Novel chelating phosphonite ligands: Syntheses, structures, and nickel-catalyzed hydrocyanation of olefins

Article abstract of DOI:10.1021/om701140c

A series of sterically tuned chelating bisarylphosphonite ligands with a cis-1,2-(bi)cycloalkane spacer and cyclic phosphonite moieties was synthesized. The spacer as well as the phosphacycles were modified to investigate their influence in the nickel-catalyzed hydrocyanation of styrene and 1,3-butadiene and the isomerization of 2-methyl-3-butenenitrile. NMR studies detect only catalytically active (P_∩P)Ni(COD) species and no hints of the formation of catalytically inactive dibisphosphonite complexes (P _∩P)₂Ni are found. In the hydrocyanation of styrene, these catalysts are highly active (93% conversion) and highly regioselective (99.9% iso) at moderate catalyst concentrations (1 mol %). They also proved to be very active in the hydrocyanation of butadiene with turnover numbers of 644 and turnover frequencies of 426 h^-1 at low catalyst concentrations (0.1 mol %). Moreover, they very efficiently catalyze the isomerization of 2-methyl-3-butenenitrile to the linear 3-pentenenitrile.

Full text of DOI:10.1021/om701140c

Organometallics 2008, 27, 2189–2200
2189
Novel Chelating Phosphonite Ligands: Syntheses, Structures, and
Nickel-Catalyzed Hydrocyanation of Olefins
Alexander P. V. Göthlich, Marcus Tensfeldt, Helmut Rothfuss, Michael E. Tauchert,
Dagmar Haap, Frank Rominger, and Peter Hofmann*
Organisch-Chemisches Institut, Ruprecht-Karls-UniVersität Heidelberg, Im Neuenheimer Feld 270,
D-69120 Heidelberg, Germany
ReceiVed NoVember 13, 2007
A series of sterically tuned chelating bisarylphosphonite ligands with a cis-1,2-(bi)cycloalkane spacer
and cyclic phosphonite moieties was synthesized. The spacer as well as the phosphacycles were modified
to investigate their influence in the nickel-catalyzed hydrocyanation of styrene and 1,3-butadiene and the
isomerization of 2-methyl-3-butenenitrile. NMR studies detect only catalytically active (P∩P)Ni(COD)
species and no hints of the formation of catalytically inactive dibisphosphonite complexes (P∩P)2Ni are
found. In the hydrocyanation of styrene, these catalysts are highly active (93% conversion) and highly
regioselective (99.9% iso) at moderate catalyst concentrations (1 mol %). They also proved to be very
active in the hydrocyanation of butadiene with turnover numbers of 644 and turnover frequencies of 426
h
-1 at low catalyst concentrations (0.1 mol %). Moreover, they very efficiently catalyze the isomerization
of 2-methyl-3-butenenitrile to the linear 3-pentenenitrile.
Scheme 1. Hydrocyanation of 1,3-Butadiene (DuPont Process)
Introduction
The nickel-catalyzed hydrocyanation of 1,3-butadiene is of
great technical interest, since the product adiponitrile is an
important building block for nylon-6.6 production. The technical
procedure, the so-called Du Pont ADN process, covers about
67% of the world’s demand of adiponitrile, which is estimated
to be 1.3 million tons per year.1 The reaction proceeds in three
steps, all of which are catalyzed by Ni(0)-phosphite complexes
(Scheme 1).
The first step always generates mixtures of the linear
3-pentenenitrile (3PN) and the branched 2-methyl-3-butenenitrile
(2M3BN), but only hydrocyanation of 3PN leadssafter in situ
isomerization via 4-pentenenitrile (4PN)sto the desired adi-
ponitrile (ADN).
2M3BN can be isomerized to 3PN, as the thermodynamic
equilibrium consists of a 93/7 (3PN/2M3BN) mixture.2 Until
recently a cascade of dehydrocyanation/rehydrocyanation has
been assumed as the mechanistic pathway on the basis of
deuterium-labeling experiments.3 More recent work, however,
proposes allylic species as reactive intermediates.4 For the
addition of the second HCN molecule a Lewis acid is necessary.5
One general problem in catalytic hydrocyanation is the
formation of insoluble and catalytically inactive nickel(II)
cyanides by excess HCN. Complexes with chelating ligands are
known to be much more stable with respect to catalyst poisoning
by excess HCN or air.6 Therefore, ligand design has focused
on bidentate ligands in recent years. Interestingly, it has been
noted that ligands designed for efficient rhodium-catalyzed
hydroformylation often also show good performance in nickel-
catalyzed hydrocyanation reactions.
As to the mechanism of 1,3-diene hydrocyanation using
phosphorus-based chelating ligands, not very much is known
about the details of the catalytic cycle(s) (Scheme 2). One can
assume that after addition of Ni(COD)2 as a Ni(0) source to a
solution of the ligands, complexes of type A are formed (Vide
infra). The reaction then proceeds either by oxidative addition
of HCN to the metal center, resulting in complexes B, followed
by η2-coordination of 1,3-butadiene or, in reverse order, first
substituting cyclooctadiene by a (presumably η2-bound) 1,3-
butadiene molecule yielding D, followed by oxidative addition
of HCN. Both pathways lead to intermediates C. Insertion of
the diene into the Ni-H bond generates the methallyl complexes
E, which are transformed to the cyano olefin complex isomers
F or G by reductive elimination. These complexes can reenter
the cycle with release of t3PN and 2M3BN, either via
oxidative addition of HCN leading back to B or via
substitution of the C5-nitriles by 1,3-butadiene, giving D. The
* To whom correspondence should be adressed. E-mail: ph@
oci.uni-heidelberg.de.
(1) Burridge, E. Eur. Chem. News 2005, 15,. 4-10. April.
(2) Tolman, C. A.; Mc Kinney, R. J.; Seidel, W. C.; Druliner, J. D.;
Stevens, W. R. AdV. Catal. 1985, 33, 1.
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Chaudret, B.; Barthelat, J.-C.; Galland, J.-C. Organometallics 2004, 23,
3363. (b) Wilting, J.; Müller, C.; Hewat, A. D.; Tooke, D. L.; Vogt, D.
Organometallics 2005, 24, 13. (c) Acosta-Ramírez, A.; Muñoz-Hernández,
M.; Jones, W. D.; García, J. J. J. Organomet. Chem. 2006, 691, 3895. (d)
Acosta-Ramírez, A.; Muñoz-Hernández, M.; Jones, W. D.; García, J. J.
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10.1021/om701140c CCC: $40.75
2008 American Chemical Society
Publication on Web 04/15/2008

