Preparation and structural characterization of [Ph3Sn(IV)] + complexes with pyridine-carboxylic acids or hydroxypyridine, -pyrimidine and -quinoline

Article abstract of DOI:10.1016/j.jorganchem.2005.12.019

A number of [Ph₃Sn(IV)]⁺ complexes formed with ligands containing -OH (-CO), or -COOH group(s) and aromatic {N} donor atom have been prepared. The binding sites of the ligands were identified by FT-IR spectroscopic measurements. In the complexes containing hydroxy and carboxylate functions, the carboxylato group is coordinated to the organotin(IV) centres in monodentate or bridging bidentate manner. It was also found that in the hydroxypyridine and -pyrimidine complexes the [Ph₃Sn(IV)]⁺ moiety in most cases reacts with the phenolic form of the ligands. The rationalisation of the experimental ¹¹⁹Sn M?ssbauer nuclear quadrupole splittings, |Δ_exp| - according to the point charge model formalism - together with the FT-IR data support the formation of trigonal bipyramidal (Tbp) or octahedral (O_h) molecular structures. Furthermore, X-ray diffraction analysis has been performed on the triphenyltin(IV)-3-phenolato-2(1H)-pyridinone-O,O′ single crystals. The penta-coordinated tin center exhibits a Tbp geometry. In case of 2-picolinic acid, a trans-phenylation was observed during the complexation, resulting [Ph₂Sn(IV)]²⁺ complex and Ph₄Sn(IV).

Full text of DOI:10.1016/j.jorganchem.2005.12.019

Journal of Organometallic Chemistry 691 (2006) 1622–1630
www.elsevier.com/locate/jorganchem
Preparation and structural characterization of [Ph3Sn(IV)]+
complexes with pyridine-carboxylic acids or hydroxypyridine,
-pyrimidine and -quinoline
a
b,
c
d
*
´
´
´
Attila Szorcsik , Laszlo Nagy , Michelangelo Scopelliti , Andrea Deak ,
c
b
b
´
´
´
Lorenzo Pellerito , Gabor Galbacs , Monika Hered
a
Bio-inorganic Chemistry Research Group of Hungarian Academy of Sciences, Department of Inorganic and Analytical Chemistry,
University of Szeged, PO Box 440, H-6701 Szeged, Hungary
b
Department of Inorganic and Analytical Chemistry, University of Szeged, PO Box 440, H-6701 Szeged, Hungary
c
`
Dipartimento di Chimica Inorganica e Analitica ‘‘Stanislao Cannizzaro’’, Universita di Palermo, Viale delle Scienze, Parco d’Orleans, 90128 Palermo, Italy
d
Institute of Structural Chemistry, Chemical Research Center of the Hungarian Academy of Sciences, PO Box 17, H-1525 Budapest, Hungary
Received 2 December 2005; accepted 2 December 2005
Available online 19 January 2006
Abstract
A number of [Ph3Sn(IV)]+ complexes formed with ligands containing –OH (–C@O), or –COOH group(s) and aromatic {N} donor
atom have been prepared. The binding sites of the ligands were identified by FT-IR spectroscopic measurements. In the complexes con-
taining hydroxy and carboxylate functions, the carboxylato group is coordinated to the organotin(IV) centres in monodentate or bridg-
ing bidentate manner. It was also found that in the hydroxypyridine and -pyrimidine complexes the [Ph3Sn(IV)]+ moiety in most cases
reacts with the phenolic form of the ligands. The rationalisation of the experimental 119Sn Mo¨ssbauer nuclear quadrupole splittings,
|Dexp| – according to the point charge model formalism – together with the FT-IR data support the formation of trigonal bipyramidal
(Tbp) or octahedral (Oh) molecular structures. Furthermore, X-ray diffraction analysis has been performed on the triphenyltin(IV)-3-
phenolato-2(1H)-pyridinone-O,O0 single crystals. The penta-coordinated tin center exhibits a Tbp geometry. In case of 2-picolinic acid,
a trans-phenylation was observed during the complexation, resulting [Ph2Sn(IV)]2+ complex and Ph4Sn(IV).
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Triphenyltin(IV); Hydroxypyridine, -pyrimidine and pyridinecarboxylato complexes; Mo¨ssbauer; FT-IR; X-ray diffraction
1. Introduction
It has recently been demonstrated that the reaction of pyr-
idine mono-and dicarboxylato anions with [Bu2Sn(IV)]2+ [3]
and [tBu2Sn(IV)]2+-cations [4] results in the formation of
polynuclear complexes. In these di-n-butyltin(IV) and di-t-
butyltin(IV) 2-picolinato and pyridine-2,6-dicarboxylato
complexes the central tin(IV)-ion is hepta- and penta-
coordinated in pentagonal-bipyramidal (Pbp) [3] and in
square-pyramidal (Sp) [4] environment. Later, a systemati-
cally designed series of complexes containing [Bu2Sn(IV)]2+
and [tBu2Sn(IV)]2+ ions and hydroxypyridine, hydroxypyr-
imidine and hydroxyquinoline ligands have also been
prepared. The structural data obtained reveal the influence
of the nature and steric position of donor atoms on the
It is well known that organotin(IV) compounds exhibit
high biological (for example fungicide and antitumor)
activity [1,2]. Organotin(IV) complexes with ligands con-
taining phenolic –OH or –COOH group(s), as well as, aro-
matic {N} donor atom represent an interesting class of
such complexes, however, up to now only a few works have
dealt with the molecular structures of them.
*
Corresponding author. Tel.: +36 62 544335/3557; fax: +36 62 420505.
E-mail address: laci@chem.u-szeged.hu (L. Nagy).
0022-328X/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2005.12.019

A. Szorcsik et al. / Journal of Organometallic Chemistry 691 (2006) 1622–1630
1623
coordination sphere of the tin center. Accordingly, the
OH
molecular structures of the complexes were established by
FT-IR and Mo¨ssbauer-spectroscopy. Single-crystals of
complexes of 8-hydroxyquinolinate with [Bu2Sn(IV)]2+
and [tBu2Sn(IV)]2+ were prepared. The X-ray diffraction
studies revealed that the central {Sn} atoms are in cis-Oh
environment [5].
Therefore, as organic continuation of former works the
goal of present paper to demonstrate the influence on the
structure of the bulky [Ph3Sn(IV)]+ moiety within the com-
plexes formed.
