, G. J. Chem. Soc., Dalton Trans. 1992,
2607. (c) Crispini, A; Harrison, K. N.; Orpen, A. G.; Pringle, P. G.;
Wheatcroft, J. R. J. Chem. Soc., Dalton Trans. 1996, 1069, and references
therein.
(3) Yamakawa, T.; Fujita, T.; Shinoda, S. Chem. Lett. 1992, 21, 905.
(4) Tolman, C. A. Chem. Rev. 1977, 77, 313.
(5) Krill, S. In Applied Homogeneous Catalysis with Organometallic
Compounds, 2nd ed.; Cornils, B., Ed.; Wiley-VCH: Weinheim, Germany,
2002.
2004, 346, 993.
€
(13) Gothlich, A. P. V.; Tensfeldt, M.; Rothfuss, H.; Tauchert, M. E.;
Haap, D.; Rominger, F.; Hofmann, P. Organometallics 2008, 27, 2189.
(14) Some representative examples: (a) Saha, B.; RajanBabu, T. V.
Org. Lett. 2006, 8, 4657. (b) Wilting, J.; Janssen, M.; M€uller, C.; Vogt, D. J.
Am. Chem. Soc. 2006, 128, 11374. (c) Horiuchi, T.; Shirakawa, E.; Nozaki,
K.; Takaya, H. Tetrahedron: Asymmetry 1997, 8, 57. (d) RajanBabu, T. V.;
Casalnuovo, A. L. J. Am. Chem. Soc. 1996, 118, 6325. (e) Baker, M. J.;
Pringle, P. G. J. Chem. Soc., Chem. Commun. 1991, 1292. (f) Elmes, P. S.;
Jackson, W. R. Aust. J. Chem. 1982, 35, 2041. (g) Wilting, J.; Janssen, M.;
M€uller, C.; Lutz, M.; Spek, A. L.; Vogt, D. Adv. Synth. Catal. 2007, 349,
350. (h) de Greef, M.; Breit, B. Angew. Chem., Int. Ed. 2009, 48, 551. (i)
Goertz, W.; Kamer, P. C. J.; Van Leeuwen, P. W. N. M.; Vogt, D. Chem.;
Eur. J. 2001, 7, 1614. (j) Casalnuovo, A. L.; RajanBabu, T. V.; Ayers, T. A.;
Warren, T. H. J. Am. Chem. Soc. 1994, 116, 9869.
(6) Tolman, C. A. J. Chem. Educ. 1986, 63, 199.
(7) (a) Chia, Y.; Drinkard, W. C.; Squire, E. N. (Du Pont) U.S. Patent
3766237, 1973. (b) Tolman, C. A.; McKinney, R. J.; Seidel, W. C.;
Druline, J. D.; Stevens, W. R. Adv. Catal. 1985, 33, 1, and references
therein.
r
pubs.acs.org/Organometallics
Published on Web 02/10/2011
2011 American Chemical Society

Article
Organometallics, Vol. 30, No. 5, 2011 975
Scheme 1
Chart 1
of 3-PN to ADN is a more challenging reaction, requiring
isomerization to 4-pentenenitrile (4-PN) followed by
hydrocyanation.9
Rigid-backboned diphosphines10,11 such as III and diphos-
phonites12,13 such as IV have been shown to be effective
ligands for the hydrocyanation of butadiene to 3-PN. The
hydrocyanation of other alkenes (particularly asymmetric
hydrocyanation) has been a topic of continuing interest,14
and all of these processes use the same classes of phosphorus
ligands that are used for butadiene hydrocyanation.
The rational design of improved ligands for hydrocyana-
tion has been an enduring goal.10,15,16 A significant limita-
tion for the application of phosphites (and other P-O-
containing ligands) in hydrocyanation and other catalyses
is their susceptibility to hydrolysis, and this has led to
research to design phosphines, with kinetically inert P-C
bonds, which could mimic phosphites.10,17
Tertiary phosphines based on the phospha-adamantane
cage (denoted CgPR in Chart 2) have been shown to be
kinetically inert and stereoelectronically similar to a bulky
phosphonite (RO)2PR.18,19 Moreover, ligands incorporating
the CgP moiety have proved to be effective in many catalytic
reactions.20 We reasoned that cage phosphinites of the type
CgPOR (Chart 2) should have greater π-acceptor capacity
than CgPR and show here that this expectation is realized
and that air-stable, monodentate and bidentate cage phos-
phinite ligands are effective for nickel(0)-catalyzed hydro-
cyanation of 3-pentenenitrile to ADN. Some of this work has
formed part of a patent.21
Chart 2
were purified by flash chromatography and have been char-
acterized by a combination of high-resolution mass spectro-
metry and 31P, 13C, 1H, and 19F NMR spectroscopy (see
Experimental Section for the data). The 31P NMR spectrum
of the o-xylene-linked diphosphinite Lh showed two singlets in a
1:1 ratio consistent with the presence of rac and meso diaster-
eoisomers, associated with the R- and β-enantiomeric forms of
the CgP moiety.20 The 31P NMR spectrum in CD2Cl2 of a
recrystallized sample of the 2,20-biphenyl-linked diphosphinite
Lg at 25 °C showed two singlets at δ 83.3 and 80.5 in a ratio of
ca. 22:1, corresponding to the rac and meso isomers. However
at þ20 °C, a single broad resonance (w1/2 ca. 100 Hz) at δ 82.7
was observed that resolved at -60 °C into four singlets at δ
89.8, 83.8, 82.4, and 78.6 in the approximate ratio of 35:1:10:1,
respectively. This is consistent with the presence of three
diastereoisomers, resulting from arrested rotation about the
biphenyl C-C bond, introducing an extra element of chirality
(labeled R and S for the biaxial dissymmetry) and giving rise to
two singlets (δ 89.8 and 82.4) for the two C2-symmetric isomers
(RRR/βSβ and RSR/βRβ forms) and two singlets (δ 83.8 and
Results and Discussion
Ligand Synthesis. The two-step routes shown in Scheme 2
gave generally good yields (>60% overall) of cage mono-
phosphinites La-f and diphosphinites Lg,h. The new ligands
(15) Maldonado, A. G.; Hageman, J. A.; Mastroianni, S.; Rothenberg,
G. Adv. Synth. Catal. 2009, 351, 387.
(16) (a) Tauchert, M. E.; Kaiser, T. R.; Goethlich, A. P. V.; Rominger,
F.; Warth, D. C. M.;Hofmann, P. ChemCatChem 2010, 2, 674. (b) Bini, L.;
Muller, C.; Vogt, D. Chem. Commun. 2010, 46, 8325.
(17) Clarke, M. L.; Ellis, D.; Mason, K. L.; Orpen, A. G.; Pringle,
P. G.; Wingad, R. L.; Zaher, D.; A. Baker, R. T. Dalton Trans. 2005,
1294.
(18) Baber, R. A.; Clarke, M. L.; Heslop, K. M.; Marr, A. C.; Orpen,
A. G.; Pringle, P. G.; Ward, A.; Zambrano-Williams, D. E. Dalton
Trans. 2005, 1079.
(19) Downing, J. H.; Floure, J.; Heslop, K.; Haddow, M. F.;Hopewell,
J.; Lusi, M.; Phetmung, H.; Orpen, A. G.; Pringle, P. G.; Pugh, R. I.;
Zambrano-Williams, D. Organometallics 2008, 27, 3216.
(20) Hopewell, J.; Jankowski, P.; McMullin, C. L.; Orpen, A. G.;
Pringle, P. G. Chem. Commun 2010, 46, 100, and references therein.
(21) Mastroianni, S.; Mikhel, I.; Pringle, P. (Rhodia) World Patent
WO 2010/102962, 2010.

976 Organometallics, Vol. 30, No. 5, 2011
Mikhel et al.
Scheme 2a
Figure 1. Thermal ellipsoid plot of Lh. Displacement ellipsoids
are shown at the 50% probability level, and all hydrogen atoms
˚
have been removed for clarity. Selected bond lengths (A) and
angles (deg): P-C2, 1.8656(12); P-C9, 1.8720(12); P-O4, 1.65-
16(8); C2-P-C9, 93.03(5).
complexes of the cage phosphinites La-h in the presence of a
Lewis acid using acetone cyanohydrin as the source of HCN;
the results are given in Table 1. The process involves an
isomerization of 3-PN to 4-PN followed by hydrocyanation
(Scheme 3). The byproduct arises from isomerization of 3-PN
to 2-PN and addition of HCN to 3-PN to give ethylsuc-
cinonitrile (ESN) or 2-methylglutaronitrile (2-MGN). The
yield in Table 1 refers to the conversion of 3-PN to dinitriles
(ADN, 2-MGN, and ESN) under the standard reaction
conditions (see Experimental Section), and the linearity is the
proportion of the dinitrile product that is the desired ADN.
The yields obtained with all the aryl phosphinites, CgPO-
Ar (entries 1-4) were very low but were greater than 1%,
making the CgPOAr ligands more effective for this catalysis
than CgPPh, where only traces of dinitriles were detected
(entry 17). Increasing the steric bulk of the CgPOAr ligand
appears to be detrimental to the yield.
a Conditions: (i) Br2 in CH2Cl2 at 0 °C. (ii) ROH þ BuLi in THF at
0 °C. (iii) Diol (2,20-biphenol or 1,2-benzenedimethanol) þ 2 BuLi in
THF at 0 °C.
The catalyst derived from CgPOMe (entries 5-7) gave
significantly higher yields (up to 19%) than the CgPOAr-
derived catalysts. The yields were higher still (up to 36%)
using the CgPOCH2CF3 ligand (entries 8-10). The tentative
conclusions from the catalysis results for the monodentate
CgPOR ligands are that the hydrocyanation activity is (1)
greater when R=alkyl than when R=aryl; (2) greater with
smaller R groups when R=aryl; (3) greater with more
electron-withdrawing R groups when R=alkyl.
Diphosphites have many advantages over monopho-
sphites in terms of catalyst stability, activity, and selectivity,
which has led to their adoption for commercial hydrocyana-
tion catalysis.8 The cage diphosphinites Lg and Lh were
screened for hydrocyanation catalysis, and the results are
given in Table 1. The results with Lg (entries 11-13) were
disappointingly similar to those with the monodentate ana-
logue La (entries 1-3). The 2,20-biphenyl linking group is a
common structural element in the highly successful dipho-
sphite ligands8 but evidently does not improve the catalyst
78.6, with 7JPP not resolved) for the inequivalent P atoms in the
C1-symmetric isomer (RRβ/RSβ form).
Phosphinites are reputed to be sensitive to hydrolysis22
(eq 1), and indeed we found that a sample of Ph2POMe
stirred in 2% aqueous MeCN at ambient temperature was
50% hydrolyzed to Ph2P(O)H after 55 min. By contrast,
under similar conditions, the CgPOMe showed no detectable
signs (by 31P NMR) of hydrolysis after 17 days. The inertness
of CgPOMe to hydrolysis may be due to the methyl groups
on the cage (which are held rigidly in the vicinity of the P
atom), providing a hydrophobic environment and steric
protection to the phosphorus.
Crystals of Lh were grown from a saturated solution in a
mixture of CH2Cl2, ethyl acetate, and hexane. It crystallized
in space group C2/c, and the molecule has crystallographic
2-fold symmetry (Figure 1).
