First optically active phosphapalladacycle bearing a phosphorus atom in an axially chiral environment

Article abstract of DOI:10.1021/om800654r

Direct C-H bond activation in the (S_a)-BINOL-derived phosphite (HL) afforded the dimeric cyclopalladated complex (S_a,5 _a)-{Pd(n²-L)(μ-C1)}₂ (1), which is the first optically active phosphapalladacycle

Full text of DOI:10.1021/om800654r

Organometallics 2009, 28, 425–432
425
First Optically Active Phosphapalladacycle Bearing a Phosphorus
Atom in an Axially Chiral Environment
Valery V. Dunina,*,† Pavel A. Zykov,†,‡ Michail V. Livantsov,† Ivan V. Glukhov,‡
Konstantin A. Kochetkov,‡ Igor P. Gloriozov,† and Yuri K. Grishin*,†
Department of Chemistry, M.V. LomonosoV Moscow State UniVersity, 1 Leninskie Gory, 119991 Moscow,
Russian Federation, and A.N. NesmeyanoV Institute of Organoelement Compounds, Russian Academy of
Sciencies, VaViloVa Street 28, 119991 Moscow, Russian Federation
ReceiVed July 10, 2008
Direct C-H bond activation in the (Sa)-BINOL-derived phosphite (HL) afforded the dimeric
cyclopalladated complex (Sa,Sa)-{Pd(η2-L)(µ-Cl)}2 (1), which is the first optically active phosphapal-
ladacycle bearing a phosphorus atom in an axially chiral environment. The ortho-palladated structure
of complex 1 was confirmed by spectral (1H and 31P) investigations of mononuclear derivatives and
the X-ray diffraction study of the phosphane adduct (η2-L)PdCl(PPh3) (3). The enantiomeric purity
of the starting ligand remained unchanged in the PC-palladacycle under the thermal conditions used
for the cyclopalladation (∼110 °C); this fact was confirmed by the 31P NMR spectroscopy after
chiral derivatization of dimer (Sa,Sa)-1 with the (RC)-valinate auxiliary ligand. The trans(N,C)-
configuration of the valinate complex (4) was supported by DFT calculations. The chirality transfer
in the new system was discussed on the basis of X-ray diffraction data for the phosphane adduct
rac-3 and DFT calculations performed for both mononuclear derivatives.
iridium- and palladium-catalyzed processes was established6a,b
or proposed.6c Surprisingly, despite a high catalytic activity of
achiral phosphite PC-palladacycles7 and excellent results achieved
in asymmetric catalysis with BINOL-derived phosphite ligands,
cyclopalladated compounds (CPCs) obtained from the same type
of ligands have remained unknown until now. Recently8 several
pincer PCP-complexes based on bis(phosphites) derived from
binaphthol (Ia) or biphenanthrol (Ib) were reported. In addition,
only two examples of optically active phosphite PC-pallada-
cycles (IIa,b) with rather distant carbon stereocenters9 have also
been described (Chart 1).
Introduction
Coordination complexes of transition metals with mono-1 or
bidentate2 P-donor ligands bearing elements of axial chirality,
including BINOL-derived phosphites3 and phosphoramidites,4,5
are well known as very efficient asymmetric catalysts. Participa-
tion of the corresponding PC-metallacycles in some of the
* Corresponding author. Fax: (495) 932 8846. E-mail: dunina@
org.chem.msu.ru.
† M.V. Lomonosov Moscow State University.
‡ A.N. Nesmeyanov Institute of Organoelement Compounds.
(1) (a) Ansell, J.; Wills, M. Chem. Soc. ReV. 2002, 31, 259. (b) Hayashi,
T. Acc. Chem. Res. 2000, 33, 354. (c) Hayashi, T. J. Organomet. Chem.
1999, 576, 195.
Chart 1
(2) (a) McCarthy, M.; Guiry, P. J. Tetrahedron 2001, 57, 3809. (b) Guiry,
P. J.; McCarthy, M.; Lacey, P. M.; Saunders, C. P.; Kelly, S.; Connolly,
D. J. Curr. Org. Chem. 2000, 4, 821.
(3) (a) Reetz, M. T.; Mehler, G.; Bondarev, O. Chem. Commun. 2006,
2292. (b) Reetz, M. T.; Meiswinkel, A.; Mehler, G.; Angermund, K.; Graf,
M.; Thiel, W.; Mynott, R.; Blackmond, D. G. J. Am. Chem. Soc. 2005,
127, 10305. (c) Gergely, I. G.; Hegedu¨s, C.; Gulya´s, H.; Sco¨llo¨sy, A.;
Monsees, A.; Riermeier, Th.; Bakos, J. Tetrahedron: Asymmetry 2003, 14,
1087. (d) Sturla, Sh. J.; Buchwald, St. L. J. Org. Chem. 2002, 67, 3398.
(e) Reetz, M. T.; Mehler, G.; Meiswinkel, A.; Sell, Th. Tetrahedron Lett.
2002, 43, 7941. (f) Chen, W.; Xiao, J. Tetrahedron Lett. 2001, 42, 2897.
(g) Reetz, M. T.; Mehler, G. Angew. Chem., Int. Ed. 2000, 39, 3889. (h)
Yan, M.; Yang, K.-Y; Chan, A. S. C. Chem. Commun. 1999, 11. (i) Yan,
M.; Chan, A. S. C. Tetrahedron Lett. 1999, 40, 6645.
(4) (a) Kurihara, K.; Sugishita, N.; Oshita, K.; Piao, D.; Yamamoto,
Ya.; Miyaura, N. J. Organomet. Chem. 2007, 692, 428. (b) Zhang, A.;
RajanBabu, T. V. J. Am. Chem. Soc. 2006, 128, 54. (c) Zeng, Q.-H.; Hu,
X.-P.; Duan, Zh.-Ch.; Liang, X.-M.; Zheng, Zh. J. Org. Chem. 2006, 71,
393. (d) Vallianatou, K. A.; Kostas, I. D.; Holz, J.; Bo¨rner, A. Tetrahedron
Lett. 2006, 47, 7947. (e) Welter, C.; Moreno, R. M.; Streiff, St.; Helmchen,
G. Org. Biomol. Chem. 2005, 3, 3266. (f) de Vries, A. H. M.; Boogers,
J. A. F.; van den Berg, M.; Pen˜a, D.; Minnaard, A. J.; Feringa, B. L.; de
Vries, J. G. Pharma Chem. 2003, 33. (g) Zeng, Q.; Liu, H.; Cui, X.; Mi,
A.; Jiang, Ya.; Li, X.; Choi, M. C. K.; Chan, A. S. C. Tetrahedron:
Asymmetry 2002, 13, 115. (h) van den Berg, M.; Minnaard, A. J.; Schudde,
E. P.; van Esch, J.; de Vries, A. H. M.; de Vries, J. G.; Feringa, B. L.
J. Am. Chem. Soc. 2000, 122, 11539. (i) Feringa, B. L. Acc. Chem. Res.
2000, 33, 346. (j) Arnold, L. A.; Imbos, R.; Mandoli, A.; de Vries, A. H. M.;
Naasz, R.; Feringa, B. L. Tetrahedron 2000, 56, 2865.