OH
OH
OH
N
OH
OH
N
N
N
H2L4
HL2
HL1
HL3
OH
N
N
N
HO
N
OH
OH
HL7
2. Experimental
H2L5
H2L6
2.1. Starting materials
COOH
COOH
COOH
COOH
The triphenyltin-hydroxide (Ph3SnOH) and ligands
2-hydroxypyridine {HL1}, 3-hydroxypyridine {HL2},
4-hydroxypyridine {HL3}, 2,3-dihydroxypyridine {H2L4},
N
COOH
N
N
N
4,6-dihydroxypyrimidine
{H2L5},
2,4-quinolinediol
H2L11
HL9
HL8
HL10
{H2L6} and 8-hydroxyquinoline {HL7} were purchased
from Sigma–Aldrich. Ligands containing –COOH group(s)
as 2-picolinic (HL8), nicotinic (HL9), iso-nicotinic (HL10),
pyridine-2,3-(H2L11) pyridine-2,4-(H2L12), pyridine-2,5-
(H2L13), pyridine-2,6-(H2L14), pyridine-3,4-(H2L15) and
pyridine-3,5-dicarboxylic (H2L16) acids were purchased
from Fluka. All the starting reagents are of A.R. grade
and were used as purchased. The structures of the ligands
are shown in Scheme 1.
COOH
HOOC
HOOC
COOH
N
COOH
N
COOH
N
H2L12
H2L14
H2L13
COOH
COOH
HOOC
COOH
2.2. Syntheses
N
N
The complexes were prepared as described in [3],
according to the reaction described in Scheme 2. First,
the appropriate quantity of Ph3SnOH (2 mmol) was dis-
solved and refluxed in dry methanol (50 cm3) for 1 h.
Then methanolic solution (50 cm3) containing 2 mmol of
the monobasic (HL1–3,7–10) or 1 mmol of the dibasic
(H2L4–6,11–16) ligand was added to the solution of the
Ph3SnOH and refluxed for another 2 h. In the case of
dibasic ligands (H2L4–6,11–16) we have been used two dif-
ferent, 1:1 and 2:1 starting metal to ligand molar ratios
for the preparation of the compounds. The analytical
and spectroscopic studies reveal formation of complexes
with 1:1 M:L for ligands H2L4–6,14 and 2:1 for the rest
dibasic ligands.
Compounds 1, 4–8, and 13–16 were obtained via slow
evaporation of the solvent at room temperature and were
separated by filtration and washed with dry methanol.
The other compounds precipitated immediately from
the reaction mixture. The complexes were recrystallized
from methanol. The obtained compounds were white sol-
ids, except 2, 7, 13 and 15, which were yellow, 4 and 6,
which were light-brown. All of them were insoluble in
water and benzene. Compounds 1, 4, and 7–10 were
obtained as single crystals, while the others are amor-
phous solids. The synthesis and X-ray diffraction analysis
H2L15
H2L16
Scheme 1. Structure of the ligands studied.
nPh3SnOH + HnL → (Ph3Sn)nL + nH2O
Scheme 2. Preparation of the complexes.
of 8–10 were already reported [6–8]. The X-ray diffrac-
tion analysis of 9 and 10 showed that the Sn(IV) is
penta-coordinated in distorted Tbp environment, in
which the bulky phenyl groups are in equatorial posi-
tions. The complexes have a chain-like polymeric struc-
ture, where the monodentately co-ordinated –COOꢀ
group and the pyridine {N} atom act as bridges between
the neighbouring {Sn} atoms.
The analytical data are presented in Table 1 together
with other characteristic physical constants. Microanalyses
were performed at the Department of Organic Chemistry,
University of Szeged. The Sn contents were measured by
Inductively Coupled Plasma Atomic Emission Spectrome-
try (ICP) and found to correspond to the theoretically cal-
culated values.

1624
A. Szorcsik et al. / Journal of Organometallic Chemistry 691 (2006) 1622–1630
Table 1
Physical and analytical data [calculated % values in parentheses] on [Ph3Sn(IV)]+ complexes studied
Complex
Analysis (%)
C
Colour
M.p. (ꢁC)
H
N
Sn
[Ph3Sn(2-hpy)]n (1)
[Ph3Sn(3-hpy)]n (2)
[Ph3Sn(4-hpy)]n (3)
Ph3Sn(2,3-dhpy) (4)
[Ph3Sn(4,6-dhpym)(H2O)]n (5)
[Ph3Sn(2,4-dhq)]n (6)
Ph3Sn(8-hq) (7)
Ph2Sn(pica)2 (8)
[Ph3Sn(nica)]n (9)
61.29 (62.16)
63.53 (62.16)
62.78 (62.16)
59.43 (60.03)
54.04 (55.15)
63.43 (63.56)
65.29 (65.62)
55.37 (55.74)
61.74 (61.05)
60.69 (61,05)
58.90 (59.69)
60.58 (59.69)
58.91 (59.69)
57.79 (58.17)
58.38 (59.69)
60.01 (59.69)
4.15 (4.28)
4.36 (4.28)
4.24 (4.28)
4.09 (4.13)
4.09 (4.17)
4.09 (4.12)
4.16 (4.25)
3.46 (3.48)
4.13 (4.24)
4.02 (4.24)
3.79 (3.81)
3.95 (3.81)
3.42 (3.81)
3.38 (3.49)
3.73 (3.81)
3.83 (3.81)
3.05 (3.15)
3.21 (3.15)
3.18 (3.15)
3.07 (3.04)
5.73 (5.84)
2.76 (2.74)
2.78 (2.83)
5.37 (5.41)
3.03 (2.96)
2.76 (2.96)
1.55 (1.62)
1.66 (1.62)
1.57 (1.62)
2.59 (2.71)
1.59 (1.62)
1.64 (1.62)
25.93 (26.74)
27.27 (26.74)
26.47 (26.74)
25.54 (25.80)
24.28 (24.78)
23.03 (23.27)
23.54 (24.02)
22.62 (22.96)
24.93 (25.14)
25.07 (25.14)
27.13 (27.44)
27.29 (27.44)
27.08 (27.44)
22.92 (23.00)
27.25 (27.44)
27.87 (27.44)
White
Light-yellow
White
Light-brown
White
Light-brown
Yellow
Colourless
White
White
White
White
Yellow
White
119–121
204–207
270–273
173–176
99–101
105–108
130–132
>300
180–184
192–196
>300
[Ph3Sn(inica)]n (10)
[(Ph3Sn)2-2,3-pydca]n (11)
[(Ph3Sn)2-2,4-pydca]n (12)
[(Ph3Sn)2-2,5-pydca]n (13)
[Ph3Sn-2,6-pydca]n (14)
[(Ph3Sn)2-3,4-pydca]n (15)
[(Ph3Sn)2-3,5-pydca]n (16)
>300
132–136
148–152
136–140
232–235
Yellow
White
2.3. X-ray crystallography
atom on the N(1) nitrogen was found in the difference
map, and its position was refined. All other hydrogen
atomic positions were generated from assumed geometries
and a riding model was applied.
