The synthesis and structural characterization of some triorganotin(IV) complexes of 2-{[(E)-1-(2-hydroxyaryl)alkylidene]amino} acetic acid. Crystal and molecular structures of Ph3Sn(2-OHC6H4C(H)=NCH2COO) and Me3Sn(2-OHC6H4C(CH3)=NCH2COO)

Article abstract of DOI:10.1016/S0022-328X(02)01387-6

Triorganotin(IV) derivatives of 2-{[(E)-1-(2-hydroxyaryl)alkylidene]amino} acetic acid have been synthesized and characterized by (1)H, (13)C, (119)Sn-NMR, (119)Sn Moessbauer and IR spectroscopic techniques in combination with elemental analyses. The crystal structures of triphenyltin 2-{[(E)-1-(2-hydroxyphenyl)methylidene]amino} acetate and trimethyltin 2-{[(E)-1-(2-hydroxyphenyl)ethylidene]amino}acetate are reported. The X-ray structures reveal That the complexes adopt a polymeric trans-O2SnC3 trigonal bipyramidal configuration with the R groups in the equatorial positions and the axial locations occupied by a carboxylate oxygen from the ligand and the phenolic oxygen of the ligand on an adjacent complex. The ligands coordinate in the zwitterionic form with the phenolic proton moved to the nearby nitrogen atom. There is hydrogen bonding between this proton and the phenolic oxygen. The carboxylate group is unidentate. The spectroscopic evidence in combination with (119)Sn Moessbauer data suggest that the other complexes adopt similar polymeric structures in the solid state.

Full text of DOI:10.1016/S0022-328X(02)01387-6

Journal of Organometallic Chemistry 654 (2002) 100ꢀ108
/
www.elsevier.com/locate/jorganchem
The synthesis and structural characterization of some
triorganotin(IV) complexes of 2-{[(E)-1-(2-
hydroxyaryl)alkylidene]amino}acetic acid. Crystal and molecular
structures of Ph3Sn(2-OHC6H4C(H)ꢀ
/
NCH2COO) and Me3Sn(2-
OHC6H4C(CH3)ꢀNCH2COO)
/
Tushar S. Basu Baul a,*, Sushmita Dutta a, Eleonora Rivarola b, Ray Butcher c, Frank
E. Smith d,*
a Department of Chemistry, North-Eastern Hill University, Permanent Campus Mawlai, Shillong 793 022, India
b Dipartimento di Chimica Inorganica, Universita di Palermo, Parco d’Orleans II Viale delle Scienze, Palermo 90128, Italy
c Department of Chemistry, Howard University, Washington, DC 20059, USA
d Department of Chemistry and Biochemistry, Laurentian University, Sudbury, Ont., Canada P3E 2C6
Abstract
Triorganotin(IV) derivatives of 2-{[(E)-1-(2-hydroxyaryl)alkylidene]amino}acetic acid have been synthesized and characterized
1
by H, 13C, 119Sn-NMR, 119Sn Mossbauer and IR spectroscopic techniques in combination with elemental analyses. The crystal
¨
structures of triphenyltin 2-{[(E)-1-(2-hydroxyphenyl)methylidene]amino}acetate and trimethyltin 2-{[(E)-1-(2-hydroxypheny-
l)ethylidene]amino}acetate are reported. The X-ray structures reveal that the complexes adopt a polymeric trans-O2SnC3 trigonal
bipyramidal configuration with the R groups in the equatorial positions and the axial locations occupied by a carboxylate oxygen
from the ligand and the phenolic oxygen of the ligand on an adjacent complex. The ligands coordinate in the zwitterionic form with
the phenolic proton moved to the nearby nitrogen atom. There is hydrogen bonding between this proton and the phenolic oxygen.
The carboxylate group is unidentate. The spectroscopic evidence in combination with 119Sn Mossbauer data suggest that the other
¨
complexes adopt similar polymeric structures in the solid state. # 2002 Published by Elsevier Science B.V.
Keywords: Organotin; Carboxylates; 2-{[(E)-1-(2-hydroxyaryl)alkylidene]amino}acetic acid; NMR; Mossbauer; X-ray
¨
1. Introduction
compounds with the monomeric cis-R3SnO2 structural
type [3,5]. However, two types of bridging are known for
the trans-R3SnO2 configuration of organotin carboxy-
lates. The most commonly encountered structure is
polymeric in which the carboxylate groups behave as
bridging bidentate ligands and the pentacoordinated tin
atoms have distorted trigonal bipyramidal geometries.
Alternatives to carboxylate bridging for the trans-
R3SnO2 structural moiety have been reported for
triorganotin carboxylates containing either donor sub-
stituent groups [6,7] or a labile phenolic group in the
ester function [8]. Consequently, in recent years there
has been an upsurge in the synthesis of organotin
carboxylates of substituted benzoic acids. These studies
have revealed new structural possibilities [9] and, more
recently, certain derivatives have been demonstrated to
Organotin carboxylates have a variety of biocidal
activities [1ꢀ
structural variations [4] which have led to the proposal
of some structureꢀactivity relationships [5]. The
structureꢀactivity relationship studies suggest that trior-
/
3] along with an interesting range of
/
/
ganotin carboxylates with either an isolated tetrahedral
tin center or a trans-R3SnO2 geometry around the tin
atom show significantly greater biocidal activity than
* Corresponding authors. Tel.: ꢁ
/
91-364-227283; fax: ꢁ
/
91-364-
228213 (T.S.B.B.); tel.:
(F.E.S.).
