Synthesis and characterization of new di-n-butyl[bis{dimethyl-2-(3-oxo-5- phenyl(4-subtituted)penten-5-ato)malonates}]tin(IV): The crystal structure of di-n-butyl[bis{dimethyl-2-[5-(4-nitrophenyl)-3-oxo-penten-5-ato]malonate}] tin(IV)

Article abstract of DOI:10.1016/j.poly.2005.02.024

The synthesis of four new di-n-butyl[bis{dimethyl-2-(3-oxo-5-phenyl(4- subtituted)penten-5-ato)malonates}]tin(IV) 2a-2d is reported. These complexes have been characterized by ¹H, ¹³C, ¹¹⁹Sn NMR, HMQC, HMBC, infrared spectroscopy and mass spectrometry (FAB). Their structures in CDCl₃ solution show a distorted octahedral geometry with a trans disposition of the n-butyl substituents. The ¹¹⁹Sn NMR study at low variable-temperature indicates the presence of trans anti- and syn-isomers, and solid-state ¹³C and ¹¹⁹Sn NMR spectra of compound 2d give also evidence of the mixture of trans isomers. The X-ray diffraction study of compound 2d at 168 K shows only the trans syn-isomer, where the metal is six-coordinated in a skewed trapezoidal bipyramidal (STB) geometry.

Full text of DOI:10.1016/j.poly.2005.02.024

Polyhedron 24 (2005) 1054–1062
www.elsevier.com/locate/poly
Synthesis and characterization of new di-n-butyl
[bis{dimethyl-2-(3-oxo-5-phenyl(4-subtituted)-
penten-5-ato)malonates}]tin(IV): The crystal structure of
di-n-butyl[bis{dimethyl-2-[5-(4-nitrophenyl)-3-oxo-penten-
5-ato]malonate}]tin(IV)
a
David Aaron Nieto-Alvarez , Federico Jimenez-Cruz , Teresa Mancilla
b
a,
*
´
´
a
Departamento de Qu´ımica, Centro de Investigacio´n y de Estudios Avanzados del Instituto Polite´cnico Nacional, Apartado Postal 14-740,
´
CP 07000 Mexico DF, Mexico
b
´ ´ ´ ´ ´
Instituto Mexicano del Petroleo, Eje Central Lazaro Cardenas 152, Col. San Bartolo Atepehuacan, Mexico DF 07730, Mexico
Received 27 August 2004; accepted 25 February 2005
Available online 4 May 2005
Abstract
The synthesis of four new di-n-butyl[bis{dimethyl-2-(3-oxo-5-phenyl(4-subtituted)penten-5-ato)malonates}]tin(IV) 2a–2d is
reported. These complexes have been characterized by 1H, 13C, 119Sn NMR, HMQC, HMBC, infrared spectroscopy and mass spec-
trometry (FAB). Their structures in CDCl3 solution show a distorted octahedral geometry with a trans disposition of the n-butyl
substituents. The 119Sn NMR study at low variable-temperature indicates the presence of trans anti- and syn-isomers, and solid-state
13C and 119Sn NMR spectra of compound 2d give also evidence of the mixture of trans isomers. The X-ray diffraction study of com-
pound 2d at 168 K shows only the trans syn-isomer, where the metal is six-coordinated in a skewed trapezoidal bipyramidal (STB)
geometry.
ꢀ 2005 Elsevier Ltd. All rights reserved.