HydrocyanationCatalysis. A simplified scheme for the com-
mercialized hydrocyanation of butadiene to ADN catalyzed
by nickel(0) complexes is shown in Scheme 1. We have studied
the conversion of 3-PN to ADN catalyzed by nickel(0)
(23) Bite angle and flexibility differences between ligands Lg and Lh
should be important in understanding the catalytic results since it has
been established that even small changes in natural bite angles can have a
large effect on hydrocyanation activity and selectivity with nickel-
diphosphine catalysts. However, defining a bite angle for ligands with
diolate backbones is frustrated by the large number of conformations
with similar energy; see: van Leeuwen, P. W. N. M.; Kamer, P. C. J.;
Reek, J. N. H.; Dierkes, P. Chem. Rev. 2000, 100, 2741.
(22) Pryjomska, I.; Bartosz-Bechowski, H.; Ciunik, Z.; Trzeciak,
ꢁ
A. M.; Ziozkowski, J. J. Dalton Trans. 2006, 213.

Article
Organometallics, Vol. 30, No. 5, 2011 977
Scheme 3
Table 1. Hydrocyanation Catalysis Results with Cage
Phosphinitesa
Scheme 4
entry
L
Lewis Acid
yield
linearity
1
2
3
4
5
6
7
8
La
Lb
Lc
Ld
Le
Ph2BOBPh2
Ph2BOBPh2
Ph2BOBPh2
Ph2BOBPh2
ZnCl2
3
2
1
1
4
19
7
3
36
15
1
73
b
b
b
75
64
79
58
61
TIBAO
Ph2BOBPh2
ZnCl2
TIBAO
Ph2BOBPh2
ZnCl2
TIBAO
Ph2BOBPh2
ZnCl2
TIBAO
Lf
Lg
Lh
9
10
11
12
13
14
15
16
17
18d
75
b
b
2
5
79
75
56
40
12
6
<1
60
Ph2BOBPh225) on the activity depends on the catalyst;
for example, TIBAO gives the highest rates for the catalysts
based on the monodentates Le and Lf, while ZnCl2 gives
the highest rates for the catalysts based on the bidentate Lh.
The greatest linearity was consistently obtained with the
bulky Ph2BOBPh2. The hydrocyanation results reported
for the commercial catalyst based on P(OTol)3 (entry 18)26
put the results obtained with the cage phosphinites into
perspective, showing thatthe performance ofthe newcatalysts
approaches that of the DuPont catalyst under the same
conditions.
Ph2BOBPh2
73
c
b
CgPPh
P(OTol)3
ZnCl2
82
a For reaction conditions, see Experimental Section. TIBAO=tetra-
isobutylaluminoxane. Ph2BOBPh2 has recently been reported.25 b With
low-yielding catalytic runs, the error in the selectivity was too high to
give meaningful numbers. c With ZnCl2, TIBAO, or Ph2BOBPh2, only
traces of dinitriles were detected. d Catalysis carried out under the same
conditions as for entries 1-17 using acetone cyanohydrin and results
reported in ref 26.
The mechanism proposed for Ni-catalyzed hydrocyana-
tion features nickel(II) and nickel(0) intermediates in a
range of geometries, and the details of the binding of the
ligands to the metal in terms of the σ/π-bonding and bite
angle effects are critical to understanding the efficacy of the
catalyst.27The successful application of the cage phosphi-
nites in nickel-catalyzed hydrocyanation described above
prompted us to investigate the bonding of these new ligands
(especially Lf and Lh, which gave the best hydrocyanation
catalysts) to transition metals, in particular platinum(II),
rhodium(I), and nickel(0).
Platinum(II) Complexes. The complexes trans-[PtCl2(La)2]
(1a), trans-[PtCl2(Le)2] (1e), trans-[PtCl2(Lf)2] (1f), and the
chelate cis-[PtCl2(Lh)] (1h) were prepared according to
Scheme 4 (see Experimental Section for the characterizing
data). The chirality of the CgP moiety leads to the 31P and
195Pt NMR spectra of 1a, 1e, 1f, and 1h showing two signals
with similar δ and JPtP values in ca. 1:1 ratio for the rac and
meso diastereomeric products, as expected.18 The 195Pt spec-
tra consisted of two triplets in each case, confirming the PtP2
structures. The trans geometry of 1a, 1e, and 1f was assigned
on the basis of the JPtP of ca. 2800 Hz and the presence of
performance in the case of the cage phosphinites described
here. The best results, with a yield of 40% and linearity
of 75%, were obtained using the o-xylene-linked diphosphi-
nite, Lh (entries 14-16, Table 1). The conclusions from the
catalysis results for the bidentate ligands CgPOZOPCg
(both of which would give nine-membered chelates) are
that hydrocyanation activity is sensitive to the backbone
linker group (Z) and higher when Z = dialkyl than when
Z=diaryl.23
Lewis acid cocatalysts increase the rate and selectivity of
3-PN hydrocyanation, and this has been explained mecha-
nistically in terms of the coordination of the Lewis acid
to the nitrogen of the Ni-CN intermediate prior to the
alkyl migration step.6,24 From the results presented in
Table 1, the effect of the Lewis acid (ZnCl2, TIBAO, or
(24) (a) Tolman, C. A.; Seidel, W. C.; Druliner, J. D.; Domaille, P. J.
Organometallics 1984, 3, 33. (b) Bini, L.; Pidko, E. A.; M€uller, C.; van
Santen, R. A.; Vogt, D. Chem.;Eur. J. 2009, 15, 8768. (c) Tolman, C. A.;
McKinney, R. J.; Siedel, W. C.; Druliner, J. D.; Stevens, W. R. Adv. Catal.
1985, 33, 1. (d) McKinney, R. J.; Nugent, W. A. Organometallics 1989, 8,
2871.
(25) (a) Mastroianni, S. (Rhodia) World Patent WO 2009/092639,
2009. (b) Mastroianni, S. (Rhodia) World Patent WO 2010/086246,
2010.
€
(27) Bini, L.; Muller, C.; Vogt, D. ChemCatChem 2010, 2, 590.
(26) Mastroianni, S. (Rhodia) World Patent WO 2009/153171, 2009.

978 Organometallics, Vol. 30, No. 5, 2011
Mikhel et al.
Figure 2. Thermal ellipsoid plot of one of the two independent
molecules of 1a. Displacement ellipsoids are shown at the 50%
probability level, and all solvent and hydrogen atoms have been
Figure 4. Thermal ellipsoid plot of one of the two independent
molecules of 1f. Displacement ellipsoids are shown at the 50%
probability level, and all hydrogen atoms have been removed for
˚
removed for clarity. Selected bond lengths (A) and angles (deg):
˚
clarity. Selected bond lengths (A) and angles (deg): Pt1-P1,
Pt1-P1, 2.3023(6); Pt1-Cl1, 2.3080(6); P1-C2, 1.867(2); P1-
C9, 1.858(2); P1-O4, 1.6166(17); C2-P1-C9, 95.31(11);
P1-Pt1-Cl1, 94.23(2).
2.3061(6); Pt1-Cl1, 2.3131(6); P1-C2, 1.875(2); P1-C9, 1.867(2);
P1-O4, 1.6190(18); C2-P1-C9, 94.94(11); P1-Pt1-Cl1,
92.37(2).
the reactions; for example, the 31P NMR of the product
obtained upon treatment of [PtCl2(cod)] with La showed, in
addition to the signals for rac and meso 1a, minor signals (ca.
15% of the total) for the cis isomers (76.6, 1JPPt=4101 Hz
and 81.4, 1JPPt=4198 Hz). The cis chelate structure of 1h was
supported by the JPtP of ca. 4200 Hz;28 further study un-
covered the fluxionality of 1h (see below).
The crystal structures of monophosphinite complexes 1a,
1e, and 1f have been determined (see Figures 2-4). Crystals
of 1a were grown from a saturated CH2Cl2/ethyl acetate
solution and crystallized in space group P21/c. Crystals of 1e
were grown from a saturated CH2Cl2/ether solution and
crystallized in space group P1, while crystals of 1f were
grown from a saturated ethyl acetate/hexane solution and
also crystallized in space group P1. All three of the
trans-[PtCl2(CgPOR)2] structures (1a, 1e, and 1f) are meso
isomers; that is, each complex contains both the R and β
enantiomers of the cages.20 The third substituent (OR)
adopts a gauche conformation in each structure. The Pt-P
distances in 1a and 1f are very similar to each other and are
Figure 3. Thermal ellipsoid plot of one of the two independent
molecules of 1e. Displacement ellipsoids are shown at the 50%
probability level, and all solvent and hydrogen atoms have been
˚
removed for clarity. Selected bond lengths (A) and angles (deg):
Pt1-P1, 2.316(2); Pt1-Cl1, 2.297(2); P1-C2, 1.862(9); P1-C9,
1.862(9); P1-O4, 1.574(7); C2-P1-C9, 94.9(4); P1-Pt1-Cl1,
86.78(8).
˚
slightly shorter (ca. 0.01 A) than in 1e.
Crystals of 1h 2CH2Cl2 were grown from a saturated
virtual triplets for some of the 13C signals (see Experimental
Section).28 In the cases of 1a and 1e, a small amount of a
second product assigned to the cis isomer was detected in the
31P NMR spectra recorded of the reaction mixtures during
3
CH2Cl2/ethyl acetate solution and crystallised in space
group P21/c, with two CH2Cl2 solvent molecules in the
asymmetric unit. The structure of the chelate complex 1h
(see Figure 5) is of the rac isomer with the cage configura-
tions either RR or ββ. The conformation of the PO-xylyl
moiety in 1h is significantly different from the free Lh
structure, indicating that the ligand does not crystallize
preorganized for complexation. The P-O-C-C torsion
angle changes from -173.33(7)° to -150.3(5)°/-86.9(8)°
(28) (a) Olsson, D.; Arunachalampillai, A.; Wendt, O. F. Dalton
Trans. 2007, 5427. (b) Bergamini, P.; Bertolasi, V.; Milani, F. Eur. J. Inorg.
Chem. 2004, 1277. (c) Nazarov, A. A.; Hartinger, C. G.; Arion, V. B.; Giester,
G.; Keppler, B. K. Tetrahedron 2002, 58, 8489. (d) Balakrishna, M. S.;
Panda, R.; Mague, J. T. J. Chem. Soc., Dalton Trans. 2002, 4617. (e)
Atherton, M. J.; Fawcett, J.; Hill, A. P.; Holloway, J. H.; Hope, E. G.; Russell,
D. R.; Saunders, G. C.; Stead, R. M. J. J. Chem. Soc., Dalton Trans. 1997,
1137. (f) Sharma, R. K.; Samuelson, A. G. Tetrahedron: Asymmetry 2007,
18, 2387. (g) Ruhland, K.; Br€uck, A.; Herdtweck, E. Eur. J. Inorg. Chem.
when the ligand is bound to the Pt(II) center in 1h 2CH2Cl2.
3
As a result of chelation, the O-CH2-xylyl-CH2-O back-
bone no longer possesses the C2 symmetry it had in Lh; in 1h
the O-C-C-C torsion angles are 84.6(8)° and -52.2(9)° for
Pt1-P1-O4-C11 and Pt1-P2-O8-C18, respectively (cf.
-84.84(15)° in Lh). The unsymmetrical chelate conformation
€
€ €
2007, 944. (h) Fild, M.; Thone, C.; Totos, S. Eur. J. Inorg. Chem. 2004, 749.
(i) Bergamini, P.; Bertolasi, V.; Cattabriga, M.; Ferretti, V.; Loprieno, U.;
Mantovani, N.; Marvelli, L. Eur. J. Inorg. Chem. 2003, 918. (j) Dyer, P. W.;
Fawcett, J.; Hanton, M. J.; Kemmitt, R. D. W.; Padda, R.; Singh, N. Dalton
Trans. 2003, 104.

