New diorganotin(IV) complexes of salicylaldehyde based hydrazones bearing furan heterocycle moiety: X-ray structural investigation of dimethyltin(IV) and diphenyltin(IV) complexes

Article abstract of DOI:10.1016/j.jorganchem.2017.12.037

Some new diorganotin(IV) derivatives formulated as R₂SnL (where R = Me, Bu, Ph and Oct) were obtained upon treatment of diorganotin(IV) precursors with acylhydrazones [H₂L^a = N’-(2-hydroxy-3-methoxybenzylidene)furan-2-carb

Full text of DOI:10.1016/j.jorganchem.2017.12.037

Accepted Manuscript
New diorganotin(IV) complexes of salicylaldehyde based hydrazones bearing furan
heterocycle moiety: X-ray structural investigation of dimethyltin(IV) and diphenyltin(IV)
complexes
Sundeep Kumar, Mala Nath
PII:
S0022-328X(17)30735-0
10.1016/j.jorganchem.2017.12.037
JOM 20232
DOI:
Reference:
To appear in: Journal of Organometallic Chemistry
Received Date: 17 October 2017
Revised Date: 19 December 2017
Accepted Date: 30 December 2017
Please cite this article as: S. Kumar, M. Nath, New diorganotin(IV) complexes of salicylaldehyde
based hydrazones bearing furan heterocycle moiety: X-ray structural investigation of dimethyltin(IV)
and diphenyltin(IV) complexes, Journal of Organometallic Chemistry (2018), doi: 10.1016/
j.jorganchem.2017.12.037.
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ACCEPTED MANUSCRIPT