Keywords: Diorganotin; Tin enolates; Sn(IV) complexes; Malonates; Spectroscopy; X-ray diorganotin
1. Introduction
the halides moiety of a-haloketones [12]. Tin(IV)eno-
lates have been prepared by transmetallation of lithium
enolates, transesterefication of enolates and hydrostan-
nation of conjugate carbonyl compounds [13]. In spite
of the fact that tin(IV)enolates are relativity more stable
than their lithium and silicon analogues, there are few
reports concerning their structures [14]. On the other
hand, it is known that b-diketones exist as a mixture
of diketonic and keto-enolic tautomers and have been
subject to investigation on their coordination behaviour
with several metals [15–17]. In particular organotin(IV)
derivatives of b-diketones have been synthesized [17–
22] for structural studies [16,18–26] as well as for their
antitumor activity [17,20,22]. Recently, we reported the
Organotin(IV) enolates have been the subject of stud-
ies with electrophiles such as carbonyl compounds [1–3]
and organic halides [4–8]. They usually exist as a mix-
ture of C-stannyl ketone and O-stannylenolate, the ratio
depending on structural factors [9–11]. NMR studies
have indicated that tin(IV)enolates exhibit high-coordi-
nated O-stannyl enolates in the presence of HMPA,
which may promote completely selectivity coupling at
*
Corresponding author. Tel.: +52 55 5061 3723; fax: +52 55 5747
7113.
E-mail address: tmancill@cinvestav.mx (T. Mancilla).
0277-5387/$ - see front matter ꢀ 2005 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2005.02.024

´
D. Aaron Nieto-Alvarez et al. / Polyhedron 24 (2005) 1054–1062
1055
R
R
R
n-Bu
OH
O
O
O
C6H6
reflux
Sn
+
n-Bu2SnO
2
O
O
n-Bu
CO2CH3
CO2CH3
CO2CH3
CO2CH3
CO2CH3
CO2CH3
2a: R = H
1a: R = H
2b: R = t-Bu
2c: R = CF3
2d: R = NO2
1b: R = t-Bu
1c: R = CF3
1d: R = NO2
Fig. 1. Synthesis of di-n-butyltin(IV) enolates 2a–2d.
synthesis of new di-n-butylhydroxytin(IV)enolates,
which exhibit higher states of aggregation in solution
at low temperature and their FAB mass spectra showed
a dimer structure [27]. Our current interest in the synthe-
sis of organotin(IV) compounds [28–31] prompted us to
extend our investigations to the synthesis of new
organotin(IV) enolates, which could have biological
properties [32]. This paper describes the synthesis of four
new di-n-butyl[bis{dimethyl-2-(3-oxo-5-phenyl(4-subti-
tuted)penten-5-ato)malonates}]tin(IV) 2a–2d by the
reaction of di-n-butyl(IV) oxide and 1,3-diketone malo-
nates 1a–1d in a 1:2 molar ratio, in which 1a–1d exist as
enolates [33,34] (Fig. 1). All compounds were character-
of these signals can suggest a fluxionality between the
possible isomers [16,19]. 1H NMR data are summarized
in Table 1. The 13C NMR data for compounds 2a–2d
are summarized in Table 2. For all compounds the
assignment of the n-butyl moieties are based on
1
1H–13C HMQC and H–13C HMBC experiments. Thus
a and b carbons correlate with the broad signal around
1.5 ppm of Ha and Hb. The c-carbon correlates with the
signal around 1.27 ppm and d-carbon correlates with the
triplet signal of the methyl group.
The unambiguous assignment of Hb and Hc are
1
based on H–13C HMBC, where the signal of the c-car-
bon correlates with the signal around 1.27 ppm. All
ized by H, 13C, 119Sn NMR, HMQC, HMBC, infrared
these compounds exhibit 1J(119Sn–13C), 2J(119Sn–13C)
1
3
spectroscopy and mass spectrometry (FAB). The com-
pound 2d was also characterized by solid state 13C and
119Sn NMR and its structure was further established
by a single crystal X-ray diffraction study at 168 K.
and J(119Sn–13C) coupling constants within the range
of trans six-coordinated tin compounds [16,17,19–
1
21,26,38]. In particular, J(119Sn–13C) values for com-
pounds 2a–2d are 872, 879, 866 and 860 Hz, respectively
and on the basis of the empirical equation of Holecek
and Lycka [39], it was possible to determine h(C–Sn–
C) of these compounds in CDCl3 solution: the calcu-
lated values are 160.2ꢁ for 2a, 160.9ꢁ for 2b, 159.7ꢁ for
2c and 159.1ꢁ for 2d, which indicate that the tin atom
is in a skewed trapezoidal bipyramidal environment,
where the trapezoidal plane is defined by four oxygen
atoms derived from two asymmetrically coordinating
enolate ligands and the tin-bound organo substituents
are orientated over the weakly bound oxygen atoms
[17,21]. The value calculated for 2d agrees well with
the angle of 157.1(3)ꢁ found in the crystal structure.