Article
Organometallics, Vol. 30, No. 5, 2011 979
Figure 6. 13C NMR (125 MHz) signal for the CO in complex 2e.
Table 2. ν(CO) Data for trans-[RhCl(CO)(L)2] Complexesa
[RhCl(CO)L2]
ν(CO)/cm-1
Figure 5. Thermal ellipsoid plot of 1h 2CH2Cl2 without the
2a
2b
2c
2d
2e
2f
1997
1994
1998
1997
1996
2008
1988
1965
2016
3
cocrystallized CH2Cl2 molecules. Displacement ellipsoids are
shown at the 50% probability level, and all solvent and hydro-
gen atoms have been removed for clarity. Selected bond lengths
˚
(A) and angles (deg): Pt1-P1, 2.2447(19); Pt1-P2, 2.2395(19);
L = CgPPhb
L = PPh3
L = P(OPh)3
Pt1-Cl1, 2.3421(19); Pt1-Cl2, 2.3583(19); P1-C2, 1.869(8);
P1-C9, 1.897(8); P1-O4, 1.597(5); C2-P1-C9, 94.5(3); P1-
Pt1-Cl1, 90.35(7); P2-Pt-Cl2, 90.59(7); P1-Pt1-P2, 94.06(7).
b
b
a In CH2Cl2. b From ref 18.
in 1h found in its solid-state structure is apparently different from
the solution structure, where, according to the 31P NMR
spectrum (δ 81.7, JPtP=3986 Hz; 77.7, JPtP=4162 Hz), the
P atoms are equivalent in both rac- and meso-1h. However a
variable-temperature 31P NMR study of 1h in CH2Cl2 re-
vealed that the singlets for the rac and meso isomers broaden,
and at -80 °C, one of the signals is resolved into two broad
signals (δ 83.7 and 77.2, w1/2 ca. 120 Hz, JPtP and JPP not
resolved) and the other is a broad singlet (δ 74.5, w1/2 ca. 40 Hz,
JPtP=4356 Hz). This behavior is consistent with the chelate ring
in the isomers of 1h adopting an unsymmetrical conformation
in solution such as that in the solid-state structure of rac-1h with
rapid ring inversion rendering the P atoms equivalent on the
NMR time scale at ambient temperatures; this fluxionality is a
consequence of the flexibility of the nine-membered ring in 1h.
Rhodium(I) Complexes. The complexes trans-[RhCl(CO)-
(CgPOR)2] (2a-f) were prepared according to eq 2 and
characterized by a combination of 31P, 13C NMR and IR
spectroscopy (see Experimental Section for the data). Once
again, the 31P NMR spectra for 2a-f showed two signals in ca.
1:1 ratio for the rac and meso diastereomeric products. The 13C
signals for the coordinated CO in complexes 2a-f are particu-
larly characteristic; in each case two overlapping doublets of
triplets are well-resolved, as exemplified in Figure 6 for 2e.
Table 2 that the phosphinites CgPOR are significantly better
π-acceptor ligands than the corresponding CgPPh. The
ν(CO) seems rather insensitive to the OR substituent since
the values for 2a-e fall in the narrow range 1994-1998
cm-1. Therefore it is notable that the value for 2f (2008 cm-1
)
is significantly different from the rest and approaches
that for [RhCl(CO){P(OPh)3}2]. Thus CgPOCH2CF3
(Lf) is the most triaryl phosphite-like of the CgPOR ligands
reported here, and this is consistent with Lf being the
most efficient monodentate CgPOR for hydrocyanation
(Table 1).
Roodt et al.29 have shown that the ν(CO) values for
trans-[RhCl(CO)(PX3)2] can be correlated with ν(CO) values
for [Ni(CO)3)(PX3)], and therefore a Tolman electronic
parameter (χ) can be estimated for the PCg substituent.
The ν(CO) values in Table 2 for 2a-e correspond to a
ν(CO) range of 2081-2084 cm-1 for the hypothetical
[Ni(CO)3(CgPOR)] complexes, from which a 2χ value for
the CgP substituent of 17 can be inferred, a similar value to
that calculated for a P(OMe)(OPh) group.4
Nickel(0) Complexes. The protocol for the hydrocyana-
tion catalysis involved generation of the catalyst in situ by
treatment of [Ni(cod)2] with the ligand (see Experimental
Section). In order to probe the nickel(0) chemistry that
may be involved in the catalysis, Lh (1 or 2 equiv) was added
to a C6D5CD3 solution of [Ni(cod)2] to give a deep red
solution that was very air sensitive; the color of the solution
turned pale yellow upon even the briefest exposure to air.
The mixtures were examined by 31P NMR spectroscopy,
which revealed that several species had formed (see Experi-
mental Section for the data). It had been anticipated that
an equilibrium may be established involving mononuclear
species [Ni(cod)(Lh)] and [Ni(Lh)2], for which the signals
would be complicated by the Lh being a mixture of two
diastereoisomers. Crystals that formed from the reaction
mixture were investigated by X-ray crystallography and
were shown to be the unexpected binuclear complex
The ν(CO) values for 2a-f were obtained from their IR
spectra in CH2Cl2 and are listed in Table 2. It is clear from
(29) Roodt, A.; Otto, S.; Steyl, G. Coord. Chem. Rev. 2003, 245, 121.

980 Organometallics, Vol. 30, No. 5, 2011
Mikhel et al.
to hydrolysis. Some potentially useful ligand structure-hydr-
ocyanation activity relationships have emerged for the mono-
dentates CgPOR and bidentates CgPZPCg, and these will be
further explored in subsequent publications.
Experimental Section
Unless otherwise stated, all reactions were carried out under a
dry nitrogen atmosphere using standard Schlenk line techniques.
Dry N2-saturated solvents were collected from a Grubbs system31
˚
in flame- and vacuum-dried glassware. MeOH was dried over 3 A
molecular sieves and deoxygenated by N2 saturation. All ligands
were stored under nitrogen at room temperature. The complex
[PtCl2(cod)] was prepared by a literature method.32 All other
reagents were used as received from Aldrich, Strem, or Lancaster.
1H (500 or 300 MHz), 31P (202 or 121 MHz), 13C (125 or 75
MHz), 19F (470 or 282 MHz), and 195Pt (64 MHz) NMR spectra
were recorded on a Varian VNMR S500 or Jeol Eclipse 300,
respectively. Chemical shifts δ are in parts per million (ppm), and
coupling constants J are in Hz. Chemical shifts are to high
frequency of the following external references: Si(CH3)4 (for 1H
and 13C), 85% H3PO4 (for31P), CFCl3 (for 19F), andH2PtCl6 (for
195Pt). Infrared spectra were measured on a Perkin-Elmer 1600
Series FTIR. High-resolution mass spectra were recorded on a
Bruker Daltonics (Coventry, UK) Apex IV 7.0 T Fourier-trans-
form ion cyclotron resonance mass spectrometer using electro-
spray ionization by the Mass Spectrometry Service, University of
Bristol. Elemental analyses were carried out by the Microanaly-
ticalLaboratory ofthe School of Chemistry, University of Bristol.
CgPBr. This was made by a modification of the literature
method.19 A CH2Cl2 solution of Br2 (30 mL, 0.73M, 22 mmol)
was added dropwise over 30 min to a cooled solution of CgPH
(4.324 g, 20.00 mol) in CH2Cl2 (60 mL) at 0 °C and stirred at this
temperature for 30 min. Then the ice bath was removed and the
reaction mixture was stirred for a further 1 h. The solvent was
evaporated off using a vacuum pump to give a light yellow solid
in near-quantitative yield. 31P NMR (CH2Cl2): δP 53.5. The
whole of the product thus obtained was used immediately in the
preparations of La-h below without further purification.
CgPOPh (La). A solution of BuLi in hexane (1.6 M, 12.5 mL,
20.00 mmol) was added dropwise to a solution of phenol (1.882
g, 20.00 mmol) in THF (20 mL) at 0 °C. The reaction mixture
was allowed to warm to ambient temperature and stirred for 1 h.
The obtained solution was slowly added over 30 min to a
solution of CgPBr (5.902 g, 20.00 mmol) in THF (60 mL) at
0 °C. After completing the addition, the ice bath was removed,
and the resulting suspension was stirred overnight. A solution of
crude ligand in CH2Cl2 was filtered through a short plug of silica
gel (3ꢀ2 cm) with CH2Cl2 as eluent and dried under reduced
pressure. The crude ligand was then purified by flash-chroma-
tography (CH2Cl2/pentane, 1:3 by volume) under pressure of
nitrogen and the product obtained as a white powder (4.336 g,
70%). Accurate mass spectrum: Mr 331.1082 (calcd for [M þ
Na]þ C16H21NaO4P 331.1070); Mr 309.1262 (calcd for [M þ H]þ
C16H22O4P 309.1250). Anal. Found (calcd for C16H21O4P): C,
62.54 (62.33); H, 6.87 (6.87). 31P NMR (CDCl3): δP 79.3. 13C
NMR (CDCl3): 157.8 (d, JCP=8.4, POCipso), 129.7 (s, Cpara),
122.9 (d, JCP = 1.3, Cmeta), 119.1 (d, JCP = 9.5, Cortho), 96.2
(d, JCP =1.2, CO), 95.9 (s, CO), 74.7 (d, 1JCP =26.3, PC), 73.3
(d, 1JCP =11.8, PC), 43.2 (d, JCP=17.9, CH2), 35.3 (s, CH2), 28.0
(s, CH3), 27.5 (d, JCP=1.0, CH3), 27.4 (d, JCP=22.7, CH3), 25.9
(d, JCP =12.8, CH3). 1H NMR (CDCl3): 7.30 (2H, t, JHH=8.1,
ArH), 7.11 (2H, d, JHH = 8.4, ArH), 7.05 (1H, t, JHH =7.5,
ArH), 2.28 (1H, d, JHH =13.4, CH2), 1.96 (1H, s, CH2), 1.91
(1H, d, JHP = 6.0, CH2), 1.64 (1H, dd, JHP=5.4, JHH=13.4,
Figure 7. Thermal ellipsoid plot of 3h 3C6H5CH3 without co-
3
crystallized toluene molecules. Displacement ellipsoids are
shown at the 50% probability level, and all solvent and hydro-
gen atoms have been removed for clarity. Selected bond
˚
lengths (A) and angles (deg): Ni-P1, 2.138(3); Ni-P2,
2.141(3); Ni-C30, 2.028(9); Ni-C31, 2.023(12); P1-C2,
1.864(11); P1-C9, 1.853(11); P1-O4, 1.664(7); C30-C31,
1.395(13); C2-P-C9, 91.9(5); P1-Ni-P2, 114.16(12);
P1-Ni-C31, 102.5(3); P2-Ni-C30, 102.8(3).
3h, containing a rare example30 of a bridging 1,5-cycloocta-
diene.
The crystals of 3h 3C7H8 that had grown in C6D5CD3
3
crystallized in space group P1; half of the molecule is
described by the asymmetric unit, with the other half gener-
ated by the inversion center lying at the center of the bridging
cyclooctadiene ligand. One and a half toluene solvent mole-
cules are also present in the asymmetric unit, with the half-
molecule on a center of inversion, such that when the symmetry
element of the space group is applied, three toluene molecules
are present in the unit cell. The structure (Figure 7) shows that
the meso isomer has crystallized with each diphosphinite
having both R- and β-enantiomer cages (P1 and P2, re-
spectively). The bite angle of the diphosphinite is 114.16°,
and the PO-xylyl moiety of the free Lh has undergone notable
changes; the P-O-C-C torsion angle is now 152.2(6)°/
145.8(8)°, and the O-CH2-xylyl-CH2-O backbone no
longer possesses the C2 symmetry that it had in free Lh.