The aim of this work was to study the possibility of direct
cyclopalladation of BINOL-derived phosphites as a route to
(5) (a) Trost, B. M.; Silverman, St. M.; Stambuli, J. P. J. Am. Chem.
Soc. 2007, 129, 12398. (b) Ohmura, T.; Taniguchi, H.; Suginome, M. J. Am.
Chem. Soc. 2006, 128, 13682. (c) Trost, B. M.; Stambuli, J. P.; Silverman,
St.M.; Schwo¨rer, U. J. Am. Chem. Soc. 2006, 128, 13328. (d) Zhang, A.;
RajanBabu, T. V. J. Am. Chem. Soc. 2006, 128, 5620. (e) Boele, M. D. K.;
Kamer, P. C. J.; Lutz, M.; Spek, A. L.; de Vries, J. G.; van Leeuwen,
P. W. N. M.; van Strijdonck, G. P. F. Chem.-Eur. J. 2004, 10, 6232.
10.1021/om800654r CCC: $40.75
2009 American Chemical Society
Publication on Web 01/05/2009

426 Organometallics, Vol. 28, No. 2, 2009
Dunina et al.
Scheme 1
enantiopure PC-palladacycles and to estimate efficiency of
chirality transfer from an axial chiral environment of the
phosphorus atom.
Results and Discussion
Phosphite Cyclopalladation. For steric promotion of an
intramolecular C-H bond activation10 a rather bulky phosphite
ligand (Sa)-HL was chosen for cyclopalladation. Both racemic
and enantiopure phosphites HL were prepared by a known
route8d,10c,11 that includes a reaction of the in situ obtained
BINOL-derived phosphorochloridite4j with 2,4-di-tert-butylphe-
nol in the presence of a base. Phosphite HL possesses moderate
oxidative and hydrolytic stability: keeping a pure sample in a
chloroform solution in air for a week resulted in 10% decom-
position (31P data). To our knowledge, this ligand is a new
member12 of a large group of the BINOL-derived ArO-
substituted phosphites.3g,i,13-15
Scheme 2
Scheme 3
Two protocols were reported for cyclopalladation of achiral
phosphite ligands (HL′): (i) a two-step procedure through
9a,10b,16,17
intermediate coordination complex Pd(HL′)2Cl2
and
(ii) a one-step synthesis by reaction of PdCl2 with phosphite
HL′ in a 1:1 ratio at heating.10c,11 Typically, the latter method
provides a high yield of CPCs from simple triarylphosphites
(up to 98%10c,18), which may be decreased to 43-53% in the
case of encumbered ligands.8d,11
protocols to our system and to use the more electrophilic reagent
Pd(OAc)2 resulted in palladium black precipitation and forma-
tion of complex mixtures of coordination complexes. However,
the reaction of phosphite HL with PdCl2(NCPh)2 in refluxing
toluene provided racemic and optically active cyclopalladated
dimers, rac-1 and (Sa,Sa)-1a, in 40-43% yield after column
chromatography (Scheme 1). In a similar reaction carried out
in 1,2-dichloroethane (DCE), the yield of rac-1 was slightly
lower, 37%. Attempts to promote C-H bond activation with
Et3N as a base in DCE (cf. ref 8d) resulted in palladium(II)
reduction.
A very low solubility of the racemic dimer 1 complicated its
purification. To overcome this obstacle, dimer rac-1 was
converted into its more soluble mononuclear pyridine derivative
(2) followed by its chromatographic purification (cf. ref 19).
Strong trans-influence of both carbanionic and phosphorus donor
atoms of the PC-palladacycle facilitated elimination of the
auxiliary pyridine ligand from adduct rac-2 with formation of
the pure dimer rac-1 (TLC and NMR data; Scheme 2).
Dynamic mobility of dimeric CPCs20 and their existence as
mixtures of syn/anti and meso/dl isomers prevent their use for
spectral studies; so we converted the dimer rac-1 into its
mononuclear phosphane derivative rac-3 by the reaction of
chloride bridge cleavage (Scheme 3).
Cyclopalladation of phosphite HL appeared to be a rather
difficult task. Thus, our attempts to adopt the aforementioned
(6) (a) Markovic´, D.; Hartwig, J. F. J. Am. Chem. Soc. 2007, 129, 11680.
(b) Kiener, Ch. A.; Shu, Ch.; Incarvito, Ch.; Hartwig, J. F. J. Am. Chem.
Soc. 2003, 125, 14272. (c) Lo´pez, F.; Ohmura, T.; Hartwig, J. F. J. Am.
Chem. Soc. 2003, 125, 3426.
(7) (a) Bedford, R. B.; Betham, M.; Blake, M. E.; Frost, R. M.; Norton,
P. N.; Hursthouse, M. B.; Lo´pez-Nicola´s, R.-M. Dalton Trans. 2005, 2774.
(b) Bedford, R. B.; Coles, S. J.; Hursthouse, M. B.; Scordia, V. J. M. Dalton
Trans. 2005, 991. (c) Bedford, R. B. Chem. Commun. 2003, 1787 (review).
(d) Bedford, R. B.; Cazin, C. S. J.; Hazelwood (ne´e Welch), S. M. Angew.
Chem. Int. Ed. 2002, 41, 4120. (e) Bedford, R. B.; Hazelwood (ne´e Welch),
S. M.; Limmert, M. E. Chem. Commun. 2002, 2610. (f) Bedford, R. B.;
Cazin, C. S. J.; Hazelwood (ne´e Welch), S. M. Chem. Commun. 2002, 2608.
(g) Albisson, D. A.; Bedford, R. B.; Lawrence, S. E.; Scully, P. N. Chem.
Commun. 1998, 2095. (h) Albisson, D. A.; Bedford, R. B.; Scully, P. N.
Tetrahedron Lett. 1998, 39, 9793.
(8) (a) Aydin, J.; Kumar, K. S.; Sayah, M. J.; Wallner, O. A.; Szabo´,
K. J. J. Org. Chem. 2007, 72, 4689. (b) Szabo´, K. J. SynLett. 2006, 811.
(c) Wallner, O. A.; Olsson, V. J.; Eriksson, L.; Szabo´, K. J. Inorg. Chim.
Acta 2006, 359, 1767. (d) Baber, R. A.; Bedford, R. B.; Betham, M.; Blake,
M. E.; Coles, S. J.; Haddow, M. F.; Hursthouse, M. B.; Orpen, A. G.;
Pilarski, L. T.; Pringle, P. G.; Wingad, R. L. Chem. Commun. 2006, 3880.
(9) (a) Sokolov, V. I.; Bulygina, L. A.; Borbulevych, O.Ya.; Shishkin,
O. V. J. Organomet. Chem. 1999, 582, 246. (b) Bulygina, L. A.; Sokolov,
V. I. Russ. Chem. Bull. 1998, 47, 1235.
Previously, it was reported that the BINOL-derived bis(pho-
sphites) undergo partial racemization at temperatures above 60
°C.8a This report somewhat contradicts the following data: (i)
high optical yields in enantioselective transition metal-catalyzed
reactionsat45-120°CwiththeBINOL-derivedligands;3a,4a,5a,6c,21
(ii) racemization of BINOL22 and its monoacylated derivatives23
(10) (a) Dupont, J.; Consorti, C. S.; Spencer, J. Chem. ReV. 2005, 105,
2527. (b) Dunina, V. V.; Gorunova, O. N. Russ. Chem. ReV. 2004, 73,
309. (c) Bedford, R. B.; Hazelwood (ne´e Welch), S. M.; Limmert, M. E.;
Albisson, D. A.; Draper, S. M.; Scully, P. N.; Coles, S. J.; Hursthouse,
M. B. Chem.-Eur. J. 2003, 9, 3216.
(11) Bedford, R. B.; Hazelwood, S. M.; Limmert, M. E.; Brown, J. M.;
Ramdeehul, Sh.; Cowley, A. R.; Coles, S. J.; Hursthouse, M. B. Organo-
metallics 2003, 22, 1364.