The 119Sn NMR spectra of 2a–2c at 19 ꢁC and for 2d
at 25 ꢁC in chloroform show only one peak, which can
indicate a unique species or a fast exchanging equilib-
rium on the NMR time scale (Table 3). Their chemical
shifts are within the range of di-n-butyltin(IV) hexacoor-
dinated compounds [19,23,35–38]. In order to obtain
more information about the structure of these com-
pounds, a variable-temperature NMR study of 2a–2d
2. Results and discussion
The reaction of 1,3-diketone malonates 1a–1d with
di-n-butyltin(IV) oxide in a 2:1 ratio, led to di-n-butyl-
tin(IV)enolates 2a–2d (Fig. 1). The compounds 2a–2c
were obtained as oils, while 2d was a solid. The 1H
NMR spectra in CDCl3 of all the compounds 2a–2d
show only one set of signals for each magnetically equiv-
alent H nucleus, thus both (n-Bu)2Sn protons and those
of the ligands are in a 1:2 ratio, respectively. This can
indicate the formation of a unique species or a fast-
exchanging equilibrium on the NMR timescale. The
H6 and H8 protons appeared as broad signals (0.1
and 0.19 ppm) at higher field with respect to the free li-
gands (1a–1d), which suggests a shielding of these pro-
tons upon coordination [16], giving evidence for the
formation of a Sn–O bonded enolate moiety and a
C@O ! Sn coordination bond, while the broadening

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D. Aaron Nieto-Alvarez et al. / Polyhedron 24 (2005) 1054–1062
1056
Table 1
1H NMR data for compounds 2a–2d
δCH3
γCH2
βCH2
R
R
4
3
2
2a: R = H
αCH2
Sn
1
5
O
O
O
O
2b: R = t-Bu
2c: R = CF3
6
7
n-Bu
8
9
10
12
CO2CH3
2d: R = NO2
CO2CH3
11
CO2CH3
CO2CH3
Compound
n-BuSn
H8
H9
H10
H12
H6
Harom
2a
Hd: 0.78 (t)
J = 7.2
2.42 (b)
2.42 (b)
2.47 (b)
2.26 (q)
J = 7.4
3.50 (t)
J = 7.4
3.72 (s)
3.71 (s)
3.73 (s)
3.73 (s)
5.97 (s)
7.41 (m)
7.87 (d)
J = 7.5
Hc: 1.27 (se)
J = 7.2
Ha,b: 1.48 (m)
2b
2c
2d
Hd: 0.78 (t)
J = 7.2
2.26 (q)
J = 7.4
3.52 (t)
J = 7.4
5.97 (s)
5.99 (s)
6.00 (s)
7.42 (d)
7.82 (d)
J = 8.2
Hc: 1.25 (se)
J = 7.2
Ha,b: 1.44 (m)
Hd: 0.79 (t)
J = 7.3
2.27 (q)
J = 7.3
3.50 (t)
J = 7.3
7.69 (d)
7.98 (d)
J = 8.4
Hc: 1.28 (se)
J = 7.3
Ha,b: 1.50 (m)
Hd: 0.78 (t)
J = 7.3
2.49 (bt)
J = 7.3
2.27 (q)
J = 7.3
3.50 (t)
J = 7.3
8.02 (d)
8.26 (d)
J = 8.8
Hc: 1.29 (se)
J = 7.3
Ha,b: 1.50 (b)
d (1H) relative to Si(CH3)4; d (119Sn) relative to Sn(CH3)4; solvent CDCl3.