ꢁ
/
1-705-675-1151; fax: 1-705-675-4844
ꢁ
/
E-mail addresses: basubaul@hotmail.com (T.S. Basu Baul),
fsmith@nickel.laurentian.ca (F.E. Smith).
0022-328X/02/$ - see front matter # 2002 Published by Elsevier Science B.V.
PII: S 0 0 2 2 - 3 2 8 X ( 0 2 ) 0 1 3 8 7 - 6

T.S. Basu Baul et al. / Journal of Organometallic Chemistry 654 (2002) 100ꢀ
/108
101
possess exciting cytotoxic activity [10]. We have recently
reported the coordination behavior of 2-{[(E)-1-(2-
hydroxyaryl)alkylidene]amino}acetic acid towards the
R2Sn(IV) moiety [11,12]. Moreover, these diorganotin
complexes were used as coordinating ligands to form
uncommon mixed dinuclear organotin species in which
the two tin atoms are connected via the carbonyl atom
of the ligand [11].
As a continuation of our studies on such interesting
systems, we now report the synthesis and characteriza-
tion of a series of new triorganotin(IV) complexes
derived from sodium or potassium 2-{[(E)-1-(2-hydro-
xyaryl)alkylidene]amino}acetate (LHM, Fig. 1).
on a PerkinꢀElmer 983 spectrophotometer with samples
/
investigated as KBr discs. The H, 13C and 119Sn-NMR
spectra were acquired on a Bruker ACF 300 spectro-
meter and measured at 300.13, 75.47 and 111.92 MHz,
respectively. The 1H, 13C spectra were referenced to
Me4Si while 119Sn chemical shifts were referenced to
1
Me4Sn, all set at 0.00 ppm. 119Sn Mossbauer spectra of
¨
the complexes in the solid state were obtained at liquid-
nitrogen temperature on a conventional constant accel-
eration spectrometer equipped with a CRYO cryostat
and a 119Sn Mossbauer source. The velocity calibration
¨
was made using a 57Co Mossbauer source, and an iron
¨
foil enriched to 95% in 57Fe (DuPont Pharma Italia,
Firenze, Italy) was used as the absorber. The
Ca119mSnO3 and 57Co sources, 10 mCi, were procured
from Ritverc, St. Petersburg, Russia.
2. Experimental
2.1. Materials
2.3. X-ray crystallography
Me3SnCl (Merck), Bu3SnCl (Merck) and Ph3SnCl
(Fluka AG) were used without further purification.
Glycine (Aldrich), 2-hydroxyacetophenone (Aldrich), 2-
hydroxybenzaldehyde (Fluka), 2-hydroxy-5-chloroben-
zaldehyde (Kodak) were of reagent grade whereas 2-
The intensity data for yellow blocked shaped crystals
of complexes 2 and 4 were measured at 293 K on a
Rigaku AFC6S diffractometer fitted with graphite
˚
Ka radiation (lꢃ0.71073 A)
monochromatized Moꢀ
/
/
using the omega scan technique. Empirical corrections
were made from psi-scan curves [13]. The structures
were solved by direct methods. All hydrogen atoms were
given calculated positions. Neutral atom scattering
factors were taken from the literature [14]. All computa-
tions were performed using the TEXSAN system of crystal
structure solving programmes [15]. All refinements were
performed by full-matrix least-squares on F2. The data
were corrected for Lorentz and polarization effects.
hydroxy-5-methylacetophenone
and
2-hydroxy-3-
methylacetophenone were gift samples. All the solvents
used in the reactions were of AR grade and dried using
standard literature procedures.
2.2. Physical measurements
Carbon, hydrogen and nitrogen analyses were per-
formed with a Perkinꢀ
IR spectra in the range 4000ꢀ
/
Elmer 2400 series II instrument.
400 cmꢂ1 were obtained
/
2.4. Preparation of sodium and potassium salts of 2-
{[(E)-1-(2-hydroxyaryl)alkylidene]amino}acetate
The sodium (L3HNa and L5HNa) or potassium
(L2HK, L3HK and L5HK) salts of 2-{[(E)-1-(2-hydro-
xyaryl)alkylidene]amino}acetic acid were prepared by
reacting equimolar amounts of sodium or potassium
glycinate with either 2-hydroxyacetophenone or 2-hy-
droxybenzaldehyde [11], as appropriate, while L1HK
and L4HK were prepared under cold conditions (ꢂ
/
10 8C) according to the reported procedure [16]. The
salts of the ligands were recrystallized from methanol
and obtained in ꢀ60% yield as yellow crystalline solids.
