Rectangular bimetallic diorganotin macrocycle obtained through a combination of metallosupramolecular chemistry with imine bond formation

Article abstract of DOI:10.1016/j.inoche.2013.09.035

Herein it is presented a combination of metallosupramolecular chemistry with imine bond formation in the one pot strategies, this is a two step multi-condensation procedure to prepare a bis-diorganotin(IV) macrocycle. First, the 2:1 condensation reaction

Full text of DOI:10.1016/j.inoche.2013.09.035

Rectangular bimetallic diorganotin macrocycle obtained through a combina-
tion of metallosupramolecular chemistry with imine bond formation
Nelly Gonz a´ lez-Rivas, Erick Cuevas-Ya n˜ ez, Victor Barba, Hiram I. Bel-
tran, Horacio Reyes
PII:
DOI:
Reference:
S1387-7003(13)00386-9
doi: 10.1016/j.inoche.2013.09.035
INOCHE 5249
To appear in:
Inorganic Chemistry Communications
Received date:
Accepted date:
3 April 2013
22 September 2013
Please cite this article as: Nelly Gonz ´a lez-Rivas, Erick Cuevas-Ya n˜ ez, Victor Barba,
Hiram I. Beltran, Horacio Reyes, Rectangular bimetallic diorganotin macrocycle obtained
through a combination of metallosupramolecular chemistry with imine bond formation,
Inorganic Chemistry Communications (2013), doi: 10.1016/j.inoche.2013.09.035
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ACCEPTED MANUSCRIPT
Rectangular bimetallic diorganotin macrocycle obtained through a
combination of metallosupramolecular chemistry with imine bond
formation.
a
a
b
c
Nelly González-Rivas, Erick Cuevas-Yañez, Victor Barba, Hiram I. Beltran and Horacio
d*
Reyes.
a
Centro Conjunto de Investigación en Química Sustentable UAEM-UNAM Carretera Toluca-
Atlacomulco Km. 14.5, Unidad San Cayetano, Toluca, Estado de México. 50200, México.
b
Centro de Investigaciones Químicas, Universidad Autónoma del Estado de Morelos, Av.
Universidad 1001, 62209 Cuernavaca, México.
c
Departamento de Ciencias Naturales, DCNI, Universidad Autónoma Metropolitana
Cuajimalpa. Avenida Pedro Antonio de los Santos 84, 11850 México D. F., México.
d
Facultad de Química, Universidad Autónoma del Estado de México, Avenida Paseo Tollocan
S/N, Toluca 50180 Estado de México, México
*
Corresponding author.
Email: hreyesp@gmail.com
1

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Abstract.
Herein it is presented a combination of metallosupramolecular chemistry with imine bond
formation in the one pot strategies, this is a two step multi-condensation procedure to prepare
a bis-diorganotin(IV) macrocycle. First, the 2:1 condensation reaction of 3-aminobenzoic acid
(1) with di-n-butyltin(IV) oxide in acetonitrile led a diorganotin(IV) building block. This
followed a second step through the [2+2] condensation reaction with terephthalaldehyde (2)
thus allowing the synthesis of a rectangular shaped 38-membered bis-iminic-diorganotin
macrocycle (3). X-ray analysis of the macrocycle co-crystal with 1,3,5-trimethyltrioxane
(paraldehyde) reveals a highly symmetric binuclear rectangular macrocyclic compound with
approximate dimensions of 17.4 Å (length) X 14.0 Å (width).
Keywords: Diorganotin (IV) macrocycles, Condensation reactions, Supramolecular
architectures.
2

