Synthesis and single crystal structures of first examples of tridentate ligands of (Te, N, S) type and their complexes with palladium(II), platinum(II) and ruthenium(II)

Article abstract of DOI:10.1016/j.ica.2007.09.012

The First examples of (Te, N, S) type ligands, 2-CH₃SC₆H₄CH{double bond, long}NCH₂CH₂TeC₆H₄ -4-OCH₃ (L¹) and 2- CH₃SC₆H₄CHNHCH₂ CH₂TeC₆H₄-4-OCH₃ (L²), and their metal complexes, [PdCl(L¹)]PF₆ · CHCl₃ · 0.5H₂O (4), [PtCl(L¹)]PF₆ (5), [PdCl(L²)]ClO₄.CHCl₃ (6), [PtCl(L²)]ClO₄ (7), and [Ru(p-cymene)(L²)](PF₆)₂ · CHCl₃ (8), have been synthesized and characterized. The single crystal structures of 4, 6 and 8 have revealed that both the ligands coordinate in them in a tridentate (Te, N, S) mode. The geometry around Pd in both the complexes has been found to be square planar, whereas for Ru in a half sandwich complex 8, it is found to be octahedral. Between two molecules of 4 there are intra and inter molecular weak Te?Cl [3.334(3) and 3.500(3) A?, respectively] interactions along with weak intermolecular Pd?Te [3.621(2) A?] interactions. The Pd-Te bond lengths are between 2.517(6) and 2.541(25) A? and the Ru-Te bond length is 2.630(6) A?. The crystal structure of [PdCl₂(4-MeO-C₆H₄- TeCH₂CH₂NH₂)] (9) is also determined. It is formed when KPF₆ is not added in the synthesis of 4 and Pd-complex of L¹ is recrystallized. Apart from Te?Cl secondary interactions, C-H?π interactions also exist in the crystal of 9.

Full text of DOI:10.1016/j.ica.2007.09.012

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Inorganica Chimica Acta 361 (2008) 1426–1436
www.elsevier.com/locate/ica
Synthesis and single crystal structures of first examples
of tridentate ligands of (Te, N, S) type and their complexes
with palladium(II), platinum(II) and ruthenium(II)
*
P. Raghavendra Kumar, Shailesh Upreti, Ajai K. Singh
Department of Chemistry, Indian Institute of Technology, New Delhi 110 016, India
Received 6 June 2007; received in revised form 31 August 2007; accepted 11 September 2007
Available online 15 September 2007
Abstract
The First examples of (Te, N, S) type ligands, 2-CH3SC6H4CH@NCH2CH2TeC6H4-4-OCH3 (L1) and 2- CH3SC6H4-
CHNHCH2CH2TeC6H4-4-OCH3 (L2), and their metal complexes, [PdCl(L1)]PF6 Æ CHCl3 Æ 0.5H2O (4), [PtCl(L1)]PF6 (5),
[PdCl(L2)]ClO4.CHCl3 (6), [PtCl(L2)]ClO4 (7), and [Ru(p-cymene)(L2)](PF6)2 Æ CHCl3 (8), have been synthesized and characterized.
The single crystal structures of 4, 6 and 8 have revealed that both the ligands coordinate in them in a tridentate (Te, N, S) mode.
The geometry around Pd in both the complexes has been found to be square planar, whereas for Ru in a half sandwich complex 8, it
˚
is found to be octahedral. Between two molecules of 4 there are intra and inter molecular weak Teꢀ ꢀ ꢀCl [3.334(3) and 3.500(3) A, respec-
˚
tively] interactions along with weak intermolecular Pdꢀ ꢀ ꢀTe [3.621(2) A] interactions. The Pd–Te bond lengths are between 2.517(6) and
˚
˚
2.541(25) A and the Ru–Te bond length is 2.630(6) A. The crystal structure of [PdCl2(4-MeO–C6H4– TeCH2CH2NH2)] (9) is also deter-
mined. It is formed when KPF6 is not added in the synthesis of 4 and Pd-complex of L1 is recrystallized. Apart from Teꢀ ꢀ ꢀCl secondary
interactions, C–Hꢀ ꢀ ꢀp interactions also exist in the crystal of 9.
ꢀ 2007 Elsevier B.V. All rights reserved.
Keywords: Tellurated Schiff bases; (Te, N, S) ligands; Platinum; Palladium; Ruthenium; Metal complex; Synthesis; Single crystal structure; X-ray
diffraction
1. Introduction
propyl) telluride [13,14], bis[(8-(dimethylamino)-1-naph-
thyl] ditelluride [15], bis{(2-[(dimethylamino)methyl]-
phenyl} telluride [16], macrocyclic Schiff bases [17]
bis{2-(N-morpholino)ethyl}telluride [18] and tritelluroe-
thers [19], are the important hybrid organotellurium ligands
belonging to this category. Tellurated Schiff bases which
also belong to this category are scantly known [20,21]. Schiff
bases like ‘Salen’ and related derivatives form complexes
with transition metals which are suitable catalysts for epox-
idation reactions [22–26] and a variety of others like
dehydrogenation plus intramolecular Diels–Alder cycload-
dition [27], enantioselective conjugate addition [28], and
ring opening polymerization [29]. The catalytic properties
of such complexes may favourably change if Te is intro-
duced into ligand skeleton. The lability of M–Te bond
and steric influence of large size Te can, respectively, make
Hybrid organotellurium ligands, which have tri or higher
dentate character, are not known in large number [1–8]. 1,6-
Bis-2-butyltellurophenyl-2,5-diazahexa-1,5-diene [9] bis[(2-
arytelluro)ethyl]amine/methylamine [10], bis(2-aminoethyl)
ditelluride, bis(2-dimethylaminoethyl) ditelluride, bis(2-
aryltelluroethyl) ether, 1,2-bis(2-aryltelluroethoxy) ethane,
N,N,N0,N0-tetrakis(2-aryltelluroethyl) ethane-1,2-diamine,
(where aryl = 4-MeO–C6H4) [11], 2-(2-pyridoethyltelluro)-
ethylpyridine [12], bis(1-methylthiopropyl/ethyl)/(1-amino-
*
Corresponding author. Tel.: +91 011 26591379; fax: +91 011
26581102.
E-mail addresses: ajai57@hotmail.com, aksingh@chemistry.iitd.ac.in
(A.K. Singh).
0020-1693/$ - see front matter ꢀ 2007 Elsevier B.V. All rights reserved.
doi:10.1016/j.ica.2007.09.012

P. Raghavendra Kumar et al. / Inorganica Chimica Acta 361 (2008) 1426–1436
1427
the metal centre easily accessible to substrate and catalytic
reaction more selective. It was therefore thought worth-
while to design ligands L1 and L2, which are of (Te, N, S)
type and understand their ligation with
and SHELXTL for space group, structure determination and
refinements [33,34]. All non-hydrogen atoms were located
from difference Fourier map using geometrical constraints
and were refined anisotropically. The least-squares refine-
3
3
11
9
1
11
9
10
1
10
Te
12
Te
12
8
7
8
7
N
N
4
2
4
2
H
15
15
O
S
13
5
O
S
13
5
6
14
6
14
CH3
CH3
CH3
CH3
L2
L1
Pd(II), Pt(II) and Ru(II) first so that further investiga-
ment cycles on F2 were performed until the model con-
verged. Selected bond lengths and angles are given in
Table 2. The structure of 8 can be solved efficiently in space
groups I2/b and I2/a.
tion on catalytic activities of metal complexes of such
ligands may be carried out. The results of these investiga-
tions are reported in this paper. L1 and L2 both have been
found to coordinate in (Te, N, S) mode with Pd(II) and
Ru(II) as shown by single crystal structures of their
complexes.
