Dimethyltin(IV) 2,6-disubstituted pyridine complexes

Article abstract of DOI:10.1016/S0022-328X(03)00150-5

The synthesis and characterization of hypervalent pentacoordinated dimethyltin complexes obtained from the reaction of 2,6-disubstituted pyridine ligands with dichlorodimethyltin are reported. The complexes were characterized by mass spectrometry, ^1<

Full text of DOI:10.1016/S0022-328X(03)00150-5

Journal of Organometallic Chemistry 672 (2003) 115ꢀ122
/
www.elsevier.com/locate/jorganchem
Dimethyltin(IV) 2,6-disubstituted pyridine complexes
Elizabeth Go´mez a,*, Rosario Flores a, Gloria Huerta a, Cecilio Alvarez-Toledano a,
Rube´n A. Toscano a, V´ıctor Santes b, Noel Nava c, Pankaj Sharma a
a Instituto de Qu´ımica-UNAM, Circuito Exterior, Ciudad Universitaria, Coyoaca´n, C.P. 04510, Mexico City D.F., Mexico
b Instituto Mexicano del Petro´leo, Programa de Tratamiento de Crudo Maya, Eje Central La´zaro Ca´rdenas 152, Col. San Bartolo Atepehuacan, C.P.
07730, Mexico City D.F., Mexico
c Instituto Mexicano del Petro´leo, Programa de Ingenier´ıa Molecular, Eje Central La´zaro Ca´rdenas 152, Col. San Bartolo Atepehuacan, C.P. 07730,
Mexico City D.F., Mexico
Received 5 December 2002; received in revised form 27 February 2003; accepted 3 March 2003
Abstract
The synthesis and characterization of hypervalent pentacoordinated dimethyltin complexes obtained from the reaction of 2,6-
disubstituted pyridine ligands with dichlorodimethyltin are reported. The complexes were characterized by mass spectrometry, 1H-,
13C- and 119Sn-NMR and Mossbauer spectroscopy, additionally the structures for two compounds were established by X-ray
¨
diffraction analysis. The structural parameters indicated pentacoordinated structures, which present SnꢀN interaction and trigonal
/
bipyramidal tin environment.
# 2003 Elsevier Science B.V. All rights reserved.
Keywords: Tin(IV); Pentacoordinated; Pyridine; 119Sn-NMR; X-ray diffraction; Mossbauer spectroscopy
¨
1. Introduction
described. The reaction of 2-pyridylthiolate with dior-
ganotin oxide gives monomeric molecules [15], whereas
the same reaction using 2-methylthio-3-pyridinecarbox-
ylate as ligand leads to dimeric or monomeric complexes
[16]. The 2,6-pyridinedicarboxylic acid reacts with
diorganotin oxide or diorganotin diacetate affording
structures with pentagonal bipyramidal environment
Organotin compounds are of great interest and they
have been subject of diverse studies owing to their
anticancer activity [1ꢀ4] as well as their applications as
/
biocides [5,6]. Among these fascinating compounds
especial interest has been dedicated to the study of
organostannyl carboxylates due to they adopt several
structural variations leading to different structure activ-
ity relationships [7,8]. Tin complexes with phosphonate
ligands are also important because they can provide
information about metabolism in living organisms [9].
Otherwise, from the structural point of view several
hypervalent organotin complexes have been reported
which include derivatives containing nitrogen and
calcogen atoms [10], Schiff bases [11,12] and pyridine
ligands [13,14]. It is known that pyridine ligands are
excellent complexing agents and various examples are
[17ꢀ22] and similar results are obtained by using the
/
pyridine-2-phosphonate-6-carboxylate as ligand [23].
Additionally, it is also reported that the reaction of
2,6-dimethanol pyridine with diorganotin oxide yields
monomeric species [24,25]. Our interest on organosilicon
compounds led us to study the reactivity of different
ligands containing pyridine moieties with organosilicon
precursors. Interestingly, we found that the formation of
monomeric or dimeric species is influenced by the nature
of substituents at the pyridine ligand [26ꢀ28]. In
/
continuing with our studies, we report herein the
synthesis and characterization by multinuclear NMR,
Mossbauer spectroscopy and X-ray examination of
¨
monomeric tin complexes.