ACCEPTED MANUSCRIPT
New diorganotin(IV) complexes of salicylaldehyde based hydrazones bearing
X-ray structural investigation of dimethyltin(IV) and
furan heterocycle moiety:
diphenyltin(IV) complexes
Sundeep Kumara and Mala Natha*
a Department of Chemistry, Indian Institute of Technology Roorkee, Roorkee-247667, Uttarakhand, India.
* Corresponding author. Tel. : +91 1332 285797; Fax: +91 1332 73560.
E-mail address: malanfcy@iitr.ernet.in (M. Nath)
Abstract
Some new diorganotin(IV) derivatives formulated as R2SnL (where R = Me, Bu, Ph and
diorganotin(IV) precursors
acylhydrazones [H La = N'-
Oct) were obtained upon treatment of
(2-hydroxy-3-methoxybenzylidene)furan-2-carbohydrazide, H2Lb
benzylidene)furan-2-carbohydrazide and H2Lc
N'-(2-hydroxy-5-nitrobenzylidene)furan-2-
carbohydrazide] derived from Schiff base condensation of furan-2-carbohydrazide and substituted
with
2
=
N'-(5-chloro-2-hydroxy-
=
salicylaldehydes in methanol in appropriate molar ratio
. The enolic tridentate chelating mode of the
2+
acylhydrazones
towards the diorganotin moieties [R2Sn(IV)] was ascertained by micro-analysis
and various spectroscopic techniques viz., Fourier-transform infrared (FT-IR), multinuclear (1H,
13C and 119Sn) magnetic resonance (NMR) and electrospray ionization mass (ESMS) spectrometry.
The single crystal X-ray diffraction investigation of Me2SnLb and Ph2SnLb demonstrates that they
crystallize in monoclinic space groups ‘P 21’ and ‘P 21/c’ respectively, and comprised of
crystallographically discrete 2 and 4 molecules in their respective unit cells. Both mononuclear
complexes adopt a highly distorted square-pyramidal geometry (SP) wherein the imine nitrogen
preferably occupies the apical site whereas the more electronegative enolic and phenolic oxygen
atoms of the ligand and two carbon atoms of the methyl/phenyl groups of the organotin(IV) moiety
align themselves equatorially around the five-coordinated tin center in a square plane.
Diorganotin(IV) derivatives were also analyzed in air by thermo-gravimetric (TG, DTG and DTA)
techniques to elucidate their thermal stability and decomposition trends.
1. Introduction
In metal coordination chemistry, hydrazones have been widely recognized as versatile
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ligands because they are endowed with remarkable chelating behaviour and structural flexibility in
many metal complexes. In the last few years, numerous acylhydrazones were documented and
evaluated as potential drug candidates to prevent the menace of the life threatening diseases such as
malaria, cancer and β-thalas semia major (Fe-overload disease) etc. [1-3]. Recently, many
organotin(IV) complexes of acylhydrazones were evaluated to exhibit promising antibacterial and
antitumor activities against the standard drugs [4,5]. Further, the interactions of organotin(IV)
derivatives of the acylhydrazones with DNA/BSA were investigated by various spectroscopic
techniques to explore their mode of actions as metal-based anticancer drugs [6]. The mode of
biochemical action of the organotin(IV) complexes were reported to be governed by a variation in
their structures, coordination state, nature of the ligating donor atoms and number/nature of the
alkyl/aryl groups bound to the tin atom [7,8]. Meanwhile, several organotin(IV) derivatives of
acylhydrazones were also investigated to exhibit structural diversity viz., distorted trigonal-
bipyramidal (TBP) or square-pyramidal (SP) geometry around a penta-coordinated tin atom
consisting of the imine N atom invariably at the equatorial and axial sites respectively, and a
pentagonal-bipyramidal geometry for a seven-coordinated tin atom located in a C2O4N core along
with two alkyl/aryl groups aligned trans to each other wherein organotin(IV) complexes acted as a
Lewis acid to accommodate the electron density either from molecules of employed solvents or
donor atoms of other molecules resulting in a weakly-bridged dimers with weak Sn…O bonding
interactions [9-11]. Furthermore, fascinating 1D chains, 2D sheets and 2D/3D networks
supramolecular structures were occasionally observed as a consequence of self-assembly of the
organometallic subunits through intramolecular O-H...X or C-H…X (X = O, N or F) hydrogen
bonding interactions, which were reported to be unaffected by the variation of the aryl groups of
the Schiff base ligands [12,13]. Moreover, many ligating possibilities of acylhyrazones of ortho-
hydroxyaldehydes containing a third potential coordination site were reported on the basis of
availability of the varying sets of donor sites viz., monobasic ON bidentate, monobasic ONO
tridentate or a dibasic ONO tridentate chelation [14,15]. The inadequate work reported on the
structural chemistry of the diorganotin(IV) complexes of the furancarboxylic acid hydrazones
[10,16], and interesting keto-enol tautomerization imparting structural flexibility to them in
literature profoundly prompted us to design new diorganotin(IV) derivatives of salicylaldehyde
based hydrazones bearing furan heterocycle moiety. Herein, we have highlighted the synthesis and
characterization of eleven new diorganotin(IV) derivatives formulated as R2SnLa-c (where R = Me,
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Bu, Ph and Oct) of documented acylhydrazones derived from furan-2-carbohydrazide and
in the presence of trimethylamine base (a mild proton abstractor)
. The
substituted salicylaldehyde
coordination mode of the ligands towards the various organotin(IV) moieties was ascertained by
investigating the dimethyl- and diphenyl organotin(IV) complexes, Me2SnLb and Ph2SnLb with
single crystal X-ray diffraction crystallographic analysis.
Insert Fig. 1
2. Experimental
2.1. Materials
Organotin precursors viz., dimethyltin(IV) dichloride, diphenyltin(IV) dichloride, di-n-
butyltin(IV) dichloride and di-n-octyltin(IV) oxide were procured from Sigma Aldrich and
Merck-Schuchardt respectively. Furoic acid hydrazide (Sigma Aldrich), o-vanillin (Sigma
Aldrich), 5-chlorosalicylaldehyde (Sigma Aldrich), 5-nitrosalicylaldehyde (Hi-Media), and
triethylamine (AR grade, Rankem) etc. were utilized as received commercially. Methanol (LR
grade, Rankem) was employed as a solvent without its further purification throughout the
synthesis.
2.2. Physical measurements
All solid compounds, compactly packed in one-end sealed glass capillaries were used to
observe their melting points on an OptiMelt Automated Melting Point System, Stanford Research
Systems instrument equipped with a Digital Image Processing Technology, and melting points so
obtained were invariably uncorrected. Solid samples of all synthesized compounds were carefully
loaded on a VarioMicro CHNS Elemental analyzer instrument (Ser. No.: 15136064) in order to
perform the micro-analysis for the percentage of C, H and N contents. Dried and uniformly
pressed potassium bromide pellets, provided by dispersing fine powder of solid compounds in a
spectroquality KBr (matrix) were employed to obtain their IR spectra in the frequency range of
4000 to 400 cm–1 on a Nicolet 6700 Nexus FT-IR Spectrophotometer. Acquisition of all multi-
nuclear (1H, 13C, and 119Sn) magnetic resonance spectral data of studied compounds were acquired
NMR
CDCl
solvents viz. deutero chloroform (
dimethyl sulfoxide
3) and deutero
in deuterated
((CD3)2SO) on a Bruker Avance (Bruker Bio Spin GmbH, 500.133 MHz) FT NMR spectrometer
and
FT-NMR spectrophotometer at ambient
a JEOL Delta (JNM-ECX400II, 400 MHz)
1
13
temperature.
All H and C NMR spectra were referred to the residual solvent signals, assigned
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invariably at δ = 7.26 and 2.5 for proton, and 77.16 and 39.52 ppm for carbon resonances when
CDCl3
(CD3)2SO
[17], respectively. Electro-spray ionization (ES-MS) mass
acquired in
and
spectral analysis was preferably executed in a positive ion detection mode, and ES-MS mass
spectra were collected from the SAIF, Central Drug Research Institute, Lucknow, India. Single
Me2SnLb and Ph2SnLb were collected on a
crystal X-ray diffraction data for the compounds
Bruker Kappa Apex-II charge-coupled device (CCD) detector diffractometer
equipped with a
graphite monochromated Mo Kα radiation (λ = 0.71073 Å) source at ambient temperature at the
Institute Instrumentation Centre (IIC), Indian Institute of Technology Roorkee (IITR), Roorkee,
India. Acquisition of diffraction data was acquired by mounting suitable yellow crystals of
Me2SnLb and Ph2SnLb,
dimensions 0.40 × 0.37 × 0.35 mm and 0.35 × 0.33 × 0.37 mm for
respectively.
The diffraction data was processed using Direct method with SIR-92 programme in
order to obtain the solutions for the crystal structures [18]. Anisotropic refinement of all non-
hydrogen atoms was achieved by “full matrix least-squares calculations based on F2” using
SHELXL97 programme [19]. The hydrogen atoms were located and positioned geometrically,
and were constrained to ride on their respective parent atoms. Illustrative ORTEP and molecular
packing diagrams were generated using Mercury, version 3.9 software. Thermograms of
diorganotin(IV) derivatives were attained on a Perkin-Elmer (Pyris Diamond) thermal analyzer by
their controlled pyrolysis (heating rate, 20 ºC/min) in a platinum crucible using alumina powder as
a reference material in the temperature range 20 to 1000 ºC with inflow air rate of 200 ml/min, at
I. I. C., IITR.
2.3. Synthesis
Acylhydrazones, N'-(2-hydroxy-3-methoxybenzylidene)furan-2-carbohydrazide (H2La), N'-
(5-chloro-2-hydroxybenzylidene)furan-2-carbohydrazide (H2Lb) and N'-(2-hydroxry-5-nitro-
benzylidene)furan-2-carbohydrazide (H2Lc), derived from the facile Schiff base condensation of
furan-2-carbohydrazide and substituted salicylaldehydes,
and their respective diorganotin(IV)
derivatives were obtained as described in the following sections:
2.3.1. Synthesis of N'-(2-hydroxy-3-methoxybenzylidene)furan-2-carbohydrazide (H2La)
To a stirred solution of furoic acid hydrazide (0.63 g, 5 mmol) in 15 mL of methanol was
dropwise added o-vanillin (0.7608
dissolved in
methanol
15 mL . After stirring for 30
g, 5 mmol)
min on a magnetic stirrer, the bright yellow solution was refluxed for ca. 5 h on a water bath
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under dry nitrogen atmosphere. The refluxed yellow solution was then allowed to attain ambient
temperature, and subsequently refrigerated overnight, which gradually yielded a white crystalline
solid by rigorous manual stirring for a while. The white crystalline ligand so precipitated was
then carefully filtered under reduced pressure, washed with 20 mL of cold methanol, and dried in
vacuo for further use.
White solid; Yield: 81%; m.p. 152-153 ºC; Anal. Calcd. for C13H12N2O4 (M. Wt. 260.25): C,
60.00; H, 4.65; N, 10.76. Found: C, 59.79; H, 5.01; N, 10.31;
ES-MS (m/z): 301.0
Selected
[(C13H12N2O4)+K]+; 283.0 [(C13H12N2O4)+Na]+; 261.61/261.0862 [(C13H12N2O4)+H]+;
-1
FT-IR Data (KBr, ν
/cm ): 3344, ν(O-H); 3202, ν(N-H); 1660, ν(C=O); 1610, ν(C=N)
;
max
azomethine
1H NMR (500.13 MHz, (CD ) SO, δ(ppm)):
3.82 (s, 3H, OCH3); 6.71 (dd, 1H, H-2, JH-H = 3.5, 1.7
3 2
Hz ); 6.86 (t, 1H, H-9, JH-H = 7.9 Hz); 7.03 (d, 1H, H-10, JH-H = 7.4 Hz); 7.14 (d, 1H, H-8, JH-H
=
7.6 Hz); 7.32 (d, 1H, H-3, JH-H = 2.5 Hz); 7.96 (s, 1H, H-1); 8.66 (s, 1H, HC=N); 10.81 (s, 1H, HN-
13C NMR (100.53 MHz, (CD ) SO, δ(ppm)):
N); 12.08 (s, 1H, HOC);
55.87, C-13; 112.25, C-2;
3 2
113.82, C-10; 115.30, C-3; 119.07, C-9; 119.13, C-7; 120.62, C-8; 146.13, C-1; 146.33, C-6;
147.09, C-4; 148.00, C-11; 148.05, C-12; 154.02, C-5.
2.3.2. Synthesis of N'-(5-chloro-2-hydroxybenzylidene) furan-2-carbohydrazide (H2Lb)
It was synthesized by following the similar synthetic route as described in section 2.3.1
using furoic acid hydrazide (0.63 g, 5 mmol) and 5-chloro-2-hydroxybenzaldehyde (0.7828
mmol).
g, 5
White solid; Yield: 78%; m.p. 200-201 ºC; Anal. Calcd. for
(M. Wt. 264.67): C,
C12H9ClN2O3
54.46; H, 3.43; N, 10.58. Found: C, 54.20; H, 3.91; N, 10.21;
ES-MS (m/z): 286.9
+
+
Selected FT-IR
[(C12H9ClN2O3)+Na] ; 264.9/265.0368 [(C12H9ClN2O3)+H] ; 123.8 [(C5H4N2O2)];
-1
1
Data (KBr, ν
/cm ): 3220, ν(O-H); 3135, ν(N-H); 1654, ν(C=O); 1625, ν(C=N)azomethine; H
max
NMR (500.13 MHz, (CD ) SO, δ(ppm)):
6.71 (s, 1H, H-2); 6.94 (d, 1H, H-11, JH-H = 8.8 Hz); 7.31
3 2
(dd, 1H, H-3, JH-H = 8.8, 2.5 Hz); 7.32 (brs, 1H, H-10); 7.64 (d, 1H, H-8, JH-H = 2.6 Hz); 7.96 (d,
13C NMR
1H, H-1, JH-H = 1.0 Hz ); 8.62 (s, 1H, HC=N); 11.14 (s, 1H, HN-N); 12.18 (s, 1H, HOC);
(100.53 MHz, (CD3)2SO, δ(ppm)):
112.72, C-2; 115.91, C-3; 118.73, C-7; C-11; 121.34, C-9;
123.54, C-8; 127.84, C-10; 131.34, C-1; 146.15, C-6; 146.70, C-4; 154.65, C-12; 156.44, C-5.
2.3.3. Synthesis of N'-(2-hydroxy-5-nitrobenzylidene) furan-2-carbohydrazide (H2Lc)
To a stirred solution of furoic acid hydrazide (0.63 g, 5 mmol) in 15 mL of methanol was
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dropwise added 2-hydroxy-5-nitrobenzaldehyde (0.7608
dissolved in
15 mL
g, 5 mmol)
methanol
. After subsequent stirring for 20 min, the yellow solid immediately precipitated out.
The reaction contents were stirred for 1 h additionally to ensure the completion of reaction. The
yellow ligand so precipitated was then carefully filtered under reduced pressure, washed with 20
mL of methanol, and dried in vacuo for further use.
Yellow solid; Yield: 83%; m.p. 272-274 ºC; Anal. Calcd. for
(M. Wt. 275.22): C,
C12H9N3O5
52.37; H, 3.30; N, 15.27. Found: C, 52.70; H, 3.34; N, 15.50;
ES-MS (m/z): 298.0
-1
+
+
Selected FT-IR Data (KBr, ν
/cm ):
max
[(C12H9N3O5)+Na] ; 276.0/276.0618 [(C12H9N3O5)+H] ;
1
3455, ν(O-H); 3276, ν(N-H); 1672, ν(C=O); 1636, ν(C=N)azomethine; H NMR (500.13 MHz,
(CD ) SO, δ(ppm)):
6.71 (s, 1H, H-2); 6.94 (d, 1H, H-11, JH-H = 8.8 Hz); 7.31 (dd, 1H, H-3, JH-H
=
3 2
8.8, 2.5 Hz); 7.32 (brs, 1H, H-10); 7.64 (d, 1H, H-8, JH-H = 2.6 Hz); 7.96 (d, 1H, H-1, JH-H = 1.0 Hz
13C NMR (100.53 MHz,
); 8.62 (s, 1H, HC=N); 11.14 (s, 1H, HN-N); 12.18 (s, 1H, HOC);
(CD3)2SO, δ(ppm)):
112.72, C-2; 115.91, C-3; 118.73, C-7, C-11; 121.34, C-9; 123.54, C-8;
127.84, C-10; 131.34, C-1; 146.15, C-6; 146.70, C-4; 154.65, C-12; 156.44, C-5.
2.3.4. Synthesis of (N-(2-hydroxy-3-methoxybenzylidene)furan-2-carbohydrazonato)dimethyl-
tin(IV)(Me2SnLa)
To a methanol (10 mL) solution of H2La (0.1301 g, 0.5 mmol) was dropwise added Et3N
(0.
1113 g, 1 mmol) in methanol (10 mL) with continuous stirring on a magnetic stirrer. A
methanol (10 mL) solution of Me2SnCl2 (0.11 g, 0.5 mmol) was then gradually added to the
stirred solution with the help of a dropping funnel. The resulting mixture was refluxed for 4 h
under N2 atmosphere on a water bath.
The intense yellow colored solution so obtained was
concentrated under reduced pressure till a yellow solid yielded which was subsequently filtered
under vacuum. The yellow solid so obtained was recrystallized from methanol/petroleum ether
(b.p. 40-60 0C) mixture (1:2 v/v), and dried in vacuo.
a
M.
Me2SnL : Yellow solid; Yield, 78%; m.p. 185-187 ºC; Anal. Calcd. for C15H16N2O4Sn (
Wt.
407.01): C, 44.27; H, 3.96; N, 6.88. Found: C, 44.68; H, 3.93; N, 7.08; ES-MS (m/z): 408.9
+
+
+
Selected FT-
[(C13H10N2O4)(Me2Sn)+H] ; 282.9 [(C13H12N2O4)+Na] ; 260.9 [(C13H12N2O4)+H] ;
-1
IR Data (KBr, ν
/cm ): 1619, ν(C=N)azomethine; 647, νas(Sn-C); 583, νs(Sn-C); 532, ν(Sn-O);
max
1
2
119
1
453, ν(Sn-N); H NMR (500.13 MHz, (CD ) SO, δ(ppm)):
0.69 (s, 6H, H-α, J( Sn- H) = 90.5
3 2
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Hz, ∟C-Sn-C =145.8°); 3.72 (s, 3H, OCH3); 5.58-6.63 (m, 2H, H-2, H-9); 6.95 (d, 2H, H-3, H-10,
JH-H = 7.9 Hz); 6.98 (d, 1H, H-8, JH-H = 3.3 Hz); 7.79 (brs, 1H, H-1); 8.74 (s, 1H, HC=N, 3J(119Sn-
13C NMR (100.53 MHz, (CD ) SO, δ(ppm)):
1H) = 35 Hz);
6.57, C-α; 55.41, C-13; 111.84, C-3;
3 2
113.26, C-2; 115.46, C-9; 115.60, C-10; 116.95, C-7; 125.83, C-8; 145.09, C-1; 148.04, C-4;
150.94, C-12; 154.11, C-11; 160.06, C-6; 161.48, C-5; 119Sn NMR (149.08 MHz, CDCl3, δ(ppm)):
-150.44.
2.3.5. Synthesis of (N-(2-hydroxy-3-methoxybenzylidene)furan-2-carbohydrazonato)dibutyltin(IV)
(Bu2SnLa
)
It was synthesized by employing the similar synthetic route as described in section 2.3.4
using H La (0.1301 g, 0.5 mmol), Et N (0.
and Bu SnCl (0.1519 g, 0.5 mmol).
2 2
1113 g, 1 mmol)
2
3
Bu SnLa: Yellow solid; Yield, 71%
Anal. Calcd. for C H N O Sn (M.
21 28 2 4
; m.p. 101-102 ºC;
2
Wt. 491.17): C, 51.35; H, 5.75; N, 5.70. Found: C, 51.67; H, 5.94; N, 6.00;
ES-MS (m/z): 515.0
[(C13H10N2O4)(Bu2Sn)+Na]+; 492.9 [(C13H10N2O4)(Bu2Sn)+H]+; 282.9 [(C13H12N2O4)+Na]+; 261.0
+
Selected FT-IR Data (KBr, νmax/cm-1): 1616, ν(C=N)azomethine; 553, ν(Sn-O);
[(C13H12N2O4)+H] ;
1
3
518, ν(Sn-C); 441, ν(Sn-N); H NMR (500.13 MHz, CDCl , δ(ppm)):
0.83 (t, 6H, H-δ, JH-H
=
3
7.3 Hz); 1.28-1.37 (m, 4H, H-β); 1.50-1.66 (m, 8H, H-α, H-γ); 3.85 (s, 3H, OCH3); 6.51 (s, 1H, H-
2); 6.66 (t, 1H, H-9, JH-H = 7.8 Hz); 6.78 (d, 1H, H-10, JH-H = 8.0 Hz); 6.92 (d, 1H, H-3, JH-H = 7.5
13C NMR
3
Hz); 7.04 (d, 1H, H-8); 7.55 (s, 1H, H-1); 8.75 (s, 1H, HC=N, J(119Sn-1H) = 41 Hz);
(100.53 MHz, CDCl3, δ(ppm)):
13.68, C-δ; 23.19, C-α; 26.55, C-γ; 26.89, C-β; 55.38, C-13;
111.77, C-3; 113.95, C-2; 115.89, C-9; 116.34, C-10; 116.61, C-7; 126.00, C-8; 144.83, C-1;
147.85, C-4; 151.34, C-12; 157.54, C-11; 161.83, C-6; 162.72, C-5; 119Sn NMR (149.08 MHz,
CDCl3, δ(ppm)): -187.53.
Synthesis of (N-(2-hydroxy-3-methoxybenzylidene)furan-2-carbohydrazonato)diphenyl-
2.3.6.
tin(IV) (Ph2SnLa)
To a methanol (10 mL) solution of H2La (0.1301 g, 0.5 mmol) was dropwise added Et3N
in methanol ( under N2
(0.
1113 g, 1 mmol)
10 mL) with continuous stirring
methanol (10 mL) solution of Ph2SnCl2 (0.1719 g, 0.5 mmol) was then gradually added to the
stirred solution with the help of a dropping funnel at ambient temperature.
atmosphere. A
After subsequent
stirring for 20 min, the yellow solid immediately precipitated out. The reaction contents were
stirred for 3 h additionally to ensure the completion of reaction. The yellow compound was
7