The precursors of L2 viz. 1, 2 and 3 (See Scheme 1) were
synthesized by the following methods:
2.4. Synthesis of 1
2. Experimental
2-Ethanolamine (0.48 ml, 8 mmol) dissolved in 10 ml of
dry ethanol was added to 2-methylthiobenzaldehyde (1 ml,
8 mmol) dissolved in 10 ml of dry ethanol along with 0.5 g
2.1. Physical measurement
˚
of 4 A molecular sieves. The mixture was stirred under
The C and H analyses were carried out with a Perkin–
reflux for 4 h and then cooled to room temperature. The
molecular sieves were separated by filtration and the sol-
vent was evaporated on a rotary evaporator, which
Elmer elemental analyzer 240 ꢁC. Tellurium was estimated
by atomic absorption spectrometry. The H and 13C{1H}
1
NMR spectra were recorded on a Bruker Spectrospin
DPX-300 NMR spectrometer at 300.13 and 75 MHz,
respectively. IR spectra in the range 4000–250 cmꢁ1 were
resulted in
K
1
as yellow viscous oil. Yield 90%;
1
M = 3.0 cm2 molꢁ1 ohmꢁ1. NMR: H (CDCl3, 25 ꢁC): d
(vs TMS): 2.29 (bs, 1H, OH), 2.46 (s, 3H, SCH3), 3.79 (t,
J = 5.1 Hz, 2H, H2), 3.91 (t, J = 4.8 Hz, 2H, H1), 7.18–
7.37 (m, 1H, H8), 7.30–7.40 (m, 2H, H7,9 ), 7.79–7.82 (d,
J = 7.66 Hz, 1H, H6), 8.76 (s, 1H, H3); 13C{1H} (CDCl3,
25 ꢁC): d (vs TMS): 16.04 (SCH3), 61.27 (C2), 62.96 (C1),
124.71 (C8 ), 125.84 (C9 ), 126.92 (C6), 127.77 (C7),133.18
(C4), 138.72 (C5), 160.46 (C3). IR (KBr, cmꢁ1): 3556 (O–
H), 1590 (C@N), 705 (C–S).
´
recorded on a Nicolet Protege 460 FT-IR spectrometer as
KBr pellets. The melting points determined in open capil-
lary are reported as such. The conductivity measurements
were carried out in CH3CN (Concentration ca 1 mM) using
ORION conductivity meter model 162.
2.2. Chemicals
2-(4-Methoxyphenyltelluro)ethylamine [30] and bis(4-
methoxyphenyl) ditelluride [31] were synthesized by
reported methods. 2-Ethanolamine and 2-methylthiobenz-
aldehyde were procured from Merck (India) and Aldrich
(USA), respectively, and used as received. The [Ru(p-cym-
ene)2Cl2]2 was prepared by the method reported in litera-
ture the [32].
2.5. Synthesis of 2
1 (0.20 g, ꢂ1 mmol) was dissolved in 20 ml of dry ethanol
and the solution was cooled in an ice bath. Solid NaBH4
(0.38 g, 10 mmol) was added to this cooled reaction mixture
slowly with stirring in a period of 15 min. The contents were
refluxed for 4 h, cooled and the solvent was evaporated
completely on a rotary evaporator. The residue was
extracted with 100 ml of dry dichloromethane and the solu-
tion was filtered and dried with anhydrous sodium sulfate.
The solvent was again removed on a rotary evaporator
completely. Compound 2 was obtained as a highly viscous
2.3. X-ray diffraction analysis
Single crystal X-ray diffraction studies were carried out
on a Bruker SMART CCD diffractometer with MoKa
(0.71073 A) radiations at 25 ꢁC. Table 1 lists the crystal
colorless oil. Yield, 80%; KM = 4.5 cm2 molꢁ1 ohmꢁ1
.
˚
1
data and structural refinement parameters for 4, 6, 8 and
9. The software SADABS was used for absorption corrections
NMR: H (CDCl3, 25 ꢁC): d (vs TMS): 2.38 (bs, 2H, OH
& NH), 2.47 (s, 3H, SCH3), 2.79 (t, J = 4.43 Hz, 2H, H1),

1428
P. Raghavendra Kumar et al. / Inorganica Chimica Acta 361 (2008) 1426–1436
Table 1
Crystal data and refinement parameters of 4, 6, 8 and 9
Empirical formula
C36H40Cl8F12N2O32Pd2S2Te2
C
18H22Cl5NO5PdSTe
C28H36Cl3F12NOP2 Ru STe C9H13ONCl2PdTe
(4)
(6)
(8)
(9)
Formula weight
Temperature (K)
Wavelength (A)
Crystal system
Space group
1654.42
298.0(2)
0.71073
orthorhombic
Pbcm
775.68
298(2)
0.71069
1059.60
298(2)
0.71069
monoclinic
I2/a or I2/b
456.113
273(2)
0.71073
monoclinic
C2/c
˚
triclinic
ꢀ
P1
Unit cell dimensions
˚
a (A)
18.258(3)
14.5105(8)
26.1305(14)
90
90
90
5343.8(5)
4
2.056
2.361
3184
14.0935(8)
10.369(3)
14.526(4)
87.678(4)
81.314(4)
84.639(4)
1271.2(6)
2
8.578(2)
19.423(5)
13.6145(19)
21.232(3)
90
91.129(2)
90
5276.8(14)
16
2.296
˚
b (A)
14.282(4)
27.882(11)
90
˚
c (A)
a (ꢁ)
b (ꢁ)
c (ꢁ)
90
103.294(8)
7527(4)
8
1.87
1.615
3
˚
Volume (A )
Z
Dcalc (g/cm3)
Absorption coefficient (mmꢁ1
F(000)
2.027
2.493
752
)
3.945
3424
4160
Crystal size (mm)
h Range (ꢁ)
0.372 · 0.108 · 0.058
1.44–25.50
ꢁ17 6 h 6 17,
ꢁ17 6 k 6 17,
ꢁ31 6 l 6 31
38548
0.373 · 0.17 · 0.109
1.42–25.12
ꢁ10 6 h 6 10,
ꢁ12 6 k 6 12,
ꢁ17 6 l 6 17
11831
0.251 · 0.186 · 0.037
1.50–25.5
ꢁ23 6 h 6 23,
ꢁ17 6 k 6 17,
ꢁ33 6 l 6 33
36695
0.215 · 0.192 · 0.135
1.87–25.50
ꢁ22 6 h 6 22,
ꢁ16 6 k 6 16,
ꢁ25 6 l 6 25
16699
Index ranges
Reflections collected
Independent reflections
Maximum and minimum
transmission
4803 [Rint = 0.0545]
0.742 and 0.874
3901 [Rint = 0.0332]
0.605 and 0.764
5168 [Rint = 0.0635]
0.702 and 0.944
3695 [Rint = 0.1426]
0.442 and 0.588
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [F2 > 4r(F2)]
5096/0/344
1.266
R1 = 0.0885, wR2 = 0.1749
4443/0/318
1.228
7007/0/461
1.090
R1 = 0.0584, wR2 = 0.1756
4078/0/273
1.083
R1 = 0.0646,
wR2 = 0.1586
R1 = 0.0761,
wR2 = 0.1694
none
R1 = 0.0392,
wR2 = 0.1108
R1 = 0.0425,
wR2 = 0.1132
0.00069(13)
1.580 and ꢁ0.936
R indices (all data)
R1 = 0.0934, wR2 = 0.1773
R1 = 0.0814, wR2 = 0.1954
Extinction coefficient
none
2.118 and ꢁ1.697
none
1.581 and ꢁ0.950
Largestꢁd3ifference peak and hole,
1.299 and ꢁ1.290
˚
e. (A
)
3.64 (t, J = 4.74 Hz, 2H, H2), 3.86 (s, 2H, H3), 7.12 (m, 1H,
H8), 7.17–7.33 (m, 3H, H6, H7 and H9); 13C{1H} (CDCl3,
25 ꢁC): d (vs TMS): 16.09 (SCH3), 48.20 (C3), 48.80 (C1),
56.74 (C2), 125.86 (C7), 127.27 (C6), 128.84 (C4), 129.92
(C9), 130.61 (C8), 138.35 (C5). IR (KBr, cmꢁ1): 3578, 1423
(O–H), 3444,1650 (N–H), 1045 (C–N), 733 (C–S).
line product (Eye and skin irritant), which was filtered,
washed with diethyl ether (10 ml · 4) and dried between
the folds of filter papers. Yield, 70%. m.p. 140 ꢁC. Anal.
