Synthesis and characterization of new palladium complexes based on polydentate chiral Schiff base and amines ligands derived from (+)-2-hydroxypinan-3-one

Article abstract of DOI:10.1016/j.ica.2018.03.015

Seven novel palladium complexes of the type [Pd(HL)Cl₂] and [Pd(L)Cl] containing chiral pinane ligands (HL = 3-[(2-aminoethyl)imino]-pinane-2-ol; 3,3′-(ethylenediimino)bis-pinane-2-ol; cis-3-(2-aminoethylamino)-pinane-2-ol; cis-3,3′(ethylenediamino)bis-pinane-2-ol; trans-3,3′(ethylenediamino)bis-pinane-2-ol; 3-[2-(2-hydroxybenzylamino)ethylamino]-pinane-2-ol; L = 3-[2-(3,5-di-tert-butyl-2-hydroxybenzylidene)aminoethylimino]pinane-2-ol) were synthesized in good yields from the direct reaction of chiral nitrogen ligands with Li₂PdCl₄ in MeOH. These synthesized complexes were characterized by means of elemental analysis, FT-IR, multidimensional and multinuclear NMR spectroscopic methods.

Full text of DOI:10.1016/j.ica.2018.03.015

Accepted Manuscript
Research paper
Synthesis and characterization of new palladium complexes based on polyden-
tate chiral Schiff base and amines ligands derived from (+)-2-hydroxypinan-3-
one
Yana A. Gur'eva, Igor N. Alekseev, Irina A. Dvornikova, Olga A. Zalevskaya,
Aleksandr V. Kuchin
PII:
S0020-1693(17)31152-0
https://doi.org/10.1016/j.ica.2018.03.015
ICA 18160
DOI:
Reference:
Inorganica Chimica Acta
To appear in:
Received Date:
Revised Date:
Accepted Date:
31 July 2017
26 January 2018
9 March 2018
Please cite this article as: Y.A. Gur'eva, I.N. Alekseev, I.A. Dvornikova, O.A. Zalevskaya, A.V. Kuchin, Synthesis
and characterization of new palladium complexes based on polydentate chiral Schiff base and amines ligands derived
from (+)-2-hydroxypinan-3-one, Inorganica Chimica Acta (2018), doi: https://doi.org/10.1016/j.ica.2018.03.015
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Synthesis and characterization of new palladium complexes based on polydentate chiral
Schiff base and amines ligands derived from (+)-2-hydroxypinan-3-one
Yana A. Gur’evaa*, Igor N. Alekseeva, Irina A. Dvornikovaa, Olga A. Zalevskayab, Aleksandr V.
Kuchina
a Institute of Chemistry, Komi Scientific Center, Russian Academy of Sciences (Ural Branch),
48, Pervomaiskaya St., 167000 Russia; e-mail: gurjeva-ja@chemi.komisc.ru
b Syktyvkar State University, 55, Oktyabrsky Ave., Syktyvkar, 167001 Russia
Abstract
Seven novel palladium complexes of the type [Pd(HL)Cl2] and [Pd(L)Cl] containing chiral
pinane ligands (HL= 3-[(2-aminoethyl)imino]-pinane-2-ol; 3,3’-(ethylenediimino)bis-pinane-2-
ol; cis-3-(2-aminoethylamino)-pinane-2-ol; cis-3,3’(ethylenediamino)bis-pinane-2-ol; trans-
3,3’(ethylenediamino)bis-pinane-2-ol;
3-[2-(2-hydroxybenzylamino)ethylamino]-pinane-2-ol;
were
L=3-[2-(3,5-di-tert-butyl-2-hydroxybenzylidene)amino)ethylimino]pinane-2-ol))
synthesized in good yields from the direct reaction of chiral nitrogen ligands with Li2PdCl4 in
MeOH. These synthesized complexes were characterized by means of elemental analysis, FT-IR,
multidimensional and multinuclear NMR spectroscopic methods.
Keywords: Palladium complexes; chiral pinane ligands; diimines; diamines; ligands of salen
type, chelate complexes, NMR
1. Introduction
It is known that derivatives of ethylenediamine are widely used in inorganic and
coordination chemistry as ligands in the synthesis of complexes of various transition metals [1-
5], including palladium and platinum [6-8]. Derivatives of ethylenediamine containing chiral
terpene fragments, are well proven as effective chiral ligands in asymmetric catalysis [9-11]. In
recent time, α-pinene nitrogen derivatives have been used as substrates in the synthesis of
enantiomerically pure compounds [12,13], chiral auxiliaries [14, 15], and ligands for asymmetric
synthesis [16–20]. Platinum and palladium complexes, containing diamines ligands, have been
extensively studied and used in oncological practice [21-25]. Palladium complexes with different
ligands show high antibacterial activity [26-29].
During the last two decades, many palladium complexes were tested practically in all the
areas of classic palladium catalysis [30-38]. Especially impressing achievements are related to
the catalysis by palladium complexes of Heck and cross-coupling reactions [39-42].