2190 Organometallics, Vol. 27, No. 10, 2008
Göthlich et al.
Scheme 2. Proposed Catalytic Cycles for 1,3-Butadiene Hydro-
cyanation and Isomerization of 2M3BN
Scheme 3. A New Class of Chelating Trisaryl Bisphosphorus
Ligands for Rhodium-Catalyzed Hydroformylation Reactions
selective rhodium-catalyzed hydroformylation,10 has been also
successfully applied in the hydrocyanation of 1,3-butadiene by
Vogt et al.11
In the past few years carbohydrate-based bisphosphinites,12
Xantphos-type bisphosphonites,13 and phosphites using a BINOL
backbone14 have been employed with success for asymmetric
hydrocyanations of vinylarenes, cyclodienes, and substituted 1,3-
dienes.
For the isomerization of 2M3BN to 3PN a series of Xantphos-
type phosphines and phosphonites has been investigated,15 as
well as dppb,4a DPEphos,4b and dppf.4c
For the development of a new class of chelating ligands for
rhodium-catalyzed hydroformylation reactions, which model two
monodentate P-ligands in a predefined spatial arrangement at
the metal center, we have recently used a simple molecular
mechanics approach to tailor spacer units connecting two
triphenylphosphine, -phosphonite, or -phosphite moieties in a
well-defined and adjustable way. Mono- and bicyclic alkanes
that are cis-1,2-connected to the ortho-positions of phenyl rings
bound to two phosphorus atoms, which carry two more aryl
units, turned out to be suitable spacers16 (Scheme 3).
Molecular modeling suggested that for such ligands cis-
coordination in square-planar d8-ML4 complexes, which are part
of the catalytic cycle of hydroformylation as well as hydrocya-
nation, is favored. Moreover, simple cycloalkane spacers are
thermally and chemically inert. Due to the modular construction
of these systems, we were able to synthesize a variety of
bisphosphine ligands and metal derivatives (essentially bridged
versions of bis-triphenylphosphine complexes as in Scheme 3)
with different steric and electronic properties and to apply them
for rhodium-catalyzed hydroformylation.16
Ni-catalyzed 2M3BN/t3PN isomerization process involving
E, F, and G is part of the proposed mechanistic picture of
Scheme 2 as well, without specifying, however, if the E to
F + G transformation is accomplished by direct C-CN bond
forming via reductive elimination from E or by HCN
elimination/readdition through C.
In 1991 Pringle et al.6 reported the first chelate nickel(0) and
palladium(0) phosphite complexes derived from 2,2′-dihydroxy-
biphenyl, a system previously used in the rhodium-catalyzed
hydroformylation by UCC7 and by van Leeuwen et al.,8 and
the use of these systems in the hydrocyanation of 1,3-butadiene.
Since then, a series of bisphosphine, bisphosphonite, and
bisphosphite ligands, originally designed for rhodium-catalyzed
hydroformylation, has been successfully applied for the hydro-
cyanation of vinylarenes, of R-olefins, and of 1,3-dienes.
Especially Xantphos-type bisphosphines and bisphosphonites
have been studied in the latter reactions by Vogt and van
Leeuwen and co-workers.9 Most recently a triptycene-type
bisphosphine ligand, developed in our group for highly n-
Taking into account the above-mentioned structural relation-
ship and the similarities of ligands employed in hydroformy-
lation and hydrocyanation, we found it attractive to also
synthesize phosphonite derivatives corresponding to the phos-
phine ligands of Scheme 3. The phosphonite chelate systems
are more π-acidic than their bisphosphine analogues and are
likely to facilitate the rate-determining reductive elimination step
in the nickel-catalyzed hydrocyanation. Apart from their use in
(7) Billig, E.; Abatjoglou, A. G.; Bryant, D. R. (UCC) US Pat. 4.769.498,
1988.
(8) (a) van Rooy, A.; Kramer, P. C. J.; van Leeuwen, P. W. N. M.;
Goubitz, K.; Fraanje, J.; Veldmann, N.; Spek, A. L. Organometallics 1996,
15, 835. (b) van Rooy, A.; Orij, E. N.; Kramer, P. C. J.; van Leeuwen,
P. W. N. M. Organometallics 1995, 14, 34. (c) van Rooy, A.; de Bruijn,
J. N. H.; Roobeek, K. F.; Kramer, P. C. J.; van Leeuwen, P. W. N. M. J.
Organomet. Chem. 1996, 507, 69.
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R. WO 0158589, 2001. (b) Ahlers, W.; Paciello, R.; Vogt, D.; Hofmann,
P. WO 02083695 A1, 2002. (c) Warth, D. C. M. Diploma Thesis, University
of Heidelberg, 1999. (d) Warth, D. C. M. Dissertation, University of
Heidelberg, 2004. (e) Hofmann, P., Invited lecture, 14th International
Symposium on Homogeneous Catalysis, Munich, 2004, abstract IL7.
(11) Bini, L.; Müller, C.; Wilting, J.; von Chrzanowski, L.; Spek, A. L.;
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3081. (b) Kranenburg, M.; Kamer, P. C. J.; van Leeuwen, P. W. N. M.;
Chaudret, B. Chem. Commun. 1997, 373. (c) Kranenburg, M.; Delis, J. G. P.;
Kamer, P. C. J.; van Leeuwen, P. W. N. M.; Vrieze, K.; Spek, A. L.;
Goubitz, K.; Fraanje, J. J. Chem. Soc., Dalton Trans. 1997, 1839. (d) van
Leeuwen, P. W. N. M.; Sandee, A.; Reek, J.; Kamer, P. C. J. J. Mol. Catal.
A 2002, 182-183, 107. (e) van der Veen, L. A.; Kamer, P. C. J.; van
Leeuwen, P. W. N. M. Organometallics 1999, 18, 4765. (f) van der Vlugt,
J. L.; Sablong, R.; Magusin, P. C. M. M.; Mills, A. M.; Spek, A. L.; Vogt,
D. Organometallics 2004, 23, 3177. (g) Kranenburg, M.; Kamer, P. C. J.;
van Leeuwen, P. W. N. M.; Vogt, D.; Keim, W. Chem. Commun. 1995,
2177. (h) Goertz, W.; Kamer, P. C. J.; van Leeuwen, P. W. N. M.; Vogt,
D. Chem. Commun. 1997, 1521. (i) Goertz, W.; Keim, W.; Vogt, D.; Englert,
U.; Boele, M. D. K.; van der Veen, L. A.; Kamer, P. C. J.; van Leeuwen,
P. W. N. M. J. Chem. Soc., Dalton Trans. 1998, 2981.
(12) (a) Casalnuovo, A. L.; RajanBabu, T. V.; Ayers, T. A.; Warren,
T. H. J. Am. Chem. Soc. 1994, 116, 9869. (b) Saha, B.; RajanBabu, T. V.
Org. Lett. 2006, 8, 4657.
(13) Goertz, W.; Kamer, P. C. J.; van Leeuwen, P. W. N. M.; Vogt, D.
Chem.-Eur. J. 2001, 7, 8.
(14) (a) Wilting, J.; Janssen, M.; Müller, C.; Lutz, M.; Spek, A., L.;
Vogt, D. AdV. Synth. Catal. 2007, 349, 350. (b) Wilting, J.; Janssen, M.;
Müller, C.; Vogt, D. J. Am. Chem. Soc. 2006, 128, 11374.
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A. M.; Lutz, M.; Spek, A. L.; Vogt, D. AdV. Synth. Catal. 2004, 346, 993.
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(BASF AG) NAE 278/2000, 2000.

Nickel-Catalyzed Hydrocyanation of Olefins
Organometallics, Vol. 27, No. 10, 2008 2191
Scheme 4. Chelating Bisphosphonite Ligands 1 to 5 with a cis-1,2-Substituted Mono- or Bicyclic Spacer and Cyclic Phosphonite
Moieties
Scheme 5. Synthesis of Phosphonite Ligands
hydroformylation and hydrocyanation reactions, chelating phos-
phonite ligands have also been employed for asymmetric
hydrogenation reaction of ꢀ-ketoesters and ketones,17 quino-
lines,18 Suzuki cross-coupling reaction,19 and conjugated addi-
tion of arylboronic acids20 during the past few years.
We report here the syntheses and representative solid state
structures of the chelating bisphosphonite ligands 1 to 5 (Scheme
4) with a cis-1,2-substituted mono- or bicyclic spacer and cyclic
phosphonite moieties. Modifications of the spacer unit as well
as of the phosphacycles served to investigate the influence of
different steric properties of the metal complexes in catalysis.
The coordination behavior of the new ligands toward Ni(COD)2
was examined by NMR techniques, and the structure of a
monoligand Ni(0) complex, (2-κ2P)Ni(COD), was confirmed
by X-ray-diffraction.
easily converted into the phosphonite ligands by refluxing in
Using HCN, the performance of ligands 1-5 in the nickel-
the presence of 2 equiv of the appropriate dihydroxybiaryl
catalyzed hydrocyanation of 1,3-butadiene and styrene was
derivative17 in dry toluene (Scheme 5).
studied, as well as their ability to isomerize 2M3BN to 3PN.
2,2′-Dihydroxy-1,1′-biphenyl, racemic 2,2′-dihydroxy-1,1′-
The data obtained from our catalysis experiments make the new
binaphthyl, and bis(2-hydroxyphenyl)methane are commercially
ligands appear fully competitive with known systems from the
available, whereas the chloro precursors cis-1,2-bis(o-chlo-
literature.
rophenyl)cyclopentane and -hexane and endo-cis-2,3-bis(o-
chlorophenyl)norbornane had to be prepared as described below.
Results and Discussion
Takaya et al. have described the synthesis of enantiopure
trans-10.22 We modified the synthesis for the preparation of
cis-10 (Scheme 6). o-Chlorobenzaldehyde was condensed with
malonic acid in a Knoevenagel reaction. After decarboxylation,
the cinnamic acid derivative23 obtained was converted into the
methyl ester 6, which was then coupled24 with a second
molecule of the same compound in a radical reaction using a
sodium powder slurry in THF at 40 °C. After in situ Dieckmann
condensation the ꢀ-ketoester 7 was formed, which, after
Ligand Syntheses. The key step in the synthesis of all ligands
was the lithiation of the corresponding chloro compounds at
-78 °C using a lithium slurry in THF and the subsequent
phosphorylation21 with bis(diethylamino)chlorophosphane. A
sodium content of 0.5-0.8% of the lithium powder was essential
for this reaction. The amidophosphonites obtained could be
(17) (a) Reetz, M. T.; Li, X. AdV. Synth. Catal. 2006, 348, 1157. (b)
Reetz, M. T.; Li, X. J. Am. Chem. Soc. 2006, 128, 1044.
(18) Reetz, M. T.; Li, X. Chem. Commun. 2006, 2159.
(19) Punji, B.; Mague, J. T.; Balakrishna, M. S. Dalton Trans. 2006,
1322.
(22) Fukuda, N.; Mashima, K.; Matsumara, Y.; Takaya, H. Tetrahedron
Lett. 1990, 31, 7185.
(23) Jones, B.; Watkinson, J. G. J. Chem. Soc. 1958, 4064.
(24) (a) Totton, E. L.; Freeman, R. C.; Powell, H.; Yarboro, T. L. J.
Org. Chem. 1961, 26, 343. (b) Totton, E. L.; Klipatrick, G. R.; Horton, N.;
Blakeney, S. A. J. Org. Chem. 1965, 30, 1647.
(20) Reetz, M. T.; Moulin, D.; Gosberg, A. Org. Lett. 2001, 3, 4083.
(21) Goertz, W.; Kamer, P. C. J.; van Leeuwen, P. W. N. M.; Vogt, D.
Chem.-Eur. J. 2001, 7, 1614.