* Corresponding author. Fax: ꢁ
E-mail address: elgomez@correo.unam.mx (E. Go´mez).
/
52-5-5561-62217.
0022-328X/03/$ - see front matter # 2003 Elsevier Science B.V. All rights reserved.
doi:10.1016/S0022-328X(03)00150-5

116
E. Go´mez et al. / Journal of Organometallic Chemistry 672 (2003) 115ꢀ122
/
2. Results and discussion
Snꢀ
/
C angles was based on measurement of the 119Sn
Sn (dꢂ1.0,
satellites coupling constants for CH3ꢀ
/
/
J(13Cꢀ119
J(13Cꢀ119
J(13Cꢀ119
/
Sn)ꢂ
Sn)ꢂ
Sn)ꢂ
calculate angles of 126.4, 125.6 and 125.88 for 2aꢀ
respectively [29]. Furthermore, 119Sn-NMR spectra of
2aꢀ2c showed singlets at ꢃ95.0, ꢃ93.5 and ꢃ93.8 ppm,
which agreed with those reported for pentacoordinated
structures with an intramolecular N0Sn coordination.
These data in combination with the spinꢀspin coupling
/627.7
Hz,
for
2a),
(dꢂ/0.17,
Compounds 1aꢀ1c were prepared by reaction of
/
dimethyl 2,6-pyridinedicarboxylate with the correspond-
ing reagent MeLi or Grignard, which were reacted with
dimethyltin dichloride and triethylamine, affording the
/
/623.0
Hz,
for
2b),
(dꢂ/0.28,
/
/624.2 Hz, for 2c), which were used to
/2c,
organostannyl derivatives 2aꢀ
Mass spectrometry determination was done by using
FABꢁ method which showed the molecular ions m/zꢂ
344, 592 and 816 corresponding to 2aꢀ2c, respectively.
In addition, fragment ions C5H3N-2,6-
(CR2O)(CRO)Sn(Me)2ꢁ, C5H3N-2,6-(CR2O)2SnMeꢁ,
C5H3N-2,6-(CO)2Snꢁ were also detected. The fragmen-
tation pattern is similar to that earlier reported [24,25].
/
2c as shown in Scheme 1.
/
/
/
/
/
/
/
/
constants allowed us to establish that all of these
compounds exhibit pentacoordinated geometry in solu-
tion.
Proton NMR spectra of 2aꢀ2c showed singlets at d
/
The X-ray diffraction structures of 2b and 2c were
established at r.t., crystallographic data, and selected
bond lengths and angles are summarised in Tables 2 and
3. The 2c complex crystallised from ethyl acetate in the
0.52, 0.35 and 0.36 corresponding to the protons of
methyl groups attached to the tin atom. Signals for the
pyridine ring are slightly shifted to high frequencies
1c. Additionally, 119Sn and
¯
space group P1, the crystal lattice also contains solvent
compared to the ligands 1aꢀ
/
117Sn satellites due to coupling Hꢀ119
were also observed. It is well known that the magnitude
/
Sn and Hꢀ117
Sn
/
1
1
molecules, whereas the 2b complex crystallised in the
non-centrosymmetric space group P21 despite the fact
that the molecule is achiral; however, this can be
attributed to deviation of the ideal symmetry 2/m.
