Synthesis and structural characterization of diorganotin(IV) esters with pyruvic acid isonicotinyl hydrazone and pyruvic acid salicylhydrazone Schiff bases

Article abstract of DOI:10.1016/j.jorganchem.2004.12.037

Eight diorganotin esters of Schiff base ligands formulated as [R ₂SnLY]₂, where L₁ is 4-NC₅H ₄CON₂C(CH₃) CO₂ with Y = H ₂O, R = Ph (1), PhCH₂ (2)

Full text of DOI:10.1016/j.jorganchem.2004.12.037

Journal of Organometallic Chemistry 690 (2005) 1669–1676
www.elsevier.com/locate/jorganchem
Synthesis and structural characterization of diorganotin(IV)
esters with pyruvic acid isonicotinyl hydrazone and pyruvic acid
salicylhydrazone Schiff bases
*
Han Dong Yin , Min Hong, Qi Bao Wang, Sheng Cai Xue, Da Qi Wang
Department of Chemistry, Liaocheng University, Liaocheng 252059, China
Received 1 December 2004; accepted 30 December 2004
Abstract
Eight diorganotin esters of Schiff base ligands formulated as [R2SnLY]2, where L1 is 4-NC5H4CON2C(CH3) CO2 with Y = H2O,
R = Ph (1), PhCH2 (2), m-ClC6H4CH2 (3), and L2 is 2-HOC6H4CON2C(CH3) CO2 with Y = CH3OH, R = PhCH2 (4), o-
ClC6H4CH2 (5), m-ClC6H4CH2 (6), o-FC6H4CH2 (7), p-FC6H4CH2 (8) have been prepared and characterized by elemental analysis,
1
IR, H and 119Sn NMR spectra. The crystal structures of compounds 1, 2 and 4 have been determined by X-ray single crystal dif-
fraction. Their structures show that the tin atoms of three compounds are all rendered seven-coordinated in distorted pentagonal
bipyramid geometries with a planar SnO4N unit and two apical aryl carbon atoms. A comparison of the IR spectra of the ligands
with those of the corresponding compounds, reveals that the disappearance of the bands assigned to carbonyl unambiguously con-
forms that the ligands coordinate with tin in the enol form.
ꢀ 2005 Elsevier B.V. All rights reserved.
Keywords: Schiff base; Hydrazone; Diorganotin; Crystal structure
1. Introduction
such as nitrogen, revealed new structural types which
may lead to compounds with different activities [5–10].
In line with these developments, we have recently re-
ported some diorganotin compounds of pyruvic acid
isonicotinyl hydrazone [11]. As a continuation of this
line of investigation, we now synthesized eight diorgano-
tin esters of Schiff base ligands pyruvic acid isonicotinyl
hydrazone and salicylhydrazone by different reaction
methods. The details of the structure and spectral char-
acterizations of the compounds 1–8 are reported herein.
Three of the compounds have been studied by X-ray dif-
fraction, and reveal that these three compounds are all
dimers and adopt the same structure. Furthermore, for
compounds 1 and 2, because of the presence of intermo-
lecular hydrogen bonds, their structures show a one-
dimensional indefinite chain arrangement. And the
Schiff base ligands, pyruvic acid isonicotinyl hydrazone
and salicylhydrazone, were both found to be introduced
The studies of diorganotin(IV) compounds are of cur-
rent interest owing to their wide range of applications as
biocides and homogeneous catalysts in the industry [1].
In recent years, there have been more and more reports
on the synthesis, antitumor activities and structural elu-
cidation of various diorganotin(IV) derivatives of car-
boxylic acid [2–5]. In particular, there has been
considerable interest in structural studies of diorgano-
tin(IV) compounds of carboxylic acid, because there
are many possible bonding interactions between the
oxygen atom of carboxyl group and tin atom. Studies
on diorganotin(IV) compounds of carboxylic acid hav-
ing carboxylate ligands with additional donor atom,
*
Corresponding author. Tel./fax: +866358238121.
E-mail address: hangdongyin@sohu.com (H.D. Yin).
0022-328X/$ - see front matter ꢀ 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2004.12.037

1670
H.D. Yin et al. / Journal of Organometallic Chemistry 690 (2005) 1669–1676
into the inner coordination sphere and can thus function
as tridentate chelates with O, N and O atoms occupying
suitable positions for the coordination.
5.23(2H, s, CH2Cl2), 5.51(6H, s, H2O), 6.72–7.17(20H,
m, Ph–H), 8.03(4H, d, J = 5.20 Hz, 3,5-pyridine–H),
8.82(4H, d, J = 5.20 Hz, 2,6-pyridine–H). 119Sn NMR
(CDCl3, ppm): ꢀ458.5. IR (KBr, cmꢀ1) m: 3415(m,
H2O), 2978, 2921(s, Ar–H), 2854(m, C–H), 1609,
1363(m, CO2), 1618(m, C@N), 1602(s, C@N–N@C),
1204(s, C–O), 678(s, Sn–O), 546(w, Sn–C), 475(m,
Sn–N).