(12) Despite phosphite HL’s use in catalysis being mentioned,6c its
synthesis, characteristics, and spectral data were not reported.
(13) Baker, M. J.; Pringle, P. G. Chem. Commun. 1991, 1292.
(14) Fuji, K.; Kinoshita, N.; Tanaka, K.; Kawabata, T. Chem. Commun.
1999, 2289.
(19) (a) Dunina, V. V.; Razmyslova, E. D.; Gorunova, O. N.; Livantsov,
M. V.; Grishin, Yu. K Tetrahedron: Asymmetry 2005, 16, 817. (b) Dunina,
V. V.; Zalevskaya, O. A.; Potapov, V. M. Zh. Obshch. Khim. (Russ.) 1983,
53, 468. [Russ. J. Gen. Chem. 1983, 53 (Engl. Transl.)]
(20) (a) Gu¨l, N.; Nelson, J. H. Organometallics 2000, 19, 91. (b)
¨
(15) Dussault, H. D.; Woller, K. R. J. Org. Chem. 1997, 62, 1556.
(16) (a) Tune, D. J.; Werner, H. HelV. Chim. Acta 1975, 58, 2240. (b)
Ahmed, N.; Ainscough, E. W.; James, T. A.; Robinson, S. D. Dalton Trans.
1973, 1151.
(17) Albinati, A.; Affolter, S.; Pregosin, P. S. Organometallics 1990,
9, 379.
(18) (a) Tanase, A. D.; Frey, G. D.; Herdtweck, E.; Hoffmann, St. D.;
Herrmann, W. A. J. Organomet. Chem. 2007, 692, 3316. (b) Bedford, R. B.;
Betham, M.; Coles, S. J.; Norton, P. N.; Lo´pez-Sa´ez, M.-J. Polyhedron
2006, 25, 1003.
Herrmann, W. A.; Brossmer, C.; Reisinger, C.-P.; Riermeier, T. H.; Ofele,
K.; Beller, M. Chem.-Eur. J. 1997, 3, 1357. (c) Fuchita, Y.; Nakashima,
M.; Hiraki, K.; Kawatani, M.; Ohnuma, K. Dalton Trans. 1988, 785.
(21) Duursma, A.; Lefort, L.; Boogers, J. A. F.; de Vries, A. H. M.; de
Vries, J. G.; Minnaard, A. J.; Feringa, B. L. Org. Biomol. Chem. 2004, 2,
1682.
˘
(22) Meca, L.; Reha, D.; Havlas, Zd. J. Org. Chem. 2003, 68, 5677,
and references therein.
(23) Albrow, V.; Biswas, K.; Crane, A.; Chaplin, N.; Easun, T.; Gladiali,
S.; Lygo, B.; Woodward, S. Tetrahedron: Asymmetry 2003, 14, 2813.

Optically ActiVe Phosphapalladacycle
Organometallics, Vol. 28, No. 2, 2009 427
Scheme 4
Figure 1. Mutual arrangement of NH and aromatic protons in two
geometric isomers of valinate derivative (Sa,RC)-4a.
at much higher temperature (220-280 °C); and (iii) reported
mechanistic pathways24 for racemization are inapplicable in our
case. Consequently, we studied whether palladacycle (Sa)-1a
kept the enantiopurity of the starting diol after C-H bond
activation in boiling toluene (∼110 °C).
with the P1 atom (5JHP 5.6 and 2.6 Hz, respectively), and (iii)
1
4
2
only one of the two protons, H(6′′), has a rather large JHP
constant (8 Hz) with the P2 atom of the PPh3 ligand. The signals
The enantiopurity of the dimer (Sa,Sa)-1 was determined by
31P NMR spectroscopy after its chiral derivatization in situ with
the (RC)-valinate auxiliary ligand (Scheme 4). The 31P NMR
spectrum of (Sa,RC)-4a contains only one singlet at δ 148.03
ppm, while two singlets at δ 148.07 and 147.73 ppm were found
in the spectrum of a mixture of two diastereomers, (Sa,RC/Ra,RC)-
4a,b, prepared in a similar way from the dimer rac-1. Thus,
the optically active dimer (Sa,Sa)-1a completely retained the
enantiomeric composition of starting (Sa)-BINOL, confirming
the possibility of direct cyclopalladation of chiral BINOL-
derived ligands without decrease in their enantiomeric purity.
Spectral Studies of Cyclopalladated Complexes. The signal
assignment in the 1H spectra of ligand HL and CPCs 1-4 was
performed using homo- and heteronuclear decoupling, COSY
of the 1,1′-binaphthyl moiety were identified starting from the
4
1
JHP constant values for the H(3)/H(3′) protons (0.9 and 1.2
Hz, respectively).
The signals at δ 1.69 and 2.10 ppm in the 1H NMR spectrum
of the valinate derivative (Sa,RC)-4a were assigned to the NHeq
3
and NHax protons using the correlation of the JHNC H values
R
(4.4 and 7.2 Hz, respectively) with the dihedral angles HNCRH
(+44.67° and +161.84°, respectively, DFT data). The trans-
(N,C)-configuration of complex 4a can be supported by the
following data: (i) the signal of the H(6′′) proton was shifted
low-field (δ 7.87 ppm) due to anisotropy of the carboxylate
oxygen (Figure 1); it was confirmed by DFT calculation of the
chemical shifts and the H(6′′) · · · O(CO) distance (2.31 Å, cf.
ref 28); (ii) DFT calculations for both isomers predict significant
dipole-dipole interactions due to a short H(6′′) · · · NHeq distance
(2.22 Å) only for the alternative cis(N,C) isomer (it was not
detected); and (iii) the trans(N,C)-configuration seems to be
preferable with respect to the “transphobia” concept.27a,29
DFT calculations were performed for trans(N,C) and
cis(N,C) isomers of (Sa,RC)-4a and (Ra,RC)-4b diastereomers of
the valinate derivative (Figure 2, Table 1).30 They provided the
following data: (i) for both diastereomers 4a,b the trans(N,C)
geometry is more preferable than the cis(N,C) (∆E0 2.33 and
2.57 kcal/mol, respectively); (ii) both diastereomers demonstrate
preference for the λ(RC)-conformation of the valinate N,O-ring;31
1
and NOE techniques, DFT structure, and H NMR spectra
calculations for the complexes 3 and 4a,b.