Calc. for C10H15NSCl2: C, 51.38; H, 6.90; N, 5.99. Found:
1
C, 57.87; H, 6.68; N, 5.95%. NMR: H(CDCl3, 25 ꢁC): d
(vs TMS): 2.55 (s, 3H, SCH3), 3.25 (t, J = 6.09 Hz, 2H,
H1), 3.90 (t, J = 6,6 Hz, 2H, H2), 4.94 (s, 2H, H3), 7.26–
7.28 (m, 1H, H8), 7.34–7.46 (m, 2H, H6,7), 7þ.72–7.74 (d,
;
13C{1H}
2.6. Synthesis of 3
J = 7.5 Hz, 1H, H9), 10.03 (bs, 2H, NH2
2 (2 g, 10 mmol) was dissolved in 10 ml of dry chloro-
form and cooled in an ice bath. Freshly distilled SOCl2
(5 g, 40 mmol) dissolved in 10 ml of dry chloroform was
added to it dropwise in a period of 15 min. When the addi-
tion was complete the temperature of reaction mixture was
increased slowly and it was stirred under reflux for 6 h.
Thereafter, reaction mixture was cooled and concentrated
to 10 ml on a rotary evaporator to give a light brown solid.
The solid was dissolved in 10 ml of methanol, boiled with a
pinch of activated charcoal and filtered. The filtrate was
treated with 20 ml of diethyl ether. It gave a white crystal-
(CDCl3, 25 ꢁC): d (vs TMS): 16.85 (SCH3), 48.17 (C2),
49.27 (C1), 57.12 (C3), 126.26 (C6), 127.89 (C7 ), 128.87
(C4), 130.25 (C8), 131.50 (C9), 138.95 (C5). IR (KBr,
cmꢁ1): 3415,1569 (N–H), 847 (C–Cl), 763 (C–S).
2.7. Synthesis of L1
2-Methylthiobenzaldehyde (0.5 ml, 4 mmol) dissolved in
10 ml of dry ethanol was stirred for 15 min and 2-(4-meth-
oxyphenyl)telluroethylamine (1.12 g, 4 mmol) dissolved in
10 ml of dry ethanol was added to it. The mixture was

P. Raghavendra Kumar et al. / Inorganica Chimica Acta 361 (2008) 1426–1436
1429
Table 2
Table 2 (continued)
˚
Selected bond lengths (A) and bond angles (ꢁ) of 4, 6, 8 and 9
[Ru(p-cymene)(2-MeS–C6H4–CH2– NHCH2CH2Te-4-C6H4–OMe)]
(PF6)2 (8)
[PdCl(2-MeS–C6H4–CH@NCH2CH2Te–C6H4-4-OMe)]
PF6 Æ CHCl3 Æ 0.5H2O (4)
Pd(1)–N(1)
Pd(1)–S(1)
Pd(1)–Te(1D)
Pd(1D)–Cl(1)
Pd(1D)–Te(1)
Te(1)–C(9)
S(1)–C(1)
C(22)–Ru(1)–S(1)
C(20)–Ru(1)–S(1)
C(18)–Ru(1)–S(1)
C(19)–Ru(1)–Te(1)
C(23)–Ru(1)–Te(1)
C(21)–Ru(1)–Te(1)
S(1)–Ru(1)–Te(1)
C(10)–Te(1)–Ru(1)
C(1)–S(1)–C(27)
98.37(18)
164.34(18)
112.16(19)
120.54(15)
151.83(20)
89.93(15)
90.00(5)
106.05(21)
104.87(38)
113.34(30)
118.96(43)
C(23)–Ru(1)–S(1)
C(21)–Ru(1)–S(1) 127.25(18)
N(1)–Ru(1)–Te(1) 83.82(15)
C(22)–Ru(1)–Te(1) 114.55(16)
C(20)–Ru(1)–Te(1) 92.83(16)
C(18)-Ru(1)–Te(1) 157.54(17)
92.04(20)
2.020(9)
2.341(3)
2.541(25) Pd(1D)–N(1)
2.326(16) Pd(1D)–S(1)
2.483(17) Te(1)–C(10)
2.131(11) Te(1D)–C(10)
Pd(1)–Cl(1)
Pd(1)–Te(1)
2.293(3)
2.534(2)
1.984(18)
2.391(17)
2.113(12)
2.030(28)
1.794(13)
C(10)–Te(1)–C(9)
C(9)–Te(1)–Ru(1)
C(1)–S(1)–Ru(1)
99.30(31)
92.55(22)
99.52(25)
1.79(1)
1.471(14)
S(1)–C(17)
N(1)–C(8)
N(1)–Pd(1)–Cl(1)
Cl(1)–Pd(1)–S(1)
174.07(26)
95.31(11)
87.23(9)
87.11(56)
176.42(58)
89.70(66)
89.44(65)
178.87(78)
N(1)Pd(1)–S(1)
90.26(25)
87.22(25)
177.44(10)
87.42(52)
175.60(89)
93.11(58)
87.72(54)
97.72(42)
89.72(48)
90.58(31)
100.93(54)
104.87(46)
127.70(88)
126.15(73)
C(27)–S(1)–Ru(1)
C(7)–N(1)–Ru(1)
C(8)–N(1)–Ru(1) 114.24(45)
N(1)–Pd(1)–Te(1)
S(1)–Pd(1)–Te(1)
Cl(1)–Pd(1)–Te(1D)
N(1)–Pd(1D)–Cl(1)
Cl(1)–Pd(1D)–S(1)
Cl(1)–Pd(1D)–Te(1)
C(10)–Te(1)–C(9)
C(9)–Te(1)–Pd(1D)
C(9)–Te(1)–Pd(1)
Cl(1)–Pd(1)–Te(1)
N(1)–Pd(1)–Te(1D)
S(1)–Pd(1)–Te(1D)
N(1)–Pd(1D)–S(1)
N(1)–Pd(1D)–Te(1)
S(1)–Pd(1D)–Te(1)
C(10)–Te(1)–Pd(1D) 100.04(49)
C(10)–Te(1)–Pd(1) 100.40(31)
C(10)–Te(1D)–Pd(1) 102.54(106) C(1)–S(1)–C(17)
C(1)–S(1)–Pd(1)
C(17)-S(1)–Pd(1D)
C(8)–N(1)–Pd(1D)
C(8)–N(1)–Pd(1)
Symmetry codes: (i) 1.5ꢁx, y, 1ꢁz; (ii) 1.5ꢁx, 1.5ꢁy, 1.5ꢁz.
[PdCl2(4-MeO–C6H4– TeCH2CH2NH2)] (9)
Pd(1)–N(1)
Pd(1)–Cl(1)
Pd(2)–N(2)
Pd(2)–Cl(4)
Te(1)–C(3)
Te(2)–C1(2)
N(1)–C(1)
N(1)–Pd(1)–Cl(2)
Cl(2)–Pd(1)–Cl(1)
Cl(2)–Pd(1)–Te(1)
N(2)–Pd(2)–Cl(3)
Cl(3)–Pd(2)–Cl(4)
Cl(3)–Pd(2)–Te(2)
C(3)–Te(1)–C(2)
C(2)–Te(1)–Pd(1)
C(12)–Te(2)–Pd(2)
C(6)–O(1)–C(9)
C(1)–N(1)–Pd(1)
N(1)–C(1)–C(2) 110.7(5)
2.059(5)
2.3798(15) Pd(1)–Te(1)
2.056(5) Pd(2)–Cl(3)
2.3744(16) Pd(2)–Te(2)
Pd(1)–Cl(2)
2.2981(15)
2.5101(6)
2.3060(16)
2.5007(6)
2.172(6)
2.104(5)
2.118(6)
1.474(7)
176.43(15)
94.30(6)
88.79(4)
175.88(14)
93.24(6)
88.75(5)
93.3(2)
Te(1)–C(2)
100.30(34)
103.88(59)
113.61(79)
115.19(63)
C(17)–S(1)–Pd(1)
C(7)–N(1)–Pd(1D)
C(7)–N(1)–Pd(1)
Te(2)–C1(1)
2.144(6)
N(1)–Pd(1)–Cl(1)
N(1)–Pd(1)–Te(1)
89.26(15)
87.64(14)
Cl(1)–Pd(1)–Te(1) 176.55(4)
Symmetry codes: (i) x, 0.5 ꢁ y, 1 ꢁ z; (ii) x, y, 1.5 ꢁ z; (iii) x, y, 0.5 ꢁ z.
