Thallium(I) salicylate and phthalate: Syntheses and structural characterization

Article abstract of DOI:10.1515/znb-2006-0510

Two new 2D polymers, thallium(I) hydrogensalicylate (1) and hydrogenphthalate (2), have been synthesized and characterized by elemental analysis, IR, ¹H NMR and ¹³C NMR spectroscopy. The single-crystal X-ray data show the coordination number of the Tl^I ions of compounds 1 and 2 to be four and six with the environment TlO ₄ and TlO₆, respectively. The arrangement of the O atoms suggests a gap in the coordination geometry around the thallium atoms in both compounds, due to a stereo-chemically 'active' electron lone pair of Tl ^I. There is another interaction between the thallium atom and the carbon atoms of an aromatic ring in compound 1, giving a total hapticity of ten with the environment C₆O₄Tl.

Full text of DOI:10.1515/znb-2006-0510

Thallium(I) Salicylate and Phthalate: Syntheses and Structural
Characterization
Azadeh Askarinejada, Ali Asgar Torabib, and Ali Morsalia
a Department of Chemistry, School of Science, Tarbiat Modarres University,
P. O. Box 14155-4838, Tehran, Iran
b Department of Chemistry, Zanjan University, P. O. Box 49195-313, Zanjan, Iran
Reprint requests to Dr. Ali Morsali. Fax: +98 21 8006544. E-mail: morsali a@yahoo.com
Z. Naturforsch. 61b, 565 – 569 (2006); received October 25, 2005
Two new 2D polymers, thallium(I) hydrogensalicylate (1) and hydrogenphthalate (2), have been
synthesized and characterized by elemental analysis, IR, 1H NMR and 13C NMR spectroscopy. The
single-crystal X-ray data show the coordination number of the TlI ions of compounds 1 and 2 to be
four and six with the environment TlO4 and TlO6, respectively. The arrangement of the O atoms
suggests a gap in the coordination geometry around the thallium atoms in both compounds, due to a
stereo-chemically ‘active’ electron lone pair of TlI. There is another interaction between the thallium
atom and the carbon atoms of an aromatic ring in compound 1, giving a total hapticity of ten with the
environment C6O4Tl.
Key words: Thallium, Crystal Structure, Lone Pair, Phthalate, Salicylate
Introduction
gives the crystalline materials {Tl[(H)salicylate)]}n
(1)/{Tl[(H)phthalate)]}n (2). The IR spectra of these
compounds show absorption bands resulting from the
skeletal vibrations of aromatic rings in the 1400–
1523 cm−1 range. The relatively weak bands at around
3040 and 3050 cm−1 are assigned to the ν(CH) mode
of the salicylate and phthalate rings in 1 and 2, respec-
tively. The broad absorption band for ν(H-O) appears
at ca. 3420 and 3430 cm−1, respectively, attributable
to ν(O-H···X) hydrogen bonds. The structures of com-
pounds 1 and 2 were confirmed by X-ray crystallo-
graphy.
Thallium reagents, despite their inherent toxicity
and cost, have played an important role in the develop-
ment of modern inorganic and organometallic chem-
istry [1 – 10]. Thallium, when compared with the re-
mainder of the group 13 elements, shows a preference
for the oxidation state +1. This has been attributed to
the effect of the inert pair of electrons introduced by
Sidgwick and generally used in introductory textbooks
to explain the tendency of the heavier main-group ele-
ments to adopt oxidation numbers that are 2 less than
the respective group number. This phenomenon origi-
nates from a combination of shell structure effects and
relativity. Owing to the relativistic downshift in energy
of the 6s orbital, Tl does indeed favor the oxidation
state +1 over +3. Moreover, Tl might be regarded as a
relativistic alkali metal because Tl chemistry parallels
that of the alkali metals in many ways [7].
Determination of the structure of the 1 and 2 by
X-ray diffraction (Table 1, Figs 1 and 2) has shown the
compounds to be two-dimensional polymers (Figs 3
and 4). The thallium atoms can be considered to be
four- and six-coordinate, respectively. The separations
˚
between the thallium atoms are 4.33(2) and 4.037(3) A
in 1 and 2, respectively, longer than the sum of van
In recent works we have reported the crystal struc-
tures of a TlI phthalate [2 – 3], and in this paper we
extend this subject to include hydrogensalicylate and –
phthalate which are found to be two-dimensional poly-
mers with a stereo-chemical activity of the Tl(I) va-
lence shell electron lone pair.
