Complexity of coordinative bonding in thallium(I) anthranilates and salicylates

Article abstract of DOI:10.1021/ja0287783

An inventory of the structural chemistry of thallium(I) shows many unexpected, almost random coordination numbers and coordination geometries that appear erratic and inconsistent. This nonstandard behavior is often ascribed to the specific lone-pair characteristics originating from relativistic effects. To provide data on a set of closely related compounds from which simple general rules of coordinative bonding at TI⁺ can be established, three thallium(I) anthranilates and three thallium(I) salicylates have been prepared from TI₂CO₃ and the corresponding 2-amino- and 2-hydroxy-benzoic acids and crystallized from aqueous solutions. All six compounds, the simple anthranilate (1) and salicylate (4) and the 3- and 4- methyl-substituted homologues (2, 3 and 5, 6) show different structures with large variations in the coordination motif. The coordination by oxygen in a geometry which covers less than a coordination hemisphere is the only common feature, complemented (only in 1) by a nitrogen coordination and by η⁶-coordination of one (in 1, 2, 3, 6) or two phenyl rings (in 4). TI-TI contacts for which thallophilic bonding between closed shell metal atoms could be invoked, are generally very long (close to 4.0 A) or even well beyond the limit of standard van der Waals contacts. Hydrogen bonding is only obvious for the internal contacts of the amino- or hydroxybenzoate ligands and does not contribute significantly to the assembly of the supramolecular structure which is dominated by oxygen bridges between thallium atoms. With the exception of 5, the formula units TI[O₂C(2-R)(3-R′)(4-R″)C₆H₂] are generally aggregated into dimers of various configurations depending on the relative orientation of the edge-sharing four-membered rings, and these dimers are further linked into strings or columns establishing N-TI or TI-O contacts and arene coordination. The drastic changes induced in the structures upon only small variations such as methyl substitution in 3- or 4-position of the ligand suggest that thallium(I) coordination is generally restricted to one hemisphere of nearest neighbors, but is extremely flexible in this realm. The open hemisphere may be partially capped by arene coordination (which is weak at a distance of ca. 3.1 A to the centroid of the ring) or feature very weak thallophilic contacts.

Full text of DOI:10.1021/ja0287783

Published on Web 02/22/2003
Complexity of Coordinative Bonding in Thallium(I)
Anthranilates and Salicylates
Frank Wiesbrock and Hubert Schmidbaur*
Contribution from the Anorganisch-Chemisches Institut der Technischen UniVersita¨t Mu¨nchen,
Lichtenbergstrasse 4, D-85747 Garching, Germany
Received October 2, 2002 ; E-mail: H.Schmidbaur@lrz.tum.de.
Abstract: An inventory of the structural chemistry of thallium(I) shows many unexpected, almost random
coordination numbers and coordination geometries that appear erratic and inconsistent. This nonstandard
behavior is often ascribed to the specific lone-pair characteristics originating from relativistic effects. To
provide data on a set of closely related compounds from which simple general rules of coordinative bonding
at Tl+ can be established, three thallium(I) anthranilates and three thallium(I) salicylates have been prepared
from Tl2CO3 and the corresponding 2-amino- and 2-hydroxy-benzoic acids and crystallized from aqueous
solutions. All six compounds, the simple anthranilate (1) and salicylate (4) and the 3- and 4-methyl-substituted
homologues (2, 3 and 5, 6) show different structures with large variations in the coordination motif. The
coordination by oxygen in a geometry which covers less than a coordination hemisphere is the only common
feature, complemented (only in 1) by a nitrogen coordination and by η6-coordination of one (in 1, 2, 3, 6)
or two phenyl rings (in 4). Tl-Tl contacts for which “thallophilic” bonding between closed shell metal atoms
could be invoked, are generally very long (close to 4.0 Å) or even well beyond the limit of standard van der
Waals contacts. Hydrogen bonding is only obvious for the internal contacts of the amino- or hydroxy-
benzoate ligands and does not contribute significantly to the assembly of the supramolecular structure
which is dominated by oxygen bridges between thallium atoms. With the exception of 5, the formula units
Tl[O2C(2-R)(3-R′)(4-R′′)C6H2] are generally aggregated into dimers of various configurations depending
on the relative orientation of the edge-sharing four-membered rings, and these dimers are further linked
into strings or columns establishing N-Tl or Tl-O contacts and arene coordination. The drastic changes
induced in the structures upon only small variations such as methyl substitution in 3- or 4-position of the
ligand suggest that thallium(I) coordination is generally restricted to one hemisphere of nearest neighbors,
but is extremely flexible in this realm. The open hemisphere may be partially capped by arene coordination
(which is weak at a distance of ca. 3.1 Å to the centroid of the ring) or feature very weak thallophilic contacts.
Introduction
exceedingly low coordination numbers in geometries which
leave a large part of the coordination sphere seemingly unoc-
In modern coordination chemistry the role of most metals as
clustering centers for ligands appears to be predictable. From a
consideration of the size and the electronic configuration in a
certain oxidation state of the acceptor center, and of the relative
size and donor properties of the ligand functions, the coordina-
tion number and the coordination geometry can be extrapolated
for most of the common metal/ligand combinations with quite
high certainty. Although this is generally true, the situation is
surprisingly difficult for main group metals in their low
oxidation states in which they are to be assigned lone pairs of
electrons.
cupied.3 By contrast, potassium and rubidium cations always
have their coordination sphere covered as completely and as
symmetrically as possible, optimizing the Coulomb energy.
Thallium(I) coordination may be generally built on several
quite different types of metal-ligand interactions: Owing to
the relativistically contracted valence shell and the low electrical
charge, the Tl+ cation is intermediate between standard hard
and soft character and has affinity for both hard and soft donor
atoms, like oxygen and sulfur, or chloride and iodide, and so
forth. Therefore, there is a plethora of very stable hydroxide,
alkoxide, and carboxylate, but also sulfide, thiolate, thiocar-
boxylate, or thiocarbamate complexes, with Tl-O and Tl-S
coordination, respectively.1 However, these ligands cover only
a certain part of the environment even if ligands are available
in large excess. Attempts to ascribe this phenomenon solely to
the stereochemically active 6s2 lone pair of electrons have not
A prominent example for pertinent complications is thal-
lium(I) with its bewildering complexity of coordination numbers
and geometries.1 Although one of the larger cations, with
tabulated ionic radii between 1.45 and 1.59 Å (intermediate
between those of potassium and rubidium),2 it often shows
(1) (a) Inorganic Crystal Structure Data Base, Gmelin Institut Fachinforma-
tionzentrum: Karlsruhe, Germany. (b) Gmelin Handbuch der Anorganis-
chen Chemie, 8. Aufl., Band 38, Thallium; Springer-Verlag: Berlin, 1940,
p 386.
(2) (a) Bondi, A. J. Phys. Chem. 1964, 68, 441. (b) Emsley, J. The Elements,
2nd ed.; Clarendon Press: Oxford, 1991.
(3) Janiak, C. Coord. Chem. ReV. 1997, 163, 107.
