First structurally characterized complex of an acyclic tellurated Schiff base [4-MeOC6H4TeCH2CH2N=C(CH 3)C6H4-2-OH (L1H)] having metal-tellurium bond; Synthesis and crystal structure of [PdCl(L1)]

Article abstract of DOI:10.1016/j.inoche.2004.02.001

Acyclic tellurated Schiff base [4-MeOC₆H₄TeCH ₂CH₂N=C(CH₃)C₆H₄-2-OH (L¹H)] has been synthesized by reacting 2-(4-methoxyphenyltelluro) ethylamine with o-hydroxyacetophenone. The L¹H on reaction with Na₂PdCl₄ forms a complex [PdCl(L¹)] in which the tellurated Schiff base coordinates in a tridentate mode. The proton and carbon-13 NMR spectra of L¹H and the complex are characteristic. The single crystal structure of the complex is solved. The Pd-Te, Pd-Cl, Pd-O and Pd-N bond distances are 2.504(1), 2.290(4), 2.03(1) and 2.01(1) ?, respectively.

Full text of DOI:10.1016/j.inoche.2004.02.001

Inorganic Chemistry Communications 7 (2004) 502–505
www.elsevier.com/locate/inoche
First structurally characterized complex of an acyclic tellurated Schiff
base [4-MeOC6H4TeCH2CH2N@C(CH3)C6H4-2-OH (L1H)] having
metal–tellurium bond; synthesis and crystal structure of [PdCl(L1)]
a
a,
b
Raghavendra Kumar P. , Ajai K. Singh *, J.E. Drake ,
c
M.B. Hursthouse , M.E. Light
c
a
Department of Chemistry, Indian Institute of Technology, Hauz khas, New Delhi 110016, India
Department of Chemistry and Biochemistry, University of Windsor, Windsor, Ont., Canada N9B 3P4
b
c
Department of Chemistry, University of Southampton, Southampton SO17 1BJ, UK
Received 18 January 2004; accepted 3 February 2004
Published online: 4 March 2004
Abstract
Acyclic tellurated Schiff base [4-MeOC6H4TeCH2CH2N@C(CH3)C6H4-2-OH (L1H)] has been synthesized by reacting 2-(4-
methoxyphenyltelluro)ethylamine with o-hydroxyacetophenone. The L1H on reaction with Na2PdCl4 forms a complex [PdCl(L1)] in
which the tellurated Schiff base coordinates in a tridentate mode. The proton and carbon-13 NMR spectra of L1H and the complex
are characteristic. The single crystal structure of the complex is solved. The Pd–Te, Pd–Cl, Pd–O and Pd–N bond distances are
ꢀ
2.504(1), 2.290(4), 2.03(1) and 2.01(1) A, respectively.
Ó 2004 Elsevier B.V. All rights reserved.
Keywords: Palladium; Acyclic tellurated Schiff base; Complex; Synthesis; Single crystal structure
The interest in neutral tellurium ligands [1–4] has
considerably grown during the last decade. The main
reasons for it are the increasing evidence of enhanced
ligating properties of telluroether ligands compared to
thioethers, the availability of standardized synthetic
routes to the ligands, the possibility of using metal
complexes of Te-ligands as precursor for II–VI semi-
conductors, and the improved availability of FT-NMR
for studying behaviour of metal–tellurium bond in so-
lution. Polydentate acyclic tellurated Schiff bases are
also reported [3] but none of their complexes, in which
there is metal–tellurium bond is structurally character-
ized so far. We have synthesized a potentially (Te, N, O)
type Schiff base ligand [4-MeOC6H4TeCH2CH2N@
C(CH3)C6H4-2-OH (L1H)] and found that its Te donor
site participates in coordination with Pd(II). The com-
plex, [PdCl(L1)] is structurally characterized and is the
first example. The results of these investigations are re-
ported in the present communication.
OCH3
1
H3C
N
Te
2
3
4
OH
9
5
6
8
7
L1H
The ligand L1H was synthesized by reactions given in
Scheme 1. The synthesis of 4-MeOC6H4TeCH2CH2NH2
was based on the reported method [5]. The tellurated
Schiff base L1H is stable and can be stored under am-
bient conditions up to six months. It has good solubility
in CHCl3, CH2Cl2, CH3CN, EtOH and acetone but in
hexane it is partially soluble only. The molecular weight
* Corresponding author. Tel.: +11-26591379; fax: +91-11-26862037/
+11-6581037.
E-mail addresses: aksingh@chemistry.iitd.ac.in, ajai57@hotmail.
com (A.K. Singh).
1387-7003/$ - see front matter Ó 2004 Elsevier B.V. All rights reserved.
doi:10.1016/j.inoche.2004.02.001

