Complexes of PdCl2 with chiral oximes of α-(o-anisidino) caranone and α-(o-anisidino)pinanone: Synthesis and crystal structures

Article abstract of DOI:10.1007/s11172-013-0378-5

3-(2-Methoxyphenylamino)caran-4-one and 2-(2-methoxyphenylamino)pinan-3-one E-oximes obtained from appropriate natural terpenes were transformed into 1: 1 complexes with PdCl₂. The structures of the complexes were examined by X-ray diffraction.

Full text of DOI:10.1007/s11172-013-0378-5

Russian Chemical Bulletin, International Edition, Vol. 62, No. 12, pp. 2595—2602, December, 2013
2595
Complexes of PdCl2 with chiral oximes of ꢀ(oꢀanisidino)caranone
and ꢀ(oꢀanisidino)pinanone: synthesis and crystal structures
T. E. Kokina,a,b L. A. Glinskaya,a A. M. Agafontsev,b,c E. V. Artimonova,b L. A. Sheludyakova,a
I. V. Korol´kov,a A. V. Tkachev,b,c and S. V. Larionova
aA. V. Nikolaev Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of Sciences,
3 prosp. Akad. Lavrent´eva, 630090 Novosibirsk, Russian Federation.
Fax: +7 (383) 330 9487. Eꢀmail: kokina@niic.nsc.ru
bNovosibirsk National Research State University,
2 ul. Pirogova, 630090 Novosibirsk, Russian Federation
cN. N. Vorozhtsov Novosibirsk Institute of Organic Chemistry, Siberian Branch of the Russian Academy of Sciences,
9 prosp. Akad. Lavrent´eva, 630090 Novosibirsk, Russian Federation.
Fax: +7 (383) 330 9752. Eꢀmail: atkachev@nioch.nsc.ru
3ꢀ(2ꢀMethoxyphenylamino)caranꢀ4ꢀone and 2ꢀ(2ꢀmethoxyphenylamino)pinanꢀ3ꢀone
Eꢀoximes obtained from appropriate natural terpenes were transformed into 1 : 1 complexes
with PdCl2. The structures of the complexes were examined by Xꢀray diffraction.
Key words: synthesis, amino oximes, monoterpenoids, palladium complexes, crystal strucꢀ
ture, optical activity.
The synthesis and study of the properties of metal comꢀ
plexes with optically active hybrid organic ligands derived
from monoterpenoids that are extracted while processing
renewable woodꢀchemical raw materials are of scientific
and applied interest.1—5 Recent extensive development of
the chemistry of PdII complexes with such ligands is due
to the catalytic activity of chiral PdII complexes in various
reactions.6—10 In particular, optically active monoꢀ and
dinuclear PdII complexes with ligands of symmetry C1
and C2 that are ꢀsubstituted oximes of the terpene series
have been found to be catalytically active in stereoselecꢀ
tive cyclopropanation.11 This made it interesting to obtain
and study complexes of PdCl2 with new chiral ligands of
symmetry C1, viz., ꢀamino oximes derived from (+)ꢀ3ꢀ
carene and (–)ꢀꢀpinene.
The goal of the present work was to obtain and study
the structure and optical activity of PdII complexes with
chiral (E)ꢀoximes of (1R,3S,6R)ꢀ3ꢀ(2ꢀmethoxyphenylꢀ
amino)caranꢀ4ꢀone (1) and (1R,2R,5R)ꢀ2ꢀ(2ꢀmethoxyꢀ
phenylamino)pinanꢀ3ꢀone (2)*.
Ligands 1 and 2 were prepared by nitrosochlorination3
of (+)ꢀ3ꢀcarene and (–)ꢀꢀpinene, respectively.
The crystal structure of 1 is made up of acentric moleꢀ
cules. The benzene ring in structure 1 is planar (Fig. 1, a,
Table 1). In agreement with previous data,12 the conforꢀ
mation of the sixꢀmembered carbocycle resembles a halfꢀ
boat (envelope): the C(3) atom deviates from the plane
C(1)C(2)C(4)C(5)C(6) by 0.709(2) Å. The dimethylcyꢀ
clopropane fragment shares the C(1)—C(6) side with this
carbocycle and makes a dihedral angle of 111.0(1) with
the plane C(1)C(2)C(4)C(5)C(6). The angle between the
latter and the plane of the benzene ring is 79.8(1). The
angle at the N(2) atom is 127.4. The crystal structure is
stabilized by Hꢀbonds between molecules 1 united into
"headꢀtoꢀtail" chains along the axis b (see Fig. 1, b).
In structure 2 (Fig. 2, a, Table 2), the benzene ring is
also nearly planar. The sixꢀmembered carbocycle adopts a
"Y" conformation. The angle between the plane of the
benzene ring and the plane C(1)C(2)C(3)C(4)C(5) of this
carbocycle is 31.8(1), which is more than two times smallꢀ
er than an analogous angle in structure 1. In contrast to
ligand 1, the crystal structure 2 is built from ensembles of
two molecules held together by strong hydrogen bonds
O—H...N between two oxime groups along the axis a (see
Fig. 2, b).
* The atomic numbering in the structures shown below was used
to interpret NMR spectra.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2595—2602, December, 2013.
1066ꢀ5285/13/6212ꢀ2595 © 2013 Springer Science+Business Media, Inc.

