Synthesis and crystal structures of palladium(II) complexes containing benzyl 8-quinolyl sulfide and phenethyl 8-quinolyl sulfide

Article abstract of DOI:10.1016/S0277-5387(02)00864-1

Four palladium(II) complexes [PdX₂(L-N,S)] (X = Cl, Br; L: BzSq = benzyl 8-quinolyl sulfide, PheneSq = phenethyl 8-quinolyl sulfide) were prepared. The crystal structure of [PdCl₂(BzSq-N,S)] revealed the presence of an intraligand st

Full text of DOI:10.1016/S0277-5387(02)00864-1

Polyhedron 21 (2002) 843ꢁ848
/
www.elsevier.com/locate/poly
Synthesis and crystal structures of palladium(II) complexes
containing benzyl 8-quinolyl sulfide and phenethyl 8-quinolyl sulfide
Masakazu Kita a,*, Shin-ichi Abiko a, Akira Fuyuhiro b, Kazuaki Yamanari b,
Katsuo Murata a, Shinsuke Yamashita a
a Chemistry Department, Naruto University of Education, Takashima, Naruto 772-8502, Japan
b Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan
Received 14 September 2001; accepted 8 January 2002
Abstract
Four palladium(II) complexes [PdX2(L-N,S)] (Xꢀ
/
Cl, Br; L: BzSqꢀ
/
benzyl 8-quinolyl sulfide, PheneSqꢀphenethyl 8-quinolyl
/
sulfide) were prepared. The crystal structure of [PdCl2(BzSq-N,S)] revealed the presence of an intraligand stacking between the
phenyl and quinolyl groups of BzSq. This stacking interaction was confirmed even in Me2SO, MeCN and MeNO2. On the other
hand, [PdCl2(PheneSq-N,S)] did not show such an intraligand stacking both in the solid and in solutions. # 2002 Published by
Elsevier Science Ltd.
Keywords: Palladium(II) complexes; Benzyl 8-quinolyl sulfide; Phenethyl 8-quinolyl; Crystal structures
1. Introduction
interligand stacking interactions for these complexes
both in solid and in several solvents.
Aromatic interactions such as face-to-face pꢁ
/
p, face-
to-edge pꢁp, and CH-p play an important role in
/
molecular recognition [1]. Such interactions have been
found in many coordination compounds. For example,
there is a face-to-face interligand stacking between a
phenyl group of 1,2-bis(diphenylphosphino)ethane
(dppe) and an acetylacetonato (acac) ring in cis-
[Co(CN)2(acac)(dppe)] in the solid [2]. This stacking
2. Experimental
2.1. BzSq
An ethanol solution (30 cm3) containing 1.0 g of 8-
quinolinethiol (5.1 mmol) and 0.64 g of benzyl chloride
(5.1 mmol) was refluxed for 24 h, until the initial yellow
color disappeared. After cooling, white needlelike crys-
tals were obtained by addition of 100 cm3 of water.
Yield: 1.1 g (86%). Found: C, 75.75; H, 5.24; N, 5.51%.
Calc. for C16H13NS: C, 75.85; H, 5.94; N, 5.53%. NMR:
1
mode is confirmed in CHCl3 by its H NMR spectrum.
Similar pꢁ
reported in [Cu(bpy)(
idine and -tyrꢀ -tyrosine) [3], [Pd(bpy)(
3H2O glyꢀ -tyrosylglycine) [4], [Cu(bpy)(
-tyr×
trp)]ClO4 ( -trpꢀ -tryptophan) [5].