The chemical shift value in the 31P{1H} NMR spectra of
ligand HL (δ 145.1 ppm) is typical for the BINOL-derived
mono-13,15 and bis-phosphites.8c,d,13,25 The 31P{1H} NMR spectra
of the dimers rac-1 and (Sa,Sa)-1a contain four or two broadened
singlets, respectively, which is indicative of their existence as
mixtures of anti and syn isomers. The 31P{1H} NMR spectrum
of the mononuclear adduct 3 consists of two doublets at δ 149.9
and 17.66 ppm assigned to the phosphorus atoms of the PC-
palladacycle (P1) and auxiliary phosphane PPh3 (P2), respec-
tively. The value of the constant 2JPP 45.2 Hz is an unambiguous
evidence of its cis(P,P)-geometry,26 which is typical for
phosphite palladacycles.10c,16b,17,18b,27
(28) Bondi, A. J. Phys. Chem. 1964, 68, 441.
(29) (a) Vicente, J.; Abad, J.-A.; Mart´ınez-Viviente, E. Organometallics
2002, 21, 4454. (b) Vicente, J.; Arcas, A.; Bautista, D.; de Arellano, M. C. R.
J. Organomet. Chem. 2002, 663, 164. (c) Vicente, J.; Arcas, A.; Bautista,
D.; Jones, P. G. Organometallics 1997, 16, 2127.
1
The H NMR spectrum of adduct 3 confirms its cyclopalla-
dated structure. The metalation at the ortho-C-H bond of the
2,4-di-tert-butyl-substituted phenyl ring is supported by the
presence of only two one-proton signals at δ 8.57 (ddd) and
(30) The parameters used for discussion of the conformation of the
valinate N,O-chelate ring and PC-palladacycle were the same as described
below for the X-ray data discussion.
(31) Hawkins, C. J. Absolute Configuration of Metal Complexes; Wiley-
Interscience: New York, 1971.
(32) Hursthouse, M. B.; Gelbrich, T.; Bedford, R. B. Private com-
munication, 2003 (IPOLUU).
(33) Bedford, R. B.; Betham, M.; Coles, S. J.; Frost, R. M.; Hursthouse,
M. B. Tetrahedron 2005, 61, 9663.
3
7.18 ppm (dd) without a JHH coupling constant. Their assign-
ment to H(6′′) and H(4′′) protons, respectively, was based on
the following arguments: (i) the most low-field position of the
first signal due to the influence of the adjacent chloride
anisotropy [H(6′′) · · · Cl distance is equal to 2.49-2.66 Å, DFT
and X-ray data]; (ii) both protons have a spin-spin coupling
(34) Mahalakshmi, L.; Krishnamurthy, S. S.; Nethaji, M. Curr. Sci. 2002,
83, 870 (HUXHIR).
(35) Miyazaki, F.; Yamaguchi, K.; Shibasaki, M. Tetrahedron Lett. 1999,
40, 7379 (GACYUE).
(36) Nomenclature of Inorganic Chemistry. Recommendations 1990;
International Union of Pure and Applied Chemistry; Leigh, G. J., Ed.;
Blackwell Scientific Publications: Oxford, 1990.
(37) Here and later on, the base of the envelope was determined using
the minimal value of the intrachelate torsion angle.
(38) (a) Ayscough, A. P.; Costello, J. F.; Davies, S. G. Tetrahedron:
Asymmetry 2001, 12, 1621. (b) Dance, I.; Scudder, M. Dalton Trans. 2000,
1579. (c) Costello, J. F.; Davies, S. G. J. Chem. Soc., Perkin Trans. 2 1999,
465. (d) Costello, J. F.; Davies, S. G. J. Chem. Soc., Perkin Trans. 2 1998,
1683. (e) Garner, S. E.; Orpen, A. G. J. Chem. Soc., Dalton Trans. 1993,
533.
(24) (a) Jur´ıcˇek, M.; Brath, H.; Kasa´k, P.; Putala, M. J. Organomet.
Chem. 2007, 692, 5279. (b) Kasa´k, P.; Brath, H.; Dubovska´, M.; Jur´ıcˇek,
M.; Putala, M. Tetrahedron Lett. 2004, 45, 791.
(25) Ini, S.; Oliver, A. G.; Tilley, T. D.; Bergman, R. G. Organometallics
2001, 20, 3839.
(26) (a) Phosphorus-31 NMR Spectroscopy in Stereochemical Analysis;
Verkade, J. G., Quin, J. G., Eds.; VCH: Weinheim, 1987. (b) Pregosin,
P. S.; Kunz, R. W. 31P and 13C NMR of transition metal phosphine
complexes. In NMR Basic Principles and Progress Grundlagen and
Fortschritte, Bd. 16; Diel, P., Fluck, E., Kosfeld, R., Eds.; Springer-Verlag:
New York, 1979.
(27) (a) Dunina, V. V.; Gorunova, O. N. Russ. Chem. ReV. 2005, 74,
871. (b) Albinati, A.; Affolter, S.; Pregosin, P. S. J. Organomet. Chem.
1990, 395, 231.
(39) Sharp, J. T.; Gosney, I.; Rowley, A. G. Practical Organic
Chemistry. A student handbook of techniques; London, 1989.

428 Organometallics, Vol. 28, No. 2, 2009
Dunina et al.
Figure 2. DFT-calculated structures for the more stable conformers of trans(N,C) (a, c) and cis(N,C) isomers (b, d) of (Sa,RC)-4a (a, b) and
(Ra,RC)-4b diastereomers (c, d) in the gas phase.
Table 1. Selected Parameters of Two Geometric Isomers of Each of Diastereomeric Valinate Derivatives (Sa,RC)-4a and (Ra,RC)-4b (DFT data).
N,O-chelate ringa
PC-palladacycle
coordination sphere
geometry (N,C)
confor-
mation
confor-
mation
b
b
∆E0, kcal/mol
ꢀav
ONCRC(O)
ꢀav
C1POC2
diastereomer (Sa,RC)-4a
+10.97°
c
trans-4a
cis-4a
0.10
2.43
18.55°
17.62°
λ
λ
0.71°
11.93°
+0.60°
+4.64°
-
λ
+10.61°
diastereomer (Ra,RC)-4b
+10.03°
c
trans-4b
cis-4b
0.00
2.57
16.87°
17.30°
λ
λ
2.25°
9.52°
-1.43°
-3.62°
-
δ
+12.83°
a The N,O-chelate ring in all isomers exists in the λ-conformation with equatorial disposition of the i-Pr group. b The average magnitude of the
absolute values of intrachelate torsion angles (ꢀav) was chosen to characterize the nonplanarity extent of the N,O-chelate ring or PC-palladacycle. c The
PC-palladacycle conformation has to be considered as a nontwisted one.
(iii) the PC-palladacycle’s nonplanarity is substantial in the
complexes cis(N,C)-4a,b (ꢀav ) 11.93° and 9.52°, respectively),
whereas their trans(N,C) isomers contain a nearly planar
metallacycle (ꢀav ) 0.71° and 2.25°); (iv) the PC-palladacycles
in cis(N,C) isomers of (Sa,RC)-4a and (Ra,RC)-4b exist in
opposite envelope-like λ- and δ-conformations, respectively, in
accordance with the configuration of the dioxaphosphepine
moiety; and (v) the palladium coordination environment is
square-planar, with torsion angles P · · · C1 · · · O · · · N < 2.6°.
established unambiguously by the X-ray diffraction study of
the latter. The molecular structure of complex 3 is presented in
Figure 3; selected bond lengths and angles are given in Table
2; its structural and stereochemical peculiarities are discussed
using the (Sa)-enantiomer as an example. To follow the chirality
transfer and to clarify the influence of the bulky 1,3,2-
dioxaphosphepine ring, the structure of complex 3 was compared
with those of its pincer PCP-analogue Ia (R ) R′ ) H) and
known achiral phosphite PC-CPCs (Chart 2).