2. Experimental
2.1. Materials and methods
Triphenyltin hydroxide, isonicotinic acid hydrazide,
salicylhydrazide and pyruvic acid were commercially
available and used without further purification. Triaryl-
tin chlorides were prepared by a standard method re-
ported in the literature [12]. All the solvents used in
the reactions were of AR grade and dried using standard
literature procedures. The melting points were obtained
with Kolfer micro melting point apparatus and were
uncorrected. IR spectra were recorded with a Nicolet-
460 spectrophotometer, as KBr discs. 1H and 119Sn
NMR spectra were recorded on a Mercury Plus-400
NMR spectrometer in CDCl3, and chemical shifts were
given relative to Me4Si and Me4Sn. Elemental analyses
were performed with a PE-2400 II elemental analyzer.
2.3.2. Preparation of {(PhCH2)2Sn[4-
NC5H4CON2C(CH3)CO2](H2O)}2 (2)
Pyruvic acid isonicotinyl hydrazone (0.5 mmol) and
tribenzyltin chloride (0.5 mmol) were added to a solu-
tion of dry toluene (30 ml) and heated under reflux with
stirring for 1 h. After the triethylamine (0.5 mmol) was
added to the reactor, the reaction mixture was refluxed
for 1 h more. The clear solution thus obtained was evap-
orated under vacuum to form a white solid and recrys-
tallized in methanol to give colorless crystals. Yield:
81%, m.p. 145 C. Anal. Calc. for C46H46N6O8Sn2: C,
52.66; H, 4.39; N, 8.01%. Found: C, 52.81; H, 4.42; N,
7.95%. 1H NMR (CDCl3, 400 MHz): d 2.21(6H, d,
J = 6.00 Hz, CH3), 3.13(8H, t, JSn–H = 88.80 Hz,
PhCH2Sn), 5.51(4H, s, H2O), 6.72–7.17(20H, m, Ph–
H), 7.81(4H, d, J = 5.20 Hz, 3,5-pyridine–H), 8.79(4H,
d, J = 4.80 Hz, 2,6-pyridine–H). 119Sn NMR (CDCl3,
ppm): ꢀ469.5. IR (KBr, cmꢀ1) m: 3022(m, Ar–H),
2921(s, C–H), 1633(s, C@N), 1604(s, C@N–N@C),
1615, 1334(s, CO2), 1203(s, C–O), 697(s, Sn–O),
544(m, Sn–C), 479(w, Sn–N).
2.2. Synthesis of Schiff base ligands
2.2.1. Preparation of pyruvic acid isonicotinyl hydrazone
The Schiff base has been prepared with isonicotinic
acid hydrazide and pyruvic acid in ethanol according
to the literature [13], and a mount of white powder
was obtained. Yield: 95%, m.p. 222–223 ꢁC. Anal. Calc.
for C9H9N3O3: C, 48.14; H, 5.00; N, 18.38%. Found: C,
48.00; H, 4.89; N, 18.67%.
2.3.3. Preparation of {(m-ClC6H4CH2)2Sn[4-
NC5H4CON2C(CH3)CO2]}2 (3)
Compound 3 was prepared using the same procedure
as described for compound 2 and recrystallized from
methanol to give yellow crystals. Yield: 82%, m.p. 138
ꢁC. Anal. Calc. for C46H38Cl4N6O6Sn2: C, 48.02; H,
3.31; N, 8.35%. Found: C, 47.81; H, 3.55; N, 8.39%.
1H NMR (CDCl3, 400 MHz): d 2.26(6H, d, J = 6.00
Hz, CH3), 3.55(8H, t, JSn–H = 84.80 Hz, PhCH2Sn),
6.52–7.11(16H, m, Ph–H), 7.76(4H, d, J = 6.40 Hz,
3,5-pyridine–H), 8.81(4H, d, J = 4.80 Hz, 2,6-pyridine–
H). 119Sn NMR (CDCl3, ppm): ꢀ459.5. IR (KBr,
cmꢀ1) m: 3058(m, Ar–H), 2933(s, C–H), 1631(s, C@N),
1598(s, C@N–N@C), 1608, 1355(s, CO2), 1192(s,
C–O), 683(m, Sn–O), 562(w, Sn–C), 487(m, Sn–N).
2.2.2. Preparation of pyruvic acid salicylhydrazone
The Schiff base has been prepared with salicylhydraz-
ide and pyruvic acid in ethanol according to the litera-
ture [14], and white acicular crystals were obtained.
Yield: 80%, m.p. 216 ꢁC. Anal. Calc. for C10H10N2O4:
C, 54.92; H, 4.54; N, 12.61%. Found: C, 54.72; H,
4.68; N, 12.85%.