I
˚
der Waals radii of ca. 3.92 A [10] of two Tl . Hence,
a thallophilic Tl···Tl interaction in these compounds
can not be considered. The (H)salicylate− anion acts
as a tetradentate ligand, connecting four TlI ions.
The carboxylate group of this ligand acts only as a
bridging unit (Fig. 1). The carboxylate groups of the
(H)phthalate− ligand act as both bidentate chelating,
Results and Discussion
The reaction between thallium(I) nitrate and mix- and bridging units. Two oxygen atoms of one -COO
tures of sodium salicylate/phthalate in methanol group coordinate to a thallium(I) ion, also these oxy-
c
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A. Askarinejad et al. · Thallium(I) Salicylate and Phthalate
Table 1. Crystal data and
structure refinement for
[Tl((H)salicylate)]n (1) and
{Tl[(H)phthalate)]}n (2).
Identification code
Empirical formula
Formula weight
1
2
C7H503Tl
341.48
293(2)
0.71073
orthorhombic
Pbca
C8 H5 04Tl
369.49
120(2)
0.71073
orthorhombic
Pca21
Temperature [K]
˚
Wavelength [A]
Crystal system
Space group
Unit cell dimensions [A]
˚
a
b
c
8.8021(18)
8.2930(19)
19.773(4)
1443.4(5)
8
3.14
22.3
1216
0.30×0.20×0.20
2.06 to 30.06
0 ≤ h ≤ 12
0 ≤ k ≤ 11
−27 ≤ l ≤ 27
3891
9.9915(8)
12.8729(11)
6.5646(6)
844.34(13)
4
2.91
19.1
664
0.17×0.17×0.25
2.58 to 27.49
−7 ≤ h ≤ 12
−6 ≤ k ≤ 16
−8 ≤ l ≤ 8
6439
3
˚
Volume [A ]
Z
Density (calculated) [g/cm3]
Absorption coefficient [mm−1
F(000)
]
Crystal size [mm3]
◦
θ Range for data collection [ ]
Index ranges
Reflections collected
Independent reflections
Completeness to theta [%]
Max. and min. transmission
Refinement method
2072 [R(int) = 0.0454]
98.0
1755 [R(int) = 0.0267]
96.8
0.022 and 0.014
0.034 and 0.004
Full-matrix least-squares on F2 Full-matrix least-squares on F2
Data / restraints / parameters
Goodness-of-fit on F2
Final R Indicate [I > 2σ(I)]
R indices (all data)
2072/0/100
0.938
R1 = 0.0367, wR2 = 0.0744
R1 = 0.0679, wR2 = 0.0788
1.85 and −1.14
1755/1/121
1.089
R1 = 0.0376, wR2 = 0.0860
R1 = 0.0421, wR2 = 0.0876
1.97 and −2.00
−0.00(2)
−3
˚
Largest diff. Peak and hole [e·A
]
Flack’s parameter
Fig. 2. ORTEP
diagram of the
asymmetric unit of
{Tl[(H)phthalate)]}n
(2).
gen atoms bridge to four other thallium atoms. Inter-
estingly, one of the oxygen atoms in this compound
is linked to three different thallium atoms, a very novel
and interesting behavior of carboxylate groups (Fig. 4).
The oxygen atom of the –OH group is coordinated to
thallium atoms in 1 whereas this group in the 2 is not
coordinated to thallium atoms.
The arrangement of the oxygen atoms of the
(H)salicylate− and (H)phthalate− ligands suggest a
gap in the coordination geometry around the metal ions
Fig. 1. ORTEP diagram of the asymmetric unit of
[Tl((H)salicylate)]n (1), showing intramolecular hydrogen
bonding.
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A. Askarinejad et al. · Thallium(I) Salicylate and Phthalate
567
Fig. 3. 2D frame of the [Tl((H)salicylate)]n (1).
Fig. 5. Environment of the Tl-atom in [Tl((H)salicylate)]n
(1), showing of Tl···C interactions on extending the bonding
limit.