Here we report the synthesis of four palladium(II)
complexes [PdX2( -N,S)] (XꢀCl, Br; L: BzSqꢀbenzyl
8-quinolyl sulfide, PheneSqꢀphenethyl 8-quinolyl sul-
/
p stacking phenomena in the solid have been
-tyr)(ClO4-O)] (bpyꢀ2,2?-bipyr-
-tyr×gly)]×
L
/
L
/
L
L
/
/
(
L
/
/
L
L-
L
/L
dH (J (Hz), d6-DMSO) 8.89(dd, J2ꢁ3
1H, H(2)), 8.35(dd, J3ꢁ4 8.3, J2ꢁ4
7.72(d, J5ꢁ6 8.0; 1H, H(5)), 7.63(d, J6ꢁ7
H(7)), 7.58(q, J2ꢁ3 4.1, J3ꢁ4 8.3; 1H, H(3)), 7.52(t,
J5ꢁ6 8.0, J6ꢁ7 7.3; 1H, H(6)), 7.49(d, J12ꢁ13
ꢀ
/
4.1, J2ꢁ4
1.4; 1H, H(4)),
7.3; 1H,
ꢀ
/
1.4;
ꢀ
/
ꢀ
/
L
/
/
ꢀ
/
ꢀ
/
/
ꢀ
/
ꢀ
/
fide) and examine whether there are any intra- and/or
ꢀ
/
ꢀ
/
ꢀ
/
7.9;
8.1;
8.1;
2H, H(12) and H(16)), 7.34(t, J12ꢁ13
2H, H(13) and H(15)), 7.29(t, J13ꢁ14
ꢀ/7.9, J13ꢁ14
ꢀ
/
ꢀ/8.1, J14ꢁ15
ꢀ
/
1H, H(14)), 4.34(s; 2H, H(21)); dC(d6-DMSO)
149.2(C(2)), 144.5(C(10)), 138.2(C(9)), 137.0(C(11)),
136.3(C(4)), 128.8(C(12) and C(16)), 128.4(C(13) and
* Corresponding author. Tel.: ꢂ81-886-87-1311; fax: ꢂ81-886-87-
1090.
E-mail address: kitam@naruto-u.ac.jp (M. Kita).
0277-5387/02/$ - see front matter # 2002 Published by Elsevier Science Ltd.
PII: S 0 2 7 7 - 5 3 8 7 ( 0 2 ) 0 0 8 6 4 - 1

844
M. Kita et al. / Polyhedron 21 (2002) 843ꢁ848
/
(C(15)),
124.0(C(7)), 123.9(C(5)), 121.9(C(3)), 34.3(C(21)).
127.7(C(8)),
127.0(C(14)),
126.6(C(6)),
benzene (5.1 mmol) was added a solution of sodium
hydroxide (0.45 g, 10.2 mmol) in 50 cm3 of water. The
mixture was refluxed for 24 h and 100 cm3 of diethyl
ether was added to it. The diethyl ether extract was
evaporated to remove diethyl ether. The crude oily
2.2. PheneSq
1
To an ethanol solution (30 cm3) containing 1.0 g of 8-
quinolinethiol (5.1 mmol) and 0.71 g of 2-chloroethyl-
residue, which showed a desirable H NMR spectrum,
was used for the preparations without further purifica-
tion. Yield: 1.1 g (82%).
Table 1
Crystallographic data
Complex
[PdCl2(BzSq)]
[PdCl2(PheneSq)]×CH2Cl2
3. Preparation of complexes
Formula
Crystal system
Space group
C16H13NSCl2Pd
triclinic
C18H17NSCl4Pd
triclinic
¯
1 (#2)
¯
P1 (#2)
P/
/
3.1. [PdX2(BzSq)](Xꢀ
/
Cl and Br)
˚
a (A)
15.601(2)
13.316(3)
9.160(2)
70.08(2)
83.19(1)
66.68(1)
4
10.638(1)
11.156(1)
9.999(1)
114.980(7)
107.346(8)
75.454(8)
2
˚
b (A)
˚
c (A)
To a solution of Na2[PdCl4]×
/H2O (0.52 g, 1.7 mmol)
in 50 cm3 of ethanol was added a solution of BzSq (0.43
g, 1.7 mmol) in 50 cm3 of ethanol. After stirring at room
temperature (r.t.), the resulting orange precipitate was
