Synthesis and characterisation of tin(IV) and organotin(IV) derivatives 2-{[(2-hydroxyphenyl)imino]methyl}phenol

Article abstract of DOI:10.1016/S0020-1693(01)00654-5

From the interaction of 2-{[(2-hydroxyphenyl)imino]methyl}phenol(salopH₂) with tin and organotin(IV) acceptors, the derivatives [SnR₃(salopH)] (R = Me or Buⁿ), [SnR₂(salop)] (R = Me, Buⁿ, Bu^t, Vin or Ph), [SnRX(salop)(solvent)] (R = Me, Buⁿ, Ph or X; X = Cl, Br or I; solvent = CH₃OH or H₂O), [Sn(salop)₂], [R₂SnCl₂(salopH₂)] (R = Me or Buⁿ) have been obtained and characterised. The chelates, containing the Schiff base in mono or dianionic form, are generally stable both in the solid state and in solution, whereas the [SnR₂Cl₂(salopH₂)] adducts slowly decompose in acetone or DMSO yielding [SnR₂(salop)] and releasing HCl. All the [SnR₂(salop)] and [SnRX(salop)(solvent)] complexes are fluxional in solution. The ¹¹⁹Sn NMR chemical shift is a function of the number of R groups. The X-ray single crystal diffraction study of [SnVin₂(salop)] shows the metal to be five-coordinate in a distorted square pyramidal environment, Sn-C distances being 2.112(2) and 2.113(2) ?, Sn-O 2.117(2) and 2.125(2) ? and Sn-N 2.227(2) ?. The whole structure consists of molecular units connected by weak intermolecular Sn-O interactions. In the complexes [SnX₂(salop)(CH₃OH)]·CH₃OH complexes (X = Cl or Br), the tin atom is found in a strongly distorted octahedral environment with the Sn-O bond ranging from 1.995(3) to 2.055(2) ?. The Sn-N bond is 2.116(4) ? in the bromide and 2.171(3) ? in the chloride complex.

Full text of DOI:10.1016/S0020-1693(01)00654-5

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Inorganica Chimica Acta 325 (2001) 103–114
Synthesis and characterisation of tin(IV) and organotin(IV)
derivatives 2-{[(2-hydroxyphenyl)imino]methyl}phenol
Claudio Pettinari a,*, Fabio Marchetti a, Riccardo Pettinari a, Domenico Martini a,
Andrei Drozdov b, Sergei Troyanov b
a Dipartimento di Scienze Chimiche, Uni6ersita` degli Studi, 6ia S. Agostino 1, 62032 Camerino, Italy
b Department of Chemistry, Moscow State Uni6ersity, Vorobje6y Gory, 119899 Moscow, Russia
Received 2 May 2001; accepted 27 August 2001
Abstract
From the interaction of 2-{[(2-hydroxyphenyl)imino]methyl}phenol(salopH2) with tin and organotin(IV) acceptors, the deriva-
tives [SnR3(salopH)] (R=Me or Bun), [SnR2(salop)] (R=Me, Bun, But, Vin or Ph), [SnRX(salop)(solvent)] (R=Me, Bun, Ph or
X; X=Cl, Br or I; solvent=CH3OH or H2O), [Sn(salop)2], [R2SnCl2(salopH2)] (R=Me or Bun) have been obtained and
characterised. The chelates, containing the Schiff base in mono or dianionic form, are generally stable both in the solid state and
in solution, whereas the [SnR2Cl2(salopH2)] adducts slowly decompose in acetone or DMSO yielding [SnR2(salop)] and releasing
HCl. All the [SnR2(salop)] and [SnRX(salop)(solvent)] complexes are fluxional in solution. The 119Sn NMR chemical shift is a
function of the number of R groups. The X-ray single crystal diffraction study of [SnVin2(salop)] shows the metal to be
,
five-coordinate in a distorted square pyramidal environment, SnꢀC distances being 2.112(2) and 2.113(2) A, SnꢀO 2.117(2) and
,
,
2.125(2) A and SnꢀN 2.227(2) A. The whole structure consists of molecular units connected by weak intermolecular SnꢀO
interactions. In the complexes [SnX2(salop)(CH3OH)]·CH3OH complexes (X=Cl or Br), the tin atom is found in a strongly
,
,
distorted octahedral environment with the SnꢀO bond ranging from 1.995(3) to 2.055(2) A. The SnꢀN bond is 2.116(4) A in the
,
bromide and 2.171(3) A in the chloride complex. © 2001 Published by Elsevier Science B.V.
Keywords: Tin(IV) compounds; Organotin (IV) complexes; X-ray crystal structures; Schiff base
tentially ONO tridentate Schiff base ligand forming
1. Introduction
stable complexes with many transition and post-transi-
tion metal ions [5]. Its coordination chemistry is less
developed with respect to that of tetradentate Schiff
bases as N,N%-ethylenbis(salicylaldimine) (salenH2) [6].
Literature on metal–salopH2 complexes of the
Group IV elements is rather sparse [7], only three
tin(IV) complexes structurally characterised being re-
ported, i.e [SnMe2(Salop)] [8], [SnPh2(salop)] [9] and
[Sn(salop)]2 [10]. In addition, the organotin(IV) deriva-
tives reported have not been fully spectroscopically
characterised. As a part of our project dealing with the
study of the interaction of tin(IV) and organotin(IV)
species with O-donor and N-donor ligands, we report
here synthesis and full characterisation of 15 new
derivatives containing the schiff base in mono- (sa-
lopH)−, di-anionic(salop)2− or neutral form (salopH2).
We described here also a new route for the synthesis
Schiff bases still play an important role as ligands in
metal coordination chemistry even after almost a cen-
tury since their discovery [1]. Recently, this class of
molecules has been employed as models for biological
systems [2] and in the control of the stereochemistry in
six-coordinate [(Schiff base)MCl2] complexes (M=Ti
or Zr) which are potential catalysts for alkene poly-
merisation [3]. Increasing attention has also been
devoted to Schiff base complexes of organotin(IV) moi-
eties in view of their potential applications in medicinal
chemistry and biotechnology [4]. 2-{[(2-Hydrox-
yphenyl)imino]methyl}phenol(salopH2) is a typical po-
* Corresponding author. Tel.: +39-0737-402 217; fax: +39-0737-
637 345.
E-mail addresses: pettinar@camserv.unicam.it (C. Pettinari), droz-
dov@inorg.chem.msu.ru (A. Drozdov).
0020-1693/01/$ - see front matter © 2001 Published by Elsevier Science B.V.
PII: S0020-1693(01)00654-5