2.3. Synthesis of diorganotin compounds
2.3.1. Preparation of {Ph2Sn[4-
NC5H4CON2C(CH3)CO2](H2O)}2 Æ CH2Cl2 Æ H2O (1)
Pyruvic acid isonicotinyl hydrazone (0.5 mmol) was
added to a benzene solution (30 ml) of Ph3SnOH (0.5
mmol). The mixture was heated under reflux with stir-
ring for 6 h. The clear solution thus obtained was evap-
orated under vacuum to form a yellow sticky material
and recrystallized in dichloromethane–hexane to give
light yellow crystals. Yield: 63%, m.p. 238 ꢁC. Anal.
Calc. for C43H42Cl2N6O9Sn2: C, 47.12; H, 3.84; N,
2.3.4. Preparation of {(PhCH2)2Sn[2-
HOC6H4CON2C(CH3)CO2](CH3OH)}2 (4)
Pyruvic acid salicylhydrazone (0.5 mmol) and triben-
zyltin chloride (0.5 mmol) were added to a solution of
dry toluene (30 ml) and heated under reflux with stirring
for 1 h. After the triethylamine (0.5 mmol) was added to
the reactor, the reaction mixture was refluxed for 1 h
more. The clear solution thus obtained was evaporated
under vacuum to form a white solid and recrystallized
1
5.84%. Found: C, 47.31; H, 3.78; N, 5.66%. H NMR
(CDCl3, 400 MHz): d 2.21(6H, d, J = 6.00 Hz, CH3),

H.D. Yin et al. / Journal of Organometallic Chemistry 690 (2005) 1669–1676
1671
in methanol to give colorless crystals. Yield: 78%, m.p.
135 ꢁC. Anal. Calc. for C50H52N4O10Sn2: C, 54.23; H,
4.70; N, 5.06%. Found: C, 53.81; H, 4.79; N, 5.12%.
1H NMR (CDCl3, 400 MHz): d 11.18(2H, s, Ar–OH),
8.15(2H, s, R–OH), 6.94–7.49(28H, m, Ar–H and Ph–
H), 3.35–3.49(8H, m, PhCH2Sn), 1.89(12H, s, CH3).
119Sn NMR (CDCl3, ppm): ꢀ445.5. IR (KBr, cmꢀ1):
3419(m, OH), 3024(s, Ar–H), 2936(s, C–H), 1625(s,
C@N), 1608(s, C@N–N@C), 1588, 1322(s, CO2),
1211(s, C–O), 698(s, Sn–O), 524(w, Sn–C), 489(w, Sn–
N).
The other compounds, {R2Sn[2-HOC6H4CON2C-
(CH3)CO2]}2 [R=o-ClC6H4CH2 (5), m-ClC6H4CH2 (6),
o-FC6H4CH2 (7), p-FC6H4CH2 (8)], were prepared anal-
ogously with appropriate trialkyltin chloride and their
analytical data are presented below.
N@C), 1596, 1333(s, CO2), 1209(m, C–O), 674(m, Sn–
O), 565(w, Sn–C), 475(m, Sn–N).
2.3.8. {(p-FC6H4CH2)2Sn[2-
HOC6H4CON2C(CH3)CO2]}2 (8)
Compound 8 was recrystallized from methanol to
give orange precipitate. Yield: 86%, m.p. 124 ꢁC. Anal.
Calc. for C48H40F4N4O8Sn2: C, 51.73; H, 3.59; N,
1
5.03%. Found: C, 51.74; H, 3.62; N, 4.96%. H NMR
(CDCl3, 400 MHz): d 11.28(2H, s, Ar–OH), 6.91–
7.49(24H, m, Ar–H and Ph–H), 3.45–3.57(8H, m,
PhCH2Sn), 1.79(6H, s, CH3). 119Sn NMR (CDCl3,
ppm): ꢀ455.5. IR (KBr, cmꢀ1): 3387(m, OH), 3026(s,
Ar–H), 2925(s, C–H), 1614(m, C@N), 1606(s, C@N–
N@C), 1591, 1321(s, CO2), 1201(m, C–O), 676(m, Sn–
O), 545(w, Sn–C), 468(w, Sn–N).
2.3.5. {(o-ClC6H4CH2)2Sn[2-
HOC6H4CON2C(CH3)CO2]}2 (5)
2.4. X-ray crystallography
Compound 5 was recrystallized from methanol to
give orange-red precipitate. Yield: 72%, m.p. 131 ꢁC.