In 3h the O-C-C-C torsion angles are -62.4(11)°
and -60.2(12)° for Ni1-P1-O4-C11 and Ni1-P2-
O8-C18, respectively (cf.-84.8° (both) in Lh).
One striking difference in the two chelate complexes of Lh is
in the P-M-P bite angles, which is 114° in 3h and 94° in 1h,
reflecting the flexibility of the nine-membered rings. A biden-
tate such as Lh that can accommodate angles between 90° and
120° (presumably atlowenergy cost) has potential advantages
for hydrocyanation catalysis10 because the accepted catalytic
cycle27 involves nickel species with trigonal, square, tetrahe-
dral, and trigonal bipyramidal coordination geometries.
Conclusions
The cage phosphinites are a new class of ligands for nickel(0)-
catalyzed hydrocyanation of the challenging 3-PN substrate,
which is an intermediate in the commercialized 1,3-butadiene
hydrocyanation. The CgPOR ligands have coordination prop-
erties akin to phosphites but have the advantage of resistance
(31) Pangborn, A. B.; Giardello, M. A.; Grubbs, R. H.; Rosen, R. K.;
Timmers, F. J. Organometallics 1996, 15, 1518.
(32) McDermott, J. X.; White, J.; Whitesides, G. M. J. Am. Chem.
Soc. 1976, 98, 6521.
(30) (a) Schaub, T.; Radius, U. Chem.;Eur. J. 2005, 11, 5024. (b)
Takei, I.; Wakebe, Y.; Suzuki, K.; Enta, Y.; Suzuki, T.; Mizobe, Y.; Masanobu
Hidai, M. Organometallics 2003, 22, 4639.

Article
Organometallics, Vol. 30, No. 5, 2011 981
CH2), 1.47 (3H, s, CH3), 1.41 (3H, s, CH3), 1.45 (3H, d, JHP
13.4, CH3), 1.41 (3H, d, JHP=13.8, CH3).
=
temperature and stirred for 1 h. The obtained solution was
slowly added over 30 min to the solution of CgPBr (5.902 g,
20.00 mmol) in THF (60 mL) at 0 °C. After completing the
addition, the ice bath was removed, and the resulting suspension
was stirred overnight. The solution was evaporated and the
obtained yellow solid was dried under reduced pressure. Then
the crude ligand was dissolved in CH2Cl2 (60 mL) and H2O (50
mL) was added. The aqueous phase was extracted once with
CH2Cl2 (50 mL). The combined organic phases were dried over
Na2SO4, the salt was removed by filtration, and the solution was
evaporated. The crude ligand was then purified by flash-chro-
matography (CH2Cl2/pentane, 1:3 by volume) under pressure of
nitrogen and the product obtained as a white solid (6.243 g,
74%). Accurate mass spectrum: Mr 443.2342 (calcd for [M þ
Na]þ C24H37NaO4P 443.2322); Mr 421.2521 (calcd for [M þ H]þ
C24H38O4P 421.2502). 31P NMR (CDCl3): δP 68.8. 13C NMR
(CDCl3): 154.0 (d, JCP = 7.3, POCipso), 143.9 (d, JCP = 1.2,
Carom), 124.5 (s, Carom), 123.5 (d, JCP =2.7, Carom), 138.0 (d,
CgPO(2-MeC6H5) (Lb). A solution of BuLi in hexane (1.6 M,
12.5 mL, 20.00 mmol) was added dropwise to a solution of
2-methylphenol (2.163 g, 20.00 mmol) in THF (20 mL) at 0 °C.
The reaction mixture was allowed to warm to ambient tempera-
ture and stirred for 1 h. The obtained solution was slowly added
over 30 min to the solution of CgPBr (5.902 g, 20.00 mmol) in
THF (60 mL) at 0 °C. After completing the addition, the ice bath
was removed, and the resulting suspension was stirred overnight.
The solution was evaporated, and the obtained yellow solid was
dried under reduced pressure. Then the crude ligand was dis-
solved in CH2Cl2 (60 mL) and H2O (50 mL) was added. The
aqueous phase was separatedand extracted once with CH2Cl2 (50
mL). The combined organic phases were dried over Na2SO4, the
salt was removed by filtration, and the solution was evaporated.
The crude ligand was then purified by flash-chromatography
(CH2Cl2/pentane, 1:3 by volume) under pressure of nitrogen and
the product obtained as a white powder (5.014 g, 78%). Accurate
mass spectrum: Mr 345.1236 (calcd for [M þ Na]þ C17H23NaO4P
345.1226); Mr 323.1418 (calcd for [M þ H]þ C17H24O4P
323.1407). Anal. Found (calcd for C17H23O4P): C, 63.73
(63.34); H, 7.16 (7.19). 31P NMR (CDCl3): δP 76.0. 13C NMR
(CDCl3): 155.9 (d, JCP=7.6, POCipso), 131.2 (s, Cpara), 128.3 (d,
J
CP=1.4, Carom), 115.5 (d, JCP=29.0, Cortho), 96.4 (d, JCP=1.1,
CO), 95.9 (s, CO), 75.1 (d, 1JCP=28.1, PC), 73.5 (d, 1JCP=11.4,
PC), 43.7 (d, JCP=18.2, CH2), 36.4 (s, CH2), 35.2 (s, C(CH3)3),
34.5 (s, C(CH3)3), 31.8 (s, C(CH3)3), 30.3 (s, C(CH3)3), 28.1 (s,
CH3), 27.6 (d, JCP=1.0, CH3), 27.9 (d, JCP=22.5, CH3), 26.4 (d,
J
J
J
CP=12.4, CH3). 1H NMR (CDCl3): 7.53 (1H, dd, JHH=8.7,
HP =6.0, ArH), 7.36 (1H, d, JHH =2.4, ArH), 7.18 (1H, dd,
HH =8.4, JHH=2.4, ArH), 2.40 (1H, d, JHH=13.2, CH2), 2.03
J
CP=1.9, Cortho), 127.0 (d, JCP=1.1, Cmeta), 122.3 (d, JCP=1.3,
meta), 116.9(d, JCP=18.4, Cortho), 96.2(d, JCP=1.1, CO), 95.9(s,
CO), 74.8 (d, 1JCP=27.5, PC), 73.3 (d, 1JCP=10.5, PC), 43.2 (d,
CP=17.7, CH2), 35.6 (s, CH2), 28.1 (s, CH3), 27.5 (d, JCP=1.1,
CH3), 27.4 (d, JCP=22.6, CH3), 26.1 (d, JCP=12.7, CH3), 16.7 (s,
C
(1H, dd, JHP=8.7, JHH=13.5, CH2), 1.92 (1H, dd, JHP=24.6,
JHH= 13.5, CH2), 1.69 (1H, dd, JHP=5.1, JHH=13.2, CH2),
1.46 (9H, s, C(CH3)3), 1.45 (3H, s, CH3), 1.44 (3H, s, CH3), 1.44
(3H, d, JHP=13.0, CH3), 1.41 (3H, d, JHP=12.9, CH3), 1.33 (9H, s,
C(CH3)3).
J
1
C
orthoCH3). H NMR (CDCl3): 7.24-7.12 (3H, m, ArH), 6.94
(1H, dt, JHH=7.2, JH,H=1.2, ArH), 2.31 (1H, d, JHH=13.2,
CH2), 1.95 (1H, d, JHH=13.5, CH2), 1.86 (1H, d, JHH=13.5,
CH2), 1.65 (1H, dd, JHP =5.4, JHH =13.2, CH2), 2.27 (3H, s,
CgPOMe (Le). A solution of BuLi in hexane (1.6 M, 12.5 mL,
20.00 mmol) was added dropwise to a solution of methanol
(0.577 g, 18.00 mmol) in THF (20 mL) at 0 °C. The reaction
mixture was allowed to warm to ambient temperature and
stirred for 1 h. The obtained solution was slowly added over
30 min to the solution of CgPBr (5.902 g, 20.00 mmol) in THF
(60 mL) at 0 °C. After completing the addition, the ice bath was
removed, and the resulting suspension was stirred overnight.
The solution was evaporated, and the obtained yellow solid was
dried under reduced pressure. Then the crude ligand was
dissolved in CH2Cl2 (60 mL) and H2O (50 mL) was added.
The aqueous phase was separated and extracted once with
CH2Cl2 (50 mL). The combined organic phases were dried over
Na2SO4, the salt was removed by filtration, and the solution was
evaporated. The crude ligand was then purified by flash-chro-
matography (CH2Cl2/pentane, 1:3 by volume) under pressure of
nitrogen and the product obtained as a white powder (3.110 g,
70%). Accurate mass spectrum: Mr 269.0926 (calcd for [M þ
CaromCH3), 1.46 (3H, s, CH3), 1.41 (3H, s, CH3), 1.42 (3H, d,
JHP=13.2, CH3), 1.41 (3H, d, JHP=12.9, CH3).
CgPO(2,4,6-Me3C6H2) (Lc). A solution of BuLi in hexane
(1.6 M, 12.5 mL, 20.00 mmol) was added dropwise to a solution
of 2,4,6-trimethylphenol (2.724 g, 20.00 mmol) in THF (20 mL)
at 0 °C. The reaction mixture was allowed to warm to ambient
temperature and stirred for 1 h. The obtained solution was
slowly added over 30 min to the solution of CgPBr (5.902 g,
20.00 mmol) in THF (60 mL) at 0 °C. After completing the
addition, the ice bath was removed, and the resulting suspension
was stirred overnight. The solution was evaporated and the
obtained yellow solid was dried under reduced pressure. Then
the crude ligand was dissolved in CH2Cl2 (60 mL) and H2O (50
mL) was added. The aqueous phase was separated and extracted
once with CH2Cl2 (50 mL). The combined organic phases were
dried over Na2SO4, the salt was removed by filtration, and the
solution was evaporated. The crude ligand was then purified by
flash-chromatography (CH2Cl2/pentane, 1:3 by volume) under
pressure of nitrogen and the product obtained as a white powder
(4.211 g, 60%). Accurate mass spectrum: Mr 373.1552 (calcd for
[M þ Na]þ C19H27NaO4P 373.1539); Mr 351.1733 (calcd for
[M þ H]þ C19H28O4P 351.1720). 31P NMR (CDCl3): δP 81.4.
13C NMR (CDCl3): 151.0 (d, JCP = 2.9, POCipso), 132.4 (s,
Cpara), 130.0 (s, Cmeta), 128.6 (d, JCP=2.0, Cortho), 96.0 (s, CO),
95.8 (s, CO), 75.3 (d, 1JCP=36.2, PC), 73.5 (d, 1JCP=9.8, PC),
43.0 (d, JCP=17.6, CH2), 35.2 (s, CH2), 28.0 (s, CH3), 27.4 (s,
CH3), 27.0 (d, JCP=21.5, CH3), 26.1 (d, JCP=13.7, CH3), 20.5 (s,
Na]þ C11H19NaO4P 269.0913). 31P NMR (CDCl3): δP 87.8. 13
C
NMR (CDCl3): 95.9 (s, CO), 95.7 (s, CO), 74.5 (d, 1JCP=25.4,
PC), 72.9 (d, 1JCP=10.7, PC), 59.1 (d, JCP=20.5, POCH3), 42.9
(d, JCP=16.6, CH2), 34.9 (s, CH2), 27.8 (s, CH3), 27.4 (s, CH3),
27.2 (d, JCP=23.5, CH3), 25.4 (d, JCP=13.7, CH3). 1H NMR
(CDCl3): 3.64 (3H, d, JHP=12.5, POCH3), 2.02 (1H, d, JHH
13.5, CH2), 1.83 (1H, d, JHH=13.5, CH2), 1.77 (1H, d, JHH
=
=
13.5, CH2), 1.48 (1H, dd, JHP=5.0, JHH=13.0, CH2), 1.37 (3H,
s, CH3), 1.35 (3H, d, JHP=12.5, CH3), 1.33 (3H, s, CH3), 1.32
(3H, d, JHP=13.5, CH3).