503
R. Kumar P. et al. / Inorganic Chemistry Communications 7 (2004) 502–505
,
N2
atm
NaBH4
EtOH
.
+ ClCH2CH2NH2 HCl
4
-MeOC6H4Te
CH3
]
[
-MeOC H Te
4
6
4
2
Reflux
,
EtOH
O
L1H
+
4-MeOC6H4TeCH2CH2NH2
(Yield ~85 %)
HO
Acetone-H2O
r..t.
[Na2PdCl4] + L1H
[PdCl(L1)] (1)
(Yield ~ 72 %)
Scheme 1.
Table 1
Crystal data and structure refinement for [PdCl(L1)]
Empirical formula
Formula weight
Temperature, K
C
17H18O2 N Cl Pd Te
Index ranges
ꢁ24 6 h 6 28; ꢁ19 6 k 6 20; ꢁ11 6 l 6 12
7327
537.77
120(2)
0.71073
Reflections collected
Independent reflections
Maximum and minimum
transmission
3132 [Rint ¼ 0:0962]
0.7035 and 0.6694
ꢀ
Wavelength, A
Crystal system
Space group
Orthorhombic
Aba2
Refinement method
Full-matrix least-squares on F 2
3132/1/201
0.998
Data/restraints/parameters
Goodness-of-fit on F 2
Final R indices [F 2 > 4rðF 2Þ]
R indices (all data)
ꢀ
a, A
21.912(3)
16.019(3)
9.782(1)
3433.6(9)
8
ꢀ
b, A
R1 ¼ 0:0590, wR2 ¼ 0:1306
R1 ¼ 0:1118, wR2 ¼ 0:1564
)0.13(6)
0.00069(13)
1.319 and )1.262
ꢀ
c, A
ꢀ
Volume, A
3
Absolute structure parameter
Extinction coefficient
Largest dꢁiff3 erential peak and
Z
Density (calculated), g/cm3
2.081
ꢀ
hole, e A
Absorption coefficient, mmꢁ1
F(0 0 0)
2.910
2064
Crystal size, mm3
0.15 ꢂ 0.15 ꢂ 0.13
3.07–27.46
h range for data collection, °
determined in chloroform (concentration ꢀ5 mM) with
a Knauer vapour pressure osmometer (model A0280)
has been found to be consistent with monomeric nature
of L1H. The IR spectra of L1H were found characteristic
showing ˜C@N stretching vibrations at 1612 cmꢁ1. The
Te–C(alkyl) vibrations are observed in the IR spectra at
[9] and was refined using the WinGX version [10] of
SHELX-97 [11]. All of the non-hydrogen atoms were
treated anisotropically. Hydrogen atoms were included
Table 2
1
ꢀ
Selected bond lengths [A] and angles [°] for [PdCl(L )]
513–518 cmꢁ1, whereas Te–C(aryl) appear at 292 cmꢁ1
.
The L1H and complex [PdCl(L1)] show characteristic 1H
and 13C{1H}NMR spectra [6,7]. The single crystals of
[PdCl(L1)] were grown from a mixture of chloroform,
methanol and hexane. Its colourless, block crystal was
mounted on a glass fibre. X-ray diffraction data were
collected on an Enraf Nonius Kappa CCD area detector
diffractometer, with / and x scans chosen to give a
complete asymmetric unit. Cell refinement [8] gave cell
constants corresponding to an orthorhombic cell whose
dimensions are given in Table 1 along with other ex-
perimental parameters. An absorption correction was
applied [8]. The structure was solved by direct methods
Pd(1)–Te(1)
Pd(1)–O(1)
2.504(1)
2.03(1)
2.15(1)
1.34(2)
1.47(2)
177.9(3)
92.5(3)
89.2(5)
123(1)
Pd(1)–Cl(1)
Pd(1)–N(1)
Te(1)–C(1)
N(1)–C(1)
2.290(4)
2.01(1)
2.13(1)
1.32(2)
Te(1)–C(10)
O(1)–C(4)
N(1)–C(9)
Te(1)–Pd(1)–O(1)
Cl(1)–Pd(1)–O(1)
O(1)–Pd(1)–N(1)
Pd(1)–N(1)–C(1)
Pd(1)–O(1)–C(4)
Pd(1)–Te(1)–C(10)
N(1)–C(1)–C(3)
C(1)–N(1)–C(9)
Te(1)–C(11)–C(16)
Cl(1)–Pd(1)–N(1)
Te(1)–Pd(1)–Cl(1)
Te(1)–Pd(1)–N(1)
Pd(1)–N(1)–C(9)
Pd(1)–Te(1)–C(11)
N(1)–C(1)–C(2)
177.8(4)
89.4(1)
88.9(4)
114(1)
100.1(4)
120(1)
120(1)
119(1)
93.7(6)
112.2(9)
89.2(4)
120(1)
C(2)–C(1)–C(3)
Te(1)–C(11)–C(12)
C(10)–Te(1)–C(11)
123(1)
122(1)