The coordination around the tin atom for complexes
2b and 2c is illustrated in Figs. 1 and 2; both compounds
display similar structure where the tin atom is five-
coordinated. The geometry can be considered as a
distorted trigonal bipyramidal, with carbon and nitro-
gen atoms occupying the equatorial positions whereas
the oxygen atoms the apical positions. Bond angles for
2
of j J(119Snꢀ1
/
H)j spinꢀ
/
spin coupling constant is func-
tion of the coordination number in dimethyl tin(IV)
compounds. Values for this type of structures are in the
range of 64ꢀ
reported elsewhere [29,30]. We found values of
2J(119Snꢀ1
H)ꢂ74.9, 75.0 and 74.9 Hz for 2aꢀ2c,
/
79 for pentacoordinated complexes as
/
/
/
respectively, which are in agreement with this observa-
tion. 13C-NMR signals for the pyridine ring carbons are
shifted to low frequencies (Ddꢂ
ligands (see Table 1); this fact is attributed to the
presence of the coordinative N0Sn bond. It is worth
mentioning that silicon structures with N0Si bond
exhibit the same behavior [27]. Determination of the Cꢀ
/
ꢀ3) with respect to
/
the moiety C(9)ꢀ
/
SnꢀC(8) shows values of 121.8(2)/
/
/
123.7(2) for 2a/2b which accounts for the proposed
/
geometry. However, it is worth noting that the bond
/
angle Oꢀ
/
SnꢀO 138.2(1)/140.6(1)8 of 2a/2b is strongly
/
Scheme 1.

Table 1
1H-, 13C- and 119Sn-NMR data for 1a, 1b, 2aꢀ
/2c
CH3
H-3
H-4
CH3 ꢀ/Sn
H-arom
119Sn
1a 1.56 (9H, s)
7.30 (2H, d,
7.72 (2H, d,
Jꢂ7.8)
7.59 (2H, d,
Jꢂ7.8)
7.95 (2H, t,
Jꢂ7.7)
7.85 (1H, t,
Jꢂ7.8)
7.85 (1H, t,
Jꢂ7.8)
Jꢂ
7.06 (2H, d,
Jꢂ7.7)
2a 1.50 (12H, s, 7.43 (2H, d,
CH3) Jꢂ7.7)
7.41 (2H, d,
Jꢂ7.7)
7.45 (2H, d,
Jꢂ7.7)
/
7.8)
/
1b
7.23ꢀ
/
7.30 (20H, m)
7.31 (20H, m)
/
/
0.52 (6H, s, 2J(117Snꢀ1
2J(119Snꢀ1
H)ꢂ74.9 Hz)
0.35 (6H, s, 2J(117Snꢀ1
H)ꢂ
2J(119Snꢀ1
H)ꢂ75.0 Hz)
0.36 (6H, s, 2J(117Snꢀ1
H)ꢂ
2J(119Snꢀ1
H)ꢂ74.9 Hz)
/
H)ꢂ
/
71.0,
71.7,
72.0,
ꢃ
95.0
/
/
/
/
/
2b
2c
/
/
7.25ꢀ
/
ꢃ
/
/
/
/
/
93.5
/
/
7.16 and 7.26 (16H,
AA?BB?, Jꢂ 8.3 Hz)
ꢃ
/
/
/
/
/
/
93.8
C-1
C-2
C-3
C-4
CH3
C-5
C-6 C-7 C-8 C-i
C-o C-m C-p C-9 CH3Sn
1a 72.3
1b 81.4
2a 70.9
164.5
162.5
166.2
(JC ꢀ Sn
116.8
121.6
118.5
138.1
137.1
141.2
30.6
145.9 128.0 128.2 127.5
32.9
31.4
1.0 (JC ꢀ Sn
627.7)
ꢂ600,
/
(JC ꢀ Sn
34.6)
ꢂ
/
ꢂ
/
57.7) (JC ꢀ Sn
ꢂ
/
19.6)
18.5)
20.8)
2b 81.5
163.2
(JC ꢀ Sn
123.0
48.5) (JC ꢀ Sn
139.8
139.6
148.4 128.0 127.8 127.2
0.17 (JC ꢀ Sn
596.5, 623.0)
ꢂ/
(JC ꢀ Sn
33.5)
2c a 81.0
ꢂ/
ꢂ/
ꢂ/
163.3
(JC ꢀ Sn
122.7
49.6) (JC ꢀ Sn
145.4 127.5 124.8 149.8
34.5 0.28 (JC ꢀ Sn
596.5, 624.2)
ꢂ/
(JC ꢀ Sn
33.5)
ꢂ/
ꢂ/
ꢂ/
a
The chemical shifts for C-5ꢀ
/
C-8 correspond to C-30ꢀC-33 according to the X-ray structure numbering.