Crystal data and refinement parameters of complex 4
are summarised in Table 2. Intensity data were collected
on an Enraf-Nonius CAD-4 diffractometer with graphite
˚
monochromated Mo Ka radiation (k = 0.71073 A) using
2.4. FT-IR and Mo¨ssbauer spectroscopic measurements
the x–2h scan technique. Three standard reflections were
monitored every hour; these remained constant within
experimental error. The structure was solved by direct
methods (SHELXS-97) and refined by full-matrix least-
squares (SHELXL-97) [9]. All non hydrogen atoms were
refined anisotropically in F2 mode. The H(1) hydrogen
The FT-IR spectra of the ligands and those of the com-
plexes were measured on BioRad Digilab Division FTS-
65A instrument in the range 4400–400 cmꢀ1 in KBr pellets.
Mo¨ssbauer spectroscopic measurements were performed
as described in [3,4]. To determine the steric arrangement
of the Sn(IV) coordination sphere, the experimental quad-
rupole splitting (|Dexp|) values were calculated on the basis
of a simple, but general molecular orbital model, according
to the pqs concept [10] for all the possible symmetries of
tetra-, penta- and hexa-coordinated Sn(IV) binding involv-
ing three phenyl groups. The pqs values of the different
functional groups [11,12] are given in Table 3.
Table 2
Crystal data and structure refinement parameters for complex 4
Empirical formula
Formula mass
C23H19N1O2Sn
460.08
Crystal size [mm]
Colour
Crystal system
0.20 · 0.50 · 0.55
Colourless
Monoclinic
P21/c
Space group
3. Results and discussion
h Range for data collection (ꢁ)
2.47 6 h 6 34.95
10.916(1)
11.012(1)
16.723(2)
98.85(1)
1986.3(4)
4
1.539
1.303
920
˚
a [A]
3.1. X-ray structural studies
˚
b [A]
˚
c [A]
The molecular structure of 4 is shown in Fig. 1, selected
bond lengths and angles are listed in Table 4. The coordi-
nation geometry around the Sn(IV) center is a distorted tri-
gonal bipyramidal (s = 0.64) with the O(1) atom of the
ligand and C(1A) atom of the phenyl-group occupying
the axial positions of the coordination sphere [the O(1)–
Sn(1)–C(1A) angle is 161.6(1)ꢁ]. The other two phenyl rings
are in the equatorial plane, with C(1C)–Sn(1)–C(1B) angle
close to 120ꢁ (Table 4). The third equatorial position is
occupied by deprotonated oxygen O(2) atom of the ligand.
The 3-phenolato-2(1H)-pyridinone-O,O0 anion is coordi-
nated to the metal center in a bidentate chelating fashion
leading to a five-membered SnO2C2 ring with an O(1)–
Sn(1)–O(2) bite angle of 73.3(1)ꢁ.
b [ꢁ]
3
˚
V [A ]
Z
Dcalc [Mg/m3]
l [mmꢀ1
F(000)
]
Index ranges (ꢁ)
0 6 h 6 17;
0 6 k 6 17;
ꢀ26 6 l 6 26
9576
8710/0.0300
5600
No. of reflections collected
No. of independent reflections/Rint
No. of observed reflections I > 2r(I)
No. of parameters
248
Goodness-of-fit
0.958
R1 (observed data)
0.0466
wR2 (all data)
0.1241

A. Szorcsik et al. / Journal of Organometallic Chemistry 691 (2006) 1622–1630
1625
Table 3
The Sn(1)–O(1) and the Sn(1)–O(2) bond distances are
Partial quadrupole splitting (pqs) values of the functional groups used in
the calculations (in mmsꢀ1
˚
2.093(2) and 2.358(2) A, respectively. The axial C(1A)–
)
˚
Sn(1) bond distance [2.162(2) A] is somewhat longer (by
Td
Tbpa
Tbpe
Oh
˚
ꢁ0.03 A) than the Sn–C bond distances in the equatorial
˚
{R}
ꢀ1.37
ꢀ0.15
ꢀ0.94
ꢀ0.1
ꢀ1.13
0.06
ꢀ1.03
ꢀ0.11
0.083
0.177
ꢀ0.1
ꢀ0.1
ꢀ0.14
ꢀ0.27
0.2
plane [2.137(2) and 2.132(3) A]. The O(2) oxygen atom is
{COOꢀ}m
{COOꢀ}b
{–C@O}
˚
engaged in N–Hꢂ ꢂ ꢂO hydrogen bonds (2.26 A), which in
0.114
0.24
0.075
0.16
0.293
0.407
0.147
0.147
0.02
their turn link the adjacent molecules into infinite chains.
In addition, weak C–Hꢂ ꢂ ꢂO and C–Hꢂ ꢂ ꢂp interactions can
also be observed (Table 5).
{Npyridine
{Nheterocycle
{OH}
{Oꢀ}
}
ꢀ0.46
ꢀ0.46
ꢀ0.40
ꢀ0.37
–
ꢀ0.035
ꢀ0.035
ꢀ0.13
ꢀ0.21
0.18
}
ꢀ0.09
3.2. FT-IR spectroscopic characterization
{H2O}
0.43
Abbreviations: Td, tetrahedral; Tbpa, trigonal-bipyramidal axial; Tbpe,
trigonal-bipyramidal equatorial; Oh, octahedral; m, monodentate; b,
bidentate.
Information on the nature of the tin–ligand bonds can
be extracted from infrared absorption frequencies (Tables
6 and 7).
The bifunctional hydroxypyridine, hydroxypyrimidine
and hydroxyquinoline ligands can [13] to be existing in dif-
ferent hydroxy or ketone form. They are predominantly in
pyridone form in the solid state, but in complex formation
the hydroxy is the preferred form [14–16]. In the FT-IR
spectra of free HL1, HL3, H2L4, H2L5 and H2L6, there
are characteristic medium and strong bands in the spectral
regions 3210–3090 and 1680–1630 cmꢀ1 of the –NH and
–C@O groups (Table 6), respectively. These bands are
absent from the spectra of HL2 and HL7, because the ten-
dency of tautomerization to their keto form is small. The
broad mOH absorption band in the region 3400–
3200 cmꢀ1 arises from the strong intra- and intermolecular
hydrogen-bonding network of the free ligands.