104
C. Pettinari et al. / Inorganica Chimica Acta 325 (2001) 103–114
and not-reported spectroscopic features of [SnMe2-
(salop)] [8], [SnPh2(salop)] [9] and [Sn(salop)2] [10], as
well as the X-ray crystal structure of [SnVin2(salop)],
surements (\M, reported as V−1 cm2 mol−1) of
dichloromethane solutions of complexes 1–18 were
taken with a Crison CDTM 522 conductimeter at r.t.
[SnCl2(salop)(CH3OH)]·CH3OH,
OH)]·CH3OH.
[SnBr2(salop)(CH3-
2.3. Synthesis of the donor salopH2
The 2-{[(2-hydroxyphenyl)imino]methyl}phenol (Fig.
1) has been synthesised by stirring at 60–80 °C a 1:1
molar ratio mixture of salicylaldehyde and 2-hydrox-
yaniline in refluxing methanol following a reported
method [11]. M.p. 187–189 °C. IR (Nujol, cm−1):
2300br, 1800br (OH), 1631s, 1612s, 1593s, 1530s, 1506w
2. Experimental
2.1. Materials
All chemicals and reagents were reagent grade qual-
ity and were used as received without further purifica-
tion. Solvent evaporations were always carried out
under vacuum by using a rotavaporator. The samples
for microanalysis were dried in vacuo to constant
weight (20 °C, ca. 0.1 Torr). All syntheses were carried
out under a nitrogen atmosphere. Hydrocarbon sol-
vents were dried by distillation from sodium–potas-
sium; dichloromethane was distilled from calcium
hydride; benzene and light petroleum (40–60 °C) were
dried by refluxing over freshly cut sodium; methanol
was dried over CaO. All solvents were degassed with
dry nitrogen prior to use.
1
(C···C, C···N). H NMR (CDCl3, 293 K): l, 5.84, 12.28
(s br, OH) 6.93–7.46 (m, 8H, Haromatic), 8.66 (m, 1H,
1
CH). H NMR (acetone-d6, 293 K): l, 6.88–7.56 (m,
1
8H, Haromatic), 8.56 (s br, OH), 8.92 (m, 1H, CH). H
NMR (DMSO-d6, 293 K): l, 6.82–7.62 (m, 8H,
H
aromatic), 8.95 (m, 1H, CH), 11.10 (s br, OH). 13C
NMR (CDCl3, 293 K): l, 117.3, 128.7, 119.5, 121.0,
135.9, 119.3, 115.9, 133.7, 118.3, 132.6 (s, Caromatic),
149.9, 160.6 (s, CO), 163.9 (s, CN). 13C NMR (acetone-
d6, 293 K): l, 118.8, 130.0, 121.8, 122.2, 138.1, 120.9,
118.5, 134.9, 120.8, 134.6 (s, Caromatic), 152.9, 163.2 (s,
CO), 165.0 (s, CN). 13C NMR (DMSO-d6, 293 K): l,
116.7, 128.1, 119.6, 119.5, 134.9, 119.5, 116.5, 132.9,
119.6, 132.3 (s, Caromatic), 151.1, 160.7 (s, CO), 161.7 (s,
CN). UV (CHCl3, umax, nm): 243, 270, 354.
2.2. Physical measurements
2.4. Synthesis of complexes
Elemental analyses (C, H, N) were performed in-
house with a Fison’s instruments 1108 CHNS-O ele-
mental analyser. IR spectra were recorded from 4000 to
100 cm−1 with a Perkin–Elmer system 2000 FT-IR
instrument. 1H, 13C and 119Sn NMR spectra were
recorded on a VXR-300 Varian instrument and on a
Bruker AC 200 spectrometers operating at room tem-
2.4.1. [SnMe2(salop)] (1)
To a hot methanol solution (30 ml) of the Schiff base
salopH2 (0.42 g, 2.0 mmol), sodium methoxide was
added (0.21 g, 4.0 mmol). When the colour of the
solution changed from orange to red, SnMe2Cl2 (0.42 g,
2.0 mmol) was added. After 3 h stirring, the solvent was
removed and the residue was treated with chloroform
(15 ml). The solution formed was filtered off to remove
the sodium salt and then evaporated to dryness. The
red powder was re-crystallised from diethyl ether and
shown to be compound 1. Yield 54%. M.p. 169−
170 °C. Anal. Calc. for C15H15NO2Sn: C, 50.05; H,
4.20; N, 3.89. Found: C, 49.88; H, 4.30; N, 3.76%. IR
(Nujol, cm−1): 3059w (CH), 1606s, 1585s, 1567sh,
1530s, 1514m (C···C, C···N), 528s, 520m (SnꢀO), 573m,
1
perature (r.t.) (at 300 and 200 MHz for H; 75 and 50
MHz for 13C; and 111.9 MHz for 119Sn). The chemical
shifts (l) are reported in parts per million (ppm) from
SiMe4 (1H and 13C calibration by internal deuterium
solvent lock) and SnMe4 (external). The spectral width
is 900 ppm (from +200 to −700 ppm). Peak multi-
plicities are abbreviated: singlet, s; doublet, d; triplet, t;
multiplet, m. UV spectra were recorded on a HP-8453
spectrometer. Melting points are uncorrected and were
taken on an SMP3 Stuart scientific instrument and on a
capillary apparatus. The electrical conductivity mea-
1
545w (SnꢀC), 321s (SnꢀN). H NMR (CDCl3, 293 K):
2
2
l, 0.8 (s, 6H, J(119Snꢀ1H): 78.1 Hz, J(117Snꢀ1H): 74.8
Hz, SnꢀCH3) 6.6–6.8 (m), 7.1–7.5 (m) (8H, Haromatic),
8.7 (s, 1H, 3J(119/117Snꢀ1H): 50.6 Hz, CHsalop). 13C
NMR (CDCl3, 293 K): l, 0.99 (s, J(119Snꢀ13C): 660
1
Hz, SnꢀCH3), 114.66, 116.59, 117.26, 117.79, 118.47,
122.56, 130.24, 135.22, 136.84, 137.12 (s, Caromatic),
158.84, 168.85 (s, CO), 161.98 (s, CN). 119Sn NMR
(CDCl3, 293 K): l, −146.4. UV (CHCl3, umax, nm):
249, 316, 455. \M (DMSO, c (mol l−1)=1.0×
10−3)=1.3 V−1 cm2 mol−1. \M (CH2Cl2, c (mol
Fig. 1. Structure of the Schiff base salopH2.
l .
−1)=0.9×10−3)=0.1 V−1 cm2 mol−1