X-ray Diffraction Study of the Phosphane Adduct
rac-3. The cyclopalladated structure of dimer 1 and the cis(P,P)-
geometry of its mononuclear phosphane derivative rac-3 were
The Pd-C bond length (2.072 Å) in complex 3 is close to
those of known analogues V and VII with trans(P2,C)-
configuration (2.084-2.064 Å). The length of the endo-cyclic
Pd-P1 bond in adduct 3 (2.152 Å) falls in the range 2.142-2.177
Å, typical for other triarylphosphite complexes bearing bridged
(IIIa-d) or terminal (V, VII) chloride on the P1-Pd-Cl
diagonal. The Pd-Cl bond in complex 3 (2.381 Å) is weakened
to some extent compared to that in mononuclear analogues V
and VII (2.349-2.319 Å); however, it is stronger than the
(µ)Cl-Pd bond trans-disposed to the phosphite P-donor atom
in dimers IIIa-d and IIb (2.390-2.419 Å). The exo-cyclic
Pd-P2 bond length in adduct 3 (2.357Å) falls in the range of
(40) Mononuclear pyridine adduct 2 partially decomposed on the silica
to give the dimer 1 (Rf 0.98).
(41) Signal is overlapped with that of the ortho-PPh protons.
(42) Partial decomposition of valinate complexes 4a,b on silica was
observed, resulting in formation of dimer 1 (Rf 0.90).
(43) Perdev, J. P.; Burke, K.; Ernzerhof, M. Phys. ReV. Lett. 1996, 77,
3865.
(44) Laikov, D. N. Chem. Phys. Lett. 2005, 416, 116.
(45) Stivens, W. J.; Bash, H.; Jasien, P. Can. J. Chem. 1992, 70, 612.
(46) (a) Schreckenbach, G; Ziegler, T. Int. J. Quantum Chem. 1997,
61, 899. (b) Schreckenbach, G; Ziegler, T. J. Phys. Chem. 1995, 99, 606.

Optically ActiVe Phosphapalladacycle
Organometallics, Vol. 28, No. 2, 2009 429
Chart 2
this parameter’s values (2.340-2.405 Å) found for analogues
IVb, V, and VII with the P2-Pd-C diagonal.
angle P1 · · · C · · · Cl · · · P2 (+15.48°) connecting four metal-
bonded donor atoms (Figure 4).
The square-planar coordination environment of the palladium
atom in complex 3 reveals a marked tetrahedral distortion
(C1Pd1P1/Cl1Pd1P2 14.83°), which exceeds that for the majority
of phosphite PC-CPCs (0.81-5.76°), including those reported
for the sterically congested compounds IIIb,d, VIc, and VII
(8.36-13.45°). According to the “skew-line convention”36 the
configuration of the pseudo-tetrahedron in adduct 3 may be
defined as Λ on the basis of the positive sign of the torsion
The PC-palladacycle in complex 3 has an envelope-like
conformation37 with P1O1C2C1 atoms coplanar within 0.0344
Å and the palladium atom deviating from their plane by 0.587
Å. The nonplanarity of the PC-palladacycle is rather high, with
average absolute values of intrachelate torsion angles (ꢀav) equal
to 16.80°. Only three sterically encumbered analogues possess
a palladacycle of comparable (V) or more pronounced (IIId
and VIb) puckering extent (ꢀav ) 15.19-21.08°), while in other
CPCs the palladacycle is rather flattened (ꢀav ) 1.16-10.29°).
The envelope-like conformation of the palladacycle in adduct
3 is twisted, with the negative torsion angle C1 · · · P1-O1-C2
(-5.48°) determining its δ(Sa)-stereochemistry.36
The (Sa)-BINOL-derived dioxaphosphepine ring in complex
3 is highly puckered (ꢀav 42.35°); it adopts the δ(Sa) conforma-
tion ( O2 · · · O3-C26 · · · C16 ) -28.59°). These characteristics
are similar to those reported for phosphepine rings of the PCP-
analogue (Ra)-Ia (ꢀav ) 44.12° and 46.03°) with the same λ(Ra)
relationship between axial and conformational chirality.
The P-configuration of the PPh3 propeller in adduct (Sa)-3
was determined by a known method38 (ωav 38.6°). The
calculated ωi values for three PPh groups reveal dependence
on their disposition regarding the BINOL-derived phosphepine
ring: ωA, ωB and ωC values are equal to 66.8°, 33.7°, and 15.4°,
respectively.
The comparative analysis of X-ray data for complex 3 and
its analogues has shown that the introduction of bulky substit-
uents, including a dioxaphosphepine ring, to the structure of
phosphite CPCs results in an increase in the tetrahedral distortion
of the coordination sphere and palladacycle’s puckering.
DFT Investigation of the Phosphane Adduct (Sa)-3. To
estimate the influence of the crystal packing on the structure
and stereochemistry of complex 3, we have performed a DFT
study of its (Sa)-enantiomer (Figure 5). The DFT data confirmed
the tetrahedral distortion of the metal coordination sphere
Figure 3. Molecular structure and numbering scheme of the (Sa)-
enantiomer of the phosphane derivative rac-3. The dichloroethane
solvate molecules are omitted for clarity; thermal ellipsoids are
given for 50% probability.

430 Organometallics, Vol. 28, No. 2, 2009
Dunina et al.