/
The characterization data for L1HK, L2HK, L4HK,
L5HK and L5HNa are recorded in Tables 1 and 4 while
for L3HK and L3HNa are reported in [11].
2.5. Synthesis of the triorganotin complexes
Fig. 1. Ligands used in the present work.
Three typical methods are described below.

102
T.S. Basu Baul et al. / Journal of Organometallic Chemistry 654 (2002) 100ꢀ108
/
Table 1
Synthetic and analytical data for the triorganotin(IV) complexes
f
Complex
Reaction time (h) Crystallization solvent
Color
Yield (%) M.p. (8C)
Elemental analysis Found (Calc.) (%)
C
H
N
a
Bu3SnL1 H (1)
Ph3SnL1 H (2)
Ph3SnL2 H (3)
Me3SnL3 H (4)
Bu3SnL3 H (5)
Ph3SnL3 H (6)
Me3SnL4 H (7)
Ph3SnL4 H (8)
Bu3SnL5 H (9)
Ph3SnL5 H (10)
1
3
2
3
7
3
5
2
3
2
Chloroform
Chloroform
Chloroform
Methanol
Yellow
Yellow
Yellow
Yellow
70
71
42
70
50
Viscous liquid 54.15 (53.99) 7.26 (7.33) 3.09 (2.99)
b
c
156ꢀ
146ꢀ
188ꢀ
110ꢀ
190ꢀ
150ꢀ
127ꢀ
122ꢀ
182ꢀ
/
57
48
90
12
92
52
28
24
84
61.20 (61.40) 4.35 (4.39) 2.68 (2.65)
57.50 (57.64) 3.83 (3.94) 2.60 (2.48)
43.90 (43.86) 5.38 (5.38) 4.15 (3.93)
54.39 (54.79) 7.80 (7.73) 2.84 (2.90)
61.85 (62.03) 4.35 (4.64) 2.61 (2.58)
45.40 (45.44) 5.70 (5.72) 3.80 (3.78)
62.68 (62.60) 4.93 (4.89) 2.48 (2.51)
55.85 (55.67) 7.90 (7.92) 2.98 (2.82)
62.48 (62.62) 4.87 (4.89) 2.37 (2.51)
/
d
e
/
Chloroformꢁpetroleum ether Yellow
Chloroformꢁpetroleum ether Pale yellow 65
Chloroform
Chloroform
Chloroform
Chloroform
/
d
c
/
Yellow
Yellow
Yellow
Yellow
17
40
74
60
/
c
/
a
c
/
/
a
Method: stirring in chloroform.
b
c
d
e
f
Method: reflux in methanolꢀbenzene mixture (1:1).
/
Method: stirring in methanol.
Method: reflux in methanol.
Method: reflux in benzene.
The decomposition points of the Kꢀ
/
Na-salts of the corresponding ligands are 216ꢀ
218 8C (L1HK), ꢀ250 8C (L2HK), 205 8C (L4HK),
/
259 8C (L5HK) and 214 8C (L5HNa).
2.5.1. Ph3SnL1H (2)
h. The reaction mixture was filtered while hot and the
filtrate was evaporated to dryness. The yellow jelly-like
residue was cooled in a freezing mixture and then
petroleum ether was added drop wise to yield a crude
product. This was washed thoroughly with petroleum
ether and finally recrystallized from chloroform and
petroleum ether (1:1 v/v).
Ph3SnCl (1.77 g, 4.60 mmol) in benzene (25 ml) was
added dropwise with continuous stirring to L1HK (1.0
g, 4.60 mmol) in 50 ml methanol. The reaction was then
refluxed for 3 h and the solvent was distilled off to
dryness using a rotary evaporator. The residue was
washed with petroleum ether, extracted into hot chloro-
form and filtered. The yellow-colored extract was
distilled off (up to 50% of the initial solvent volume)
and kept at room temperature (r.t.) for crystallization.
On the following day, the solid was isolated by filtration
and recrystallized from methanol and chloroform mix-
ture. Slow evaporation of methanol and chloroform
solutions (1:1 v/v) of the product deposited shining
block-like crystals suitable for structural studies.
3. Results and discussion
3.1. Syntheses
Triorganotin(IV) complexes of 2-{[(E)-1-(2-hydro-
xyaryl)alkylidene]amino}acetic acid can be prepared in
moderate yield by allowing stoichiometric amounts of
R3SnCl and sodium or potassium 2-{[(E)-1-(2-hydro-
xyaryl)alkylidene]amino}acetate to react in chloroform,
benzene, methanol or a combination of these solvents as
shown in equation (1):
2.5.2. Me3SnL3H (4)
Me3SnCl (0.80 g, 4.01 mmol) in methanol (30 ml) was
added dropwise with continuous stirring to a hot
methanol solution (50 ml) containing either L3HNa
(0.863 g, 4.01 mmol) or L3HK (0.927 g, 4.01 mmol). The
reaction mixture was heated at reflux temperature for 3
h and then the solvent was removed using a rotary
evaporator. The yellow mass was washed thoroughly
with hot petroleum ether, extracted into chloroform and
filtered. The yellow product obtained upon concentra-
tion of the chloroform extract was recrystallized from
methanol which upon slow evaporation yielded yellow
block crystals suitable for structural studies.