2192 Organometallics, Vol. 27, No. 10, 2008
Scheme 6. Synthesis of the Ligand Backbone 10
Göthlich et al.
Scheme 7. Synthesis of 15
separation of the cis- and trans-isomers with respect to the
relative configuration of the aryl groups, was decarboxylated
with hydrobromic acid.25 The resulting ketone 8 was then
reduced via transformation into the tosylhydrazone26 9 and
subsequent reduction with catechol borane.27 Direct Wolff–
Kishner reduction of 8 yielded only a cis/trans mixture of 10
as, under basic conditions, the stereocenters at the benzylic
carbons were racemized.
oxidation30 yielded the corresponding ketone rac-13, which was
transformed into rac-14 by nucleophilic addition of o-chlo-
rophenyllithium25 and elimination of water from the initially
formed alcohol with catalytic amounts of p-TsOH. Hydrogena-
tion using palladium/charcoal31 in petroleum ether provided a
2/1 mixture of cis- and trans-15, from which the cis-isomer
was easily separated by recrystallization from petroleum ether.
Precursor 21 was synthesized in a similar fashion (Scheme
8). As epoxide opening of norbornene oxide did not lead to the
desired product, 18 was prepared by Grignard addition of
o-chlorophenyl-Grignard to norcamphor, followed by elimina-
tion using p-TsOH and hydroboration using BH3 · oxathiane.26
The last part of the synthesis (PCC oxidation,26 nucleophilic
addition of o-chlorophenyllithium,25 elimination and hydrogena-
tion on Pd/charcoal27) was carried out in analogy with the
preparation of 15.
X-ray crystal structures of free 1, 3, 4, and 5 are shown in
Figures 1–4. Coordination to a single metal center is possible,
as both phosphorus atoms are oriented to the same side of the
spacer. The nonbonding P-P distances of 3.90 (1), 3.63 (3),
3.80 (4), and 3.93 Å (5) show that only little reorientation of
the backbone is necessary for coordination. All structures bear
the phosphacycles and the benzylic protons of the spacer in syn-
For the preparation of the cyclohexane derivative 15 (Scheme
7), we started from cyclohexene oxide, which was reacted with
o-chlorophenyl lithium28 in the presence of BF3-etherate to give
rac-12.29 Thorough cooling to -110 °C using liquid nitrogen/
pentane was essential to suppress aryne formation. PCC
(25) Totton, E. L.; Klipatrick, G. R.; Horton, N.; Blakeney, S. A. J.
Org. Chem. 1965, 30, 1647.
(26) (a) Caglioti, L. Org. Syn. 1960, 52, 122. (b) Hutchins, R. O.;
Milewski, C. A.; Maryanoff, B. E. J. Am. Chem. Soc. 1973, 95, 3662. (c)
Hutchins, R. O.; Kacher, M.; Rua, L. J. Org. Chem. 1975, 40, 923.
(27) (a) Kabalka, G. W.; Baker, J. D., Jr. J. Org. Chem. 1975, 40, 1834.
(b) Kabalka, G. W.; Yang, D. T. C.; Chandler, J. H.; Baker, J. D., Jr.
Synthesis 1977, 124.
(28) (a) Gilman, H.; Gorsich, R. D. J. Am. Chem. Soc. 1956, 78, 2217.
(b) Harder, S.; Brandsma, L.; Kanters, J. A.; Duisenberg, A.; van Lenthe,
J. H. J. Organomet. Chem. 1991, 420, 143.
(29) (a) Alexakis, A.; Vrancken, E.; Mangeney, P. Synlett 1998, 1165.
(b) Mizuno, M.; Kanai, M.; Iida, A.; Tomioka, K. Tetrahedron: Asymmetry
1996, 7, 2483. (c) Mizuno, M.; Kanai, M.; Iida, A.; Tomioka, K.
Tetrahedron 1997, 53, 10199.
(30) (a) Corey, E. J.; Suggs, J. W. Tetrahedron Lett. 1975, 31, 2647.
(b) Canelli, G.; Gardillo, G. Chromium Oxidations in Organic Chemistry,
Bd. 19, Springer Verlag: Berlin, 1984.
(31) Kindler, K.; Oelschläger, H.; Henrich, P. Chem. Ber. 1953, 86, 167.

Nickel-Catalyzed Hydrocyanation of Olefins
Organometallics, Vol. 27, No. 10, 2008 2193
Scheme 8. Synthesis of 21
arrangement. Comparison of 1 with 3 shows the different steric
bulk of the phosphacycles. The biphenyl moieties in 1, 4, and
Figure 3. ORTEP representation of 4. Thermal ellipsoids are drawn
at the 50% probability level; hydrogen atoms are omitted for clarity.
Figure 1. ORTEP representation of 1. Thermal ellipsoids are drawn
at the 50% probability level; hydrogen atoms are omitted for clarity.
Figure 4. ORTEP representation of 5. Thermal ellipsoids are drawn
at the 50% probability level; hydrogen atoms are omitted for clarity.
5 display S,R-configuration in the solid state. In solution fast
isomerization takes place, as the biaryl rotational barriers are
small.32
Nickel Complexes. Formation of the precatalysts by com-
plexation of the free ligands (1.05 equiv) with Ni(COD)2 was
investigated by solution NMR.
The formation of (P∩P)Ni(COD) type complexes is shown
in the 31P NMR spectrum by exclusive observation of clean
singlets for compounds 1 (196.0 ppm, toluene-d8), 3 (169.1 ppm,
benzene-d6), 4 (194.7 ppm, toluene-d8), and 5 (194.4 ppm,
toluene-d8) as well as by the chemical shift of the coordinated
1
COD in H NMR.
In (2-κ2P)Ni(COD) the P atoms are magnetically inequivalent,
and in the 31P NMR spectrum two doublets are observed at
193.7 and 200.2 ppm with a P-P coupling constant of 101.1
Hz in THF-d8. The exclusive formation of these monochelate
complexes is one reason for the high catalytic activity of these
Figure 2. ORTEP representation of 3. Thermal ellipsoids are
drawn at the 50% probability level; hydrogen atoms are omitted
for clarity.
(32) Whiteker, G. T.; Harrison, A. M.; Abatjoglou, A. G. J. Chem. Soc.,
Chem. Commun. 1995, 1805.