The protons of the t-Bu group exhibit a singlet at 1.34 ppm.
b: broad; bt: broad triplet; d: doublet; m: unresolved pattern; q: quartet; s: singlet; t: triplet; se: sextet and |J| Hz.
was undertaken from 45 to ꢀ25 ꢁC for 2a–2c and in the
case of 2d until ꢀ45 ꢁC. Thus the spectra at 45 ꢁC exhi-
bit one signal within the range typical of hexacoordi-
nated tin(IV) compounds, the same result was
observed upon lowering the temperature to ꢀ5 ꢁC for
2a and 2b, but not for 2c and 2d, which showed two
absorptions with slightly different chemical shifts but
equal intensity, indicating the presence of both trans
syn- and anti-isomers, in which the alkyl groups must
be trans, and the isomerism is attributed to a different
arrangement of the two ligands as shown in Fig. 2
[19,21]. The same result is found for compound 2d at
5 ꢁC in which the signals are in ca. 1:4 ratio. All com-
pounds show these two signals at ꢀ25 ꢁC, with equal
intensity for 2a and 2b, while for 2c and 2d in ca. 1:1.5
ratio. The spectrum of 2d at ꢀ35 ꢁC showed three sig-
nals in a ca. 1:2:4 ratio, the first one at d ꢀ183.54 asso-
ciated to a five-coordinate species and the other two to
the six-coordinate species, this result suggests the exis-
tence of an equilibrium between trans isomers through
a five-coordinate species. Its spectrum at ꢀ45 ꢁC exhib-
ited only the signals that belong to the trans isomers in
ca. 1:2 ratio.
These results show the existence of the mixture of
trans isomers in solution at low temperature, where
chemical shifts of the major isomers for 2c and 2d are
at lower frequency. The solid state 119Sn NMR spec-
trum of 2d (Fig. 3) at room temperature exhibits two
signals at ꢀ386.07 and ꢀ402.10 in a ca. 1:1.5 ratio, as
was observed at ꢀ25 ꢁC in solution. Its solid state 13C
NMR spectrum at room temperature exhibits a set of
signals for each magnetically equivalent C nucleus, ex-
cept for C5 and C7, which exhibit two signals each, at
d 200.76, 199.00 and 177.30, 174.40, respectively. The
chemical shifts of the major isomer are at a lower fre-
quency than those on the minor isomer, in approxi-
mately 0.8:1 ratio (Fig. 4). This result can be
attributed again to a different arrangement of the two li-
gands, giving evidence of the existence of the two trans-
isomers.

´
D. Aaron Nieto-Alvarez et al. / Polyhedron 24 (2005) 1054–1062
1057
Table 2
13C NMR data for compounds 2a–2d
Table 3
119Sn NMR variable-temperature data for compounds 2a–2d
δCH3
Compound
2a
2b
2c
2d
γCH2
R
R
4
3
45 ꢁC
35 ꢁC
19 ꢁC
15 ꢁC
5 ꢁC
ꢀ382.93
ꢀ385.37
ꢀ379.12
ꢀ377.15
βCH2
αCH2
Sn
2
ꢀ377.44
2a: R = H
1
ꢀ383.74
ꢀ385.97
ꢀ379.66
ꢀ377.59a
5
O
O
O
O
ꢀ378.09
2b: R = t-Bu
2c: R = CF3
6
ꢀ377.25[1]
ꢀ379.61[4]
ꢀ376.46[1]
ꢀ379.61[1]
ꢀ376.56[1]
ꢀ380.01[1]
ꢀ376.60[1]
ꢀ380.16[1.5]
ꢀ183.54[1]
ꢀ376.60[2]
ꢀ380.16[4]
ꢀ376.60[1]
ꢀ380.21[2]
7
n-Bu
8
9
ꢀ5 ꢁC
ꢀ384.39
ꢀ386.45
ꢀ379.90[1]
ꢀ381.07[1]
10
12
CO2CH3
2d: R = NO2
CO2CH3
11
CO2CH3
CO2CH3
ꢀ15 ꢁC
ꢀ25 ꢁC
ꢀ35 ꢁC
Compound
ꢀ383.81[1]
ꢀ385.08[1]
ꢀ386.54[1]
ꢀ386.84[1]
ꢀ379.07[1]
ꢀ381.74[1.5]
2a
2b
2c
2d
C1
C2
C3
C4
C5
C6
C7
C8
C9
139.30
128.41
127.43
131.55
183.32
96.71
136.17
127.31
125.41
155.11
183.41
96.35
144.84
127.62
125.37
149.40
181.04
97.08
144.86
128.25
123.59
149.40
179.61
97.71
ꢀ45 ꢁC
d: (ppm); solvent CDCl3.