Table 2. Comparison of the Experimental and DFT-Calculated Values of the Selected Bond Lengths (Å) and Bond Angles (deg) for Phosphane
Adduct rac-3
bond lengths (l)
bond angles (φ)
bond
X-ray
DFT
∆l
angle
X-ray
DFT
∆φ
Pd(1)-C(1)
Pd(1)-P(1)
Pd(1)-P(2)
Pd(1)-Cl(1)
P(1)-O(3)
P(1)-O(1)
P(1)-O(2)
O(1)-C(2)
O(2)-C(16)
O(3)-C(26)
C(1)-C(2)
C(1)-C(6)
C(2)-C(3)
C(3)-C(4)
C(4)-C(5)
C(5)-C(6)
2.072(3)
2.1517(9)
2.3567(9)
2.3813(8)
1.588(2)
1.588(2)
1.609(2)
1.421(3)
1.406(4)
1.414(3)
1.387(4)
1.395(4)
1.398(4)
1.392(4)
1.391(4)
1.384(4)
2.097
2.180
2.409
2.360
1.635
1.654
1.628
1.416
1.391
1.402
1.399
1.398
1.407
1.401
1.402
1.400
0.025
0.028
0.052
-0.022
0.047
0.066
0.019
-0.005
-0.015
0.012
0.022
0.003
0.009
0.009
0.011
0.016
C(1)-Pd(1)-P(1)
C(1)-Pd(1)-P(2)
P(1)-Pd(1)-P(2)
C(1)-Pd(1)-Cl(1)
P(1)-Pd(1)-Cl(1)
P(2)-Pd(1)-Cl(1)
O(3)-P(1)-O(1)
O(3)-P(1)-O(2)
O(1)-P(1)-O(2)
O(3)-P(1)-Pd(1)
O(1)-P(1)-Pd(1)
O(2)-P(1)-Pd(1)
C(2)-O(1)-P(1)
C(16)-O(2)-P(1)
C(26)-O(3)-P(1)
C(2)-C(1)-Pd(1)
C(6)-C(1)-Pd(1)
76.28(9)
169.84(9)
104.31(3)
95.22(9)
167.02(3)
85.81(3)
103.47(12)
104.03(11)
100.20(12)
120.97(9)
111.13(9)
114.56(9)
110.33(18)
115.84(19)
120.15(19)
119.6(2)
77.40
173.25
105.94
92.94
169.12
84.20
103.00
101.56
98.07
121.93
109.67
119.06
110.95
119.32
119.68
118.99
122.96
1.12
3.41
1.63
-2.28
2.10
-1.61
-0.47
-2.47
-2.13
0.96
-1.46
4.50
0.62
3.48
-0.47
-0.61
-0.14
123.1(2)
( P1 · · · C · · · Cl · · · P2 ) +8.69°) and the same Λ-configuration
of the pseudo-tetrahedron (Figure 6a). The calculated nonpla-
narity extent of the PC-palladacycle (ꢀav ) 15.41°) is very close
to that found for the crystal with the same δ-conformation
( C1 · · · P1-O1-C2 ) -6.15°, Figure 6b). The (Sa)-dioxaphos-
phepine ring possesses a similar puckering extent (ꢀav 41.58°)
P-configuration of the PPh3 propeller (ωav ) 41.20°) and similar
dependence of PPh group orientation on their disposition
regarding the phosphepine ring (ωA, ωB, and ωC values are equal
to 68.74°, 35.14°, and 19.73°, respectively, Figure 6d).
From the comparison between the calculated parameters for
two derivatives of phosphite PC-palladacycle, 3 and 4a, one
can see that bulkiness of the auxiliary ligand has a considerable
impact on the overall stereochemistry of the complexes. Thus,
phosphane adduct 3 reveals a more pronounced tetrahedral
distortion and a more puckered PC-palladacycle conformation
compared to the less sterically congested valinate adduct 4a.
Such a difference allows one to assume that chirality transfer
from the phosphite palladacycle to sterically encumbered
auxiliary ligands may be rather efficient due to participation of
two additional chirality elements (pseudo-tetrahedron and
twisted conformation) in this process.
and the same δ(Sa)-conformation ( O2 · · · O3-C26 · · · C16
)
-27.89°, Figure 6c). The calculated rotameric state of the PPh3
ligand corresponds to that found for the crystal, with the same
Conclusions
We have described the preparation of the first optically active
PC-palladacycle with a phosphorus atom in an axially chiral
environment. The possibility of direct C-H bond activation in
the (Sa)-BINOL-derived phosphite under thermal conditions
(∼110 °C) without decrease its enantiopurity was confirmed
by 31P NMR spectroscopy after chiral derivatization of dimer
(Sa,Sa)-1 with the (RC)-valinate auxiliary ligand. The X-ray
diffraction data and DFT calculations performed for the phos-
phane derivative (Sa)-3 showed that axial chirality of the (Sa)-
Figure 4. Correlation of the skew-line disposition with torsion angle
sign.
Figure 5. DFT-calculated structure for the phosphane derivative
rac-3 in the gas phase.
Figure 6. Chirality elements in the phosphane derivative rac-3.

Optically ActiVe Phosphapalladacycle
Organometallics, Vol. 28, No. 2, 2009 431
0.107 mmol) and stirred for 15 min to give the homogeneous
solution of the pyridine adduct 2 (Rf 0.30; toluene/acetone, 1:1),40
which was evaporated. In the course of the complex rac-2 eluation
through the flash column loaded with silica (h ) 13 cm, d ) 2 cm;
eluents: toluene/light ligroin, 2:1, then toluene and toluene/acetone,
5:1) the complete decomplexation of auxiliary pyridine ligand took
place to afford purified dimer rac-1 in a yield of 43% (0.0533 g,
0.0402 mmol) as a colorless, amorphous powder: mp (dec) 247
°C; Rf 0.5 (toluene/hexane, 1:1). Anal. Calcd for C68H64P2O6Pd2Cl2:
C, 61.73; H, 4.89. Found: C, 61.44; H, 5.05. 31P{1H} NMR: δ
138.45 (s) and 138.54 (s) (86%); 140.75 (s) and 140.81 (s) (14%).
BINOL fragment causes both the seven-membered 1,3,2-
dioxaphosphepine ring and the five-membered PC-palladacycle
to adopt the δ-conformation. The (Sa)-BINOL moiety in
complex (Sa)-3 also triggers both the Λ-configuration of the
pseudo-tetrahedral palladium coordination environment and the
P-rotameric state of the PPh3 propeller.
Experimental Section
General Procedures. The 1H and 31P NMR spectra were
recorded on Varian VXR-400 and Bruker DPX-400 spectrometers
(Sa,Sa)-Di-µ-chlorobis[(1,1′-binaphthyl-2,2′-diyl)(2,4-di-tert-bu-
tylphenyl)phosphite-C,P]dipalladium(II), (Sa,Sa)-1a. A solution of
Pd(PhCN)2Cl2 (0.0465 g, 0.1212 mmol) and phosphite (Sa)-HL
(0.0631 g, 0.1212 mmol) in toluene (2 mL) was refluxed for 7 h
under stirring. The palladium black formed was removed by
filtration, and mother liquid was evaporated. The residue was
purified using flash-column chromatography (h ) 13 cm, d ) 2
cm; eluents: toluene/petroleum ether, 1:1, then toluene, and toluene/
acetone, 10:1) to give dimer (Sa,Sa)-1a in a yield of 40% (0.0320
g, 0.0242 mmol) as a colorless, amorphous powder: mp (dec) 230
°C; Rf 0.5 (toluene/hexane, 1:1). Anal. Calcd for C68H64P2O6Pd2Cl2:
C, 61.73; H, 4.89. Found: C, 61.49; H, 4.88. 31P{1H} NMR: δ
1
operating at the frequencies 400 and 161.9 MHz for H and 31P
nuclei, respectively. The measurements were carried out at ambient
temperature in CDCl3 solutions (unless otherwise indicated). The
chemical shifts are reported in δ-scale in parts per million relative
to TMS as an internal standard for 1H NMR and relative to H3PO4
as an external reference for the 31P NMR spectra. The signal
assignment was based on homo- and heteronuclear decoupling,
COSY, and NOE experiments. Optical rotations were measured
on a Perkin-Elmer (model 341) polarimeter in 0.5 dm cells at 25
°C. Melting points were measured on an Electrothermal IA 9000
series device in sealed capillaries. All reactions were conducted
under argon using TLC control on Silufol. All manipulations with
the free phosphite were carried out under dry purified argon in
deoxygenated and dried solvents using Schlenk techniques. Com-
pound purification was performed using a short, dry column39 or
flash chromatography on silica gel (60, Fluka).
1
140.68 (s, 16%), 138.43 (s, 84%). H NMR: δ 1.12 (s, But), 1.20
(s, But), 7.10 (app. br s), 7.14-7.19 (m), 7.24-7.26 (m), 7.28-7.29
(m), 7.31-7.35 (m), 7.37-7.42 (m), 7.49-7.53 (m), 7.81 (br d),
7.97 (app. br d), 8.06 (br d).