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Kokina et al.
a
a
H(10)
O(1)
H(10)
C(3)
O(1)
C(17)
N(1)
C(4)
C(13)
C(12)
O(2)
C(16)
N(1)
H(2)
N(2)
C(10)
C(4)
C(5)
C(14)
C(11)
C(2)
C(15)
C(14)
C(3)
C(5)
C(8)
C(7)
C(11)
C(12)
C(8)
C(6)
C(10)
N(2)
C(16)
C(15)
C(2)
C(1)
C(1)
C(6)
C(9)
C(7)
C(9)
O(2)
C(17)
C(13)
b
b
C(17)
O(1´)
O(2)
H(10´)
N(1´)
O(2)
N(1)
H(10´)
N(1´)
C(3´)
O(2´)
O(1)
O(1´)
H(10)
H(10)
N(1)
C(3)
O(1)
O(2)
C(17´)
b
a
Fig. 1. Molecular structure of compound 1 with the thermal
displacement ellipsoids (p = 40%) of the nonꢀhydrogen atoms
(a) and a fragment of a chain made up of hydrogenꢀbonded
adjacent molecules of 1 (b) (O(1´)...O(2), 2.875(2) Å;
O(2)...H(1O´), 2.05(2) Å).
Fig. 2. Molecular structure of compound 2 with the thermal
displacement ellipsoids (p = 40%) of the nonꢀhydrogen atoms (a)
and an ensemble formed by the strong hydrogen bonds O—H...N
between two oxime groups of two molecules of 2 (b)
(O(1´)...N(1), 2.843(2) Å; N(1)...H(1O´), 2.143(2) Å).
Table 1. Selected bond lengths (d) and bond angles () in structure 1
Bond
d/Å
Angle
/deg
Angle
/deg
O(1)—N(1)
O(2)—C(16)
O(2)—C(17)
N(1)—C(4)
N(2)—C(11)
N(2)—C(3)
1.418(2)
1.378(2)
1.426(2)
1.276(2)
1.386(2)
1.458(2)
C(16)—O(2)—C(17)
C(4)—N(1)—O(1)
C(11)—N(2)—C(3)
N(2)—C(3)—C(2)
N(2)—C(3)—C(10)
118.1(1)
112.2(1)
127.4(1)
105.4(1)
111.1(1)
O(2)—C(16)—C(15)
O(2)—C(16)—C(11)
N(1)—C(4)—C(5)
N(1)—C(4)—C(3)
C(2)—C(3)—C(4)
124.9(2)
113.6(1)
125.8(2)
117.2(1)
106.3(1)
Table 2. Selected bond lengths (d) and bond angles () in structure 2
Bond
d/Å
Angle
/deg
Angle
/deg
O(1)—N(1)
O(2)—C(16)
O(2)—C(17)
N(1)—C(3)
N(2)—C(11)
N(2)—C(2)
1.410(2)
1.375(3)
1.406(4)
1.265(2)
1.399(3)
1.487(3)
C(16)—O(2)—C(17)
C(3)—N(1)—O(1)
C(11)—N(2)—C(2)
N(2)—C(2)—C(1)
N(2)—C(2)—C(10)
119.5(3)
112.7(2)
124.2(2)
110.8(2)
111.1(2)
O(2)—C(16)—C(15)
O(2)—C(16)—C(11)
N(1)—C(3)—C(4)
N(1)—C(3)—C(2)
C(3)—C(2)—C(1)
125.4(2)
113.5(2)
124.2(2)
114.8(2)
106.9(2)