9
3622
J. AM. CHEM. SOC. 2003, 125, 3622-3630
10.1021/ja0287783 CCC: $25.00 © 2003 American Chemical Society

Thallium(I) Anthranilates and Salicylates
A R T I C L E S
Scheme 1: Coordination Modes of Thallium Cations and Anthranilate Anions in Compounds 1 to 3
been fully convincing in quite a number of cases with
nonstandard coordination geometries.4
In the ligand-bare regions of its coordination sphere, Tl+s
unexpected for a main group metalsalso forms π-complexes
with aromatic hydrocarbons as first demonstrated for the anionic
cyclopentadienyl ligands30,31 in 1957, and in 1985 for neutral
arenes.32,33 In these compounds the cation has a centered η6-
coordination at rather large metal-centroid distances of ca. 3.05
Å. Recently, investigations of the complexation modes of
monovalent thallium ions were extended to the tris- and poly-
(pyrazolyl)borate as well as the tris(indazolyl)borate ligands.34
The crystalline phases of these compounds reveal many varia-
tions in the metal-ligand arrangement and crystal packing: In
addition to the complexation of the thallium ions by the nitrogen
donors and arene moieties, Tl-Tl-interactions and π-π-stacking
are also observed. A series of 3,5-disubstituted pyrazolates
shows analogous complexation modes.35
In the present study, the structural chemistry of thallium(I)
anthranilates and salicylates with a selected substitution pattern
was investigated with the following incentives (Scheme 1):
(1) Anthranilate and salicylate anions offer hard and strongly
basic donor centers in a ligand geometry facilitating chelation
and/or metal bridging for a medium- to large-size cation and
should be prone to fill its coordination sphere exhaustively. (2)
If bare regions are left in the coordination sphere despite the
over-supply of ligand donor functions, then the ligands would
still be capable to cover these regions by arene coordination.
(3) If a given substitution pattern of the ligands will rule out
such η6-arene interactions due to steric hindrance, then the
monomeric or oligomeric units may aggregate via thallophilic
contacts. (4) Both the hydroxy and the amino group in salicylate
or anthranilate anions, respectively, can entertain intra- and/or
intermolecular hydrogen bonding to assist a multidimenional
assembly of the components.
In the resulting bare regions the coordinated [Tl]+ ion often
has very distant contacts (up to 4.0 Å) with [Tl]+ centers of
neighboring complexes, but the significance of this type of
interactionsif there is anyshas recently been the subject of
much debate.5-23 “Thallophilic” Tl-Tl contacts should probably
be considered as particularly weak cases of “metallophilic”
bonding5 between closed-shell atoms as compared for example
to the particularly strong “aurophilic” bonding between Au+
complexes.24-26 Notwithstanding, relativistic and correlation
effects which are known to affect most strongly the energy of
the 6s2 electrons of the heaviest metals in the last period and
thus to determine the energy levels of the frontier orbitals,27
are also held responsible for the unusual properties of mixed-
metal complexes where the two extreme cases, Tl+ and Au+,
are combined, in which short contacts are indicative of strong
closed-shell interactions.5,28,29
(4) Kristiansson, O. Eur. J. Inorg. Chem. 2002, 2355.
(5) Pyykko¨, P. Chem. ReV. 1997, 97, 597.
(6) Schwerdtfeger, P. Inorg. Chem. 1991, 30, 1660.
(7) (a) Parkin, G. AdV. Inorg. Chem. 1995, 42, 291. (b) Ghosh, P.; Rheingold,
A. L.; Parkin, G. Inorg. Chem. 1999, 38, 5464.
(8) (a) Gabuda, S. P.; Kozlova, S. G.; Davidovich, R. L. Chem. Phys. Lett.
1996, 263, 253. (b) Alcock, N. W.; Jenkins, H. D. B. J. Chem. Soc., Dalton
Trans. 1974, 1907.
(9) Schumann, H. Pure Appl. Chem. 1991, 63, 813.
(10) Schumann, H.; Janiak, C.; Pickardt, J.; Bo¨rner, U. Angew. Chem., Int. Ed.
Engl. 1987, 26, 789.
(11) (a) Janiak, C.; Hoffmann, R. J. Am. Chem. Soc. 1990, 112, 59249. (b)
Janiak, C.; Hoffmann, R. Angew. Chem., Int. Ed. Engl. 1989, 28, 1688.
(12) Galka, C. H.; Tro¨sch, D. J. M.; Schubart, M.; Gade, L. H.; Radojevic, S.;
Scowen, I. J.; McPartlin, M. Eur. J. Inorg. Chem. 2000, 2577, and references
therein.
(13) (a) Hellmann, K. W.; Gade, L. H.; Fleischer, R.; Stalke, D. Chem. Commun.
1997, 527. (b) Hellmann, K. W.; Gade, L. H.; Fleischer, R.; Kottke, T.
Chem. Eur. J. 1997, 3, 1801.
(14) Pritzkow, H.; Jennische, P. Acta Chim. Scand. 1975, A29, 60.
(15) Martin, A.; Orpen, A. G. J. Am. Chem. Soc. 1996, 118, 1464.
(16) (a) Fleming, J. S.; Psillakis, E.; Couchman, S. M.; Jeffery, J. S.; McCleverty,
J. A.; Ward, M. D. J. Chem. Soc., Dalton Trans. 1998, 537. (b) Jones, P.
L.; Mann, K. L. V.; Jerrery, J. C.; McCleverty, J. A.; Ward, M. D.
Polyhedron 1997, 16. (c) Psillakis, E.; Jerrery, J. C.; McCleverty, J. A.;
Ward, M. D. J. Chem. Soc., Dalton Trans. 1991, 47, 2079.
(17) Uhl, W.; Keimling, S. U.; Klinkhammer, K. W.; Schwarz, W. Angew.
Chem., Int. Ed. Engl. 1997, 36, 64.
From the evaluation of the structural chemistry of compounds
with a set of closely related ligands the interplay between the
various bonding contributions may become obvious and help
to understand the complexity of the systems.
Work described in a recent publication by Kristiansson4
followed similar lines and reached similar conclusions for three
thallium benzoates including salicylate Tl+(2-HO-C6H4-
(18) Loos, D.; Baum, E.; Ecker, A.; Schno¨ckel, H.; Downs, A. J. Angew. Chem.,
Int. Ed. Engl. 1997, 36, 860.
(19) Manning, M. J.; Knobler, C. B.; Hawthorne, M. F. Inorg. Chem. 1991, 30,
3589.
(20) Ferguson, G.; Jennings, M. C.; Lalor, F. J.; Shanahan, C. Acta Crystallogr.
1991, C47, 2079.
(29) Balch, A. L.; Fung, E. Y.; Olmstead, M. M. J. Am. Chem. Soc. 1990, 112,
5181.
(30) (a) Fischer, E. O. Angew. Chem. 1957, 69, 207. (b) Meister, H. Angew.
Chem. 1957, 69, 533.
(31) Pyykko¨ P.; Straka, M.; Tamm, T. Phys. Chem. Chem. Phys. 1999, 1, 3441.