/

118
E. Go´mez et al. / Journal of Organometallic Chemistry 672 (2003) 115ꢀ122
/
Table 2
Crystallographic data for compounds 2b and 2c
Table 3
Selected bond lengths (A) and bond angles (8) for 2b and 2c
˚
2b
2c
2b
2c
Formula
C
33H29NO2Sn
C49H61NO2Sn×
0.5EtAc
858.73
/
Bond lengths
Sn(1)ꢀ
Sn(1)ꢀ
Sn(1)ꢀ
Sn(1)ꢀ
Sn(1)ꢀ
/
O(1)
O(2)
C(9)
C(8)
N(1)
2.056(3)
2.073(3)
2.092(4)
2.103(4)
2.209(3)
1.382(4)
1.390(3)
1.325(5)
1.333(5)
1.537(6)
1.552(5)
2.036(3)
2.028(3)
2.104(5)
2.095(5)
2.204(4)
1.405(5)
1.412(5)
1.339(6)
1.343(5)
1.563(6)
1.530(7)
Formula weight (g molꢃ1
Crystal size (mm3)
)
590.26
/
0.262ꢄ
0.133
/0.214ꢄ
/
0.211ꢄ/0.116ꢄ
/
/
0.056
/
Color
Colorless
Monoclinic
P21
Colorless
Triclinic
¯
P1
/
Crystal system
Space group
Unit cell dimensions
O(1)ꢀ
O(2)ꢀ
N(1)ꢀ
N(1)ꢀ
C(1)ꢀ
C(6)ꢀ
/
C(1)
/C(7)
/
C(2)
C(6)
C(2)
C(7)
˚
a (A)
8.613(1)
13.740 (1)
11.849(1)
90
10.208(1)
15.438(1)
15.466(3)
83.041(2)
74.211(2)
85.538(2)
2325.5(3)
2
/
˚
b (A)
/
˚
c (A)
/
a (8)
b (8)
g (8)
Bond angles
90.732(1)
90
O(1)ꢀ
O(1)ꢀ
O(2)ꢀ
O(1)ꢀ
O(2)ꢀ
C(9)ꢀ
O(1)ꢀ
O(2)ꢀ
C(9)ꢀ
C(8)ꢀ
C(1)ꢀ
C(7)ꢀ
C(2)ꢀ
C(2)ꢀ
C(6)ꢀ
/
Snꢀ
Snꢀ
Snꢀ
Snꢀ
Snꢀ
Snꢀ
Snꢀ
Snꢀ
Snꢀ
Snꢀ
/
O(2)
C(9)
C(9)
C(8)
C(8)
138.5(1)
95.3(2)
92.1(2)
140.6(1)
94.1(2)
93.6(2)
/
/
3
˚
V (A )
1402.1(1)
2
1.398
/
/
Z
/
/
104.0(2)
106.4(2)
121.8(2)
73.2(1)
103.3(2)
104.2(2)
123.7(2)
73.7(1)
Dcalc (g cmꢃ3
)
1.226
26758
8200(0.0876)
/
/
No. of collected reflections 11566
No. of independent reflec- 4935(0.0358)
/
/
C(8)
/
/
N(1)
N(1)
tions (Rint
No. of observed reflections 4935
)
/
/
73.2(1)
73.6(1)
8200
494
/
/
N(1)
N(1)
135.5(2)
102.6(2)
120.1(2)
121.1(2)
123.3(4)
118.0(3)
118.5(3)
134.7(2)
101.6(2)
121.6(3)
123.7(3)
124.3(5)
117.3(4)
118.4(4)
No. of parameters
a
336
/
/
R
0.034
0.051
1.09
0.062
0.082
1.11
/
O(1)ꢀ
O(2)ꢀ
N(1)ꢀ
N(1)ꢀ
N(1)ꢀ
/Sn
b
Rw
GOF
/
/Sn
/
/
C(6)
Sn
/
/
a
Rꢂ
/
ajjFojꢃ
/
jFcjj/ajFoj.
