Synthesis and characterization of new di-n-butylhydroxytin(IV) derived compounds from 1,3-diketone malonates

Article abstract of DOI:10.1016/S0277-5387(01)01010-5

The synthesis of four new di-n-butylhydroxytin(IV) derivatives obtained from 1,3-diketone malonates 2a-2d is reported. All compounds were characterized by ¹H, ¹³C, ¹¹⁹Sn NMR, infrared spectroscopy and mass spectrometry (FA

Full text of DOI:10.1016/S0277-5387(01)01010-5

Polyhedron 21 (2002) 417–420
www.elsevier.com/locate/poly
Synthesis and characterization of new di-n-butylhydroxytin(IV)
derived compounds from 1,3-diketone malonates
David Aaro´n Nieto-Alvarez a, Federico Jime´nez-Cruz b, Teresa Mancilla a,*
a Departamento de Qu´ımica, Centro de In6estigacio´n y de Estudios A6anzados del Instituto Polite´cnico Nacional, Apartado Postal 14-740,
CP 07000 Mexico DF, Mexico
b Instituto de Qu´ımica, Uni6ersidad Nacional Auto´noma de Me´xico, Circuito Exterior, Ciudad Uni6ersitaria, CP 04500 Mexico DF, Mexico
Received 8 March 2001; accepted 26 November 2001
Abstract
The synthesis of four new di-n-butylhydroxytin(IV) derivatives obtained from 1,3-diketone malonates 2a–2d is reported. All
1
compounds were characterized by H, 13C, 119Sn NMR, infrared spectroscopy and mass spectrometry (FAB). The 119Sn NMR
spectra at room temperature showed that in CDCl3 solution the tin atom is hexacoordinated. Moreover, the 119Sn NMR spectra
of compound 2a at low temperature exhibits two signals in the range of hexacoordinated compounds, suggesting the existence of
additional species in higher states of aggregation. © 2002 Elsevier Science Ltd. All rights reserved.
Keywords: Tin enolates; Diorganohydroxytin; Diorganotin; Sn(IV) complexes; Malonates; Di-n-butylhydroxytin(IV)
1. Introduction
otin(IV) enolates, which could have biological
properties [18]. This paper describes the synthesis of
new di-n-butylhydroxytin(IV) enolates 2a–2d derived
from 1,3-diketone malonates 1a–1d, where the latter
exist as enolates [19,20], (Fig. 1). All compounds were
Organotin reagents have been extensively studied in
the context of carbonꢀcarbon bond formation [1].
Organotin(IV)enolates in particular have been the sub-
ject of studies with electrophiles such as carbonyl com-
pounds [2–4] and organic halides [5–9]. These reagents
usually exist as mixture of C-stannyl ketone and O-
stannylenolate, the ratio being dependent on structural
factors [10–12]. NMR studies have indicated that
tin(IV)enolates exhibit high-coordinated O-stannyl eno-
lates in the presence of HMPA, which may be responsi-
ble for the selectivity observed in the reactions of
a-haloketones [13]. Tin(IV)enolates have been prepared
by transmetallation of lithium enolates, transesterifica-
tion of enolates and hydrostannation of conjugate car-
bonyls [1]. In spite of the fact that tin(IV)enolates are
relativity more stable than their lithium and silicium
analogous there are few reports concerning their struc-
tures [14]. Our current interest in the synthesis of
organotin(IV) compounds [15–17] prompted us to ex-
tend our investigations in the synthesis of new organ-
1
characterized by H, 13C, 119Sn NMR, infrared spec-
troscopy and mass spectrometry (FAB).
2. Results and discussion
The reaction of 1,3-diketone malonates 1a–1d with
di-n-butyltin(IV) oxide led to di-n-butylhydroxytin(IV)
enolates 2a–2d (Fig. 1). The compounds were
* Corresponding author. Tel.: +(52-55)-57-47-37-23; fax: +(52-
55)-57-47-71-13.
E-mail address: tmancill@mail.cinvestav.mx (T. Mancilla).
Fig. 1. Synthesis of di-n-butylhydroxytin(IV) enolates 2a–2d.
0277-5387/02/$ - see front matter © 2002 Elsevier Science Ltd. All rights reserved.
PII: S0277-5387(01)01010-5