In the spectrum of the free Ph3SnOH the medium sharp
band at 3618 cmꢀ1 is attributed to m(Sn–)OH vibration
mode, which is absent from the spectra of the complexes,
reflecting the deprotonation of this group in the complex-
formation process. The four typical weak bands relating
to the phenylic aromatic rings in the range 1762–
1876 cmꢀ1 in the spectra of the complexes clearly demon-
strate the presence of the [Ph3Sn(IV)]+ moiety in the
complexes.
Most of the spectra exhibit well developed, sharp bands.
However, the assignments are not always clear-cut because,
due to complex formation, the positions of many of the
Fig. 1. A view of the molecular structure of complex 4 showing the atom-
numbering scheme. Non-hydrogen atoms are shown as 50% probability
ellipsoids and hydrogen atoms are shown as open cycles.
Table 5
˚
Selected interatomic distances (A) and angles (ꢁ) for the hydrogen bonding
and C–Hꢂ ꢂ ꢂp interactions in complex 4a
˚
˚
D–Hꢂ ꢂ ꢂA
Hꢂ ꢂ ꢂA (A)
Dꢂ ꢂ ꢂA (A)
D–Hꢂ ꢂ ꢂA (ꢁ)
Table 4
˚
N(1)–H(1)ꢂ ꢂ ꢂO(2)a
C(3C)–H(3C)ꢂ ꢂ ꢂO(1)b
C(3C)–H(3C)ꢂ ꢂ ꢂCg3b
C(5A)–H(5A)ꢂ ꢂ ꢂCg1c
C(6)–H(6)ꢂ ꢂ ꢂCg2a
2.26
2.60
3.18
3.28
3.39
3.37
3.04
3.40
3.72
3.60
4.17
4.03
163
145
119
103
143
130
Selected interatomic bond lengths (A) and bond angles (ꢁ) for complex 4
Sn(1)–O(1)
Sn(1)–O(2)
Sn(1)–C(1A)
Sn(1)–C(1C)
Sn(1)–C(1B)
O(2)–C(3)
O(1)–C(2)
C(3)–C(2)
2.358(2)
2.093(2)
2.162(2)
2.137(2)
2.132(3)
1.340(3)
1.262(3)
1.447(3)
1.350(3)
1.364(4)
C(1B)–Sn(1)–C(1C)
O(1)–Sn(1)–O(2)
116.9(1)
73.3(1)
84.1(1)
84.6(1)
161.6(1)
89.0(1)
111. 8(1)
123.4(1)
107.6(1)
101.7(1)
O(1)–Sn(1)–C(1B)
O(1)–Sn(1)–C(1C)
O(1)–Sn(1)–C(1A)
O(2)–Sn(1)–C(1A)
O(2)–Sn(1)–C(1B)
O(2)–Sn(1)–C(1C)
C(1B)–Sn(1)–C(1A)
C(1C)–Sn(1)–C(1A)
C(6A)–H(6A)ꢂ ꢂ ꢂCg4c
Cg1, Cg2, Cg3 and Cg4 are the centroids of the Sn(1)/O(1)/C(2)/C(3)/O(2)
(chelate), C(1A)/C(2A)/C(3A)/C(4A)/C(5A)/C(6A), C(1B)/C(2B)/C(3B)/
C(4B)/C(5B)/C(6B) and C(1C)/C(2C)/C(3C)/C(4C)/C(5C)/C(6C) rings.
a
N(1)–C(2)
N(1)–C(6)
Symmetry codes: (a) ꢀx, ꢀ1/2 + y, 1/2ꢀz; (b) x, 3/2 ꢀ y, ꢀ1/2 + z; (c)
ꢀx, 2 ꢀ y, ꢀz.

1626
A. Szorcsik et al. / Journal of Organometallic Chemistry 691 (2006) 1622–1630
Table 6
Assignment of characteristic FT-IR vibrations (cmꢀ1) of hydroxypyridines, hydroxypyrimidine and hydroxyoxyquinolines and their triphenyltin(IV)
complexes
mOH
mNH
mC@O
ma,s C@C/N@C
mCO(Sn)
cPh@CH
maSnC
msSnC
mSnO
HL1
1
–
3150 m
1683 m,
1649 vs
–
1608 s, 1575 s, 1539 s, 1455 m
–
–
–
–
–
3436 w
3424 w
–
–
1606 vs, 1542 m
1492 m, 1437 m
1574 vs, 1540 sh,
1155 w 1079 w
–
731 s 693 vs
–
562 w
–
516 w
–
446 m
–
HL2
–
1479 vs, 1445 sh
2
3432 w
–
–
–
1577 m, 1560 m 1479 s
1548 s, 1507 vs, 1428 msh,
1182 w 1127 w
–
730 m 697 s
–
582 m
–
–
–
454 m
–
HL3
3205 m
1670 sh,
1633 vs
–
1676 s,
1664 vs
1627 m
3
3421 w
3270 m
–
1510 vs, 1480 m
1613 m, 1579 m,
1446 w, 1412 w
1190 s
–
729 m 697 s
–
586 w
–
–
–
455 m
–
H2L4
3240 m
4
–
–
3245 w
–
1550 m, 1479 w 1426 m
1155 w 1102 w
–
729 m 700 m
–
597 m
–
485 w
–
451 m
447 m
–
H2L5
1681 m,
1642 s
1607 vs, 1585 s,
1521 m, 1445 m
5
3424 w
3380 w
3242 w
3093 m
1650 s
1689 vs
1609 m, 1497 m 1428 m
1610 s, 1594 vs, 1551 w,
1505 m, 1471 s, 1420 s
1593 vs, 1514 m
1080 m 1063 m
–
730 m 693 m
–
628 w
–
539 m
–
451 m
–
H2L6
6
–
3343 w
1624 s
1106 w 1076 w
730 m 698 m
–
570 w
–
460 m
455 m
–
HL7
7
3470 w
–
–
–
–
–
1580 m, 1509 vs, 1473 s,
1434 m
1575 m, 1496 s, 1465 s
–
–
–
–
1106 w
730 m 699 m
523 m
452 m
444 w
Abbreviations: s, strong; m, medium; w, weak; vs, very strong; sh, shoulder.