C. Pettinari et al. / Inorganica Chimica Acta 325 (2001) 103–114
105
2.4.2. [SnBun2(salop)] (2)
\
(DMSO, c (mol l−1)=0.9×10−3, V−1 cm2
M
Complex 2 (orange) was prepared as 1. Yield 44%.
M.p. 131 °C dec. Anal. Calc. for C21H27NO2Sn: C,
56.79; H, 6.13; N, 3.15. Found: C, 56.63; H, 5.97; N,
3.26%. IR (Nujol, cm−1): 3053w (CH), 1607s, 1589sh,
1538m, 1509w (C···C, C···N), 504vs, 475s (SnꢀO), 578s,
mol−1)=0.5.
\
(CH2Cl2, c (mol l
−1)=1.1×
M
10−3)=0.2 V−1 cm2 mol−1
.
2.4.5. [SnPh2(salop)] (5)
To a hot ethanol solution (30 ml) of salopH2 (2.0
mmol), NaOMe was added (4.0 mmol). After the
colour of the solution changed from orange to red.
After a few minutes Ph2SnCl2 (2.0 mmol) was added
and a red precipitate immediately formed. After 3 h
stirring, the solid was filtered off, washed with ethanol,
dried under reduced pressure to constant weight and
shown to be compound 5. Yield 70%. M.p. 200–
201 °C. Anal. Calc. for C25H19NO2Sn: C, 62.02; H,
3.96; N, 2.89. Found: C, 62.25; H, 4.06; N, 3.02%. IR
(Nujol, cm−1): 3047w (CH), 1605s, 1590s, 1567sh,
1539s, 1506w (C···C, C···N), 605s, 536vs (SnꢀO), 262m,
243m (SnꢀC), 334 (SnꢀN). 1H NMR (CDCl3, 293 K): l,
6.7–7.5 (m, 8H, Haromatic of salop), 7.9–8.0 (m, 10H,
1
534m (SnꢀC), 324m (SnꢀN). H NMR (CDCl3, 293 K):
l, 0.9–1.1 (m), 1.7–1.8 (m) (18H, SnꢀBun), 6.7–7.4 (m,
8H, Haromatic), 8.6 (s, 1H, 3J(119/117Snꢀ1H): 44.8 Hz,
CHsalop
)
13C NMR (CDCl3, 293 K): l, 13.49 (s,
SnꢀBun), 26.37, 26.47, 26.58 (s, SnꢀBun), 116.69,
118.02, 118.32, 119.39, 121.18, 129.10, 133.00, 134.56,
136.30, 149.87 (s, Caromatic) 159.43, 162.11 (s, CO),
163.35 (s, CN). 119Sn NMR (CDCl3, 293 K): l, −
186.4. UV (CHCl3, umax, nm): 249, 318, 454. \M
(CH2Cl2, c (mol l−1)=1.0×10−3)=0.1 V−1 cm2
mol−1
.
2.4.3. [SnBut2(salop)] (3)
3
Complex 3 was prepared as 1 by using 2.0 mmol of
salopH2, 4.0 mmol of NaOMe and 2.0 mmol of
SnBut2Cl2. Yield 45%. M.p. 127–129 °C. Anal. Calc.
for C21H27NO2Sn: C, 56.79; H, 6.13; N, 3.15. Found:
C, 56.55; H, 6.22; N, 3.03%. IR (Nujol, cm−1): 3050w
(CH), 1605s, 1584s, 1559sh, 1533s (C···C, C···N), 525s
3J(119/117Snꢀ1H): 92.0 Hz, SnꢀC6H5), 8.7 (s, 1H, J(119/
117Snꢀ1H): 59.6 Hz, CHsalop). 13C NMR (CDCl3, 293
K): l, 114.63, 116.86, 117.50, 119.04, 122.81, 125.05,
125.25, 127.84, 128.67, 129.50, 129.72, 130.12, 130.29,
131.13, 131.83, 135.09, 135.38, 136.04, 136.59, 137.00,
137.14, 139.70 (s, Csalop+SnꢀC6H5). 158.96, 169.47 (s,
CO), 161.57 (s, CN). 119Sn NMR (CDCl3, 293 K): l,
−328.35. UV (CHCl3, umax, nm): 246, 318, 454. \M
(DMSO, c (mol l−1)=1.0×10−3, V−1 cm2 mol−1)=
0.2. \M (CH2Cl2, c (mol l−1)=1.1×10−3)=0.1 V−1
1
(SnꢀO), 488m, 441w (SnꢀC), 318m (SnꢀN). H NMR
(CDCl3, 293 K): l, 1.30 (s, 18H, SnꢀBut, J(119Snꢀ1H):
3
108.4 Hz, 3J(117Snꢀ1H): 104.3 Hz), 6.6–7.4 (m, 8H,
Haromatic), 8.7 (s, 1H, 3J(119/117Snꢀ1H): 41.9 Hz, CHsalop).
13C NMR (CDCl3, 293 K): l, 29.85 (s, SnꢀC(CH3)3),
40.68 (s, SnꢀC(CH3)3), 114.67, 115.84, 116.44, 118.49,
122.57, 129.81, 132.23, 135.00, 136.47, 160.36 (s,
Caromatic), 161.34 (s, CN), 160.36, 170.66 (s, CO). 119Sn
cm2 mol−1
.
2.4.6. [SnCl2(Salop)(H2O)] (6)
Complex 6 was prepared in methanol as 5 by using
2.0 mmol of salopH2, 4.0 mmol of NaOMe and 2.0
mmol of SnCl4·5H2O. Yield 74%. M.p. 290 °C dec.
Anal. Calc. for C13H11Cl2NO3Sn: C, 37.28; H, 2.65; N,
3.34. Found: C, 37.20; H, 2.73; N, 3.46%. IR (Nujol,
cm−1): 3000–3400 (H2O), 1608s, 1590w, 1557w,
1544m, 1508w (C···C, C···N), 502s, 490s (SnꢀO), 377sh,
NMR (CDCl3, 293 K): l, −279.2. UV (CHCl3, umax
,
nm): 248, 465. \M (CH2Cl2, c (mol l−1)=1.0×
10−3)=0.3 V−1 cm2 mol−1
.
2.4.4. [SnVin2(salop)] (4)
Complex 4 was prepared as 2 by using 2.0 mmol of
salopH2, 4.0 mmol of NaOMe and 2.0 mmol of
SnVin2Cl2. Yield 31%. M.p. 133–134 °C. Anal. Calc.
for C17H15NO2Sn: C, 53.17; H, 3.94; N, 3.65. Found:
C, 53.04; H, 4.02; N, 3.76%. IR (Nujol, cm−1): 3050w
(CH), 1605s, 1584s, 1567sh, 1535s (C···C, C···N), 519vs,
489m (SnꢀO), 557s, 539m (SnꢀC), 328m (SnꢀN). 1H
NMR (CDCl3, 293 K): l, 6.14 (dd) 6.22 (dd) 6.30 (dd)
1
366s, 348sh (SnꢀCl). H NMR (acetone-d6, 293 K): l,
6.8–7.0 (m) 7.2–7.3 (m) 7.4–7.9 (m) (8H, Haromatic), 8.9
(br, 2H, H2O), 9.2 (s, 1H, CHsalop, 3J(119/117Snꢀ1H): 86.7
Hz). 119Sn NMR (CDCl3, 293 K): l, −563.37. UV
(CHCl3, umax, nm): 246, 315, 426. \M (DMSO, c (mol
l
−1)=1.1×10−3)=4.6 V−1 cm2 mol−1. \M (CH2Cl2,
c (mol l−1)=1.0×10−3)=0.3 V−1 cm2 mol−1
.
(6H, J(1Hꢀ1H)gem
:
3.6 Hz, J(1Hꢀ1H)cis: 11.8 Hz,
J(1Hꢀ1H)trans: 19.9 Hz, SnꢀCHꢁCH2), 6.7–7.0 (m) 7.2–
2.4.7. [SnCl2(salop)(CH3OH)]·CH3OH (7)
7.5 (m) (8H, Haromatic), 8.6 (s, 1H, J(119/117Snꢀ1H): 55.8
Complex 7 was obtained from the mother liquor of
complex 6. M.p. 300 °C dec. Anal. Calc. for
C15H17Cl2NO4Sn: C, 38.75; H, 3.69; N, 3.01. Found: C,
38.64; H, 3.46; N, 3.18%. IR (Nujol, cm−1): 3000–3400
(OH), 1607s, 1591w, 1559w, 1543m, 1507w (C···C,
C···N), 501s, 482s (SnꢀO), 367m, 353s, 335s (SnꢀCl). 1H
NMR (acetone-d6, 295 K): l, 3.3 (s, 3H, CH3OH),
6.8–7.0 (m) 7.2–7.3 (m) 7.4–7.9 (m) (8H, Haromatic), 8.9
3
Hz, CHsalop). 13C NMR (CDCl3, 293 K): l, 114.67,
116.84, 117.46, 118.75, 122.61, 130.29, 131.10, 136.96,
138.50, (s, Caromatic), 135.30 (s, 2J(117/119Snꢀ13C): 442
Hz, SnꢀCHꢁCH2), 136.77 (s, 1J(119Snꢀ13C): 975 Hz,
1J(117Snꢀ13C): 930 Hz, SnꢀCHꢁCH2), 161.59 (s, CN),
169.28, 158.84 (s, CO). 119Sn NMR (CDCl3, 293 K): l,
−320.69. UV (CHCl3, umax, nm): 248, 291, 317, 454.