[PdCl(MeS–C6H4– CH2NH2CH2CH2Te–C6H4-4-OMe)] ClO4.CHCl3 (6)
N(2)–Pd(2)–Cl(4)
N(2)–Pd(2)–Te(2)
90.58(14)
87.43(14)
Cl(4)-Pd(2)–Te(2) 178.00(5)
C(3)–Te(1)–Pd(1) 101.01(16)
C(12)–Te(2)–C(11) 95.8(2)
C(11)–Te(2)–Pd(2) 90.03(18)
C(15)–O(2)–C(18) 116.9(5)
C(10)-N(2)–Pd(2) 118.2(4)
Pd(1)–N(1)
Pd(1)–S(1)
Te(1)–C(9)
S(1)–C(7)
N(1)–C(1)
2.076(8)
2.348(6)
2.113(10) Te(1)–C(10)
1.772(9) S(1)–C(17)
1.485(12) N(1)–C(8)
Pd(1)–Cl(1)
Pd(1)–Te(1)
2.283(5)
2.517(6)
2.117(10)
1.810(12)
1.490(12)
90.16(17)
98.32(16)
119.2(5)
117.6(4)
N(1)–Pd(1)–Cl(1)
Cl(1)–Pd(1)–S(1)
Cl(1)–Pd(1)–Te(1)
C(9)–Te(1)–C(10)
C(10)–Te(1)–Pd(1)
C(7)–S(1)–Pd(1)
C(1)—N(1)—Pd(1)
173.20(21)
95.04(9)
87.35(7)
98.56(32)
99.41(20)
101.55(29)
115.29(55)
N(1)–Pd(1)–S(1)
91.55(21)
86.21(20)
174.99(7)
91.70(24)
103.23(47)
110.51(35)
112.41(52)
N(1)–Pd(1)–Te(1)
S(1)–Pd(1)–Te(1)
C(9)–Te(1)–Pd(1)
C(7)-S(1)–C(17)
C(17)–S(1)–Pd(1)
C(8)—N(1)—Pd(1)
further stirred overnight and then refluxed for 3 h. After
cooling to room temperature, the solvent was evaporated
on a rotary evaporator to obtain L1 as red viscous oil.
Yield 88%; KM = 0.5 cm2 molꢁ1 ohmꢁ1. Anal. Calc. for
1
[Ru(p-cymene)(2-MeS–C6H4–CH2– NHCH2CH2Te-4-C6H4–OMe)]
(PF6)2 (8)
C17H19NOSTe: Te, 30.90. Found: Te, 30.58%. NMR: H
(CDCl3, 25 ꢁC): d (vs TMS): 2.46 (s, 3H, SCH3), 3.15 (t,
J = 7.19 Hz, 2H, H2), 3.78 (s, 3H, OCH3), 4.04 (t,
J = 6.97 Hz, 2H, H1), 6.73–6.76 (d, J = 8.23 Hz, 2H,
Ru(1)–N(1)
Ru(1)–C(22)
Ru(1)–C(20)
Ru(1)–C(18)
Ru(1)–Te(1)
Te(1)–C(9)
S(1)–C(27)
N(1)–C(7)
N(1)–Ru(1)–C(19)
C(19)–Ru(1)–C(22)
C(19)–Ru(1)–C(23)
C(19)–Ru(1)–C(20)
C(23)–Ru(1)–C(20)
C(19)–Ru(1)–C(21)
C(23)–Ru(1)–C(21)
N(1)–Ru(1)–C(18)
C(22)–Ru(1)–C(18)
C(20)–Ru(1)–C(18)
N(1)–Ru(1)–S(1)
2.163(10) Ru(1)–C(19)
2.184(6)
2.218(8)
2.248(7)
2.376(2)
2.126(7)
1.767(9)
1.491(11)
2.213(9)
2.221(7)
2.251(7)
2.630(6)
2.134(12) S(1)–C(1)
1.773(10) N(1)–C(8)
1.495(10)
Ru(1)–C(23)
Ru(1)–C(21)
Ru(1)–S(1)
Te(1)–C(10)
H
12,14), 7.19–7.23 (m, 2H, H8), 7.25–7.39 (m, 1H, H6,7),
7.70–7.73 (d, J = 8.27 Hz, 1H, H11,15), 7.78–7.80 (d,
J = 7.49 Hz, 1H, H9), 8.70 (s, 1H, H3); 13C{1H} (CDCl3,
25 ꢁC): d (vs TMS): 10.07 (C2), 16.59 (SCH3), 54.90
(OCH3), 62.53 (C1), 100.49 (C10), 114.92 (C12,14), 125.16
(C6), 126.87 (C8), 128.16 (C9), 130.54 (C7), 133.71 (C4),
139.10 (C5), 140.77 (C11,15), 159.23 (C3,13). IR (KBr,
cmꢁ1): 1633, 1585 (C@N), 1243 (C–N), 1283(C–O),
753(C–S), 473, 515(C–Te(alkyl)), 295 (C–Te(aryl)).
88.15(22)
78.68(24)
66.07(25)
36.85(24)
78.31(25)
67.05(23)
66.73(25)
93.91(22)
67.41(25)
66.89(25)
85.56(16)
N(1)–Ru(1)–C(22)
161.07(22)
124.35(25)
110.05(22)
66.50(24)
146.68(21)
36.66(23)
37.44(24)
37.00(22)
36.93(26)
79.71(24)
147.93(17)
N(1)–Ru(1)–C(23)
N(1)–Ru(1)–C(20)
C(22)–Ru(1)–C(20)
N(1)–Ru(1)–C(21)
C(22)–Ru(1)–C(21)
C(20)–Ru(1)–C(21)
C(19)–Ru(1)–C(18)
C(23)–Ru(1)–C(18)
C(21)–Ru(1)–C(18)
C(19)–Ru(1)–S(1)
2.8. Synthesis of L2
Method I: Bis(4-methoxyphenyl)ditelluride (0.50 g,
1.0 mmol) was dissolved in 50 ml of dry ethanol and the

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P. Raghavendra Kumar et al. / Inorganica Chimica Acta 361 (2008) 1426–1436
3
3
9
9
6
1
1
4
5
4
5
OH
OH
NaBH4
dry EtOH
-H2O
O
8
7
N
8
7
N
OH
2
2
+
H
H2N
dry EtOH
SMe
SMe
SMe
6
2
1
3
9
6
1
SOCl2
CHCl3
4
5
Cl
8
7
N
.HCl
2
H
SMe
3
1
N
3
9
6
11
14
4
5
10
Te
12
13
OMe
dry EtOH
-H2O
8
1
O
Te
3
4
8
7
7
+
2
H2N
2
SMe
15
SMe
6
OMe
MeO
L1
5
dry EtOH
NaBH4
3
9
11
1
4
10
Te
12
13
OMe
EtOH
NaBH4, NaOH
3
8
N
H
2
2
MeO
Te2
TeNa
7
EtOH
2
15
SMe
5
14
6
L2
Scheme 1.
solution was refluxed for 1 h under dry nitrogen atmo-
sphere. A solution of sodium borohydride made in NaOH
(5%) was added dropwise to the refluxing solution slowly
under nitrogen atmosphere until it became colourless due
to the formation of ArTeꢁNa+. (2-Chloroethyl)[2-(meth-
ylsulfanyl)benzyl]ammonium chloride (3) (0.253 g, 1 mmol)
dissolved in 10 ml of ethanol was added to this colourless
solution with constant stirring. The resulting reaction mix-
ture was refluxed further for 2 h. It was cooled to room
temperature and poured into 100 ml of ice-cold distilled
water. The aqueous solution was neutralized with 1–2 M
NaOH solution. The ligand L2 was extracted into 100 ml
of chloroform from this aqueous mixture. The chloroform
extract was washed with water (50 ml · 4) and dried over
anhydrous sodium sulfate. On removing chloroform with
a rotary evaporator, L2 was obtained as red viscous oil.