(32) (a) Schmidbaur, H.; Bublack, W.; Riede, J.; Mu¨ller, G. Angew. Chem.,
Int. Ed. Engl. 1985, 24, 4. (b) Schmidbaur, H.; Bublack, W.; Huber, B.;
Hofmann, J.; Mu¨ller, G. Chem. Ber. 1989, 122, 102.
(21) Ja¨kle, F.; Polborn, K.; Wagner, M. Chem. Ber. 1996, 129, 603.
(22) Rheingold, A. L.; Liable-Sands, L.; Trofimenko, S. J. Chem. Soc., Chem.
Commun. 1997, 1691.
(23) Neimeyer, M.; Power, P. P. Angew. Chem., Int. Ed. Engl. 1998, 37, 1277.
(24) Schmidbaur, H. Gold Bull. 1990, 23, 11.
(25) Schmidbaur, H. Gold Bull. 2000, 33, 3.
(26) Schmidbaur, H. Chem. Soc. ReV. 1995. 24, 391.
(27) (a) Pyykko¨, P., Desclaux, J. P. Accounts Chem. Res. 1979, 12, 276. (b)
Pitzer, K. S. Accounts Chem. Res. 1979, 12, 271.
(28) (a) Fernandez, E. J.; Jones, P. G.; Laguna, A.; Lopez-de-Luzuriaga, J. M.,
Monge, M.; Perez, J.; Olmos, E. Inorg. Chem. 2002, 41, 1056, and
references therein. (b) Wang, S.; Fackler, J. P., Jr.; King, C.; Wang, J. C.
J. Am. Chem. Soc. 1988, 110, 3308. (c) Fernandez, E. J.; Lopez-de-
Luzuriaga, J. M.; Monge, M.; Olmos, E.; Perez, J. J. Am. Chem. Soc. 2002,
124, 5942.
(33) Beck, J.; Stra¨hle, J. Z. Naturforsch. 1986, 41b, 1381.
(34) (a) Janiak, C.; Temizdemir, S.; Scharmann, T. G. Z. Anorg. Allg. Chem.
1998, 624, 755. (b) Janiak, C.; Braun, L.; Girgsdies, F. J. Chem. Soc.,
Dalton Trans. 1999, 3133. (c) Craven, E.; Mutlu, E.; Lundberg, D.;
Temizdemir, S.; Dechert, S.; Brombacher, H.; Janiak, C. Polyhedron 2002,
21, 553. (d) Janiak, C.; Temizdemir, S.; Dechert, S. Inorg. Chem. Commun.
2000, 3, 271.
(35) Deacon, G. B.; Delbridge, E. E.; Forsyth, C. M.; Skelton, B. W.; White,
A. H. J. Chem. Soc., Dalton Trans. 2000, 745.
9
J. AM. CHEM. SOC. VOL. 125, NO. 12, 2003 3623

A R T I C L E S
Wiesbrock and Schmidbaur
Scheme 2: Benzoic Acids Chosen for the Structural Investigation of Their Thallium(I) Salts. (a) 2-Amino-benzoic Acid (anthranilic acid), (b)
2-Amino-3-methyl-benzoic Acid, (c) 2-Amino-4-methyl-benzoic Acid, (d) 2-Hydroxy-benzoic Acid (salicylic acid), (e)
2-Hydroxy-3-methyl-benzoic Acid, (f) 2-Amino-4-methyl-benzoic Acid
COO)-. This work was preceded by a structural study of
thallium(I) 3-hydroxy-benzoate36 and by a brief investigation
of the solution chemistry of thallium(I) salicylate.37 Our own
study is an extension of recent investigations of the anthranilates
and salicylates of other main group metals, mainly Li, Be, Na,
Mg, K, and Ca, where the absence of lone pairs of electrons
and the insignificance of relativistic effects leads to conventional
modes of coordinative bonding.38-40 It is particularly noteworthy
that in crystals of potassium anthranilate the cations are
completely shielded by oxygen donor atoms and reach coordi-
nation number 7.
Thallium(I) coordination was already probed in this laboratory
Figure 1. Asymmetric unit in the structure of C7H6NO2Tl, 1 (ORTEP
recently with amino acids and related biorelevant ligands,41 and
drawing with 50% probability ellipsoids and atomic numbering).
arene coordination to Tl+ was the subject of earlier investiga-
tions.42
are given in the Experimental section. These data are not
discussed here any further because of their low diagnostic value.
Preparations
Crystal Structures
The thallium(I) salicylates and anthranilates can be prepared
by neutralization of thallium(I) carbonate with the corresponding
acid in boiling water. After reflux for 30 min, clear solutions
are obtained from which the products crystallize on cooling in
almost quantitative yields (82-96%). Single crystals can be
grown by slow recrystallization of pure samples. Elemental
analyses and crystal structure determinations have shown that
all products except one are anhydrous. Equation 1 and Scheme
2 illustrate the set of hydroxy- and amino-benzoates employed
in the preparative and structural studies
In the discussion of the individual structures of the six
thallium anthranilates and salicylates the simple (unsubstituted)
anthranilate will be given a detailed consideration because it
features all important types of thallium coordination. The
substituted anthranilates and the corresponding salicylates will
be treated less comprehensively, only pointing out the significant
differences caused by the introduction of methyl groups at
various positions of the amino- or hydroxy-benzoate ligands.
Thallium(I) 2-amino-benzoate (anthranilate, 1). Crystals
of Tl+[C7H6NO2]- are orthorhombic, space group Pbca, with
Z ) 8 formula units in the unit cell. The asymmetric unit
contains only one formula unit (Figure 1). The carboxylate group
is chelating the metal atom with two significantly different
metal-oxygen contacts of Tl1-O1 2.554(4) and Tl1-O2 2.774-
(5) Å. The four-membered ring is wedge-like with an angle O1-
Tl1-O2 of only 48.97(11)°, and the two oxygen atoms thus
cover only a very small fraction of the coordination sphere of
the metal atom.
These monomers dimerize via donor-acceptor interactions
between O1 and Tl1 of neighboring units to give a four-
membered ring Tl1-O1-Tl1A-O1A as shown in Figure 2.
The angle O1-Tl1-O1A is again small at 74.73(13)° and the
additional contact Tl1-O1A is 2.717(4) Å long. The two
wedges and the four-membered ring are almost coplanar keeping
O1, O1A, and O2 at a given thallium atom in quasi-meridianal
positions.
Tl2CO3 + [HO2C(2-R)(3-R′)(4-R′′)C6H2] H O8
2
Tl[O2C(2-R)(3-R′)(4-R′′)C6H2]‚nH2O
1: R ) NH2, R′ ) H, R′′ ) H, n ) 0
2: R ) NH2 R′ ) CH3, R′′ ) H, n ) 0
3: R ) NH2 R′ ) H, R′′ ) CH3, n ) 0.5
4: R ) OH, R′ ) H, R′′ ) H, n ) 0
5: R ) OH, R′ ) CH3, R′′ ) H, n ) 0
6: R ) OH, R′ ) H, R′′ ) CH3, n ) 0
(1)
The compounds are colorless to pale yellow crystalline materials
which are stable in air and not hygroscopic. Data of elemental
analyses, and lists of characteristic IR-absorption bands (in KBr)
and of prominent peaks in the mass spectra (chemical ionization)
(37) Sahu, K. N.; Bhattacharya, A. K. Curr. Sci. 1967, 36, 70.