filtered and recrystallized from CH2Cl2. Yield: 0.31 g
(43%). Found: C, 45.08; H, 2.95; N, 3.25%. Calc. for
a (8)
b (8)
g (8)
Z
3
˚
V (A)
1642.7(6)
l.733
15.73
1016.0(2)
1.725
15.43
Dcalc (g cmꢃ3
)
m (Mo Ka) (cmꢃ1
)
[PdCl2(BzSq)]ꢀC16H13Cl2PdNS: C, 44.83; H, 3.06; N,
/
Transmission factor
Crystal color
Crystal habit
Crystal size (mm)
Scan type
0.776ꢁ/1.000
0.85ꢁ
yellowꢁ
prismatic
/1.00
3.27%. Its NMR data is shown in Table 3. The
corresponding dibromo complex was prepared from
K2[PdBr4] in a similar way. Yield: 0.18 g (88%). Found:
pale yellow
prismatic
/
orange
0.20ꢄ0.12ꢄ0.25 0.25ꢄ0.25ꢄ0.40
v ꢁ2u v ꢁ2u
60 60
/
/
C,36.51; H, 2.53; N, 2.47%. Calc. for [PdBr2(BzSq)]ꢀ
C16H13Br2PdNS: C, 37.13; H, 2.53; N, 2.71%. NMR:
dH(J (Hz), d6-DMSO) 9.62(d, J2ꢁ3 5.0; 1H, H(2)),
8.75(d, J3ꢁ4 8.3; 1H, H(4)), 8.32(d, J6ꢁ7 7.5; 1H,
H(7)), 8.27(d, J5ꢁ6 7.7; 1H, H(5)), 7.92(t, J5ꢁ6 7.7,
J6ꢁ7 7.5; 1H, H(6)), 7.74(t, J2ꢁ3 5.0, J3ꢁ4 8.3; 1H,
H(3)), 7.21(t, J12ꢁ13 6.8; 2H, H(12) and H(16)), 7.09ꢁ
6.98 (m; 3H, H(13)ꢀH(15)), 4.76(d, Jꢀ12.9; 1H,
H(21a)), 4.59(d, Jꢀ12.9; 1H, H(21b)); dC(d6-DMSO)
155.8(C(2)), 130.9(C(9)), 130.6(C(12) and C(16)),
/
2u max (8)
Reflections measured 9h, 9k, ꢂl
Number of reflections 7890
measured
ꢃh, 9k, 9l
6205
ꢀ
/
ꢀ
/
ꢀ
/
ꢀ
/
ꢀ
/
Number of reflections 4900
observed
4942
ꢀ
/
ꢀ
/
ꢀ
/
[½Fo½ꢀ6s(½Fo½)
ꢀ
/
/
R
0.032
0.039
1/s2(½Fo½)2
0.041
0.057
1/s2(½Fo½)2
/
/
Rw
W
/
Fig. 1. ORTEP [8] drawings of [PdCl2(BzSq)] and its intraligand stacking.

M. Kita et al. / Polyhedron 21 (2002) 843ꢁ
/
848
845
Table 3
NMR data of [PdCl2(BzSq)] in d6-DMSO
1H NMR
13C NMR
Position
Fig. 2. ORTEP [8] drawings of [PdCl2(PheneSq)] and its interligand
stacking.
Position d (J/Hz)
d
2
9.42(d, J2 ꢁ 3ꢀ5.2; 1H)
8.74(d, J3 ꢁ 4ꢀ8.2; 1H)
8.32(d, J6 ꢁ 7ꢀ7.4; 1H)
8.27(d, J5 ꢁ 6ꢀ8.0; 1H)
7.92(t, J5 ꢁ 6ꢀ8.0, J6 ꢁ 7ꢀ7.4; 1H)
7.74(t, J2 ꢁ 3ꢀ5.2, J3 ꢁ 4ꢀ8.2; 1H)
7.27(t, J12 ꢁ 13ꢀ6.1; 2H)
2
10
153.6
Table 2
˚
4
150.5
1470.7
136.9
133.4
131.6
130.2
130.1
128.6
128.4
127.9
126.1
123.2
47.2
Selected bond distances (A) and bond angles (8) for [PdCl2(BzSq or
PheneSq)]
7
4
5
7
11
[PdCl2(BzSq)]
Bond lengths
6
3
12,16
5
Pd(1)ꢀCl(1)
Pd(1)ꢀCl(2)
Pd(1)ꢀS(1)
Pd(1)ꢀN(1)
S(1)ꢀC(8)
S(1)ꢀC(10)
C(10)ꢀC(11)
2.315
Pd(2)ꢀCl(21)
Pd(2)ꢀCl(22)
Pd(2)ꢀS(2)
Pd(2)ꢀN(2)
S(2)ꢀC(28)
S(2)ꢀC(30)
C(30)ꢀC(31)
2.311(1)
2.283(1)
2.237(1)
2.036(4)
1.752(7)
1.832(5)
1.489(7)
9
2.293(1)
2.248(1)
2.046(3)
1.780(4)
1.848(5)
1.489(7)
13,14,15 7.08ꢁ
21a
21b
/
7.00(m; 3H)
4.69(d, Jꢀ12.9; 1H)
4.51(d, Jꢀ12.9; 1H)