The simplicity of synthesis of these complexes draw the attention of chemists annually
synthesized and tested hundreds of complex compounds of platinum and palladium with a
variety of ligands. From these points of view, the development of methods of synthesis and
structure investigation of new chiral palladium complexes is highly promising. Natural bicyclic
monoterpenes, are available as both enantiomers are chiral building blocks as ligands for the
synthesis of new palladium complexes. In this article we would like to report for the first time
synthesis and structural studies of palladium complexes with chiral terpen polydentate ligands
Schiff base derivatives of ethylenediamine and (+)-2-hydroxypinan-3-one.
3. Results and Discussion
Chiral ligands, derivatives of ethylenediamine and (+)-2-hydroxypinan-3-one 1 –
monoimin 2, diimin 3, unsymmetrical diamin 4, symmetrical cis,cis- and trans,trans-diamines
5,6, unsymmetrical diimin 7 and diamin 8 were prepared to the method described earlier [20,43].
As starting compound for the synthesis of these chiral ligands (scheme 1) used (+)-2-
hydroxypinan-3-one 1, which was prepared by oxidation of α-pinene with KMnO4 [44]. In the
first step, monoimine 2 was synthesized in 79% yield by heating a solution of ketole 1 and a 20-
fold excess of ethylenediamine in benzene in the presence of F3BOEt2 and molecular sieves.
C2-symmetrical bis-imine 3 was prepared in 51% yield by the reaction of ketole 1 with a three-
fold excess of ethylenediamine. Next, the reduction imine 2 with LiAlH4 in diethyl ether gave
cis-3-aminopinan-2-ol 4 in 67% yield. Similarly by the reduction diimine 3 with LiAlH4 in
diethyl ether and NaBH(AcO)3 in propan-2-ol cis- 5 and trans-amines 6 were obtained in 76 and
82% yields corresponding.
The reaction of monoimine
2
with salicylaldehyde and 3,5-di-tert-butyl-2-
hydroxybenzaldehyde in MeOH at room temperature gave unsymmetrical dihydroxydiimine in
93-95% yield (after crystallization). The reduction of the C=N bond with NaBH4 in MeOH
afforded unsymmetrical diamine 8 with 75% yield.
The chiral pinane ligands 2-8 were used as obtained in the reaction with Li2PdCl4 in
MeOH to give complexes 9-15 with 65-98% yield, air stable pale yellow powders (scheme 2).

OH
HO
N
OH
NH2
N
iv
OH
N
ii
NH2
NH
2
iii-v
7
i
4
HO
OH
OH
O
NH
NH
HO
OH
NH
NH
(+)-1
8
i
ii
5
HO
HO
OH
OH
NH
N
NH
N
iii
3
6
(i) H2N(CH2)2NH2, PhH, F3BOEt2, molecular sieves 4Å, 80°С; (ii) LiAlH4, Et2O, 20°C; (iii)
Na(OAc)3BH, i-PrOH, 20°C; (iv) aldehyde, MeOH, 20°C; (v) NaBH4, MeOH, 20°C.
Scheme 1. Synthesis of chiral pinane ligands (2-8)