(38) Schmidbaur, H. Coord. Chem. ReV. 2001, 215, 223 (Be).
(39) Wiesbrock, F.; Schier, A.; Schmidbaur, H. Z. Naturforsch. 2002, 57b, 251
(Mg).
(40) Wiesbrock, F.; Schmidbaur, H. J. Chem. Soc., Dalton Trans. 2002, 7403.
(41) Mikulcik, P.; Bissinger, P.; Riede, J.; Schmidbaur, H. Z. Naturforsch. 1992,
47b, 952.
(36) Rusakov, S. L.; Chuklanova, E. B.; Gusev, A. I.; Lisyat, T. V.; Kharitonov,
Yu. Ya.; Kolomnikov, I. S. Koord. Khim. 1987, 13, 1613.
(42) Schmidbaur, H. Angew. Chem., Int. Ed. Engl. 1985, 24, 893.
9
3624 J. AM. CHEM. SOC. VOL. 125, NO. 12, 2003

Thallium(I) Anthranilates and Salicylates
A R T I C L E S
Figure 2. Dimerization of the formula unit in the crystalline phase of
compound 1. The resulting four-membered ring Tl(1)2O(1)2 is planar.
Figure 4. Excerpt from the cell plot of the crystalline phase of compound
1, illustrating the long metallophilic contacts between [Tl]+ cations of
adjacent columns of dimers.
thallium atom acquires two nearest thallium neighbors at a
distance of Tl1-Tl1D 3.967(6) Å. This value is in good
agreement with data published for a group of thallium(I)
complexes where association can be assumed in the solid state
via thallophilic interactions.4-23 However weak the thallophilic
contacts may be, the orientation of the metal atoms at the
periphery of the columns suggests that there should be some
contribution to the overall stability of the solid-state structure.
All other Tl-Tl contacts (within a dimer or between dimers of
the same string) are well beyond 4.0 Å.
Hydrogen bonds have not been localized owing to the
uncertainties associated with the positions of the N-bound
hydrogen atoms. From the diagrams it appears that there may
be a significant internal hydrogen bonding in each amino-
benzoate group between O2 as an acceptor and N1-H as a
donor (Figure 1). This hydrogen bond is also suggested by
similar findings for the salicylate (ref 4 and below). There are
no other discernible N-H-O connectivities.
Thallium(I) 2-amino-3-methyl-benzoate (3-methyl-anthra-
nilate, 2). Crystals of Tl+[C8H8NO2]- are monoclinic, space
group C2/c, with Z ) 8 formula units in the unit cell. The
asymmetric unit contains one formula unit. As described for 1
(above) the anion is chelating the metal atom to form a wedge-
like four-membered ring. These fundamental units aggregate
to give dimers the atoms of which are related by a center of
inversion in the middle of the central rhombus (Figure 5). The
dimensions of these quasi-planar dimers are very similar to those
in 1. The geometry also suggests intramolecular hydrogen
bonding between the atoms O2 and N1, although the hydrogen
atoms have not been definitely located.
While the dimers of the anthranilate 1 are joined into strings
via Tl-N and Tl-(arene) coordination (Figure 3), the aggrega-
tion of the 3-methyl-anthranilate 2 is established via a bridging
function of the carboxylate oxygen atoms O2 (Figure 6). In
contrast to the planar rhombus Tl1-O1-Tl1A-O1A found in
the dimer, the four-membered rings Tl1-O2-Tl1A-O2A are
folded into a butterfly shape with a folding angle of 88.67-
(19)°. The backbone of a string of dimers is therefore a sequence
Figure 3. In the crystal structure of compound 1, dimers are shifted relative
to each other in order to establish Tl-(arene) and Tl-N-contacts between
neighboring formula units. Note that an inversion center is situated in the
focal point of the Tl(1)2O(1)2-rhomboid. Selected bond lengths [Å], angles
[°] and symmetry transformations: Tl(1)-O(1) 2.554(4), Tl(1)-O(2) 2.774-
(5), Tl(1)-O(1A)1 2.717(4), Tl(1)-N(1C)2 2.838(5), Tl(1)-XB3(centroid)
3.372(6); O(1)-Tl(1)-O(1A)1 74.73(13), O(1)-Tl(1)-O(2) 48.97(11),
1
O(1A)1-Tl(1)-O(2) 122.51(11), Tl(1)-O(1)-Tl(1A)1 105.27(13); -x,
2
3
-y, -z + 1; x, y - 1, z; -x, -y + 1, -z + 1.
This oxygen donor atom distribution still means very poor
(meridianal) shielding of the metal atom.
Through stacking of the flat dimers each thallium atom builds
contacts with an amino group on one side and an η6 arene ring
on the other (Figure 3). Through these external contacts the
dimers are aggregated into strings of dimers. The distance Tl1-
N1C [2.838(5) Å] is only slightly longer than the Tl-O
distances indicating comparable strengths of this dative bond.
On the opposite side of the flat dimer the metal atom is almost
centrally located above the benzene ring with a Tl1-XB(centroid)
distance of 3.372(6) Å. This distance is about 10% larger than
the reference value reported for a mesitylene ring at Tl+ in
[(C6H3Me3)3Tl2(GaBr4)2]2, which is not unexpected because
mesitylene is a much better donor than amino-benzoate, and
Tl+ must be a much stronger acceptor in its tetrabromogallate
salt as compared to the anthranilate.
These additional contacts complement a coordination hemi-
sphere which still leaves the metal atom wide open in its second
hemisphere: At the rim of the filled hemisphere the angles O2-
Tl1-O1A [122.51(11)°] and N1C-Tl1-XB [148.08(14)°] are
both much less than 180°. The vacancy appears to be finally
compensated by inter-string contacts between thallium atoms
(Figure 4): Through the packing of the strings of dimers each
9
J. AM. CHEM. SOC. VOL. 125, NO. 12, 2003 3625

A R T I C L E S
Wiesbrock and Schmidbaur
(Figure 8). The asymmetric unit contains two independent
formula units. In only one of these two units the metal cation
(Tl1) is chelated by its anthranilate anion, whereas the other
(Tl2) is bridged by the anion to give an eight-membered ring
as the central unit of a tetramer (Figure 9). The peripheral
wedges are attached to the central eight-membered ring via
butterfly-type folded four-membered rings. Both Tl1 and Tl2
are further η6-coordinated to the phenyl rings of neighboring
tetramers with Tl1-X1B (centroid) and Tl2-X2B (centroid)
distances of 3.166(13) and 3.181(15) Å as illustrated in Figure
9. The Tl1-Tl2 and Tl1-Tl2A contacts within a tetramer have
distances just below 4.0 Å, but the corresponding Tl1-O-Tl2
angles are very sharp, suggesting that there is no significant
thallophilic bonding. There are also no Tl-N contacts. Both
Tl1 and Tl2 are thus tri-coordinated by nearest oxygen atoms
in steep trigonal pyramids and η6-capped by one arene group.