F2c)2/a wF4o]1/2
/
/
Sn
b
Rw(Fo)2ꢂ[a w(F2oꢃ
/
/
.
compounds. It should be noted, that values of QS and IS
for 2aꢀ2c are in agreement with those reported for
distorted from the ideal angle for a bipyramidal trigonal
geometry, which can be the result of the ring constraint.
/
similar pentacoordinated organotin structures [31].
In conclusion, pyridine diol ligands in reaction with
dimethyltin dichloride afford selectively monomeric
five-coordinated tin complexes. In all cases, the geome-
try is strongly distorted towards bipyramidal trigonal as
It is important to mention that the values for Cꢀ
bond angles found in solid state are in agreement with
calculations performed from the NMR data in solution.
/
SnꢀC
/
The SnꢀN bond distance for 2b is 2.209(3) and
/
˚
2.204(4) A for 2c, which are slightly shorter than those
found for related compounds possessing penta and
seven coordinated tin atom [12,17,19,20]. Furthermore,
shown by the X-ray examination and the Mossbauer
¨
spectroscopic study. In addition, it is established that the
solid-state structures of dimethyltin compounds are
retained in solution as deduced from the NMR spectro-
scopic study.
the SnꢀO bond distances are in accordance with
/
previous reports concerning pentacoordinated tin spe-
cies [8].
In order to gain structural information in the solid
state, we carried out a Mossbauer spectroscopic study.
¨
3. Experimental
All spectra were obtained at 10 K and they are depicted
in Fig. 3; parameters involved are summarised in Table
2,6-Pyridinedicarboxylate, MeLi and bromobenzene
were purchased from Aldrich. All reactions were carried
out under nitrogen atmosphere; the solvents were care-
fully dried and distilled from the appropriate drying
4. The Mossbauer spectra of 2aꢀ2c compounds show a
/
¨
doublet with values of IS ranging from 0.894 to 0.977
mm sꢃ1 whereas QS show values from 1.844 to 2.026
mm sꢃ1, which are typical for Sn(IV) pentacoordinated
compounds [25]. The differences observed in IS and QS
1
agents prior to use. H-, 13C- and 119Sn-NMR spectra
were recorded on a JEOL Eclipse ꢁ300, chemical shifts
/
for compounds 2aꢀ2c are negligible, it therefore means
/
(ppm) are relative to the TMS and (CH3)4Sn. Mass
spectra were obtained on JEOL JMS-AX505 HA;
Melting points were measured on a Melt-b Temp II
and are uncorrected. The X-ray crystallography studies
that all of these complexes posses the same geometry
around the tin atom, which correspond to pentacoordi-
nated structures displaced towards trigonal bipyramidal
as supported by the X-ray diffraction for 2b and 2c
were done on a Siemens P4/PC diffractometer l(Moꢀ
/

E. Go´mez et al. / Journal of Organometallic Chemistry 672 (2003) 115ꢀ
/122
119
Fig. 1. Molecular structure for compound 2b.
˚
Ka)ꢂ
/
0.71073 A, graphite monochromator, Tꢂ
/
293 K,
position with isotropic temperature factor 1.2 times the
Uiso of the parent carbon atom. Mossbauer spectra were
v ꢀ2u scan, range 1.5B
/
/
u B258. Corrections were done
/
¨
for Lorentz and polarization effects. The structures were
solved by direct methods (SHELXS-86); all nonhydrogen
atoms were refined anisotropically, by full least-squares,
collected at 10 K, the spectrometer was operated in the
constant acceleration mode in transmission experiments,
with a 15 mCi (555 MBq) single-line gamma-ray source
of Ba119mSnO3. The temperature of the source was 295
K during the measurements. Detection of the 23.8 keV
g-rays was achieved with a Kr proportional counter and
(SHELXL-97) [32]. Absorption correction for compounds
2b and 2c based on psi-scans were applied; hydrogen
atoms bound to carbon atoms inserted at calculated
Fig. 2. Molecular structure for compound 2c.