Fig. 4. 2D frame of the {Tl[(H)phthalate)]}n (2).
in the both compounds, occupied possibly by a stereo-
active lone pair of electrons on the thallium atoms. The
observed shortening of the Tl-O bonds on the side of
Tl ion opposite to the putative lone pair (Tl1-O2i =
˚
2.54(6) and Tl1-O4 = 2.743(8) A compared with Tl1-
ii
˚
O3 = 2.93(5) and Tl1-O4 = 3.035(9) A adjacent to
the lone pair in 1 and 2, respectively) (Figs 5 and 6)
supports the presence of this feature [12].
With a low formal coordination number of 4 for
the Tl atom in 1, one tends to look for secondary
interactions that could possibly relieve this coordina-
Fig. 6. Environment of the Tl-atoms in {Tl[(H)phthalate)]}n
(2).
tive unsaturation. To find other potential donor cen- 3.90(4), C3iii ···Tl = 3.81(4), C4iii ···Tl = 3.72(4),
iii
iii
˚
ters, it is necessary to extend the bonding limit. A C5 ···Tl = 3.69(6) and C6 ···Tl = 3.79(4) A
search was made generally for Tl···C approaches (Fig. 5). Hence, its coordination sphere in 1 is com-
in 1 and 2, and it appears that the Tl atoms of pleted to obtain an irregular ten coordination. The re-
1 may also be involved in an η 6 interaction with ported Tl···C separations range is 3.20 – 4.00 A in re-
˚
the phenyl groups of salicylate anion. The TlI atom cently reported species [5, 13]. Thus, hexahapto aro-
in 1 has contacts to six carbon atoms of a phenyl matic coordination of Tl(I) appears to be yet another
ring, with distances C1iii ···Tl = 3.91(5), C2iii ···Tl = factor which can make varying contributions to the sta-
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A. Askarinejad et al. · Thallium(I) Salicylate and Phthalate
◦
˚
Table 2. Selected bond lengths [A] and angles [ ] for
[Tl((H)salicylate)]n (1).
bility of complexes of this metal ion. A recent report
of polyhapto-aromatic interactions in lead(II) coordi-
nation has suggested that the active lone pair of Pb(II)
may be involved in donor bonding [14]. A compari-
son to the usual results may indicate that the unusually
high coordination number in 1 reflects the capacity of
Tl(I) to act like Pb(II) as both a Lewis acid and a Lewis
base.
Tl1-O2i
Tl1-O1
2.54(6)
2.81(6)
4.33(2)
3.91(5)
3.81(4)
3.69(6)
Tl1-O1ii
Tl1-O3
2.62(6)
2.92(5)
Tl1i-Tl1iii
C1iii-Tl1
C3iii-Tl1
C5iii-Tl1
C2iii-Tl1
C4iii-Tl1
C6iii-Tl1
O2i -Tl1-O1
O2i-Tl1-O3iii
O1-Tl1-O3iii
3.90(4)
3.72(4)
3.79(4)
Tl1-O2i-Tl1-O1ii
79.5(2)
74.2(2)
81.7(2)
74.7(2)
84.1(2)
150.3(2)
O1ii-Tl1-O1
O1ii-Tl1-O3iii
Experimental Section
Symmetry codes: : x + 1/2, −y + 1/2, −z + 1, ii: −x + 1, −y,
i
Sample characterization
−z+1, iii: x+1, y, z.
IR spectra were recorded as nujol mulls using Perkin-
Elmer 597 and Nicolet 510P spectrophotometers. Microanal-
yses were carried out using a Heraeus CHN-O-Rapid ana-
lyzer. Melting points were measured on an Electrothermal
9100 apparatus and are uncorrected. The 1H and 13C NMR
solution NMR spectra were recorded on a Bruker DRX-500
AVANCE spectrometer at 500 and 125 MHz, respectively.
◦
˚
Table 3. Selected bond lengths [A] and angles [ ] for
{Tl[(H)phthalate)]}n (2).