As already proposed for compounds 1 and 2, hydrogen
bonding is expected to exist between N1 and O12 and N2 and
O22. The water molecules (O01, O01A) appear in symmetry-
related pairs between the strings of complexes near the atoms
O11 and N2 and are most certainly linked there via hydrogen
bonds (Figure 10), but no refinement of the hydrogen positions
was possible from the data set collected for this structure with
its many heavy atoms.
Figure 5. Dimerization in the crystalline phase of C8H8NO2Tl, 2 (ORTEP
drawing with 50% probability ellipsoids and atomic numbering).
Thallium(I) 2-hydroxy-benzoate (salicylate, 4). The crystal
structure of compound 4 has also been determined very recently
and independently by Kristiansson as part of a study on
complexes of monovalent thallium ions with functionalized
benzoate ligands.4 Our results are in full agreement with the
published data. To summarize, two formula units appear as
dimers similar to those of the anthranilate 1, but the aggregation
of these flat dimers into strings (cf. Figures 2, 3) leads to two
η6-coordinated arene units at each thallium atom. In addition, a
hydroxy group of a neighboring salicylate unit has a close
contact with a given metal atom which resembles the N-Tl
contact of an anthranilate unit in complex 1. The Tl+ cations in
the salicylate 4 are therefore the most shielded metal atoms of
the whole series (4 oxygen donors and two phenyl rings). No
Tl-Tl contacts are discernible.
Thallium(I) 2-hydroxy-3-methyl-benzoate (3-methyl-sali-
cylate, 5). Crystals of compound 5 are triclinic, space group
P1h, with two formula units in the unit cell. The monomeric
unit features a benzoate-chelated thallium atom and a hydrogen
bond between the hydroxy group and one of the carboxylate
oxygen atoms. These monomers are arranged in stacks with
Tl1-Tl1A contacts of 3.921 Å and all Tl atoms on a straight
line which is tilted against the planes of the monomers by about
65° (Figure 11). These geometrical parameters make significant
thallophilic bonding very unlikely.
Figure 6. Aggregation of dimers in the crystal structure of 2 resulting in
the formation of stair-like chains. The thallium atoms are partially shielded
through Tl-(arene) contacts. Selected bond lengths [Å], angles [°] and
symmetry transformations: Tl(1)-O(1) 2.572(7), Tl(1)-O(2) 2.779(7), Tl-
(1)-O(1B)1 2.676(7), Tl(1)-O(2A)2 2.757(7), Tl-XD3(centroid) 3.230-
(10); O(1)-Tl(1)-O(1B)1 73.9(2), O(1)-Tl(1)-O(2A)2 73.7(2), O(1B)1-
Tl(1)-O(2A)2 80.1(2), O(1)-Tl(1)-O(2) 49.0(2), O(1B)1-Tl(1)-O(2)
122.4(2), O(2A)2-Tl(1)-O(2) 77.5(2), Tl(1)-O(1)-Tl(1B)1 106.1(2); 1 -x,
2
3
-y, -z; -x, y, -z - 1/2; x, -y, z + 1/2.
of four-membered rings (Tl2O2) and (TlCO2) in the forms of a
wedge, a flat rhombus and a folded rhombus. Complexation of
the metal atom through four oxygen atoms in a small quadrant
of the coordination sphere is supplemented by a weak Tl-
(arene) contact (Tl1-XD (centroid) 3.230(11) Å). Contrary to
the situation in 1 the nitrogen atoms of compound 2 are not
coordinated to the thallium atoms [Tl1-N1 4.157(15) Å].
Along each string the almost perfectly planar dimeric units
shown in Figure 5 are arranged parallel as indicated by the
sidewise projection shown in Figure 6, but there is no phenyl
stacking. An alternative projection along the columns in the unit
cell shows that there are no conspicuous contacts between
neighboring amino-methyl-benzoate ligands. However, the
thallium atoms have become located on two opposite sides of
each column and are directly exposed to the thallium atoms of
the neighboring columns (Figure 7). The contacts between
neighboring zigzag chains of metal atoms [4.054(14) Å] are
longer than in 1 and make it doubtful that there are any
significant bonding contributions at these distances. This ar-
rangements leaves the metal atoms with an extreme undersupply
of ligand donor atoms.
Neighboring stacks of this type are indented meaning that
neighboring monomers of different stacks are not on the same
level but shifted to make the distances of a given Tl atom to
two monomers of the second stack about equal: Tl1-O1C
2.882(5), Tl1-O1D 2.902(5) Å. It is therefore not justified to
take any two monomers of different stacks as an independent
dimer similar to those selected in all four previous structures
(1-4). In the double-stacks each thallium atom is provided with
two additional oxygen atoms (O1C and O1D for Tl1) making
it four-coordinated (Figure 11), whereas in the previous
structures there was only one closely neighboring unit in the
Thallium(I) 2-amino-4-methyl-benzoate (4-methyl-anthra-
nilate semihydrate, 3). Crystals of compound 3 are monoclinic,
space group C2/c, with Z ) 16 formula units in the unit cell
9
3626 J. AM. CHEM. SOC. VOL. 125, NO. 12, 2003

Thallium(I) Anthranilates and Salicylates
A R T I C L E S
Figure 7. Cell plot of the crystalline phase of 2. In contrast to 1, no metallophilic interactions between adjacent strings are observed.
Figure 8. Asymmetric unit in the structure of C8H9NO2.5Tl, 3, with atomic
numbering (ORTEP drawing with 50% probability ellipsoids).
Figure 10. Pairs of symmetry-related water molecules are located in the
voids between the tetramers in 3, most probably stabilizing the crystalline
phase through a set of hydrogen bonds.