3
2
4
Li2PdCl4
Cl
Li2PdCl4
Li2PdCl4
Cl
Cl
Cl
Cl
Cl
Pd
Pd
Pd
HO
N
OH
OH
OH
N
NH
NH
NH
N
2
2
9
10
11
6
5
Li2PdCl4
Cl
Li2PdCl4
Cl
Cl
OH
Cl
OH
Pd
Pd
NH
HN
NH
HN
OH
12
13
OH
8
7
Li2PdCl4
Li2PdCl4
Cl
OH
Cl
OH
O
Pd
Pd
Cl
NH
HN
N
N
HO
14
15
Scheme 2. Synthesis of palladium complexes (9-15)
13
The structures of the seven new complexes 9-15 were determined using NMR (1H, C),
IR-spectroscopy data and were confirmed by elemental analyses. The assignment of the signals
1
13
in NMR spectra has been performed by the use of 2D (1H, Н) COSY, NOESY, (1H, C),
HSQC, HMBC techniques. NMR data of all complexes, their ligands and numbering of atoms
used for NMR assignment presented in Tables 1-3 below, the arrows show characteristic NOE
interactions.

Tables 1-3. NMR data complexes 9-15 and their ligands
9 – Acetone-d6
10 - CDCl3
Complex*
11* - DMSO-d6
Ligand Complex
Ligand
Complex
Ligand
N
13
13C
1H
13C
1H
13C
1H
13C
1H
1H
13C
1H
C
1
2
3
50.4
76.3
176.9
2.08 m
53.0
76.1
188.4
2.01 m
-
50.5
76.4
176.4
2.08 m
52.5 2.13 dd J=5.5, 6.5 54.1
1.92 dd J=5.6, 5.9
54.9 1.66 dd J=5.4, 5.6
76.0
57.8 4.01 dd J=8.5, 8.7
-
-
-
-
**
**
-
-
71.5
57.5
-
-
-
2.80 m
1.27 ddd J=2.5, 5.6, 13.5
2.45 m J=13.5
1.83 m J=5.6, 5.9
-
2.50-2.55 m
2H
3.0-3.1
m 2H
2.04 m
2.55-2.68
m 4H
2.06 m
-
2.80-2.95 m
4H
2.20 m
2.38 m
4
33.7
36.1
33.7
37.8
37.9
29.8
5
6
38.3
38.5
2.06 m
-
38.1
43.0
38.5
38.4
37.7
**
2.06 m 2H
-
40.4
38.3
40.9
39.1
1.97 m
-
-
1.56 d J=10.5
2.35 m
0.86 s
1.34 s
1.49 s
1.60 d J=10.6
2.24 m
1.58 d J=10.6
2.35 m
0.87 s
1.34 s
1.47 s
1.78 d J=11
2.32 m
0.67 s
1.29 s
2.54 s
1.23 d J=10
2.07 dddd J=2.5, 5.6, 5.9, 10
0.92 s
1.28 d J=9.8
2.05 m
0.88 s
7
28.2
26.9
28.2
26.8
28.1
27.9
8
9
22.9
27.3
22.4
26.2
28.9
0.90 s
1.35 s
2.57 s
22.9
27.4
28.4
22.4
26.2
28.4
24.0
27.9
31.3
23.9
28.3
30.5
1.20 s
1.21 s
1.21 s
1.25 s
10 28.3
4.25 dd J=3.6, 12.5
4.45 ddd
J=5.0, 5.6, 12.5
2.67 m
2.68 m
3.08 m
11 53.3 3.31 t J=5.7 60.8
3.00 tt
52.9
2.65-2.75 m 2H
2.74-2.83 m 2H
2.25 very br 4H
50.0
3.55-3.70
m, 4H
3.94 d J=8.8 2H
4.79 d J= 8.8 2H
51.4
55.2
2.26 m
2.65 m
4.57 s
12 42.6
43.2
41.8
46.4
J=5.4, 5.7
2.97 m
5.76 s
4.81 br 1H
5.00 br 1H
OH
NH
-
-
-
-
-
-
3.07 s
-
-
-
5.44 s
-
-
-
-
-
2.13 br
3H
4.72, 4.90 br NH2
6.09 br NH
* - signal 13C was obtained from spectrum HSQC
** - signal not detected
NOE
Cl
Cl
Cl
Cl
Cl
Cl
Pd
Pd
10
1
Pd
OH
HO
N
OH
OH
NH
NH
2
N
NH
N
2
2
6
3
11 12
8
9
7
4
5
11
9
10