CgPOCH2CF3 (Lf). A solution of BuLi in hexane (1.6 M, 12.5
mL, 20.00 mmol) was added dropwise to a solution of trifluoro-
ethanol (2.001 g, 20.00 mmol) in THF (20 mL) at 0 °C. The
reaction mixture was allowed to warm to ambient temperature
and stirred for 1 h. The obtained solution was slowly added over
30 min to the solution of CgPBr (5.902 g, 20.00 mmol) in THF
(60 mL) at 0 °C. After completing the addition, the ice bath was
removed, and the resulting suspension was stirred overnight.
The solution was evaporated and the obtained yellow solid was
dried under reduced pressure. The crude ligand was then
purified by flash-chromatography (CH2Cl2/pentane, 1:3 by
1
CparaCH3), 18.2 (d, JCP =7.8, CorthoCH3). H NMR (CDCl3):
6.78 (2H, s, ArH), 2.41 (1H, d, JHH=13.0, CH2), 1.87 (1H, dd,
JHP=8.0, JHH 13.5, CH2), 1.77 (1H, dd, JHP=23.5, JHH=13.5,
CH2), 1.60 (1H, dd, JHP =5.5, JHH =13.0, CH2), 2.35 (6H, s,
CaromCH3), 2.22 (3H, s,CaromCH3), 1.45 (3H, s,CH3), 1.37 (3H, s,
CH3), 1.49 (3H, d, JHP=12.5, CH3), 1.27 (3H, d, JHP=12.5, CH3).
CgPO(2,4-tBu2C6H3) (Ld). A solution of BuLi in hexane (1.6
M, 12.5 mL, 20.00 mmol) was added dropwise to a solution of
2,4-di-tert-butylphenol (4.125 g, 20.00 mmol) in THF (20 mL) at
0 °C. The reaction mixture was allowed to warm to ambient

982 Organometallics, Vol. 30, No. 5, 2011
Mikhel et al.
volume) under pressure of nitrogen and the product obtained as
a white powder (4.806 g, 77%). Accurate mass spectrum: Mr
(d, 1JCP=9.8, PC), 73.07 (d, 1JCP=9.7, PC) 71.06 (dd, JCP=21.0,
JCP=1.0, POCH2), 71.04 (dd, JCP=20.8, JCP=1.0, POCH2),
43.14 (d, JCP=17.4, CH2), 43.12 (d, JCP=17.3, CH2), 35.45 (s,
CH2), 35.42 (s, CH2), 28.0 (s, CH3), 27.5 (d, JCP=1.0, CH3), 27.04
337.0795 (calcd for [M þ Na]þ C12H18F3NaO4P 337.0787). 31
P
NMR (CDCl3): δP 97.2 (q, JPF=7.4 Hz). 19F NMR (CDCl3):
δF -75.1 (q, JFH ≈ JFP=7.3 Hz). 13C NMR (CDCl3): 123.5 (dq,
1JCF=279.0, JCP=6.8, CF3), 96.0 (d, JCP=1.0, CO), 95.8 (s,
CO), 74.6 (d, 1JCP=25.5, PC), 73.1 (d, 1JCP=9.7, PC), 68.4 (dq,
JCF=21.4, JCP=35.1, CH2CF3), 43.0 (d, JCP=17.3, CH2), 34.9
(s, CH2), 27.8 (s, CH3), 27.3 (s, CH3), 26.9 (d, JCP=22.3, CH3),
25.4 (d, JCP=12.7, CH3). 1H NMR (CDCl3): 4.25-4.01 (2H, m,
POCH2), 2.04 (1H, d, JHH=13.5, CH2), 1.87 (1H, d, JHH=2.4,
CH2), 1.82 (1H, d, JHH =2.4, CH2), 1.54 (1H, dd, JHP =5.4,
JHH=13.2, CH2), 1.39 (3H, s, CH3), 1.37 (3H, d, JHP=13.8,
CH3), 1.35 (3H, s, CH3), 1.35 (3H, d, JHP=13.8, CH3).
(d, JCP=22.7, CH3), 27.0 (d, JCP=22.8, CH3), 25.74 (d, JCP
=
13.2, CH3), 25.72 (d, JCP = 13.2, CH3). 1H NMR (CDCl3):
7.45-7.39 (2H, m, ArH), 7.35-7.29 (2H, m, ArH), 5.04-4.88
(4H, m, POCH2), 2.06 (1H, d, JHH=12.9, CH2), 2.05 (1H, d, JHH
=12.9, CH2), 1.85 (2H, s, CH2), 1.83 (1H, d, JHH=13.8, CH2),
1.76 (1H, d, JHH=13.8, CH2), 1.50 (1H, dd, JHP=5.1, JHH=13.2,
CH2), 1.49 (1H, dd, JHP =5.4, JHH =13.2, CH2), 1.40 (3H, s,
CH3), 1.39 (3H, s, CH3), 1.34 (6H, s, CH3), 1.27 (6H, d, JHP
=
13.2, CH3), 1.16 (3H, d, JHP=13.2, CH3), 1.13 (3H, d, JHP=13.2,
CH3). Colorless crystals of Lh suitable for X-ray analysis
were obtained from a CH2Cl2/EtOAc/hexane mixture by slow
evaporation.
1,10-(CgPO)2-2,20-biphenyl (Lg). A solution of BuLi in hexane
(1.6 M, 12.5 mL, 20.00 mmol) was added dropwise to a solution
of 2,20-biphenol (1.862 g, 10.00 mmol) in THF (20 mL) at 0 °C.
The reaction mixture was allowed to warm to ambient tempera-
ture and stirred for 1 h. The obtained solution was slowly added
over 30 min to the solution of CgPBr (5.902 g, 20.00 mol) in THF
(60 mL) at 0 °C. After completing the addition, the ice bath was
removed, and the resulting suspension was stirred overnight.
The solution was evaporated and the obtained yellow solid was
dried under reduced pressure. Then the crude ligand was
dissolved in CH2Cl2 (60 mL) and H2O (50 mL) was added.
The aqueous phase was separated and extracted once with
CH2Cl2 (50 mL). The combined organic phases were dried over
Na2SO4, the salt was removed by filtration, and the solution
was evaporated. The crude ligand was then purified by crystal-
lization from a CH2Cl2/pentane mixture (1:5 by volume) and
the product obtained as a white powder (2.999 g, 49%). Accu-
rate mass spectrum: Mr 637.2094 (calcd for [M þ Na]þ
C32H40NaO8P2 637.2091). 31P NMR (CDCl3): δP 82.0 (96%,
broad), 79.0 (4%, broad). 13C NMR (CDCl3): 155.2 (d, JCP 7.9,
POCarom), 131.8 (s, Carom), 129.8 (s, Carom), 129.0 (s, Carom),
122.3 (s, Carom), 118.3 (d, JCP=14.7, Carom), 95.9 (s, CO), 95.7 (s,
CO), 74.6 (d, 1JCP=26.4, PC), 73.1 (d, 1JCP=10.8, PC), 43.1 (d,
Procedure for Catalytic Hydrocyanation of 3-Pentenenitrile.
Caution: Acetone cyanhydrin is a highly toxic liquid! It was used
only in a well-ventilated fume hood or a drybox and by teams of
at least two technically qualified persons who had received
appropriate training for treating HCN poisoning. HCN moni-
tors and proper first aid equipment were available. Excess
acetone cyanhydrin was disposed by slowly adding to aqueous
basic sodium hypochloride. All manipulations were performed
in an inert atmosphere (argon)-filled glovebox (Jacomex). GC
analyses were performed using a Hewlett-Packard HP6890 gas
chromatograph with a 250 μm ꢀ 30 m capillary column. Under
an inert atmosphere, the catalyst precursor [Ni(cod)2] (138 mg,
0.500 mmol) ligand (monodentate: 1.00 mmol; bidentate: 0.500
mmol), 3-pentenenitrile (1.21 g, 15.0 mmol), and Lewis acid
(0.50 mmol for ZnCl2; 0.25 mmol for Ph2BOBPh2 and TIBAO)
were introduced successively into a 60 mL Schott glass tube
equipped with a septum stopper. The reaction mixture was
subsequently heated to 70 °C with agitation. Acetone cyanhy-
˚
drin (previously dried over 4 A molecular sieves) was fed to the
mixture by a pressure syringe with a throughput of 0.45 mL h-1
.
The addition was stopped after 3 h, and then the mixture was
cooled to ambient temperature, diluted with acetone, and
analyzed by gas phase chromatography.
J
CP=18.5, CH2), 34.7 (s, CH2), 27.5 (s, CH3), 27.4 (s, CH3), 26.6
(d, JCP = 22.5, CH3), 26.3 (d, JCP = 12.7, CH3). 1H NMR
(CDCl3): 7.33 (2H, dt, J = 1.5, JHH = 7.5, ArH), 7.29-7.24
(4H, m, ArH), 7.09 (2H, dt, J=1.0, JHH=7.5, ArH), 1.88 (1H, d,
Synthesis of trans-[PtCl2(La)2] (1a). To a solution of
[PtCl2(cod)] (0.0374 g, 0.100 mmol) in CH2Cl2 (3 mL) was
slowly added ligand La (0.0617 g, 0.200 mmol) dissolved in
CH2Cl2 (3 mL) dropwise with stirring over ca. 10 min at ambient
temperature. The solution was stirred for an additional 2 days at
the same temperature, and the solvent was evaporated up to ca.
1 mL. The crude product was then purified by flash-chroma-
tography under pressure of nitrogen (Rf=0.3, Et2O/pentane, 1:5
by volume) to give complex 1a as a white-yellow powder (0.057
g, 65%). Accurate mass spectrum: Mr 904.1300 (calcd for [M þ
Na]þ C32H42Cl2NaO8P2Pt 904.1272). 31P NMR (CD2Cl2): δP
74.1 (1JPPt = 2852 Hz), 74.0 (1JPPt = 2852 Hz). 195Pt NMR
(CD2Cl2): δPt -3787.4 (t, 1JPtP=2847 Hz). 13C NMR (CD2Cl2):
154.0 (t, JCP=2.9, Carom), 129.2 (s, Carom), 123.6 (s, Carom), 119.7
(t, JCP=3.0, Carom), 119.67 (t, JCP=3.0, Carom), 96.0 (s, CO),
95.9 (s, CO), 76.92 (t, 1JCP=13.7, PC), 76.9 (t, 1JCP=13.7, PC),
JHH=14.0, CH2), 1.84 (1H, d, JHH=13.5, CH2), 1.86 (1H, d,
JHH=13.5, CH2), 1.80 (1H, d, JHH=13.5, CH2), 1.63 (2H, d,
JHH=13.0, CH2), 1.17 (2H, dd, JHP=5.0, JHH=13.0, CH2), 1.32
(6H, s, CH3), 1.29 (6H, s, CH3), 1.44 (6H, d, JHP=12.5, CH3),
0.87 (6H, d, JHP=13.0, CH3).