12,16
6
14
13,15
8
3
21
Bond angles
Cl(1)ꢀPd(1)ꢀCl(2)
Cl(1)ꢀPd(1)ꢀS(1)
Cl(1)ꢀPd(1)ꢀN(1)
Cl(2)ꢀPd(1)ꢀS(1)
Cl(2)ꢀPd(1)ꢀN(1)
S(1)ꢀPd(1)ꢀN(1)
Pd(1)ꢀS(1)ꢀC(8)
Pd(1)ꢀS(1)ꢀC(10)
C(8)ꢀS(1)ꢀC(10)
S(1)ꢀC(10)ꢀC(11)
91.07(4) Cl(21)ꢀPd(2)ꢀCl(22)
177.45(5) Cl(21)ꢀPd(2)ꢀS(2)
95.65(9) Cl(21)ꢀPd(2)ꢀN(2)
87.18(4) Cl(22)ꢀPd(2)ꢀS(2)
172.74(9) Cl(22)ꢀPd(2)ꢀN(2)
86.01(9) S(2)ꢀPd(2)ꢀN(2)
91.28(5)
177.63(5)
95.6(1)
129.3(C(6)), 129.0(C(14)), 128.5(C(13) and C(15)),
127.9(C(8)), 124.1(C(3)), 48.3(C(21)).
86.69(5)
173.1(1)
86.5(1)
3.2. [PdX2(PheneSq)](Xꢀ/Cl and Br)
99.1(1)
104.5(2)
100.3(2)
115.3(3)
Pd(2)ꢀS(2)ꢀC(28)
Pd(2)ꢀS(2)ꢀC(30)
C(28)ꢀS(2)ꢀC(30)
S(2)ꢀC(30)ꢀC(31)
99.0(2)
107.9(2)
101.6(2)
115.3(3)
To a solution of Na2[PdCl4]×
/
H2O (0.24 g, 0.8 mmol)
in 50 cm3 of ethanol was added a solution of PheneSq
(0.21 g, 0.8 mmol) in 50 cm3 of ethanol. After stirring at
r.t., the resulting orange precipitate was filtered and
recrystallized from CH2Cl2. Yield: 0.30 g (85%). Found:
C, 40.88; H, 3.19; N, 2.70%. Calc. for [PdCl2-
[PdCl2(pheneSq)]
Bond lengths
Pd(1)ꢀCl(1)
Pd(1)ꢀCl(2)
Pd(1)ꢀS(1)
Pd(1)ꢀN(1)
S(1)ꢀC(8)
S(1)ꢀC(10)
C(10)ꢀC(20)
C(20)ꢀC(11)
2.315(1)
2.287(1)
2.2530(9)
2.036(3)
1.775(4)
1.828(4)
1.507(6)
1.519(2)
(PheneSq)]ꢀC17H15Cl2PdNS: C, 40.97; H, 3.25; N,
/
2.65%. Its NMR data is shown in Table 4. The
corresponding dibromo complex was prepared from
K2[PdBr4] in a similar way. Yield: 0.38 g (88%). Found:
C,36.92; H, 2.77; N, 2.38%. Calc. for [PdBr2-
Bond angles
(PheneSq)]ꢀ
2.64%. NMR: dH(J (Hz), d6-DMSO) 10.14 (d, J2ꢁ3
5.3; 1H, H(2)), 8.48 (d, J3ꢁ4 8.2; 1H, H(4)), 8.04(d,
7.2; 2H, H(7) and H(5)), 7.76(t,
7.2; 1H, H(6)), 7.67(q, J2ꢁ3 5.3,
3.9; 5H, H(12)ꢀ
11.9; 1H, H(22)), 3.58(s; 2H,
11.9; 1H, H(21b)); dC(d6-DMSO)
150.4(C(10)),140.4(C(4)), 137.5(C(7)),
135.7(C(11)), 131.7(C(5)), 130.2(C(8)), 129.2(C(6)),
/
C17H15Br2PdNS: C, 38.41; H, 2.84; N,
Cl(1)ꢀPd(1)ꢀCl(2)
Cl(1)ꢀPd(1)ꢀS(1)
Cl(1)ꢀPd(1)ꢀN(1)
Cl(2)ꢀPd(1)ꢀS(1)
Cl(2)ꢀPd(1)ꢀN(1)
S(1)ꢀPd(1)ꢀN(1)
Pd(1)ꢀS(1)ꢀC(8)
Pd(1)ꢀS(1)ꢀC(10)
C(8)ꢀS(1)ꢀC(10)
S(1)ꢀC(10)ꢀC(20)
C(10)ꢀC(20)ꢀC(11)
91.60(4)
174.96(4)
94.52(8)
87.96(4)
172.42(8)
86.33(8)
98.9(1)
ꢀ
/
ꢀ
/
J5ꢁ6
J5ꢁ6
J3ꢁ4
ꢀ
/
7.5, J6ꢁ7
ꢀ
/
ꢀ
/
7.2, J6ꢁ7
8.2; 1H, H(3)), 7.07(d, Jꢀ
ꢀ
/
ꢀ
/
ꢀ
/
/
/
H(16)), 3.83(d, Jꢀ
H(22)), 3.01(d, Jꢀ
156.9(C(2)),
/
106.7(1)
102.4(2)
113.5(2)
111.4(3)
/

846
M. Kita et al. / Polyhedron 21 (2002) 843ꢁ848
/
129.1(C(12) and C(16)), 128.8(C(13) and C(15)),
127.3(C(14)), 124.2(C(3)), 45.4(C(21)), 36.5(C(22)).