418
D.A. Nieto-Al6arez et al. / Polyhedron 21 (2002) 417–420
Table 1
1H and 119Sn NMR data for compounds 2a–2d
Compound
n-BuSn
CH2CO
2.44 (b)
CH2CH
CHCO2
CH3CO
3.74 (s)
CHvinylic
5.99 (br)
Harom
d119 Sn
2a
Hl: 0.80 (t)
J=7.3
Hg: 1.27 (m)
Hb: 1:34 (m)
Ha: 1.62 (b)
2.66 (q)
J=7.2
3.51 (t)
J=7.4
7.44 (m)
7.86 (d)
J=7.2
−383.82
2b a
2c
Hd: 0.81 (t)
J=7.2
2.45 (b)
2.53 (b)
2.42 (b)
2.33 (q)
J=7.0
3.55 (t)
J=7.4
3.76 (s)
3.77 (s)
3.71 (s)
5.99 (br)
6.09 (br)
5.93 (br)
7.47 (d)
J=8.2
7.86 (d)
J=8.2
−386.82
−378.53
−381.79
Hg,b: 1.27 (m)
Ha: 1.63 (b)
Hd: 0.87 (m)
Hg: 1.25 (m)
Hb: 1.36 (m)
Ha: 1.64 (b)
2.30 (q)
J=7.2
3.52 (t)
J=7.4
8.05 (d)
J=8.5
8.32 (d)
J=8.5
2d
Hd: 0.78 (t)
J=7.1
Hg: 1.25 (m)
Hb: 1.38 (m)
Ha: 1.60 (b)
2.25 (m)
3.49 (m)
7.82 (d)
J=8.4
7.35 (d)
J=8.4
l (1H) relative to Si(CH3)4; l(119Sn) relative to Sn(CH3)4; in CDCl3.
a The singlet at 1.36 ppm is assigned to the protons of the t-Bu group. b, broad; d, doublet; dd, doublet of doublets; m, unresolved pattern;
q, quartet; s, singlet; t, triplet and IJI Hz.
obtained as yellow oils. The 1H and 119Sn NMR data of
2a–2d are summarized in Table 1. An analysis of the
1H NMR spectra showed that both the (n-Bu)2Sn pro-
tons and those due to the ligands are in a 1:1 ratio. This
requires that a OH group be bonded to the tin atom,
although it is not observed, probably due to the forma-
tion of hydrogen bond or to the overlap with other
signals. The CH2CO and CꢁCH vinyl protons appear
as broad signals (0.04 and 0.2 ppm) at higher field with
respect to the free ligands, (1a–1d), which appear as
triplet and singlet signals, respectively. This constitutes
evidence for the formation of a SnꢀO bond between the
enolate moiety and CꢁO“Sn coordination bond, re-
spectively. Their 119Sn chemical shifts in chloroform are
within the range of di-n-butyltin(IV) hexacoordinated
compounds [21–25], suggesting the existance of addi-
tional aggregates in chloroformic solution (Fig. 2).
In order to obtain more information about the struc-
ture of these compounds, a variable-temperature NMR
119Sn study of 2a was undertaken. Thus the 119Sn
spectra in chloroform at 293 and 283 K showed only
one peak at l −383.75 and −383.97, respectively.
However, upon lowering the temperature to 273 and
263 K the signal became broad at l −384.67 and
−384.06, respectively and the spectrum at 253 K exhib-
ited two equally intense resonances at l −383.94 and
−385.16. The same result was observed at 240, 233 and
223 K. The temperature-dependent changes observed in
the spectra are fully reversible, and the data could be
indicative of a fast dynamic equilibrium, on the NMR
time scale, between the aggregates shown in Fig. 2 and
an additional species in a higher state of aggregation,
where the tin atom is also hexacoordinated.
Table 2 shows the 13C NMR data spectra for com-
pounds 2a–2b. The signals assigned to the C5 (enolate)
Fig. 2. State of aggregation of compound 2a at low temperature.