106
C. Pettinari et al. / Inorganica Chimica Acta 325 (2001) 103–114
(br, 1H, CH3OH), 9.2 (s, 1H, CHsalop 3J(119/117Snꢀ1H):
84.2 Hz). 119Sn NMR (CDCl3, 295 K): l, −542.74,
−558.10. 119Sn NMR (acetone-d6, 295 K): l, −545br,
−562br. \M (DMSO, c (mol l−1)=1.0×10−3)=4.0
V−1 cm2 mol−1. \M (CH2Cl2, c (mol l−1)=1.1×
316, 436. Complex 10 can also be obtained by interac-
tion of 2.0 mmol of salopH2 with 2.0 mmol of SnI4 in
refluxing toluene without base. \M (DMSO, c (mol
l
−1)=1.0×10−3)=44.8 V−1 cm2 mol−1
.
\
M
(CH2Cl2, c (mol l−1)=1.0×10−3)=0.5 V−1 cm2
mol−1
10−3)=0.2 V−1 cm2 mol−1
.
.
2.4.8. [SnBr2(salop)(H2O)] (8)
2.4.11. [SnMeCl(salop)(H2O)] (11)
Complex 8 was prepared as 6 by using 2.0 mmol of
salopH2, 4.0 mmol of NaOMe and 2.0 mmol of SnBr4.
Yield 76%. M.p. 218 °C dec. Anal. Calc. for
C13H11Br2NO3Sn: C, 30.75; H, 2.18; N, 2.76. Found: C,
30.54; H, 2.22; N, 2.84%. IR (Nujol, cm−1): 3000–3400
(H2O), 1605s, 1589sh, 1557w, 1543s, 1519w, 1503w
(C···C, C···N), 501s, 485s (SnꢀO), 234s, 200vs (SnꢀBr).
1H NMR (CDCl3, 294 K): l, 3.45 (s br, 2H, H2O),
6.8–7.1 (m) 7.2–7.5 (m) (8H, Haromatic), 8.57 (s, 1H,
CHsalop 3J(119/117Snꢀ1H): 76.6 Hz). 119Sn NMR (ace-
tone-d6, 293 K): l, −755.1. UV (CHCl3, umax, nm):
245, 315, 429. \M (DMSO, c (mol l−1)=1.1×
10−3)=21.5 V−1 cm2 mol−1. \M (CH2Cl2, c (mol
Complex 11 was obtained as 2 by using 2.0 mmol of
salopH2, 4.0 mmol of NaOMe and 2.0 mmol of
SnMeCl3. Yield 32%. M.p. \350 °C. Anal. Calc. for
C14H14ClNO3Sn: C, 42.11; H, 3.54; N, 3.51. Found: C,
42.46; H, 3.48; N, 3.23%. IR (Nujol, cm−1): 3000–
3400br (H2O), 1606s, 1586s, 1539s (C···C, C···N), 579w
1
(SnꢀC), 497m, 487s (SnꢀO), 269vs (SnꢀCl). H NMR
(acetone-d6, 293 K): l, 0.95 (s, 3H, SnꢀCH3,
2
2J(119Snꢀ1H): 122.1 Hz, J(117Snꢀ1H): 111.0 Hz), 3.47
(s, 3H, CH3OH), 6.7–7.8 (m, 8H, Haromatic), 9.03 (s, 1H,
3J(119/117Snꢀ1H): 91.7 Hz, CHsalop). 13C NMR (acetone-
d6, 293 K): l, 115.80, 117.30, 117.88, 119.06, 121.25,
123.14, 126.76, 130.21, 132.99, 136.06, 137.69 (s,
Caromatic), 157.34, 168.69, 173.73, (s, CO), 159.76 (s,
CN), resonance of SnꢀCH3 not observed. 13C NMR
(CDCl3, 293 K): l, 115.8, 117.29, 117.88, 119.06,
119.31, 121.24, 123.14, 126.76, 130.21, 130.73, 132.99,
136.06, 136. (s, Caromatic), 168.69, 157.34 (s, CO), 159.76
(s, CN). 119Sn NMR (DMSO-d6, 293 K): l, −436.44,
−442.54. UV (CHCl3, umax, nm): 252, 286, 312, 430.
l
−1)=1.1×10−3)=0.1 V−1 cm2 mol−1
.
2.4.9. [SnBr2(salop)(CH3OH)]·CH3OH (9)
Complex 9 was obtained from the mother liquor of
complex 8. M.p. 230 °C dec. Anal. Calc. for
C14H13Br2NO3Sn: C, 32.53; H, 3.09; N, 2.51. Found: C,
32.44; H, 3.12; N, 2.72%. IR (Nujol, cm−1): 3000–3400
(OH), 1605s, 1590sh, 1558w, 1544s, 121w, 1504w
(C···C, C···N), 502s, 497w, 483s (SnꢀO), 226s, 203vs
\
(DMSO, c (mol l−1)=1.1×10−3)=2.2 V−1 cm2
M
mol−1. \M (CH2Cl2, c (mol l−1)=1.0×10−3)=0.4
1
(SnꢀBr). H NMR (acetone-d6, 293 K): l, 3.36 (s, 3H,
V−1 cm2 mol−1
.
CH3OH), 6.8–7.0 (m) 7.2–7.3 (m) 7.4–7.9 (m) (8H,
Haromatic), 9.22 (s, 1H, CHsalop
,
3J(119/117Snꢀ1H): 75.5
2.4.12. [SnBunCl(salop)(CH3OH)] (12)
Hz). 119Sn NMR (CDCl3, 293 K): l, −756.58. \M
(DMSO, c (mol l−1)=1.0×10−3)=21.9 V−1 cm2
mol−1. \M (CH2Cl2, c (mol l−1)=1.2×10−3)=0.1
To a hot methanol solution (30 ml) of salopH2 (0.21
g, 1.0 mmol), SnBunCl3 (0.56 g, 2.0 mmol) was added
and a yellow precipitate immediately formed. After 8 h
stirring, the solid was filtered off, washed with
methanol and shown to be compound 12. Yield 96%.
M.p. 233–235 °C. Anal. Calc. for C18H22ClNO3Sn: C,
47.57; H, 4.88; N, 3.08. Found: C, 47.74; H, 4.68; N,
3.20%. IR (Nujol, cm−1): 3000–3400br (OH), 1605s,
1588s, 1568sh, 1539s (C···C, C···N), 584w (SnꢀC),
494m, 481s (SnꢀO), 283s, 275s (SnꢀCl). 1H NMR
(CDCl3, 293 K): l, 0.96, 1.00, 0.9–1.1 (t, 3H, SnꢀBun),
1.4–1.6 (m) 1.9–2.1 (m) (6H, Sn–Bun), 3.49 (s, 3H,
CH3OH), 6.7–7.4 (m, 8H, Haromatic), 8.41 (s, 1H,
V−1 cm2 mol−1
.
2.4.10. [SnI2(salop)(CH3OH)] (10)
Complex 10 was prepared as 6, by using 2.0 mmol of
salopH2, 4.0 mmol of NaOMe and 2.0 mmol of SnI4.
Yield 85%. M.p. \350 °C. Anal. Calc. for
C14H13I2NO3Sn: C, 27.31; H, 2.13; N, 2.28. Found: C,
27.56; H, 2.20; N, 2.40%. IR (Nujol, cm−1): 3000–3400
(CH3OH), 1602s, 1588s, 1543s (C···C, C···N), 508m,
1
481s (SnꢀO), 178s, 143m (SnꢀI). H NMR (CDCl3, 293
3
K): l, 3.51 (s, 3H, CH3OH), 6.8–7.8 (m, 8H, Haromatic),
CHsalop 3J(119Snꢀ1H): 85.1 Hz, J(117Snꢀ1H): 81.4 Hz).
3
8.50 (br, 1H, CH3OH), 8.93 (s, 1H, J(119Snꢀ1H): 86.7
13C NMR (DMSO-d6, 293 K): l, 13.56 (s, SnꢀBun),
26.02 (s, SnꢀBun), 27.41 (s, SnꢀBun 2J(119/117Snꢀ13C):
Hz; 3J(117Snꢀ1H): 82.0 Hz, CHsalop). 13C NMR
(DMSO-d6, 293 K): l, 48.59 (s, CH3OH) 116.00,
116.28, 117.63, 117.99, 118.52, 119.03, 119.19, 119.46,
119.84, 121.93, 128.77, 129.27, 130.57, 130.68, 136.78,
137.16, 153.56, 154.02, 154.16, 154.49 (s, Caromatic),
166.40, 165.85, 165.17, 164.42 (s, CO), 162.84, 162.34
(s, CN). 119Sn NMR (DMSO-d6): l, −620.9, −622.6,
−813.94, −814.99. UV (CHCl3, umax, nm): 245, 286,
1
59.7 Hz), 29.64 (s, SnꢀBun, J(119Snꢀ13C): 1138.2 Hz,
1J(117Snꢀ13C): 1070.9 Hz), 50.87 (s, CH3OH), 113.88,
118.48, 119.34, 120.00, 123.01, 130.38, 134.17, 135.93 (s,
C
aromatic), 154.97, 164.58 (s, CO), 159.03 (s, CN). 119Sn
NMR (DMSO-d6, 293 K): l, −452.32. UV (CHCl3,
umax, nm): 246, 313, 431. \M (DMSO, c (mol l−1)=
1.0×10−3)=1.1 V−1 cm2 mol−1. \M (CH2Cl2, c (mol