Anal. Calc. for C48H40Cl4N4O8Sn2: C, 48.84; H, 3.39;
N, 4.75%. Found: C, 49.11; H, 3.56; N, 4.72%. 1H
NMR (CDCl3, 400 MHz): d 11.16(2H, s, Ar–OH),
6.83–7.64(24H, m, Ar–H and Ph–H), 3.22–3.50(8H, m,
PhCH2Sn), 1.64(6H, s, CH3). 119Sn NMR (CDCl3,
ppm): ꢀ448.5. IR (KBr, cmꢀ1): 3417(m, OH), 3021(m,
Ar–H), 2916(m, C–H), 1618(m, C@N), 1603(s, C@N–
N@C), 1586, 1321(s, CO2), 1209(m, C–O), 677(m, Sn–
O), 525(w, Sn–C), 465(w, Sn–N).
Crystallographic data and refinement details are given
in Table 1. X-ray crystallographic data for compounds 1,
2 and 4 were collected on a Bruker SMART CCD 1000
diffractometer at 298(2) K using Mo Ka radiations
˚
(0.71073 A). The structure was solved by direct method
and differential Fourier map using SHELXL-97 program,
and refined by full-matrix least-squares on F2. All non-
hydrogen atoms were refined anisotropically. Positions
of hydrogen atoms were calculated and refined isotropi-
cally. The weighting scheme employed for 1 was of the
2
form w ¼ 1=½r2ðF o2Þ þ ð0:0707PÞ þ 0:0000Pꢁ, where
2
P ¼ ðF 2o þ 2F c2Þ=3, w ¼ 1=½r2ðF 2oÞþ ð0:1143PÞ þ 1:8551Pꢁ
2.3.6. {(m-ClC6H4CH2)2Sn[2-
HOC6H4CON2C(CH3)CO2]}2 (6)
for 2, where P ¼ ðF 2o þ 2F c2Þ=3, and w ¼ 1=½r2ðF 2oÞþ
2
ð0:0743PÞ þ 1:8716Pꢁ for 4, where P ¼ ðF 2o þ 2F c2Þ=3.
Compound 6 was recrystallized from methanol to
give orange-red precipitate. Yield: 85%, m.p. 129 ꢁC.
Anal. Calc. for C48H40Cl4N4O8Sn2: C, 48.84; H, 3.39;
N, 4.75%. Found: C, 49.33; H, 3.36; N, 4.52%. 1H
NMR (CDCl3, 400 MHz): d 12.56(2H, s, Ar–OH),
6.55–7.63(24H, m, Ar–H and Ph–H), 3.22–3.41(8H, m,
PhCH2Sn), 1.74(6H, s, CH3). 119Sn NMR (CDCl3,
ppm): ꢀ465.5. IR (KBr, cmꢀ1): 3421(m, OH), 3019(m,
Ar–H), 2933(m, C–H), 1622(s, C@N), 1609(s, C@N–
N@C), 1594, 1351(s, CO2), 1211(m, C–O), 654(m, Sn–
O), 547(m, Sn–C), 459(w, Sn–N).
3. Results and discussion
3.1. Preparations
The compounds [R2SnLY]2 were produced by the
reaction from pyruvic acid isonicotinyl hydrazone with
triphenyltin hydroxide or triaryltin chloride, and pyru-
vic acid salicylhydrazone with triaryltin chloride, in the
1:1 molar ratio. It is clear that the existence of enolic
proton of ligands leads to the production of dearylation
of triaryltin carboxylates, R3Sn(C9H7N3O3) and
R3Sn(C10H8N2O4), the major products of R3SnOH or
R3SnCl with Schiff base ligands, and the seven-coordi-
nate dimeric composition formed as a result of steric ef-
fect or solvent effects in the recrystallization. Analogous
reactions could also be found in the dearylation of
(R3Sn)2O or R3SnOH with other carboxylic acids [15–
17], but they do not have the same mechanism as these.
Through crystal structure determination, it can be seen
that the structures of compounds 1–3 were one-dimen-
sional infinite chain polymers because of the presence
2.3.7. {(o-FC6H4CH2)2Sn[2-
HOC6H4CON2C(CH3)CO2]}2 (7)
Compound 7 was recrystallized from methanol to
give orange-red precipitate. Yield: 72%, m.p. 131 ꢁC.