Pd complexes with amino oximes of terpenes
Russ.Chem.Bull., Int.Ed., Vol. 62, No. 12, December, 2013
2597
H(10)
The molecular structures 1 and 2 show different conꢀ
figurations of the NH group. In structure 1, the N atom is
sp2ꢀhybridized and the lone electron pair on the pꢀorbital
of the N atom is conjugated with the aromatic fragment, so
the configuration is planar. In structure 2, the conjugation
is disrupted, and the N atom of the NH group has a pyrꢀ
amidal configuration characteristic of sp3ꢀhybridization.
Reactions of PdCl2 with dextrorotatory oxime 1 and
levorotatory oxime 2 in EtOH—acetone give levorotatory
complex 3 and dextrorotatory complex 4, respectively.
The crystal structures of complexes 3 and 4 consist of
mononuclear molecules (Figs 3, 4; Tables 3, 4). The Pd
atom coordinates two N atoms of chelating bidentate
ligands 1 and 2 and two Cl atoms. The coordination reꢀ
sults in closure of the fiveꢀmembered chelate ring PdN2C2.
The Pd—N bond lengths are 1.997(1) and 2.058(1) Å in
O(1)
C(5)
C(4)
C(3)
N(1)
C(8)
C(6)
C(7)
Cl(1)
Pd(1)
C(2)
H(2N)
N(2)
C(9)
C(1)
C(10)
O(2)
Cl(2)
C(11)
C(17)
C(16)
C(12)
C(15)
C(13)
C(14)
C(5)
C(6)
C(8)
C(7)
C(4)
Fig. 4. Molecular structure of compound 4 with the thermal
displacement ellipsoids (p = 40%) of the nonꢀhydrogen atoms.
Pd(1)
C(3)
C(9)
Cl(1)
C(10)
N(2)
complex 3 and 1.991(2) and 2.102(2) Å in complex 4. The
bond between the Pd atom and the oxime N atom is the
shorter one. The Pd—Cl bond lengths differ only slightly
(see Tables 3, 4). The coordination unit PdN2Cl2 is
a distorted square. The chelate ring PdN2C2 adopts an
envelope conformation, with the C(3) (in 3) and C(4)
atom (in 4) deviating from the plane of the other four
atoms by –0.509(2) and 0.648(3) Å, respectively. Strucꢀ
tures 3 and 4 show the fiveꢀmembered ring PdNOHCl
(envelope conformation) formed by an intramolecular
Hꢀbond (O(1)...Cl(1), 3.017(3) (3) and 3.048(3) Å (4)).
In structure 3, the sixꢀmembered carbocycle adopts
a distorted boat conformation: the C(2) and C(5) atoms
C(1)
C(2)
C(12)
H(2N)
C(11)
C(16)
O(2)
C(15)
Cl(2)
C(13)
C(14)
C(17)
Fig. 3. Molecular structure of compound 3 with the thermal
displacement ellipsoids (p = 40%) of the nonꢀhydrogen atoms.
Table 3. Selected bond lengths d and bond angles  in structure 3
Bond
d/Å
Bond
d/Å
Angle
/deg
Angle
/deg
Pd(1)—N(1) 1.997(1)
Pd(1)—N(2) 2.058(1)
Pd(1)—Cl(2) 2.2779(4)
Pd(1)—Cl(1) 2.2978(4)
N(1)—O(1) 1.394(2)
N(2)—C(11) 1.462(2)
N(2)—C(3) 1.531(2)
O(2)—C(16) 1.356(2)
O(2)—C(17) 1.435(2)
N(1)—Pd(1)—N(2)
N(1)—Pd(1)—Cl(2)
N(2)—Pd(1)—Cl(2)
C(11)—N(2)—C(3)
80.7(1) N(1)—Pd(1)—Cl(1)
174.0(1) N(2)—Pd(1)—Cl(1) 170.6(1)
93.5(1) Cl(2)—Pd(1)—Cl(1)
115.2(1)
90.3(1)
95.6(1)
N(1)—C(4)
1.276(2)
Table 4. Selected bond lengths d and bond angles  in structure 4
Bond
d/Å
Bond
d/Å
Angle
/deg
Angle
/deg
Pd(1)—N(1)
Pd(1)—N(2)
1.991(2)
2.102(2)
N(1)—O(1)
N(2)—C(11) 1.465(3)
1.371(2)
N(1)—Pd(1)—N(2)
N(1)—Pd(1)—Cl(2) 173.6(1) N(2)—Pd(1)—Cl(1) 169.9(1)
79.9(1) N(1)—Pd(1)—Cl(1)
90.1(1)
Pd(1)—Cl(2) 2.2639(6) N(2)—C(2)
Pd(1)—Cl(1) 2.2913(6) O(2)—C(16)
1.546(3)
1.360(3)
1.427(3)
N(2)—Pd(1)—Cl(2)
C(11)—N(2)—C(2)
97.1(1) Cl(2)—Pd(1)—Cl(1)
114.9(1)
92.8(1)
N(1)—C(3)
1.282(3)
O(2)—C(17)