C. Pettinari et al. / Inorganica Chimica Acta 325 (2001) 103–114
107
l
−1)=0.9×10−3)=0.2 V−1 cm2 mol−1. Compound
C16H19NO2Sn: C, 51.25; H, 4.84; N, 3.73. Found: C,
51.38; H, 4.92; N, 3.85%. IR (Nujol, cm−1): 3061w
(CꢀH), 1606s, 1586s, 1565sh, 1530s, 1512w (C···C,
C···N), 571s, 528s, 520s (SnꢀC), 486s, 458s br (SnꢀO).
1H NMR (CDCl3, 293 K): l, 0.56 (s, 9H, SnꢀCH3,
12 has been obtained also from the reaction of
SnBunCl3 with salopH2 in refluxing toluene, in absence
of base.
2
2.4.13. [SnPhCl(salop)(CH3OH)] (13)
2J(119Snꢀ1H): 57.2 Hz, J(117Snꢀ1H): 55.0 Hz), 6.6–7.3
Complex 13 was prepared as 2 by using 2.0 mmol of
salopH2, 4.0 mmol of NaOMe and 2.0 mmol of
SnPhCl3. Yield 93%. M.p. \350 °C. Anal. Calc. for
C20H18ClNO3Sn: C, 50.63; H, 3.82; N, 2.95. Found: C,
50.38; H, 3.88; N, 3.06%. IR (Nujol, cm−1): 3000–
3400br (OH), 1606s, 1586s, 1538s (C···C, C···N), 485sbr
(m, 8H, Haromatic), 8.67 (s, 1H, CHSalop), 6.05, 12.14,
14.02 (s br, 1H, OH+NH). 13C NMR (CDCl3, 293 K):
1
l, −2.70(s, J(119/117Snꢀ13C): 400 Hz, SnꢀCH3), 114.8,
119.52, 120.28, 128.1, 131.30, 131.97, 132.69, 133.77,
136.88 (s, Caromatic), 163.67, 161.49 (s, CO), 162.03 (s,
CN). 119Sn NMR (CDCl3, 293 K): l, +50.8. \M
(CH2Cl2, c (mol l−1)=1.0×10−3)=0.05 V−1 cm2
mol−1. UV (CHCl3, umax, nm): 244, 323, 335, 361, 453.
1
(SnꢀO), 278vs (SnꢀCl), 243s (SnꢀC). H NMR (CDCl3,
293 K): l, 3.48 (s, 3H, CH3OH), 6.7–7.6 (m, 13H,
CHsalop+SnꢀPh), 8.91 (s, 1H, CHsalop, J(119/117Snꢀ1H):
3
1
88.0 Hz). H NMR (DMSO-d6, 293 K): l, 3.41 (s, 3H,
2.4.16. [SnBun3 (salopH)] (16)
CH3OH), 6.6–8.0 (m, 13H, CHsalop+SnꢀPh), 8.97,
9.07 (br, 1H, CHsalop). 13C NMR (DMSO-d6, 293 K): l,
48.61 (s, CH3OH), 115.67, 115.83, 116.04, 116.26,
116.88, 117.58, 117.82, 118.21, 118.46, 121.92, 122.21,
127.40, 128.48, 129.11, 129.33, 129.60, 130.40, 134.74,
134.87, 135.12, 135.51, 135.68, 136.02, 146.22 (s,
Complex 16 was prepared as 1 by using 2.0 mmol of
salopH2, 2.0 mmol of NaOMe and 2.0 mmol of
SnBun3Cl. Yield 72%. M.p. 128–130 °C. Anal. Calc. for
C25H37NO2Sn: C, 59.78; H, 7.43; N, 2.79. Found: C,
59.53; H, 7.56; N, 2.64%. IR (Nujol, cm−1): 3058w
w(CH), 1617s, 1589s, 1565sh, 1531m (C···C, C···N),
1
C
salop+SnꢀPh), 150.01, 154.82, 156.38, 165.75, 167.42
569m, 526br w(SnꢀC), 472s, 457s w(SnꢀO). H NMR
(s, CO), 157.21, 158.53 (s, CN). 119Sn NMR (DMSO-d6,
293 K): l, −497.40, −508.04, −571.96. UV (CHCl3,
umax, nm): 247, 286, 315, 431. \M (DMSO, c (mol
(CDCl3, 293 K): l, 0.8–1.0 (m, 9H, SnꢀBun), 1.1–1.8
(m, 18H, SnꢀBun), 6.6–7.4 (m, 8H, Haromatic), 8.66, 8.84
(s, 1H, CHsalop), 5.90, 12.15, 14.05, (s br, 1H, OHsalopH
and/or NHsalopH). 13C NMR (CDCl3, 293 K): l, 13.06
(s, SnꢀBun), 16.40 (s, SnꢀBun), 27.10 (s, 2J(119/
117Snꢀ13C): 45.8 Hz, SnꢀBun), 27.73 (s, SnꢀBun),
114.83, 116.06, 116.33, 116.94, 117.34, 117.61, 117.93,
118.97, 119.64, 119.87, 120.79, 121.42, 122.50, 127.65,
130.09, 131.73, 132.43, 133.52, 133.76, 135.23, 136.73,
137.03, 139.18 (s, Caromatic), 155.68, 159.53, 161.86,
166.46, 196.63 (s, CO), 162.22, 169.51 (s, CN). 119Sn
NMR (CDCl3, 293 K): l, +123.3. \M (CH2Cl2, c (mol
l
−1)=1.1×10−3)=1.9 V−1 cm2 mol−1. \M (CH2Cl2,
c (mol l−1)=1.0×10−3)=0.2 V−1 cm2 mol−1. Com-
pound 13 has been also obtained by the reaction of
SnPhCl3 with salopH2 in methanol, in the absence of
base.
2.4.14. [Sn(salop)2] (14)
Complex 14 was prepared as 2 by using 2.0 mmol of
SalopH2, 4.0 mmol of NaOMe and 1.0 mmol of SnBr4,
or by using 2.0 mmol of SalopH2, 4.0 mmol of NaOMe
and 1.0 mmol of SnCl4·H2O or by using 2.0 mmol of
SalopH2, 4.0 mmol of NaOMe and 2.0 mmol of
Vin2SnCl2. Yield 74%. M.p. \350 °C. Anal. Calc. for
C26H18N2O4Sn: C, 57.71; H, 3.35; N, 5.18. Found: C,
57.53; H, 3.41; N, 5.30%. IR (Nujol, cm−1): 1605s,
1586s, 1538s, 1506w (C···C, C···N), 495m, 485s (SnꢀO).
1H NMR (CDCl3, 293 K): l, 6.8–7.0 (m), 7.2–7.6 (m)
l
−1)=1.0×10−3)=0.05 V−1 cm2 mol−1
.
2.4.17. SnMe2Cl2(salopH2)] (17)
To a diethyl ether solution (30 ml) of salopH2 (0.21
g, 1.0 mmol), SnMe2Cl2 (1.75 g, 8.0 mmol) was added,
and a yellow precipitate immediately formed. After 8 h
stirring, the solid was filtered off, washed with diethyl
ether and shown to be compound 17. Yield 88%. M.p.
174–177 °C. Anal. Calc. for C15H17Cl2NO2Sn: C,
42.90; H, 4.50; N, 3.13. Found: C, 42.74; H, 4.54; N,
3.24%. IR (Nujol, cm−1): 1633sbr, 1595s, 1528w, 1505s
(C···C, C···N), 576s, 567s (SnꢀC), 496sbr, 478s (SnꢀO),
3
(16H, Haromatic), 8.90 (s, 2H, J(119/117Snꢀ1H): 86.7 Hz,
CHsalop). 13C NMR (CDCl3, 293 K): l, 114.55, 118.40,
119.01, 110.50, 123.59, 135.99, 137.25 (s, Csalop); the CN
and CO resonance were not observed. \M (DMSO, c
(mol l−1)=1.0×10−3)=1.3 V−1 cm2 mol−1. \M
(CH2Cl2, c (mol l−1)=1.1×10−3)=0.2 V−1 cm2
1
299br (SnꢀCl). H NMR (DMSO-d6, 293 K): l, 1.02 (s,
6H, 2J(119Snꢀ1H): 114.7 Hz, 2J(117Snꢀ1H): 109.9 Hz,
mol−1
.
119Sn NMR (CDCl3, 293 K): l, −567.94. UV
CH3), 6.8ꢀ7.5 (m, 8H, Haromatic), 9.13 (s, 1H, CHsalopH ),
2
(CHCl3, umax, nm): 247, 319, 436.
10.24, 10.74 (s br, OHsalopH and/or NHsalopH ). 13C
2
2
1
NMR (DMSO-d6, 293 K): l, 23.88 (s, J(119/117Snꢀ1H):
931.0 Hz, SnꢀCH3), 136.46, 134.62, 133.31, 132.16,
129.12, 124.23, 122.32, 119.17, 118.32, 116.72, (s,
Carom), 150.82, 161.07, 161.72, 191.65 (s, CO and CN).
119Sn NMR (DMSO-d6, 293 K): l, −241.55. \M
2.4.15. [SnMe3(salopH)] (15)
Derivative 15 was prepared as 2 by using 2.0 mmol of
salopH2, 2.0 mmol of NaOMe and 2.0 mmol of
SnMe3Cl. Yield 65%. M.p. 141–144 °C. Anal. Calc. for