120
E. Go´mez et al. / Journal of Organometallic Chemistry 672 (2003) 115ꢀ122
/
Fig. 3. Mossbauer spectra of 2a, 2b and 2c.
¨
a 0.05 mm thick Pd foil was placed between the source,
and detector to filter 25.0 and 25.2 keV X-rays from the
source. The source was moved by a loud-speaker drive
with a sinusoidal velocity relative to the stationary
absorber. Its velocity was regulated and followed the
sine wave to within 0.1%. The chemical isomer shift (IS)
data are quoted relative to Ba119mSnO3. The absorption
spectra were computer fitted by using the NORMOS
program.
after extraction with methylene chloride (3ꢄ
dark oil was obtained, which was chromatographed on
silica gel with n-hexaneꢀethyl acetate obtaining 1.52 g
(60%) of colorless crystals of 1a [33]; m.p. 94ꢀ
95 8C; 1H-
NMR (300 MHz, CDCl3) d: 1.56 (9H, s, CH3), 7.30
7.8 Hz, H-4);
13C-NMR (75.412 MHz, CDCl3) d: 30.6 (CH3), 72.3 (C-
1), 116.8 (C-3), 138.1 (C-4), 164.5 (C-2); MS, m/z (%):
195 [Mꢁ,(2)], 180 (42), 162 (100), 138 (17), 118 (24), 104
(14), 78 (10), 59(15), 43 (22), 31 (12).
/
30 ml) a
/
/
(2H, d, Jꢂ
/
7.8 Hz, H-3), 7.72 (1H, t, Jꢂ
/
3.1. 2,6-Bis-(1-hydroxy-1-methyl-ethyl) pyridine (1a)
MeLi (52 ml, 0.55 M) was added to a solution of
dimethyl 2,6-pyridinedicarboxylate (1.1 g, 5.75 mmol) in
THF, the reaction mixture was stirred 24 h at room
temperature (r.t.), then it was treated with water, and
3.2. 2,6-Bis-(1-hydroxy-1,1-diphenyl-methyl) pyridine
(1b)
The compound 1b was prepared according to a
procedure described in the literature [27]:From 4.3 ml
(10.25 mmol) bromobenzene, 1.20 g (40.98 mmol)
magnesium and 1.20 g (10.25 mmol) of dimethyl 2,6-
pyridinedicarboxylate, the resulting yellow oil crystal-
lized from acetone obtaining 2.87 g (63%) of colorless
Table 4
119Sn Mossbauer parameters of 2aꢀ
/2c
¨
a
b
Sample IS (mm sꢃ1
)
QS (mm sꢃ1
)
G1; G2 (mm sꢃ1
)
crystals; m.p. 124ꢀ
d: 7.06 (2H, d, Jꢂ
arom), 7.59 (1H, t, Jꢂ
/
128 8C; 1H-NMR (300 MHz, CDCl3)
7.7 Hz, H-3), 7.23ꢀ7.30 (20H, m,
7.8 Hz, H-4); 13C-NMR (75.412
/
/
2a
2b
2c
0.8949
0.9779
0.9689
/
0.008
0.002
0.011
1.8449
2.0269
1.9899
/
0.014
0.003
0.006
1.1879
1.1129
1.1109
/
0.023
0.005
0.033
/
/
/
/
/
/
/
MHz, CDCl3) d: 81.4 (C-1), 121.6 (C-3), 127.5 (C-p),
128.0 (C-o), 128.2 (C-m), 137.1 (C-4), 145.9 (C-i), 162.5
a
Isomer shift relative to Ba119mSnO3.
b
(C-2); MS, m/z (%): 444 [Mꢁꢁ1, (14.6)], 443 [Mꢁ,
(42.3)], 425 (18.5), 407 (6.0), 348 (20.9), 243 (15.7), 167
/
Full width at half height of the resonant peaks at higher and lower
G2
velocity than the spectrum centroid, respectively; spectra with G1ꢂ
/
were fitted as symmetrical doublets with the NORMOS program.
(5.0), 105( 12.9), 71 (8.3), 50 (53.7), 43 (100), 15 (7.6).