1,2-(CgPOCH2)2C6H4 (Lh). A solution of BuLi in hexane (1.6
M, 12 mL, 19.20 mmol) was added dropwise to a solution of 1,2-
benzenedimethanol (1.271 g, 9.199 mmol) in THF (50 mL) at
0 °C. Thereaction mixturewas allowed towarmtoambienttemp-
erature and stirred for 1 h. The obtained suspension was slowly
added over 30 min to the solution of CgPBr (5.902 g, 20.00 mmol)
in THF (60 mL) at 0 °C. After completing the addition, the ice
bath was removed, and the resulting suspension was stirred
overnight. The solution was evaporated, and the obtained yellow
solidwas driedunderreduced pressure. Thenthe crudeligandwas
dissolved in CH2Cl2 (60 mL) and H2O (50 mL) was added. The
aqueous phase was separatedand extracted once with CH2Cl2 (50
mL). The combined organic phases were dried over Na2SO4, the
salt was removed by filtration, and the solution was evaporated.
The crude ligand was then purified by flash-chromatography
(EtOAc/hexane, 1:6 by volume) under pressure of nitrogen and
the product obtained as a white powder (3.874 g, 74%). Accurate
mass spectrum: Mr 589.2110 (calcd for [M þ Na]þ C28H40-
NaO8P2 589.2091). Anal. Found (calcd for C28H40O8P2): C,
59.50 (59.36); H, 7.12 (7.12). 31P NMR (CDCl3): δP 86.0, 85.9.
76.31 (t, 1JCP=19.5, PC), 76.3 (t, 1JCP=19.1, PC), 43.0 (t, JCP
=
4.9, CH2), 42.95 (t, JCP=4.9, CH2), 39.7 (s, CH2), 27.3 (s, CH3),
26.90 (s, CH3), 26.72 (t, JCP=2.9, CH3), 26.68 (t, JCP=3.0, CH3),
1
25.12 (s, CH3), 25.1 (s, CH3). H NMR (CD2Cl2): 7.56-7.53
(4H, m, ArH), 7.37 (4H, t, JHH=7.5, ArH), 7.15 (2H, t, JHH=
7.5, ArH), 3.02 (1H, dt, JHH=14.0, JHP=2.5, CH2), 2.99 (1H, dt,
HH=14.0, JHP=2.5, CH2), 2.45 (1H, d, JHH=13.5, CH2), 2.448
J
(1H, d, JHH=13.5, CH2), 1.94 (0.5H, d, JHH=14.0, CH2), 1.92
(0.5H, d, JHH=14.0, CH2), 1.88 (0.5H, d, JHH=14.5, CH2), 1.87
(0.5H, d, JHH=14.0, CH2), 1.79-1.71 (2H, m, CH2), 1.650 (3H,
t, JHP=7.0, CH3), 1.647 (3H, t, JHP =7.0, CH3), 1.61 (3H, t,
JHP=7.0, CH3), 1.57 (3H, t, JHP=7.0, CH3), 1.43 (6H, s, CH3),
1.41 (3H, s, CH3), 1.39 (3H, s, CH3). White-yellow crystals of 1a
complex suitable for X-ray analysis were obtained from a
CH2Cl2/EtOAc mixture by slow evaporation.
13C NMR (CDCl3): 136.6 (d, JCP=5.6, POCH2C), 136.5 (d, JCP
=
5.7, POCH2C), 129.0 (s, Carom), 128.9 (s, Carom), 128.43 (s, Carom),
128.38 (s, Carom), 96.0 (t, JCP = 1.0, CO), 95.8 (d, JCP = 0.9,
CO), 74.7 (d, 1JCP=26.0, PC), 74.6 (d, 1JCP=25.8, PC), 73.08

Article
Synthesis of trans-[PtCl2(Le)2] (1e). To
Organometallics, Vol. 30, No. 5, 2011 983
a
solution of
27.4 (s, CH3), 27.3 (s, CH3), 26.64 (s, CH3), 26.55 (s, CH3), 26.4
(s, CH3), 25.7 (t, JCP=3.0, CH3), 24.4 (t, JCP=2.9, CH3). H
[PtCl2(NCtBu)2] (0.052 g, 0.13 mmol) in CH2Cl2 (2.5 mL)
was added dropwise CgPOMe (0.061 g, 0.25 mmol) in CH2Cl2
(2.5 mL) over 10 min. The resulting yellow solution was stirred
for 3 h. The solution was evaporated under reduced pressure to
ca. 1 cm3, and then Et2O (3.0 mL) was added to produce a yellow
solid precipitate, which was filtered off and washed with Et2O
(2 ꢀ 3 mL) to yield the product as a yellow powder (0.046 g,
50% yield). X-ray quality crystals of 1e were grown by the
slow diffusion of Et2O into its saturated CH2Cl2 solution. ESI
mass spectrum: Mr 723.14 (M - Cl). Anal: Found (calcd for
C22H38Cl2O8P2Pt) C, 35.43 (34.84), H, 4.99 (5.05). 31P NMR
(CDCl3): δp 83.4 (JPPt=2824 Hz). 13C NMR (CDCl3): 96.0 (s,
CO), 95.9(s, CO), 76.5 (t, 1JCP=14.67 Hz, PC), 58.1(t, 2JCP=6.85
Hz, OCH3), 42.9 (t, 2JCP=3.91 Hz, CH2), 39.7 (s, CH2), 27.6 (s,
CH3), 27.2 (s, CH3), 26.4, (t, 2JCP=2.96 Hz, CH3), 24.7 (s, CH3).
1H NMR (CDCl3): 4.04 (6H, t, JHP=6.1 Hz, CH3), 3.01 (2H, dt,
JHH=13.8, JHP=2.2 Hz, CH2), 2.3 (2H, d, JHH=13.4 Hz, CH2),
1.93-1.81 (2H, m), 1.72 (2H, d, JHH=13.6 Hz, CH2), 1.70-1.64
(12H, m, CH3), 1.42 (12H, s, CH3).
1
NMR (CDCl3): 7.45-7.39 (2H, m, ArH), 7.34-7.28 (2H, m,
ArH), 5.50 (1H, dd, JHP=5.5, JHH=11.0, POCH2), 5.31-5.27
(2H, m, POCH2), 5.11 (1H, dd, JHP=2.0, JHH=11.0, POCH2),
3.395 (0.5H, d, JHH =14.0, CH2), 3.39 (0.5H, d, JHH =14.0,
CH2), 3.38 (0.5H, d, JHH=14.0, CH2), 2.36 (1.5H, d, JHH=14.0,
CH2), 2.20 (1H, d, JHH = 13.5, CH2), 1.93 (0.5H, d, JHH
14.0, CH2), 1.89 (0.5H, d, JHH=14.0, CH2), 1.83 (0.5H, d, JHH
=
=
14.0, CH2), 1.78 (1H, d, JHH=14.0, CH2), 1.74 (0.5H, d, JHH=13.5,
CH2), 1.73 (0.5H, d, JHH=14.0, CH2), 1.71 (0.5H, d, JHH ≈ 14.0,
CH2), 1.68 (1.5H, d, JHP=14.5, CH3), 1.66 (1.5H, d, JHP=15.5,
CH3), 1.63 (4.5H, d, JHP=15.2, CH3), 1.50 (4.5H, s, CH3), 1.40
(4.5H, s, CH3), 1.39 (4.5H, s, CH3), 1.38 (1.5H, s, CH3), 1.36 (1.5H,
s, CH3). Colorless crystals of 1h complex suitable for X-ray analysis
were obtained from a CH2Cl2/EtOAc mixture by slow evaporation.
Synthesis of Rh(I) Complexes (general procedure). To a solu-
tion of [Rh2Cl2(CO)4] (0.100 mmol (0.0389 g) or 0.0500 mmol
(0.0194 g)) in CH2Cl2 (2 mL) was slowly added the correspond-
ing ligand (0.400 or 0.200 mmol) dissolved in CH2Cl2 (2 mL)
dropwise over 10 min with stirring at ambient temperature. The
resulting solution was stirred for an additional 2 h and then
filtered with CH2Cl2 (2 mL) used to rinse the filter. The clear
solution thus obtained was evaporated, and the product complex
was dried under reduced pressure. Yields were near-quantitative.
trans-[RhCl(CO)(La)2] (2a): yellow-brown powder. Accurate
mass spectrum: Mr 805.0941 (calcd for [M þ Na]þ C33H42-
ClNaO9P2Rh 805.0940). Anal. Found (calcd for C33H42ClO9P2-
Rh): C, 50.88 (50.62); H, 5.50 (5.41). IR (CH2Cl2): 1997 cm-1
ν(CO). 31P NMR (CD2Cl2): δP 104.9 (d, 1JPRh=143 Hz), 104.8
(d, 1JPRh=143 Hz). 13C NMR (CD2Cl2): 184.3 (dt, 1JCRh=70.5,
JCP=16.6, RhCO), 154.6 (t, JCP=1.9, Carom), 154.5 (t, JCP=1.9,
Synthesis of trans-[PtCl2(Lf)2] (1f). To a solution of [PtCl2-
(cod)] (0.0748 g, 0.200 mmol) in CH2Cl2 (5 mL) was slowly
added ligand Lf (0.1257 g, 0.400 mmol) dissolved in CH2Cl2 (5
mL) dropwise with stirring over ca. 10 min at ambient tempera-
ture. The solution was stirred for an additional 2 h at the same
temperature, and then the solvent was evaporated up to ca.
1 mL. The crude product was purified by flash-chromatography
under pressure of nitrogen (Rf = 0.15, Et2O/pentane, 1:10 by
volume) to give complex 1f as white-yellow powder (0.137 g,
76%). Accurate mass spectrum: Mr 916.0705 (calcd for [M þ
Na]þ C24H36Cl2F6NaO8P2Pt 916.0707). 31P NMR (CD2Cl2): δP
84.41 (1JPPt =2822 Hz), 84.38 (1JPPt =2822 Hz). 195Pt NMR
(CD2Cl2): δPt -3806.4 (t, 1JPtP=2821 Hz), -3808.9 (t, 1JPtP
2819 Hz). 19F NMR (CD2Cl2): δF -74.8 (m, JFH=8.9 Hz). 13
=
C
C
arom), 129.1 (s, Carom), 123.6 (s, Carom), 123.5 (s, Carom), 120.1
(t, JCP=3.9, Carom), 96.2 (s, CO), 95.9 (s, CO), 95.8 (s, CO), 76.7
(dt, JCRh=2.0, 1JCP=11.8, PC), 76.6 (dt, JCRh=2.0, 1JCP=9.7,
PC), 74.6 (dt, JCRh=1.9, 1JCP=13.7, PC), 74.5 (dt, JCRh=1.9,
1JCP =13.7, PC), 43.6 (t, JCP =5.9, CH2), 43.55 (t, JCP =5.9,
CH2), 37.9 (s, CH2), 37.8 (s, CH2), 27.4 (t, JCP=4.9, CH3), 27.35
(s, CH3), 27.3 (s, CH3), 27.2 (t, JCP=3.9, CH3), 26.95 (s, CH3),
26.9 (s, CH3), 25.3 (s, CH3), 25.2 (s, CH3). 1H NMR (CD2Cl2):
7.46-7.42 (4H, m, ArH), 7.38-7.30 (4H, m, ArH), 7.16-7.10
(2H, m, ArH), 2.80 (1H, dt, JHH=13.5, JHP=3.0, CH2), 2.70
(1H, dt, JHH=13.5, JHP=3.0, CH2), 2.383 (1H, d, JHH=13.5,
CH2), 2.38 (1H, d, JHH=13.5, CH2), 1.99 (0.5H, d, JHH=14.0,
CH2), 1.93 (0.5H, d, JHH=13.5, CH2), 1.95 (0.5H, d, JHH=14.0,
CH2), 1.89 (0.5H, d, JHH=14.0, CH2), 1.85-1.79 (2H, m, CH2),
1.70 (3H, t, JHP=6.5, CH3), 1.68 (3H, t, JHP=6.5, CH3), 1.50
(3H, t, JHP=7.0, CH3), 1.46 (6H, s, CH3), 1.45 (3H, t, JHP=7.0,
CH3), 1.38 (3H, s, CH3), 1.35 (3H, s, CH3).