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The metallosupramolecular chemical design is the most successful approach in the
construction of coordination and organometallic supramolecular architectures [1]. The
reaction of the metallic centers with the appropriate coordination number and geometry with
certain ligands has allowed the preparation of macrocycles and cages with diverse structures,
such as, rectangle [2], triangle [3], hexagon [4], tetrahedron [5], helicate [6], or the very
complicated and elegant stellated cuboctahedron [7]. On the other hand, in the field of the
purely organic chemistry, the dynamic covalent chemistry has lead to preparation of an
enormous amount of supramolecular structures [8]. Perhaps, the most used reaction in this
kind of chemistry is the condensation of the amines with the corresponding carbonyl
compounds to generate the Schiff bases [9].
Recently, the metallosupramolecular chemical design has been successfully combined with
dynamic covalent chemistry by using iminic condensation reactions with the macrocyclic
ligands in the first coordination sphere of metallic centers [10]. Due to the resulting reciprocal
stabilization of both the metal compound and the iminic bond, several interesting results have
been described in the last years, including, the synthesis of a nano-sized molecular cages [11]
and prisms [12]. Normally, the metal centers used in these reports are transition metals, in the
best of our knowledge this approach has never been reported in the field of diorganotin
compounds. In continuing with our studies in the synthesis and characterization of
diorganotin compounds with applications in medicinal [13] and materials chemistry [14], we
have decided to explore this approach in the design and synthesis of diorganotin macrocycles.
Herein, we firstly report the use of the combination of metallosupramolecular chemical design
with dynamic covalent chemistry in the engineering and synthesis of a 38-membered
binuclear diorganotin macrocycle.
As has been previously reported [15, 16], the tin atom in diorganotin bis(phenylcarboxylates)
is hexacoordinated with a trapezoidal geometry around the metal center, an important fact is
that the aromatic groups in the molecular structure are cis each other as was demonstrated by
X-ray diffraction analysis. We realized that this kind of arrangement is the most suitable one
to get discrete macrocycles, by condensing a diorganotin bis(phenylcarboxylate) containing
two pendant amino groups with the appropriate bis-carbonyl compound. In order to test this
hypothesis the reaction of 3-aminobenzoic acid (1) with dinbutyltin oxide was carried out to
get dinbutyl bis(-(3-aminophenyl)carboxylate) (2) which has two free amino groups, which
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are readily available for further condensation reactions. Then 2 was reacted with
terephthalaldehyde, yielding the macrocycle 3, the reaction equation is depicted in scheme 1.
When the isomeric 2-aminobenzoic and 4-aminobenzoic acids were used as starting materials
only intractable materials were obtained, even when the reactions were carried out under high
dilution conditions. This experimental observation pointed out the importance of having the
precise geometric requirements for a successful preparation of macrocycles instead of
oligomeric or polymeric compounds.
In order to demonstrate the importance of the pre-formation of the intermediate 2, two
additional reactions were carried out. The first one was the preparation of the di-iminic
compound 4 as the first step and its subsequent reaction with dibutyltin oxide as is shown in
scheme 2. Nevertheless, the reaction yielded an intractable mixture of polymeric compounds
with no measurable amounts of 3. The second experiment was the one step reaction, by
mixing, 3-aminobenzoic acid, dinbutyltin oxide and terphtalaladehyde in acetonitrile under
reflux, the results were also not encouraging.
The optimized synthetic procedure for the obtaining of 3 is a one-pot reaction without
purification of intermediate 2. The reaction of 3-aminobenzoic acid with dinbutyltin oxide in
acetonitrile under reflux afforded the intermediate 2 in quantitative yield. The progress of the
reaction is readily observed by dissolution of the dinbutyltin oxide, which is insoluble at the
beginning, nevertheless when it reacts with carboxylate groups slowly dissolves in the
reaction media. When all of the dinbutyltin oxide has dissolved, and a homogeneous liquid is
formed the reaction is essentially complete, then the addition of terephthalaldehyde in one
portion followed by three hours of reflux allows the preparation of 3. After the cooling down
of the reaction at room temperature, a yellow solid precipitate was obtained and filtered under
vacuum. The macrocyclic compound was recrystallized from chloroform-hexanes and product
was obtained in almost quantitative yield. FAB-MS analysis revealed a peak at m/z = 1408
with the typical pattern for two tin atoms present into the same discrete molecular
1
architecture, providing a strong evidence for the proposed macrocyclic structure. In the H
1
3
and C NMR spectra recorded at room temperature in CDCl , a single set of signals was
3
observed for a fourth of those present in the claimed molecule, indicating a highly symmetric
structure in solution [17]. Only one signal was found for the iminic group both for hydrogen
(8.15 ppm) and also for carbon nuclei (175.8 ppm) also underlying the symmetry of the
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1
19
macrocycle. The Sn NMR spectroscopic analysis is the most useful tool for determining the
1
19
coordination number of tin and its stereochemistry. The Sn NMR spectrum of 3 shows a
single quite broad signal at -150.69 ppm, indicating that the tin atom exhibits fluxional