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Kokina et al.
are on the same side of the plane C(1)C(3)C(4)C(6), deviꢀ
ating by –0.482(2) and –0.4655(2) Å, respectively.
The dimethylcyclopropane fragment makes an angle of
138.7(1) with the plane C(1)C(3)C(4)C(6) of the sixꢀ
membered carbocycle. The hydrogen atom of the NH
group and the adjacent Me group are cis to each other (see
Fig. 3). In structure 4, the sixꢀmembered carbocycle adopts
a "Y" conformation. Unlike complex 3, structure 4 shows
a transꢀarrangement of the amino H atom and the neighꢀ
boring Me group (see Fig. 4). Obviously, both complexꢀ
ation reactions yield the diastereomer (out of two possible
ones) that is more stable under the chosen experimental
conditions.
Free and coordinated (in complex 3) molecules of
ligand 1 have different structures because of a considerꢀ
able effect produced by the coordination. The sixꢀmemꢀ
bered carbocycle changes its conformation (halfꢀboat 
 distorted boat), and the angle between the planar fragꢀ
ments of this carbocycle and the dimethylcyclopropane
fragment becomes larger (111.0(1)  138.7(1)). Some
bond lengths and bond angles are noticeably changed. For
instance, the C(3)—N(2) and N(2)—C(11) bond lengths
in free ligand 1 are 1.458(2) and 1.386(2) Å (the
C(3)N(2)C(11) angle is 127.4(1)), while the respective
bonds in complex 3 are longer (1.531(2) and 1.462(2) Å)
and the C(3)N(2)C(11) angle is smaller (see Table 3).
In contrast to compound 1, coordinated ligand 2 in
complex 4 retains the original conformation of its sixꢀ
membered carbocycle. Some bond lengths and bond anꢀ
gles are also changed. For instance, the N(2)—C(11) and
N(2)—C(2) bond lengths in free ligand 2 are 1.400(2) and
1.486(2) Å (the C(2)N(2)C(11) angle is 124.2(1)), while
the respective bonds in complex 4 are longer (1.465(3) and
1.546(3) Å) and the C(2)N(2)C(11) angle is smaller (see
Table 4).
the frequencies of both their stretching and bending vibraꢀ
tions are no longer the same as in the free ligands. For
instance, the (N—O) band in the IR spectra of complexꢀ
es 3 and 4 is shifted to the higher frequencies by ~100 and
56 cm–1, respectively. The (NH) band is shifted to the
lower frequencies by ~20 cm–1 for both complexes. The
coordination of the Cl atoms to the Pd atom is evident
from new intense bands appearing at 368—315 cm–1 in
the spectra of complexes 3 and 4. The data from IR
spectroscopy are consistent with Xꢀray diffraction data for
these complexes.
According to NMR data, the solution of complex 3 in
CDCl3 contains only one of its diastereomers in which the
hydrogen atom of the NH group is cis to the neighboring
Me group (in agreement with Xꢀray diffraction data). The
solution of complex 4 in CDCl3 contains two isomers in
a ratio of about 7 : 1. The predominant isomer shows
a transꢀarrangement of the hydrogen atom of the NH group
and the adjacent Me group. This isomer makes up the
solid phase of complex 4 (Xꢀray diffraction and powder
1
diffraction data). Comparative analysis of the H and
13C NMR spectra of ligands 1 and 2 and complexes 3
and 4 (Tables 6, 7) reveals that the molecular structures
of complexes 3 and 4 are retained upon dissolution in
CDCl3. The spectral parameters pertaining to the terpene
moieties of the complex molecules are similar to those
found earlier4—7 for diamagnetic PdII complexes with such
ligands.
Some spectral features of complexes 3 and 4 allow
their spatial structures in solution to be envisioned. For
1
instance, the H NMR spectrum of complex 3 is not enꢀ
tirely characteristic of carane derivatives. The signal for
the H(1) atom is anomalously shifted (H –0.44) from its
usual value (H 0.8—0.9). This upfield shift can be exꢀ
plained by the anisotropy of the magnetic susceptibility of
the aromatic ring under the assumption that the molecuꢀ
lar structure of complex 3 is fully retained upon its dissoꢀ
lution. Specifically, the cisꢀarrangement of the H atom of
the NH group and the adjacent Me group bound to the
chelate ring PdN2C2 ensures such an orientation of the
aromatic ring that the H(1) atom becomes strongly shieldꢀ
ed by the ꢀsystem of the benzene ring, which accounts for
the unusual upfield shift of its signal.
In the crystal structure 3, discrete complex molecules
are linked only by weak Hꢀbonds. Structure 4 shows zigꢀ
zag chains formed by the hydrogen bonds O—H...Cl
(O(1)...Cl(1)´, 3.148(3) Å) along the axis a.
In the IR spectra of compounds 1—4, we identified the
bands due to the vibrations of main functional groups
present in their molecules (Table 5). Since the coordinaꢀ
tion involves the N atoms of the oxime and NH groups,
Table 5. Selected vibrational frequencies (cm–1) in the IR spectra of compounds 1—4
1
3
2
4
Assignment
3454, 3420, 3069
1641 sh, 1604
1520
3454, 3257, 3102
1641 w, 1606
1493
3384, 3290, 3069
1651 w, 1599
1510
3400, 3216, 3077
1664, 1601
1490
(OH), (NH)
(C=N), (C=C)cycle
(NH)
1252
1253
1253
1251
 (=C—O—C)14
as
921, 901
—
1020, 1007
353, 341, 326, 315
956, 935
—
1014, 989
368, 348, 319
(N—O)
(Pd—Cl)
Note: w and sh stand for weak and shoulder, respectively.