108
C. Pettinari et al. / Inorganica Chimica Acta 325 (2001) 103–114
Table 1
Crystallographic data, details of data collection and refinement for complexes 4, 7 and 9
Compound
[SnVI2(salop)] (4)
[SnCI2(salop)(CH3OH)]·CH3OH (7)
[SnBr2(salop)(CH3OH)]·CH3OH (9)
Molecular formula
M
C17H15NO2Sn
383.99
C15H17C12NO4Sn
464.87
C15H17Br2NO4Sn
553.79
Crystal system
Space group
triclinic
triclinic
triclinic
(
(
(
P1
P1
P1
,
a (A)
7.597(2)
10.203(2)
10.378(2)
103.40(3)
94.56(3)
103.16(2)
754.5(3)
2
7.642(2)
9.162(2)
12.897(3)
92.42(3)
95.99(3)
106.11(3)
860.4(4)
2
7.638(2)
9.330(3)
13.080(4)
93.91(4)
96.05(4)
105.15(4)
890.2(5)
2
,
b (A)
,
c (A)
h (°)
i (°)
k (°)
3
,
V (A )
Z
Dcalc (Mg m−3
)
1.690
16.96
1.794
18.13
2.066
59.41
v (cm−1
)
Temperature (K)
q (max) (°)
180(2)
26.8
180(2)
26.8
180(2)
27.0
Number of reflections collected
Numberof unique reflections
Reflections with I\2|(I)
Reflections/parameters in refinement
wR2(all)
5751
2902
2751
2875/250
0.0572
0.0223
4869
3267
2574
2776/218
0.0623
0.0235
7491
3450
2745
3016/236
0.0688
0.0282
R1 (I\2|(I))
(DMSO, c (mol l−1)=1.0×10−3)=0.05 V−1 cm2
mol−1. UV (CHCl3, umax, nm): 243, 270, 354.
graphite monochromated Mo Ka radiation. Numerical
absorption correction was only applied for structure 9
due to the higher absorption coefficient. The structures
were solved by direct methods (SHELXS-86) [12] and
refined anisotropically for all non-hydrogen atoms us-
ing crystallographic program package SHELXL-93 [13].
Hydrogen atoms of vinyl groups in 4 and that of OH
group in methanol molecules in both 7 and 9 were
located from the difference Fourier maps and refined
isotropically. All other H atoms were included in the
calculated positions and refined in a riding mode. In the
structure 9, the bridging N and C(7) atoms of the salop
ligand were found to be disordered between two posi-
tions with occupancy ratio 80:20, which corresponds to
the disorder of the whole salop ligand. The compara-
2.4.18. [SnBun2 Cl2(salopH2)] (18)
Complex 18 was prepared as 17 by using 1.0 mmol of
salopH2 and 5.0 mmol of SnBun 2Cl2. Yield 76%. M.p.
192–194 °C. Anal. Calc. for C21H29Cl2NO2Sn: C,
48.78; H, 5.65; N, 2.71. Found: C, 48.43; H, 5.58; N,
2.55%. IR (Nujol, cm−1): 3193br (H2O), 1626s, 1590s,
1508s (C···C, C···N), 577s, 533m (SnꢀC), 502sbr, 475s
1
(SnꢀO), 285br (SnꢀCl). H NMR (DMSO-d6, 293 K):
l, 0.84 (t, 6H, SnꢀCH2CH2CH2CH3), 1.2–1.3 (m, 8H,
SnꢀBun), 1.5–1.6 (m, 4H, SnꢀBun), 6.8–7.7 (m, 8H,
Haromatic), 9.16 (s, 1H, CHsalopH ), 10.2, 10.8 (s br,
2
OHsalopH and/or NHsalopH ). 13C NMR (DMSO-d6, 293
2
K): l, 13.82 (s, SnꢀBun),217.04 (s, SnꢀBun), 25.66 (s,
SnꢀBun), 27.73 (s, SnꢀBun), 116.24, 116.63, 116.86,
117.31, 118.19, 118.89, 119.31, 119.44, 119.60, 119.71,
122.32, 124.22, 128.99, 129.34, 131.90, 133.44, 134.74,
136.40 (s, Caromatic), 150.79, 155.89, 157.28, 159.65,
160.79, 161.04, 161.70, 167.24, 191.68 (s, CO and CN).
119Sn NMR (DMSO-d6, 293 K), l −211.1. \M
(DMSO, c (mol l−1)=1.1×10−3)=0.05 V−1 cm2
mol−1. UV (CHCl3, umax, nm): 243, 270, 355.
tively high residual electron density (about 1 e A−3),
,
however, without chemical meaning was found for
,
structures 4 and 9 at the distance ꢀ1 A from the tin
atoms.
Crystallographic data and some details of data col-
lection and structures refinement are given in Table 1.
The most relevant bond distances and angles in the
structures of 4, 7 and 9 are listed in Table 2. From the
recrystallisation of compound 15 we have obtained
good-quality crystals of 1 for which a single crystal
X-ray study has been previously reported [8]. Our data
compare well with those in literature [8] and are in-
serted in Table 2.
2.5. X-ray crystallography
The data for the complexes 4, 7 and 9 were collected
on an Image-Plate diffractometer (IPDS, Stoe) using

C. Pettinari et al. / Inorganica Chimica Acta 325 (2001) 103–114
109
Table 2
Selected bond distances and angles of complexes 1, 4, 7 and 9
a
Distances/angles [SnMe2(Salop)](1)
[SnVi2(Salop)] (4)
[SnCl2(Salop)(CH3OH)]·CH3OH (7)
[SnBr2(Salop)(CH3OH)] (9)
SnꢀO(1)
SnꢀO(2)
SnꢀN
SnꢀC(14)
SnꢀC(16)
SnꢀX(1)
SnꢀX(2)
SnꢀO(3)
2.117(2)
2.139(3)
2.221(3)
2.112(3)
2.117(4)
2.117(2)
2.125(2)
2.227(2)
2.112(2)
2.113(2)
2.009(2)
2.055(2)
2.171(3)
2.005(2)
2.056(2)
2.178(5) b
2.348(1)
2.400(1)
2.182(2)
2.506(1)
2.553(1)
2.194(3)
C(14)ꢀSnꢀC(16) 140.1(1)
X(1)ꢀSnꢀX(2)
138.3(1)
96.18(4)
162.6(1)
90.0(1)
77.55(9)
83.69(9)
82.83(9)
83.76(9)
96.72(3)
161.5(1)
90.1(1)
76.6(1)
83.3(1)
82.3(1)
82.9(1)
O(1)ꢀSnꢀO(2)
O(1)ꢀSnꢀN
O(2)ꢀSnꢀN
158.7(1)
75.4(1)
83.5(1)
158.88(8)
75.79(7)
83.34(7)
O(1)ꢀSnꢀO(3)
O(2)ꢀSnꢀO(3)
NꢀSnꢀO(3)
C(14)ꢀSnꢀO(1)
C(16)ꢀSnꢀO(1)
C(14)ꢀSnꢀO(2)
C(16)ꢀSnꢀO(2)
C(14)ꢀSnꢀN
C(16)ꢀSnꢀN
X(1)ꢀSnꢀO(1)
X(1)ꢀSnꢀO(2)
X(2)ꢀSnꢀO(1)
X(2)ꢀSnꢀO(2)
X(1)ꢀSnꢀN
97.8(1)
99.3(1)
87.4(1)
89.6(1)
112.3(1)
106.9(1)
98.60(8)
95.91(8)
91.00(9)
89.12(8)
108.57(9)
112.81(8)
97.15(7)
93.43(7)
96.00(7)
96.60(7)
168.55(7)
91.91(7)
88.16(6)
175.66(6)
97.41(9)
93.72(8)
96.07(9)
97.30(9)
167.5(1)
92.3(1)
X(2)ꢀSnꢀN
X(1)ꢀSnꢀO(3)
X(2)ꢀSnꢀO(3)
88.09(7)
175.19(6)
a For [SnMe2(Salop)], C(15) in the atom list corresponds to C(16) in this table. The data for this compound derived from our determination,
more refined with respect to that reported in Ref. [8].
b The geometrical parameters are given for the main (80%) component of the disordered Salop ligand.
3. Results and discussion
With the triorganotin(IV) derivatives SnR3Cl, the
complexes [SnR3(salopH)] (R=Me or Bun) 15 and 16,
containing the monoanionic Schiff base likely coordi-
nate in bidentate fashion, have been prepared.
3.1. Synthesis
From the reaction of SnR2Cl2 acceptors with an
equimolar amount of 2-{[(2-hydroxyphenyl)imino]-
methyl}phenol(salopH2) in methanol in the presence of
bases (KOH, MeONa or NEt3), the complexes
[SnR2(Salop)] 1–5 (R=Me, Ph, Vi, Bun, But), contain-
ing the donor in the dianionic tridentate form, have
been obtained (Fig. 2). When SnRX3 or SnX4 acceptors
were employed in the same reaction conditions, the
complexes [SnX2(salop)(S)] 6–13 (X=Cl, Br, I or R;
R=Me, Ph or Bun; S=H2O or MeOH) (Fig. 3) can be
easily obtained. Although these reactions seem to be
instantaneous when all reactants are mixed, refluxing
for approximately 24 h was carried out to ensure
complete reaction.
On the other hand the reaction of SnX4 with 2 mol of
SalopH2 and 4 mol of base affords the compound
[Sn(salop)2] 14 in which all halides groups have been
substituted by two dianionic tridentate Schiff bases.
Fig. 2. Structure proposed for the diorganotin(IV) salop derivatives.