LHMꢁR3SnCl 0 R3SnLHꢁMCl
(LHM as described in Fig. 1 and Rꢃ
(1)
/
Me, Bu or Ph).
The exact synthetic methodology and reaction condi-
tions for each of the complexes are reported in Table 1
along with their characterization data. In general, the
solubility for the triphenyltin compounds was found to
be very poor, even in hot chloroform. A large amount of
chloroform was needed to extract the pure triphenyltin
compounds, however, the other triorganotin com-
pounds were readily extracted. Attempts to prepare
the triorganotin complexes by the reaction of (R3Sn)2O
with glycine and the appropriate salicylaldehyde or
2.5.3. Bu3SnL3H (5)
The compound was prepared by reacting Bu3SnCl
(0.64 g, 1.96 mmol) and L3HK (0.454 g, 1.96 mmol) in
anhydrous benzene (50 ml) under reflux conditions for 7

Table 2
1H chemical shifts (d, ppm) for the triorganotin(IV) complexes
a
Complex
Ligand skeletonb
SnꢁR skeletonc
H-2
H-5
H-6
H-7
H-8
H-9
H-3?
H-6?
H-8?
1*
2*
3*
4*
1
2
4.35, s
4.32, s
4.47, s
4.19, s
4.35, s
3.21, s
4.32, s
4.44, s
4.34, s
4.12, s
16.2, brs
13.2, brs
13.2, brs
Nd
6.85, d
6.87, d
6.91, d
6.89, d
6.92, d
5.76, d
7.29, t
7.26, t
7.20, d
7.44, t
7.26, t
6.29, t
7.17, d
7.18, d
7.08, d
7.02, d
6.77, t
6.81, t
6.94, d
7.18, d
7.23, s
7.75, d
7.50, d
6.56, d
7.37, d
7.40, d
7.29, s
7.28, s
8.34, s
8.22, s
8.26, s
2.63, s
2.30, s
1.19, s
2.31, s
2.29, s
2.28, s
2.20, s
ꢀ
ꢀ/
ꢀ/
ꢀ/
ꢀ/
ꢀ/
/
ꢀ
ꢀ/
ꢀ/
ꢀ/
ꢀ/
ꢀ/
ꢀ/
ꢀ/
/
1.26, m
1.26, m
7.72, m
7.72, m
1.59, m
7.42, m
7.46, m
0.90, t
7.42, m
7.46, m
ꢀ/
ꢀ/
3
ꢀ/
4
6.87, t
6.75, t
5.71, t
6.66, t
6.68, t
0.42, s (63)
1.32, m
ꢀ/
ꢀ/
ꢀ/
5
16.1, brs
15.6, brs
16.5, brs
16.2, brs
16.2, brs
16.1, brs
1.32, m
6.85, m
1.62, m
6.41, m
0.95, t
6.41, m
6
ꢀ/
7
ꢀ/
ꢀ/
2.26, s
2.24, s
0.58, s(59)
ꢀ/
ꢀ/
ꢀ/
8
ꢀ/
7.77, m
1.32, m
7.78, m
7.45, m
1.62, m
7.36, m
7.45, m
0.91, t
7.36, m
9
10
6.84, d
6.62, d
ꢀ/
ꢀ/
ꢀ/
ꢀ/
2.27, s
2.10, s
1.32, m
ꢀ/
n.d., Not detected.
a
b
c
Solvents: Saturated DMSO-d6 solutions were used for complexes 4 and 6 while others were in CDCl3.
Refer to Fig. 1 for numbering scheme.
Numbering scheme for SnꢁR skeleton as shown below:
.

Table 3
a
b
13C and 119Sn chemical shifts (d, ppm) for the triorganotin(IV) complexes
Complex
Ligand skeleton
SnꢁR skeleton
119Sn-NMR
C-1
C-2
C-3
C-4
C-5
C-6
C-7
C-8
C-9
C-3?
C-6?
C-8?