trans-[RhCl(CO)(Lb)2] (2b): yellow-brown powder. Accurate
mass spectrum: Mr 833.1233 (calcd for [M þ Na]þ C35H46-
ClNaO9P2Rh 833.1253). Anal. Found (calcd for C35H46ClO9P2-
Rh): C, 51.80 (51.83); H, 5.73 (5.72). IR (CH2Cl2): 1994 cm-1
ν(CO). 31P NMR (CD2Cl2): δP 104.6 (d, 1JPRh=143 Hz), 104.3
(d, 1JPRh=143 Hz). 13C NMR (CD2Cl2): 184.4 (dt, 1JCRh=71.4,
JCP=15.6, RhCO), 184.3 (dt, 1JCRh=71.4, JCP=15.7, RhCO),
152.9 (t, JCP = 2.0, Carom), 152.8 (t, JCP = 1.8, Carom), 131.0
(s, Carom), 130.9 (s, Carom), 123.5 (s, Carom), 129.0 (t, JCP=2.0,
Carom), 128.99 (t, JCP =2.0, Carom), 125.9 (s, Carom), 125.8 (s,
NMR (CD2Cl2): 122.8 (qt, 1JCF=277.8, JCP=4.9, CF3), 96.0 (s,
CO), 76.66 (t, 1JCP=13.7, PC), 76.59 (t, 1JCP=13.7, PC), 76.32
(t, 1JCP=19.6, PC), 76.3 (t, 1JCP=18.6, PC), 66.6 (q, JCF=37.2,
POCH2), 43.15 (t, JCP=4.9, CH2), 43.08 (t, JCP=4.9, CH2), 39.5
(s, CH2), 27.2 (s, CH3), 26.8 (s, CH3), 25.67 (t, JCP=2.9, CH3),
25.62 (t, JCP=2.9, CH3), 24.44 (s, CH3), 24.4 (s, CH3). 1H NMR
(CD2Cl2): 4.76-4.68 (4H, m, POCH2), 2.92 (1H, dt, JHH=13.5,
JHP=2.5, CH2), 2.90 (1H, dt, JHH=14.0, JHP=2.5, CH2), 2.31
(2H, d, JHH=13.5, CH2), 1.96 (1H, d, JHH=14.0, CH2), 1.90
(1H, d, JHH=14.0, CH2), 1.73 (2H, dt, JHH=13.5, JHP=8.5,
CH2), 1.67 (6H, t, JHP=7.0, CH3), 1.65 (3H, t, JHP=7.5, CH3),
1.64 (3H, t, JHP=6.5, CH3), 1.39 (12H, s, CH3). White-yellow
crystals of 1f complex suitable for X-ray analysis were obtained
from a EtOAc/hexane mixture by slow evaporation.
Synthesis of cis-[PtCl2(Lh)] (1h). To a solution of [PtCl2(cod)]
(0.1871 g, 0.500 mmol) in CH2Cl2 (15 mL) was slowly added
ligand Lh (0.2833 g, 0.500 mmol) dissolved in CH2Cl2 (15 mL)
dropwise with stirring over ca. 20 min at ambient temperature.
The solution was stirred for an additional 2 h at the same
temperature, and the solvent was evaporated up to ca. 2 mL.
The complex was precipitated with pentane. The product thus
obtained was washed three times with small amounts of ether
and pentane and dried in air and then under vacuum to give
complex 1h as a white powder (0.306 g, 74%). Accurate mass
spectrum: Mr 854.1107 (calcd for [M þ Na]þ C28H40Cl2NaO8
P2Pt 854.1115). 31P NMR (CD2Cl2): δP 81.2 (1JPPt=3999 Hz),
76.6 (1JPPt = 4187 Hz). 195Pt NMR (CD2Cl2): δPt -4289.0
C
arom), 123.22 (s, Carom), 123.17 (s, Carom), 119.0 (t, JCP=3.9,
Carom), 118.9 (t, JCP=4.9, Carom), 96.21 (s, CO), 96.2 (s, CO),
95.88 (s, CO), 95.84 (s, CO), 95.8 (s, CO), 76.9 (dt, JCRh=2.0,
1
1
(t, JPtP =3999 Hz), -4252.3 (t, JPtP =4188 Hz). 13C NMR
(CD2Cl2): 135.5 (t, JCP=2.0, Carom), 135.0 (t, JCP=3.9, Carom),
130.4 (s, Carom), 129.5 (s, Carom), 129.0 (s, Carom), 128.8 (s,
Carom), 96.9 (s, CO), 96.5 (s, CO), 96.2 (s, CO) 96.0 (s, CO), 77.95
(dd, 1JCP=38.1, JCP=2.0, PC), 77.9 (dd, 1JCP=41.1, JCP=2.9,
PC), 77.1 (dd, 1JCP=25.4, JCP=3.9, PC), 77.0 (dd, 1JCP=29.3,
JCP =2.0, PC), 72.4 (t, JCP=5.8, POCH2), 72.3 (t, JCP=5.9,
1
1JCP =10.8, PC), 76.8 (dt, JCRh =2.0, JCP =10.7, PC), 74.6
(dt, JCRh=2.0, 1JCP=14.6, PC), 74.4 (dt, JCRh=2.9, 1JCP=14.7,
PC), 43.55 (t, JCP=6.8, CH2), 43.53 (t, JCP=5.9, CH2), 38.0 (s,
CH2), 37.9 (s, CH2), 27.6 (t, JCP=3.9, CH3), 27.5 (t, JCP=4.0,
CH3), 27.45 (s, CH3), 27.43 (s, CH3), 27.0 (s, CH3), 26.9 (s, CH3),
25.6 (s, CH3), 25.5 (s, CH3), 16.3 (s, CaromCH3), 16.2 (s,
POCH2), 70.1 (t, JCP=4.9, POCH2), 42.1 (s, CH2), 41.6 (t, JCP=
3.9, CH2), 41.4 (s, CH2), 40.4 (t, JCP=3.9, CH2), 27.5 (s, CH3),
C
aromCH3). 1H NMR (CD2Cl2): 7.72 (1H, d, JHH=8.0, ArH),
7.68 (1H, d, JHH=8.0, ArH), 7.24 (1H, dt, JHH=8.0, JHH=1.5,

984 Organometallics, Vol. 30, No. 5, 2011
Mikhel et al.
ArH), 7.21-7.18 (2H, m, ArH), 7.16 (1H, dt, JHH=8.0, JHH=1.5,
ArH), 7.06-7.00 (2H, m, ArH), 2.84 (1H, dt, JHH = 13.5,
JHP =2.5, CH2), 2.73 (1H, dt, JHH =13.5, JHP =3.0, CH2), 2.38
(2H, d, JHH =13.5, CH2), 2.00 (0.5H, d, JHH =14.0, CH2), 1.94
(0.5H, d, JHH=14.0, CH2), 1.96 (0.5H, d, JHH=14.0, CH2), 1.90
(0.5H, d, JHH=14.0, CH2), 1.88-1.82 (2H, m, CH2), 2.31 (3H, s,
CaromCH3),2.30(3H,s,CaromCH3), 1.72 (3H, t, JHP=7.0, CH3), 1.70
(d, JCP=7.8, POCH3), 43.7 (t, JCP=5.8, CH2), 37.4, CH2), 27.3
(s, CH3), 27.0 (s, CH3), 26.9 (s, CH3), 26.7 (t, JCP=3.9, CH3),
=
25.1 (t, JCP=1.9, CH3). 1H NMR (CD2Cl2): 3.90 (3H, t, JHP
6.0, POCH3), 3.88 (3H, t, JHP=6.5, POCH3), 2.66 (1H, dt, JHH
=
14.0, JHP=3.0, CH2), 2.58 (1H, dt, JHH=13.5, JHP=3.0, CH2),
2.26 (1H, d, JHH=13.5, CH2), 2.25 (1H, d, JHH=13.0, CH2),
1.91 (1H, d, JHH=14.0, CH2), 1.85 (1H, d, JHH=14.0, CH2),
1.79-1.74 (2H, m, CH2), 1.59 (3H, t, JHP = 6.5, CH3), 1.58
(3H, t, JHP=6.0, CH3), 1.52 (3H, t, JHP=7.0, CH3), 1.50 (3H,
t, JHP =7.0, CH3), 1.40 (6H, s, CH3), 1.36 (3H, s, CH3), 1.35
(3H, s, CH3).
(3H,t,JHP=7.0, CH3), 1.58 (3H, t, JHP=7.0, CH3), 1.53 (3H, t, JHP
=
7.0, CH3), 1.47 (6H, s, CH3), 1.41 (3H, s, CH3), 1.38 (3H, s, CH3).
Synthesis of trans-[RhCl(CO)(Lc)2] (2c). CgPOMes (0.036 g,
0.10 mmol) and [Rh2Cl2(CO)4] (0.010 g, 0.025 mmol) were
placed in an NMR tube. Upon the dropwise addition of CH2Cl2
(0.6 mL), evolution of CO gas was observed. When efferves-
cence had ceased, the solvent was removed under reduced
pressure to yield the product as a yellow-brown powder. ESI
mass spectrum: Mr 831.2 (M - Cl), 889.2 (M þ Na). Accurate
mass spectrum: Mr 889.1879 (calcd for [M þ Na]þ C39H54-
ClNaO9P2Rh 889.1884). Anal. Found (calcd for C39H54ClO9P2-
Rh): C, 53.84 (54.02); H, 6.34 (6.28). IR (CH2Cl2): 1998 cm-1
ν(CO). 31P NMR (CDCl3): 111.6 (d, 1JPRh=143 Hz), 109.7 (d,
1JPRh=143 Hz). 13C NMR (CDCl3): 149.0 (t, JCP=3.9, Carom),
132.5 (s, Carom), 129.0 (s, Carom), 127.9 (s, Carom), 94.95 (s, CO),
94.86 (s, CO), 94.76 (s, CO), 77.6 (dt, JCP=7.8, JCRh=1.9, PC),
43.3(t, JCP=4.9, CH2), 37.0(s, CH2), 28.7(t, JCP=3.9,CH3), 26.8
(s, CH3), 26.4 (t, JCP=3.9, CH3), 25.9 (s, CH3), 25.5 (s, CH3), 19.5
(s, CH3), 18.8 (s, CH3). 1H NMR (CDCl3): 6.73 (4H,s, ArH), 2.89
(2H, d, JHH=13.4, CH2), 2.58 (2H, d, JHH=13.4, CH2), 2.52
(12H, s, Arom CH3), 2.22 (2H, m, CH2), 2.20 (6H, s, Arom CH3),
1.93-1.82 (4H, m, CH2), 1.79 (6H, t, JHP=6.1, CH3), 1.55 (6H, t,
JHP=6.4, CH3), 1.48 (6H, s, CH3), 1.33 (6H, s, CH3).