R. Kumar P. et al. / Inorganic Chemistry Communications 7 (2004) 502–505
504
Fig. 1. ORTEP plot of the molecule [PdCl(L1)]. The atoms are drawn with 50% probability ellipsoids.
in idealized positions. Their isotropic thermal parame-
References
ters were taken as 1.2 times to that of the carbon atom
to which they were attached. Selected bond distances
and bond angles are given in Table 2 and the molecule is
displayed in the ORTEP diagram in Fig. 1.
[1] (a) A.K. Singh, V. Srivastava, J. Coord. Chem. 27 (1992) 237;
(b) A.K. Singh, S. Sharma, Coord. Chem. Rev. 209 (2000) 49.
[2] A.K. Singh, Proc. Indian Acad. Sci. (Chem. Sci.) 114 (2002)
357.
Additional material available from the Cambridge
Crystallographic Data Centre comprises the final
atomic coordinates and thermal parameters for all
atoms and a complete listing of bond distances and
angles. The geometry around palladium is square
planar. The Pd–Te bond length in the present complex
[3] (a) E.G. Hope, W. Levason, Coord. Chem. Rev. 12 (1993) 109;
(b) W. Levason, D. Orchard, G. Reid, Coord. Chem. Rev. 225
(2002) 159;
(c) J.A. Barton, A.R.J. Genge, N.J. Hill, W. Levason, S.D.
Orchard, B. Patel, G. Reid, A.J. Ward, Heteroatom Chem. 13
(2002) 550.
[4] (a) J. Arnold, Prog. Inorg. Chem. 43 (1995) 353;
(b) P. Mathur, Adv. Organomet. Chem. 41 (1997) 243.
[5] A.K. Singh, V. Srivastava, Phosphorus Sulfur Silicon 47 (1990)
471.
ꢀ
2.504(1) A is shorter in comparison to earlier reports,
2.517(1) [12], 2.5873(2) [13] and 2.5865(2) to 2.6052(2)
ꢀ
A [14]. This appears due to combined effect of tri-
[6] L1H: Molecular weight. Calc.: 396.6. Found: 399.0. m.p. 82–83
dentate nature of hybrid organotellurium ligand and
the absence of strong trans influence in the present
complex molecule. The Pd–Cl bond distance 2.290(4)
°C. Anal.: Found: C, 51.26; H, 4.81; N, 3.16; Te, 31.86%; Calc. for
C
17H19NO2Te: C, 51.44; H, 4.82; N, 3.53; Te, 32.15%. NMR: 1H
(CDCl3, 25 °C): d (vs. TMS): 2.27 (s, 3H, CH3), 3.13 (t, 2H, H2),
3.81 (s, 3H, OCH3), 3.92 (t, 2H, H1), 6.76–6.82 (m, 3H, ArH m to
Te and H7), 6.945 (d, J ¼ 8:4 Hz, 1H, H9), 7.30–7.32, (m, 1H, H8),
7.505 (d, J ¼ 8:1 Hz, 1H, H6), 7.745 (d, J ¼ 8:4 Hz, 2H, ArH o to
Te), 16.00 (bs, 1H, OH); 13C{1H} (CDCl3, 25 °C): d (vs. TMS):
8.32 (CH3), 14.54 (C2), 50.87 (C1), 55.11 (OCH3), 99.67 (ArC–Te),
115.21 (ArC m to Te), 117.11 (C6), 118.63 (C8), 119.10 (C4), 127.97
(C9), 132.40 (C7), 141.34 (ArC o to Te), 159.90 (ArC–OCH3),
163.53 (C5), 171.38 (C3).
ꢀ
ꢀ
A is within the range of values 2.287(3)–2.352(3) A
reported for Pd(II) complexes of hybrid organotellu-