2194 Organometallics, Vol. 27, No. 10, 2008
Göthlich et al.
Scheme 9. Formation of (P∩P)Ni(COD) Species from
Ni(COD)2 and Free Phosphonite Ligands
ligands, as the concentration of the active species is not reduced
by formation of catalytically inactive bischelate complexes
(Scheme 9).
Complex (1-κ2P)Ni(COD) was isolated and fully character-
ized. Crystals suitable for X-ray crystal structure analysis of
complex (2-κ2P)Ni(COD) were obtained by isothermic distil-
lation of a solution in toluene under argon.
The molecular structure of (2-κ2P)Ni(COD) (Figure 5)
confirms that a monochelate is formed, as already concluded
from the NMR experiments described above. As expected, the
Ni(0) center shows a distorted tetrahedral geometry, as can be
seen from the P1-Ni-P2 angle of 101.7° and the Ct1-Ni-Ct2
angle of 89.0° (the centers of each COD double bond are defined
as centroids 1 and 2). The Ni-C distances (2.116-2.177 Å)
Figure 5. ORTEP representation of (2-κ2P)Ni(COD). Thermal
ellipsoids are drawn at 50% probability; hydrogen atoms are omitted
for clarity. Selected interatomic distances (Å) and angles (deg):
Ni1-P1 ) 2.1214(10), Ni1-P2 ) 2.1052(10), Ni1-C60 )
2.147(4), Ni1-C61 ) 2.177(4), Ni1-C64 ) 2.119(4), Ni1-C65
) 2.116(4), P2-Ni1-P1 ) 101.67(4), P1-Ni1-C60 ) 128.18(11),
P2-Ni1-C61 ) 128.82(11), P1-Ni1-C61 ) 97.83(11).
33
are slightly elongated compared to those in Ni(COD)2
(2.11-2.13 Å). The Ni-P bond lengths (2.121, 2.105 Å) are
slightly longer than in bis(tri-o-tolyl phosphite)Ni(η2-ethylene)34
(2.093-2.098 Å), but shorter than a typical Ni-PPh3 distance
of 2.224 Å,35 as expected from the different back-bonding
abilities of the ligands. In contrast to the molecular structures
of the free ligands 1, 3, 4, and 5, both P atoms show
S,S-configuration of the phosphacycle, which is conformationally
stable due to the bulky binaphthyl groups, which prevent
rotation. As a racemic mixture of the ligand is used, the crystal
contains a racemic mixture of both enantiomers.
Catalysis. In order to determine the potential of the new
phosphonite ligands, we applied them in the hydrocyanation of
styrene and 1,3-butadiene as well as in the isomerization of
2M3BN to 3PN. Although a very comfortable and easily
dispensable source of HCN in the form of acetone cyanohydrine
is described in the literature,6 we used free HCN for these
reactions, as preliminary results showed that the activity of the
catalysts was more than twice as high with HCN.
Information. In many cases the reactions were finished after 90
min and no further changes were observed; for those experi-
ments only data after 1.5 h are given.
Under the chosen conditions, 1 showed full conversion within
1.5 h. Regioselectivity was excellent with 99.9% of the branched
nitrile 2-phenylpropionitrile (2PPN) being produced. This can
be explained by the fact that intermediates of this reaction path
can be stabilized by η3-benzyl interaction.37 Insertion of styrene
into the Ni-H bond is reversible12 and leads to different isomers
(Scheme 10). After addition of HCN, the reaction mixture turns
from yellow to deep red, as the η3-benzyl intermediates are
intensely colored.
Application of 2 and 3, in which the phosphacycle has been
modified, resulted in a dramatic loss of activity to 16% and
30% conversion, respectively, and the regioselectivity drops to
83% and 95%, producing an increased amount of the linear
nitrile 3-PPN. Apparently the steric bulk of the phosphacycle
has a drastic impact on selectivity and reactivity. One possible
explanation is that due to steric hindrance, the bulky (ligand)-
Ni(CN)(η3-benzyl) complexes are disfavored as compared to
the smaller (ligand)Ni(CN)ethylphenyl complex.
To be able to compare our results to those with ligands
described in the literature, the standardized conditions described
by van Leeuwen and Vogt9g–i were used for the hydrocyanation
of styrene. For the hydrocyanation of butadiene and the
isomerization of 2M3BN, we slightly modified the conditions
described by Foo, Garner, and Tam (DuPont patent).36
Hydrocyanation of Styrene. Using reaction conditions
published by Vogt et al.9g–i the catalysts were prepared in a
Schlenk tube by reaction of the ligands with 1 equiv of
Ni(COD)2 in toluene at room temperature. After 20 min
preformation time 20 equiv of styrene and 25 equiv of HCN
were added at once, which corresponds to a catalyst concentra-
tion of 5 mol % (based on styrene), whereupon the Schlenk
tube was placed in a heating bath at 60 °C. Samples were taken
after 1.5, 3, and 16 h and analyzed by temperature-controlled
gas chromatography. Table 1 shows selected results. A more
complete list of the results obtained is available in the Supporting
Enlargement of the ring size (cyclohexane derivative 4) and
restriction of the flexibility (norbornane derivative 5) also lead
to a decrease of reactivity (60% vs 40%), whereas regioselec-
tivity remains nearly unaffected.
In order to investigate the potential of ligand 1 more closely,
we performed runs with lower catalyst loadings. One mol % of
Ni led to a conversion of 93% with consistently high regiose-
lectivity (99.9%). At 0.25 mol % the activity significantly
dropped to 16% conversion.
Compared to the Xantphos-based ligands used by Vogt et
al.9 our catalyst (1-κ2P)Ni(COD) showed, under identical
conditions, better performance (1 mol % 1, 93% conversion,
90 min vs 5 mol % CF3-C6H4-Xantphos, 90% conversion, 16 h).
The binaphthol-based bisphosphite ligands, published recently
by Vogt et al., under the same conditions achieved 100%
(33) Dierks, H.; Dietrich, H. Z. Kristallogr., Kristallgeometr., Kristall-
phys., Kristallchem. 1965, 122, 1.
(34) Guggenberger, L. J. Inorg. Chem. 1973, 12, 499.
(35) Allen, F. H.; Kennard, O.; Watson, D. G.; Brammer, L.; Orpen,
A. G.; Taylor, R. J. Chem. Soc. Perkin Trans. 2 1987, 1.
(36) (a) Foo, T.; Garner, J. M.; US Pat. 5,981,772, 1999. (b) Garner,
J. M.; Kruetzer, K. A.; Tam, W. WO 99/06358, 1999. (c) Garner, J. M.;
Kruetzer, K. A.; Tam, W. US Pat. 6,127,567, 2000. (d) Tam, W.; Foo, T.;
Garner, J. M. WO 99/52632, 1999.
(37) McKinney, R. J. In Homogeneous Catalysis; Parshall, G. W., Ed.;
Wiley: New York, 1992; p 42.

Nickel-Catalyzed Hydrocyanation of Olefins
Organometallics, Vol. 27, No. 10, 2008 2195
Table 1. Catalytic Hydrocyanation of Styrenea,b
ligand
time [h]
Ni [mol %]
yieldb [%]
2PPNb [%]
3PPNb [%]
regioselectivityb [%]
TONb
TOFb [h-1
]
1
1
1
2
2
3
3
4
4
5
5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
0.25
1.00
5.00
1.00
5.00
1.00
5.00
1.00
5.00
1.00
5.00
16
93
>99
20
28
3
17
26
51
17
34
16
93
99
19
27
3
14
26
51
17
33
0.02
0.05
0.07
0.96
1.40
0.44
3.02
0.09
0.18
0.45
0.83
99.9
99.9
99.9
95.3
95.0
85.0
82.3
99.7
99.6
97.4
97.6
64
92
20
20
6
3
3
26
10
17
7
43
61
13
14
4
2
2
18
7
12
5
a Reaction conditions: toluene (4 mL), ligand/metal ) 1.05, HCN/styrene ) 1.25, 60 °C, preformation time ) 20 min. b Yield, regioselectivity, and
TON determined by GC analysis. Regioselectivity ) yield 2PPN/total yield. All runs were doubled to ensure consistency.
Scheme 10. n- vs iso-Insertion of Styrene into Ni-H Bonds
isomerization activity had increased, as the n/iso ratio rose to
almost 8. This clearly shows that the catalyst was not poisoned.
These results are in good agreement with those from the
isomerization reaction described later.
The more flexible cyclopentane ligand 1 and the cyclohexane
derivative 4 turned out to be more active in the hydrocyanation
of butadiene. Both catalysts show almost complete conversion
within 90 min, with 1 being more n-selective (n/iso ) 1.8)
compared to 4 (n/iso ) 1.4). These highly active catalysts were
subjected to further optimization of the reaction conditions.
Hydrocyanation using ligand 1 was performed at lower tem-
peratures, which led to a drop of activity and selectivity: At 80
°C only 30% conversion after 1.5 h was monitored, rising to
87% after 3 h with lower n/iso ratios of 2. At 100 °C the reaction
stops after 1.5 h at 90% conversion with consistently low n/iso
ratios.
conversion after 4 h and an ee of 43%.38 However, this system
showed only moderate activity in the isomerization of 2M3BN.
The monodentate phosphite ligands P(O-p-tolyl)3 used industri-
ally showed only little activity.
Decreasing the catalyst concentrations to 0.1 mol % Ni for 1
and to 0.05 mol % for 4 reduces the activity significantly to
yield only 48% and 40% conversion. The optimum for 1 is
reached at 0.15 mol % with a TON of 493 and a TOF of 328
h-1. With a catalyst loading of 0.1 mol % Ni, however, 4 yielded
Hydrocyanation of 1,3-Butadiene. Ligands 1-5 were also
tested in the hydrocyanation of 1,3-butadiene. Typically, reac-
tions were carried out at 120 °C with an HCN/butadiene ratio
of approximately 0.75 using 0.2 mol % catalyst (based on
butadiene), prepared in situ from Ni(COD)2 and 1.05 equiv of
ligand. After 20 min preformation time, the catalyst solutions
were placed in a 10 mL glass autoclave and cooled to -78 °C.
1,3-Butadiene and HCN were transferred from a Schlenk tube
(also at -78 °C) via Teflon cannula through a ball valve into
the autoclave. The valve was closed and the autoclave placed
into a thermostated heating bath at 120 °C. After 1.5, 3, and
16 h samples were taken (after cooling of the autoclave to -30
°C) and analyzed by temperature-controlled gas chromatogra-
phy. Table 2 gives an overview of the hydrocyanation results
under these standardized conditions. An extended list of
experiments performed is provided in the Supporting Informa-
tion. The amount of nitriles other than t3PN and 2M3BN was
usually below 3%, and the only non-nitrile side product
monitored was 4-vinylcyclohexene.
Comparison of the three different ligand spacers shows that
the rigid norbornane derivative 5 has the smallest TONs.
Conversion of 75% and a TON of 294 were reached after 90
min, and the reaction stops at this level. As the mechanism
involves four- and five-coordinate species that are assumed to
be square-planar, tetrahedral, or trigonal-bipyramidal, the ligands
have to adapt to different chelating angles. Therefore, a rigid
backbone as in 5 seems to be unfavorable. Due to its steric
bulk, we expected this ligand to show higher n-selectivity, which
is, however, not the case after 3 h (n/iso ) 0.9). After 16 h
93% conversion and a TON of 638 and a TOF of 426 h-1
.
Under these conditions P(O-p-tolyl)3, described in a DuPont
patent for the technical hydrocyanation of butadiene (ligand/
metal ) 6.0),32 reached 9% conversion after 3 h. To investigate
the influence of the phosphacycle, we substituted the seven-
membered dibenzodioxaphosphepine group by the also seven-
membered, but bulkier dinaphthodioxaphosphepine group in 2
and an eight-membered dibenzodioxaphosphocinyl group in
ligand 3. The higher steric requirements of the naphthyl
substituents led to a significant loss of activity, as conversion
dropped to 60% after 90 min with nearly no n/iso selectivity.
In contrast, 3 turned out to be highly active, as it led to complete
conversion after 90 min with a moderate n/iso ratio of 2.0. As
observed in the case of ligand 5, isomerization activity then
began to increase the n/iso ratio to 9.2 after 16 h. Constant
lowering of the catalyst concentration revealed an optimum of
0.1 mol % with 92% conversion, n/iso ) 1.2, and a TON of
644.
Isomerization of 2M3BN. Isomerization of 2M3BN using
our ligands resulted in high selectivity for the desired 3PN. The
aim of this reaction is to accelerate the adjustment of the
thermodynamic ratio of 93/7 (3PN/2M3BN) in order to convert
the undesired 2M3BN into 3PN.
Ligands 1-5 performed very well in this reaction (Table 3,
complete list in the Supporting Information). In terms of activity,
we found the same trends that were determined in the hydro-
cyanation of butadiene with 1 and 4 turning out to be the most
efficient catalysts. Ligand 4 reached almost complete conversion
after 3 h, and 1 achieved, after 3 h, a level of 86%, rising to
(38) Wilting, J.; Janssen, M.; Müller, C.; Lutz, M.; Spek, A. L.; Vogt,
D. AdV. Synth. Catal. 2007, 349, 350.