a
Spectrum obtained at 25 ꢁC [ratio].
193.74
38.62
25.17
193.28
38.31
25.17
195.19
38.73
24.90
195.89
38.85
24.81
The FAB mass spectra for 2a–2d exhibit the molecu-
lar ion, which by the loss of one n-Bu group give the
base peaks. Therefore, the fragment ion corresponding
to the loss of one ligand from the molecular ion is ob-
served. The spectra show others fragment ions and a
possible fragmentation pattern is given in Fig. 5.
Compound 2d was recrystallized from methanol to
provide suitable colourless crystals for X-ray diffraction.
Intensity data were collected at 168 K and the crystal
structure corresponds to one of the two isomers seen
in solution and solid state. An ORTEP view of the com-
pound with the numbering scheme is given in Fig. 6.
Bond distances are listed in Table 5. The tin atom is six-
coordinate, showing the metal in skewed trapezoidal
bipyramidal arrangement (STB), where four O atoms
from two ligands, and two C atoms from the n-butyl
groups form the coordination polyhedron. This is a dis-
torted octahedron characterized by two different sets of
C10 50.75
C11 169.69
C12 52.49
50.78
169.69
52.64
50.71
169.51
52.58
50.70
169.47
52.61
Ca 27.83 [872/834] 27.71 [879/842] 28.08 [866/828] 28.22
[860/824]
Cb 27.22 [41]
27.19 [40]
26.39 [132]
13.74
27.12 [41]
26.27 [129]
13.74
27.04 [46]
26.16 [126]
13.68
Cc
Cd
26.36 [133]
13.80
Chemical shifts in ppm with respect to TMS, nJ(13C–119/117Sn) cou-
pling constant between square brackets.
The IR data are summarized in Table 4. The spectra
exhibit two m(C@O) carbonyl oxygen bands, one of them
assigned to the CO2CH3 groups in the range between
1740 and 1734 cmꢀ1 and the other one to the enolate
group between 1615 and 1540 cmꢀ1. Also a broad band
due to Sn–O is observed between 434 and 302 cmꢀ1
.
CO2CH3 CO2CH3
R
R
R
n-Bu
n-Bu
O
O
O
O
Sn
Sn
O
O
O
O
n-Bu
n-Bu
R
CO2CH3 CO2CH3
CO2CH3 CO2CH3
CO2CH3 CO2CH3
Trans-syn
Trans-anti
Fig. 2. trans-isomers for compound 2a–2d.

´
D. Aaron Nieto-Alvarez et al. / Polyhedron 24 (2005) 1054–1062
1058
Fig. 3. Solid state 119Sn NMR spectrum for compound 2d.
Fig. 4. Solid state 13C NMR spectrum for compound 2d.