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carefully filtered under reduced pressure. The yellow solid so obtained was recrystallized from
methanol/petroleum ether (b.p. 40-60 0C) mixture (1:2 v/v), and dried in vacuo.
Ph2SnLa: Yellow solid; Yield, 79%; m.p. 194-195 ºC; Anal. Calcd. for C25H20N2O4Sn (M.
Wt. 531.15): C, 56.53; H, 3.80; N, 5.27. Found: C, 56.51; H, 3.70; N, 5.31;
ES-MS (m/z): 554.8
[(C13H10N2O4)(Ph2Sn)+Na]+; 532.7 [(C13H10N2O4)(Ph2Sn)+H]+; 282.9 [(C13H12N2O4)+Na]+; 260.9
Selected FT-IR Data (KBr, ν
/cm-1): 1612, ν(C=N)azomethine; 595, ν(Sn-O);
[(C13H12N2O4)+H]+;
499, ν(Sn-C); 449, ν(Sn-N); 1H NMR (500.13 MHz, CDCl , δ(ppm)):
max
3.98 (s, 3H, OCH3); 6.57
3
(dd, 1H, H-2, JH-H = 8.0, 1.5 Hz); 6.72 (t, 1H, H-8, JH-H = 7.9 Hz); 6.81 (dd, 1H, H-9, JH-H = 8.0, 1.5
Hz); 7.03 (dd, 1H, H-3, JH-H = 7.8, 1.5 Hz); 7.25 (dd, 1H, H-10, JH-H = 3.4, 0.8 Hz ); 7.59 (s, 1H, H-
1); 7.40-7.43 (m, 6H, H-β, H-γ); 7.89 (dd, 4H, H-α 3JH-H = 8.2, 3.9 Hz, 3J(119Sn-1H) = 86.0 Hz);
13C NMR (100.53 MHz, CDCl , δ(ppm)):
3
8.77 (s, 1H, HC=N, J(119Sn-1H) = 50.1 Hz);
56.87, C-
3
13; 111.99, C-3; 114.91, C-2; 116.74, C-9; 116.96, C-10; 117.23, C-7; 126.23, C-8; 129.16, C-β;
130.84, C-γ; 136.49, C-α, 2J(119Sn-13C) = 55.3 Hz; 140.01, C-ipso; 145.26, C-1, C-4, C-12; 152.04
C-11; 162.16, C-6; 162.51, C-5; 119Sn NMR (149.08 MHz, CDCl3, δ(ppm)): -329.52.
2.3.7. Synthesis of (N-(2-hydroxy-3-methoxybenzylidene)furan-2-carbohydrazonato)dioctyltin(IV)
(Oct2SnLa)
A mixture of Oct2SnO (0.1806 g, 0.5 mmol) and H2La (0.1301 g, 0.5 mmol) in methanol
(10
mL)/benzene (30 mL) mixture was refluxed for 8 h on a water bath under dry atmosphere,
and water generated during the course of the reaction was azeotropically trapped with the help of
Dean-Stark water separator. The refluxed intense yellow colored solution was filtered to remove
the unreacted reactants, and concentrated under reduced pressure till a yellow solid yielded
which was subsequently filtered under vacuum. The yellow solid so obtained was recrystallized
from methanol/petroleum ether (b.p. 40-60 0C) mixture (1:2 v/v), and dried in vacuo.
Oct2SnLa: Yellow solid; Yield, 81%; m.p. 64-65 ºC; Anal. Calcd. for C29H44N2O4Sn (M.
Wt. 603.39): C, 57.73; H, 7.35; N, 4.64. Found: C, 58.03; H, 7.55; N, 4.63;
ES-MS (m/z): 605.0
Selected FT-
[(C13H10N2O4)(Oct2Sn)+H]+; 282.9 [(C13H12N2O4)+Na]+; 260.9 [(C13H12N2O4)+H]+;
1
IR Data (KBr, ν
/cm-1): 1580, ν(C=N)azomethine; 535, ν(Sn-O); 456, ν(Sn-N); H NMR (399.78
max
3
MHz, CDCl , δ(ppm)):
0.82 (t, 6H, H-δ', JH-H = 7.0 Hz), 1.16-1.28 (m, 20H, H-γ-γ'), 1.46-1.52 (m,
3
8H, H-α, H-β), 3.84 (s, 3H, OCH3); 6.49-6.51 (m, 1H, H-2); 6.65 (t, 1H, H-9, JH-H = 7.8 Hz); 6.77
(d, 1H, H-10, JH-H = 8.1 Hz); 6.91 (d, 1H, H-3, JH-H = 7.8 Hz); 7.03 (d, 1H, H-8, JH-H = 3.4 Hz );
8