12 - DMSO-d6
Complex
13 - CDCl3
Complex
13C
N
Ligand
1H
Ligand
1H
Fragment-1
Fragment-2
Fragment-1
1H
Fragment-2
1H
13C
55.6
77.6
13C
56.7
76.4
1H
1.7 m
13C
55.8
76.1
1H
1.6 m
-
13C
13C
1
2
1.90 m
54.1 2.00 dd J=5.6, 5.8 54.9 2.01 dd J=5.5, 5.7 55.3
1.79 dd J=5.0, 5.5
-
-
71.8
-
73.5
-
73.5
-
3.16 dd
J=8.6, 8.8
2.28-2.38 m
4H
1.99 m 2H
-
4.05 dd
J=9.6, 10
2.6-2.7
2H
2.0 m
-
3
4
60.7
33.1
63.2
33.1
61.1
28.0
3.35 m
57.3
2.90 m
57.4
4.42 m
65.4
2.97 m
2.02 m
2.75 m
2.0 m
1.33 m J=13
2.54 m J=13
1.91 m
-
2.22 m
2.72 dd J=11, 13
2.10 m
2.82 dd J=11.4
4.25 dd J=6.2, 11.4
2.15 m
38.1
29.2
40.4
5
6
40.3
39.1
40.3
*
40.2
*
40.5
38.4
40.7
39.1
41.1
39.3
-
-
-
1.62 d J=10.2
2.14 m
1.54 d J=10
2.02 m
0.81 s
1.65 d J=11
2.02 m
0.92 s
1.30 d J=10
2.15 m
1.00 s
1.43 d J=11
2.20 m
1.92 d J=11
2.20 m
7
28.2
24.9
24.6
28.2
27.5
28.0
8
9
23.1
27.7
0.91 s
1.26 s
1.38 s
23.8
28.0
24.6
23.5
28.3
26.9
24.1
28.0
31.3
23.7
28.0
31.0
1.01 s
1.33 s
1.42 s
24.5
28.1
29.2
1.08 s
1.30 s
1.25 s
1.19 s
1.24 s
1.22 s
1.34 s
1.28 s
1.29 s
10 24.9
2.81 br m 2H
2.96 br m 2H
2.6 m 2H
3.13 m 2H
5.12 d J=9.6
4.70 s
2.9 m 2H
3.4 m 2H
6.68 br
4.30 s
2.80-2.85 m
4H
3.03 m
3.48 m
6.21 br d J=6.5
1.90 s
2.27 m
4.48 m
6.50 br s
3.74 s
11 48.5
46.1
55.1
49.5
50.1
60.4
OH
NH
-
-
-
-
-
-
-
-
**
**
-
-
-
-
2.02 br 4H
* - signal is under the DMSO ~40 ppm
** - signal not found in CDCl3
Cl
Cl
Cl
OH
Cl
OH
Pd
Pd
NH
HN
NH
HN
OH
12
OH
13