Figure 9. In the crystal structure of 3, four-membered Tl2O2-rings are fused
to eight-membered Tl2C2O4-rings. Neighboring formula units offer their
benzene rings for Tl-(arene) complexation. Selected bond lengths [Å],
angles [°] and symmetry transformations: Tl(1)-O(11) 2.601(11), Tl(1)-
O(12) 2.719(11), Tl(1)-O(21A)1 2.793(11), Tl(1)-X1B2(centroid) 3.166-
(13), Tl(2)-O(22) 2.509(12), Tl(2)-O(11) 2.711(10), Tl(2)-O(21A)1
2.784(11), Tl(2)-X2B3(centroid) 3.181(15); O(11)-Tl(1)-O(12) 49.3(3);
O(11)-Tl(1)-O(21A)1 79.2(3), O(12)-Tl(1)-O(21A)1 74.7(3), O(22)-
Tl(2)-O(11) 69.0(3), O(22)-Tl(2)-O(21A)1 83.5(4), O(11)-Tl(2)-
O(21A)1 77.5(3), Tl(1)-O(11)-Tl(2) 94.2(3), Tl(2A)1-O(21)-Tl(1A)1
Figure 11. Alignment of adjacent formula units in the crystalline phase
of 5 is not determined by Tl-(arene) or Tl-Tl contacts, but by Tl-O
interactions instead. Note that each O1 oxygen atom has contact with three
thallium ions. Selected bond lengths [Å], angles [°] and symmetry
transformations: Tl(1)-O(1) 2.734(6), Tl(1)-O(2) 2.749(5), Tl(1)-O(1C)1
2.882(5), Tl(1)-O(1D)2 2.902(5), Tl(1)-O(3E)3 2.976(5); O(1)-Tl(1)-
O(2) 48.03(14), O(1)-Tl(1)-O(1C)1 85.88(17), O(2)-Tl(1)-O(1C)1 85.88-
(17), O(1)-Tl(1)-O(1D)2 65.85(18), O(2)-Tl(1)-O(1D)2 80.19(16),
O(1C)1-Tl(1)-O(1D)2 85.29(13), O(1)-Tl(1)-O(3E)3 111.75(15), O(2)-
Tl(1)-O(3E)3 64.59(15), O(1C)1-Tl(1)-O(3E)3 161.45(15), O(1D)2-Tl-
1
2
3
88.5(3); -x + 1/2, -y - 1/2, -z + 1; x, y - 1, z; x, y + 1, z.
adjacent stack providing only one oxygen donor atom and
making the thallium atom three-coordinated (see e.g., Figure
2).
1
2
(1)-O(3E)3 96.49(15); -x, -y + 2, -z + 2; -x + 1, -y + 2, -z +
3
2; -x + 1, -y + 1, -z + 2.
Neighboring double-stacks of monomers are packed in such
a way that each hydroxy-substituent can function as an additional
donor [Tl-O3E 2.976(5) Å] which finally rises the coordination
number of each thallium atom (solely with oxygen atoms) to
five (Figure 11). This set of five oxygen atoms covers just about
one hemisphere of the thallium environment and no other
contacts are discernible in the other half of the coordination
sphere.
Introduction of the methyl group in the 3-position of the
salicylate ligand is thus found to induce an aggregation of the
monomers in a new motif with the thallium cation solely
9
J. AM. CHEM. SOC. VOL. 125, NO. 12, 2003 3627

A R T I C L E S
Wiesbrock and Schmidbaur
Tl-O-Tl-O zigzag chains between double-stacks of mono-
mers.) (3) Donor substituents may be employed as ligands
(-NH2 in 1, but not in 2 and 3; -OH in 4 and 5, but not in 6).
(4) η6-Arene coordination contributes to the shielding of the
metal atoms in most cases (1, 2, 3, 4 and 6), but is absent for
the 2-amino-3-methyl-benzoate ligand (5). (5) There is no
discernible π-π-stacking or C-H‚‚‚π-embracing of the arene
moieties.43 (6) Hydrogen bonding of the -NH2/-OH groups is
only obvious for internal interactions of the ligand in each
monomer and plays no role in determining the supramolecular
assembly of the monomers. (7) All Tl-Tl contacts are very
long and thallophilic bonding seems to play no or only a very
minor role in determining the crystal structures.
From the above observations, it may be concluded that the
bonding of the ligands to the metal should be taken as largely
ionic which can explain the flexibility of the coordination
number and coordination geometry and the clear preference for
the hard oxygen atoms of the carboxylate group. This result is
in excellent agreement with recent solution studies using large-
angle X-ray scattering and EXAFS techniques.44
The attachment of the ligands in only one hemisphere of the
ligand environment indicates the role of the 6s2 lone pair of
electrons which is highly contracted by relativistic effects.5,27
Capping of parts of the coordination sphere by arene coordina-
tion33 at distances larger than 3.0 Å or through long Tl-Tl
contacts with distances near the sum of the van der Waals radii
of ca. 3.92 Å appear to contribute very little to the overall
stability of the aggregates as witnessed by the almost random
presence or absence of such interactions depending on only
small changes in the substituent pattern.45
Finally, it should be remembered that in the analogous
potassium anthranilate40 the metal cationsswith an ionic radius
not much smaller than that of thalliumsare completely sur-
rounded by oxygen donor atoms reaching coordination number
7. This comparison perhaps reflects best the effects of a
relativistically contracted 6s2 lone pair of electrons for the most
heavy elements of the Periodic Table. It is very tempting to
assume that the toxicity of thallium salts may be associated with
the pronounced asymmetry of coordination which is the most
obvious distinction from the symmetrical coordination of alkali
metals. However, other factors such as the affinity to sulfur also
contribute to the specific physiological effects of the heaviest
main group metals in the Periodic Table (Hg, Tl, Pb, and Bi).
Figure 12. Aggregation of the dimers (in the crystalline phase of 6 allows
for arene as well as for weak oxygen contacts which determine the mutual
positioning. Selected bond lengths [Å], angles [°] and symmetry transforma-
tions: Tl(1)-O(1) 2.626(4), Tl(1)-O(2) 2.764(4), Tl(1)-O(1A)1 2.778-
(4), Tl(1)-O(2C)2 3.158(4), Tl-XB3(centroid) 3.304(8); O(1)-Tl(1)-O(2)
48.52(11), O(1)-Tl(1)-O(1A)1 72.53(14), O(2)-Tl(1)-O(1A)1 73.02(11),
O(1)-Tl(1)-O(2C)2 137.05(10), O(2)-Tl(1)-O(2C)2 88.75(10), O(1A)1-
1
Tl(1)-O(2C)2 93.31(10), Tl(1)-O(1)-Tl(1A)1 93.18(12); -x, y, -z +
2
3
3/2; -x, -y, -z + 1; x, -y, z - 1/2.
coordinated with oxygen atoms of four different 2-hydroxy-3-
methyl-benzoate ligands.
Thallium(I) 2-amino-4-methyl-benzoate (4-methyl-salicy-
late, 6). Crystals of compound 6 are monoclinic, space group
C2/c, with Z ) 8 formula units in the unit cell. The asymmetric
unit contains only one monomer with a structure closely related
to that of 4 and 5. These monomers form a new type of dimer,
where two edges T11-O1/Tl1A-O1A form a butterfly-type
four-membered ring with the wedge-type four-membered rings
folded to the same side on opposite edges of the butterfly (Figure
12). This dimer has 2-fold symmetry with the C2 axis passing
through the middle of the Tl1-Tl1A folding edge.
Each thallium atom of a dimer has an oxygen atom O2 at a
rather distant contact [Tl1-O2C 3.158(4) Å] from a neighboring
dimer and is η6-coordinated to one phenyl ring of the same
ligand [Tl-XB (centroid) 3.304(8) Å]. Within one hemisphere,
the thallium atoms thus have three near and one more distant
oxygen neighbors and are further shielded by one benzene ring
(Figure 12). All Tl-Tl contacts are longer than 4.0 Å.