Anal. Calc. for C48H40F4N4O8Sn2: C, 51.73; H, 3.59;
N, 5.03%. Found: C, 51.88; H, 3.52; N, 4.97%. 1H
NMR (CDCl3, 400 MHz): d 11.22(2H, s, Ar–OH),
6.81–7.55(24H, m, Ar–H and Ph–H), 3.30–3.53(8H, m,
PhCH2Sn), 1.88(6H, s, CH3). 119Sn NMR (CDCl3,
ppm): ꢀ471.5. IR (KBr, cmꢀ1): 3418(m, OH), 3019(s,
Ar–H), 2922(m, C–H), 1622(m, C@N), 1602(s, C@N–

1672
H.D. Yin et al. / Journal of Organometallic Chemistry 690 (2005) 1669–1676
Table 1
Crystallographic data of compounds 1, 2 and 4
Compound
1
2
4
Empirical formula
Formula weight
Temperature (K)
C43H42Cl2N6O9Sn2
1095.11
298(2)
C46H46N6O8Sn2
1048.27
298(2)
C50H52N4O10Sn2
1106.34
298(2)
˚
Wavelength (A)
0.71073
Orthorhombic
P212121
0.71073
Monoclinic
C2/c
0.71073
Monoclinic
P21/c
Crystal system
Space group
Unit cell dimensions
˚
a (A)
11.3674(17)
11.7201(18)
35.127(3)
90
32.866(7)
9.8428(18)
28.491(5)
95.917(4)
9168(3)
19.124(2)
18.444(2)
15.3732(19)
112.699(2)
5002.6(11)
4
˚
b (A)
˚
c (A)
b(ꢁ)
Volume (A )
3
˚
4679.8(11)
4
1.554
Z
8
1.519
4224
Calculated density (mg/m3)
F(000)
1.469
2240
2192
Crystal size (mm)
Scan range h (ꢁ)
Total/unique/Rint
Goodness-of-fit on F2
Refined parameters
Reflections with I > nr(I)
R1/wR2
0.45 · 0.28 · 0.22
2.1–25.0
24460/8142/0.065
1.004
0.51 · 0.43 · 0.22
1.8–25.0
22817/7990/0.027
1.004
0.57 · 0.48 · 0.42
1.8–25.0
25832/8804/0.031
1.014
603
587
571
6155, n = 2
0.052/0.115
1.24
5897, n = 2
0.039/0.124
1.148
5472, n = 2
0.035/0.091
1.058
l (mmꢀ1
)
q
max/qmin (e Aꢀ3
)
0.94 and ꢀ0.66
1.13 and ꢀ0.50
0.99 and ꢀ0.48
of the intermolecular hydrogen bond interactions
formed by the coordination water molecule and the pyr-
idine nitrogen atom of the adjacent unit. While the other
compounds 4–8 with pyruvic acid salicylhydrazone were
all monomers.
1633 and 1598–1609 cmꢀ1 in the spectra of these com-
pounds indicate the presence of C@N and C@N–N@C
groups [18]. The stretching frequencies of interest are
those associated with the COO, Sn–O and Sn–N groups.
The spectra of all the compounds show some common
characters. The explicit feature in the infrared spectra
of all compounds, strong absorption appearing at about
680 cmꢀ1 in the respective spectra of the compounds,
which is absent in the free ligands, is assigned to the
Sn–O stretching mode of vibration. The weak- or med-
ium-intensity band in the region 459–489 cmꢀ1 can be
assigned to Sn–N stretching vibration. All these values
are consistent with that detected in a number of organo-
tin(IV) derivatives [19,20], and the infrared spectra of
compounds 4–8 show strong typical broad bands at
3387–3421 cmꢀ1 related to the phenolic hydrogen
A possible mechanism is given in Schemes 1 and 2.
3.2. IR data
A remarkable difference between the IR spectra of the
ligands and those of the corresponding compounds is
that the stretching vibration bands of carbonyl disap-
pear from the spectra of the compounds. The disappear-
ance of the bands assigned to carbonyls unambiguously
confirms that the ligands coordinated with the tin are in
the enol form. The characteristic absorptions at 1614–
4-NC H CONH-N=C(CH )CO H+ Ph SnOH
Ph Sn[4-NC H CONH-N=C(CH )CO ]
+ H O
3 5 4 3 2
5
4
3
2
3
2
enolization
Ph Sn[4-NC H CONH-N=C(CH )CO ]
3
5
4
3
2
Ph Sn[4-NC H C(OH)=N-N=C(CH )CO ]
3 5 4 3 2
-PhH
Ph Sn[4-NC H CON C(CH )CO ]
2
5
4
2
3
2
H O
2
{Ph Sn[4-NC H CON C(CH )CO ](H O)}
2
2
5
4
2
3
2
2
Compound 1
Scheme 1.

H.D. Yin et al. / Journal of Organometallic Chemistry 690 (2005) 1669–1676
1673
Et N
3
+
-
R Sn[X-CONH-N=C(CH )CO ] + (Et N H)Cl
X-CONH-N=C(CH )CO H + R SnCl
3
3
2
3
3
2
3
enolization
R Sn[X-CONH-N=C(CH )CO ]
R Sn[X-C(OH)=N-N=C(CH )CO ]
3
3
2
3
3
2
-RH
R Sn[X-CON C(CH )CO ]
2
2
3
2
Y
{R Sn[X-CON C(CH )CO ]Y}
2
2
3
2
2
(i)
R=PhCH
2
3
X=4-NC H , Y=H O
2
6
5
4
2
R=m-ClC H CH
4
2
(ii) X=2-HOC H , Y=CH OH R=PhCH
2
4
5
6
7
8
6
4
3
R=o-ClC H CH
6
4
2
R=m-ClC H CH
6
4
2
R=o-FC H CH
6
4
2
2
R=p-FC H CH
6
4
Scheme 2.
stretching vibration according to the previous report
[21], which strongly indicates that in these compounds
the phenolic oxygen atoms do not participate in coordi-
nation to the atoms.
tin atom (and possibly the type of donor atoms of the
ligand), it may be used with a cation to infer the coordi-
nation number of the tin atom [23]. The 119Sn NMR
data show only one signal around –455 ppm for com-
pounds 1–8, typical of a seven-coordinate species, and
have been found in accordance with the crystalline state
structure [24]. This further confirms the dimeric struc-
tures for all compounds.