14 – CDCl3
Ligand Complex*
1H
15 – DMSO-d6
Ligand Complex
13C 1H
16
N
17
18
15
OH
O
13C
13C
1H
13C
55.6
77.6
60.5
1H
1.89 dd J=5.5, 5.6
-
Cl
Pd
1
2
3
50.3 2.05 dd J=5.4, 5.8 52.9
2.13 dd J=5.7, 6.0
56.7 1.58 dd J=5.6, 5.7
14
19
H
N
N
76.5
177.3
-
-
76.1
189.7
-
-
75.9
60.6
-
13
3.12 dd J=8.8, 9.2
1.41 dd J=8.5, 14
2.32 ddd J=5.0, 9.6, 14
1.96 m
2.70 m
14
2.47-2.61 m
2H
4
33.7
38.0
2.90 br 2H
33.1
32.4
2.25 m 2H
NOE
Cl
OH
Cl
5
6
38.4
35.0
2.02 m
-
38.2
37.4
2.07 m
-
40.2
39.2
40.2
39.3
1.76 m
-
10
Pd
1
2
-
13
6
9
8
19
3
7
NH
HN
1.49 d J=10.3
2.31 m
0.70 s
1.76 d J=10.8
2.33 m
1.59 d J=10.0
2.14 m
1.30 d J=10
1.90 m
11 12
7
28.1
27.1
24.7
24.1
4
18
17
14
15
5
8
9
22.7
27.4
22.9
26.7
28.6
0.84 s
1.36 s
2.54 s
23.1
27.6
24.8
0.91 s
1.27 s
1.37 s
23.6
28.8
24.7
0.74 s
1.14 s
1.21 s
HO
15
16
1.26 s
1.45 s
10 28.4
3.86-4.06 m
2H
3.58-3.77 m
2H
4.18 dd J=3.0, 12
4.49 ddd J=4.3, 4.7, 12
3.52 ddd J=3.0, 4.7, 13
3.63 dd J=4.7, 13
2.73 m 1H
3.24 m 1H
2.35 m 1H
2.78 m 1H
3.67 d J=12.5
3.87 dd J=4.7, 12.5
-
11 59.7
59.4
58.6
48.4
47.2
52.4
54.2
48.6
48.2
HMBC (14): H10-C3, CH3(t-Bu-16)-C16,
CH3(t-Bu-18)-C18, CH3(t-Bu-16)-C(t-Bu-
16), CH3(t-Bu-18)-C(t-Bu-18).
2.74-3.02 m 4H
4.05 s 2H
12 50.9
13 167.0
8.38 s
159.7
7.50 s
HMBC (15): H19-C13, 15OH-C14, 15OH-
C15, 2OH-C3, H13-C14, H10-C3, H10-C2.
14 117.8
15 158.2
16 140.0
17 126.8
18 136.6
19 125.8
-
-
-
118.7
161.1
140.6
131.0
137.2
126.9
-
-
-
122.5
158.2
116.5
128.7
119.0
128.4
-
-
122.1
156.6
115.6
-
6.86 d J=7.8
7.20 J=7.6, 7.8
6.80 dd J=7.2, 7.6
7.03 J=7.2
6.89 d J=8.1
129.9 7.20 dd J=7.8, 8.1
119.6 6.95 dd J=7.2, 7.8
7.39 d J=2.4
-
7.10 d J=2.4
7.44 d J=1.9
-
6.96 d J=1.9
133.1
8.22 d J=7.2
4.30 s (C2)
9.73 s (C15)
5.11 br d J=10 (C11)
6.56 br (C12)
OH
NH
-
-
2.71 s (C2)
-
-
-
6.19 s (C2)
-
-
-
-
4.20 br 4H
-
* - additional signals for 14
t-Bu-16: 13C - 35.8 (C)+29.5 (3CH3), 1H - 1.45 s (9H); t-Bu-18: 13C - 33.9 (C)+31.3 (3CH3), 1H - 1.28 s (9H) (complex).
t-Bu-16: 13C - 35.0 (C)+29.4 (3CH3), 1H - 1.45 s (9H); t-Bu-18: 13C - 34.1 (C)+31.5 (3CH3), 1H - 1.33 s (9H) (ligand).