1*
2*
3*
4*
1
2
173.9
174.9
174.6
170.6
173.8
171.4
173.9
175.1
174.1
173.0
60.5
167.5
167.7
166.7
170.0
172.7
169.5
172.8
165.1
172.6
171.8
118.7
119.8
119.4
116.8
119.4
116.6
118.4
118.6
125.9
124.7
161.3
161.3
159.8
163.3
163.7
163.5
162.4
161.7
161.2
162.3
117.1
118.5
118.7
116.9
118.7
117.0
127.6
117.4
119.2
118.5
132.4
133.7
132.4
130.6
136.4
130.8
133.3
133.3
133.4
133.7
118.4
117.1
131.6
131.6
130.6
126.6
128.0
126.7
125.7
125.7
128.1
130.9
ꢀ
ꢀ/
/
ꢀ
ꢀ/
ꢀ/
ꢀ/
ꢀ/
ꢀ/
15.1
15.1
/
ꢀ
ꢀ/
ꢀ/
ꢀ/
ꢀ/
ꢀ/
ꢀ/
ꢀ/
/
16.6
136.9
137.3
ꢂ1.71
16.6
27.8
136.6
136.8
27.1
128.8
129.0
13.7
132.6
130.4
126.8
b
59.8
59.7
49.9
51.6
49.9
51.5
51.4
51.8
52.2
b
3
ꢀ/
-
4
114.1
116.9
114.1
116.2
116.4
118.4
117.6
12.8
14.8
12.7
16.1
16.0
14.9
14.7
ꢀ/
27.7
134.4
ꢀ/
26.9
126.3
ꢀ/
13.6
126.9
134.5
121.9
5
6
141.2
ꢂ1.95
137.6
16.7
ꢂ95.8
134.7
7
ꢀ/
136.9
27.8
ꢀ/
128.9
27.1
ꢀ/
130.3
13.7
8
ꢂ95.8
123.9
9
10
ꢀ/
ꢀ/
20.7
20.4
b
137.3
136.4
127.9
128.3
Refer to Fig. 1 and Table 2 for numbering scheme of the ligand and SnꢁR skeletons, respectively; coupling constants, n J(13Cꢁ117/119Sn) (Hz): for trimethyltin complexes 4 and 7 1Jꢃ258 and 200;
for tributyltin complexes: 2Jꢃ21, 3Jꢃ65 whereas 1J and 4J could not be detected; for triphenyltin complexes: 2Jꢃ50, 3Jꢃ64 whereas 1J and 4J could not be detected.
a
b
Not recorded due to solubility problem.

T.S. Basu Baul et al. / Journal of Organometallic Chemistry 654 (2002) 100ꢀ
/108
105
hydroxyacetophenone invariably resulted a complex
mixture which could not be separated.
complexes exhibit a single sharp resonance at around
134 ppm for RꢃMe; 4 and 7; between 121.9 and 126.8
for RꢃBu; 1, 5 and 9, and at around ꢂ95.8 ppm for
RꢃPh; 6 and 8. These are consistent with the range
expected for tetrahedral triorganotin compounds
[17,19]. Thus, 119Sn-NMR results indicate that the
five-coordinated polymeric structure of solids (as re-
/
/
/
/
3.2. NMR data
The 1H and 13C-NMR data of the triorganotin
complexes are shown in Tables 2 and 3, respectively.
The 1H and 13C chemical shift assignments of the
triorganotin moiety is straightforward from the multi-
plicity patterns and/or resonance intensities [17] whereas
the ligand skeletons were assigned by the multiplicity
patterns and/or resonance intensities of the signals and
also by the standard distortionless enhancement by
polarization transfer (DEPT) experiments [11], wherever
required. The efforts to use the NMR data in the
elucidation of the coordination mode of the ligand and
the geometries of the complexes were not successful
since (i) it was not possible to isolate the free acid,
making comparisons with it difficult, and (ii) the
solvents used for the spectra (DMSO-d6 in some cases)
were not all the same and this could influence the nature
of the coordination sphere.
vealed by X-ray and Mossbauer, vide infra) is lost upon
¨
dissolution giving rise to four-coordinate monomeric
structures in solution.
3.3. IR data
The solid-state IR spectra of the complexes (Table 4)
all display a band near 1650 cmꢂ1 which is assigned to
the n(OCO)asym vibration. In the sodium and potassium
2-{[(E)-1-(2-hydroxyaryl)alkylidene]amino}acetate, this
vibration appears at 1618 and 1628 cmꢂ1, respectively.
The shift of this n(OCO)asym band to higher wave
number in the complexes is reported to be diagnostic
of bonding between the carbonyl oxygen atom of the
ligand and the triorganotin group [11]. Absorption
bands believed due to the n(OCO)sym stretch have
None of the triorganotin complexes exhibit
1J(13Cꢁ
/
119/117Sn) coupling satellites in solution owing
been assigned since the magnitude of the n(OCO)asym
ꢀ
/
to the solubility problem. The 13C chemical shift of the
ipso-carbon of the SnPh3 moiety is around 138 ppm in
CDCl3 solution which is typical for a tetrahedral tin
atom [18]. Five-coordinated triphenyltin carboxylates
have a value ca. 4 ppm higher in frequency such as is
found for complex 6 in DMSO-d6 solution.
