3588
V.N. Dokorou et al. / Journal of Organometallic Chemistry 693 (2008) 3587–3592
orated under vacuum to a small volume (2 ml), chilled and tritu-
rated with acetone to give a yellow solid. The yellow powder
was recrystallized from CH2Cl2 and was dried in vacuo over silica
gel. M.p. 219–221 °C; yield 26%. IR (KBr, cmꢀ1): 3324, 3290
m
(NY), 1614, 1590
m
as(COO), 1373, 1457
m
sym(COO); 569, 522
m(Sn–C); 440, 411
m(Sn–O)2; 281, 225, 218 m
(Sn–O); 1H NMR
Scheme 1.
(CDCl3): d 9.57 (s, 1H, NH), 7.89 (d, H3), 6.89 (d, H4), 7.57 (t, H5),
6.77 (t, H6), 7.65 (dt, H40), 7.37 (t, H50), 7.34 (d H60), 3.31/2.45(s,
CH3), 13C NMR: d 175.7 (COOH), 152.4 (C1), 114.4 (C2), 132.9
(C3), 118.3 (C4), 134.6 (C5), 115.5 (C6), 148.0 (C10), 120.0 (C20),
142.0 (C30), 127.6 (C50) 127.3 (C60) 14.5 (CH3) 10.4/7.80 (ꢀR–Sn)
Anal. Calc.: C, 44.90; H, 4.00; N, 6.15. Found: C, 44.50; H, 4.14; N,
5.90%. Crystals of 2 suitable for X-ray analysis were obtained by
slow evaporation of a CHCl3/CH3CN solution.
by means of vibrational, 1H and 13C NMR. The crystal and molecu-
lar structure of 2 is described. Also, the transesterification reactions
of 2 and 3 are described.
[Me2Sn(MNAB)2] (3). Dimethyl tin(IV) oxide (0.1649 g,
1.0 mmol), HMNAB (0.5989 g, 2.20 mmol) and 30 ml of benzene
were refluxed for 24 h with azeotropic removal of water via a
Dean-Stark trap. The resulting clear solution was rotary evaporated
under vacuum to a small volume (2 ml), chilled and triturated with
acetone to give a bright yellow solid. The yellow powder was
recrystallized from CH2Cl2 and dried in vacuo over silica gel. M.p.
2. Experimental
2.1. General and instrumental
2.1.1. General
The reagents (Aldrich, Merck) were used as supplied while the
solvents were purified according to standard procedures [11c].
Elemental analyses (C, H and N) were carried out by the microan-
alytical service of the University of Ioannina. Melting points were
determined in open capillaries and are uncorrected. Infrared and
far-infrared spectra were recorded on a Perkin–Elmer Spectrum
GX Fourier transform spectrophotometer using KBr pallets
(4000–400 cmꢀ1) and nujol mulls dispersed between polyethyl-
ene disks (400–40 cmꢀ1). The 1H (250.13 MHz), 13C (62.90 MHz)
NMR spectra were recorded on a Bruker AC-250 and on a Bruker
AMX-400 spectrometers. Samples were dissolved in CDCl3 and
spectra were obtained at room temperature with the signal of
the free CDCl3 at 7.24 ppm. GC analysis was performed using a
Shimadzu GC-17A gas chromatograph coupled with a GCMS-
QP5000 mass spectrometer with the following temperature pro-
gram: initial temperature, 80 °C (starting time 5 min); heating
rate, 10 °C/min; final temperature, 150 °C (final time 5 min);
injector temperature, 230 °C. The yields of products were esti-
mated from the peak areas based on the internal standard tech-
nique [11d].
165–166 °C; yield 77%. IR (KBr): 3318
m
(NY), 1666
mas(COO), 1404
m
sym(COO); 569, 545 (Sn–C); 280, 217 m
m
(Sn–O). 1H NMR (CDCl3):
d 9.29 (s, 1H, NH), 8.15 (dd, H3), 6.92 (d, H4), 7.60 (t, H5), 6.85
(t, H6), 7.60 (t, H40), 7.31 (t, H50), 7.35 (d, H60); 3.49/2.17(s, CH3),
13C NMR: d 177.6 (COOH), 151.9 (C1), 112.3 (C2), 133.4 (C3),
118.2 (C4), 135.0 (C5), 113.9 (C6), 147.7 (C10), 119.7 (C20), 141.4
(C30), 121.2 (C40), 127.3 (C50), 126.7 (C60) 13.6 (CH3). Anal. Calc.
for C30H28SnN4O8 (691.2 g molꢀ1): C, 52.10; H, 4.10; N, 8.10.