110
C. Pettinari et al. / Inorganica Chimica Acta 325 (2001) 103–114
protonation of the ligand and involvement of both
phenolate oxygens in bonding to tin. In the triorganotin
complexes 15 and 16, the presence of a broad absorp-
tion between 2600 and 2300 cm−1 indicates that only
one phenolic group is deprotonated, that is in accor-
dance with a bidentate O,N-coordination of the ligand.
In the 3500–2300 cm−1 region the spectra of 17 and 18
are similar to that of the free ligand, indicating coordi-
nation of salopH2 in neutral form. In the spectra of
di-(6–10) and mono-halo (11–13) complexes, new
broad absorptions at ca. 3400–3000 cm−1, due to
w(OꢀH) of MeOH or H2O bonded to tin, were detected
according to the formulations proposed.
In derivatives 1–16 the w(CꢁN) band, occurring be-
tween 1617 and 1567 cm−1, is considerably shifted
towards lower frequencies with respect to that of the
free Schiff base (1631–1593 cm−1), confirming the
coordination of the azomethine nitrogen to the
diorganotin(IV) moiety. The stretching frequency is
lowered owing to the displacement of electron density
from N to Sn atom, thus resulting in the weakening of
the CꢁN bond as reported in the literature [16]. The
major shift of CꢁN is observable in the IR spectrum of
the halide derivatives 6–13 as compared with that in
the triorganotin species 14 and 15, indicating a strong
participation of N atoms of the former in the coordina-
tion to the Sn atom. On the other hand, the w(CꢁN)
remains unchanged in the spectra of adducts 17 and 18
with respect to the free base, whereas a band assignable
to w(CꢀO) stretching vibration at approximately 1290
cm−1 in the ligand is shifted to 1250 cm−1 upon
adduct formation. Coordination through the phenolic
oxygen is confirmed by l(OꢀH) absorption deforma-
tion, which falls at approximately 1290 cm−1 in the
spectra of 17 and 18.
In the spectra of 1–16 we have assigned some bands
in the region 460–500 cm−1 to w(SnꢀO) which in our
series seems to be little influenced by the type of
halogen bonded to tin, but strongly influenced by the
number and type of organic groups. The 20 cm−1
increase on going from Me and Bun to Ph can be
interpreted in terms of the inductive effect of the in-
creasing electron withdrawing power of the correspond-
ing organic groups, which strengthens the SnꢀO bonds.
The absorptions at approximately 262 and 243 cm−1
(5), 577 and 533 cm−1 (2) and finally 573 and 545
cm−1 (1) are due to w(SnꢀPh), w(SnꢀBun) and
w(SnꢀMe), respectively [17]. In the case of 3 and 4
(SnꢀBut2 and SnꢀVin2 derivatives) the assignment of
w(SnꢀC) is not certain, due to the overlapping with
SnꢀO and Whiffen-notation bands. The presence of
three absorptions due to SnꢀC in the spectra of tri-
organotin(IV) derivatives 15–16 is in accordance with a
five-coordinate tbp fac-SnR3 structure, with two other
positions likely occupied by two donor atom from
Salop [18].
Fig. 3. Structure proposed for the mono- and dihalotin(IV) salop
derivatives.
Finally, if the reaction between salopH2 and SnR2Cl2
was carried out in diethyl ether or CHCl3 in the absence
of a base, the adducts [SnR2Cl2(salopH2)] 17 and 18
were formed.
Compounds 1–13 can be also prepared by refluxing a
mixture of the proligand salopH2 with the tin(IV) ac-
ceptors in toluene with azeotropical removal of water.
Under our conditions no derivative was obtained
when SnCy3Cl or SnPh3Cl were employed.
In some cases, from the reaction of salopH2 with di
and tri organotin(IV) acceptors, the mono-organ-
otin(IV) complexes were obtained due to dissociation of
the starting acceptors according to the reaction of
Kocheskov [14].
In the presence of moisture the [SnR2(salop)] and
[SnR3(salopH)] complexes slowly hydrolyse even in
CHCl3 solution, yielding the R2SnO and (R3Sn)2O ox-
ides or the hydroxides R3SnOH [15]. The hydrolysis is
faster when R=Bun. The adducts 17 and 18 are not
stable in solution yielding, in quantitative yields after
48 h, complexes 1 and 2, respectively.
Compounds 1–16 are stable under atmospheric con-
ditions and are thermally stable up to their m.p. They
all have intense colours (red, orange or yellow) and are
soluble in acetone, DMSO and chlorinate solvents in
which they are non-electrolytes, thus ruling out ionic
structure or displacement of the ligand salop by solvent
molecules, with the exception of compounds 8–10 for
which in DMSO a conductivity value has been found in
accordance with the partial ionic dissociation (Eq. (1)).
[SnX2(salop)(CH3OH)]+xDMSO
X[SnX2−n(salop)(DMSO)x]++nX−+CH3OH (1)
(n=1 or 2, X=Br or I)
3.2. Spectroscopy
3.2.1. IR
Selected IR data for all complexes are reported in
Section 2.
The strong broad band due to w(OꢀH), centred in the
free donor at approximately 2300 cm−1, disappears in
the complexes 1–14, in accordance with complete de-