2196 Organometallics, Vol. 27, No. 10, 2008
Göthlich et al.
Table 2. Catalytic Hydrocyanation of 1,3-Butadienea
ligand
time [h]
T [°C]
Ni [mol %]
yield [%]b
n/iso
2M3BN [%]
t3PN [%]
TON
TOF [h-1
]
1
1
1
1
1
1
1
2
2
2
3
3
3
3
3
3
4
4
4
4
4
4
5
5
5
1.5
3
16
1.5
1.5
3
16
1.5
3
16
1.5
3
16
1.5
3
16
1.5
3
16
1.5
3
16
1.5
3
120
120
120
120
80
0.20
0.20
0.20
0.10
0.20
0.20
0.20
0.20
0.20
0.20
0.20
0.20
0.20
0.10
0.10
0.10
0.20
0.20
0.20
0.05
0.05
0.05
0.20
0.20
0.20
0.20
0.20
0.20
0.20
0.20
0.20
85
98
99
48
30
54
87
63
60
78
98
98
98
86
92
94
91
87
92
38
35
40
75
73
74
7
1.8
2.0
2.1
4.3
1.9
2.0
2.0
0.8
1.3
0.6
2.0
5.0
9.2
0.7
1.2
3.5
0.9
0.9
2.0
1.4
1.4
1.4
0.9
0.9
7.9
1.7
1.8
1.8
1.4
1.5
1.6
30
32
30
9
11
18
27
34
26
47
32
16
9
49
41
18
48
45
29
16
14
15
39
37
7
53
63
64
38
19
36
56
27
32
28
65
80
86
35
49
71
40
39
58
21
19
20
33
34
62
4
302
347
343
323
108
194
305
233
222
288
318
316
312
605
644
640
325
312
323
551
499
531
294
287
285
22
202
116
21
215
72
65
19
156
74
18
212
105
20
403
215
40
217
104
20
368
166
33
196
96
18
14
10
80
80
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
16
1.5
3
16
1.5
3
c
c
c
d
d
d
P(O-p-tolyl)3
P(O-p-tolyl)3
P(O-p-tolyl)3
P(O-p-tolyl)3
P(O-p-tolyl)3
P(O-p-tolyl)3
2
3
4
1
1
1
9
13
2
3
6
5
7
1
1
30
36
5
7
2
3
2
1
16
2
8
a Reaction conditions: toluene (4 mL), ligand/metal ) 1.05, HCN/butadiene ≈ 0.75, preformation time ) 20 min. b Yield (based on HCN),
selectivity, TON, and TOF determined by GC analysis. c Ligand/metal ) 6. d Ligand/metal ) 2.1. All runs were doubled to ensure consistency.
Table 3. Catalytic Isomerization of 2M3BNa,b
ligand
t [h] T [°C] Ni [mol %] yield [%] 2M3BN [mol %] t3PN [mol %] n/iso selectivity t3PN [%] TON TOF [h-1
]
1
1
1
1
1
1
1
1
1
2
2
2
3
3
3
4
4
4
4
4
4
5
5
5
1.5
3
16
1.5
3
16
1.5
3
16
1.5
3
16
1.5
3
16
1.5
3
16
1.5
3
16
1.5
3
16
120
120
120
120
120
120
80
0.20
0.20
0.20
0.10
0.10
0.10
0.20
0.20
0.20
0.20
0.20
0.20
0.20
0.20
0.20
0.20
0.20
0.20
0.10
0.10
0.10
0.20
0.20
0.20
0.20
0.20
0.20
0.20
0.20
0.20
61
86
96
5
39
14
4
81
58
4
43
40
26
66
35
4
35
17
5
28
5
4
62
44
7
66
45
4
58
83
90
3
1.5
5.5
17.1
0.0
0.6
15.9
1.2
1.3
2.5
0.5
1.7
17.3
1.7
4.0
15.5
2.2
11.1
12.8
0.4
0.9
8.6
0.4
1.0
95
96
94
61
94
93
95
95
96
91
93
90
96
97
97
91
91
89
86
90
93
87
91
91
50
54
81
11
14
49
295
421
469
28
196
140
29
19
116
58
179
92
22
107
102
29
208
126
29
220
152
29
185
148
54
94
79
28
9
37
96
56
57
71
34
64
96
64
77
95
70
95
96
32
49
91
32
52
95
6
34
89
53
54
69
31
59
86
62
75
92
63
86
86
27
44
85
28
47
86
3
347
935
269
275
347
160
307
469
311
377
466
330
456
460
277
445
871
141
238
455
14
80
80
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
120
11.6
0.0
0.1
0.4
0.0
c
c
c
d
d
d
P(O-p-tolyl)3
P(O-p-tolyl)3
P(O-p-tolyl)3
P(O-p-tolyl)3
P(O-p-tolyl)3
P(O-p-tolyl)3
1.5
3
16
1.5
3
16
87
82
55
87
84
80
9
25
4
4
10
5
21
0
1
5
25
104
2
3
23
8
7
2
1
0.0
0.1
1
a Reaction conditions: toluene (4 mL), ligand/metal ) 1.05, preformation time ) 20 min, 2M3BN had a purity of 98.0% (1.3% t2M2BN, 0.3% t3PN,
determined by GC). b Yield (based on 2M3BN), selectivity, TON, and TOF determined by GC analysis. c Ligand/metal ) 6. d Ligand/metal ) 2.1. All
runs were doubled to ensure consistency.
96% after 16 h. Surprisingly, 3 turned out to be less active in
the isomerization of 2M3BN (77% conversion after 3 h),
probably due to the higher steric demands of the ligand. This
might also be the reason for the moderate activity of 2 (64%
conversion) with the bulky binaphthyl phosphacycle and 5 (52%
conversion) with the sterically demanding norbornane spacer