behavior in non-coordinating solvent solution between five and six-coordinate environment in
the distannoxane moiety.
The firsts attempts to obtain crystals of 3 were unsuccessful, a series of single and combined
solvents were tried. In some cases some good crystals were obtained, nevertheless they loss
the solvent very easily, making them fragile, hence preventing to have good diffraction data
followed by decay due to X-ray irradiation. We realized that the large size of the structure
could give large solvent accessible voids, which allows the solvent to escape from the crystal
lattice; additionally the compound is very hydrophobic allowing only the capture non-polar
solvents. To overcome this difficulty we decided to use non-polar solvents and compounds
with higher molecular volumes in the crystallization process, a slow evaporation of a
combination of 1,3,5-trioxane with hexane yielded good quality single crystals suitable for X-
ray diffraction determination as will be seen forthcoming.
The X-ray diffraction analysis [18, 19] confirmed that diorganotin macrocycle 3 adopts a
rectangle like structure with approximate dimensions of 17.4 Å (length) X 14.0 Å (width), and
the presence of two hexacoordinate tin atoms in a trapezoidal geometry was observed (figure
1
). The macrocyclic compound is almost completely planar, only the aromatic rings from
terphtalaldehyde moiety are slightly deviated from the ideal. The constructed cavity is
completely hydrophobic since only aromatic rings are part of its interior, this was confirmed
for the supramolecular network found in the crystal (figure 2), in which is possible to observe
the inclusion of the CH -CH - moiety of nbutyl groups from two different macrocycles inside
3
2
the cavity of one of its neighbors, filling up almost the entire free volume. Also it is possible
to found the 1,3,5-trioxane molecules in the top and the bottom at the center of the
macrocycle, showing that compound 3 packs in an inefficient manner leading to large
accessible voids (figure 3) also stated by the low calculated density of the crystalline structure
-1
of 1.409 gmL . The latter finding could allow the obtaining of several crystalline inclusion
complexes, as a matter of fact the research in that direction is currently pursued in our group.
In conclusion, we have demonstrated that it is possible to obtain molecular architectures with
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a well-defined topology through right step by step combining organotin carboxylate ligand
reaction with Schiff base condensation in a way defined previously as orthogonal fashion
[
10]. This approach should be applicable in the preparation of a variety of some other
molecules with well-defined architectures interesting for further biological as well as
industrial applications.
Acknowledgements
The authors acknowledge funds from UAM, PROMEP and CONACyT.
Supplementary material
CCDC 932251 contains the supplementary crystallographic for 3. These data can be obtained
free of charge from The Cambridge Crystallographic Data Centre via
http://www.ccdc.cam.ac.uk/data_request/cif
References and notes
[
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4
[
[
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5
193-5198.
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855.
[
[
2
[
(
[
[
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2011), 10764-10767.
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Chem. Int. Ed. 41 (2002) 898-952.
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[10] A. Granzhan, T. Riis-Johannessen, R. Scopelliti, K. Severin, Angew. Chem. Int. Ed. 49
(2010) 5515-5518.
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[
11] A. Granzhan, C. Schouwey , T. Riis-Johannessen , R. Scopelliti, K. Severin, J. Am.
Chem. Soc. 133 (2011), 7106-7115.
[
[
12] M. Schmittel, M. L. Saha, J. Fan, Org. Lett. 13 (2011) 3916-3919.
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Apan, J. Inorg. Biochem. 101 (2007) 1070-1085.
14] J. M. Rivera, H. Reyes, A. Cortes, R. Santillan, P. G. Lacroix, C. Lepetit, K. Nakatani, N.
Farfan, Chem. Mater. 18 (2006) 1174-1183.
15] S. P. Narula, S. K. Bharadwaj, H. K. Sharma, Y. S. G. Mairesse, J. Organomet. Chem.
15 (1991) 203-209.
16] T. S. B. Baula, C. Masharinga, S. Basua, C. Pettinari, E. Rivarola, S. Chantrapromma,
H. K. Fune, Appl. Organometal. Chem. 22 (2008) 114-121.
[
[
4
[
-1
[
17] Yellow microcrystalline powder. Mp. >300 °C dec. IR (KBr, cm ): , 1718, 1620,
1
1
2
580, 1524 , 582, 533, 427, 327, 278. H NMR (CDCl , 293 K): δ, 0.93 (t, 3H,), 1.46 (sxt,
3
H,), 1.80 (m, 2H), 1.89 (m, 2H), 7.55 (m, 1H), 8.03 (m, 1H), 8.10 (s, 2H), 8.15 (s, 1H), 8.68
1
3
(
s, 1H). C NMR (CDCl , 293 K): δ, 13.58, 25.61, 26.39, 26.71, 121.68, 127.32, 128.27,
3
119
1
1
29.24, 129.31, 131.07, 138.66, 151.64, 160.20, 175.83. Sn NMR (CDCl , 293 K): δ, -
3
59.69.
[
18] The X-ray diffraction study of 3 was carried out on a BRUKER APEX diffractometer
with a CCD area detector (Mo-K=0.71073A˚, monochromator: graphite). Frames were
2
collected at T = 100 K. The measured intensities were reduced to F and corrected for
absorption with SADABS (SAINT-NT) [20]. Corrections were made for Lorentz and
polarization effects. Structure solution, refinement, and data output were carried out with a
SHELXTL-NT program package [21] program.
[
19] X-ray data: Triclinic, a = 11.549(5), b = 12.152(5), c = 13.877(6) Å,  = 75.241(6),  =
3
6
7.090(6)  = 86.332(7)°, space group P-1, V = 1733.5(13) Å , T= 100 K, Z = 3,  = 1.409
-1
-1
gmL m = 0.070 mm , 13609 reflections collected, independent 5002 [R(int) = 0.0360], R
1
[
[
[
I >2s(I)]= 0.0368, wR (all data) = 0.0398, GOF = 1.177, 420 parameters.
2
20] Bruker Analytical X-ray Systems, SAINT-NT Version 6.04, 2001.
21] Bruker Analytical X-ray Systems, SHELXTL-NT Version 6.10, 2000.
7