n(OCO)sym (i.e. Dn) separation is of interest. The
observed values of Dn, which are in the range 281ꢀ
/
327
cmꢂ1, indicate a unidentate bonding mode for the
carboxylate moiety [8]. For a bridging or chelating
carboxylate group, Dn would be expected to be B
/
150
cmꢂ1 [20], as widely observed in the infrared spectra of
triorganotin carboxylates [21]. This suggests that the
phenolic group occupies the fifth coordination site at the
tin atom [22]. This is further substantiated by the broad
In recording 119Sn-NMR spectra of organotin(IV)
complexes in solution, non-coordinating solvents are
preferable to coordinating ones to preclude possible
changes in the coordination number of the tin atom. In
the present investigation, a few complexes were found to
be suitable for recording 119Sn-NMR spectra in CDCl3
solution. These are listed in Table 3. The organotin
IR absorptions in the region 3600ꢀ
3400 cmꢂ1 which are
/
reported to be due to intramolecular hydrogen bonding
between the phenolic proton and the azomethine nitro-
gen [23]. Such intramolecular hydrogen bonding would
Table 4
IR data (cmꢂ1) for the ligands and triorganotin(IV) complexes
Complex
n(OCO)asym
n(OCO)sym
Dn
n(Phꢁ(CO))
n(CN)
L1HK
1640
1648
1644
1633
1643
1649
1650
1651
1629
1649
1630
1645
1640
1650
1630
ꢀ
/
ꢀ
275
309
/
1281
1259
1257
1260
1265
1261
1260
1259
1250
1261
1260
1266
1270
1269
1258
1607
1599
1604
1604
1611
1606
1604
1603
1603
1606
1600
1615
1603
1615
1607
1
1373
1335
2
L2HK
ꢀ/
ꢀ/
3
1347
1357
1327
1326
296
292
323
325
4
5
6
L4HK
ꢀ/
1357
1326
ꢀ/
292
304
7
8
L5HK
L5HNa
9
ꢀ/
ꢀ/
1330
1330
ꢀ/
ꢀ/
320
300
10

106
T.S. Basu Baul et al. / Journal of Organometallic Chemistry 654 (2002) 100ꢀ108
/
Table 5
119Sn Mossbauer (mm sꢂ1) data for the representative triorganoti-
n(IV) complexes
methine nitrogen in bonding to tin. Thus, the spectro-
scopic data suggest that the structures of these
triorganotin carboxylates may well involve bridging by
phenolic oxygen atoms. This conclusion was confirmed
by the results of X-ray structural analysis for complexes
2 and 4.
¨
a
Complex
Mossbauer data
¨
d
D
G1
G2
2
3
1.23
1.18
1.23
1.23
1.12
2.98
3.03
3.35
3.02
3.08
0.90
0.92
0.92
0.91
0.92
0.91
0.97
0.91
0.91
0.96
3.4. Mossbauer data
¨
4
6
10
In order to obtain further structural evidence, the
Mossbauer spectra of the representative complexes have
¨
been recorded in the solid state (Table 5). The isomer
a
Parameters: d: isomer shifts; D: quadrupole splitting and G1 and
G2: line widths.
shift (d) values, which lie in the range 1.12ꢀ1.23 mm
/
sꢂ1, are typical of quadrivalent organotin derivatives
[24]. This means that the total s-electron density at the
tin nucleus is essentially the same for all the complexes.
This consistency of s-electron density about the tin atom
suggests that there is no significant difference in the
coordination around the tin atom with changes in the
ligand substituents. The spectra of the complexes show a
characteristic doublet absorption indicating a single tin
site and the quadrupole splitting (D) values lie in the
/
increase the likelihood of coordination by the phenolic
oxygen to the tin atom which is also reflected in the
n(Phꢁ
/
(CO)) vibration (see Table 4). Bands due to n(Cꢀ
/
N) have been detected in the complexes at around 1605
cmꢂ1 and showed no change when compared with the
ligand values, indicating non-participation of the azo-
Table 6
Crystallographic data for 2 and 4
range 2.98ꢀ
/
3.35 mm sꢂ1. Values of D in the range 3.0ꢀ
Parameters
2
4
4.1 mm sꢂ1 are typical for structures with a planar SnR3
unit and two apical oxygens [24]. A similar range of
values were also found in the triorganotin derivatives of
amino acids with a trans-trigonal bipyramidal geometry
Empirical formula
Formula weight
Crystal size (mm)
C27H23NO3Sn
528.15
C13H19NO3Sn
355.98
0.42ꢄ0.54ꢄ0.48
0.06ꢄ0.66ꢄ0.33
Yellow, block
Colour and morphol- Yellow, block
ogy
[25]. The full width of half maximum (G9) of these
/
resonance absorptions are ca. 0.94 mm sꢂ1, further
suggesting the presence of a single tin atom site in the
structure.
