metal-organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
IR spectroscopy of the free ligand and the complexes
revealed: (i) the disappearance of the ꢀ(NÐH) absorption at
1
3167 cm as a consequence of the deprotonation of HAP4P
ISSN 0108-2701
(2-Acetylpyridine-jN 4-phenylthio-
semicarbazonato-j2N1,S)halogeno-
trans-dimethyltin(IV) (halogeno =
chloro and bromo)
for complexation through N2, (ii) the ꢀ(C N) absorption
1
bands at 1597 and 1528 cm found in the free ligand are
1
shifted to 1594 and 1549 cm in the chloro complex, and to
1
1595 and 1531 cm in the bromo complex, con®rming coor-
Regina H. P. Francisco,a* M. Teresa do P. Gambardella,a
b
c
Â
Gerimario F. de Sousa and Anuar Abras
dination via N2 (Labib et al., 1996), (iii) the ꢀ(C S) vibrations
a
1
in the free ligand at 1287 and 1218 cm are shifted to lower
Â
Instituto de Quõmica de Sao Carlos, Universidade de Sao Paulo, Caixa Postal 870,
Ä
Ä
b
frequencies by 35±69 cm 1. The same trend is exhibited by the
Â
13560.970 Sao Carlos, SP, Brazil, Instituto de Quõmica, ICC, Universidade de
Ä
c
Â
Â
Â
Brasõlia, 70910.900 Brasõlia, DF, Brazil, and Departamento de Fõsica, ICEx,
Universidade Federal de Minas Gerais, 30161.970 Belo Horizonte, MG, Brazil
Correspondence e-mail: reginap@iqsc.sc.usp.br
1
absorption at 896 cm attributed to ꢀ(C S), found in the
spectra of both complexes at 852 cm 1. These observations
and the appearance of bands with ꢀ(CÐS) character at
762 cm 1 in the spectra of the complexes suggest coordination
through thiocarbonyl sulfur (Ferrari et al., 1991). The far IR
Received 29 July 1999
Accepted 29 November 1999
1
spectral bands observed at 355 and 410 cm for [Sn(AP4P)-
1
(CH3)2Cl] and at 353 and 410 cm for [Sn(AP4P)(CH3)2Br]
A thiosemicarbazone derivative, 2-acetylpyridine 4-phenyl-
thiosemicarbazone, was prepared and complexed to Lewis
acids, Sn(CH3)2X2,
[SnX(C14H13N4S)(CH3)2], were characterized by single-crystal
were tentatively assigned to ꢀ(SnÐN) and ꢀ(SnÐS) modes,
respectively (Barbieri et al., 1993; Casas et al., 1994).
1
The H NMR (200 MHz) spectrum in CDCl3 of the chloro
X = Cl and Br. The products,
È
X-ray diffraction, and IR, NMR and Mossbauer spectro-
derivative showed two singlets in the methyl region, at 1.60
and 1.18 p.p.m. [2J(119SnÐCH3) = 96.4 Hz] due to two
magnetically non-equivalent methyl groups bonded in
scopies. They are isomorphous and crystallize in the mono-
clinic space group P21/n. The structure determination revealed
discrete neutral complexes with the SnIV atom in a distorted
octahedral coordination geometry, with the halogeno ligand
and the thiosemicarbazone derivative in the equatorial plane
and the methyl groups in axial positions.
N
CÐCH3 and SnÐCH3, respectively. The spectrum in CCl4
of [Sn(AP4P)(CH3)2Br] showed similar singlets at 1.56 and
2.48 p.p.m. [2J(119SnÐCH3) = 73.0 Hz].
Similar results were reported for trigonal bipyramidal
complexes with analogous coordination geometry, [Me2Sn-
Cl2ImSOMe] [ImSOMe
=
1-methyl-2-(methylsul®nyl)-
Comment
imidazole] and [Me2SnClFPT] (FPT = 2-formylpyridine
thiosemicarbazone) (Sousa et al., 1996; Labib et al., 1996). In
these cases, the tin±proton coupling constants, 2J(119SnÐ
CH3), are 91.45 (acetone-d6) and 96.0 Hz (DMSO-d6),
respectively. These data suggest that in solution, these
complexes, which are pentacoordinated and have ambidentate
N,N,S-Tridentate-N(4)-heterocyclic thiosemicarbazones de-
rived from 2-formyl- and 2-acetylpyridine include important
classes of compounds with biological activity (West et al., 1991,
1998; Labib et al., 1996).
The chelating behaviour of N,N,S-tridentate thio-
semicarbazones revealed three coordination modes. They can
act as a neutral N(azomethine),S-bidentate ligand (Barbieri et
al., 1993) and as an anionic (1 ) ligand, bonded through
N,N,S or through N(azomethine),S (Bamgboye & Bamgboye,
1988; Labib et al., 1996).
The structure determination of the compounds
[Sn(AP4P)(CH3)2Cl], (I), and [Sn(AP4P)(CH3)2Br], (II),
where HAP4P = 2-acetylpyridine 4-phenylthiosemicarbazone,
con®rmed that they are isomorphous. The chloro derivative is
shown in Fig. 1. The crystal structure is built up by discrete
molecules. The SnIV atom has a strongly distorted octahedral
coordination geometry, with the equatorial plane occupied by
the halogen ligand and the thiosemicarbazone derivative. The
methyl groups are in apical positions. Selected bond para-
meters are given in Tables 1 and 2.
Figure 1
View of (I) with displacement ellipsoids plotted at the 50% probability
level.
ꢀ
Acta Cryst. (2000). C56, 187±189
Regina H. P. Francisco et al. [SnBr(CH3)2(C14H13N4S)] and [Sn(CH3)2(C14H13N4S)Cl] 187
Francisco, Regina H. P.