Nickel-Catalyzed Hydrocyanation of Olefins
Organometallics, Vol. 27, No. 10, 2008 2197
by Dr. Tottoli and are uncorrected. Detailed analytic data of the
compounds described may be found in the Supporting Information.
Hydrogenations were performed in a Teflon-coated Berghoff 100
mL autoclave, and hydrogen (99.9999%) was purchased from
Messer Griesheim. Hydrocyanations of butadiene were carried out
in a 10 mL glass autoclave (BASF AG) equipped with a Teflon-
coated stirring bar. HCN was generated by addition of H2SO4 to
potassium cyanide, the vapor stream was dried by passing a
Siccapent column, and HCN was frozen in a cooling trap.
after 3 h. In the latter case, high rigidity of the backbone might
also be a reason for the slow conversion, as adjustment of the
ligand to the different coordination geometries during the
reaction is hindered. Nevertheless it has to be pointed out that
all ligands yielded the thermodynamic equilibrium mixture after
16 h.
Reducing the temperature to 80 °C resulted in a loss of
activity; after 16 h only 71% conversion was achieved for ligand
1. Obviously, higher temperatures are essential for the reaction.
Reducing the catalyst concentration resulted in an optimum of
0.1 mol % for 1 and 4 to give complete conversion (16 h) and
TONs of 935 and 871, respectively.
To obtain directly comparable reference data, isomerization
was also carried out with P(O-p-tolyl)3 (ligand/metal ) 2.1 and
6.0), resulting in a maximum of 25% conversion (16 h, ligand/
metal ) 6.0), reproducing the figures reported in the DuPont
patent.32 The drastic difference between monodentate and
chelating ligands in terms of activity and selectivity is quite
remarkable. Using a wide range of Xantphos-type phosphonites
Vogt et al. achieved a maximum yield of 72% for 3PN using
catalyst concentrations of 2.5 mol % at 90 °C after 1 h.15 Acosta-
Ramírez et al. recently described the use of dppf in this reaction,
using 0.9 mol % catalyst, achieving 83% 3PN after 2.5 h at
100 °C.4c
Tosylhydrazone of cis-3,4-Bis(o-chlorophenyl)cyclopentanone
(9).22 A 250 mL flask with reflux condenser was charged with cis-
3,4-bis(o-chlorophenyl)cyclopentanone (8) (1.79 g, 5.9 mmol),
tosylhydrazine (1.63 g, 8.1 mmol), and 100 mL of dry methanol.
The mixture was heated to reflux for 6 h, and a white solid gradually
precipitated. After cooling to room temperature the mixture was
filtered, and the white solid was washed with cold methanol and
dried in Vacuo to give a white powder. Yield: 2.31 g (4.9 mmol,
83%). Anal. Calcd for C24H22Cl2N2O2S: C, 60.89; H, 4.70; N, 5.92;
S, 6.77; Cl, 14.81. Found: C, 60.79; H, 4.79; N, 5.93; S, 6.63; Cl,
15.06.
cis-1,2-Bis(o-chlorophenyl)cyclopentane (cis-10). Tosylhydra-
zone (9) (1.51 g, 3.2 mmol) was dissolved in 90 mL of dry
chloroform. Under vigorous stirring catecholborane (0.57 g, 4.8
mmol) was added dropwise via a syringe. After 3 h stirring at room
temperature solid sodium acetate trishydrate (1.57 g, 10.3 mmol)
was added and the mixture was heated to reflux for 4 h. The white
suspension was washed with water and brine and dried over
anhydrous MgSO4. The solvent was evaporated and a yellow oil
was obtained, which was purified by column chromatography
(petroleum ether/ethyl acetate, 95/5). Yield: 0.61 g of a white solid
(2.1 mmol, 65%). Anal. Calcd for C17H16Cl2: C, 70.11; H, 5.54;
Cl, 24.35. Found: C, 70.40; H, 5.71; Cl, 24.11.
Conclusion
A series of bisphosphonite ligands with (bi)cycloalkyl spacers
was synthesized covering a range of different steric properties
at the spacer and at the phosphacycle. Their complexation
behavior with Ni(COD)2 was investigated by NMR studies and
yielded (monochelate)Ni(COD) complexes in all cases. Forma-
tion of bis(diphosphonite) complexes assumed to be catalytically
inactive was not observed. The ligands were successfully applied
in the hydrocyanation of styrene and 1,3-butadiene as well as
in the isomerization of 2M3BN. They represent a new class of
highly active and selective catalysts for these reactions. Turnover
numbers of up to 935 for the isomerization of 2M3BN and up
to 644 for the hydrocyanation of 1,3-butadiene open a potential
for further tailoring new ligands by electronic and steric tuning.
cis-1,2-Bis[o-{bis(diethylamino)phosphanyl}phenyl]cyclopen-
tane (11). At -78 °C a solution of cis-1,2-bis(o-chlorophenyl)cy-
clopentane (10) (0.78 g, 2.7 mmol) in 10 mL of dry THF was added
to a suspension of lithium powder (0.19 g, 26.0 mol, 10 equiv) in
10 mL of dry THF. After 20 min the suspension turned dark purple.
The mixture was stirred for an additional 1.5 h and filtered over
Celite in a cooled frit. The solid was washed twice with 5 mL of
THF, and the purple solution was collected in a precooled Schlenk
tube. Via a syringe bis(diethylamino)chlorophosphane (1.14 g, 5.4
mmol, 2.1 equiv) was added at once (color turned from purple to
light yellow), and the mixture was allowed to warm to room
temperature. The solvent was evaporated in Vacuo, and the yellow
oil was extracted three times with 10 mL of dry pentane. While
LiCl remained as a white powder, the extracts were concentrated
in Vacuo. At -80 °C a white solid precipitated. Yield: 1.08 g of
colorless crystals (1.9 mmol, 71%). 31P{1H} NMR (C6D6, 121.5
MHz): δ 95.9. Anal. Calcd for C32H56N4P2: C, 69.44; H, 9.89; N,
9.82; P, 10.86. Found: C, 69.23; H, 10.05; N, 9.66; P, 10.82.
Experimental Section
General Procedures. All reactions were carried out under an
atmosphere of dry argon with standard Schlenk-tube and syringe-
cannula techniques. Solvents were dried according to standard
procedures and saturated with argon prior to use. Chemicals were
purchased or prepared according to published procedures:
Ni(COD)2,31 ClP(NEt2)2,39 6,19 7,18,20 8,21 P(O-p-tolyl)3.40 2M3BN
and authentic samples of the other nitriles were donations of BASF
AG. Flash chromatography was performed with silica gel 60 from
Machery and Nagel (0.040-0.063 mm). NMR spectra were
recorded using a Bruker DRX 250, DRX 300, or DRX 500
spectrometer. 31P{1H} NMR spectra (101.3, 121.5, 202.5 MHz)
were calibrated to an external standard (85% H3PO4). Abbreviations
used are s ) singlet, d ) doublet, t ) triplet, dt ) doublet of triplet,
m ) multiplet. Gas chromatography was performed on a Chrompak
CP-9002 using a Chrompak CP-Wax 52 CB (30 m, carrier gas 50
kPa of N2, FID detector). FT-IR spectra were recorded on a Bruker
Equinox 55. Mass spectroscopy was performed on a Jeol JMS-
700. Melting points were measured using a melting point apparatus
cis-1,2-Bis[o-(2-dibenzo[d,f]-1,3,2-dioxaphosphepinyl)phenyl]-
cyclopentane (1). Compound 11 (1.45 g, 2.5 mmol) and 2,2′-
dihydroxybiphenyl (0.95 g, 5.0 mmol, 2 equiv) were dissolved in
10 mL of dry toluene and heated to 110 °C for 16 h. The solvent
was removed in Vacuo and the yellow solid recrystallized from
acetone to give colorless crystals. Yield: 0.67 g (1.0 mmol, 40%).
31P{1H} NMR (CDCl3, 121.5 MHz): δ 179.4. Anal. Calcd for
C41H32O4P2 · 0.5C3H6O: C, 75.10; H, 5.19; P, 9.11. Found: C, 75.05;
H, 5.35; P, 9.36.
(1-K2P)Ni(COD). To a solution of 1 (100 mg, 0.16 mmol) in 5
mL of dry toluene was added Ni(COD)2 (42 mg, 0.15 mmol), and
the mixture was stirred for 1 day. After filtration over Celite, the
filtrate was concentrated to 0.5 mL. At -20 °C a bright yellow
solid precipitated. Yield: 61 mg (0.08 mmol, 49%). 1H NMR (C6D6,
(39) Sakai, J.; Schweizer, W. B.; Seebach, D. HelV. Chim. Acta 1993,
76, 2654.
(40) General method given by: Kosolapoff, G. M. Organophosphorous
Compounds; John Wiley and Sons, Inc.: New York, 1950; p 184.
3
300 MHz): δ 2.09 – 2.33 (m, 8H, CH2-CHdCH), 4.91 (d, JH,H
) 5.7 Hz, 2H, CHdCH), 5.17 (d,3JH,H ) 5.7 Hz, 2H, CHdCH),
13C{1H} NMR (C6D6, 75.5 MHz): δ 30.6 (CH2-CHdCH), 31.0