E. Go´mez et al. / Journal of Organometallic Chemistry 672 (2003) 115ꢀ
/122
121
3.3. 2,2,4,4,6,6-Hexamethyl-3,5-dioxa-11-aza-4-stanna-
bicyclo[5.3.1]undeca-1-(10),7(11),8-triene (2a)
nebis(di-4-tert-butylphenylmethanol) (1b), 0.075 g (0.75
mmol) of Et3N, 0.082 g (0.375 mmol) of dimethyltin
dichloride, After 4 h of refluxing, 10 ml of water was
added to remove Et3NHCl, the solvent was evaporated
resulting a pink solid, after crystallized from Ethyl
Acetate 0.292 g (95%) of colorless crystals of 2c were
Dimethyltin dichloride (0.24 g, 1.1 mmol) was added
to a solution of 2,6-pyridinebis(dimethylmethanol) (1a)
(0.216 g, 1.1 mmol) in methylene chloride and of Et3N
(0.22 g, 2.2 mmol). After 6 h of refluxing, 10 ml of water
was added to remove Et3NHCl, the solvent was
obtained; m.p. 231ꢀ
CDCl3) d: 0.36 (6H, s, 2J(119Snꢀ1
2J(117Snꢀ1
H)ꢂ74.9Hz, CH3ꢀSn), 1.27 (9H, s,
(CH3)3), 7.16 and 7.26 (16H, AA?BB?, Jꢂ8.3 Hz, H-
6,H-7), 7.45 (2H,d, Jꢂ7.7 Hz, H-3), 7.85 (1H, t, Jꢂ7.6
Hz, H-4); 13C-NMR (75.58 MHz, CDCl3) d: 0.28
(CH3ꢀ C)ꢂ C)ꢂ624.2
Sn, J(119Snꢀ13 596.5, J(119Snꢀ13
Hz), 31.4 ((CH3)3ꢀC), 34.5 (Cꢀ(CH3)3)), 81.0 (C-1,
J(119/117Snꢀ13
C)ꢂ33.5 Hz), 122.7 (C-3,
J(119/117Snꢀ13
C)ꢂ20.8 Hz), 124.8 (C-7), 127.5 (C-6),
145.4 (C-5), 139.6 (C-4), 149.8 (C-8), 163.3 (C-2,
J(119/117Snꢀ13 49.6 Hz); 119Sn-NMR (112.06 MHz,
C)ꢂ
CDCl3) d: ꢃ93.8; MS (FAB) m/z (%); 816 [(Mꢁ
H)ꢁ,
(100)], 815 [Mꢁ (92)], 814 [(Mꢁꢃ1 (100)], 813[(Mꢁꢃ
(68)], 812[(Mꢁꢃ3 (65)], 800 [(Mꢁꢃ
CH3 (30)], 784 (7),
/
232 8C; 1H-NMR (300 MHz,
H)ꢂ72.0 Hz,
/
/
evaporated resulting a yellow solid, 0.205 g (54%);
1
/
/
/
m.p. 163ꢀ
/
164 8C; H-NMR (300 MHz, CDCl3) d: 0.52
/
(6H, s, 2J(119Snꢀ1
Hz, CH3ꢀSn), 1.50 (12H, s, CH3), 7.43 (2H,d, Jꢂ
H-3), 7.95 (1H, t, H-4), 13C-NMR (75.58 MHz, CDCl3)
d: 1.0 (CH3-Sn, J(117Snꢀ13 599.9, J(119Snꢀ13
C)ꢂ C)ꢂ
627.7 Hz), 32.9 (CH3), 70.9 (C-1, J(119/117Snꢀ13
C)ꢂ
34.6 Hz), 118.5 (C-3, J(119/117Snꢀ13
C)ꢂ19.6 Hz),
141.2 (C-4), 166.2 (C-2, J(119/117Snꢀ13
C)ꢂ57.7Hz);
119Sn-NMR (112.06 MHz, CDCl3) d: ꢃ
95.0; MS
(FAB) m/z (%); 344 [(Mꢁ
H)ꢁ, (100)], 342 [(Mꢁꢃ
(37)], 341 [(Mꢁꢃ2 (77)], 340 [(Mꢁꢃ
3 (31)], 339
[(Mꢁꢃ (45)], 328 [(Mꢁꢃ
CH3 (31)], 312
/
H)ꢂ
/
74.2 Hz, 2J(117Snꢀ1
/
H)ꢂ
/
71.0
/
/
/
/7.7,
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
1
/
/
/
/
/
/2
/
4
/
/
/
(11), 296 (11), 281 (5), 254(3), 102 (54), 55 (22), 43
(20), 29 (5).