rium ligands [12–14]. The Pd–O bond lengths in the
ꢀ
present complex 2.03(1) A are consistent with the
ꢀ
range of values from 1.999(6) to 2.105(3) A reported
for five and six membered chelate rings containing Pd–
ꢀ
O bond [15,16]. The Pd–N bond distance 2.01(1) A is
close to the sum of the covalent radii of palladium and
[7] PdCl(L1)]: m.p. 162 °C. Anal.: Found: C, 37.48; H, 3.47; N, 2.43;
Te, 23.65%. Calc. for C17H18ClNO2PdTe: C, 37.97; H, 3.37; N,
2.60; Te, 23.80%. NMR; 1H (CDCl3, 25 °C): d (vs. TMS): 2.39 (s,
3H, CH3), 3.49 (t, 2H, H2), 3.82 (s, 3H, OCH3), 4.17 (t, 2H, H1),
6.61–6.66 (m, 3H, ArH m to Te and H7), 6.915 (d, J ¼ 8:7 Hz, 1H,
H9), 7.12–7.14 (m, 1H, H8), 7.335 (d, J ¼ 9:0 Hz, 1H, H6), 8.065
(d, J ¼ 9:0 Hz, 2H, ArH o to Te); 13C{1H} (CDCl3, 25 °C): d (vs.
TMS): 13.38 (CH3), 19.29 (C2), 62.76 (C1), 55.01 (OCH3), 102
(ArC–Te), 115.38 (ArC m to Te), 115.71 (C6), 120.86 (C8), 125.01
(C4), 127.68 (C9), 130.86 (C7), 138.58 (ArC o to Te), 159.90 (ArC–
OCH3), 163.53 (C5), 171.38 (C3). IR (KBr; cmꢁ1): m(Pd–Cl), 306;
m(Pd–N), 486.
ꢀ
nitrogen (ca. 2.02 A) suggesting strong coordination
through nitrogen. The bond angles at Te and N are
consistent with their nearly trigonal pyramidal
(89.2(4)–100.1(4)°) and trigonal planar geometry
(114(1)–123(1)°), respectively.
Acknowledgements
[8] DENZO data collection and processing software Z. Otwinowski,
W. Minor, Methods in enzymology, in: C.W. Carter Jr., R.M.
Sweet (Eds.), Macromolecular Crystallography, Part A, vol. 276,
Academic Press, 1997, pp. 307–326.
AKS and RKP thank the Council of Scientific and
Industrial Research (India) for financial support (Pro-
ject No. 01(1849)/03/EMR-II). M.B.H. thanks the UK
Engineering and Physical Sciences Council for support
of the X-ray facilities at Southampton. J.E.D. thanks
the University of Windsor for financial support.
[9] G.M. Sheldrick, Acta Cryst. A 46 (1990) 467.
[10] L.J. Farrugia, J. Appl. Cryst. 32 (1999) 837.
[11] G.M. Sheldrick, SHELXL 97, University of Gottingen, Germany.
[12] A. Khalid, A.K. Singh, Polyhedron 16 (1997) 33.

505
R. Kumar P. et al. / Inorganic Chemistry Communications 7 (2004) 502–505
[13] A.K. Singh, J. Sooriyakumar, J.E. Drake, M.B. Hursthouse,
M.E. Light, J. Organomet. Chem. 613 (2000) 244.
[15] D.R. Billodeaux, F.R. Fronczek, A. Yoneda, G.R. Newkome,
Acta Cryst. C: Cryst. Struct. Commun. C54 (1998) 1439.
[16] C.J. Pastor, Acta Cryst. E: Struct. Rep. Online E57 (12) (2001)
m595.
[14] A.K. Singh, J. Sooriyakumar, S. Husebye, K.W. Tornroos,
J. Organomet. Chem. 612 (2000) 46.