In organotin carboxylates, the IR spectra can provide
useful information concerning the coordinate form of
the carboxyl. The IR spectra of compounds 1–8 show
that the mas and ms bands are assigned to the regions
1588–1615 and 1321–1363 cmꢀ1, respectively. The mag-
nitude of Dm[mas(COO) ꢀ ms(COO)] occurring at 243–281
cmꢀ1 indicates that the carboxylate ligands function as
monodentate ligand under the conditions employed
[9], respectively. These conclusions are supported by
the results of X-ray diffraction studies.
3.5. X-ray crystallography
3.5.1. Structures of {Ph2Sn[4-NC5H4–
(O)N2C(CH3)CO2](H2O)}2 Æ CH2Cl2 Æ H2O (1)
and {(PhCH2)2Sn[4-NC5H4–
C(O)N2C(CH3)CO2](H2O)}2 (2)
1
3.3. H NMR spectra
The crystal structures of compounds 1 and 2 have
been determined. The structures conform to the same
motif. The [R2SnL(H2O)]2 units are connected in poly-
meric structures as shown in Figs. 1–4, respectively, se-
1
In H NMR spectra of the two free ligands, a single
resonance for the proton in –NHN@ group is observed
at 1487 and 1495 ppm, which are absent in the spectra of
the compounds, indicating the deprotonation of the
–NHN@ group, and confirming that the ligands coordi-
nate with the tin in the enol form. For compounds 1–3,
the spectra show that the chemical shifts of the protons
on the pyridine ring exhibited two sets of signals in d
7.79–8.82 as a doublet and in d 7.76–8.03 as a doublet,
too, and the coupling constant is equal to 4.80–5.20
Hz. The Ar–OH resonance appeared in the region
11.16–12.56 ppm as singlet for the compounds 4–8
strongly suggests that the phenolic oxygen atoms do
not participate in coordination to the tin atoms, and this
is quite different from that of the four compounds we
have reported [22].
˚
lected bond lengths (A) and angles (ꢁ) are listed in
3.4. 119Sn NMR spectra
Although d(119Sn) is influenced by several factors,
including the aromatic of the R group bound to the
Fig. 1. Molecular structure of compound 1.

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H.D. Yin et al. / Journal of Organometallic Chemistry 690 (2005) 1669–1676
Fig. 4. Packing of the molecules in a unit cell of compound 2
for 2. The aryl groups occupy the apical position, the ax-
ial–Sn–axial, C19–Sn1–C25 is 172.7(3)ꢁ and C31–Sn2–
C37 is 174.2(3)ꢁ for 1, C10–Sn1–C17 is 168.5(2)ꢁ and
C33–Sn2–C40 is 167.5(2)ꢁ for 2. The structures are very
similar to that of derivatives reported previously [11].
The bond distances of Sn1–O7 and Sn2–O8 are
Fig. 2. Packing of the molecules in a unit cell of compound 1.
˚
2.288(6) and 2.274(6) A, respectively, for 1, Sn1–O4
˚
and Sn2–O8 are 2.291(5) and 2.327(4) A for 2, which
are relatively longer than those in the analogous
[5,9,18,25], due to the formation of intradimeric hydro-
˚
˚
gen bonds, O7ꢂ ꢂ ꢂO5 (2.619 A) and O8ꢂ ꢂ ꢂO2 (2.643 A)
˚
˚
for 1, O4ꢂ ꢂ ꢂO6 (2.583 A) and O8ꢂ ꢂ ꢂO2 (2.652 A) for 2,
and interdimeric hydrogen bonds, O7ꢂ ꢂ ꢂN3#1 [ꢀx + 1,
˚
y + 1/2, ꢀz + 3/2] (2.808 A) and O8ꢂ ꢂ ꢂN6#2 [x ꢀ 1/2,
˚
ꢀy + 3/2, ꢀz + 2] (2.785 A) for 1, O4ꢂ ꢂ ꢂN6#1 [x,
˚
ꢀy + 2, z + 1/2] (2.651 A) and O8ꢂ ꢂ ꢂN3#2 [x, ꢀy + 1,
˚
z ꢀ 1/2] (2.804 A) for 2. Neighboring molecules are held
together by hydrogen bonds O7ꢂ ꢂ ꢂN3#1 and
O8ꢂ ꢂ ꢂN6#2 for 1, O4ꢂ ꢂ ꢂN6#1 and O8ꢂ ꢂ ꢂN3#2 for 2.