ACCEPTED MANUSCRIPT
13C NMR (100.53 MHz, CDCl3,
3
7.54 (s, 1H, H-1); 8.73 (s, 1H, HC=N, J(119Sn-1H) = 51.5 Hz);
δ(ppm)):
14.21, C-δ'; 22.74, C-γ'; 23.52, C-α; 24.76, C-β; 29.14, C-α'; 29.23, C-δ; 31.92, C-β';
33.44, C-γ; 56.34, C-13; 111.79, C-3; 113.94, C-2; 115.88, C-9; 116.35, C-10; 116.65, C-7; 125.99,
C-8; 144.80, C-1; 147.92, C-4; 157.38, C-12; 157.57, C-11; 161.80, C-6; 162.73, C-5; 119Sn NMR
(149.08 MHz, CDCl3, δ(ppm)): -187.74.
2.3.8. Synthesis of (N-(5-chloro-2-oxybenzylidene)furan-2-carbohydrazonato)dimethyltin(IV)
(Me2SnLb)
To a methanol (10 mL) solution of H2Lb (0.1323 g, 0.5 mmol) was dropwise added Et3N
(0.
1113 g, 1 mmol) in methanol (10 mL) with continuous stirring under N2 atmosphere. A
methanol (10 mL) solution of Me2SnCl2 (0.11 g, 0.5 mmol) was then gradually added to the
stirred solution with the help of a dropping funnel.
After stirring for 20 min, the yellow solid
immediately precipitated out. The reaction contents were stirred for 3 h additionally to ensure the
completion of reaction. The yellow compound was carefully filtered under reduced pressure. The
0
yellow solid so obtained was recrystallized from methanol/petroleum ether (b.p. 40-60 C)
mixture (1:2 v/v), and dried in vacuo.
Me SnLb
: Greenish yellow solid; Yield, 78%; m.p. 244-246 ºC; Anal. Calcd. for
2
M. Wt.
C14H13ClN2O3Sn (
411.43): C, 40.87; H, 3.18; N, 6.81. Found: C, 41.49; H, 3.08; N, 6.95;
ES-MS (m/z): 412.8/412.9700 [(C12H9ClN2O3)(Me2Sn)+H]+; 286.9 [(C12H9ClN2O3)+Na]+; 264.9
+
Selected FT-IR Data (KBr, νmax/cm-1):1583 ν(C=N)azomethine; 624, ν (Sn-C);
[(C12H9ClN2O3)+H] ;
as
532, ν (Sn-C); 494, ν(Sn-O); 435, ν(Sn-N); 1H NMR (500.13 MHz, (CD ) SO, δ(ppm)):
0.69 (s,
s
3 2
6H, H-α, 2J(119Sn-1H) = 90.0 Hz, ∟C-Sn-C =145.0°); 6.61 (dd, 1H, H-2, JH-H = 3.4, 1.7 Hz); 6.67
(d, 1H, H-11, JH-H = 8.9 Hz); 7.01 (d, 1H, H-3, JH-H = 3.4 Hz); 7.26 (dd, 1H, H-10, JH-H = 8.9, 2.8
3
Hz); 7.46 (d, 1H, H-8, JH-H = 2.8 Hz); 7.81 (brs, 1H, H-1); 8.74 (s, 1H, HC=N, J(119Sn-1H) = 45
13C NMR (100.53 MHz, (CD ) SO, δ(ppm)):
Hz);
6.55, C-α; 111.91, C-3; 113.60, C-2; 118.52, C-
3 2
11; 119.18, C-7; 122.98, C-9; 132.66, C-8; 133.72, C-10; 145.31, C-1; 147.85, C-4; 158.47, C-6;
161.82, C-5; 164.33, C-12; 119Sn NMR (149.08 MHz, CDCl3, δ(ppm)): -149.26.
Synthesis
(Bu2SnLb)
of
(N-(5-chloro-2-oxybenzylidene)furan-2-carbohydrazonato)dibutyltin(IV)
2.3.9.
It was synthesized by employing the similar synthetic route as described in section 2.3.4
using H Lb (0.1323 g, 0.5 mmol), Et N (0.
and Bu SnCl (0.1519 g, 0.5 mmol).
2 2
1113 g, 1 mmol)
2
3
9

ACCEPTED MANUSCRIPT
Bu2SnLb:
Anal. Calcd. for
Greenish yellow solid; Yield, 75%; m.p. 94-96 ºC;
C20H25ClN3O3Sn (M. Wt. 495.59): C, 48.47; H, 5.08; N, 5.65. Found: C, 48.53; H, 5.26; N, 5.83;
+
Selected FT-IR Data (KBr, νmax/cm-1): 1580,
ES-MS (m/z): 497.07 [(C12H9ClN2O3)(Bu2Sn)+H] ;
1
ν(C=N)azomethine; 559, ν(Sn-O); 509, ν(Sn-C); 450, ν(Sn-N); H NMR (500.13 MHz, (CD3)2SO,
3
δ(ppm)):
0.75 (t, 6H, H-δ, JH-H = 7.3 Hz); 1.19-1.27 (m, 4H, H-β); 1.36-1.52 (m, 8H, H-α, H-γ);
6.61 (dd, 1H, H-2, JH-H = 3.4, 1.7 Hz); 6.66 (d, 1H, H-11, JH-H = 8.9 Hz); 7.00 (d, 1H, H-3, JH-H
=
3.3 Hz); 7.25 (dd, 1H, H-10, JH-H = 8.9, 2.8 Hz); 7.45 (d, 1H, H-8, JH-H = 2.8 Hz); 7.81 (brs, 1H, H-
13C NMR (100.53 MHz, CDCl , δ(ppm)):
3
1); 8.77 (s, 1H, HC=N, J(119Sn-1H) = 47.0 Hz);
13.70,
3
C-δ; 22.72, C-α; 26.58, C-γ; 26.87, C-β; 111.88, C-3; 114.39, C-2; 117.46, C-11; 121.29, C-7;
122.31, C-9; 132.44, C-8; 135.11, C-10; 145.06, C-1; 147.66, C-4; 160.25, C-6; 163.02, C-5;
165.56, C-12; 119Sn NMR (149.08 MHz, CDCl3, δ(ppm)): -187.36.
Synthesis of (N-(5-chloro-2-oxybenzylidene)furan-2-carbohydrazonato)diphenyltin(IV)
(Ph2SnLb)
2.3.10.
It was synthesized by employing the similar synthetic route as described in section 2.3.6
using H Lb (0.1323 g, 0.5 mmol), Et N (0.
and Ph SnCl (0.1719 g, 0.5 mmol).
1113 g, 1 mmol)
2
2
2
3
Ph2SnLb: Greenish yellow solid; Yield, 82%; m.p. 208-210 ºC; Anal. Calcd. for
C24H17ClN2O3Sn (M. Wt. 535.57): C, 53.82; H, 3.20; N, 5.23. Found: C, 54.06; H, 3.09; N, 5.32;
ES-MS (m/z): 536.7/536.1647 [(C12H9ClN2O3)(Ph2Sn)+H]+; 288.9 [(C12H9ClN2O3)+Na]+; 264.9
+
Selected FT-IR Data (KBr, ν
max
/cm-1): 1593 ν(C=N)azomethine; 556, ν(Sn-O);
[(C12H9ClN2O3)+H] ;
1
448, ν(Sn-N); H NMR (500.13 MHz,
δ(ppm)):
CDCl3,
6.58 (dd, 1H, H-2, JH-H = 3.4, 1.7 Hz);
7.04 (d, 1H, H-11, JH-H = 9.0 Hz); 7.13 (d, 1H, H-3, JH-H = 2.7 Hz); 7.27 (s, 1H, H-10); 7.34 (dd,
1H, H-10, JH-H = 8.9, 2.7 Hz); 7.42-7.44 (m, 6H, H-β, H-γ); 7.61 (brs, 1H, H-1); 7.83 (dd, 4H, H-α,
13C NMR
3
JH-H = 6.3, 3.0 Hz, 3J(119Sn-1H) = 86.0 Hz); 8.69 (s, 1H, HC=N, 3J(119Sn-1H) = 49.5 Hz);
(100.53 MHz, CDCl , δ(ppm)):
111.94, C-3; 115.25, C-2; 117.57, C-11; 122.06, C-7; 123.75, C-9,
3
129.13, C-β; 130.93, C-γ; 132.69, C-8, 135.42, C-10; 136.26, C-α, 2J(119Sn-13C) = 57.2 Hz; 138.48,
C-ipso; 145.42, C-1; 147.46, C-4; 160.52, C-6; 162.75, C-5, 165.64, C-12; 119Sn NMR (149.08
MHz, CDCl3, δ(ppm)): -331.32.
2.3.11. Synthesis
(Me2SnLc)
of
(N-(5-nitro-2-oxybenzylidene)furan-2-carbohydrazonato)dimethyltin(IV)
It was synthesized by employing the similar synthetic route as described in section 2.3.4
10