Yield: 75%.
2.47 (s, 3H, SCH3), 2.96–3.02 (m, 4H, H1,2), 3.78 (s,3H,
OCH3), 3.85 (s, 2H, H3), 6.71–6.74 (d, J = 8.4 Hz, 2H,
H
12,14), 7.11–715 (m, 1H, H8), 7.23–7.26 (m, 3H, H6,7,9),
7.66–7.66 (d, J = 8.41 Hz, 2H, H11,15 ); 13C{1H} (CDCl3,
25 ꢁC): d (vs TMS): 10.06 (C2), 15.33 (SCH3), 49.19 (C1),
54.69 (OCH3), 50.45 (C3), 100.07 (C10), 114.92 (C12,14),
124.42 (C9), 125.14 (C6), 128.51 (C4), 129.26 (C7), 131.71
(C8), 140.56 (C11,15 ), 140.99 (C5), 159.26 (C13) IR (KBr,
cmꢁ1) 3302, 1586, 821 (N–H) 1287, 1247 (C–N), 1177
(C–O), 749, 676 (C–S), 473, 515 (C–Te(alkyl)), 290 (C–
Te(aryl)).
2.9. Synthesis of [PdCl(L1)]PF6 Æ CHCl3 Æ 0.5 H2O (4)
Na2[PdCl4] (0.294 g, 1 mmol) was dissolved in 2 ml of
distilled water. The solution of L1 (0.413 g, 1 mmol) made
in 20 ml of acetone was added to it with vigorous stirring.
The solution was stirred further for 1/2 h at room temper-
ature and poured into 50 ml of distilled water. The complex
was extracted into 50 ml of chloroform. The chloroform
extract was dried with anhydrous sodium sulfate and sol-
vent was evaporated on a rotary evaporator to yield an
orange solid. The solid was dissolved in a 1:1 mixture of
chloroform and methanol and mixed with a solution of
potassium hexafluorophosphate (0.187 g, 1 mmol) dis-
solved in 10 ml of acetone. The mixture was stirred for
3 h and filtered. The solvent was evaporated off on a rotary
evaporator, resulting in a yellow solid. The single crystals
of 4 were grown by slow evaporation of its solution in
methanol and chloroform mixture (1:1). Yield 61%; m.p.
125(d) ꢁC. KM = 155 cm2 molꢁ1 ohmꢁ1. Anal. (Powder
Method II: L1 (0.4127 g, 1 mmol) was dissolved in 20 ml
of dry ethanol and the solution cooled in an ice bath. Solid
NaBH4 (0.38 g, 10 mmol) was added with stirring in small
lots within 15 min. The reaction mixture was refluxed for
4 h and cooled to room temperature. Using a rotary evap-
orator, solvent was removed giving a semisolid, which was
leached with dry dichloromethane (25 ml · 4). The result-
ing dichloromethane extract was washed with distilled
water (50 ml · 3) and dried with anhydrous sodium sulfate.
The L2 was obtained as red viscous oil, when dichloro-
methane from this dried extract was removed on a rotary
evaporator. Yield 90%; KM = 0.8 cm2 molꢁ1ohmꢁ1. Anal.
Calc. for C17H21NOSTe: Te, 30.75. Found: Te, 30.55%.
1
NMR: H (CDCl3, 25 ꢁC): d (vs TMS): 1.89 (s, 1H, NH),

P. Raghavendra Kumar et al. / Inorganica Chimica Acta 361 (2008) 1426–1436
1431
form) Calc. for C17H19ClF6NOPPdSTe: C, 29.18; H, 2.74;
N, 2.00; Te, 18.23. Found: C, 28.55; H, 2.48; N, 2.20; Te,
18.68%. NMR: H (DMSO-d6, 25 ꢁC): d (vs TMS): 2.65
Anal. (Powder form) Calc. for C17H21Cl2NO5PdSTe: C,
31.11; H, 3.22; N, 2.13; Te, 19.44. Found: C, 31.53; H,
1
1
3.37; N, 2.23; Te, 20.10%. NMR: H (CDCl3, 25 ꢁC): d
(bs, 1H, H2), 2.81 (bs, 1H, H2), 3.06 (s, 3H, SCH3), 3.78
(s,3H, OCH3), 4.56 (bs, 1H, H1), 5.53 (bs, 1H, H1), 7.02–
7.05 (d, J = 6.82 Hz, 2H, H12,14), 7.80–7.83 (m,, 2H, H8),
7.94–7.99 (m, 1H, H6,7,9), 8.11–8.14 (d, J = 7.49 Hz, 1H,
(vs TMS): 2.17 (bs, 1H, NH), 2.92 (s, 3H, SCH3), 3.38–
3.50 (m, 2H, H2), 3.97–4.02(m, 2H, H1), 3.77 (s, 3H,
OCH3), 5.53–5.56 (d, 2H, H3), 6.93–6.96 (d, J = 8.66 Hz,
2H, H12,14), 7.46–7.48 (m, 1H, H8), 7.47–7.60 (m, 3H,
H
11,15), 9.02 (s, 1H, H3); 13C{1H} (DMSO-d6, 25 ꢁC): d
H
6,7,9), 7.82–7.85 (d, J = 8.51 Hz, 2H, H11,15 ); 13C{1H}
(vs TMS): 16.34 (C2), 23.84 (SCH3), 55.37 (OCH3), 74.35
(C1), 105.73 (C10), 115.79 (C12,14), 130.66 (C6), 131.40
(C8), 135.41 (C9), 137.27 (C7), 124.53 (C4), 133.70 (C5),
(CDCl3 + DMSO-d6 (20%), 25 ꢁC): d (vs TMS): 17.39
(C2), 16.70 (SCH3), 55.92 (C1), 55.31 (OCH3), 64.45 (C3),
104.83 (C10), 115.76 (C12,14), 124.47 (C9), 126.26 (C6),
129.28 (C4), 131.02 (C7), 133.85 (C8), 137.82 (C11,15),
138.56 (C5), 161.45 (C13). IR (KBr, cmꢁ1) 3437(b), 1590
(N–H) 3028 (ArC–H), 1258 (C–N), 1111, 1048, 555
(ClO4), 708 (C–S), 513 (C–Te(alkyl)), 280 (C–Te(aryl)).
138.09 (C11,15), 161.09 (C13), 164.73 (C3). IR (KBr, cmꢁ1
)
1628, 1581 (C@N), 848 (P–F), 780 (C–S), 518 (C–Te(alkyl))
291(C–Te (aryl)).
2.10. Synthesis of [PtCl(L1)]PF6 (5)
2.12. Synthesis of [PtCl(L2)]ClO4 (7)
The solution of K2[PtCl4] (0.105 g, 0.25 mmol) made in
2 ml of distilled water was treated with a solution of L1
(0.104 g, 0.25 mmol) made in 10 ml of acetone as described
for 4. Using the workup similar to that of 4, an orange solid
5 was obtained. It was dissolved in 10 ml of methanol and
mixed with a solution of potassium hexafluorophosphate
(0.187 g, 1 mmol) dissolved in 10 ml of acetone. The mix-
ture was stirred for 3 h and filtered. The solvent was evapo-
rated off on a rotary evaporator to yield a yellow solid. The
crystals of 5 were grown by slow evaporation of its solution
in a mixture of DMSO and chloroform (1:9). Yield 61%;
m.p. 181 ꢁC (d). KM = 145.5 cm2 molꢁ1 ohmꢁ1. Anal. Calc.