In the formation of imine-amine complex 9 compared to the ligand, we observed a downfield
shift the signal C3 by 11 ppm and 7 ppm C11. Additionally, in the spectrum of 1H for amino-ethylene
fragment in the ligand are observed in the expected triplet (2H, H-11) and a triplet of triplets (2H, H-
12) and the broad signal of NH2 protons, and in the complex with the formation of five-membered
cycle is fixed configuration of all six protons amino-ethylene fragment, which leads to differentiation
of all signals protons.
The study of the complex 10 spectra showed the presence of only one set of signals in NMR
spectra, which indicates the symmetry of the molecule. The slightest asymmetry leads to a double set
of signals that we observed in the complexes 12 and 13.
In the spectrum of complex 10 a downfield shift signal C11 at 4 ppm has been observed, but also
1
strong changes in the representation of signals H of the ethylene bridge: multiplet in ligand at 3.55-
3.70 ppm of 4H, and in the complex the doublet of 2H at 3.94 ppm (J=8.8 Hz) and a doublet of 2H at
4.79 ppm (J=8.8 Hz) for the two pairs of nonequivalent geminal protons.
For ethylene-diamine complex 11 there are several other NMR spectra changes in comparison
with the ligand associated with the formation of a new chiral centre on the nitrogen atom – shift of the
C2 signal downfield by 4.5 ppm, the signal of H-3 change the multiplicity of the signals and shifted
downfield by 1.2 ppm. The signal C4 is shifted to the opposite in a strong field by 8 ppm, there have
been changes and the signals of both protons on it. The changes in signals aminoethylene fragment are
similar to those in the complex 9.
Is of interest the formation of chelate complex 15, in which coordination is only for amino
groups, phenolic OH-group is not involved. Described the formation of salen-type complex from the
corresponding ligand, but with ethylene-diimine bridge [45]. We can assume that the complexation
with ethylene-diimine bridges in the presence of OH-group in ortho-position in the aromatic ring is
mainly the salen-type proceeded.
In the structure 14 hydroxyl group of the aromatic ring failed to be detected by spectroscopic
methods, at the same time, there has been a shift signal C15-O in the spectrum 13C downfield by 3 ppm
compared to the ligand, which is typical during the transition from alcohol to ether. Opposite the
compound 15 we do not observe a shift signal C15-O compared with the ligand, but seen far H-C
interaction HO-C15 and HO-C14 in the HMBC NMR spectra.
IR data for terpen ligands and corresponding complexes are given in table 4. Thus, the IR data
of compounds 9-15 demonstrated the presence of the group of bands relating to the vibrations of C=N,
OH, NH, NH2, the appearance of intense bands 345-305 cm-1 relating to the vibrations of Pd-Cl bonds.
In the IR spectra of palladium complexes 9, 10 and 14, containing imines ligands, we observed that
the stretching vibrations of C=N group shift to lower frequencies (from 1658,1664 and 1631 cm-1 in
spectra of imines to 1612, 1645 and 1618 cm-1 in spectra of complexes), that indicates the participation

imino-group in coordination with palladium. The same pattern is observed for the complexes 11, 12,
13 and 15, containing diamines ligands (in the IR spectra of the palladium complexes observed low-
frequency shift of the stretching vibrations of NH and NH2 groups).
Table 4. Selected vibrational wavenumbers (cm-1) in IR spectra of ligands L2-L8 and complexes 9-15
L2
L3
L4
L5
Assignment
9
10
11
12
 (OH-terp)
 (NH2),  (NH)
 (C=N)
3368
3296
1658
1596
3379
3219
1612
1572
3284
-
1664
-
L7
3298
-
1645
-
3504
3443
3292
3439
3167
-
3442, 3423 3395, 3327 3253
-
1471,1369
L8
-
-
1496, 1362 1454
1476
 (NH2),  (NH)
L6
Assignment
 (OH-terp)
 (NH2),  (NH)
 (C=N)
 (NH2),  (NH)
 (OH-phenol)
13
14
15
3350
3296
-
1473
-
3445
3423
-
1469
-
3404
-
1631
-
3304
-
1618
-
-
3313
3311
-
1591
3392
3296
3285
-
1567
3382
3415
IR data of complex 14 demonstrated the disappearance of the band 3415 cm-1 corresponding to
the phenolic hydroxyl group while going from diimin 7 to complex 14 which together with the data of
NMR spectroscopy for this complex confirms the involvement of phenolic hydroxyl groups to
coordinate with palladium and formation of the salen-type complex.
2. Experimental
Materials and methods
All reactions for the synthesis of the complexes (9-15) were done using standard Schlenk type
flasks and were carried out under air atmosphere. The solvents used were of analytical grade. All
reagents and solvents were purchased from Sigma-Aldrich, Merck and Fluka. The NMR experiments
1
were carried out using a Bruker AVANCE-II-300 spectrometer operating at 300.17 MHz for H and
13
1
75.48 MHz for C. H chemical shift data are given in units δ relative TMS calibrated with residual
protonic solvent (CHCl3 at 7.26, DMSO at 2.52 and acetone-d6 at 2.08 ppm). The multiplicity of a
signal is indicated as follows: br, broad; s, singlet; d, doublet; m multiplet; dd, doublet of doublets. 13C
chemical shifts are given relative TMS calibrated to the solvent, CDCl3 at 77.07, DMSO-d6 at 40.04
1
and acetone-d6 at 30.6 ppm. H and 13C chemical shifts were measured and assigned by 2D
1
experiments. 2D inverse proton detected homonuclear H–1H (COSY, NOESY) and heteronuclear
shift correlation spectra, HSQC (1H-13C) and HMBC (1H-13C) were obtained using standard pulse
sequence from the Bruker library. The coupling constants (J) were given in Hz. The FT-IR spectra of
the synthesized novel complexes were recorded in the 200-4000 cm-1 region on FT-IR spectrometer
Shimadzu IR Prestige 21 on thin films or KBr tablets. Optical rotations were obtained with