ACCEPTED MANUSCRIPT
using H Lc (0.1376 g, 0.5 mmol), Et N (0.
1113 g, 1 mmol)
and Me SnCl (0.11 g, 0.5 mmol)
.
2 2
2
3
c
M.
Me2SnL : Yellow solid; Yield, 81%; m.p. 318 ºC (dec.); Anal. Calcd. for C14H13N3O5Sn (
Wt.
421.98): C, 39.85; H, 3.11; N, 9.96. Found: C, 40.24; H, 3.00; N, 10.08; ES-MS (m/z): 423.0
+
+
Selected FT-IR Data (KBr, νmax/cm-1):1614
[(C12H9N3O5) (Me2Sn)+H] ; 275.9 [(C12H9N3O5)+H] ;
1
ν(C=N)azomethine; 618, νas(Sn-C); 518, νs(Sn-C); 494, ν(Sn-O); 450, ν(Sn-N); H NMR (500.13
2
119
1
MHz, (CD ) SO, δ(ppm)):
0.75 (s, 6H, H-α, J( Sn- H) = 96.0 Hz, ∟C-Sn-C = 155.0°); 6.63 (dd,
3 2
1H, H-2, JH-H = 3.4, 1.7 Hz); 6.69 (d, 1H, H-3, JH-H = 9.3 Hz); 7.03 (d, 1H, H-11, JH-H = 3.4 Hz);
7.83 (s, 1H, H-1); 8.07 (dd, 1H, H-10, JH-H = 9.3, 3.0 Hz); 8.85 (d, 1H, H-8, JH-H = 3.0 Hz); 8.86 (s,
13C NMR (100.53 MHz, (CD3)2SO, δ(ppm)):
3
1H, HC=N, J(119Sn-1H) = 35.5 Hz);
8.90, C-α;
112.04, C-3; 113.93, C-2; 117.19, C-11; 121.97, C-7; 128.80, C-8; 131.65, C-10; 136.22, C-9;
145.54, C-1; 147.75, C-4; 158.19, C-6; 161.94, C-5; 171.61, C-12; 119Sn NMR (149.08 MHz,
CDCl3, δ(ppm)): -147.78.
Synthesis of (N-(5-nitro-2-oxybenzylidene)furan-2-carbohydrazonato)dibutyltin(IV)
(Bu2SnLc)
2.3.12.
It was synthesized by employing the similar synthetic route as described in section 2.3.4
using H Lc (0.1376 g, 0.5 mmol), Et N (0.
and Bu SnCl (0.1519 g, 0.5 mmol).
2 2
1113 g, 1 mmol)
2
3
Bu2SnLc:
Anal. Calcd. for C20H25N3O5Sn (M. Wt.
Yellow solid; Yield, 75%; m.p. 120-122 ºC;
506.15): C, 47.46; H, 4.98; N, 8.30. Found: C, 47.22; H, 4.85; N, 8.51;
ES-MS (m/z):
+
+
Selected FT-IR Data (KBr,
507.8/508.0884 [(C12H9N3O5) (Bu2Sn)+H] ; 297.8 [(C12H9N3O5)+Na] ;
1
νmax/cm-1): 1613, ν(C=N)azomethine; 588, ν(Sn-O); 521, ν(Sn-C); 488, ν(Sn-N); H NMR (500.13
3
MHz, (CD ) SO, δ(ppm)):
0.73 (t, 6H, H-δ, JH-H = 7.3 Hz); 1.17-1.24 (m, 4H, H-β); 1.38-1.47 (m,
3 2
8H, H-α, H-γ); 6.63 (dd, 1H, H-2, JH-H = 3.4, 1.7 Hz); 6.69 (d, 1H, H-11, JH-H = 9.3 Hz); 7.03 (d,
1H, H-3, JH-H = 3.4 Hz); 7.84 (s, 1H, H-1); 8.07 (dd, 1H, H-10, JH-H = 9.3, 3.0 Hz); 8.45 (d, 1H, H-
13C NMR (100.53 MHz, (CD ) SO, δ(ppm)):
8, JH-H = 3.0 Hz); 8.95 (s, 1H, HC=N);
13.54, C-δ;
3 2
25.55, C-α; 26.69, C-γ; 27.78, C-β; 111.98, C-3; 113.79, C-2; 116.96, C-11; 121.73, C-7; 128.91,
C-8; 131.77, C-10; 136.09, C-9; 145.47, C-1; 147.67, C-4; 158.78, C-6; 162.35, C-5; 172.37, C-12;
119Sn NMR (149.08 MHz, CDCl3, δ(ppm)): -186.04.
2.3.13. Synthesis
(Ph2SnLc)
of
(N-(5-nitro-2-oxybenzylidene)furan-2-carbohydrazonato)dipheyltin(IV)
It was synthesized by employing the similar synthetic route as described in section 2.3.6
11

ACCEPTED MANUSCRIPT
using H Lc (0.1376 g, 0.5 mmol), Et N (0.
1113 g, 1 mmol)
and Ph SnCl (0.1719 g, 0.5 mmol).
2 2
2
3
Ph2SnLc: Yellow solid; Yield, 82%; m.p. 296 ºC (dec.); Anal. Calcd. for C24H17N3O5Sn (
546.13): C, 52.78; H, 3.14; N, 7.69. Found: C, 52.69; H, 3.16; N, 7.74;
M
. Wt.
ES-MS (m/z):
/cm-1): 1613
548.00/548.0270 [(C12H9N3O5)(Ph2Sn)+H]+;
ν(C=N)
max
Selected FT-IR Data (KBr, ν
1
; 574, ν(Sn-O); 479, ν(Sn-N); H NMR (500.13 MHz, CDCl , δ(ppm)):
azomethine
6.60
3
(dd, 1H, H-2, JH-H = 3.4, 1.8 Hz); 7.12 (d, 1H, H-3, JH-H = 9.3 Hz); 7.31 (dd, 1H, H-11, JH-H = 3.4,
0.6 Hz); 7.44-7.45 (m, 6H, H-β, H-γ); 7.64 (s, 1H, H-1); 7.81-7.83 (dd, 4H, H-α, 3JH-H = 6.0, 3.5
Hz, 3J(119Sn-1H) = 90.0 Hz); 8.19 (d, 1H, H-10, JH-H = 2.8 Hz); 8.27 (dd, 1H, H-8, JH-H = 9.3, 2.9
13C NMR (100.53 MHz, (CD3)2SO + CDCl3,
3
Hz); 8.81 (s, 1H, HC=N, J(119Sn-1H) = 48.5 Hz);
δ(ppm)):
111.94, C-3; 115.62, C-2; 115.92, C-11; 122.68, C-7; 129.06, C-β, C-8; 129.72, C-10;
130.92, C-γ; 135.79, C-α; 137.80; C-9; 138.33, C-ipso; 145.52, C-1; 146.77, C-4; 159.68, C-6;
162.89, C-5; 171.62, C-12; 119Sn NMR (149.08 MHz, CDCl3, δ(ppm)): -330.94.
2.3.14. Synthesis
(Oct2SnLc)
of
(N-(5-nitro-2-oxybenzylidene)furan-2-carbohydrazonato)dioctyltin(IV)
It was synthesized by employing the similar synthetic route as described in section 2.3.7
using H2Lc (0.1376 g, 0.5 mmol) and Oct2SnO (0.1806 g, 0.5 mmol).
Oct2SnLc: Yellow solid; Yield, 77%; m.p. 93-95 ºC; Anal. Calcd. for C28H41N3O5Sn (M. Wt.
618.4): C, 54.39; H, 6.68; N, 6.80. Found: C, 54.09; H, 6.61; N, 6.93;
620.0/620.2145
[(C12H9N3O5) (Oct2Sn)+H]+; 275.8 [(C12H9N3O5)+H]+;
max
Selected FT-IR Data (KBr, ν
/cm-1):
1613 ν(C=N)azomethine; 491, ν(Sn-O); 424, ν(Sn-N); 1H NMR (399.78 MHz, CDCl , δ(ppm)):
0.82
3
3
(t, 6H, H-δ', JH-H = 7.0 Hz), 1.18-1.30 (m, 20H, H-γ-γ'), 1.57-1.66 (m, 8H, H-α, H-β), 6.53 (dd,
1H, H-2, JH-H = 3.7, 2.1 Hz); 6.75 (d, 1H, H-3, JH-H = 8.9 Hz); 7.08 (d, 1H, H-11, JH-H = 3.4 Hz);
3
7.57 (s, 1H, H-1); 8.14 (s, 1H, H-10); 8.16 (s, 1H, H-8); 8.77 (s, 1H, HC=N, J(119Sn-1H) = 39.2
13C NMR (100.53 MHz, CDCl , δ(ppm)):
Hz);
14.19, C-δ'; 22.72, C-γ'; 23.52, C-α; 24.65, C-β;
3
29.08, C-α'; 29.22, C-δ; 31.87, C-β'; 33.44, C-γ; 111.98, C-3; 114.98, C-2; 115.88, C-11; 122.45,
C-7; 129.81, C-8; 131.01, C-10; 138.06, C-9; 145.31, C-1; 147.21, C-4; 159.85, C-6; 163.43, C-5;
171.99, C-12; 119Sn NMR (149.08 MHz, CDCl3, δ(ppm)): -186.48.
Insert Scheme 1
3. Results and discussion
3.1. Synthesis, reactivity and solid-state characteristics
12

ACCEPTED MANUSCRIPT
Diorganotin(IV) derivatives of acylhydrazone Schiff base ligands viz., N'-(2-hydroxy-3-
methoxybenzylidene) furan-2-carbohydrazide (H2La), N'-(5-chloro-2-hydroxybenzylidene) furan-
2-carbohydrazide (H2Lb) and N'-(2-hydroxry-5-nitrobenzylidene)furan-2-carbohydrazide (H2Lc),
Me Bu and Ph)
were afforded after refluxing R2SnCl2 (R =
with ligands in methanol under N2
,
atmosphere, and in the presence of an efficient proton abstractor, triethylamine which facilitates
dioctyltin(IV) derivatives were
the deprotonation of ligand in 0.5 : 0.5 : 1 molar ratio. However,
obtained on refluxing Oct SnO
with ligands in 0.5 : 0.5 molar ratio in methanol/benzene mixture
2
(1:3 v/v), and by ensuring the simultaneous azeotropic removal of water from the reaction
(IV)
mixture as it is formed as described in the Experimental section (Scheme 2). All diorganotin
derivatives
are yellow solids, air-stable, and exhibit solubility in common organic solvents such
as methanol, ethanol, chloroform and dimethylsulfoxide. The analytical data, incorporated in
Experimental section clearly implies a 1:1 metal-to-ligand molar ratio in the synthesized
In all of the organotin(IV) derivatives,
diorganotin(IV) derivatives.
coordination of the ligand to
organotin(IV) moiety may be visualized through its imine nitrogen, enolic oxygen and phenolic
oxygen atoms after feasible enolisation and deprotonation during the reaction, leading to a highly
distorted square-pyramidal geometry (as illustrated in Fig. 2 and 4) at tin atom which is
ascertained by X-ray structural investigation of Me2SnLb and Ph2SnLb as described below.
Insert Scheme 2
3.2. Single crystal X-ray structural characterization
Shinning yellow needle-like and block-like crystals of adequate size and quality were
conveniently produced after slow evaporation of solvent from the respective concentrated
solutions of Me2SnLb and Ph2SnLb in methanol in perforated sealed sample vials, set aside
undisturbed over a period of few weeks at ambient temperature [20]. The single crystal X-ray
diffraction investigation of both complexes, Me2SnLb and Ph2SnLb clearly demonstrate that they
crystallized in monoclinic space groups ‘P 21’ and ‘P 21/c’, respectively, and comprise of
crystallographically discrete molecules. Table 1 organizes the relevant crystallographic data and
the structure refinement parameters of both complexes. The selected bond lengths and bond angles
are systematically arranged as captions of ORTEP diagram for molecular structure (Fig. 2 and Fig.
4) of complexes drawn at 30% ellipsoidal probability, along with the adopted non-hydrogen atoms
labeling scheme. Fig. 2 and Fig. 4 implicitly illustrate the molecular packing, elaborately viewed
13