for C17H19NOTeSClPtPF6: C, 25.90; H, 2.42; N, 1.78; Te,
16.18. Found: C, 26.10; H, 2.53; N, 1.84; Te, 17.01%.
K2[PtCl4] (0.294 g, 1 mmol) dissolved in 5 ml of dry
methanol was treated with the solution of L2 (0.415 g,
1 mmol) made in 10 ml of methanol as described for 6. Fur-
ther reaction with silver perchlorate (0.208 g, 1 mmol) dis-
solved in 10 ml of dry methanol and a workup as
mentioned in the case of 6 gave an orange-red solid 7. Its
crystals were grown from a 1:1 mixture of chloroform and
hexane by slow evaporation of the solvent at room
temperature. Yield 67%; m.p. 126 ꢁC (d). KM
=
144.5 cm2 molꢁ1 ohmꢁ1. Anal. Calc. for C17H21Cl2NO5-
PtSTe: C, 27.41; H, 2.84; N, 1.88; Te, 17.13. Found: C,
1
28.51; H, 2.97; N, 1.96; Te, 16.54%. H (CDCl3, 25 ꢁC): d
(vs TMS): 2.50 (s, 1H, NH), 2.95 (s, 3H, SCH3), 3.40–3.48
(m, 2H, H2), 3.94–4.03(m, 2H, H1), 3.80 (s, 3H, OCH3),
5.55–5.57 (d,, 2H, H3), 6.93–6.97 (d, J = 8.46 Hz, 2H,
1
NMR: H (DMSO-d6, 25 ꢁC): d (vs TMS): 2.64 (bs, 1H,
H2), 2.79 (bs, 1H, H2), 3.01 (s, 3H, SCH3), 3.78 (s, 3H,
OCH3), 4.53 (bs, 1H, H1), 5.55 (bs, 1H, H1), 7.02–7.05 (d,
J = 6.82 Hz, 2H, H12,14), 7.80–7.83 (m, 1H, H8), 7.94–8.00
(m, 1H, H6,7,9), 8.11–8.16 (d, J = 7.49 Hz, 1H, H11,15),
9.00 (s, 1H, H3); 13C{1H} (DMSO-d6, 25 ꢁC): d (vs TMS):
16.34 (C2), 23.84 (SCH3), 55.37 (OCH3), 74.35 (C1),
105.73 (C10), 115.79 (C12,14), 130.66 (C6), 131.40 (C8),
135.41 (C9), 137.27 (C7), 124.53 (C4), 133.70 (C5), 138.09
(C11,15), 161.09 (C13), 164.73 (C3). IR (KBr, cmꢁ1): 1582
(C@N), 842 (P–F), 710 (C–S), 512 (C–Te((alkyl)), 280 (C–
Te(aryl)).
H
H
12,14), 7.51 (t, J = 5.52 Hz, 1H, H8), 7.56–7.68 (m, 3H,
6,7,9), 7.93–8.18 (d, J = 8.51 Hz, 2H, H11,15). IR (KBr
cmꢁ1): 3437(b), 1580 (N–H), 3028 (ArC–H), 1101,
1046, 555 (ClO4), 730 (C–S), 507 (C–Te(alkyl)), 290
(C–Te(aryl)).
2.13. Synthesis of [Ru(p-cymene)(L2)](PF6)2 Æ CHCl3 (8)
[RuCl2(p-cymene)]2 (0.061 g, 0.1 mmol) was dissolved in
5 ml of dry dichloromethane. The solution of L2 (0.083 g,
0.2 mmol) also made in 10 ml of dichloromethane was
added to it with vigorous stirring. The reaction mixture
was stirred further for 1/2 h at room temperature and
KPF6 (0.035 g, 0.2 mmol) dissolved in 10 ml of acetone
was added. The mixture was stirred further for 2 h and fil-
tered through Celite. The solvent of filtrate was evaporated
on a rotary evaporator to obtain 8. Yellow coloured flaky
crystals of 8 were obtained by slow evaporation of its solu-
tion made in a 1:2 mixture of chloroform and hexane. Yield
63%; m.p. 145 ꢁC (d). KM = 244.6 cm2 molꢁ1 ohmꢁ1; Anal.
(Powder form) Calc. for C27H35F12NOP2RuSTe: C, 34.25;
H, 3.59; N, 1.45; Te, 13.27. Found: C, 34.49; H, 3.75; N,
2.11. Synthesis of [PdCl(L2)]ClO4 Æ CHCl3 (6)
Na2[PdCl4] (0.294 g, 1 mmol) was dissolved in 5 ml of
dry methanol and mixed with a solution of L2 (0.415 g,
1 mmol) made in 10 ml of methanol with vigorous stirring.
The mixture was stirred further for 1/2 h at room temper-
ature and silver perchlorate (0.208 g, 1 mmol) dissolved in
10 ml of dry methanol was added. It was again stirred for
1 h and the resulting precipitate was filtered through Celite.
The solvent from the filtrate was removed on a rotary evap-
orator to yield an orange solid. The single crystals of 6 were
obtained from a mixture (2:1) of chloroform and hexane.
1
1.49; Te, 13.57%. NMR: H (CDCl3, 25 ꢁC): d (vs TMS):
Yield 60%; m.p 110 ꢁC (d). KM = 134.8 cm2 molꢁ1 ohmꢁ1
.
1.41 (d, J = 6.6 Hz, 6H, CH3 of i-pr), 1.91 (s, 3H, CH3 p

1432
P. Raghavendra Kumar et al. / Inorganica Chimica Acta 361 (2008) 1426–1436
to i-pr), 2.45 (sp, 1H, CH of i-pr), 2.85 (s, 3H, SCH3), 3.30
(bs, 2H, H2), 3.51 (m, 2H, H1), 3.83 (s, 3H, OCH3), 4.2 (bs,
2H, H3), 5.85–6.10 (m, 4H, Ar–H of p-cymene), 6.75 (m,
3H, H7,12,14), 6.94 (d, J = 8.7 Hz, 1H, H9), 7.10–7.32 (m,
1H, H8), 7.45–7.61 (m, 2H, H6,11,15), 8.14 (bs, 1H, NH).
IR (KBr, cmꢁ1): 3424(b) 1578 (N–H), 3028 (ArC–H),
750(C–S), 844(P–F), 511(C–Te(alkyl)), 285 (C–Te(aryl)).
(see Section 2.14). It is authenticated by NMR and X-
ray diffraction on its single crystal.
1
3.1. H and 13C {1H} NMR spectra
The L1 and L2 give characteristic 1H and 13C {1H}
1
NMR spectra [36]. In H NMR spectra of complexes 4–8
the signal of SCH3 protons is deshielded (with respect to
2.14. Synthesis of [PdCl2(NH2CH2CH2Te–
C6H4-4- OMe)] (9)
those of free ligand) by ꢂ0.5 ppm, indicating the coordina-
1
tion of metal by sulfur. In the H NMR spectra of 4 and 5
the protons of N/TeCH2 become chemically non-equiva-
lent to give four signals. The signals due to NCH2 protons
were found deshielded (0.5–1.5 ppm) whereas those of
TeCH2 appeared shielded (0.2–0.4 ppm). However, the for-
mation of metal–tellurium bond in 4 is established by its
single crystal structure unequivocally. Carbon-13 NMR
spectra of both 4 and 5 indicate the formation of metal –
Te bond in the two complexes as carbon atoms attached
to Te show signals deshielded upto 6.3 ppm with respect
to those of the free ligand. The formation of metal–nitro-
gen bond in 4 and 5 is also supported by deshielding (with
respect to that of free ligand) of –HC@N– signal in their
proton (upto 0.3 ppm) and carbon-13 (5 ppm) NMR spec-
The Na2[PdCl4] (0.294 g, 1 mmol) was dissolved in 5 ml
of distilled water. The solution of 2-(4-methoxyphenyltell-
uro)ethylamine (0.279 g, 1 mmol) made in 10 ml of acetone
was added to it with vigorous stirring. The stirring was
continued further for 2 h, which gave an orange coloured
precipitate of 4. It was filtered and dried. Its recrystalliza-
tion from a mixture of chloroform (5 ml) and DMF
(1 ml) gave red crystals of 4. Yield 68%; m.p. 145 ꢁC (d),
Anal. Calc. for C9H13NOPdTeCl2: C, 23.70; H, 2.87; N,
3.07; Te 27.98. Found: C, 23.87; H, 2.66; N, 3.45; Te,
1
27.78%. NMR: H (DMSO-d6 25 ꢁC): d (vs TMS), 3.30
(bs 1H, H1) 3.80 (s, 3H, OCH3), 4.11 (bs, 1H, H1), 4.80
(bs, 1H, H2), 5.01(bs, 1H, H2), 7.04–7.07 (d, J = 8.52 Hz,
2 H, H5,7), 8.04–8.06 (d, J = 8.40 Hz, 2H, H4,8), 8.50
(NH2); 13C (DMSO-d6, 25 ꢁC): d (vs TMS): d 19.62 (C2),
50.25 (C1), 55.33 (OCH3), 106.13, (C3), 115.64 (C5,7),
138.04 (C4,8), 160.73 (C6).