automatized digital polarimeter Optical Activity PolAAr 3001 (England). Melting points were
determined with Gallencamp-Sanyo apparatus. Elemental analyses were performed by using EA 1110
CHNS-O apparatus.
Synthesis of complex 9
A suspension of PdCl2 (0.2 g; 1.0 mmol) and LiCl (0.1 g; 2.0 mmol) in MeOH (5 mL) was
refluxed for 1 h on a water bath. A dark red solution of Li2PdCl4 was added to a solution of chiral
pinane ligand 2 (1.0 mmol) in methanol (4 mL), the mixture was stirred at room temperature for 5 h.
The solvent was removed under reduced pressure, the residue was dissolved in benzene and purified
by chromatography (SiO2, eluent benzene-acetone, 50 : 1). The solvents were removed under reduced
pressure. The product was washed with diethyl ether (3-8 mL) and dried under vacuum. Yellow
powder was obtained; yield: 66%; m.p.: 215-216 ºC.
Elemental analysis calcd. (%) for C12H22Cl2N2OPd (386.40 g/mol): C 37.2, H 5.7, N 7.2.; found:
C 37.1, H 5.4, N 7.0; [α]D25 +105.3 (с 0.1, acetone).
Synthesis of complex 10
According to the same conditions and procedure for the 9 complex, the 10 complex was prepared
from chiral pinane ligand 3 (0.1 g, 0.3 mmol) and Li2PdCl4 (0.1 g, 0.3 mmol) in MeOH (5 mL) at 24
ºC for 6 h. A yellow powder was obtained; yield: 68 %; m.p.: 120-121 ºC.
Elemental analysis calcd. (%) for C22H36Cl2N2O2Pd (536.40 g/mol): C 49.2, H 6.7, N 5.2; found:
C 48.8, H 6.5, N 4.8; [α]D25 +44.7 (c 0.1, CHCl3).
Synthesis of complex 11
According to the same conditions and procedure for the 9 complex, the 11 complex was prepared
from chiral pinane ligand 4 (0.05 g, 0.2 mmol) and Li2PdCl4 (0.06 g, 0.2 mmol) in MeOH (5 mL) at
24 ºC for 3 h. A yellow powder was obtained; yield: 84 %; m.p.: 182-183 ºC.
Elemental analysis calcd. (%) for C12H24Cl2N2OPd (388.40 g/mol): C 37.1, H 6.2, N 7.2; found:
C 37.3, H 6.5, N 7.0; [α]D25 +85.3 (c 0.1, CHCl3).
Synthesis of complex 12
According to the same conditions and procedure for the 9 complex, the 12 complex was prepared
from chiral pinane ligand 5 (0.05 g, 0.1 mmol) and Li2PdCl4 (0.03 g, 0.1 mmol) in MeOH (5 mL) at
24 ºC for 4 h. A yellow powder was obtained; yield: 98 %; m.p.: 152-153 ºC.
Elemental analysis calcd. (%) for C22H40Cl2N2O2Pd (540.40 g/mol): C 48.9, H 7.4, N 5.2; found:
48.5, H 7.2, N 4.9; [α]D25 -116.0 (c 0.1, CHCl3).