ACCEPTED MANUSCRIPT
along the crystallographic axis ‘b’. Undoubtedly, it is fully comprehended from the crystal
N'-(5-chloro-2-hydroxybenzylidene)furan-2-
structures of both complexes that ligand,
carbohydrazide, H2Lb might have preferably undergone enolisation and deprotonation prior its
coordination to the organotin(IV) moiety in the presence of a proton abstractor in solution. As a
result,
acylhydrazone
dibasic tridentate
its imine nitrogen, enolic oxygen and phenolic oxygen atoms
form (as illustrated in Fig. 2 and Fig. 4). The adopted coordination mode of
coordinates to Me2Sn(IV) moiety or Ph2Sn(IV) moiety via
predominantly
in an enol tautomeric
acylhydrazone
ligand
led to five- and six-membered chelate rings which deviate from planarity as shown by the
measured torsions viz., Sn(1)-O(2)-C(12)-C(7) 4(2), Sn(1)-N(1)-N(2)-C(1) -2.1(8), Sn(1)-N(1)-
C(6)-C(7) 8(1), Sn(1)-O(1)-C(1)-N(2) -2(1) and Sn(01)-O(1)-C(1)-C(6) 17.5(3), Sn(01)-N(1)-
N(2)-C(8) -8.2(2), Sn(01)-N(1)-C(7)-C(6) 1.2(3), Sn(01)-O(2)-C(8)-N(2) 7.7(3) for Me2SnLb and
Ph2SnLb, respectively. The degree of distortion from an ideal geometry could conveniently be
quantified in terms of the τ values (τ = β-α/60), estimated by considering two largest consecutive
bond angles (β and α) around a penta-coordinated tin atom in the molecular structure [21]. The
estimated 0 and 1 value for τ refer to an ideal square-pyramidal geometry and ideal trigonal-
bipyramidal geometry, respectively. The respective τ values, estimated for Me2SnLb and Ph2SnLb
were found to be 0.22 (τ = 154.2-141.0/60) and 0.33 (τ = 157.93-137.85/60), respectively, which
strongly indicates a highly distorted square-pyramidal (SP) geometry in case of both complexes
wherein the apical site was invariably occupied by the N(1) whereas the equatorial sites in the
square plane were occupied by the oxygen atoms and the carbon atoms of the methyl/phenyl
groups. [21]. The highly distorted square-pyramidal (SP) geometry observed in case of Me2SnLb
and Ph2SnLb are on account of the peculiar bond angles which deviate from the ideal values viz.,
C(13)-Sn(1)-C(14) 141.0(4), C(13)-Sn(1)-O(1) 95.7(5), C(13)-Sn(1)-N(1) 101.3(4), O(1)-Sn(1)-
N(1) 72.32(16), O(2)-Sn(1)-O(1) 154.2(2), C(14)-Sn(1)-N(1) 117.4(5) and C(19)-Sn(01)-C(13)
137.85(8), O(1)-Sn(01)-O(2) 157.93(6), O(1)-Sn(01)-N(1) 84.26(6), C(19)-Sn(01)-N(1)
108.07(7), C(13)-Sn(01)-N(1) 113.82(7), O(2)-Sn(01)-N(1) 73.67(6), measured in the respective
complexes. In the present instances, the rigidity of five- and six-membered chelate rings and the
large covalent radius of the Sn(IV) atom may be thought to cause the significant deviations from
ideal geometrical parameters which otherwise may constitute a perfect square-pyramidal (SP)
geometry [22,23]. Additionally, there are significant covalent bonding interactions among O(1),
O(2), and N(1) and Me2Sn(IV) moiety or Ph2Sn(IV) moiety as evident from the values of
14

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respective bond lengths viz., Sn(1)-O(1) 2.163(4) Å, Sn(1)-O(2) 2.104(5) Å, Sn(1)-N(1) 2.203(5)
Å, and Sn(01)-O(1) 2.0753(15), Sn(01)-O(2) 2.1427(14), Sn(01)-N(1) 2.1631(17) Å, measured in
both complexes which exhibit a close resemblance to the sum of the covalent radii of Sn-O (2.10
Å) and Sn-N (2.15 Å) [24-26].
Insert Table 1
Insert Fig. 2
Symmetry operations:
(i) x, y, z; (ii) -x, y+1/2, -z.
Selected bond lengths (Å), bond angles (°) and torsion angles (°): Sn(1)-C(13) 2.096(11), Sn(1)-C(14) 2.100(11),
Sn(1)-O(1) 2.163(4), Sn(1)-N(1) 2.203(5), Sn(1)-O(2) 2.104(5), O(1)-C(1) 1.296(7), C(12)-O(2) 1.306(8), N(1)-C(6)
1.293(9), N(2)-N(1) 1.397(7), N(2)-C(1) 1.311(8), C(7)-C(6) 1.454(10), C(1)-C(2) 1.450(8), C(13)-Sn(1)-C(14)
141.0(4), C(13)-Sn(1)-O(1) 95.7(5), C(14)-Sn(1)-O(1) 92.5(5), C(13)-Sn(1)-N(1) 101.3(4), O(1)-Sn(1)-N(1) 72.32(16),
C(13)-Sn(1)-O(2) 96.3(5), C(14)-Sn(1)-O(2) 92.3(5), O(2)-Sn(1)-O(1) 154.2(2), O(2)-Sn(1)-N(1) 82.98(19), C(1)-
O(1)-Sn(1) 114.5(3), C(12)-O(2)-Sn(1) 133.8(5), C(6)-N(1)-Sn(1) 127.8(4), N(2)-N(1)-Sn(1) 116.6(4), C(1)-N(2)-N(1)
110.9(5), C(12)-C(7)-C(6) 123.1(6), O(2)-C(12)-C(7) 124.0(6), N(1)-C(6)-C(7) 127.1(7), O(1)-C(1)-N(2) 125.7(5),
C(14)-Sn(1)-N(1) 117.4(5), Sn(1)-O(2)-C(12)-C(7) 4(2), Sn(1)-N(1)-N(2)-C(1) -2.1(8), Sn(1)-N(1)-C(6)-C(7) 8(1),
Sn(1)-O(1)-C(1)-N(2) -2(1).
Insert Fig. 3
Insert Fig. 4
Symmetry operations:
(i) x, y, z; (ii) -x, y+1/2, -z+1/2; (iii) -x, -y, -z; (iv) x, -y+1/2, z+1/2
Selected bond lengths (Å), bond angles (°) and torsion angles (°): Sn(01)-C(13) 2.124(2), Sn(01)-C(19) 2.118(2),
Sn(01)-O(2) 2.1427(14), Sn(01)-N(1) 2.1631(17), Sn(01)-O(1) 2.0753(15), O(2)-C(8) 1.296(2), O(1)-C(1) 1.321(3),
N(1)-C(7) 1.290(3), N(1)-N(2) 1.397(2), N(2)-C(8) 1.309(3), C(6)-C(7) 1.435(3), C(8)-C(9) 1.460(3), C(19)-Sn(01)-
C(13) 137.85(8), C(13)-Sn(01)-O(2) 94.19(7), C(19)-Sn(01)-O(2) 93.03(7), C(13)-Sn(01)-N(1) 113.82(7), O(2)-
Sn(01)-N(1) 73.67(6), O(1)-Sn(01)-C(13) 94.56(8), O(1)-Sn(01)-C(19) 94.00(8), O(1)-Sn(01)-O(2) 157.93(6), O(1)-
Sn(01)-N(1) 84.26(6), C(8)-O(2)-Sn(01) 112.60(13), C(1)-O(1)-Sn(01) 131.26(13), C(7)-N(1)-Sn(01) 128.07(14),
N(2)-N(1)-Sn(01) 115.72(13), C(8)-N(2)-N(1) 110.71(17), C(1)-C(6)-C(7) 124.28(19), O(1)-C(1)-C(6) 123.50(18),
N(1)-C(7)-C(6) 126.21(19), O(2)-C(8)-N(2) 126.18(18), C(19)-Sn(01)-N(1) 108.07(7), Sn(01)-O(1)-C(1)-C(6) 17.5(3),
Sn(01)-N(1)-N(2)-C(8) -8.2(2), Sn(01)-N(1)-C(7)-C(6) 1.2(3), Sn(01)-O(2)-C(8)-N(2) 7.7(3).
Insert Fig. 5
3.3. Infrared spectral studies
Some of the highly informative infrared absorptions which assist in the structural
characterization of hydrazone ligands and their corresponding diorganotin(IV) derivatives are
arranged in the Experimental section (spectra are illustrated in S-1 to S-14 as supporting
information). The ligands seem to display IR spectral pattern which are expectedly peculiar to
15