1
tra. In H NMR spectra of 6 and 7 the signals of H3 pro-
tons become a doublet because the two protons become
chemically nonequivalent due to the rigidity imposed by
chelation of the ligand. On comparing proton NMR spec-
tra of complexes 6–8 with that of free L2, it has been found
that the N/TeCH2 signals are deshielded (1.0/0.4 ppm) with
respect to those of the free ligand. Moreover, deshielding in
the signals of ArH (o to Te), NH and ArCH2 has been
found to be of the order 0.2, 0.9 and 1.6 ppm, respectively.
These observations have been further corroborated by car-
bon-13 NMR spectrum, as ArCH2, NCH2 and TeCH2 sig-
nals in the spectrum of 6 appear deshielded by 11.0, 7.0 and
7.3 ppm, respectively, with respect to those of the free
ligand. The 13C{1H} NMR of 7 and 8 could not be
recorded due to their inadequate solubility. The deshielding
of aryl proton signals of tellurated ethyl amine when it
coordinates with Pd giving 9 has been found to be 0.3–
0.4 ppm. This is corroborated by 13C{1H} NMR spectrum
of 9. The signals of carbon atoms attached to N or Te are
deshielded up to ꢂ7 ppm with respect to those of the free
ligand [30].
3. Results and discussion
The reactions involved in the synthesis of ligands L1 and
L2 are shown in Scheme 1. Both ligands are stable viscous
liquids under ambient conditions and soluble in common
organic solvents except hexane.
The complexes of L1 with Pd(II) and Pt(II) and of L2
with Pd(II), Pt(II) and Ru(II) are also stable under ambi-
ent conditions and soluble in DMSO. In other common
organic solvents, the Pd(II) and Pt(II) complexes of L1
show limited solubility, but those of L2 are more soluble
than those of L1. In methanol and chloroform the solubil-
ity of complexes of L1 is moderate. However, Ru(II) com-
plex of L2 is soluble in common organic solvents except
hexane and diethyl ether. All complexes of L1 and L2are
electrolytes (1:1 in the case of Pd/Pt; 1:2 for Ru). The
ꢁ
IR bands resulting from ClO4 indicate that the anion is
3.2. Crystal structures
uncoordinated [35]. The Te–C(alkyl) bands appear at
higher frequencies than those of Te–C(aryl) bands. The
m(C@N) of L1 undergoes a small red shift ꢂ5 cmꢁ1 on
complex formation. The product of the reaction of
PdCl2(C6H5CN)2 (in chloroform) or Na2PdCl4 ( in water)
with L1( in acetone) if not treated with NaPF6 and left for
crystallization in a mixture of chloroform and DMF
(5:1), results in red crystals of [PdCl2(4-MeO–C6H4–
TeCH2CH2NH2)] (9) due to hydrolysis of Schiff base. 9
may also be synthesized by vigorously stirring (for 2 h)
Na2[PdCl4] with 2-(4-methoxyphenyltelluro)ethylamine
Single crystals of 4, 6, 8 and 9 were found good for X-
ray diffraction and their single crystal structures were
solved. The twinning in the crystals of complex 5 restricted
us from proceeding further in solving its structure.
The molecular structure of 4 is shown in the Fig. 1. The
selected bond lengths and bond angles are given in the
Table 2. This is among the first two structurally character-
ized Pd(II) complexes of a (Te, N, S) ligand (other one is 6
described below) There is one molecule of CHCl3 and
0.5 molecule of H2O per molecule of 4 in the lattice. The

P. Raghavendra Kumar et al. / Inorganica Chimica Acta 361 (2008) 1426–1436
1433
respectively. There are two asymmetric Pd and Te atoms
Cl5
C5l
in the lattice of crystal 4. Between the two molecules of 4
F6
˚
there are intra [3.334(3) A] and inter molecular
˚
F5
[3.500(3) A] Teꢀ ꢀ ꢀCl secondary interactions. Also there
F6
F7
C2S
C9
Te1
˚
are intermolecular Pdꢀ ꢀ ꢀTe [3.621(2) A] secondary interac-
Cl6
C16
F4
tions (Fig. 2), which we have observed for the first time.
The geometry of Pd(II) is square planar. The hypervalent
nature of tellurium makes the Pdꢀ ꢀ ꢀTe as well as the
Teꢀ ꢀ ꢀCl secondary interaction possible.
P2
C11
C12
C8
N1
C10
F4
C7
O1
C13
C14
C6
C15
C5
C4
The ORTEP diagram of 6 is shown in Fig. 3. The
selected bond lengths and bond angles are given in Table
2. The crystal contains a molecule of CHCl3 per molecule
of 6. With 4 it makes the first two structurally characterized
Pd(II) complexes of (Te, N, S) type hybrid organotellurium
ligands. The Pd–S, Pd–Te, Pd–N and Pd–Cl bond lengths
C17
Pd1
C1
S1
C3
Cl1
C2
˚
are 2.348(6), 2.517(6), 2.076(8) and 2.283(5) A, respectively,
Fig. 1. ORTEP diagram of [PdCl(2-MeS–C6H4–CH@NCH2CH2Te–
C6H4-4-OMe)]PF6 Æ CHCl3 Æ 0.5H2O (4) with 50% thermal ellipsoids;
water molecule has not been shown for clarity.
and consistent with earlier reported values [20,37,38] dis-
˚
cussed above. However, Pd–Te bond length 2.517(6) A is
shorter than the value observed for 4 as well as the sum
˚
Pd–Te, Pd–Cl and Pd–N bond lengths (2.534(2), 2.293(3)
and 2.020(9) A, respectively) are consistent with the values
of covalent radii 2.65 A. Probably the reduction of
>C@N– makes the skeleton of L2 more flexible than that
of L1 and consequently large size Te atom makes a stronger
bond with Pd. The Pd–S, Pd–N and Pd–Cl bond lengths
(Table 2) are also closer to the sum of covalent radii men-
tioned above. In complex 6 also there is a square planar
geometry around Pd(II). In both 4 and 6, Te is trans to S
but Pd–S bond distance is not significantly influenced by
the trans influence of Te.
The molecular structure of 8 is shown in Fig. 4. The
selected bond lengths and bond angles are given in Table
2. 8 is the first structurally characterized complex, in which
coordination sphere of Ru(II) is completed by p-cymene
ring and a tridentate hybrid organotellurium ligand of
(Te, N, S) type. The crystal contains a molecule of CHCl3
˚
reported’ for [PdCl{4-MeOC6H4TeCH2CH2N@C(CH3)–
ꢁ
˚
C6H4-2-O }] [20] viz. 2.504(1), 2.290(4) and 2.01(1) A,
respectively. For Pd(II) complex of N-{2-(4-methoxyphe-
nyltelluro)ethyl}pyrrolidine [37] Pd–Te, Pd–Cl and Pd–N
bond lengths have been reported as 2.478(3), 2.3160(7)–
˚
2.3915(7) and 2.086(2) A, respectively. On comparing these
values with those of 4 the difference appears larger in case
of Pd–Cl. It probably accrues due to trans influence of Te.