Sn–O bond. In this context, one ligand has a short bond
˚
length Sn1–O1 = 2.112(4) A (primary bond) and a longer
˚
one, Sn1–O2 = 2.292(5) A (secondary bond). For the
other ligand, the corresponding values are Sn1–
Table 4
IR data for compounds 2a–2d
Compound C–Harom C–Haliph C@O C@C–C–O Sn–O
˚
˚
O3 = 2.115(3) A and Sn1–O4 = 2.349(4) A. The n-Bu
groups are trans to each other although a strong distor-
tion from 180ꢁ is found and the angle is 157.1(3)ꢁ. This
asymmetry in bond length is a result of the asymmetric
nature of the ligand, as well as the presence of the
following intermolecular contacts: NO(6)ꢁ ꢁ ꢁH(191)arom
2.5827(0.0065), C@O(13)ꢁ ꢁ ꢁH(31)arom 2.2576(0.0088),
C@O(9)ꢁ ꢁ ꢁH(281)methynic, 2.5862(0.0101), C@O(15)ꢁ ꢁ ꢁ
H(121)methynic 2.5252(0.0158) and C@O(13)ꢁ ꢁ ꢁH(81)vinylic
2aa
3062
2954
2868
1734
1594
1559
1540
1615
1543
1598
1560
1610
1570
440–304
2ba
2ca
2db
3032
3036
3080
2956
2868
2956
2870
2954
2928
2870
1740
1736
1738
434–302
436–318
450–312
m (cmꢀ1), a Net liquid, bFilm.
˚
2.3372(0.0077) A. Besides the intermolecular contacts,

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D. Aaron Nieto-Alvarez et al. / Polyhedron 24 (2005) 1054–1062
1059
R
R
R
R
+
R
+
.
.
+
.
n-Bu
Sn
n-Bu
Sn
O
O
O
O
O
O
O
O
O
O
-L
-n-Bu
(n-Bu)
Sn
2
n-Bu
CH(CO2CH3)2
m/e (100%)
CH(CO2CH3)2
CH(CO2CH3)2
CH(CO2CH3)2
CH(CO2CH3)2
m/e (%)
+
.
M
(%)
2a: 539
2b: 595
2c: 607
2d: 584
2a: 844 (1)
2b: 956 (2)
2c: 980 (1)
2d: 934 (1)
2a: 787 (25)
2b: 899 (21)
2c: 923 (15)
2d: 877 (16)
-2 n-Bu
R
R
R
+
+
.
+
.
.
m/e (%)
-C5H8O4
2a: 293 (6)
2b: 349 (5)
2c: 361 (6)
2d: 338 (4)
O
O
O
O
O
Sn
O
-2CH3OH
Sn
Sn
-C6H8O4
R
+
.
CH(CO2CH3)2
m/e (%)
O
O
m/e (%)
m/e (%)
2a: 361 (12)
2b: 417 (12)
2c: 429 (11)
2d: 406 (10)
2a: 425 (15)
2b: 481 (14)
2c: 493 (15)
2d: 470 (15)
2a: 281 (7)
2b: 337 (3)
2c: 349 (7)
2d: 326 (5)
O
Sn
OH
Fig. 5. FAB mass spectra for compounds 2a–2d.
Fig. 6. Molecular structure of C40H50N2O16Sn and crystallographic numbering scheme.

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D. Aaron Nieto-Alvarez et al. / Polyhedron 24 (2005) 1054–1062
1060
Table 5
Bond distances selected (A) for C40H50N2O16Sn (2d)
geometry according to their spectroscopic data in solu-
tion. Their 119Sn variable-temperature NMR studies pro-
vide information of the existence of anti and syn trans
isomers, the syn isomer being in the major proportion at
low temperature. The same result was observed in the so-
lid state 13C and 119Sn NMR for compound 2d, while its
X-ray diffraction study at 168 K shows only the syn spe-
cies, which exhibits interesting intermolecular contacts,
NO(6)ꢁ ꢁ ꢁH(191)arom., C@O(13)ꢁ ꢁ ꢁH(31)arom., C@O(15)ꢁ ꢁ ꢁ
H(121)methynic, C@O(9)ꢁ ꢁ ꢁH(281)methynic and C@O(13)ꢁ ꢁ ꢁ
˚
Sn(1)–O(1)
Sn(1)–O(2)
Sn(1)–O(3)
Sn(1)–O(4)
Sn(1)–C(33)
Sn(1)–C(37)
O(1)–C(1)
2.112(4)
2.292(5)
2.115(4)
2.349(4)
2.133(9)
2.134(8)
1.307(7)
C(1)–C(8)
C(8)–C(9)
1.387(9)
1.396(10)
1.261(9)
1.289(7)
1.380(9)
1.416(9)
1.257(8)
C(9)–O(2)
O(3)–C(17)
C(17)–C(24)
C(24)–C(25)
O(4)–C(25)
H(81)vinylic
.