Table 7
Assignment of characteristic FT-IR vibrations (cmꢀ1) of pyridine-carboxylic and -dicarboxylic acids (dca) and for [Ph3Sn(IV)]+ complexes
mOH
mC@O
maCOOꢀ
msCOOꢀ
DmCOOꢀ
mC@C/N@C
maSnC
msSnC
mSn–O
HL8
8
3443 bw
–
3462 bw
3444 bw
–
–
3453 gy
3368 bw
3523 bm
–
1721 bw
–
1707 m
–
1712 bs
–
1711 gy
–
1794 bm
–
1730 vs
–
1702 vs
1692 m
1712 bm
3419 bw
1721 bs
–
1594 m
1679 vs
–
1653 vs
1616 m
1646 s
1606 s
1691 vs, 1658 s
1611 s
1678 vs, 1661 s
1596 m
1642 vs, 1627 s
–
1625 vs
1608 m
1678 s, 1661 vs
–
1444 w
1332 m
–
1350 m
1411 s
1348 m
1423 m
1321 s, 1409 s
1406 w
1316 vs, 1409 s
1407
1333 m, 1407 m
–
1430 s
1409 m
1340 s, 1316 vs
–
150
347
–
303
205
298
183
370 249
205
362 252
189
309 220
–
195
201
328 345
–
287
1607 m, 1528 w 1454 m
1600 m, 1562 w 1467 w
1597 m, 1494 w 1417 m
1596 m, 1550 w
1562 w, 1425 w
1556 w, 1415 w
1587 e, 1478 e
1620 w, 1587 m, 1458 w
1519 w, 1465 m
1558 w, 1510 w
1627 w, 1538 w
–
–
–
–
–
530 w
–
–
–
–
–
487 w
–
497 w
–
527 m
–
534 w
446 m
–
450 m
–
455 m
–
452 w
–
453 m
–
455 m
–
446 w
–
HL9
9
574 w
–
543 w
–
551 w
–
–
–
575 w
–
585 w
–
618 w
–
576 w
HL10
10
H2L11
11
H2L12
12
H2L13
13
–
3417 bw
3443 w
3231 bw
3428 w
–
–
–
1606 s, 1590 s
1575 m, 1459 m
H2L14
14
1604 k, 1584 k 1556 s, 1480 k
1640 m, 1453 w
1617 m, 1559 m 1450 w
1661 s, 1602 m 1584 m, 1466 w
1647 m, 1601 m 1578 m, 1445 w
H2L15
15
–
–
–
–
453 m
–
449 m
H2L16
16
1661 vs
1374 m
Abbreviations: s, strong; m, medium; w, weak; vs, very strong; b, broad.
bands are shifted and some new bands appear. Conse-
quently, only the most important bands in the spectra of
the ligands and their organotin(IV) complexes were
assigned (Tables 6 and 7).
In the spectra of the complexes 1 and 3, the medium and
strong bands of the –NH and –C@O groups characteristic
of the keto tautomer have disappeared, due to the deproto-
nation of the ligands and the binding of the phenolate oxy-
gen(s) to the metal ion. We have been assigned these
frequencies for complexes 4–6 (Table 6). This would imply
that the ligands exist in phenolate and ketone form and
only one of the two OH groups is deprotonated and
bonded to the [Ph3Sn(IV)]+ centre, in accordance with
the analytical results.
The involvement of the aromatic nitrogen {N} in the
coordination can be concluded from the absorption

A. Szorcsik et al. / Journal of Organometallic Chemistry 691 (2006) 1622–1630
1627
frequencies of the mC@N/C@C bands. For 1–3,7, and 8–14
these bands are shifted considerably towards lower fre-
quencies with respect to the positions for the free ligands,
confirming the coordination of the heterocyclic {N} to
the triphenyltin(IV) moiety. The stretching frequency is
lowered owing to the transfer of electron density from
{N} to the {Sn} atom.
tant that there is a –COOꢀ in the ortho position, which is
monodentate and allows the formation of a stable five-
membered chelate ring with the aromatic {N} atom. The
Dm values (220–252 cmꢀ1) of the second –COOꢀ group in
11–13 (Table 7) indicate the bridging anisobidentate coor-
dination mode, which allows the formation of linear
polymeric compounds. Compound 14 may be also long
chain-like polymer, such as above-mentioned complexes.
In this case the oligomerization is occurred through bridg-
ing bidentate –COOꢀ oxygen atoms. Although, the magni-
tude of the Dm predict monodentate coordination mode in
15 and 16, the solubility and the structural elucidation
based on Mo¨ssbauer spectroscopic results showed polymer
structure of the complexes.
The asymmetrical and the symmetrical stretching vibra-
tions of the Sn–C bonds can be used to assign the geometries
of the triorganotin(IV) derivatives [18,19]. In the IR spectra
of 2, 3, 6, 9, 10, 15 and 16 only the masSn–C band can be
observed (Tables 6 and 7), indicating trigonal-planar SnC3
structures (local D3h symmetry). In the case of the other com-
plexes, the occurrence of the msSn–C band showed a signifi-
cant deviation from planarity (local C3v symmetry).
Triorganotin(IV) carboxylates may adopt in principle
three idealised structures (Scheme 3). A Th (A), in which
the –COOꢀ group is monodentately coordinated. In (B),
distorted Tbp with facial organic groups and chelating car-
boxylate group, or a trans Tbp structure in which planar
R3Sn(IV) units are linked by bidentate (C1) or anisobiden-
tate (C2) carboxylate bridges. Additionally, there are more
possibilities in the case of pyridine mono- and dicarboxylic
acids, differing on the ring position of the carboxylic group
(D and E).
For analysis of the IR spectra of the [Ph3Sn(IV)]+–pyr-
idine-carboxylate complexes, there are good approxima-
tions with which to investigate the absorption bands of
the –COOꢀ groups.
The FT-IR spectra of the [Ph3Sn(IV)]+–pyridine-car-
boxylate complexes (Table 7) do not contain the character-
istic bands of the –C@O group of the free ligands. It can
be, therefore, concluded that the [Ph3Sn(IV)]+ moieties
are bound through every carboxylic group of the ligands,
except 14, where the presence of the mC@O band indicate
free CO(OH) group in the complex.