by full-matrix least-square techniques with anisotropic
thermal parameters for non-hydrogen atoms. Hydrogen
atoms were located at positions determined by Fourier-
difference syntheses or by calculations. All calculations
were carried out with the TEXAN [7] software.
4. Crystallography
Single crystals of [PdCl2(BzSq)] (0.25ꢄ
/
0.20ꢄ
/
0.12
0.25 mm)
5. Measurement
mm) and [PdCl2(PheneSq)] (0.40ꢄ0.25ꢄ
/
/
were fixed on the end of a glass fiber with epoxy resin.
They were mounted on a Rigaku AFC-7R diffract-
ometer and the diffraction data were collected at 298 K
UVꢁVis absorption spectra were recorded on an
/
Hitachi U-3400 spectrophotometer, H and 13C NMR
spectra with a Bruker ARX300 spectrometer. X-Ray
crystal analysis was made at the X-ray Diffraction
Service of the Department of Chemistry of Osaka
University.
1
with graphite-monochromated Mo Ka radiation (lꢀ
/
˚
0.71069 A) using v ꢁ2u scan mode. Cell dimensions
/
were determined by least-squares refinement of the
angular positions of 25 independent reflections in the
range 28B
/
2u B398 for each sample. Crystallographic
/
data and experimental details are listed in Table 1. The
position of the palladium was determined by direct
methods (SHELXS-86 [6]) for each complex and the
remaining non-hydrogen atoms were located by subse-
quent Fourier syntheses. The structure was refined on F
6. Results and discussion
Neutral complexes [PdX2(L)] (Xꢀ
/
Clꢃ or Br-; Lꢀ
BzSq or PheneSq) were obtained in high yields by the
/
Fig. 3. Proton NMR spectra of [PdCl2(BzSq)] in several solvents. D is the magnitude of the splitting of phenyl protons and o is the dielectric constant
of solvent.

M. Kita et al. / Polyhedron 21 (2002) 843ꢁ
/
848
847
109.58, which is reasonably ascribed to the intraligand
stacking interaction of BzSq. The dihedral angle C(8)ꢀ
SꢀC(10)ꢀC(11) is 43.9(4)8. The distance between C(11)
and C(9) is 3.60(1) A, which is the standard value for a
pꢁp distance. This stacking conformation generates the
repulsive interactions of PdꢀCl(2)Á Á ÁHꢀC(10) 3.41(2) A
and Pd C(12) 2.99(2) A [11]. Interligand stacking
Table 4
NMR data of [PdCl2(pheneSq)] in DMSO
/
/
/
/
/
/
/
/
/
Á Á ÁHꢀ
/
/
interactions between a phenyl group and another ligand
(for example, bpy) in a given complex have been often
reported [2ꢁ5] but intraligand stacking in the same
/
ligand described here seems to be quite rare. There is no
intermolecular stacking interaction between aromatic
rings in the present complex.