there are the following intramolecular contacts: NO(6)ꢁ ꢁ ꢁ
H(41)arom 2.4553(72), NO(5)ꢁ ꢁ ꢁH(61)arom 2.3962(72),
C–O(7)ꢁ ꢁ ꢁH(121)methynic 2.4265(84), NO(11)ꢁ ꢁ ꢁH(221)arom
2.4682(65), NO(12)ꢁ ꢁ ꢁH(201)arom. 2.4576(74), C@O(15)ꢁ ꢁ ꢁ
H(281)methynic 2.5368(101)andC–O(14)ꢁ ꢁ ꢁ H(271)methylenic
The solid state NMR data, as well as low-tempera-
ture NMR studies should mirror more closely the
structure deduced from the X-ray crystal structure
analysis at 168 K where the molecules are effectively
locked into place by intermolecular forces, therefore
it is possible determine that the major product corre-
sponds to the trans-syn isomer and the minor to the
trans-anti isomer.
˚
2.5674(61) A, which are significantly shorter than the sum
˚
of van der Waals radii of oxygen and hydrogen (2.70 A)
[40].
The six-membered ring Sn(1), O(1), C(1), C(8), C(9),
O(2) adopts an intermediate between envelope and
screw-boat conformation, while the ring Sn(1), O(3),
C(17), C(24), C(25), O(4) adopts an intermediate envelop
and twist conformation, from their puckering parameters
calculated according to Cremer and Pople [41,42], which
are: Q = 0.261, h = 60.35ꢁ, / = 10.56ꢁ and Q = 0.241,
h = 62.06ꢁ, / = 10.64ꢁ, respectively. Therefore the out
of-plane displacements calculated for the atoms of each
ring are: Sn(1), ꢀ0.178(3); O(1), 0.091(6); C(1), 0.034(8);
C(8), ꢀ0.073(8); C(9), ꢀ0.014(9); O(2), 0.139(7) and
Sn(1), ꢀ0.166(3); O(3), 0.122(6); C(17), ꢀ0.001(8);
4. Experimental
4.1. General procedure and measurements
The reagents were purchased from Aldrich Co. 1,3-
Diketone malonates 1a–1d were prepared according to
1
the literature [33,34]. H, 13C and 119Sn NMR spectra
were recorded on Jeol GLX-270, Jeol Eclipse-400 and
Bruker Avance 300-DPX spectrometers, CDCl3 was
used as solvent. The solid state 119Sn and 13C CP-
MAS NMR spectra for compound 2d were obtained
on a Bruker ASX300 at 10.7 and 10.73 KHz, respec-
tively. High resolution mass spectra (FAB) were ob-
tained with a Jeol JMS-AX 505 mass spectrometer,
and infrared spectra were recorded on a Perkin–Elmer
16F PC FT-IR spectrometer. The melting point for
compound 2d was measured in an open capillary tube
on a Gallemkamp MFB-595 apparatus and it was
uncorrected.
˚
C(24), ꢀ0.075(8); C(25), 0.030(8); 0(4), 0.090(6) A, which
give evidence that the six-membered rings do not lie in a
plane [43]. In addition, the equatorial plane made by the
four O atoms has the oxygen atoms associated with the
primary bonds, O(1) and O(3), closer to each other than
those associated with the secondary bond, O(2) and
O(4), as shown by the corresponding angles O(3)–Sn(1)–
O(1) = 79.51(16)ꢁ and O(4)–Sn(1)–O(2) = 118.60(17)ꢁ,
as well as O(1)–O(3) and O(2)–O(4) intramolecular dis-
˚
tances of 2.7034(63) and 3.9915(74) A, respectively.