3.3. Mo¨ssbauer spectroscopic results
While the FT-IR data provide valuable information on
the compositions of the adducts, they give no indication
as to their structures. To address this latter question, we
recorded 119Sn Mo¨ssbauer spectra. An unsymmetric dou-
blet with the line width greater than 1.0 mm sꢀ1 was
observed in the spectra of compounds 11–13, suggesting
the presence of Sn in two different coordination environ-
ments. These doublets were deconvoluted into two dou-
blets. The experimental d and |D| parameters determined
by computer evaluation are presented in Table 8. All spec-
tra of the complexes studied display typical |D| values of
central organotin(IV), as well as the characteristic d of
R3Sn(IV) compounds, except 8 (0.88 mm sꢀ1) typical for
R2Sn(IV) moiety.
Deacon shows that the magnitude of the Dm
[Dm = ma(COOꢀ ꢀ ms(COOꢀ)] can be correlated with the
coordination modes of this anion [17]. The Dm values
(Table 7) of the studied complexes (8–16) were compared
with that of the sodium salts of HL8–H2L16 ligands [3].
For complexes 8–10 these Dm values reflect the monoden-
tate coordination mode of the –COOꢀ group, while for
complexes of dicarboxylic acids being indicative of bridg-
ing anisobidentate and monodentate coordination mode,
depending on the location of the two –COOꢀ groups rela-
tive to the ring {N} atom. In complexes 11–14 it is impor-
R'
R
Sn
O
R
R
C
R
O
O
R
R
C
R'
O
O
O
O Sn
Sn
C
R'
C
Sn
O
C
R
R
R
R
R
R
R'
B
C1
A
R
O
O
R'
Sn
R
R
R
R
R
Sn
R
R
R
C
O
Sn
N
O
O
Sn
O
O
Sn
N
C
R
C
R
R
R
R
O
R
R'
C2
E
D
Scheme 3. Structures of the triorganotin(IV) carboxylates.

1628
A. Szorcsik et al. / Journal of Organometallic Chemistry 691 (2006) 1622–1630
Table 8
Experimental and calculated Mo¨ssbauer spectroscopic parameters of complexes studied
d1
|Dexp 1
|
|Dcal 1
|
C1
d2
|Dexp 2
|
|Dcal 2
|
C2
I1:I2
Geom.1
Geom.2
1
2
1.22
1.20
1.21
1.09
1.30
1.16
1.03
0.88
1.23
1.26
1.16
1.25
1.27
1.24
1.24
1.28
2.93
2.89
2.94
1.99
3.30
2.82
1.68
1.92
2.89
3.00
2.82
3.15
3.66
3.54
2.81
3.04
2.86
2.86
2.86
1.97
3.20
2.76
1.55
1.96
3.02
3.02
3.06
3.06
3.06a
3.60
3.06
3.06
1.00
0.98
0.95
0.92
1.02
0.88
0.86
0.90
0.94
1.05
0.87
0.80
1.09
1.16
1.02
0.99
–
–
–
–
–
–
–
–
–
–
0.98
1.02
1.07
–
–
–
–
–
–
–
–
–
–
–
1.71
2.04
2.71
–
–
–
–
–
–
–
–
–
–
–
1.80
1.80
2.70
–
–
–
–
–
–
–
–
–
–
–
1.00
0.80
1.10
–
–
–
–
–
–
–
–
–
–
–
1:1
1:1
1:1
–
Tbp1
Tbp1
Tbp1
Tbp2
Oh1
Tbp3
Tbp4
Oh2
Tbp5
Tbp5
Tbp6
Tbp6
Tbp6
Oh3
–
–
–
–
–
–
–
–
3
4
5
6
7
8
9
–
–
10
11
12
13
14
15
16
Tbp7
Tbp7
Tbp7
–
–
–
–
–
–
–
–
–
–
–
–
–
Tbp6
Tbp6
d, |D| and C are given in mm sꢀ1; Tbp, trigonal-bipyramidal; Oh, octahedral.
a
A distortion of 5–10ꢁ results in the measured |D| value being 0.2–0.6 mmsꢀ1 greater than that calculated for ideal geometry.
On the basis of experimental quadrupole splitting |D|exp
values, the structure of triphenyltin(IV) complexes of HL1–
3 and H2L6 in 1:1 metal to ligand molar ratio are very sim-
ilar. The calculated D values agree very well with the mea-
sured ones (Table 8). These complexes have a distorted Tbp
structure, where the phenyl groups are in eq positions
(Fig. 2). The apical sites are occupied by a {O} of a depro-
tonated hydroxy group and the pyridine {N} and quino-
lone {O} in monohydroxypyridinato complexes and in
the 4-quinolato-2(1H)-quinolone-O,O0 complex, respec-
tively. The O–Sn–X (X = N or O) bond angle is smaller
than 180ꢁ.
Our evaluation of the Mo¨ssbauer spectroscopic mea-
surements by means of the pqs concept, demonstrates that
the coordination geometry of 4 and 7 may be also similar.
On the base of the magnitude of experimental d and |D|
values (d: 1.09, 1.03; |D|: 1.99, 1.68, Table 8), we can rule
out the planar triphenyltin(IV) configuration. The results
of pqs calculations also reveal the formation of distorted
cis Tbp structures, with two phenyl groups in eq and one
in ax position with C–Sn–C bond angles less than 120ꢁ.
The remaining eq site is occupied by the deprotonated
OH group of ligands. In second ax position in the case
of 2,3-dihydroxypyridine there is a pyridone {O} atom
due to the tautomerization (Fig. 1). The protonated {N}
atom is not coordinated. This is in accordance with the
results of the X-ray structural characterisation. In 8-
hydroxyquinoline (oxine) complex the {N} atom is located
in the ax position and five membered chelate ring is formed
(Fig. 3), in correspondence with the published structures of
the investigated triorganotin(IV) complexes of oxin deriva-
tives [20–23].
O-
O-
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Sn O-
Sn Ph
Sn Ph
N
O
O
Tbp1
Tbp2
Tbp3
The Mo¨ssbauer spectrum of Ph3Sn(IV)-4,6-dihydroxy-
pyrimidine complex is a symmetric doublet. According to
the FT-IR measurements both tautomeric forms of the
ligand are co-ordinated and polymeric compound is
formed. The {N} atom does not co-ordinated (Fig. 3).