For cis-[Pd{C6H5CH@NCH2–CH2–SEt}Cl2] [38] Pd–S,
Pd–N and Pd–Cl bond distances are reported as
2.255(1)–2.421(2),
2.312(1) A, respectively, and appear to be consistent with
those of 4. The Pd–Te bond length, 2.534(2) A in 4 is
shorter than the sum of covalent radii 2.65 A, indicating
1.992(4)–2.038(2)
and
2.296(1)–
˚
˚
ꢁ
˚
and there are two PF6 ions per molecule of 8. Ru has an
a strong coordination of Te with Pd. The Pd–Cl, Pd–N,
and Pd–S bond lengths (Table 2) are closer to the corre-
sponding sum of covalent radii (2.27, 1.98 and 2.32 A),
octahedral geometry. The Ru–Te, and Ru–N bond lengths
(2.630(6) and 2.163(10) A, respectively) are consistent with
the reported values 2.4983(8)–2.6371(4) and 2.041(6)–
˚
˚
N1
S1
Pd1
3.621(2) Å
Te1
Cl1
3.500(3) Å
Te1
3.334(3) Å
Cl1
Pd1
N1
S1
Fig. 2. Intra intermolecular Teꢀ ꢀ ꢀCl and inter molecular Pdꢀ ꢀ ꢀTe secondary interactions in [PdCl(2-MeS–C6H4-CH@NCH2CH2Te–C6H4-4-OMe)]PF6 (4)
ꢁ
PF6 ion CHCl3, H2O molecules and H atoms have been omitted for clarity).

1434
P. Raghavendra Kumar et al. / Inorganica Chimica Acta 361 (2008) 1426–1436
˚
plex 8, 2.376(2) A, is consistent with this report, however,
O1S
its Ru–N bond length is longer. The ligand in 8 is not a
Schiff base but its reduced product. This may be one of
the possible reasons for the difference. Moreover, the M–
L bond lengths (Ru–S, Ru–Te and Ru–N) of 8 are some-
what longer (Table 2) than the sum of the corresponding
Cl2
O4S
O2S
C17
O3S
Cl1
˚
covalent radii 2.24, 2.61 and 1.94 A, respectively. The bond
C12
S1
lengths and angles of p-cymene group have been found
normal. The Ru–C bond lengths (Table 2) are almost sim-
ilar and consistent with the earlier reports [36]. In all com-
plexes, 4, 6, and 8, the bond angles and bond lengths of
benzene ring and the organic skeleton of the ligands have
been found to be normal. The molecular structure of 9 is
shown in Fig. 5. There are two asymmetric molecules in
the crystal. Pd has square planar geometry. The methyl
group attached to sulfur and 4-methoxy group attached
to Te are cis to each other. The Pd–Cl bond trans to Te
is somewhat longer than the other Pd–Cl bond length
(Table 2) due to the strong trans influence of Te. The
Pd–N and Pd–Te bond lengths are consistent with the
recently reported values [2.086(2)–2.01(1), 2.4781(3)–
O1
C6
C7
C11
C10
Pd1
C16
C5
Te1
C9
C13
C14
C2
C4
C15
C3
C1
N1
C8
Fig. 3. ORTEP diagram of [PdCl(MeS–C6H4–CH2NH2CH2CH2Te–
C6H4-4-OMe)]ClO4 Æ CHCl3 (6) with 50% probability ellipsoids (CHCl3
molecule has been omitted for clarity).
C25
˚
2.504(1) A, respectively] for chelates of Pd(II) formed with
C23
C22
C20
C18
C19
C24
C21
(Te, N) and (Te, N, O) ligands [20,37]. Between the neigh-
bouring molecules of 9 there are Teꢀ ꢀ ꢀCl secondary interac-
tions (Fig. 6). This is probably due to hypervalent nature of
C17
C26
C3
˚
C2
tellurium. The Pd–Pd distance is 3.37(6) A, which is greater
Ru1
˚
C27
than the sum of van der Waal’s radii of Pd, 3.26 A. There
C1
C4
C5
exist C–Hꢀ ꢀ ꢀp interactions (Fig. 3) also in the crystal of 9.
On comparing Pd–N and Pd–Te bond distances of 9 with
those of a palladium complex, [PdCl2L] (L = (4-ethoxy-
phenyl) [2-amino-5-methyl)phenyl]telluride [41] in which
skeleton containing Te and N donor sites is aromatic
N1
Te1
S1
C15
C6
C8
C7
C10
C14
C13
C9
(Pd–Te = 2.4698(5) Pd–N = 2.045(5), Pd–Cl = 2.301(2)/
˚
C11
2.371(1) A), it appears that Pd–Te distance of
9
˚
C16
(2.5101(6) A) is somewhat longer but Pd–N and Pd–Cl
bond lengths (Table 2) are consistent. This is surprising
because aromatic system is expected to reduce the donor
character of nitrogen.
C12
O1
Fig. 4. ORTEP diagram of [Ru(p-cymene)(2-MeS–C6H4–CH2NHCH2-
CH2Te-4-C6H4OMe)] ðPF6Þ2 Æ CHCl3 (8) with 30% probability ellipsoids
ꢁ
(the PF6 anions, CHCl3 molecule and H atoms have been omitted for
clarity).
C9
˚
2.142(3) A, respectively, for [(Ru(p-cymene)Cl(H2NCH2-
C18
O1
CH2TeC6H4-4-OCH3)] and [Ru(ꢁO-2- C6H4C(Me)NH-
CH2CH2TeC6H4-4-OMe)2] [21] For complexes [Ru(PPh3)-
(CH3CN)Cl(2-(Ph2P)C6H4CH@N(CH2)2OH)]Cl, [RuCl2-
(2-(Ph2P)C6H4CH@N– CH(Me)CH(Ph)OH)(PPh3)] and
Ru(CH3CN)2(2-(Ph2P)C6H4CH@NCH(Et)CH2OH) PPh3)]-
(BF4)2 [39] Ru–N bond distance is reported between
O2
C6
C14
C15
C16
C5
C4
C7
C1
C13
C8
C3
Cl3
Pd2
C2
C17
˚
Cl4
C12
2.00(1)–2.127(9) A, some what shorter than that of 8. Prob-
ably the steric influence of Te in complex 8 makes this
difference. In the case of complexes [RuCl2L] (L = N,N0-
bis(2-tert-butylthiobenzilidene)-1,3-propanediamine) and
[RuCl(CH3CN)(L)] (N,N0-bis(2-tert-butylthiobenzilidene)-
1,2-ethylenediamine) the Ru–S and Ru–N distances [40]
are reported between 2.3436(7)–2.3737(8) and 2.032(3)–
N1
Te1
Te2
C10
C11
Pd1
Cl1
N2
Cl2
Fig. 5. ORTEP diagram showing two asymmetric molecules of complex
[PdCl2(2-MeO–C6H4–TeCH2CH2NH2)] (9) with 30% thermal ellipsoids.
˚
2.053(2) A, respectively. The Ru–S bond distance of com-

P. Raghavendra Kumar et al. / Inorganica Chimica Acta 361 (2008) 1426–1436
1435
3.451(4) Å
Cl2
Te1
H9A
2.828(2) Å
Cl1
Pd1
Te1
Pd1
Cl2
N1
Cl1
2.776(2) Å
H1C
N1
Te1
Pd1
Cl1
Cl2
Fig. 6. Teꢀ ꢀ ꢀCl and CHꢀ ꢀ ꢀp secondary interactions in [PdCl2(2-MeO–C6H4–TeCH2CH2NH2)] (9) (Some of the H atoms have been omitted for clarity).
4. Conclusions
Crystallographic Data Centre via www.ccdc.cam.ac.uk/
data_request/cif. Supplementary data associated with this
article can be found, in the online version, at
doi:10.1016/j.ica.2007.09.012.
The first examples of (Te, N, S) ligands, 2-CH3S-
C6H4CH@NCH2CH2TeC6H4-4-OCH3 (L1) and 2-CH3-
SC6H4CHNHCH2CH2TeC6H4-4-OCH3 (L2), and their
complexes with Pd(II), Pt(II) and Ru(II) have been synthe-
sized. The mode of bonding of L1 and L2 with Pd(II) and
Ru(II) has been shown to be (Te, N, S) by single crystal
structure determination. The tendency of Te to exhibit
hypervalence results in Teꢀ ꢀ ꢀCl and Pdꢀ ꢀ ꢀTe secondary inter-
actions, which are not much investigated so far. [PdCl2-
(4-MeO–C6H4– TeCH2CH2NH2)] (9) has been formed due
the hydrolysis of Schiff base, when attempts were made to
grow crystals of a Pd-complex of L1. 9 has also been synthe-
sized by the reaction of an appropriate tellurated amine and
PdCl2 and characterized by X-ray diffraction on its single
crystal.
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