Pd complexes with amino oximes of terpenes
Russ.Chem.Bull., Int.Ed., Vol. 62, No. 12, December, 2013
2599
Table 6. 1H and 13C NMR spectra (CDCl3) of ligand 1 and complex 3
Atom or
group
1
3
i
i


i (J/Hz)


i (J/Hz)
H
C
H
C
1
2
16.41
37.64
0.86 ddd (9.8, 8.6, 5.0)
proꢀS: 2.38 dd (15.3, 9.8)
proꢀR: 1.59 dd (15.3, 5.0)
20.77
31.31
–0.44 ddd (8.4, 8.4, 8.4)
proꢀS: 1.92 dd (17.2, 8.4)
proꢀR: 1.28 dd (17.2, 8.4)
3
4
5
54.50
164.29
18.33
74.16
171.55
20.56
—
—
proꢀS: 3.09 d (17.4)
proꢀS: 1.33 dd (15.4, 8.4)
proꢀR: 1.99 dd (17.4, 8.6)
proꢀR: 3.44 dd (15.4, 8.4)
6
7
8
9
10
11
12
13
14
15
16
17
21.60
19.49
14.67
28.04
22.43
135.71
111.96
121.13
117.02
109.43
147.20
55.45
—
1.01 dd (8.6, 8.6)
—
0.86 s
1.04 s
1.46 s
—
6.75—6.82
6.75—6.82
6.67 m
6.75—6.82
—
3.85 s
8.97 w.s (W1/2 = 42 Hz)
4.9 w.s (W1/2 = 110 Hz)
22.21
23.18
13.98
27.49
30.08
130.62
126.89
121.40
129.35
112.28
151.19
56.77
—
0.74 ddd (8.4, 8.4, 8.4)
—
0.91 s
0.83 s
2.03 s
—
8.04 dd (8.0, 1.5)
7.05 ddd (8.0, 7.8, 1.2)
7.30 ddd (8.3, 7.8, 1.5)
6.95 dd (8.3, 1.2)
—
3.90 s
9.79 s
=N—OH
N—H
—
—
6.08 br.s (W1/2 = 6 Hz)
1
Table 7. H and 13C NMR spectra of ligand 2 and complexes 4 and 4´
Atom or
group
2 (CCl4—CDCl3,
4 (CDCl3)
i (J/Hz)
4´ (CDCl3)
2 : 1 v/v)
i
i
i


i (J/Hz)