The d1 and |Dexp|1 values for the pyridine carboxylic acid
complexes fall in the range 1.16–1.28 and 2.81–
3.66 mm sꢀ1, except 2-picolinic acid with unexpected low
values (0.88 and 1.92 mm sꢀ1). We were obtained 8 as sin-
gle crystals. The preliminary X-ray diffraction investigation
showed that in this case there is a [Ph2Sn(IV)]2+ complex
formed. The molecular structure of the 8 is already known
[6]. The isomer shift of Ph2Sn(L8)2 is in the range typical of
diorganotin(IV) derivatives [10]; |Dexp| is consistent with
that of hexa-coordinated diorganotin(IV) complexes in
highly distorted cis-Oh geometry with the two bulky phenyl
groups in ax and eq positions [5] (Fig. 2). The –COOꢀ
-OOCm
OCOa
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
Ph
-
Sn O-
Sn Ph
OCOa
Sn Ph
N
Sn OOCm
N
N
Tbp6
Tbp7
Tbp4
Tbp5
O-
-OOCm
Ph
Ph
Ph
Ph
Ph
Ph
N
bOCO
N
Ph
Sn
Sn
Sn
Ph
-
OH2
OOCm
OCOb
O
N
Oh1
Oh2
Oh3
Fig. 2. Calculated quadrupole splitting values for the tin(IV) coordination
spheres in different stereochemical arrangements. m, monodentate coor-
dination mode; b, bidentate coordination mode; a, anisobidentate
coordination mode.

A. Szorcsik et al. / Journal of Organometallic Chemistry 691 (2006) 1622–1630
1629
Ph
Sn
Ph
Sn
Ph
Ph
Sn
O
O
Ph
O
Ph
O
N
O
N
Sn
H2O
O
Ph
Ph
Ph
Ph
Ph
Ph
n
OH2
HN
N
n
a
Ph
Ph
Sn
N
O
Ph
O
b
Ph
Ph
O
Sn
N
C
O
N
C
O
Ph
Sn
O
d
Ph
O
c
O
Ph
Ph
O
Ph
C
O
Ph
O
Ph
Sn
Ph
Sn
Ph
Ph
Sn
Ph
O
PH
N
Ph
Ph
O
Ph
Sn
C
O
N
C
Ph
O
O
O
Sn
Ph
C
Ph
Ph
Ph
Ph
Sn
C
O
N
O
Ph
O
Ph
Ph
O
Sn
Ph
C
Ph
O
Sn
f
O
Ph
e
Fig. 3. Proposed structures for some selected complexes; a, b, e and f – repeating units of 3, 5, 12 and 16, respectively, c and d – monomeric complexes
of 7 and 8.
groups of the two picolinate anions are unidentate, and
therefore form with the hetero cyclic {N} atom five mem-
bered O–C–Sn–C–N chelate ring. Our results further con-
firm the published structure.
ings. For H2L11–14, it is important to note that there is a –
COOꢀ group in the ortho position (relative to the ring {N}
atom), which allows the formation of a stable five-mem-
bered chelate ring. The Mo¨ssbauer spectra of the
[Ph3Sn(IV)]+ complexes of H2L11–13 display two unsym-
metrical doublets, indicating the presence of two different
Sn(IV) environments within the complexes. Deconvulation
of the spectra for the three cases resulted in one of the dou-
blet with d1 and |Dexp|1 values (Table 8) characteristic of a
trans Tbp and a second doublet with d2 and |Dexp|2 values
(Table 8) characteristic of a cis Tbp Sn(IV) environment
(Fig. 2). In the trans Tbp species the phenyl groups are
located in eq positions and linear polymerisation is
occurred through the bridging anisobidentate –COOꢀ
groups in ax positions. The pqs calculations lead to the
finding, that the latter Sn(IV) moiety, with cis Tbp symme-
try, involves two phenyl groups in eq and one in ax posi-
tions. The monodentately bounded carboxylate oxygen
and the pyridine nitrogen formed five-membered chelate
ring with the {Sn} centre (Fig. 3) The FT-IR measurements
revealed the two type carboxylate coordination mode in
these complexes, which is consistent with the conclusion
from Mo¨ssbauer data.
Ph3Sn(IV)-2,6-pyridine-dicarboxylato complex repre-
sents a more interesting case. The Mo¨ssbauer spectrum
exhibits only one symmetric, unbroadened doublet, indi-
cating only one type of environment around tin(IV) in
the complex, with |Dexp| value of 3.54 mmsꢀ1. When the
calculated quadrupole splitting values, based on different
suggested stereochemistries of the tin(IV) surrounding were
compared with the experimental one we got a good agree-
ment with that suggesting an Oh symmetry of Ph3Sn(IV)-
2,6-pyridine-dicarboxylate involving ax and one eq phenyl
It is known, that in sea water the biologically active sed-
iments convert trimethyltin(IV) hydroxyde to dimethyltin
compound and to the volatile tetramethyltin(IV) [24].
The methyl group removal has been attributed to the
action of UV light, chemical cleavage and biological degra-
dation by bacteria, although its chemistry has never been
elucidated. In our case a similar, phenyl migrational dismu-
tation has been detected in methanolic solution of
Ph3SnOH–2-picolinic acid system according to the results
of X-ray and Mo¨ssbauer spectroscopic measurements.
For this reaction we propose the following mechanism:
Ph3SnOH þ HL8 ¼ Ph3SnL8 þ H2O
2Ph3SnL8 ¼ Ph2SnðL8Þ þ Ph4Sn
2
This reaction is interesting because, to our knowledge, it
is the first report of a Lewis base-induced redistribution of
a triphenyltin(IV) compound.
In the [Ph3Sn(IV)]+ complexes of nicotinic and isonicot-
inic acids, a five-membered chelate ring formation as
shown above, is not possible. The structural elucidation
based on pqs concept has shown, that linear oligomeriza-
tion is occurred through the monodentate –COOꢀ group
and through the {N} atom from two different ligands. In
complexes, the Sn centres are in distorted trans Tbp coor-
dination geometry with phenyl groups in the equatorial
positions (Fig. 2).
For the pyridine-dicarboxylic acid complexes, it is obvi-
ous that the two –COOꢀ groups are in different surround-

1630
A. Szorcsik et al. / Journal of Organometallic Chemistry 691 (2006) 1622–1630
groups, with two bidentate carboxylate oxygens and pyri-
dine nitrogen in the remaining eq positions (Fig. 2). Six-
coordination is indicated also by IR spectra. The mC@O
absorption at 1692 cmꢀ1 indicate that one of the two car-
boxylate groups remained free and involved in hydrogen
with the Cambridge Crystallographic Data Center as sup-
plementary publication No. CCDC 286848. Copies of the
data can be obtained free of charge on application to
CCDC, 12 Union Road, Cambridge CB2 1EZ, UK [Fax:
int. code +44 1223 336-033; E-mail: deposit@ccdc.
cam.ac.uk].
bonding system, while the DmCOOꢀ value (195 cmꢀ1
)
reveal bidentate mode for the second one.