767 (5), 682 (79), 632 (25), 576(9), 560 (6), 491 (12), 460
(10), 404 (10), 358 (7), 284 (6), 253 (11), 167 (14), 161
(43), 118 (6), 91 (9), 57 (33), 41(9), 29 (5).
3.4. 4,4-Dimethyl-2,2,6,6-tetraphenyl-3,5-dioxa-11-aza-
4-stanna-bicyclo[5.3.1]undeca-1(10),7(11),8-triene
(2b)
4. Supplementary material
Compound 2b was prepared following the procedure
described for 2a from 0.5 g (1.128 mmol) 2,6-pyridine-
bis(diphenylmethanol) (1b), 0.228 g (2.258 mmol) of
Et3N, 0.247 g (1.128 mmol) of dimethyltin dichloride,
After 4 h of refluxing, 10 ml of water was added to
remove Et3NHCl, the solvent was evaporated resulting
0.424 g (63%) of colorless crystals; m.p. 213 8C; 1H-
NMR (300 MHz, CDCl3) d: 0.35 (6H, s,
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Centre, CCDC nos. 198709 and 188708 for
compounds 2b and 2c, respectively. Copies of this
information may be obtained free of charge from The
Director, CCDC, 12 Union Road, Cambridge CB2 1EZ,
UK (Fax: ꢁ44-1223-336033; e-mail: deposit@ccdc.
/
2J(119Snꢀ1
CH3ꢀSn), 7.25ꢀ
H-3); 7.85(1H, t, H-4); 13C-NMR (75.58 MHz, CDCl3)
d: 0.17(CH3ꢀ C)ꢂ C)ꢂ
Sn, J(117Snꢀ13 596.5, J(119Snꢀ13
623.0 Hz), 81.5 (C-1, J(119/117Snꢀ13
C)ꢂ33.5 Hz), 123.0
(C-3, J(119/117Snꢀ13
C)ꢂ18.5 Hz), 127.2 (C-p), 127.8 (C-
m), 128.0 (C-o), 139.8 (C-4), 148.4 (C-i), 163.2 (C-2,
/
H)ꢂ
/
75.0 Hz, 2J(117Snꢀ1
/
H)ꢂ/71.7 Hz,
cam.ac.uk or www: http://www.ccdc.cam.ac.uk).
/
/
7.31 (20H, m, H-arom), 7.41(2H, d,
/
/
/
/
/
Acknowledgements
/
/
/
/
Financial support from DGAPA (IN216201) is grate-
ful acknowledged. We thank Francisco Javier Pe´rez
Flores and Luis Velasco Ibarra for recording mass
spectra.
J(119/117Snꢀ13
CDCl3) d: ꢃ93.5; MS (FAB), m/z (%); 592 [(Mꢁ
(100)], 590 [(Mꢁꢃ (50)], 589 [(Mꢁꢃ
588[(Mꢁꢃ3 (42)], 587[(Mꢁꢃ
/
C)ꢂ
/
48.5 Hz); 119Sn-NMR (112.06 MHz,
/
/
H)ꢁ,
(79)],
/1
/
2
/
/
4 (42)], 576 [(Mꢁꢃ
/
CH3
(15)], 484 (4), 408 (44), 379 (5), 348 (10), 307 (14),
343(10), 105 (20), 77 (14).
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3.5. 2,2,6,6-Tetrakis-(4-tert-butyl-phenyl)-4,4-dimethyl-
3,5-dioxa-11-aza-4-stanna-bicyclo[5.3.1]undeca-
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