i (J/Hz)
H
C
H
C
H
C
1
2
3
4
50.56
62.19
162.28
29.86
2.47 dd (5.7, 5.7)
—
—
proꢀR: 2.89 ddd
(18.7, 2.9, 2.9)
proꢀS: 2.68 dd
(19.3, 2.5)
48.74
77.56
167.99
29.99
1.66 dd (5.6, 5.6)
—
—
proꢀR: 2.61 ddd
(19.3, 2.2, 2.2)
proꢀS: 3.21 dd
(19.3, 3.9)
49.71
78.02
168.38
30.23
2.09 dd (5.6, 5.6)
2.57 ddd
(19.3, 2.2, 2.2)
3.04 dd
(19.3, 3.9)
5
37.48
2.02 dddd
37.89
2.02 dddd
36.10
1.75 dddd
(5.7, 5.7, 2.9, 2.5)
(5.6, 5.6, 3.9, 2.2)
—
proꢀR: 1.47 d (11.9)
proꢀS: 2.41 dddd
(11.9, 5.6, 5.6, 2.5)
0.91 s
1.22 s
2.11 s
—
7.73 dd (8.0, 1.5)
6.93 ddd (8.0, 7.8, 1.2)
7.21 ddd (8.3, 7.8, 1.5)
6.74 dd (8.3, 1.2)
—
(5.6, 5.6, 3.9, 2.2)
6
7
38.58
28.51
40.84
29.66
42.65
28.53
proꢀR: 1.77 d (10.6)
proꢀS: 2.31 dddd
(11.9, 5.7, 5.7, 2.9)
0.94 s
1.35 s
1.56 s
—
6.82 m
6.70—6.77
6.70—6.77
6.70—6.77
—
0.60 d (11.7)
1,80 dddd
(11.7, 5.6, 5.6, 2.5)
0.98 s
1.22 s
2.36 s
8
9
22.76
28.00
23.44
27.47
24.96
125.98
131.10
119.68
128.88
110.31
152.17
55.56
—
23.86
27.47
25.00
125.98
129.87
121.14
129.78
111.73
152.05
56.34
10
25.04
11
12
13
14
15
16
17
135.35
117.31
120.54
118.93
109.88
149.71
55.37
8.55 dd (8.0, 1.5)
7.03 ddd (8.0, 7.8, 1.2)
7.28 ddd (8.3, 7.8, 1.5)
6.86 dd (8.3, 1.2)
—
3.85 s
9.85 s
3.82 s
9.23 w.s
3.59 s
9.89 s
=N—H
(W1/2 = 46 Hz)
4.3 w.s
N—H
—
6.77 br.s
5.90 br.s
(W1/2 = 240 Hz)
(W1/2 = 5 Hz)
(W1/2 = 6 Hz)