Tl1-O4
Tl1-O3i
Tl1-O3iii
2.74(8)
2.88(8)
2.98(8)
Tl1-O4ii
Tl1-O1i
Tl1-O4i
O4-Tl1-O3i
O4-Tl1-O1i
O3)-Tl1-O1i
O4ii-Tl1-O3iii
O1i-Tl1-O3iii
O4ii-Tl1-O4i
O1i-Tl1-O4i
2.83(9)
2.96(8)
3.03(9)
O4-Tl1-O4ii
O4ii-Tl1-O3i
O4ii-Tl1-O1i
O4-Tl1-O3iii
O3i-Tl1-O3iii
O4-Tl(-O4i
91.3(2)
85.8(2)
123.6(2)
81.3(2)
64.0(2)
136.0(2)
87.9(2)
113.5(3)
66.6(2)
136.1(2)
96.2(3)
123.60(19)
147.7(3)
44.1(2)
Preparation of {[Tl(H)salicylate)]}n (1)
The compound was prepared by dissolving 0.266 g
(1 mmol) of thallium(I) nitrate in distilled water and meth-
anol and adding a mixture of phthalic acid (0.158 g, 1 mmol)
and sodium hydroxide (0.04 g, 1 mmol) in methanol. The
resulting mixture was stirred for 1 h. The solution was al-
lowed to stand at room temperature for several days. After
evap◦oration of the solvent crystals were obtained (m.p. >
300 C). Yield: 0.170 g, 50%. C7H503Tl: C 24.59; H 1.45;
Tl 59.82; found: C 24.80; H 1.60; Tl 59.10. – IR (cm−1) se-
lected bonds: ν = 662(m), 754(s), 801(m), 850(m), 1023(w),
1134(s), 1292(vs), 1318(vs), 1382(vs), 1473(vs), 1580(vs),
2645(w), 3040(w), and 3420(m). – 1H NMR ([D6]-DMSO):
δ = 7.6 (t, 2H), 8.1(t, 2H), and 12.7(b, 1H) ppm. –
O3i-Tl1-O4i
O3iii-Tl1-O4i
80.5(2)
Symmetry codes: : x − 1/2, −y + 1, z, ii: −x + 1/2, y, z + 1/2,
i
iii: −x+1/2, y,z−1/2.
8.1(t, 2H), and 12.5(b, 1H) ppm. – 13C{ H} NMR ([D6]-
1
DMSO): δ = 130.2, 132.3, 135.0 and 168.1 ppm.
X-ray crystallography
X-ray measurements were made at 293(2) K and 120(2) K
using a Siemens R3m/V diffractometer for compounds 1
and 2, respectively. Accurate unit cell parameters and the
orientation matrix for data collection were obtained from
least-squares refinement. The structures have been solved by
direct methods and refined by full-matrix least-squares on
F2. The positions of hydrogen atoms were calculated at ide-
alized geometrical positions and included in the structure-
factor calculation as fixed-atom contributions. The absolate
structure of 2 was determined by refinement of Flack’s pa-
rameter x = −0.00(2) [15].
1
13C{ H} NMR ([D6]-DMSO): δ = 116.4, 117.1, 121.1,
130.4, 132.4, 162.4, 173.2 ppm.
Preparation of {Tl[(H)phthalate)]}n (2)
The compound was prepared by dissolving 0.266 g
(1 mmol) of thallium(I) nitrate in distilled water and
methanol and adding a mixture of phthalic acid (0.186 g,
1 mmol) and sodium hydroxide (0.04 g, 1 mmol) in meth-
anol. The resulting solution was stirred and then allowed
to stand for several days at room temperature. Slow evap-
oration of the solvent at room temperature yielded crys-
tals suitable for X-ray analysis. The cr◦ystals were washed
with acetone and air dried (m. p.= 272 C). Yield: 0.166 g,
Crystal data and refinement parameters are given in Ta-
ble 1. Selected bond lengths and angles are given in Tables 2
and 3.
Supplementary material
Complete bond lengths and angles, co-ordinates and dis-
45%. C8H504Tl: calcd: C 25.98; H 1.35; Tl 55.11; found: placement parameters have been deposited at Cambridge
C 25.82; H 1.50; Tl 54.10. – IR (cm−1) selected bonds: Crystallography Data Centre. Supplementary data are avail-
ν = 667(m), 751(s), 799(s), 1071(m), 1141(s), 1270(vs), able from the CCDC, 12 Union Road, Cambridge CB2 1EZ,
1300(vs), 1470(vs), 1520(vs), 1650(m0, 2885(w), 3050(w), UK on request, quoting the deposition number 283537 for 1
and 3430(m). – 1H NMR ([D6]-DMSO): δ = 7.5 (t, 2H), and 270820 for 2.
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A. Askarinejad et al. · Thallium(I) Salicylate and Phthalate
569
Acknowledgements
Support of this investigation by Tarbiat Modarres and
Zanjan Universities is gratefully acknowledged.
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