Crystal system
Space group
Monoclinic
P21/n
Monoclinic
P21/c
˚
a (A)
10.7790(12)
13.3111(13)
16.1450(19)
91.132(9)
2316.0(4)
4
10.7327(14)
13.010(2)
10.5513(14)
90.458(9)
1473.3(4)
4
˚
b (A)
˚
c (A)
b (0)
3.5. X-ray diffraction analysis for Ph3SnL1H (2) and
Me3SnL4H (4)
3
V (A )
˚
Z
Dcalc (g cmꢂ3
Temperature (K)
)
1.515
293(2)
1.605
293(2)
1.734, 712
Pertinent crystallographic parameters are summarized
in Table 6. The atomic numbering scheme and the
Absorption coefficient 1.132, 1064
(mmꢂ1), F(000)
u Range for data col- 2.2ꢀ
/
27.5
2.5ꢀ/30.0
lection (8)
Reflections collected 5591
3876
3744 (Rintꢃ0.0254)
Independent reflec-
tions
Absorption correction Empirical
5316 (Rintꢃ0.0257)
Semi- empirical from
psi-scans
1.000 and 0.449
Max/min transmis-
sion
Refinement method
0.273 and 0.222
Full-matrix least-
square on F2
Full-matrix least-
square on F2
3744/0/190
Data/restraints/para- 5316/0/315
meters
Goodness-of-fit on F2 1.01
1.05
Final R indices
(I ꢀ2s(I))
R indices (all data)
R1ꢃ0.039,
wR2ꢃ0.081
R1ꢃ0.062,
wR2ꢃ0.089
R1ꢃ0.031,
wR2ꢃ0.077
R1ꢃ0.041,
wR2ꢃ0.083
0.0013(3)
Extinction coefficient Not applied
Largest difference
0.49 andꢂ0.35
0.50 and ꢂ0.45
Fig. 2. Molecular structure and crystallographic numbering scheme
for 2.
ꢂ3
˚
peak and hole (e A
)

T.S. Basu Baul et al. / Journal of Organometallic Chemistry 654 (2002) 100ꢀ
/108
107
Table 8
˚
Selected bond lengths (A) and angles (8) for the organotin complex 4
Bond lengths
SnꢁC(2M)
SnꢁC(3M)
SnꢁC(1M)
SnꢁO(2)#1
SnꢁO(1)
O(1)ꢁC(2)
O(2)ꢁC(10)
O(2)ꢁSn#2
O(3)ꢁC(10)
N(1)ꢁC(7)
N(1)ꢁC(9)
C(1)ꢁC(7)
C(7)ꢁC(8)
C(9)ꢁC(10)
2.117(4)
2.120(3)
2.127(4)
2.185(2)
2.353(2)
1.304(4)
1.275(4)
2.185(2)
1.213(3)
1.292(4)
1.447(4)
1.450(4)
1.508(5)
1.525(4)
C(2M)ꢁSnꢁO(1)
C(3M)ꢁSnꢁO(1)
C(1M)ꢁSnꢁO(1)
O(2)#1ꢁSnꢁO(1)
C(2)ꢁO(1)ꢁSn
83.05(12)
89.74(12)
89.63(14)
174.76(9)
139.83(19)
C(10)ꢁO(2)ꢁSn#2 123.92(18)
C(7)ꢁN(1)ꢁC(9)
C(6)ꢁC(1)ꢁC(2)
C(6)ꢁC(1)ꢁC(7)
C(2)ꢁC(1)ꢁC(7)
O(1)ꢁC(2)ꢁC(3)
O(1)ꢁC(2)ꢁC(1)
N(1)ꢁC(7)ꢁC(1)
N(1)ꢁC(7)ꢁC(8)
129.4(3)
118.4(3)
120.3(3)
121.3(3)
121.8(3)
120.6(3)
118.1(3)
119.6(3)
Bond angles
C(2M)ꢁSnꢁC(3M)
C(2M)ꢁSnꢁC(1M)
C(3M)ꢁSnꢁC(1M)
C(2M)ꢁSnꢁO(2)#1
C(3M)ꢁSnꢁO(2)#1
C(1M)ꢁSnꢁO(2)#1
120.91(17) C(1)ꢁC(7)ꢁC(8)
118.65(17) N(1)ꢁC(9)ꢁC(10)
119.85(16) O(3)ꢁC(10)ꢁO(2)
96.16(13) O(3)ꢁC(10)ꢁC(9)
86.22(12) O(2)ꢁC(10)ꢁC(9)
95.28(13)
122.2(3)
111.9(2)
127.7(3)
120.0(3)
112.3(2)
Fig. 3. Molecular structure and crystallographic numbering scheme
Table 7
˚
Selected bond lengths (A) and angles (8) for the organotin complex 2
Symmetry transformations used to generate equivalent atoms: #1
ꢂxꢁ2, yꢂ1/2, ꢂzꢁ1/2; #2 ꢂxꢁ2, yꢁ1/2, ꢂzꢁ1/2.