On the other hand, [PdCl2(PheneSq-N,S)] does not
show such an intraligand stacking mode (Fig. 2(a)
(left)). In general, a long alkyl chain is apt to adopt an
anti conformation, that is, trans conformation, due to
the repulsion between adjacent methylene protons. The
1H NMR
13C NMR
Position
Position d (J/Hz)
d
2
9.90(d, J2 ꢁ 3ꢀ5.3, J2 ꢁ 4ꢀ1.5; 1H)
8.48(d, J3 ꢁ 4ꢀ8.3, J2 ꢁ 4ꢀ1.5; 1H)
8.03(d, J3 ꢁ 6ꢀ7.8, J6 ꢁ 7ꢀ7.8; 2H)
7.78(t, J5 ꢁ 6ꢀ7.8, J6 ꢁ 7ꢀ7.8; 1H)
7.68(q, J2 ꢁ 3ꢀ5.3, J3 ꢁ 4ꢀ8.3; 1H)
2
155.3
150.4
140.6
137.5
135.5
131.7
131.3
129.2
129.1
128.9
128.8
127.4
124.0
45.1
4
10
4
7,5
6
7
C(8)-S-C(10)ꢀ
SꢀC(10)ꢀC(20)ꢀ
CH2ꢀC sequence takes an anti conformation, so that
/
C(11) dihedral angle is 56.3(4)8 and the
3
11
5
/
/
/
C(11) one is 173.4(3)8. The SꢀCH2ꢀ
/
/
12,13
14
15,16
7.11ꢁ
3.77ꢁ
3.11ꢁ
/
7.03(m; 5H)
3.46(m; 3H)
3.02(m; 1H)
/
/
9
/
6
the phenyl group becomes apart from the quinolyl. This
is the reason why the PheneSq complex does not have an
intraligand stacking mode. Instead there is an inter-
molecular stacking interaction between two quinolyl
groups of adjacent molecules as shown in Fig. 2(b)
(right). The distance between the quinolyl planes 3.40(1)
12,16
8
13,15
14
3
21
22
˚
36.3
A is considerably shorter than the standard value (3.60
˚
A) for a pꢁ
/
p distance. Since the crystallographic
inversion is located at the center of the intermolecular
quinolyl stacking, the angle between two quinolyl planes
becomes 08.
reaction of [PdX4]2ꢃ with sulfide ligands. They were
characterized by NMR spectroscopy and elemental
analysis.
1
The assignments of H and 13C NMR signals were
carried out by proton homo-decoupling, 1H-detected
multiple quantum coherence (HMQC), and 1H-detected
multiple bondquantum coherence (HMBC) spectra. The
results are listed in Tables 3 and 4.
X-ray crystal structures were determined for
[PdCl2(BzSq)] and [PdCl2(PheneSq)]. ORTEP [8] draw-
ings of the present complexes are shown in Figs. 1 and 2.
Selected bond distances and angles are listed in Table 2.
Though there are two similar but independent molecules
in [PdCl2(BzSq)], we describe only the structure of Pd(1)
hereafter.
1
In the H NMR spectrum of [PdCl2(BzSq-N,S)] an
interesting splitting was observed: the phenyl proton
signals are split into two groups, the group of H(12) and
H(16) (d 7.21) and one of H(13), H(14) and H(15) (d
The BzSq ligand coordinates bidentately through the
Cl bond distance trans to the
N,S donors. The Pdꢀ
/
7.09ꢁ6.98), in d6-Me2SO as shown in Fig. 3. The free
/
˚
sulfur in [PdCl2(BzSq-N,S)] is 2.315(1) A, which is
BzSq in d6-Me2SO shows the phenyl protons at d7.49
(H(12) and H(16)), d 7.34 (H(13) and H(15)), and d 7.29
(H(14)). The changes of chemical shifts on complexation
can be related to the ring current effect [10] of p-
electrons of the quinolyl group by the aromatic intrali-
gand interaction in d6-Me2SO. Similar changes were
observed in CD3OD (7.02 and 6.84) (Fig. 3). On the
other hand, the signals of H(13), H(14), H(15) appear at
relatively low magnetic field and the chemical shift
separations are negligible in CD2Cl2 (d 7.2) or CDCl3 (d
7.2) with low dielectric constants. This result suggests
that the aromatic intraligand interaction is recognized in
high dielectric solvents and does not occur in low
dielectric solvents.