ACCEPTED MANUSCRIPT
similar hydrazones [27], and so a keto-imine structure is existed in the solid state (as illustrated in
as
broad and sharp
Fig. 1). The ν(O-H) and ν(N-H) stretching vibrations appear well-distinguished
-1
bands
in the frequency range 3100-3460 cm . Well-resolved very strong and medium intensity
-1
1672-1610
bands located in the frequency range ca.
cm may be ascribed to the ν(C=O)amido and
ν(C=N) azomethine stretching vibrations. On the contrary, the IR spectra of the complexes do not
contain ν(O-H), ν(N-H) and ν(C=O)amido stretching vibrations which evidently confirm that
ligands might have lost their keto-imine form as a result of enolisation and deprotonation upon
complex formation with organotin moiety in the presence of a trimethylamine base as observed in
the other articles [4,28]. Moreover, the ν(C=N) azomethine absorption band observed in case of the
ligands is markedly shifted towards the lower frequency region 1619-1580 cm-1 upon
complexation on account of the involvement of the azomethine nitrogen in bonding to the tin
.
atom, and also the delocalization of the electron density [29] The characteristics weak ν(Sn-O)
participation of oxygen and azomethine
and ν(Sn-N) vibrational bands originated as a result of the
-1
nitrogen of the chelated ligand to the tin centers are
Me2SnLa-c complexes
observed in the region ~400-600 cm [23,28].
and symmetric ν(Sn-C) vibrational bands are
, asymmetric
In case of
seemed to display in the ranges 647-618
-1 and 583-518 cm-1, respectively, which imply a non-
cm
linear Me-Sn-Me configuration. Moreover, the well-resolved stretching ν(C-H) vibrations for the
butyl groups attached to organotin moiety in Bu2SnLa-c complexes can easily be observed between
2964 cm-1 to 2849 cm-1 [30]. Additionally, the ν(Sn-C) vibrations in Bu2SnLa-c complexes are
observed as a weak peak at ca. 509, 518 and 521 cm-1, respectively.
3.4. Multinuclear (1H, 13C, and 119Sn) NMR spectral studies
3.4.1. 1H NMR studies
1H NMR spectral data for hydrazones and their corresponding diorganotin(IV) derivatives
are arranged in the Experimental section and spectra are illustrated in S-15 to S-28 as supporting
1
information. The resonances for hydroxyl proton, -NHN= proton and aromatic protons in the H
NMR spectra of the ligands are well located, and are effortlessly assigned which in turn reflect the
ligands to exist in keto-imine form as shown in the Fig. 1. However, signals for the hydroxyl and -
NHN= protons are expectedly disappeared in 1 H NMR spectra of diorganotin(IV) derivatives as a
consequence of enolisation and deportation upon coordination of the ligands to the organotin(IV)
moiety in the enol form as reported in the similar work [10,27]. Besides, the satellites around the
16

ACCEPTED MANUSCRIPT
3
signal for azomethine proton along with significant J(119Sn-1H) coupling constant can also be
noticed on account of the coordination of the azomethine nitrogen to the tin center. Noticeable
2
well-resolved 119Sn satellites with greater J(119Sn-1H) as compared to uncomplexed Me2SnCl2
(2J(119Sn-1H = 68.7) located on both sides of the singlet for Me2Sn protons are recorded in case of
1
2
the H NMR spectra Me2SnLa-c. The greater J(119Sn-1H) coupling constant as compared to that
estimated in the uncomplexed Me2SnCl2 (2J(119Sn-1H = 68.7) is a clear indication for the higher
coordination number of the tin in solution phase [31]. In dimethyltin(IV) derivatives, CH3-Sn-CH3
angles were estimated to be ca. 145.8, 145 and 155° in (CD)3SO solution upon substitution of the
2
respective values of J(119Sn-1H) coupling constant (= 90.5, 90.0 and 96.0 Hz) in Lockhart-
Manders equation, θ = 0.0161 [2J(119Sn-1H)]2 – 1.32 [2J(119Sn-1H)] + 133.4 [32] which reflect the
non-linearity of the (CH3)2Sn moiety in the solution phase similar to the solid state. Additionally,
the CH3-Sn-CH3 angle 145° estimated for Me2SnLb seems to be consistent with that observed from
the X-ray diffraction analysis. The protons of butyl chains attached to tin in Bu2SnLa-c complexes
are recorded to exhibit their usual peculiar pattern, including a well-resolved triplet (3JH-H = 7.3 Hz)
for terminal methyl protons within δ 0.73-1.53 ppm [33]. In case of Ph2SnLa-c complexes, ortho
protons of phenyl groups attached to the tin center are appeared to be accompanied by 119Sn
1
3
satellites originated as a result of H-119Sn coupling. Herein, the values of J(119Sn-1H) coupling
constants were estimated to be larger than that found in uncomplexed Sn2PhCl2 (81.7 Hz)
indicating higher coordination number of the tin in solution phase [31].
3.4.2. 13C NMR studies
All characteristics 13C resonances of ligands and their corresponding diorganotin(IV)
derivatives are orderly arranged in a descending way in Experimental section and spectra are
illustrated in S-29 to S-42 as supporting information. The signals for all carbon resonances of
ligands are carefully detected, and duly assigned in their 13C spectra. The peaks located at 154.02-
156.44, 146.33-146.15 and 148.05-154.65 ppm for O=C (C-5), CH=N (C-6) and C-OH (C-12)
carbons of the ligands are seemed to be reasonably shifted downfield in case of diorganotin(IV)
derivatives as a consequence of the shifting of the electron-density on donor atoms to the tin center
which is consistent with the earlier reports [28,34]. Furthermore, well-resolved signals for 13C
resonances of the alkyl/aryl groups of organotin(IV) moieties comparable to those reported for
other diorganotin(IV) derivatives of the tridentate ONO dibasic ligands were successfully identified
17

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[27,35,36].
3.4.3. 119Sn NMR studies
119Sn NMR spectral data of the diorganotin(IV) derivatives executed in a non-
The
are included in the Experimental section. The 119
coordinating solvent (CDCl3)
Sn NMR spectra of
La are illustrated in Fig. 6 while those of other diorganotin(IV) derivatives are included as
R2Sn
119Sn NMR spectra of
supporting information from S-43 to S-49. It is evident form the
the
complexes that they adopt exclusively a monomeric structure
in the solution which is in accordance
with that established from single crystal X-ray diffraction analysis as there exhibit a sharp 119Sn
resonance peaks between δ 147.78-331.32 ppm. Besides, the sharp 119Sn resonance singlets in
diorganotin(IV) derivatives
are observed to be shifted appreciably upfield as compared to those
Me SnCl (+137 ppm), Bu SnCl (+122 ppm) and Ph SnCl (-32 ppm) on account of
reported for
the
2
2
,
2
2
2
2
enhancement in the co-ordination state of tin atom [31]. Additionally, these 119Sn chemical
shifts are observed to be peculiar to those acquired in case of other penta-coordinated
diorganotin(IV) derivatives [14,16,36]. Moreover, the 119Sn resonance peaks are remarkably shifted
Ph SnLa-c complexes as compared those observed in alkyl organotin(IV) analogues
upfield in
as a
2
the most prevalent anisotropic shielding effects and the pi-interactions observed in
consequence of
these cases [37].
Insert Fig. 6
3.5. Mass spectral studies
The hydrazone ligands and their corresponding diorganotin(IV) derivatives were carefully
analyzed by electrospray mass spectrometry (ESMS) technique and an attempt was made to assign
their true molecular weights. High resolution mass spectra (HRMS) in some of the cases were also
successfully obtained, indicating the expected compounds. ESI mass spectral data are listed in the
Experimental section and spectra are illustrated as supporting information form S-50 to S-71. The
ESMS spectra of the studied ligands and their diorganotin(IV) derivatives are seemed to record the
molecular adducts [M+Na]+ and [M+K]+ [38] in addition to the protonated molecular ion peaks.
Besides, some of the valuable peaks were also successfully detected at m/z values ca. 192.9, 149.9,
and 94.8 in the mass spectra of H2La and R2SnLa as a consequence of the detachment of various
18

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fragmentation species form the corresponding protonated molecular ion peaks (as shown in
scheme 2). Likewise, the mass spectra of H2Lb and R2SnLb were analyzed to contain the valuable
ions at m/z values ca. 196.8, 153.9, and 94.7 which were conveniently identified (as shown in
scheme 3). However, no any such characteristics ions with significant abundances could be
detected on account of the 100 % abundant protonated molecular ion peaks in case of R2SnLc
derivatives of H2Lc. The first fragmentation step in each diorganotin(IV) derivative was observed
to be accompanied by the prompt elimination of the R2Sn moiety attached to the complexed ligand
from its corresponding protonated molecular ion. The fragmentation mechanisms of
diorganotin(IV) derivative of H2La and H2Lb invariably include a common fragmentation pattern
(as shown in scheme 2 and scheme 3). The most peculiar pattern as a result of the natural
abundances of Sn isotopes (120Sn, 118Sn, 116Sn etc.) in Sn enriched species could tangibly be seen in
the mass spectra of the diorganotin(IV) derivatives [39].
Insert Scheme 3
Insert Scheme 4
3.6. Thermal studies
All diorganotin(IV) derivatives were analyzed using thermogravimetric techniques (TG-DTA-
DTG) in order to explore their thermal behaviour. The thermal analysis data so extracted were
S-72 to S-77)
compiled in table S-1, and incorporated along with the pertaining thermograms (from
a
as supporting information.
Figures 7-10 illustrate the pyrolysis curves for R2SnL derivatives which
seem to involve a common thermal decomposition pattern i.e. pyrolysis via two decomposition
steps. In case of Me2SnLa, step I (20-327 °C) involves a % weight loss of 52.00 which may be
ascribed to the loss of the two methyl groups attached to the Sn atom (C2H6) and a fraction of the
ligand moiety (C12H10O2) (calcd. % weight loss: 53.14) whereas the step II (327-464 °C) exhibits a
% weight loss of 28.20 as a result of the loss of the remaining fraction of the ligand (CN2O3/2) and
the partial sublimation of the tin metal (1/2Sn) (calcd. % weight loss: 30.3). Bu2SnLa seems to
undergo decomposition via step I (30-321 °C, % weight loss: 44.00) and step II (321-468 °C, %
weight loss: 31.70) which presumably be due to the loss of the two butyl groups attached to the Sn
atom (C8H18) and a fraction of the ligand moiety (C7H6O) (calcd. % weight loss: 44.87), and the
loss of the remaining fraction of the ligand (C6H4N2O3) (calcd. % weight loss: 30.96). The
pyrolysis of Ph2SnLa includes loss of the two phenyl groups attached to the Sn atom (C6H10) and a
19