2198 Organometallics, Vol. 27, No. 10, 2008
Göthlich et al.
Table 4. Crystal Data and Structure Refinement Details for 1, 3, 4, 5, and (2-K2P)Ni(COD)
1
3
4
5 · 0.5(C3H6O)
(2-κ2P)Ni(COD) · 3(C4H8O)
empirical formula
fw
temp (K)
cryst syst
space group
Z
C41H32O4P2
650.61
200(2)
monoclinic
P21/c
C43H36O4P2
678.66
200(2)
C42H34O4P2
664.63
200(2)
monoclinic
P21/c
C
44.50H41O4.50P2
C77H76NiO7P2
1234.03
200(2)
709.71
200(2)
triclinic
triclinic
triclinic
j
j
j
P1
P1
P1
4
4
4
2
2
unit cell dimens
a (Å)
b (Å)
16.6462(4)
12.4328(1)
15.9533(3)
90
98.7460(10)
90
3263.3(1)
1.32
0.18
9.0996(2)
12.0836(2)
34.1996(5)
90.634(1)
93.272(1)
110.559(1)
3513.3(1)
1.28
17.4188(6)
12.4336(4)
15.9652(5)
90
101.497(1)
90
3388.3(2)
1.30
0.17
10.8707(6)
13.7375(7)
14.6381(8)
69.452(2)
69.297(1)
68.116(1)
1836.0(2)
1.28
11.6124(2)
13.3244(2)
21.0298(1)
83.656(1)
82.280(1)
80.112(1)
3163.75(7)
1.29
c (Å)
R (deg)
ꢀ (deg)
γ (deg)
V (Å3)
calcd density (g/cm3)
abs coeff (mm-1
)
0.17
0.16
0.41
θ range for data collectn (deg)
2.0 to 25.7
-19 e h e 20
14e k e 14
-18 e l e 19
23 893
5687 (0.075)
3139
0.98 and 0.94
5687/0/432
0.97
2.1 to 27.6
-11 e h e 11
-15 e k e 15
-44 e l e 44
36 337
1.2 to 24.1
-20 e h e 20
14 e k e 14
-18 e l e 18
26 354
5394 (0.133)
3117
0.98 and 0.78
5394/0/441
1.13
1.6 to 20.8
-10 e h e 10
-13 e k e 13
-14 e l e 14
10 569
3849 (0.058)
2545
0.81 and 0.61
3849/8/479
1.06
1.8 to 27.5
-15 e h e 15
-17 e k e 17
-27 e l e 27
32 713
14 452 (0.082)
7744
0.95 and 0.81
14 452/70/846
1.01
index ranges
no. of reflns collected
no. of indep rflns (R(int))
no. of obsd rflns (I > 2σ(I))
max., min. transmns
no. of data/restraints/params
goodness of fit on F2
final R indices (I > 2σ(I))
R1
16 129 (0.117)
11 129
16 129/0/883
2.53
0.045
0.193
0.058
0.050
0.063
wR2
0.079
0.21 and -0.31
0.442
1.59 and -0.83
0.117
0.29 and -0.30
0.111
0.28 and -0.33
0.120
0.46 and -0.39
largest diff peak, hole (e Å-3
)
(CH2-CHdCH), 88.5 (CH2-CHdCH), 89.4 (CH2-CHdCH).
31P{1H} NMR, (C6D6, 121.5 MHz): δ 196.1. Anal. Calcd for
C49H44O4P2Ni: C, 71.99; H, 5.42; P, 7.58. Found: C, 71.79; H, 5.57;
P, 7.30.
of pyridinium chlorochromate (PCC) and 2.50 g of ground
molecular sieves (4 Å) were added, and the mixture was stirred at
room temperature. After 30 min the red suspension turned brownish.
Stirring was continued for 4 h. The mixture was filtered over silica,
and the solvent was removed in Vacuo. The light brown oil was
purified by flash chromatography (petroleum ether/ethylacetate, 80/
20). Yield: 1.76 g (8.4 mmol, 89%) of a colorless solid. Anal. Calcd
for C12H13OCl: C, 69.07; H, 6.28; Cl, 16.99. Found: C; 68.84; H,
6.28; Cl, 16.94.
rac-cis-1,2-Bis[o-(2-dinaphtho[d,f]-1,3,2-dioxaphosphepinyl)phe-
nyl]cyclopentane (2). The compound was prepared similarly to 1
from 11 (1789 mg, 3.13 mmol) and rac-2,2′-dihydroxybinaphthyl
(1.78 g, 6.3 mmol, 2 equiv). Yield: 1.03 g, (1.2 mmol, 38%).
31P{1H} NMR (CD2Cl2, 121.5 MHz): δ 177.4 (d, 3JPP ) 41.8 Hz),
3
178.7 (d, JPP ) 41.8 Hz). HR-MS (FAB+): 851.2498 (calcd for
2,3-Bis(o-chlorophenyl)cyclohex-1-ene (14). 1,2-Bromochlo-
robenzene (9.11 g, 47.45 mmol, 1.2 equiv) was dissolved in 40
mL of a 1:1 mixture of dry THF/diethyl ether and cooled in a liquid
nitrogen/pentane cooling bath to -110 °C. Via dropping funnel
n-BuLi (29.7 mL, 47.45 mmol, 1.6 M, 1.2 equiv) was added within
30 min, and the mixture was stirred for 45 min. A white solid
gradually precipitated. Via a funnel a solution of 13 (8.252 g, 39.54
mmol, 1.0 equiv) in 40 mL of a 1/1 mixture of THF/diethyl ether
was added, stirred at -110 °C, and warmed to room temperature
overnight. The mixture was hydrolyzed at 0 °C by addition of
saturated NH4Cl solution and the aqueous layer extracted three times
with ether, washed with water and brine, and dried over Na2SO4.
After removal of the solvent the yellow oil was dissolved in 150
mL of dry toluene and heated to reflux with catalytic amounts of
p-toluenesulfonic acid in a water separator apparatus for 20 h. The
solution was washed twice with saturated soda solution and water
and dried over MgSO4. Purification by flash chromatography
(petroleum ether/ethyl acetate, 99/1) provided a colorless solid.
Yield: 10.21 g (33.69 mmol, 85%). Anal. Calcd for C18H16Cl2: C,
71.30; H, 5.32; Cl, 23.38. Found: C, 71.01; H, 5.24; Cl, 23.09.
cis-1,2-Bis(o-chlorophenyl)cyclohexane (15). A 100 mL steel
autoclave (Berghoff) was charged with a solution of 2,3-bis(o-
chlorophenyl)cyclohex-1-ene (14) (2.00 g, 6.6 mmol) in 50 mL of
petroleum ether (30-75 °C), and 0.20 g (10%) of palladium/
charcoal was added. It was pressurized with 15 bar of hydrogen
and heated to 60 °C for 16 h under vigorous stirring. The suspension
was filtered and concentrated in Vacuo. The colorless solid
crystallizing from the mixture was identified as pure cis-isomer.
Yield: 0.67 g cis-isomer of altogether 1.89 g (6.2 mmol, 94%) of
C57H40O4P2: 851.2480, err. ) 1.8 ppm). Anal. Calcd for
C57H40O4P2 · 0.5C3H6O: C, 79.85; H, 4.93; P, 7.01. Found: C, 79.87;
H, 4.86; P, 7.17.
cis-1,2-Bis[o-(2-dibenzo[d,g]-1,3,2-dioxaphosphocinyl)phenyl]-
cyclopentane (3). The compound was prepared analogously to 1
from 11 (1.43 g, 2.5 mmol) and bis(2-hydroxyphenyl)methane (1.00
g, 5.0 mmol, 2 equiv). Yield: 0.55 g (0.8 mmol, 32%). 31P{1H}
NMR (C6D6, 202.5 MHz): δ 161.5. Anal. Calcd for C43H36O4P2:
C, 76.10; H, 5.34; P, 9.13. Found: C, 76.11; H, 5.43; P, 8.98.
trans-2-Bis(o-chlorophenyl)cyclohexan-1-ol (12). 1,2-Bromo-
chlorobenzene (407 mg, 2.12 mmol, 2.0 equiv) was dissolved in a
1:1 mixture of dry THF and diethyl ether and cooled in a liquid
nitrogen/pentane cooling bath to -110 °C. Via a syringe n-BuLi
(1.3 mL, 2.12 mmol, 1.6 M, 2.0 equiv) was added slowly, and the
mixture stirred for 45 min. A white solid gradually precipitated.
Cyclohexene oxide (104 mg, 1.06 mmol, 1.0 equiv) was added
followed by dropwise addition of (226 mg, 1.59 mmol, 1.5 equiv)
of BF3-etherate. After 1 h the mixture was allowed to warm to 0
°C and hydrolyzed by addition of 5 mL of saturated NH4Cl solution.
The aqueous layer was extracted three times with 20 mL of ether,
washed with water and brine, and dried over Na2SO4. After removal
of the solvent the remaining yellow oil was purified by flash
chromatography (petroleum ether/ethylacetate, 80/20). Yield: 200
mg (0.95 mmol, 90%) of a colorless solid. Anal. Calcd for
C12H15OCl: C, 68.41; H, 7.18; Cl, 16.83. Found: C, 68.28; H, 7.12;
Cl, 16.61.
2-(o-Chlorophenyl)cyclohexan-1-one (13). Compound 12 (1.99
g, 9.4 mmol) was dissolved in 20 mL of dry CH2Cl2. Then 3.99 g