These hydrogen bonds contribute to the crystal stability
and compactness and result in a one-dimensional linear
chain arrangement from the intermolecular bonds (Figs.
2 and 4). Furthermore, for compound 1, the crystal con-
sists of discrete dimeric compound and solvent (H2O
and CH2Cl2) molecules in the ratio of 1:1:1. The solvent
molecules do not have any obvious interaction with the
dimer.
Fig. 3. Molecular structure of compound 2.
Tables 2 and 3. Intermolecular hydrogen bonds [2.808,
˚
˚
2.785 A for 1 and 2.651, 2.804 A for 2] create a contin-
uous one-dimensional polymeric chain.
For compounds 1 and 2, all Sn atoms are chelated by
the tridentate ligands, and molecular structures reveal
dinuclear dimers with a central Sn2O2 four-membered
ring. Every tin atom exists in a distorted pentagonal
bipyramidal coordination environment in which one
water molecule, one tridentate pyruvic acid isonicotinyl
hydrazone ligand, and two trans aryl groups coordinate
to Sn center. Tin and the bonded oxygen and nitrogen
atoms are nearly coplanar and deviate only slightly from
regular pentagonal geometry, mean deviations from
3.5.2. Structure of {(PhCH2)2Sn[2-HOC6H4–
C(O)N2C(CH3)CO2](CH3OH)}2 (4)
The crystal structure and unit cell of compound 4 are
shown in Figs. 5 and 6, respectively. All hydrogen
atoms have been omitted for the purpose of clarity.
Tables 2 lists the selected bond lengths and angles for
compound 4.
˚
˚
plane are 0.0041, 0.0111 A for 1 and 0.0220, 0.0358 A

H.D. Yin et al. / Journal of Organometallic Chemistry 690 (2005) 1669–1676
1675
Table 2
˚
Selected bond distances (A) and angles (ꢁ) for compounds 1, 2 and 4
1
Sn1–O3
2.177(6)
2.288(7)
2.288(6)
2.385(6)
2.538(5)
Sn2–O6
Sn2–O8
2.191(6)
2.274(6)
2.282(7)
2.360(6)
2.552(5)
Sn1–N1
Sn1–O7
Sn2-N4
Sn2–O4
Sn2–O1
Sn1–O1
Sn1–O4
C19-Sn1–C25
C19-Sn1–O3
C19-Sn1–N1
C19-Sn1–O7
C19-Sn1–O4
172.7(3)
C31–Sn2–C37
C31–Sn2–O6
C31–Sn2–O8
C31–Sn2-N4
C31–Sn2–O1
174.2(3)
92.3(3)
93.5(3)
88.4(3)
87.1(2)
91.9(3)
88.7(3)
92.0(3)
87.6(2)
2
Sn1–O3
2.165(4)
2.260(4)
2.291(5)
2.383(3)
2.597(3)
168.5(2)
93.8(2)
Sn2–O7
Sn2-N4
2.168(3)
2.272(4)
2.327(4)
2.414(3)
2.637(3)
167.5(2)
98.00(17)
93.4(2)
Sn1–N1
Sn1–O4
Sn2–O8
Sn2–O5
Sn2–O1
Sn1–O1
Sn1–O5
C17–Sn1–C10
C17–Sn1–O3
C17–Sn1–N1
C17–Sn1–O4
C17–Sn1–O1
C40–Sn2–C33
C40–Sn2–O7
C40–Sn2-N4
C40–Sn2–O8
C40–Sn2–O5
95.5(2)
88.8(3)
89.2(2)
88.2(2)
87.29(19)
Fig. 5. Molecular structure of compound 4.
4
Sn1–O3
2.158(3)
2.227(4)
2.296(3)
164.5(2)
94.03(17)
99.81(17)
Sn1–O5
Sn1–O1#1
2.403(4)
2.816(3)
Sn1–N1
Sn1–O1
C11–Sn1–C18
C11–Sn1–O3
C11–Sn1–N1
C11–Sn1–O5
C11–Sn1–O1#1
C11–Sn1–O1
82.88(18)
85.92(15)
91.02(16)
Symmetry transformations used to generate equivalent atoms: #1: ꢀx,
ꢀy + 1, ꢀz + 1.
Table 3
˚
Hydrogen-bonding geometry (A, ꢁ)
D-Hꢂ ꢂ ꢂA
Compound 1
D-H
Hꢂ ꢂ ꢂA
Dꢂ ꢂ ꢂA
D-Hꢂ ꢂ ꢂA
O7-H43ꢂ ꢂ ꢂO5
O7-H44ꢂ ꢂ ꢂN3#1
O8-H45ꢂ ꢂ ꢂO2
O8-H46ꢂ ꢂ ꢂN6#2
0.845
0.848
0.849
0.847
1.846
2.02
1.81
2.619
2.808
2.643
2.785
151.58
154.17
166.5
1.998
154.36
Fig. 6. Packing of the molecules in a unit cell of compound 4.