Found: C, 52.10; H, 4.07; N, 8.26%.
2.3. Catalytic reactions
2-Phenylethanol (1 mM) was slowly added to a solution of eth-
ylacetate (5 ml). As an internal standard acetophenone was used.
Catalytic reaction was started by adding 10 lM of 2 or 3. The ratio
of catalyst: 2-phenylethanol was 1:100. The reaction mixture was
refluxed at 77 °C and the progress of the reaction was monitored
by GC–MS, by removing small samples of the reaction mixture.
To establish the identity of the products unequivocally, the
retention times and spectral data were compared to those of com-
mercially available compounds. Thus, 2-phenylethanol, 2-phenyl-
ethyl acetate and acetophenone were purchased in their highest
commercial purity, stored at 5 °C and purified by passage through
a column of basic alumina prior to use.
2.2. Synthesis
2-(2-Methyl-3-nitroanilino)benzoic acid (HMNAB) (1), was syn-
thesized according to published procedure, the Ullmann–Goldberg
condensation [11a,b]. 2-Methyl-3-nitro-benzenamine (11.26 g,
0.074 mol), potassium 2-bromobenzoate (18.17 g, 0.076 mol), 4-
ethylmorpholine (9.5 ml, 0.076 mol) and 0.8 g of anhydrous copper
acetate in 30 ml of distilled N,N-dimethylformamide under nitro-
gen atmosphere were refluxed at 145 °C for 4 h. In the resulting
solution 20 ml of distilled N,N-dimethylformamide was added,
and 30 ml of 12% hydrochloric acid. The aqueous layer was dec-
anted and methanol was added. The solid was collected and recrys-
tallized three times from acetone. M.p. 222–223 °C. Yield 24.35%
2.4. X-ray crystallography
Slow evaporation of a dilute 1:1 by volume CH3CN/CHCl3 solu-
tion provided a yellow prismatic crystal of 2, which was mounted
on a sealed tube and used for data collection. Cell constants and an
orientation matrix for data collection were obtained by least-
squares refinement of the diffraction data from 25 reflections in
the range 1.34 < h < 26.30° on a Bruker Smart Apex diffractometer.
(2.70 g). IR (KBr): 3323sh m(NY), 1597 mas(COO), 1425 msym(COO);
1H NMR (CDCl3): d 9.30 (s, 1H, NH), 8.07 (dd, H3), 6.83 (t, H4),
7.65 (d, H5), 6.81 (t, H6), 7.57 (d, H40), 7.37 (t, H50), 7.35 (d, H60)
3.49/2.17 (s, CH3), 13C NMR: d 174.1 (COOH), 147,7 (C1), 111.4
(C2), 131.6 (C3), 114.2 (C4), 135.8 (C5), 118.8 (C6), 135.5 (C10),
132.2 (C20), 141.4 (C30), 120.2 (C40), 130.4 (C50). Anal. Calc. for
C14H13N2O4 (272.3 g molꢀ1): C, 61.77; H, 4.44; N, 10.29. Found: C,
61.25; H, 4.10; N, 10.05%.
[Me2(MNAB)SnOSn(MNAB)Me2]2 (2). Dimethyl-tin(IV) oxide
(0.1977 g, 1.2 mmol), HMNAB (0.2723 g, 1.0 mmol) and 30 ml of
benzene were refluxed overnight with azeotropic removal of water
via a Dean-Stark trap. The resulting clear solution was rotary evap-
Data were collected at 293 K using Mo K
and the -scan technique, and corrected for Lorentz and polariza-
tion effects [12]. A semi-empirical absorption correction ( -scans)
a radiation (k = 0.71073 Å)
x
W
was made. The structure was solved by direct methods (program
SHELXS97) and refined by the full-matrix least-squares method on
all F2 data using the WinGX version of SHELXL97 programs [13]. All
hydrogen atoms were located in their calculated positions (C–H
0.93–0.97 Å) and refined using a riding model. Molecular graphics
were performed using PLATON2001 [14]. A summary of the crystal
data, experimental details and refinement results are listed in
Table 1.