Introduction of a methyl group in the 4-position instead of
the 3-position of the salicylate ligand (6 vs 5) causes again a
new packing pattern for the same monomeric units with strongly
reduced oxygen coordination (from 5 to 3 + 1) at the thallium
atom, but a return to π-complexation previously found in the
substituent-free salicylate (4).
Experimental Section
All experiments were carried out in pure water. All reagents were
commercially available. Standard equipment was used throughout.
Thallium(I) 2-Amino-benzoate, 1. Anthranilic acid (0.436 g, 3.2
mmol) is dissolved in 20 mL of boiling water and Tl2CO3 (0.75 g, 1.6
mmol) is added with stirring. The reaction mixture is refluxed for 30
min and subsequently cooled to room temperature. The product
crystallizes in long, yellow, transparent needles; Yield 1.00 g (91%).
Calcd. for C7H6NO2Tl: C 24.69, H 1.78, N 4.13, Tl 60.00, O 9.40;
Found: C 24.66, H 1.79, N 4.23, Tl, 60.40, O 8.92% (from the
Conclusions
The structures of compounds 1 to 6 show the following
common features: (1) All formula units have the metal atom
chelated by the carboxylate group of the amino-/hydroxy-
benzoate ligand to give a wedge-like four-membered ring. (Only
Tl2 in compound 3 is not chelated, but has the ligand as a bridge
to a neighboring metal atom.) (2) These monomers form dimers
by establishing mutual Tl-O coordination generating rhomboid
four-membered rings. These dimers may be flat (1, 2, 4) or
highly folded (3, 6). (Only compound 5 is an exception, where
no discrete dimers are discernible and aggregation occurs in
difference to 100%). IR (KBr, cm-1): 3427, s, ν(O-H); 3321, s, νasym
-
(N-H); 3028, m, νsym(N-H); 1608, s, νasym(C-O), δ(N-H); 1577, s,
ν(CdC); 1526, s, ν(CdC); 1441, s, ν(CdC); 1376, s, νsym(C-O); 1316,
s, ν(C-N); 1249, s, δ(dC-H); 1157, s, δ(dC-H); 1028, w, δ(dC-
H); 862, m, γ(dC-H); 806, m, γ(dC-H); 748, m, γ(dC-H); 662,
(43) Janiak, C. J. Chem. Soc., Dalton Trans. 2000, 3885.
(44) Persson, I.; Jalilehvand, F.; Sandstro¨m, M. Inorg. Chem. 2002, 41, 192.
(45) Galka, C. H.; Gade, L. H. Inorg. Chem. 1999, 38, 1038.
9
3628 J. AM. CHEM. SOC. VOL. 125, NO. 12, 2003

Thallium(I) Anthranilates and Salicylates
A R T I C L E S
Table 1. Crystal Data, Data Collection, and Structure Refinement of Compounds 1 to 3, 5, and 6
Thallium(I)
Thallium(I)
2-amino-
3-methyl-
benzoate, 2
2-amino-
4-methyl-
benzoate
Thallium(I)
2-hydroxy-
3-methyl-
Thallium(I)
2-hydroxy-
4-methyl-
Thallium(I)
2-amino-
benzoate, 1
hemihydrate, 3
benzoate, 5
benzoate, 6
crystal data
formula
Mr
crystal system
space group
a (Å)
C7H6N1O2Tl1
340.50
orthorhombic
Pbca
13.5580(3)
5.9210(1)
18.1520(5)
90
C8H8N1O2Tl1
354.52
monoclinic
C2/c
21.8600(16)
7.8832(7)
9.7819(8)
90
101.012(5)
90
1654.6(2)
2.846
C8H9N1O2.5Tl1
363.53
monoclinic
C2/c
23.0796(8)
6.9008(2)
23.5642(10)
90
101.099(1)
90
C8H7O3Tl1
355.51
triclinic
P1h
3.9183(2)
7.9082(4)
13.8470(9)
95.824(2)
91.555(2)
104.296(4)
413.03(4)
2.859
C8H7O3Tl1
355.51
monoclinic
C2/c
20.1767(10)
7.3226(4)
11.4156(6)
90
103.584(3)
90
1639.43(15)
2.881
b (Å)
c (Å)
R (°)
â (°)
90
90
γ (°)
V (Å3)
1457.19(6)
3.104
8
3682.8(2)
2.623
16
F
calc (g cm-3
)
Z
8
2
8
F(000)
1216
22.108
1280
19.476
2640
17.508
320
19.511
1280
19.662
µ(Mo KR) (cm-1
data collection
measured refl.
unique refl.
)
21375
1551 [Rint ) 0.064]
12816
1829 [Rint ) 0.079]
26006
3972 [Rint ) 0.071]
15474
1697 [Rint ) 0.055]
34951
1814 [Rint ) 0.069]
abs. correction
T
min/Tmax
0.166/0.638
100
0.326/0.755
109
0.402/0.796
226
0.271/0.721
109
0.247/0.705
109
refinement
ref. parameters
final R values [I g 2σ(I)]
R1a
0.0278
0.0739
0.0480
0.0936
0.0614
0.1398
0.0329
0.0857
0.0355
0.0959
wR2b
2
2
2
2
2
2
a R1 ) Σ(||Fo| - |Fc||)/Σ|Fo|. b wR2 ) {[Σw(Fo - Fc )2]/Σ[w(Fo )2]}1/2; w ) 1/[σ2(Fo ) + (ap)2 + bp]; p ) (Fo + 2 Fc )/3; a, b: free variables. For
data of 4, See ref 4.
s, γ(N-H); 530, m, r(CO2). MS (CI); L ) deprotonated ligand: m/z
) 547, [205TlL + 205Tl]+; 545 [205TlL + 203Tl]+; 543 [203TlL + 203Tl]+;
342 [205TlL]•+; 340 [203TlL]•+; 298 [205TlL - CO2]•+; 296 [203TlL -
(
205TlL + HL - H2O + H)+; 343 (205TlL)•+; 341 (203TlL)•+; 326 (205TlL
- H2O + H)+; 324 (203TlL - H2O + H)+; 205 (205Tl)+; 203 (203Tl)+;
138 (HL)•+; 121 (HL - H2O + H)+.
CO2]•+; 205 [205Tl]+; 203 [203Tl]+; 137 [HL]•+; 119, [HL - H2O]•+
.
Thallium(I) 2-Hydroxy-3/4-methyl-benzoate, 5 and 6. As de-
scribed for 1, using 3/4-methyl-salicylic acid (0.487 g, 3.2 mmol each)
and Tl2CO3 (0.75 g, 1.6 mmol each) in 30 mL of water; yield 0.94/
1.06 g (82/93%). Calcd. for C8H7O3Tl: C 27.03, H 1.98, Tl 57.49, O
13.50; found: C 26.90/27.01, H 1.97/1.99, Tl 56.95/57.49, O 14.18/
13.51% (from the difference to 100%). IR (KBr, cm-1) for compound
5: 3500-2900, m, ν(C-H), ν(O-H); 1606, s, νasym(C-O), ν(CdC);
Thallium(I) 2-amino-3/4-methyl-benzoate, 2 and 3. The prepara-
tion follows the procedure given for compound 1 with 3/4-methyl-
anthranilic acid (0.483 g, 3.2 mmol each) and Tl2CO3 (0.75 g, 1.6 mmol
each); yield 0.99/0.56 g (87/49%). Calcd. for C8H8NO2Tl, 2: C 27.10,
H 2.27, N 3.95, Tl 57.65, O 9.03; found: C 27.05, H 2.29, N 3.94, Tl
57.10, O 9.62% (from the difference to 100%). Calcd. for C8H9NO2.5
-
Tl, 3: C 26.43, H 2.50, N 3.85, Tl 56.21, O 11.00; found: C 26.66,
H 2.36, N 3.87, Tl 56.40, O 10.71% (from the difference to 100%).