Compound 2
O4-H1ꢂ ꢂ ꢂN6#1
O4-H2ꢂ ꢂ ꢂO6
0.897
0.899
0.898
0.896
2.142
1.706
1.951
1.783
2.651
2.583
2.804
2.652
115.19
164.21
158.19
162.83
bipyramidal coordination environment in which one
methanol molecule, one tridentate pyruvic acid salicyl-
hydrazone ligand, and two trans benzyl groups coordi-
nate to each Sn center. The atoms O1, O1#1, O5, O3
O8-H3ꢂ ꢂ ꢂN3#2
O8-H4ꢂ ꢂ ꢂO2
Compound 4
˚
and N1 are coplanar within 0.0485 A, which form the
O5-H51ꢂ ꢂ ꢂO2#1
0.898
1.764
2.639
164.31
equatorial plane. Furthermore, the angle of the axial
C18–Sn1–C11 is 164.5(2)ꢁ, which deviates from the lin-
ear angle of 180ꢁ. The O1 atom of the carboxylate resi-
due also binds the other tin atom, Sn1#1, generating a
Sn2O2 four-membered ring. The distance of Sn1–O1#1
Symmetry transformations used to generate equivalent atoms: com-
pound 1: #1 ꢀx + 1, y + 1/2, ꢀz + 3/2; #2 x ꢀ 1/2, ꢀy + 3/2, ꢀz + 2.
compound 2: #1 x, ꢀy + 2, z + 1/2; #2 x, ꢀy + 1, z ꢀ 1/2. compound 3:
#1 ꢀx, ꢀy + 1, ꢀz + 1.
˚
For compound 4, the asymmetric unit contains two
monomers, which are different from a crystallographic
point of view. The conformations of the two indepen-
dent molecules are almost the same, with only small dif-
ferences in bond lengths and bond angles. In this
compound, the Sn atom exists in a distorted pentagonal
[ꢀx, ꢀy + 1, ꢀz + 1] (2.816(3) A) is relatively longer
˚
than that of Sn1–O1 (2.296(3) A), but is comparable
with those found in related seven-coordinate diorgano-
tin systems [5,9]. Thereby, the molecular structure of this
compound can be described as a dimer, and the coordi-
nation geometry of tin can also be described as a

1676
H.D. Yin et al. / Journal of Organometallic Chemistry 690 (2005) 1669–1676
[3] Z.Q. Yang, X.Q. Song, Q.L. Xie, Chin. J. Org. Chem. 16 (1996)
111.
trans-C2SnO4N pentagonal bipyramid with the two ben-
zyl groups occupying trans positions. Furthermore, in
the dimeric structure there also exist intramolecular
hydrogen bonds between another carboxyl oxygen atom
O2 without coordinating to Sn atom and hydroxyl
hydrogen atoms of the coordinated methanol molecule,
[4] W.G. Lu, J.X. Tao, X.Y. Li, Y.Z. Wang, Chin. J. Appl. Chem. 17
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[5] H.D. Yin, C.H. Wang, Y. Wang, C.L. Ma, J.X. Shao, Chem. J.
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[6] F.L. Lee, E.J. Gabe, L.E. Khoo, W.H. Leong, G. Eng, F.E.
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˚
O2ꢂ ꢂ ꢂO5#1 (2.639 A). Undoubtedly, these hydrogen
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bonds contribute to the compactness of the dimer.
Meanwhile, studies show that the phenolate oxygen
atoms are also in nonparticipation in coordination to
the tin atom.
[8] L.E. Khoo, Y. Xu, N.K. Goh, L.S. Chia, L.L. Koh, Polyhedron
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4259.
[10] S.W. Ng, J. Organomet. Chem. 585 (1999) 12.
[11] H.D. Yin, M. Hong, Q.B. Wang, Indian J. Chem. 43A (2004)
2301.
4. Supplementary material
Crystallographic data for the structural analysis have
been deposited with the Cambridge Crystallographic
Data Center, CCDC No. 257091 for compound 1,
CCDC No. 257092 for compound 2 and CCDC No.
257093 for compound 4. Copies of this information
may be obtained from The Director, CCDC, 12 Union
Road, Cambridge CB2 1EZ, UK (fax: +44 1223
336033; e-mail: deposit@ccdc.cam.ac.uk or www:
http://www.ccdc.cam.ac.uk).
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Acknowledgements
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We acknowledge the Financial support of the Shan-
dong Province Science Foundation, and the State Key
Laboratory of Crystal Materials, Shandong University,
PR China.
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