C. Pettinari et al. / Inorganica Chimica Acta 325 (2001) 103–114
111
3
In the far-IR region of 6–10 two w(SnꢀO) and two or
more w(SnꢀCl), w(SnꢀBr) and w(SnꢀI) bands were de-
tected, indicating halogen atoms being in cis position in
accordance with crystal structures (see above). For
SnꢀX stretching absorptions, the following trend, typi-
cal of dihalide complexes, has been found: w(SnCl)\
w(SnBr)\w(SnI) [19].
is possible to observe the J(SnꢀH) coupling involving
the azomethine proton, thus indicating direct SnꢀN
3
bonding. The magnitude of J(SnꢀH) can be employed
to evaluate the strenght of SnꢀN interaction. It has
3
been found that the values of J(SnꢀH) in mono and
di-halotin(IV) derivatives are greater than in the tri-
organotin(IV) complexes 15 and 16. The 1H NMR
spectrum of the adducts 17 and 18 shows the azome-
thine proton unchanged with respect to the free ligand
indicating the absence of coordination of the imine N
atom to tin atom.
3.2.2. UV spectra
Details of the electronic spectra (in all cases recorded
in CHCl3) are also given in the experimental section.
The spectra of 1–14 remain unchanged after a few
days, confirming the stability of the complexes and
remain unaffected by dilution. The spectra of 1–16
contain a characteristic band in the region 240–267 nm
and two or more intense broad bands in the region
280–456 nm. The band in the region 240–270 nm can
be considered a p–p* benzenoid band, in view of the
assignments made by Chatterijee and Douglas [20]. In
the UV–Vis spectra of 1–5, all three bands, due to
conjugate systems of the coordinated ligand, reveal a
red shift with respect to analogue absorptions in the
spectrum of free salopH2. In particular, the absorption
at 354 nm, due to CꢁN system between phenyl rings in
salopH2, undergoes a shift to approximately 454–465
nm.
In the 1H NMR spectra of 1–9 and 11–13 the HCꢁN
proton is observed as one sharp singlet due to absence
of isomers or fluxionality in solution. In the H NMR
1
spectrum of the diiodo complex 10 three different sig-
nals have been found for the HCꢁN groups. This
multiplicity, also found in the 13C and 119Sn spectra, is
in accordance with the occurrence of equilibrium 1.
The J(119Snꢀ1H) of dimethyltin derivative 1 has a
2
value of 78.1 Hz, typical of five-coordinated tin species.
On the basis of Lockarts’s Eq. (2):
[Me−Sn−Me]=0.0161×
(2J(119Sn−1H))2−1.32×2J(119Snꢀ1H)+133.4 (2)
the MeꢀSnꢀMe angle is estimated to approximately
128° [22]. The discrepancy between the CꢀSnꢀC angle
from X-ray data (see below) and the empirical estima-
tion in solution suggests a change of the structure with
the long SnꢀO bond interaction being likely broken
upon dissolution.
The replacement of methyl or butyl groups by the
more electronegative chloride results in pronounced
blue shifts of the long wavelength absorption band of
the coordinated dinegative anion, a behaviour previ-
ously reported for other tin(IV) derivatives containing
schiff bases [21].
The spectra of the adducts 17 and 18 are similar to
that of the free ligand, suggesting that in chloroform
solution they completely dissociate into starting
reagents, as also indicated by NMR data (see below).
The 13C NMR spectra show a significant downfield
shift of all carbon resonances. The shift is a conse-
quence of an electron density transfer from the ligand
n
to the acceptor. The J(119Snꢀ13C) coupling constants
were detected in the case of sufficiently soluble deriva-
tives. In derivatives 1–5, the order of magnitude of the
coupling constants is the same as those previously
reported for analogous five-coordinate derivatives [23],
whereas in the case of derivatives 11–13 the
nJ(119Snꢀ13C) are close to those found for six-coordi-
nate skewed trapezoidal organotin(IV) complexes
[19,23]. By using the simple linear relationship between
1J(119Snꢀ13C) and the CꢀSnꢀC bond angles derived by
Lockart [22] and Howard [24] for dimethyltin species a
value has been found for compound 1 in the range
130–134° which well agrees with the angle of 138°
found in the crystal structure [8].
3.2.3. NMR spectra
The 1H NMR data for the ligand and its tin(IV)
complexes have been reported in Section 2. The choice
of the solvent was dictated by the solubility, the order
of preference being CDCl3, acetone-d6 and DMSO-d6.
The absence of the OH proton signals in the complexes
1–14 further supports the binding of the tin centre to
both ligand oxygen atoms through the replacement of
both phenolic hydrogens. Whereas the OH resonance is
present in the spectra of the triorganotin(IV) complexes
15 and 16, in accordance with a partial deprotonation
of the ligand, as also in the adducts 17 and 18, in which
the ligand is in the neutral form. The chemical shift
values of the ligand protons in 1–16 are as expected: a
downfield shift in the l value of azomethine (HCꢁN)
proton resonance upon coordination, supports the liga-
tion of azomethine nitrogen to tin. The SnꢀN bond
found in the solid state (see below) is retained also in
solution. In fact, in the proton NMR spectra of 1–16 it
The 119Sn NMR spectra of 1–5 show only one sharp
resonance in the range −140 to −330 ppm, typical of
five-coordinated diorganotin compounds [23]. As previ-
ously reported the 119Sn chemical shift increases with
the following order:
Me:BunBButBVinBPh

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C. Pettinari et al. / Inorganica Chimica Acta 325 (2001) 103–114
The 119Sn NMR chemical shift of 6–13 is typical of
oxygen atoms (SnꢀO: 2.117(2) and 2.125(2) A) are in
axial positions, with a OꢀSnꢀO angle of 158.88 (8)°.
The vinyl groups, directed above and below the plane
defined by Sn, N and both O atoms, adopt a conforma-
tion with the terminal C atom bent toward the O2 of
salop, the CꢀSnꢀC angle being 138.3(1)°. Each molecu-
lar units weakly interact with another one through the
O1 atom of salop, which is involved in an interaction
with the metal of the second complex molecule
,
six-coordinate tin(IV) [19,23] and increases also when
the R groups are replaced by more electronegative
groups such as halides. As previously reported in the
case of acylpyrazolonates the trend of chemical shift
can be related to the electron-withdrawing inductive
effect of the halogens and also to the possibility of
additional p-contribution to the SnX bonds which
would shield the nucleus to a greater extent. In the
119Sn spectrum of 10 four resonances have been de-
tected, two at approximately −621 ppm likely due to
[Sn(salop)(DMSO)2(CH3OH)]2+[I2]2− and two at ap-
proximately −814 ppm—due to [SnI(salop)(DMSO)-
(CH3OH)]+[I]− species in accordance with equilibrium
1 proposed on the basis of the conductivity measure-
ments which indicate the existence in solution of 1:1
electrolytes.
,
(Sn···O:2.748(2)A). The structure is very similar to that
of derivatives 1 and 5, reported previously [8,9], how-
ever, in 5 no Sn···O interactions between the complex
molecules were found, and the CꢀSnꢀC angle was less
(121.4°) than in 1 and 4.
The equatorial angles in the structure of 4 are close
to that reported for [SnMe2(salop)] [8], whereas they
differ from those reported for diphenyltin derivative [9].
The SnꢀO distances are in the range typical for the
Sn(IV) derivatives of salop, but are slightly shorter with
respect to those reported for [SnBun 2(Vanophen)] [6 h].
The monomeric [SnVin2(salop)] units are linked into
dimers by weak intermolecular interactions with SnꢀO
distance being 2.748(2). This is similar to [SnMe2-
(salop)] complex [8], in which the value of additional
1
The H and 119Sn NMR spectra of the adducts 17
and 18 are typical of completely dissociated species, all
signals being analogous to that of the free ligand and of
the solvated organotin species.
3.3. X-ray diffraction study
,
The single-crystal X-ray diffraction (XRD) study of
derivative 4 shows the tin center coordinated by five
donor atoms, two O and one N from the salop ligand
and two C of the vinyl groups, in a distorted trigonal
pyramidal geometry (Fig. 4). The distortion is mainly
due to the rigidity of chelate rings, together with the
large covalent radius of tin(IV). The nitrogen (SnꢀN:
SnꢀO bonding is 2.881(8) A, but differs from
[SnPh2(salop)] [9], in which this interaction is absent
likely due to steric factors. The comparison of three
structures with R=Me, Vin, Ph shows the [SnVin2-
(salop)] derivative being much more similar to methyl-
one. On the contrary to 4, the divinyltin(IV) derivative
of N-(2-hydroxyacetophenone)glycinate reported re-
cently contains a water molecule coordinated to tin
[25]. The coordination of water in this case can be
,
2.227(2) A) and the carbon atoms (SnꢀC: 2.112(2) and
,
2.113(2) A) occupy the equatorial plane, whereas the
Fig. 4. The molecular structure of 4.

C. Pettinari et al. / Inorganica Chimica Acta 325 (2001) 103–114
113
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for an individual grant 00-220 to Dr. A. Drozdov.

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