IR (KBr, cm-1) for 2: 3500-2900, m, ν(C-H), ν(N-H); 1603, s,
1557, m, ν(CdC); 1478, s, ν(CdC); 1441, m, ν(CdC); 1405, s, νsym-
(C-O); 1296, s, δ(O-H), 1255, m, δ(C-H); 1078, m, δ(C-H); 999,
m, δ(C-H); 912, m, γ(C-H); 834, m, γ(C-H); 779, m, γ(C-H); 745,
s, γ(C-H); 639, m, γ(O-H); 573, m, r(CO2). IR (KBr, cm-1) for
compound 6: 3500-2500, m, ν(C-H), ν(O-H); 1644, s, νasym(C-O),
ν(CdC); 1596, m, ν(CdC); 1504, s, ν(CdC); 1437, m, ν(CdC); 1375,
s, νsym(C-O); 1300, s, δ(O-H); 1255, m, δ(C-H); 1171, m, δ(C-
H); 1091, m, δ(C-H); 947, m, γ(C-H); 886, m, γ(C-H); 778, m,
γ(C-H); 704, s, γ(C-H); 618, m, γ(O-H); 592, m, r(CO2). MS
(CI) for compounds 5 and 6; L ) deprotonated ligand: m/z ) 765
[2 205TlL + 205Tl - 2 CO2 - 2 H2O - 2 CH2]+; 763 [2 205TlL + 203Tl
- 2 CO2 - 2 H2O - 2 CH2]+; 561 [205TlL + 205Tl]+; 559 [205TlL +
203Tl]+; 557 [203TlL + 203Tl]+; 356 [205TlL]•+; 354 [203TlL]•+; 339 [205TlL
- H2O + H]•+; 337 [203TlL - H2O + H]•+; 313 [205TlL - CO2 +
H]+; 311 [203TlL - CO2 + H]•+; 205 [205Tl]+; 203 [203Tl]+; 152 [HL]•+;
νasym(C-O), ν(CdC); 1528, m, ν(CdC); 1462, s, ν(CdC); 1423, m,
ν(CdC); 1375, s, νsym(C-O); 1314, s, δ(O-H); 1240, m, δ(dC-H);
1082, m, δ(dC-H); 998, m, δ(dC-H); 890, m, γ(dC-H); 834, m,
γ(dC-H); 750, m, γ(dC-H); 630, m, r(CO2). IR (KBr, cm-1) for 3:
3435, s, ν(O-H); 3320, s, νasym(N-H); 3009, m, νsym(N-H); 1622, s,
νasym(C-O), δ(N-H); 1583, s, ν(CdC); 1508, s, ν(CdC); 1425, s,
ν(CdC); 1368, s, νsym(C-O); 1325, s, ν(C-N); 1254, m, δ(C-H);
1177, m, δ(C-H); 1149, s, δ(C-H); 950, m, γ(C-H); 856, s, γ(C-
H); 778, s, γ(C-H); 698, m, γ(C-H); 664, m, γ(C-H); 607, m, r(CO2).
MS (CI) for compounds 2 and 3; L ) deprotonated ligand; (*)
observable in the spectrum of compound 2 only: m/z ) 915 [3 205TlL
203
- 3 CO2 - NH3 + H]+; 913 [2 205TlL +
TlL - 3 CO2 - NH3 +
H]+; 560 [205TlL + 205Tl]+; 558 [205TlL + 203Tl]+; 556 [203TlL + 203Tl]+;
471(*) [205TlL + HL - NH3 - H2O]•+; 469(*) [203TlL + HL - NH3
- H2O]•+; 355 [205TlL]•+; 353 [203TlL]•+; 311 [205TlL - CO2]•+; 309(*)
135 [HL - H2O + H]+; 108 [HL - CO2]•+
.
X-ray Structure Determination. The crystalline samples were
placed in an inert oil, mounted on a glass pin and transferred to the
cold gas stream of the diffractometer. Crystal data were collected and
integrated with an Enraf-Nonius DIP 2020 image plate sytem (Silicon-
Graphics O2 workstation) with monochromated Mo KR (λ ) 0.71073
Å) radiation at -130 °C. The structures were solved by direct methods
using SHELXS-97 and refined by full matrix least-squares calculations
on F2 with SHELXL-97. Non-H-atoms were refined with anisotropic
[
[
203TlL - CO2]•+; 267(*) [2 HL - NH3 - H2O]•+; 205 [205Tl]+; 203
203Tl]+; 151 [HL]•+; 133 [HL - H2O]•+; 107 [HL - CO2]•+
Thallium(I) 2-hydroxy-benzoate, 4. Preparation, elemental analysis
.
and IR (KBr): ref 4. MS (CI); L ) deprotonated ligand: m/z ) 668
(2 205TlL - H2O + H)+; 666 (205TlL + 203TlL - H2O + H)+; 548
(
205TlL + 205Tl)+; 546 (205TlL + 203Tl)+; 544 (203TlL + 203Tl)+; 464
9
J. AM. CHEM. SOC. VOL. 125, NO. 12, 2003 3629

A R T I C L E S
Wiesbrock and Schmidbaur
thermal parameters. Protons of the water molecule in thallium(I)
2-amino-4-methyl-benzoate were neglected; all other H-Atoms were
calculated and allowed to ride on their parent atoms with fixed isotropic
contributions. Extinction corrections were applied for all the presented
compounds using DELABS. A summary of the crystal data, experi-
mental details and refinement results is listed in Table 1. Important
interatomic distances and angles are given in the corresponding figure
captions. Thermal parameters and complete tables of interatomic
distances and angles have been deposited with the Cambridge Crystal-
lographic Data Centre, 12 Union Road, Cambridge CB2 1 EZ, UK.
The data are available on request on quoting CCDS-202884 to CCDS-
202888, respectively.
Acknowledgment. This work was generously supported by
Fonds der Chemischen Industrie.
Supporting Information Available: X-ray crystallographic
files for 1, 2, 3, 5, and 6 (CIF). Crystal data, data collection,
structure refinement, thermal parameters, and complete tables
of interatomic distances and angles for 1, 2, 3, 5, and 6 (PDF,
26 pages, print/PDF). This material is available free of charge
via the Internet at http://pubs.acs.org.
JA0287783
9
3630 J. AM. CHEM. SOC. VOL. 125, NO. 12, 2003