Bond lengths
SnꢁC(31)
SnꢁC(21)
SnꢁC(11)
SnꢁO(2)
SnꢁO(1A)
O(1)ꢁC(2)
O(1)ꢁSn(2)
O(2)ꢁC(9)
O(3)ꢁC(9)
N(1)ꢁC(7)
N(1)ꢁC(8)
C(1)ꢁC(7)
C(8)ꢁC(9)
2.125(4)
2.128(4)
2.133(4)
2.164(2)
2.357(2)
1.311(4)
2.357(2)
1.282(4)
1.225(4)
1.295(5)
1.453(5)
1.431(6)
1.51(6)
C(11)ꢁSnꢁO(1A)
O(2)ꢁSnꢁO(1A)
C(2)ꢁO(1)ꢁSn(2)
C(9)ꢁO(2)ꢁSn
C(7)ꢁN(1)ꢁC(8)
C(6)ꢁC(1)ꢁC(7)
C(2)ꢁC(1)ꢁC(7)
O(1)ꢁC(2)ꢁC(3)
O(1)ꢁC(2)ꢁC(1)
N(1)ꢁC(7)ꢁC(1)
N(1)ꢁC(8)ꢁC(9)
O(3)ꢁC(9)ꢁO(2)
O(3)ꢁC(9)ꢁC(8)
83.41(12)
167.59(9)
124.0(2)
124.0(2)
124.1(4)
119.0(4)
120.9(3)
122.8(4)
121.0(3)
124.0(4)
113.3(3)
126.4(4)
118.1(3)
adjacent molecule. The ligand is coordinating in the
form of a zwitterion and the carboxylate group is
monodentate. The sum of the carbonꢀ
/
tinꢀcarbon
/
angles in the trigonal plane of complex 2 is 359.21(14)8
while the sum of the corresponding angles for 4 is
359.41(17)8. These carbonꢀ
/
tinꢀcarbon angles are com-
/
parable to those observed in triphenyltin N-salicylidene-
6-aminohexanoate [26] and some other similar com-
plexes [27]. The apical angle subtended at tin in 2 and 4
are 167.59(9) and 174.76(9)8, respectively. The short
Bond angles
tinꢀ
/
oxygen distances are Snꢁ
/
O(carboxylate)ꢃ
A [for 2] and 2.185(2) A [for 4] and SnꢁO(phenolic)ꢃ
2.357(2) [for 2] and 2.353(2) A [for 4]. The former values
are well within the range of SnꢁO bond distances
usually observed for triorganotin carboxylates [4]. It is
interesting to compare the phenolic oxygenꢀtin dis-
/
2.164(2)
C(31)ꢁSnꢁC(21)
C(31)ꢁSnꢁC(11)
C(21)ꢁSnꢁC(11)
C(31)ꢁSnꢁO(2)
C(21)ꢁSnꢁO(2)
C(11)ꢁSnꢁO(2)
C(31)ꢁSnꢁO(1A)
C(21)ꢁSnꢁO(1A)
119.71(14) O(2)ꢁC(9)ꢁC(8)
115.45(15) C(16)ꢁC(11)ꢁSn
123.96(14) C(12)ꢁC(11)ꢁSn
99.32(12) C(26)ꢁC(21)ꢁSn
93.64(12) C(22)ꢁC(21)ꢁSn
86.64(12) C(36)ꢁC(31)ꢁSn
91.66(11) C(32)ꢁC(31)ꢁSn
85.83(11)
115.4(3)
121.3(3)
120.9(3)
123.2(3)
118.8(3)
121.9(3)
120.3(3)
˚
˚
/
/
˚
/
/
˚
˚
tances of 2.357(2) A [for 2] and 2.353(2) A [for 4],
˚
observed here, with that of 3.04 A for triphenyltin
salicylate [28], which corresponds to a much weaker
˚
interaction, and the very similar value of 2.35 A
reported for triphenyltin N-salicylidene-6-aminohex-
Symmetry transformations used to generate equivalent atoms: #1
ꢂxꢁ3/2, yꢂ1/2, ꢂzꢁ1/2; #2 ꢂxꢁ3/2, yꢁ1/2, ꢂzꢁ1/2.
coordination around the tin atom for the complexes 2
and 4 are illustrated in Figs. 2 and 3, respectively.
Selected bond lengths and bond angles are listed in
Table 7 (for 2) and Table 8 (for 4).
anoate [26]. The short Cꢀ
2] and 1.213(3) A [for 4] indicate that the free carbonyl
group on the ligand is not involved in coordination with
/
O distances of 1.225(4) [for
˚
another tin atom. Similar Cꢀ
/O bond lengths have also
Both compounds exhibit the same polymeric struc-
tural motif, namely one in which the tin is five-
coordinate with the three R groups occupying the
equatorial positions and the axial positions of the
trigonal bipyramid being occupied by a carboxylate
oxygen, O(2), and the phenolic oxygen, O(1), of an
been reported for corresponding non-bridging carbonyl
groups in the compounds Ph3SnOCOCH2CH2NH-
˚
CONH2 (1.224(4)
A
[29], and Ph3SnOCOCMeꢀ
/
˚
CHCON(CH2)4 (1.222(5) A) [30]. Proton transfer from
oxygen to nitrogen atoms via hydrogen bonding, and
the formation of zwitterion intermediates in similar

108
T.S. Basu Baul et al. / Journal of Organometallic Chemistry 654 (2002) 100ꢀ108
/
molecules to those discussed here, is quite commonly
encountered [22,31,32]. Thus, the labile phenolic oxygen
is rendered susceptible to coordination with the tin
atom. This makes possible the formation of a series of
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/
O(phenolic) bridges leading to the zigzag polymeric
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/
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Similarities in the spectroscopic data suggest that the
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thermal parameters for non-hydrogen atoms are avail-
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the information may be obtained free of charge from
The Director, CCDC, 12 Union Road, Cambridge CB2
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The financial support of the Department of Science
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F26/98, TSBB) and the support of the MURST, Italy
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