˚
longer by 0.022(1) A than the Pdꢀ
/
Cl one trans to imine.
˚
Cl bond [0.028(1) A]
A similar lengthening of the Pdꢀ
was also observed in [PdCl2(PheneSq-N,S)]. This bond
weakening is known as trans influence [9]. The ligand
/
bite angles [BzSqꢀ
/
86.01(9)8 and PheneSqꢀ86.33(8)8]
/
are normal and typical values. A remarkable feature is
the presence of an intraligand stacking interaction
between the phenyl group and the quinolyl of BzSq
(see Fig. 1(a) (left)). The angle between the phenyl plane
and the quinolyl is 46.68. The top view indicates clearly
the superimposition between the phenyl group and the
quinolyl (Fig. 1(b) (right)). The C(8)ꢀ
100.3(2)8 is considerably less than a tetrahedral angle of
/
Sꢀ
/
C(10) angle of

848
M. Kita et al. / Polyhedron 21 (2002) 843ꢁ848
/
Fig. 4. Proton NMR spectra of [PdCl2(PheneSq)] in several solvents. D is the magnitude of the splitting of phenyl protons and o is the dielectric
constant of solvent.
1
Similar H NMR measurements were carried out for
[PdCl2(pheneSq-N,S)]. However, this complex did not
show any splitting of the phenyl proton signals as shown
in Fig. 4. Thus, the aromatic intraligand interaction
could not be observed in the crystal and in solvents.
Each dibromo complex [PdBr2(BzSq)] or [PdBr2(Phe-
neSq)] showed the same results as the corresponding
dichloro complex. Hence we conclude that
[PdBr2(BzSq)] also has a similar noble intraligand
stacking interaction as [PdCl2(BzSq)] does in solid and
in solvents with high dielectric constants.
References
[1] (a) C.A. Hunter, Chem. Soc. Rev. (1994), 101, and references
therein.;
(b) M. Mishio, M. Hirota, Y. Umezawa, The CHꢁ
/
p Interaction,
Wiley-VCH, 1998;
(c) A. Magistrato, M. Merlin, O.S. Pregosin, U. Rothlisberger,
Organometallics 19 (2000) 3591.
[2] M. Kita, K. Kashiwabara, J. Fujita, Bull. Chem. Soc. Jpn. 61
(1988) 3187.
[3] H. Masuda, T. Sugimori, A. Odani, O. Yamauchi, Inorg. Chim.
Acta 180 (1991) 73.
[4] T. Sugimori, K. Shibakawa, H. Masuda, A. Odani, O. Yamauchi,
Inorg. Chem. 32 (1993) 4951.
[5] O. Yamauchi, A. Odani, H. Masuda, Inorg. Chim. Acta 198ꢁ
(1992) 749.
[6] G.M. Sheldrick, SHELXS-86, Program for Crystal Structure
/
200
7. Supplementary material
Determination, University of Gottingen, 1986.
¨
[7] TEXSAN, Crystal Structure Analysis Package, Molecular Structure
Corporation, 1985 and 1992.
Crystallographic data have been deposited with the
CCDC, 12 Union Road, Cambridge, CB2 1EZ, UK
[8] C.K. Johnson, ORTEP-II. Report ORNL-5138, Oak Ridge National
Laboratory, Oak Ridge, TN, 1976.
(fax: ꢂ44-1223-366033; e-mail: deposit@ccdc.cam.ac.uk
/
[9] M. Kita, K. Kashiwabara, Polyhedron 16 (1997) 2771.
[10] A. Odani, S. Deguchi, O. Yamauchi, Inorg. Chem. 25 (1986) 62.
or www: http://www.ccdc.cam.ac.uk) and are available
on request quoting the deposition numbers 169087 for
[PdCl2(BzSq)] and 169088 for [PdCl2(pheneSq)].
˚
A are absent in
[11] Such repulsive interactions within 3.60
[PdCl2(pheneSq)].