Synthesis of complex 13
According to the same conditions and procedure for the 9 complex, the 13 complex was prepared
from chiral pinane ligand 6 (0.06 g, 0.2 mmol) and Li2PdCl4 (0.05 g, 0.2 mmol) in MeOH (5 mL) at
24 ºC for 6 h. A yellow powder was obtained; yield: 97 %; m.p.: 155-156 ºC.
Elemental analysis calcd. (%) for C22H40Cl2N2O2Pd (540.40 g/mol): C 48.9, H 7.4, N 5.2; found:
48.6, H 7.1, N 5.0; [α]D25 +147.8 (c 0.2, CHCl3).
Synthesis of complex 14
According to the same conditions and procedure for the 9 complex, the 14 complex was prepared
from chiral pinane ligand 7 (0.05 g, 0.1 mmol) and Li2PdCl4 (0.03 g, 0.1 mmol) in MeOH (5 mL) at
24 ºC for 3 h. A red powder was obtained; yield: 70 %; m.p.: 177-178 ºC.
Elemental analysis calcd. (%) for C27H41ClN2O2Pd (566.40 g/mol): C 57.2, H 7.2, N 4.9; found:
56.9, H 6.9, N 4.6; [α]D26 +272.5 (с 0.1, CHCl3).
Synthesis of complex 15
According to the same conditions and procedure for the 9 complex, the 15 complex was prepared
from chiral pinane ligand 8 (0.06 g, 0.2 mmol) and Li2PdCl4 (0.05 g, 0.2 mmol) in MeOH (5 mL) at
24 ºC for 3 h. A yellow powder was obtained; yield: 52 %; m.p.: 175-176 ºC.
Elemental analysis calcd. (%) for C19H30Cl2N2O2Pd (494.40 g/mol): C 46.1, H 6.1, N 5.7; found:
45.8, H 5.9, N 5.4; [α]D25 -27.7 (с 0.1, CHCl3).
4. Conclusion
In summary, seven novel palladium(II) complexes with chiral pinane ligands were obtained by
the direct reaction of Li2PdCl4 with 3-[(2-aminoethyl)imino]-pinane-2-ol, 3,3’-(ethylenediimino)bis-
pinane-2-ol, cis-3-(2-aminoethylamino)-pinane-2-ol, cis-3,3’(ethylenediamino)bis-pinane-2-ol, trans-
3,3’(ethylenediamino)bis-pinane-2-ol, 3-[2-(2-hydroxybenzylamino)ethylamino]-pinane-2-ol, 3-[2-
(3,5-di-tert-butyl-2-hydroxybenzylidene)amino)ethylimino]pinane-2-ol in MeOH in a molar ratio of
1:1 in good yields. On the basis of the FT-IR, NMR spectra and elemental analysis of the ligands and
the corresponding Pd(II) complexes, we concluded that the ligands are bidentately and tridentate
coordinated to the palladium(II) ion.
Acknowledgements: The authors acknowledge the Center for Collective Use (CCU) ‘Khimiya’ of the
Institute of Chemistry of the Komi Science of the Ural Branch of the Russian Academy of Sciences
(RAS). The work was supported by the Russian Foundation for Basic Research and the Government
of the Komi Republic, the project 16-43-110179 r_a.

Appendix A. Supplementary data
Supplementary data associated with this article can be found, in the online version, at
http://dx.doi.org/10.1016/j.ica..... .
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Seven novel palladium complexes containing
were synthesized.
Their structures were characterized by elemental analysis and spectroscopic methods.

OH
HO
N
OH
NH2
N
iv
OH
N
ii
NH2
NH
2
iii-v
7
i
4
HO
OH
OH
O
NH
NH
HO
OH
NH
NH
(+)-1
8
i
ii
5
HO
HO
OH
OH
NH
N
NH
N
iii
3
6
(i) H2N(CH2)2NH2, PhH, F3BOEt2, molecular sieves 4Å, 80°С; (ii) LiAlH4, Et2O, 20°C; (iii)
Na(OAc)3BH, i-PrOH, 20°C; (iv) aldehyde, MeOH, 20°C; (v) NaBH4, MeOH, 20°C.
Scheme 1. Synthesis of chiral pinane ligands (2-8)

3
2
4
Li2PdCl4
Cl
Li2PdCl4
Li2PdCl4
Cl
Cl
Cl
Cl
Cl
Pd
Pd
Pd
HO
N
OH
OH
OH
N
NH
NH
NH
N
2
2
9
10
11
6
5
Li2PdCl4
Cl
Li2PdCl4
Cl
Cl
OH
Cl
OH
Pd
Pd
NH
HN
NH
HN
OH
12
13
OH
8
7
Li2PdCl4
Li2PdCl4
Cl
OH
Cl
OH
O
Pd
Pd
Cl
NH
HN
N
N
HO
14
15
Scheme 2. Synthesis of palladium complexes (9-15)