Racemic Chloro[(1,1′-binaphthyl-2,2′-diyl)(2,4-di-tert-butylphe-
nyl)phosphite-C,P](triphenylphosphane)palladium(II), rac-3. A
suspension of the racemic dimer 1 (0.0182 g, 0.0138 mmol) in
toluene (1.5 mL) was treated with triphenylphosphane (0.0072 g,
0.0275 mmol). The reaction mixture was stirred for 30 min at rt
under TLC control and evaporated, and the residue was purified
using dry column chromatography39 (h ) 5 cm, d ) 4 cm; eluents:
toluene and then toluene/acetone, 5:1). After 2-fold recrystallization
from dichloromethane/hexane mononuclear derivative rac-3 was
obtained in a yield of 60% (0.020 g, 0.0216 mmol) as a light-yellow
crystalline solid: mp (dec) 225 °C; Rf 0.73 (toluene/acetone, 10:1).
Anal. Calcd for C52H47P2O3PdCl: C, 67.60; H, 5.14. Found: C,
67.43; H, 5.25. The monocrystals for X-ray investigation were
grown from 1,2-dichloroethane/pentane using vapor diffusion
technique. 31P{1H} NMR (CD2Cl2): δ 17.66 (d, 2JPP 45.2), 149.91
Toluene was dried over CaCl2, refluxed over Na, and then
distilled under argon. Anhydrous MeOH was prepared by distillation
from MeONa. Chloroform and dichloromethane were passed
through a short Al2O3 column and distilled under argon. Hexane
and light petroleum ether were distilled from Na under argon. CDCl3
and CD2Cl2 (from Aldrich) were distilled from CaH2 under argon
just before using. Palladium(II) chloride and acetate and (RC)-valine
(from Aldrich), Pd(PhCN)2Cl2 (from Merck), and (Sa)-1,1′-binaph-
thyl-2,2′-diol (from Fluka) were used as received. PPh3 and racemic
BINOL (from Aldrich) were purified by 2-fold recrystallization from
benzene/hexane and acetone, respectively. PCl3 was distilled under
argon. Et3N was distilled from Na under argon before using. 2,4-
Di-tert-buthylphenol (from Aldrich) was recrystallized two times
from light petroleum ether and dried under P2O5 and paraffin in
Vacuo.
(d, 2JPP 45.2). 1H NMR (CD2Cl2): δ 1.14 (s, 9H, But), 1.40 (s, 9H,
(Sa)-(1,1′-Binaphthyl-2,2′-diyl)(2,4-di-tert-butylphenyl)phos-
5
But), 7.01-7.08 (m, 4JHP 2.0, 6H, meta-PPh), 7.10-7.15 (m, JHP
2
2
phite, (Sa)-HL. (Sa)-HL was prepared by a slightly modified known
2.0, 3H, para-PPh), 7.17 (dd, 5JHP 2.6, JHH 2.1, 1H, H4′′), 7.21 (d,
4
method8d,10c,11 and chromatographically purified. [R]D +103.5
25
1
3JHH 8.6, 1H, H8/H8′), 7.22-7.28 (m, 2H, H7/H7′ and H8′/H8), 7.33
(c 1.31, CH2Cl2). Anal. Calcd for C34H33PO3: C, 78.43; H, 6.40.
41
(m, 1H, H7′/H7), 7.35-7.41 (m, 3JHP 10.9, 6H, ortho-PPh), 7.38
1
Found: C, 78.60; H, 6.48. 31P{1H} NMR: δ 145.07 (s). H NMR:
2
(dd, JHH 8.8, JHP 0.9, 1H, H3/H3′), 7.46 (dd, JHH 8.9, JHP 1.2,
3
4
3
4
δ 1.32 (s, 9H, But), 1.37 (s, 9H, But), 7.19 (dd, 3JHH 8.3, 4JHH 2.5,
1H, H5′′), 7.24 (d, 3JHH 8.3, 1H, H6′′), 7.27 (ddd, 3JHH 8.3, 3JHH 7.0,
1
1
1H, H3′/H3), 7.48-7.52 (m, 1H, H6/H6′), 7.50-7.54 (m, 1H, H6′/
H6), 7.58 (d, JHH 8.8, 1H, H4/H4′), 7.84 (d, JHH 8.2, 1H, H5/H5′),
3
3
3
3
4
4JHH 1.3, 1H, H7/H7′), 7.29 (ddd, JHH 8.3, JHH 6.9, JHH 1.5, 1H,
7.98 (d, JHH 8.2, 1H, H5′/H5), 8.03 (d, JHH 8.9, 1H, H4′/H4), 8.47
3
3
H7′/H7), 7.39 (d, 4JHH 2.5, 1H, H3′′), 7.40 (d, 3JHH 8.3, 1H, H8/H8′),
4
4
4
(ddd, JHP 5.6, JHP 8.0, JHH 2.2, 1H, H6′′).
7.42 (d, JHH 8.3, 1H, H8′/H8), 7.43 (ddd, JHH 8.3, JHH 7.0, JHH
3
3
3
4
1
2
1.3, 1H, H6/H6′), 7.46 (ddd, JHH 8.3, JHH 6.9, JHH 1.3, 1H, H6′/
3
3
4
[{(Sa)-1,1′-Binaphthyl-2,2′-diyl}(2,4-di-tert-butylphenyl)phosphite-
C,P][(RC)-valinato-N,O)palladium(II), (Sa,RC)-4a. The dimer (Sa)-
1a (0.0062 g, 0.0062 mmol) was added to a solution of excess
sodium (R)-valinate (0.0028 g, 0.0248 mmol) in chloroform (2 mL),
and the reaction mixture was stirred at rt for 4 h, filtered, and
evaporated. At this stage 31P{1H} NMR (CDCl3, δ, ppm): 148.03
(s). After recrystallization of the residue from chloroform/hexane
at low temperature diastereomer (Sa,RC)-4a was obtainned in a yield
of 93% (0.0083 g, 0.0115 mmol) as a colorless, finely crystalline
H6), 7.48 (dd, 3JHH 8.8, 4JHP 0.8, 1H, H3/H3′), 7.58 (d, 3JHH 8.8, 1H,
H3′/H3), 7.90 (d, JHH 8.8, 1H, H4/H4′), 7.91 (d, JHH 8.3, 1H, H5/
3
3
H5′), 7.95 (d, JHH 8.3, 1H, H5′/H5), 8.01 (d, JHH 8.8, 1H, H4′/H4).
Racemic (1,1′-binaphthyl-2,2′-diyl)(2,4-di-tert-butylphenyl)phos-
phate. was obtained similarly.
3
3
Racemic Di-µ-chlorobis[(1,1′-binaphthyl-2,2′-diyl)(2,4-di-tert-bu-
tylphenyl)phosphite-C,P]dipalladium(II), rac-1. A solution of
Pd(PhCN)2Cl2 (0.0715 g, 0.186 mmol) in 1,2-dichloroethane (3 mL)
was added to a phosphite HL (0.097 g, 0.186 mmol) and the
homogeneous reaction mixture was refluxed for 9 h under stirring.