Therefore, bond angle values for C(33)–Sn(1)–O(1),
C(33)–Sn(1)–O(3), C(37)–Sn(1)–O(1), C(37)–Sn(1)–O(3)
are 99.80(3)ꢁ, 97.10(3)ꢁ, 99.90(2)ꢁ and 97.90(2)ꢁ, which
are bigger than those of C(33)–Sn(1)–O(2) 85.20(3)ꢁ,
C(33)–Sn(1)–O(4) 84.50(3)ꢁ, C(37)–Sn(1)–O(2) 86.40(3)ꢁ
and C(37)–Sn(1)–O(4) 80.90(2)ꢁ, indicating that the
n-Bu groups are folded towards the side of the secondary
bonds.
4.2. Preparation of compounds 2a–2d
The procedure outlined below is general for the prep-
aration of compounds 2a–2d.
4.2.1. Synthesis of di-n-butyl[bis{dimethyl-2-(3-oxo-5-
phenylpenten-5-ato) malonate}]tin(IV) (2a)
A solution of 63.6 mg (0.20 mmol) of 1a in 10 ml of
benzene was placed in a flask equipped with a magnetic
stirrer and Dean-Stark trap and 25.7 mg (0.1 mmol) of
di-n-butyltin(IV) oxide were added. The suspension
was refluxed for 8 h. After being cooled to room tem-
perature, the solvent was evaporated under vacuum.
The residue was treated with chloroform, the solution
was filtered and the solvent was evaporated under
3. Conclusion
The new diorganotin(IV) compounds 2a–2d were ob-
tained as enolate derivatives. The tin atom is hexacoordi-
nated in a skewed trapezoidal bipyramidal (STB)

´
D. Aaron Nieto-Alvarez et al. / Polyhedron 24 (2005) 1054–1062
1061
vacuum to yield 41 mg (49%) of compound 2a as a yel-
low oil.
the FAB-MS, Marco Antonio Leyva for X-ray crystal-
´
lography and Dr. Barbara Gordillo for reading the man-
uscript and for her helpful comments.
4.2.2. Synthesis of di-n-butyl[bis{dimethyl-2-(5-
[4-tertbutylphenyl]-3-oxo-penten-5-ato)-
malonate}]tin(IV) (2b)
Appendix A. Supplementary data
57 mg (0.16 mmol) of compound 1b and 20.3 mg
(0.08 mmol) of di-n-butyltin(IV) oxide gave 60 mg
(78%) of compound 2b as a yellow oil.
Crystallographic data for 2d has been deposited at
the Cambridge Crystallographic Data Center, CCDC
No. 223635. Copies of this information may be obtained
free of charge from The Director, CCDC, 12 Union
Road, Cambridge CB2 1EZ, UK (Fax: +44-1223-366-
033; e-mail: deposit@ccdc.cam.ac.uk or http://www.
ccdc.cam.ac.uk). Supplementary data associated with
this article can be found in the online version at
doi:10.1016/j.poly.2005.02.024.
4.2.3. Synthesis of di-n-butyl[bis{dimethyl-2-(5-
[4-trifluoromethylphenyl]-3-oxo-penten-5-ato)-
malonate}]tin(IV) (2c)
81.7 mg (0.22 mmol) of compound 1c and 27.3 mg
(0.11 mmol) of di-n-butyltin(IV) oxide gave 95 mg
(88%) of compound 2c as a yellow oil.
4.2.4. Synthesis of di-n-buty[bis{dimethyl-2-(5-
[4-nitropheny]-3-oxo-penten-5-ato)-
malonate}]tin(IV) (2d)
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