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Bu Bu
Sn
O
O
O
O
N
N
N
Bu Bu
Sn
O
O
O
OH
O
O
Terphtaldehyde
(
Bu) SnO
2
CH CN/reflux
CH CN/reflux
3
3
NH2
NH2
NH2
N
1
2
O
O
Sn
O
O
Bu
Bu
3
Scheme 1.
8

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O
N
OH
O
OH
(
Bu) SnO
2
Terphtaldehyde
3
CH CN/reflux
3
CH CN/reflux
3
NH2
4
N
1
OH
O
Scheme 2.
9

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O
O
OH
(
Bu) SnO
2
3
+
CH CN/reflux
3
NH2
O
1
Scheme 3.
10

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Figure 1. Ortep representation of 3, ellipsoids at 70% of probability.
11

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Figure 2. Solid state arrangement of 3 co-crystal.
12

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Figure 3. Molecular structure of 3 showing the interactions of butyl chains with the central
macrocycle. a) Lateral view with inserted CH -CH - moiety, b) top view with inserted CH -
3
2
3
CH - moiety; and c) three molecules showing the actual arrangement. In all the three figures
2
the 1,3,5-trioxane molecule is omitted for clarity.
13

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Graphical abstract sypnosis
Combining metallosupramolecular chemistry with imine bond formation in a one pot two step
multi-condensation procedure allows the preparation of a rectangle shaped bis-
diorganotin(IV) macrocycle
14

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Highligths
Combining metallosupramolecular chemistry with imine bond formation allows the
preparation of a rectangular diorganotin macrocycle.
This is a very simple one pot, two steps procedure.
The molecule is a highly symmetric binuclear rectangular cyclic compound with dimensions
of 17.4 Å (length) X 14.0 Å (width).
The macrocycle has a very hydrophobic cavity and form co-crystals with a bulky hydrophobic
molecules.
15