2600
Russ.Chem.Bull., Int.Ed., Vol. 62, No. 12, December, 2013
Kokina et al.
Vertex 80 FTIR spectrometers in the 4000—100 cm–1 range.
Samples were pressed with KBr and polyethylene into pellets.
Optical rotation was measured on a PolAAr 3005 polarimeter.
The melting points of compounds 1 and 2 were determined on
a Mettler Toledo FP900 Thermosystem instrument in open glass
1
capillaries (heating rate 1 deg s–1). H and 13C NMR spectra
were recorded at 27 C on a Bruker DRXꢀ500 spectrometer
(500.132 (1H) and 125.758 MHz (13C)) for solutions in CDCl3
(C = 10—40 mg mL–1) with the signals of the solvent as the
internal standards (C 76.90, H 7.24). The signals were assigned
using 2D correlation experiments (1H—1H and 13C—1H) for
direct coupling constants (J = 135 Hz).
Ligands 1 and 2 were synthesized in two steps as described
for similar ꢀamino oximes.3 First, (+)ꢀ3ꢀcarene and (–)ꢀꢀpinꢀ
ene were transformed into crystalline dimeric nitroso chlorides
under the action of gaseous nitrosyl chloride in CH2Cl2. Then
these nitroso chlorides were treated with excess oꢀanisidine
in MeOH.
(1R,3S,6R)ꢀ3ꢀ(2ꢀMethoxyphenylamino)caranꢀ4ꢀone
(E)ꢀoxime (1). Yield 75%, yellowish crystals, m.p. 159 C (from
MeCN), []25
+128 (c 0.88, EtOH). IR (KBr), max/cm–1
:
The NMR spectra of complex 4 suggest the presence
of its two diastereomers 4 and 4´ (7 : 1) in solution. These
differ by the configuration of the N atom of the NH group:
the major product shows a transꢀarrangement of the
H atom and the Me group at the chelate ring PdN2C2,
while product 4´ is characterized by the cisꢀarrangement.
The cisꢀarrangement of the H atom and the Me group in
structure 4´ is evident from the anomalous chemical shift
of the signal for the proꢀRꢀH(7) atom: H 0.60 (see
Table 7); the usual H value ranges from 1.4 to 1.6. This
upfield shift, as with complex 3, is due to the shielding
effect of the aromatic ring on the proꢀRꢀH(7) atom lying
above its plane.
589
3454 (O—H), 3420 and 1519 (N—H), 1604 and 734 (Ar),
921 (N—O). Highꢀresolution MS: found m/z 288.1831 [M]+.
C17H24N2O2. Calculated M+ = 288.1832. MS, m/z (Irel (%)):
288 (72), 271 (33), 206 (61), 190 (20), 189 (14), 175 (60), 148 (67),
124 (16), 123 (100), 108 (39), 85 (20), 83 (31), 77 (20), 65 (10),
41 (13).
(1R,2R,5R)ꢀ2ꢀ(2ꢀMethoxyphenylamino)pinanꢀ3ꢀone
(E)ꢀoxime (2). Yield 60%, yellowish crystals, m.p. 134 C (from
MeCN), []26
–19 (c 0.46, EtOH). IR (KBr), max/cm–1
:
589
3420—3300 (O—H and N—H), 1682 (CN), 1509 (N—H), 1599
and 745 (Ar), 935 (N—O). Highꢀresolution MS: found m/z
288.1834 [M]+. C17H24N2O2. Calculated M+ = 288.1832. MS,
m/z (Irel (%)): 288 (31), 176 (9), 123 (100), 108 (23).
Dichloro[(4E,1R,3S,6R)ꢀ4ꢀhydroxyiminoꢀ3ꢀ(2ꢀmethoxyphenꢀ
ylamino)carane]palladium(II) (3). A solution of ligand 1 (0.058 g,
0.2 mmol) in acetone (4 mL) was added to a stirred solution of
PdCl2 (0.035 g, 0.2 mmol) in a mixture of conc. HCl (0.5 mL)
and EtOH (5 mL). The resulting orange solution was kept at
room temperature. As the solvent evaporated, a crystalline preꢀ
cipitate formed gradually. The solvent was allowed to evaporate
to a minimum possible volume (~2—3 mL). The orange precipiꢀ
tate was filtered off by suction, washed two times with EtOH,
To sum up, we extended the group of chiral monoamiꢀ
no oximes derived from monoterpenes and obtained optiꢀ
cally active PdII complexes with the new ligands. Using
Xꢀray diffraction and IR and NMR spectroscopy, we strucꢀ
turally characterized ligands 1 and 2 and complexes 3
and 4 and revealed a considerable difference between the
structures of the free and coordinated ligands. We found
that free chiral ꢀamino oximes 1 and 2 are opposite in
specific rotation sign to their complexes 3 and 4.
and dried in a vacuum desiccator. Yield 0.067 g (71%), []24
589
–26 (c 0.26, CHCl3). Found (%): C, 44.0; H, 5.5; N, 6.0.
C17H24N2O2Cl2Pd. Calculated (%): C, 43.8; H, 5.2; N, 6.0.
Dichloro[(4E,1R,2R,5R)ꢀ3ꢀhydroxyiminoꢀ2ꢀ(2ꢀmethoxyꢀ
phenylamino)pinane]palladium(II) (4). A solution of ligand 2
(0.058 g, 0.2 mmol) in acetone (5 mL) was added to a stirred
solution of PdCl2 (0.035 g, 0.2 mmol) in a mixture of conc. HCl
(0.5 mL) and EtOH (5 mL). The resulting solution was worked
up as described for the synthesis of complex 3. Yield 0.020 g
Experimental
The starting materials included PdCl2 (highꢀpurity grade),
(+)ꢀ3ꢀcarene (>96% purity (GLC), b.p. 170—174 C,
nD20 1.4730, []D20 +16.0) obtained by fractionation of pine turpenꢀ
tine, (–)ꢀꢀpinene (>97% purity (GLC), b.p. 154—156 C,
d420 0.858, nD20 1.466, []20578 –50 3) (Fluka AG), oꢀanisidine
(highꢀpurity grade), and nitrosyl chloride produced at the Pilot
chemical plant of the Novosibirsk Institute of Organic Chemisꢀ
try (Siberian Branch of the Russian Academy of Sciences). The
solvents used included acetone (special purity grade), fracꢀ
tionated EtOH, freshly distilled MeCN, MeOH, CHCl3, and
CH2Cl2, and concentrated HCl (reagent grade). Microanalysis
was performed on Hewlett Packard 185 and Carlo Erba 1106
analyzers. IR spectra were recorded on Scimitar FTS 2000 and
(75%), orange crystalline solid, []24 +148 (c 0.29, CHCl3).
589
Found (%): C, 43.9; H, 5.5; N, 6.0. C17H24N2O2Cl2Pd. Calcuꢀ
lated (%): C, 43.8; H, 5.2; N, 6.0.
Colorless transparent single crystals of ligands 1 and 2 were
grown by slow evaporation of their solutions in acetone—EtOH
(1 : 1 v/v).
Growth of single crystals of 3. A solution of ligand 1 (0.029 g,
0.1 mmol) in acetone—EtOH (1 : 1 v/v, 2 mL) was added to
a stirred solution of PdCl2 (0.017 g, 0.1 mmol) in EtOH (2 mL)