The Mo¨ssbauer spectra of the [Ph3Sn(IV)]+ complexes
formed with pyridine-3,4- and -3,5-dicarboxylic acids exhi-
bit only one symmetrical doublet. The identical Mo¨ssbauer
parameters of these two compounds suggest that the sym-
metry of the coordination sphere of the Sn(IV) is very sim-
ilar. It can be seen that the experimental |Dexp| values of
these compounds are close to that calculated for the ideal
trans Tbp geometry (Figs. 2 and 3). Moreover, both the
m.p. data and the low solubility of 15 and 16 suggest a
long-chain polymeric structure of these compounds. There
has been some disagreement concerning the magnitude of
the Dm values and the suggested structure. This can be elu-
cidate by assumption, that the bounding of the –COOꢀ
groups is alternate between mono- and bidentate mode.
Therefore, the oligomerization between tin(IV) centres is
interpreted through anisobidentate –COOꢀ groups of
ligands.
Acknowledgements
This work was supported financially by the Hungarian
Research Foundation (OTKA T043551) and by the Minis-
tero dell’Istruzione, dell’Universita
(M.I.U.R, CIP 2004059078_003), by the Universita di
Palermo (ORPA 41443), Italy.
´
e
della Ricerca
`
References
[1] L. Pellerito, L. Nagy, Coord. Chem. Rev. 224 (2002) 111.
[2] Y. Nath, S. Pokharia, R. Yadav, Coord. Chem. Rev. 215 (2001) 99.
[3] A. Szorcsik, L. Nagy, J. Sletten, G. Szalonati, E. Kamu, T. Fiore, L.
´
´
Pellerito, E. Kalman, J. Organomet. Chem. 689 (2004) 1145, and
references therein.
´
´
[4] A. Szorcsik, L. Nagy, A. Deak, M. Scopelliti, Z.A. Fekete, A.
´
´
Csaszar, C. Pellerito, L. Pellerito, J. Organomet. Chem. 689 (2004)
2762, and references therein.
´
[5] A. Szorcsik, L. Nagy, M. Scopelliti, A. Deak, L. Pellerito, K.
Hegetschweiler, J. Organomet. Chem. 690 (2005) 2280.
[6] M. Gielen, M. Acheddad, B. Mahieu, R. Willem, Main Group Met.
Chem. 14 (1991) 73.
4. Conclusions
The synthetic procedures used in this work resulted in
the formation of [Ph3Sn(IV)]+ compounds with a 1:1
metal-to-ligand ratio for ligands containing a hetero {N}
atom and a hydroxy group, for nicotinic, isonicotinic and
dipicolinic acid, while for the pyridine dicarboxylic acid
complexes 2:1. The X-ray diffraction analysis of complex
4 shows a distorted cis Tbp coordination sphere around
the Sn(IV) center. In methanolic Ph3SnOH 2-picolinic acid
system, we have observed a phenyl migrational dismuta-
tion reaction, which resulted Ph2Sn(pica)2 and Ph4Sn.
The analytical, FT-IR and Mo¨ssbauer spectroscopic data
of these complexes revealed the formation of well-defined
compounds. The Mo¨ssbauer spectroscopic data for
complexes 1–3, 6, 9–13, 15 and 16 are indicative of trigo-
nal-planar SnC3 (i.e. trans Tbp) structures with the phenyl
groups in eq positions. The Mo¨ssbauer spectra of the
[Ph3Sn(IV)]+ complexes of H2L11–13 display two unsym-
metrical doublets, indicating the presence two different
(trans and cis Tbp) Sn(IV) environments in the complexes.
In polymeric complexes the linear oligomerisation is
occurred through the bridging anisobidentate –COOꢀ
groups in ax positions.
[7] S.W. Ng, C. Wei, V.G.K. Das, J. Van Meura, J.D. Schagen, L.H.
Straver, Acta Cryst. C45 (1989) 570.
[8] S.W. Ng, C. Wei, V.G.K. Das, J. Cryst. Struct. Res. 22 (1992)
371.
[9] G.M. Sheldrick, SHELXS97-Program for Crystal Structure Determina-
tion and SHELXL97-Program for the Refinement of Crystal Structures,
Universita¨t Go¨ttingen, Germany, 1997.
[10] G.M. Bancroft, R.H. Platt, Adv. Inorg. Chem. Radiochem. 15 (1972)
59.
[11] G.M. Bancroft, V.G. Kumar Das, T.K. Sham, M.G. Clark, J. Chem.
Soc. Dalton Trans. (1976) 643.
[12] L. Pellerito, F. Maggio, T. Fiore, A. Pellerito, Appl. Organomet.
Chem. 10 (1996) 393.
[13] H.I. Abdulla, M.F. El-Bermani, Spectrochim. Acta A 57 (2001)
2659.
´
[14] G.A. Carriedo, P.G. Elipe, F.J.G. Alonso, L. Fernandez-Catuxo,
´
M.R. Dıaz, S.G. Granda, J. Organomet. Chem. 498 (1995) 207.
[15] S. Wang, Polyhedron 17 (1998) 831.
[16] S. Maity, R. Roy, C. Sinha, W.-J. Sheen, K. Panneerselvam, T.-H.
Lu, J. Organomet. Chem. 650 (2002) 202.
[17] G.B. Deacon, R.J. Philips, Coord. Chem. Rev. 33 (1980) 227.
[18] R.C. Poller, The Chemitry of Organotin Compounds, Logos Press,
London, 1970.
[19] D. Cunningham, L.A. Kelly, K.C. Molloy, J.J. Zuckerman, Inorg.
Chem. 21 (1982) 1416.
[20] R.C. Poller, J.N.R. Ruddick, J. Organomet. Chem. 39 (1972) 121.
[21] T.K. Sham, G.M. Bancroft, Inorg. Chem. 14 (1975) 2281.
[22] P.G. Harrison, R.C. Phillips, J. Organomet. Chem. 99 (1975)
79.
5. Supplementary material
[23] V.G. Kumar Das, S.W. Ng, P.J. Smith, Inorg. Chim. Acta 49 (1981)
149.
[24] H.E. Guard, A.B. Cobet, W.M. Coleman III, Science 213 (1981) 770.
Crystallographic data (excluding structure factors) for
the structure reported in this paper have been deposited