The precipitate formed was filtered and dried in Vacuo to give the
crude dimer 1 in a yield of 57% (0.0707 g, 0.0534 mmol) as a
highly insoluble powder. The suspension of the crude dimer rac-1
in dichloromethane (3 mL) was treated with pyridine (0.0085 g,
solid: mp (dec) 228-230 °C, Rf 0.48 (toluene/acetone, 1:1).42 [R]D
25
+155.6 (c 0.25, CHCl3). Anal. Calcd for C39H42PO5NPd: C, 63.11;
H, 5.72; N 1.89. Found: C, 63.09; H, 5.70; N 1.94. 31P{1H} NMR:
δ 148.12 (s). 1H NMR: δ 0.94 (d, 3JHH 7.1, 3H, Me), 1.16 (d, 3JHH
2
3
7.0, 3H, Me), 1.69 (br dd, JHH 11.0, JHNC H 4.4, 1H, NHeq), 2.10
R
(br dd, JHH 11.0, JHNC H 7.2, 1H, NHax), 2.47 (m, 1H, CHMe2),
2
3
R

432 Organometallics, Vol. 28, No. 2, 2009
Dunina et al.
3
3
3
3.40 (ddd, JHCNH 7.2, JHCNH 4.4, JHCCH 6.9, 1H, R-CH), 1.27 (s,
X-ray Diffraction Study of Phosphane Derivative rac-3.
Crystal of adduct 3 (C56H55Cl5O3P2Pd, M ) 1121.59), triclinic,
9H, But), 1.33 (s, 9H, But), 7.23 (dd, JHP 3.5, JHH 2.1, 1H, H4′′),
5
4
7.38-7.43 (m, 2H, H7/H7′ and H8/H8′), 7.46 (ddd, JHH 8.7, JHH
space group P1, at 100 K, a ) 12.9201(7) Å, b ) 14.3239(8) Å,
3
3
j
6.9, JHH 1.3, 1H, H7′/H7), 7.48 (br d, JHH 8.8, 1H, H3/H3′), 7.53
(d, 3JHH 8.7, 1H, H8′/H8), 7.57 (m, 1H, H6/H6′), 7.63 (ddd, 3JHH 8.3,
3JHH 6.9, 4JHH 1.3, 1H, H6′/H6), 7.72 (app. d, 3JHH 8.8, 4JHP 0.4, 1H,
c ) 16.3593(14) Å, R ) 111.534(2)°, ꢀ ) 106.222(2)°, γ )
4
3
98.2940(10)°, V ) 2598.8(3) Å3, Z ) 2, F(000) ) 1152, dcalc
)
1.433 g · cm-3, µ ) 0.719 mm-1. Unit cell parameters and intensities
of 32 453 reflections were measured with a Bruker SMART APEX2
CCD area detector diffractometer, using graphite-monochromated
Mo KR radiation at 100 K, ꢁ- and ω-scan, θmax ) 29°. Reflection
intensities were integrated using SAINT software,47 and absorption
correction was applied semiempirically using the SADABS pro-
gram. The structure was solved by direct methods and refined by
full-matrix least-squares against F2 in anisotropic approximation
for non-hydrogen atoms. All hydrogen atoms were placed in
geometrically calculated positions, and their positions were refined
in isotropic approximation in a riding model. The crystal of 3
contains two solvate molecules of 1,2-dichloroethane; in one of
them the carbon atoms are disordered over two sites with 3:7
occupancies. All calculations were performed using the SHELXTL
software.48 Final R-factors are equal to R1 ) 0.0517 for 9366
reflections with I > 2σ(I) and wR2 ) 0.0749 for all 14 061
independent reflections. CCDC-677989 contains the supplementary
crystallographic data for this paper. These data can be obtained
free of charge from the Cambridge Crystallographic Data Centre
via www.ccdc.cam.ac.uk/data_request/cif.
H3′/H3), 7.87 (dd, JHP 7.1, JHH 2.1, 1H, H6′′), 8.04 (d, JHH 8.3,
4
4
3
1H, H5/H5′), 8.06 (d, JHH 8.3, 1H, H5′/H5), 8.09 (d, JHH 8.8, 1H,
3
3
H4/H4′), 8.17 (d, JHH 8.8, 1H, H4′/H4).
3
Diastereomer Mixture of [(1,1′-Binaphthyl-2,2′-diyl)(2,4-di-tert-
butylphenyl)phosphite-C,P][(RC)-valinato-N,O)palladium(II), (Sa,RC)-
4a and (Ra,RC)-4b. Dimer rac-1 (0.0157 g, 0.0118 mmol) was added
to a solution of sodium (R)-valinate (0.0029 g, 0.0237 mmol) in
chloroform (2 mL), and the reaction mixture was stirred at rt for
3 h, filtered, and evaporated. At this stage 31P{1H} NMR: δ 147.73
(s), 148.07 (s). After recrystallization of the residue from dichlo-
romethane/hexane at low temperature diastereomer mixture 4a,b
was obtained in a yield of 84% (0.0141 g, 0.0197 mmol) as a
colorless, finely crystalline solid: mp (dec) 235-237 °C, Rf 0.53
(toluene/acetone, 1:1).42 [R]D25 0.00, [R]43625 17.0 (c 0.19, CHCl3).
Anal. Calcd for C39H42PO5NPd: C, 63.11; H, 5.72; N 1.89. Found:
C, 63.07; H, 5.74; N 1.93. 31P{1H} NMR: δ 147.73 (s), 148.05 (s).
Computational Details. All DFT calculations were performed
for the gas phase at the generalized gradient approximation for
the nonempirically constructed PBE functional,43 using the
program package in version PRIRODA-6.44 The one-electron
wave functions were expanded into the extended TZ2P basis
sets44 including the contracted Gauss functions {311/1} for the
hydrogen atoms, {51111/51111/5111} for palladium atom, and
{6,11111/411/11} for all other atoms (carbon, nitrogen, oxygen,
and phosphorus). The relativistic pseudopotential SBK was used
in the known version.45 The energy E0 was calculated taking
into account the zero-point vibration energy in harmonic
approximation. All structures were fully optimized. Corrections
for zero-point energies were calculated in the harmonic ap-
proximation. The 1H NMR spectra were calculated using gauge-
including atomic orbitals (GIAO)46 in the complete electronic
TZ2P basis. The calculated chemical shifts were expressed as
the difference between the shielding of the reference (TMS) and
the complex to be studied. All calculations were performed on
the MVS 15000BM computer cluster at the Joint Supercomputer
Center (JSCC, Moscow).
Acknowledgment. This research was supported partly by
the Presidium Russian Academy of Sciences, grant P1. The
authors thank Dr. I. P. Smoliakova for valuable discussions.
Supporting Information Available: Full crystallographic data
for complex 3 are available as a cif file. Synthesis of phosphites
rac-HL and (Sa)-HL, experimental 1H and 31P NMR spectra, DFT-
1
calculated H chemical shifts, and structures of complexes 4a,b
(in Decart coordinates) are given. These materials are available free
of charge via the Internet at http://pubs.acs.org.
OM800654R
(47) SMART V5.051 and SAINT V5.00, Area detector control and
integration software; Bruker AXS Inc.: Madison,WI, 1998.
(48) Sheldrick, G. M. SHELXTL-97, V5.10; Bruker AXS Inc.: Madison,
WI, 1997.