Nickel-Catalyzed Hydrocyanation of Olefins
Organometallics, Vol. 27, No. 10, 2008 2199
isomer mixture. Anal. Calcd for C18H18Cl2: C, 70.85; H, 5.94; Cl,
23.23. Found: C, 70.85; H, 5.90; Cl, 23.35.
endo-cis-2,3-Bis[o-{bis(diethylamino)phosphanyl}phenyl]nor-
bornane (22). This compound was prepared analogously to 11 from
21 (0.942 g, 3.09 mmol), lithium powder (0.214 g, 30.86 mmol,
10 equiv), and bis(diethylamino)chlorophosphane (1.365 g, 6.48
mmol, 2.1 equiv) Yield: yellow oil (1.212 g, 2.07 mmol, 67%),
used without further purification. 31P NMR (C6D6, 101.3 MHz): δ
95.6. MS (FD+): m/z (%) 596.6 (100), 422.4 (15).
cis-1,2-Bis[o-(2-dibenzo[d,f]-1,3,2-dioxaphosphepinyl)phenyl]-
cyclohexane (5). This compound was prepared analogously to 1
from 22 (625 mg, 1.04 mmol) and 2,2′-dihydroxybiphenyl (386
mg, 2.09 mmol). After recrystallization from acetone a colorless
powder was obtained. Yield: 145 mg (0.21 mmol, 21%). 31P NMR
(C6D6, 121.5 MHz): δ 179.5. HR-MS (FAB+): m/z ) 677.2002
(calcd for C43H35O4P2: m/z ) 677.2010, err. ) -0.8 ppm). Anal.
Calcd for C43H34O4P2 · 0.5C3H6O: C, 75.74; H, 5.28; P, 8.78. Found:
C, 75.49; H, 5.39; P, 8.69.
cis-1,2-Bis[o-{bis(diethylamino)phosphanyl}phenyl]cyclohex-
ane (16). The compound was prepared analogously to 11 from 15
(0.942 g, 3.09 mmol), lithium powder (0.214 g, 30.86 mmol, 10
equiv), and bis(diethylamino)chlorophosphane (1.365 g, 6.48 mmol,
2.1 equiv). Yield: white solid, 1.212 g (2.07 mmol 67%). 31P NMR
(C6D6, 121.5 MHz): δ 95.6. HR-MS (FAB+): 585.4178 (calcd for
C34H59N4P2: 585.4215, err. ) -6.2 ppm). Anal. Calcd for
C34H58N4P2: C, 69.83; H, 9.99; N, 9.58; P, 10.59. Found: C, 69.38;
H, 9.82, N, 9.58; P, 10.50.
cis-1,2-Bis[o-(2-dibenzo[d,f]-1,3,2-dioxaphosphepinyl)phenyl]-
cyclohexane (4). The compound was prepared analogously to 1
from 16 (606 mg, 1.04 mmol) and 2,2′-dihydroxybiphenyl (388
mg, 2.08 mmol, 2 equiv). After recrystallization from acetone, cubic,
colorless crystals were obtained. Yield: 255 mg (0.38 mmol, 35%).
31P NMR (C6D6, 202.5 MHz): δ 179.8. HR-MS (FAB+): 665.1998
(calcd for C42H35O4P2: 665.2010, err. ) -1.2 ppm). Anal. Calcd
for C42H34O2P2 · C3H6O: C, 74.78; H, 5.58; P, 8.57. Found: C, 74.78;
H, 5.45; P, 8.61.
Hydrogen cyanide was generated by addition of sulfuric acid to
a solution of potassium cyanide in water.
CAUTION! HCN is a highly toxic, volatile liquid (mp -13 °C,
bp 27 °C). To prevent polymerization (highly exothermic), non-
stabilized HCN should be stored at temperatures below its melting
point. It should be handled only in a well-ventilated fume hood
and by a team of at least two technically qualified persons who
have received appropriate medical training for treating HCN
poisoning. Mandatory precautions also include the use of HCN
monitoring equipment.41
2-(o-Chlorophenyl)norbornene (17). In a 500 mL three-necked
flask with reflux condenser and dropping funnel 0.73 g (30.1 mmol,
1.1 equiv) of mechanically activated magnesium turnings was
covered with 5 mL of a solution of bromochlorobenzene (5.23 g,
27.3 mmol) in 90 mL of dry ether. The reaction was started by
short heating, and the main portion of the solution was added
dropwise to keep the mixture boiling slightly. After heating for
4 h under reflux conditions a solution of norcamphor (2.11 g, 19.1
mmol, 1 equiv) in 80 mL of dry ether was added dropwise, and
the mixture was refluxed for an additional 5 h. It was then
hydrolyzed at 0 °C by addition of a saturated NH4Cl solution, and
the aqueous layer was extracted three times with ether, washed with
water and brine, and dried over Na2SO4. After removal of the
solvent the yellow oil was dissolved in 100 mL of dry benzene
and heated to reflux with catalytic amounts of p-toluenesulfonic
acid in a water separator apparatus for 16 h. The solution was
washed twice with saturated soda solution and water and dried over
MgSO4. Purification by flash chromatography (petroleum ether)
provided a colorless oil. Yield: 2.64 g (12.9 mmol, 68%).
trans-3-exo-(o-Chlorophenyl)norbornan-2-ol (18). A Schlenk
tube was charged with a solution of 17 (3.24 g 15.9 mmol) in 5
mL of dry pentane. Via a syringe a solution of 0.82 g of BH3-1,4-
oxathiane in 10 mL of dry pentane was added, and the mixture
was refluxed for 5.5 h. At room temperature 7.5 mL of ethanol, 5
mL of NaOH solution (3 M), and, dropwise over a period of 15
min, 2 mL of H2O2 (30%) were added. The slurry was refluxed
again for 1 h and subsequently poured on ice. The organic layer
was separated and the aqueous layer extracted three times with ether.
The combined organic layers were dried over Na2SO4 and
evaporated in Vacuo. Purification by flash chromatography (petro-
leum ether/ethyl acetate, 99/1) yielded a colorless solid. Yield:
1.44 g (6.5 mmol, 41%). Anal. Calcd for C13H15ClO: C, 70.11; H,
6.79; Cl, 15.92. Found: C, 69.97; H, 6.75; Cl, 15.77.
trans-3-exo-(o-Chlorophenyl)norbornan-2-one (19). This com-
pound was prepared analogously to 13 from 18 (2.17 g, 9.4 mmol).
Yield: white solid, 1.84 g (8.4 mmol, 86%). Anal. Calcd for
C13H13ClO: C, 70.75; H, 5.94; Cl, 16.06. Found: C, 70.65; H, 5.81;
Cl, 16.04.
2,3-Bis(o-chlorophenyl)norborn-2-ene (20). The compound was
prepared analogously to 14 from 19 (7.50 g, 34.0 mmol). Yield:
white solid, 8.93 g (28.4 mmol, 84%). Anal. Calcd for C19H16Cl2:
C, 72.39; H, 5.12; Cl, 22.49. Found: C, 72.34; H, 5.20; Cl, 22.28.
endo-cis-1,2-Bis(o-chlorophenyl)norbornane (21). This com-
pound was prepared analogously to 15 from 20 (0.738 g, 2.34
mmol). Conditions: 20 bar, 90 h, 35 °C. Yield: white solid, 0.438
g (1.38 mmol, 59%). Anal. Calcd for C19H18Cl2: C, 71.93; H, 5.72;
Cl, 22.35. Found: C, 71.95; H, 5.72; Cl, 22.29.
Hydrocyanation of Styrene. In a typical experiment, a Schlenk
tube containing a magnetic stirring bar was charged with 6.1 mg
(22.0 µmol) of Ni(COD)2 in 0.5 mL of dry toluene, 1.05 equiv of
ligand and 0.5 mL of toluene were added, and 20 min of
preformation time was allowed. Then 100 µL of diethylene diglycol
ether (internal standard) and the appropriate amount of styrene were
added, and the mixture was cooled to -78 °C. In another Schlenk
tube HCN was weighed, also cooled to -78 °C, dissolved in 1 mL
of dry toluene, and canulated into the catalyst/styrene mixture. After
purging twice with 1 mL of toluene the Schlenk tube was placed
in a heating bath at 60 °C. Samples were taken after 1.5, 3, and
16 h by cooling the Schlenk tube to -30 °C, diluted in diethyl
ether, and analyzed by temperature-controlled gas chromatography.
Hydrocyanation of Butadiene. This reaction was performed in
a glass autoclave equipped with a valve and magnetic stirring bar.
In a typical experiment the autoclave was charged with 3.0 mg
(10.9 µmol) of Ni(COD)2 in 0.5 mL of dry toluene; then 1.05 equiv
of ligand and 0.5 mL of toluene were added. After 20 min
preformation time 100 µL of diethylene diglycol ether (internal
standard) was added and the mixture was cooled to -78 °C. In a
Schlenk tube 1,3-butadiene was condensed (after drying by passing
a column containing 4 Å molecular sieves) and weighed. The
appropriate amount of HCN was added using a microliter syringe
and the Schlenk tube weighed again. After cooling to -78 °C, the
mixture was dissolved in 1 mL of dry toluene and canulated into
the cooled autoclave through the valve, and the canula was purged
twice with 1 mL of toluene. The autoclave was placed in a heating
bath at 120 °C. Samples were taken after 1.5, 3, and 16 h by cooling
to -30 °C, diluted in diethyl ether, and analyzed by temperature-
controlled gas chromatography.
Isomerization of 2M3BN. A Schlenk tube containing a magnetic
stirring bar was charged with 2.8 mg (10.2 µmol) of Ni(COD)2 in
0.5 mL of dry toluene. Then 10.7 µmol (1.05 equiv) of ligand and
0.5 mL of toluene were added, 20 min of preformation time was
allowed, and 100 µL of diethylene diglycol ether (internal standard)
and 412.9 mg (5.090 mmol) 2M3BN were added. The syringe was
purged three times with 1 mL of toluene, and the autoclave was
placed in a heating bath at 120 °C. Samples were taken after 1.5,
(41) For additional details on using HCN safely, see: Prudent Practices
for Handling Hazardous Chemicals in Laboratories; National Academy
Press: Washington, DC, 1981; p 45.

2200 Organometallics, Vol. 27, No. 10, 2008
Göthlich et al.
3, and 16 h by cooling to -30 °C, diluted in diethyl ether, and
analyzed by temperature-controlled gas chromatography.
X-ray Diffraction Studies of 1, 3, 4, 5, and (2-K2P)Ni(COD).
Crystals suitable for X-ray diffraction analyses were obtained by
isothermic distillation of the solvent from a saturated solution of
the substances (1, 3, 4, 5: acetone, (2-κ2P)Ni(COD): THF) in an
apparatus consisting of two Schlenk tubes connected by a frit.
An empirical absorption correction was applied using SADABS
based on the Laue symmetry of the reciprocal space, except for 3,
which has a low-quality data set. The structures were solved by
direct methods and refined against F2 with a full-matrix least-
squares algorithm using the SHELXTL-PLUS (5.03) software
package.42 Crystal data and structure refinement details are given
in Table 4.
Acknowledgment. We thank BASF AG for financial
support of this work and for generous donation of chemicals.
Authentic samples of the nitriles were kindly provided by
Dr. Kunsmann-Keitel and Dr. Fischer of BASF. We are
grateful to Dr. C. Jokisch for editing an early version of the
manuscript and to Jochen Kurz for contributions to experi-
mental work during his internship in our group.
Supporting Information Available: CIF files giving X-ray
crystallographic data from 1, 3, 4, 5, and (2-κ2P)Ni(COD). Pdf file
giving further details of catalytic experiments performed. This
material is available free of charge via the Internet at http://pubs.acs.
org.
(42) Sheldrik, G. M. Bruker Analytical X-ray-DiVision; Madison, WI,
1997.
OM701140C