D.A. Nieto-Al6arez et al. / Polyhedron 21 (2002) 417–420
419
cm−1 and broad bands due to the SnꢀO group between
444–432 and 318–302 cm−1
Table 2
13C NMR data for compounds 2a–2d
.
The FAB mass spectra for 2a, 2c and 2d exhibit a
molecular ion corresponding to a dimeric structure and
for all compounds other fragment ions are associated
with an spiroostannolane ion, (Fig. 3). They also ex-
hibit the fragment ion [RC6H4CO]+ at m/z=105
(13%), 161 (26%), 150 (7%) and 139 (15%), respectively.
3. Conclusions
a
Compound
2a
2b
2c
2d
The new diorganotin(IV) compounds 2a–2d were
obtained as enolate derivatives, according to their spec-
troscopic data they are aggregates in solution. The
119Sn variable-temperature NMR study for compound
2a indicated the existence of a dynamic equilibrium
between aggregates, where the tin atoms are hexacoor-
dinated. Their FAB mass spectra exhibit the molecular
ion corresponding to a dimer structure, which supports
the existence of a additional specie aggregated.
C1
C2
C3
C4
C5
C6
C7
C8
C9
C10
C11
C12
Ca
Cb
Cg
Cd
139.32
127.52
128.52
131.62
183.36
96.67
193.56
38.77
25.29
50.87
169.77
52.71
26.87
29.63
26.25
13.57
136.28
127.64
125.79
130.31
183.75
96.60
193.19
39.05
25.73
51.13
169.70
52.96
27.04
29.66
26.28
13.63
130.95
128.32
124.01
149.66
184.00
97.98
193.00
38.10
24.64
50.65
169.69
53.08
26.68
29.61
26.19
13.99
137.84
128.68
128.08
128.77
181.71
97.50
194.56
38.55
25.30
50.81
169.63
52.70
27.15
29.75
27.12
13.74
l: (ppm); in CDCl3.
a The quaternary carbons and methy I group of the t-Bu group
appear at l 35.38 and 31.56, respectively.
Table 3
IR data for compounds 2a–2d
Compound CꢀHarom CꢀHaliph CꢁO
CꢁCꢀCꢀO SnꢀO
2a
2b
2c
2d
3100
3110
3089
3107
2956
2866
1736
1736
1734
1734
1542
1551
1558
1558
432–318
2958
2866
444–314
438–302
442–316
2960
2928
2956
2928
6(cm−1), CHCl3.
and C7 (carbonyl) appear broad and small, indicating
again the formation of the SnꢀOC bond of the enolate
moiety and CꢁO“Sn coordination bond, respectively.
While the C11 (carbonyl ester) exhibits a sharp signal,
which indicates that this carbonyl group does not inter-
act with tin atom. Characteristic IR bands of the
investigated compounds are summarized in Table 3.
Compounds 2a–2d show the band due to the carbonyl
function located between 1736 and 1734 cm−1, a band
due to the enolate group in the range of 1558–1541
Fig. 3. Mass spectral data of compounds 2a–2d.

420
D.A. Nieto-Al6arez et al. / Polyhedron 21 (2002) 417–420
4. Experimental
Acknowledgements
The authors thank the ‘Consejo Nacional de Ciencia
y Tecnologia’ (Conacyt-Me´xico) for financial support
and for research scholarship to D.A.N.A. Thanks to
Guillermo Uribe Rojas for recording the NMR spectra,
Ing. Luis Velasco for recording the FAB-MS and to Dr
Rosa Luisa Santillan B. for reading the manuscript and
for her helpful comments.
4.1. General procedure and measurements
Reagents were purchased from Aldrich Co. 1,3-Dike-
tone malonates 1a–1d were prepared according to the
1
literature [18]. H, 13C and 119Sn NMR spectra were
recorded on Jeol GLX-270 JEOL Eclipse-400 and
Bruker Avance 300-DPX spectrometers. All H and 13C
1
resonances are reported relative to TMS in CDCl3
being used as solvent. High resolution mass spectra
(FAB) were obtained with a Jeol JMS-AX 505 mass
spectrometer, and infrared spectra were recorded on a
Perkin–Elmer 16F PC FT-IR spectrometer.
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4.2. Preparation of compounds 2a–2d
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4.2.1. Synthesis of di-n-butylhydroxy[dimethyl
2-(3-oxo-5-phenylpenten-5-ato)malonate]tin(IV) (2a)
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