trans-[RhCl(CO)(CgPOCH2CF3)2] (2f): yellow-green pow-
der. Accurate mass spectrum: Mr 817.0397 (calcd for [M þ
Na]þ C25H36ClF6NaO9P2Rh 817.0376). Anal. Found (calcd for
C25H36ClF6O9P2Rh): C, 38.07 (37.78); H, 4.61 (4.57). IR
(CH2Cl2): 2008 cm-1 ν(CO). 31P NMR (CD2Cl2): δP 116.4 (d,
1JPRh=140 Hz), 115.9 (d, 1JPRh=140 Hz). 19F NMR (CD2Cl2):
δF -74.79 (t, JFH=8.9 Hz), -74.84 (t, JFH=8.9 Hz). 13C NMR
(CD2Cl2): 183.9 (dt, 1JCRh=70.4, JCP=16.6, RhCO), 183.88 (dt,
1JCRh=71.4, JCP=15.7, RhCO), 122.5 (qt, 1JCF=277.8, JCP
=
3.9, CF3), 95.5 (s, CO), 95.4 (s, CO), 95.2 (s, CO), 75.8 (dt, JCRh
≈ 1.9, 1JCP=11.7, PC), 75.6 (dt, JCRh=1.9, 1JCP=10.8, PC), 73.3
(dt, JCRh=2.9, 1JCP=15.6, PC), 73.2 (dt, JCRh=3.0, 1JCP=14.6,
PC), 66.9 (dq, JCF=36.2, JCP=11.7, POCH2), 43.5 (t, JCP=6.3,
CH2), 36.3 (s, CH2), 26.44 (s, CH3), 26.4 (s, CH3), 26.15 (s, CH3),
26.1 (s, CH3), 25.1 (t, JCP=4.9, CH3), 24.4 (s, CH3). 1H NMR
(CD2Cl2): 4.75-4.66 (2H, m, POCH2), 4.42-4.32 (2H, m,
POCH2), 2.50 (1H, dt, JHH=14.0, JHP=3.0, CH2), 2.40 (1H,
dt, JHH=13.5, JHP=3.0, CH2), 2.175 (1H, d, JHH=13.5, CH2),
2.17 (1H, d, JHH=13.5, CH2), 1.89 (1H, d, JHH=14.5, CH2),
1.83 (1H, d, JHH =14.5, CH2), 1.75-1.69 (2H, m, CH2), 1.51
(3H, t, JHP=6.5, CH3), 1.50 (3H, t, JHP=6.5, CH3), 1.41 (3H, t,
trans-[RhCl(CO)(Ld)2] (2d): yellow-brown powder. Accurate
mass spectrum: Mr 1029.3459 (calcd for [M þ Na]þ C49H74-
ClNaO9P2Rh 1029.3444). Anal. Found (calcd for C49H74ClO9-
P2Rh): C, 58.17 (58.42); H, 7.24 (7.40). IR (CH2Cl2): 1997 cm-1
ν(CO). 31P NMR (CD2Cl2): 102.6 (d, 1JPRh=140 Hz), 101.7 (d,
JHP=7.0, CH3), 1.39 (3H, t, JHP=7.0, CH3), 1.32 (6H, s, CH3),
1.28 (3H, s, CH3), 1.27 (3H, s, CH3).
Reaction of Lh with [Ni(cod)2]. To a mixture of [Ni(cod)2]
(0.0275 g, 0.100 mmol) and ligand Lh (0.0567 g, 0.100 mmol) was
added C6D5CD3 (1.5 mL). The resulting mixture was stirred for
1 h and then the solution transferred to a Youngs NMR tube.
Red crystals of 3h suitable for X-ray crystallography deposited.
31P NMR (C6D5CD3): δP 126.0, 124.1 (2 singlets, 1:1 ratio,
intensity 70%); 123.6, 123.0 (2 singlets, 1:1 ratio, intensity 10%);
110 (broad, w1/2 = 100 Hz, intensity 10%). Under the same
conditions but using 2 equiv of Lh (0.1133 g, 0.200 mmol) the
spectrum obtained was very complicated with many signals in
the range 85-125 ppm.
1
1JPRh=142 Hz). 13C NMR (CD2Cl2): 185.2 (dt, JCRh=72.4,
J
CP=15.7, RhCO), 184.9 (dt, 1JCRh=71.4, JCP=15.6, RhCO),
150.5 (t, JCP=1.9, Carom), 150.46 (t, JCP=2.0, Carom), 150.0 (s,
arom), 144.9 (s, Carom), 138.3 (s, Carom), 138.2 (s, Carom), 124.5
C
(s, Carom), 124.3 (s, Carom), 122.0 (s, Carom), 119.1 (t, JCP=6.8,
Carom), 118.8 (t, JCP=6.8, Carom), 96.14 (s, CO), 96.0 (s, CO),
95.98 (s, CO), 76.7 (t, 1JCP=12.8, PC), 76.5 (t, 1JCP=11.7, PC),
75.1 (t, 1JCP=13.7, PC), 74.7 (dt, JCRh=2.9, 1JCP=12.7, PC),
44.2 (t, JCP=6.9, CH2), 44.0 (t, JCP=5.8, CH2), 38.0 (s, CH2),
37.8 (s, CH2), 34.93 (s, C(CH3)3), 34.92 (s, C(CH3)3), 31.3 (s,
C(CH3)3), 31.26 (s, C(CH3)3), 29.9 (s, C(CH3)3), 29.84 (s,
C(CH3)3), 28.5 (t, JCP=3.9, CH3), 28.4 (t, JCP=3.9, CH3), 27.2
(s, CH3), 27.1 (s, CH3), 27.0 (s, CH3), 26.2 (s, CH3), 26.1 (s, CH3).
1H NMR (CD2Cl2): 8.06 (1H, d, JHH=8.5, ArH), 8.00 (1H, d,
Crystal Structure Determinations. X-ray diffraction experi-
ments were carried out at 100 K on a Bruker Kappa Apex II
˚
CCD diffractometer, using Mo KR radiation (λ=0.71073 A). A
single crystal was coated in inert oil and mounted on a glass
fiber. Intensities were integrated33 from several series of expo-
sures in j and ω calculated by the Apex II34 program after unit
cell determination. Absorption corrections were based on
equivalent reflections using SADABS,35 and structures were
JHH=8.5, ArH), 7.39 (1H, d, JHH=2.5, ArH), 7.38 (1H, d, JHH
2.5, ArH), 7.23 (1H, dd, JHH=8.0, JHH=2.5, ArH), 7.14 (1H,
=
dd, JHH=8.5, JHH=2.5, ArH), 2.87 (2H, dt, JHH=13.0, JHP
3.0, CH2), 2.38 (1H, d, JHH=15.0, CH2), 2.35 (1H, d, JHH
=
=
2
refined against all Fo data with hydrogen atoms riding in
13.5, CH2), 2.07 (0.5H, d, JHH = 14.5, CH2), 2.01 (0.5H, d,
HH=14.5, CH2), 2.02 (0.5H, d, JHH=14.0, CH2), 1.97 (0.5H,
d, JHH=14.5, CH2), 1.86-1.80 (2H, m, CH2), 1.78 (3H, t, JHP
calculated positions using SHELXTL.36 Crystal structure and
refinement data are given in Table S1 (see Supporting In-
formation). Data for crystals 1e and 1f were twinned. The
different components of the non-merohedral twins were as-
signed using the Bruker program CELL_NOW37 and corrected
for absorption with TWINABS.38 Both of these structures have
J
=
6.5, CH3), 1.71 (3H, t, JHP=6.5, CH3), 1.62 (3H, t, JHP=7.0,
CH3), 1.60 (3H, t, JHP=7.0, CH3), 1.47 (9H, s, C(CH3)3), 1.46
(9H, s, C(CH3)3), 1.36 (9H, s, C(CH3)3), 1.35 (9H, s, C(CH3)3),
1.45 (3H, s, CH3), 1.42 (3H, s, CH3), 1.41 (3H, s, CH3), 1.39
(3H, s, CH3).
trans-[RhCl(CO)(Le)2] (2e): yellow-brown powder. Accurate
mass spectrum: Mr 681.0639 (calcd for [M þ Na]þ C23H38-
ClNaO9P2Rh 681.0627). IR (CH2Cl2): 1996 cm-1 ν(CO). 31P
(33) SAINT v7.34A; Bruker-AXS, 2007.
(34) Apex2; Bruker-AXS, 2007.
(35) Sheldrick, G. M. SADABS V2008/1; Bruker AXS Inc.: Madison,
WI, USA, 2008.
(36) SHELXTL program system version V 6.14; Bruker AXS Inc.:
Madison, WI, USA, 2000-3.
(37) Sheldrick, G. M. CELL NOW v2008/2; Bruker AXS Inc.:
Madison, WI, USA, 2008.
1
NMR (CD2Cl2): δP 111.69 (d, JPRh = 140 Hz), 111.67 (d,
1JPRh=140 Hz). 13C NMR (CD2Cl2): 185.50 (dt, 1JCRh=72.3,
JCP=15.7, RhCO), 185.46 (dt, 1JCRh=71.4, JCP=16.6, RhCO),
96.1 (s, CO), 96.0 (s, CO) 95.9 (s, CO), 76.0 (dt, JCRh=2.0, 1JCP
12.8, PC), 75.98 (dt, JCRh=2.0, 1JCP=11.7, PC), 73.9 (dt, JCRh
=
=
(38) Sheldrick, G. M. TWINABS v2008/2; Bruker AXS Inc.: Madison,
WI, USA, 2008.
2.0, 1JCP=14.7, PC), 73.8 (dt, JCRh=3.0, 1JCP=14.7, PC), 58.2

Article
Organometallics, Vol. 30, No. 5, 2011 985
incomplete data sets, as assignment of the non-merohedral
structure 3h C6H5CH3 exhibits static disorder, as the solvent
3
twinning occurred after data collection. The difference map
molecule lies on an inversion center. An occupancy of 50%
was assigned to the methyl substituent of the disordered
toluene molecule, and anisotropic displacement parameters
for the carbon were restrained to match the other chemically
similar carbon atom in the model.
-3
ꢁ
˚
ꢁ
˚
shows large features (ca. 4 e A ) close to (e1 A) the platinum
atom for 1e and 1h 2CH2Cl2, presumably due to absorption
effects and/or partial reflection overlaps due to twinning (1e
3
only) and unresolved data quality, but no features of chemical
significance. The data for 3h C6H5CH3 were hampered by loss
3
of the crystal before completion of the data collection to normal
levels (of completion). Attempts to collect further data from
other crystals proved fruitless due to crystal sensitivity and
disintegration. The partial data set was solved and refined de-
spite the poor completeness (58%), and refinement converged
smoothly to the residuals and geometry shown. To improve
the disordered dichloromethane solvent model for structure
Acknowledgment. We would like to thank Paul Gates
for mass spectrometry measurements, Craig Butts for
NMR measurements and discussion, Rhodia and EPSRC
for financial support, the CCDC for a studentship (to
C.L.M.), COST Action CM0802 “PhoSciNet”, and
Johnson-Matthey for loan of precious metal compounds.
1h 2CH2Cl2, the position of one chlorine atom was split using
a free variable and restrained to match other chemically
similar atoms. One of the cocrystallized toluene molecules in
3
Supporting Information Available: This material is available
free of charge via the Internet at http://pubs.acs.org.