Pd complexes with amino oximes of terpenes
Russ.Chem.Bull., Int.Ed., Vol. 62, No. 12, December, 2013
2601
Table 8. Crystallographic parameters and the data collection and refinement statistics for ligands 1 and 2 and complexes 3 and 4
Parameter
1
2
3
4
Empirical formula
Molecular weight
C17H24N2O2
288.38
C17H24N2O2
288.38
C17H24Cl2N2O2Pd
465.68
C17H24Cl2N2O2Pd
465.68
Crystal system
Space group
Orthorhombic
P212121
7.4023(3)
13.0345(6)
16.4637(7)
—
1588.5(1)
4
1.206
Monoclinic
C2
Orthorhombic
P212121
8.8028(4)
12.1227(6)
17.4742(9)
—
1864.7(2)
4
1.659
Orthorhombic
P212121
8.3942(2)
10.3660(2)
21.0005(5)
—
1827.3(7)
4
1.693
a/Å
b/Å
c/Å
/deg
V/Å
Z
20.342(1)
7.3643(3)
14.0772(7)
128.594(1)
1648.2(1)
4

calc/mg cm–3
1.162
0.076
/mm–1
0.079
1.294
1.320
Crystal dimensions/mm
 scan range/deg
Number of measured reflections
0.35×0.01×0.1
1.99—28.29
13333
0.35×0.35×0.15
1.85—27.50
6076
0.2×0.14×0.15
2.04—28.28
15495
0.22×0.18×0.04
1.94—33.49
41236
Number of unique reflections
2256
2036
4624
7025
Rint
0.0439
0.0263
0.0295
0.0408
Number of reflections with I > 2(I)
1985
1886
4543
6390
Number of parameters refined
GOOF on F2
286
1.122
212
1.147
313
0.899
244
0.654
R factor for I > 2(I)
R1
wR2
0.0346
0.0815
0.0424
0.1284
0.0143
0.0363
0.0238
0.0734
R factor for all Ihkl
R1
wR2
0.0439
0.0863
0.0563
0.1284
0.0149
0.0368
0.0305
0.0822
Residual electron density
(max/min), e Å
0.213/–0.192
0.536/–0.418
0.214/–0.316
0.483/–0.648
–3
acidified with a drop of conc. HCl. The resulting solution was
kept in a loosely closed beaker at ~3 C for 24 h.
878392 (2), 878390 (3), and 878391 (4)) or can be made availꢀ
able from the authors upon request.
Growth of single crystals of 4. A solution of PdCl2 (0.017 g,
0.1 mmol) in EtOH (2 mL) acidified with a drop of conc. HCl
was added to a stirred solution of ligand 2 (0.029 g, 0.1 mmol) in
acetone—EtOH (1 : 1 v/v, 2 mL). The resulting solution was
kept as described above for a week.
We are grateful to A. P. Zubareva and O. S. Koshcheeꢀ
va for performing the elemental analysis.
This work was financially supported by the Russian
Foundation for Basic Research (Project No. 10ꢀ03ꢀ00346).
The orange single crystals of complexes 3 and 4 that formed
were withdrawn from the solutions and immersed in Nujol.
Xꢀray diffraction studies. The unit cell parameters and reꢀ
flection intensities were measured at 150 K (for 2, at 293 K) on
a Bruker X8 Apex CCD automatic diffractometer equipped with
an area detector according to a standard procedure (MoꢀK
radiation,  = 0.71073 Å, graphite monochromator). Crystalloꢀ
graphic parameters and the data collection and refinement staꢀ
tistics for structures 1—4 are summarized in Table 8. The space
groups were chosen by analyzing the extinction in the experiꢀ
mental intensity arrays, with support provided by the calculaꢀ
tions performed.
The structures were solved by the direct methods and refined
anisotropically (for nonꢀhydrogen atoms) by the fullꢀmatrix leastꢀ
squares method on F2 with the SHELXLꢀ97 program package.13
The H atoms at the C atoms were located geometrically and
refined using a riding model. Selected bond lengths and bond
angles are given in Tables 1—4. Comprehensive tables of atomic
coordinates, bond lengths, and bond angles have been deposited
with the Cambridge Structural Database (CCDC 878389 (1),
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