ACCEPTED MANUSCRIPT
fraction of the ligand moiety (CH3O) (calcd. % weight loss: 34.86) in the step I (28-343 °C, %
weight loss: 34.9) followed by the subsequent loss of the remaining ligand moiety (C12H8N2O3)
(calcd. % weight loss: 35.99) in step II (327-482 °C, % weight loss: 35.99). The decomposition of
Oct2SnLa consists of loss of the two octyl chains attached to the Sn atom (calcd. % weight loss:
37.46) in the first step (calcd. % weight loss: 36.5) followed by the elimination of the whole ligand
moiety (C13H11N2O3) (calcd. % weight loss: 40.07) in step II (327-482 °C, % weight loss: 38.3).
The thermal behaviour of Me2SnLb and Ph2SnLb derivatives seems not to be consistent as
perceived from the figures S-72 and S-73. The first step (20-458 °C, % weight loss: 83.7) for
Me2SnLb includes the loss of two methyl groups attached to the Sn atom (C2H6) along with the
whole ligand moiety (C12H7ClN2O3/2) followed by sublimation of the tin atom (calcd. % weight
loss: 83.63). Herein, second step (458-642 °C, % weight loss: 6.3) may be considered on account
of the sublimation of the tin element (25-356 °C, % weight loss: 6.55). However, the pyrolysis
curve of Ph2SnLb involves a loss of a fraction of the ligand moiety (C11H8ClO) (calcd. % weight
loss: 35.77) in step I (25-356 °C, % weight loss: 36.1), and a subsequent loss of two phenyl groups
attached to the Sn atom (C12H10) along with the remaining fraction of the ligand (calcd. % weight
loss: 39.24) in the step II (356-570°C, % weight loss: 39.6). The first step (27-387 °C, % weight
loss: 62.6) in the pyrolysis of Me2SnLc may be ascribed to the elimination of both methyl groups
attached to the Sn atom (C2H6) along with the whole ligand moiety (C12H7N3O3) (calcd. % weight
loss: 64.24) whereas the second step (387-458 °C, % weight loss: 12.8) is attributed to the partial
sublimation of the tin element (calcd. % weight loss: 11.90). The pyrolysis curves of Bu2SnLc and
Ph2SnLc, however consists of three decomposition steps. In the first step (36-293 °C, % weight
loss: 15.6) of Bu2SnLc, a fraction of the ligand (C5H3O) may be considered to evolve out (calcd. %
weight loss: 15.63). The second step (293-447 °C, % weight loss: 40.5) involve the elimination of
one of the butyl group (C4H9) attached to the Sn atom along with the remaining fraction of the
ligand (C7H4N2O2) (calcd. % weight loss: 40.54). Finally, in the third step (447-507 °C, % weight
loss: 15.9), the second butyl group (C4H9) and one molecule of oxygen are evolved out (calcd. %
weight loss: 17.60). The pyrolysis curves of Ph2SnLc may be divided in to three decomposition
steps viz., step I (26-327 °C, % weight loss: 15.6), step II (327-438 °C, % weight loss: 32.0) and
step III (438-486 °C, % weight loss: 23.5) which are probably ascribed to the loss of a fraction of
the ligand moiety (C5H3O) (calcd. % weight loss: 14.48), the loss of the remaining fraction of the
ligand moiety (C7H4N3O3) (calcd. % weight loss: 32.61) and the two phenyl groups attached to the
20

ACCEPTED MANUSCRIPT
Sn atom (C12H10) (calcd. % weight loss: 28.23) respectively. The pyrolysis of Oct2SnLc consists of
two steps; 28-300 °C and 300-500 °C which may be attributed to the loss of a fraction of the ligand
moiety (obsd. % weight loss: 15.43, calcd. % weight loss: 15.38) and the loss of the two octyl
chains attached to the Sn atom along with the remaining fraction of the ligand moiety (C7H4N2O2)
(obsd. % weight loss: 60.42, calcd. % weight loss: 60.57) respectively. In the later stages of
pyrolysis of diorganotin(IV) derivatives, the characteristic broad exothermic peaks were also
noticed in their DTA curves which infer the oxidation of tin metal content to tin dioxide as residue,
comparable to our previous works [40-42].
Insert Fig. 7
Insert Fig. 8
Insert Fig. 9
Insert Fig. 10
4. Conclusion
acylhydrazones viz., N'-(2-hydroxy-3-
In a nut shell, facile synthesis and chracterization of three
methoxybenzylidene)furan-2-carbohydrazide, N'-(5-chloro-2-hydroxy-benzylidene)furan-2-carbo-
hydrazide and N'-(2-hydroxy-5-nitrobenzylidene)furan-2-carbohydrazide and their
have been described.
eleven new
Two mononuclear complexes, Me2SnLb and
diorganotin(IV) derivatives
Ph2SnLb have been investigated by single crystal X-ray diffraction to adopt a highly distorted
square-pyramidal geometry (SP) wherein the imine nitrogen preferably occupies the apical site
whereas the more electronegative enolic and phenolic oxygen atoms of the tridentate chelating
ligand and two carbon atoms of the methyl/phenyl groups of the organotin(IV) moiety,
[R2Sn(IV)]2+ align themselves equatorially around the five-coordinated tin center in a square plane.
Thermal stability and decomposition trends of diorganotin(IV) derivatives indicate almost same
pattern in the most of the cases which involves the loss of organic groups attached to tin followed
by the decomposition of the ligand moiety.
Acknowledgements
The authors are thankful to the Head, Institute Instrumentation Centre (IIC), Indian Institute of
Technology Roorkee, Roorkee, India for providing facilities to carry out single crystal X-ray study
and thermal studies. One of the authors (Mr. Sundeep Kumar) is thankful to All India Council for
21

ACCEPTED MANUSCRIPT
Technical Education (AICTE), New Delhi, India, for financial support under quality improvement
programme (QIP).
Appendix A. Supplementary material
CCDC 1477450 and CCDC 1496981 contain the supplementary crystallographic data for this
paper. These data can be obtained free of charge from The Cambridge Crystallographic Data
1
Centre via www.ccdc.cam.ac.uk/data_request/cif. A supplementary file contains IR, H, 13C and
119Sn NMR, and ESMS spectra, TG-DTA-DTG thermograms of all compounds.
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Legends of Figures and Schemes
Fig. 1. Structures of acylhydrazone Schiff base ligands along with the atomic labeling scheme for
nmr assignments.
Fig. 2. ORTEP diagram of Me2SnLb along with the adopted non-hydrogen atoms labeling scheme.
The ellipsoids are displayed at 30% probability level and hydrogen atoms are not included for
clarity.
Fig. 3. The molecular packing of viewed Me2SnLb along the crystallographic axis ‘b’.
Fig. 4. ORTEP diagram of Ph2SnLb along with the adopted non-hydrogen atoms labeling scheme.
The ellipsoids are displayed at 30% probability level and hydrogen atoms are not included for
clarity.
Fig. 5. The molecular packing of viewed Ph2SnLb along the crystallographic axis ‘b’.
Fig. 6. 119Sn NMR spectra of R2SnLa complexes.
Fig. 7. TG-DTA-DTG thermograms of Me2SnLa.
Fig. 8. TG-DTA-DTG thermograms of Bu2SnLa.
Fig. 9. TG-DTA-DTG thermograms of Ph2SnLa.
Fig. 10. TG-DTA-DTG thermograms of Oct2SnLa.
Scheme 1. Systematic numbering scheme of the organic groups attached to Sn atom in
diorganotin(IV) derivatives.
Scheme 2. Systematic synthetic route for acylhydrazone and their corresponding diorganotin(IV)
derivatives.
(2-hydroxy-3-
Scheme 3. A plausible fragmentation mechanism for dimethyltin(IV) complex of
methoxybenzylidene)furan-2-carbohydrazide
.
ligand
N'-(5-chloro-2-
Scheme 4. A plausible fragmentation mechanism for dimethyltin(IV) complex of
hydroxybenzylidene)furan-2-carbohydrazide.
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Table 1
Crystallographic data and structure refinement parameters for Me2SnLb and Ph2SnLb.
Me2SnLb
Ph2SnLb
Empirical formula
Formula weight
Crystal system
Space group
C12H13ClN2O3Sn
411.42
monoclinic
C24H17ClN2O3Sn
535.56
monoclinic
'P 21'
'P 21/c'
a (Å) = 6.433 (5)
b (Å) = 7.509 (5)
c (Å) = 15.817 (5)
a (Å) = 8.8238 (4)
b (Å) = 18.6665 (8)
c (Å) = 13.3236 (6)
β (°) = 95.873 (5)
β (°) =101.0040 (10)
V(Å3)
760.0 (8)
2
1.798
1.867
2154.17 (17)
4
1.651
1.339
Z
d (g cm-3)
µ (Mo k α) (mm-1)
F(000)
404
1064
T(K)
293 (2)
0.71073
3.37-26.67
3374
11339
-7 ≤ h ≤ 8,
293 (2)
Wavelength, λ (Å)
θ Minimum-maximum(°)
Independent reflections/ total reflections
Reflections collected
Limiting indices
0.71073
1.901-28.303
5356
28724
-11 ≤ h ≤ 11,
-10 ≤ k ≤ 9,
-20 ≤ l ≤ 21
-24 ≤ k ≤ 21,
-17 ≤ l ≤ 17
Data/restraints/parameters
Final R indices [I˃2σ(I)]
3708/1/194
R1 = 0.0324
wR2 = 0.0864
R1 = 0.0373
wR2 = 0.0920
1.104, -1.055
1.119
5356/0/284
R1 = 0.0248
wR2 = 0.0571
R1 = 0.0333
wR2 = 0.0618
0.450, -0.474
1.089
R indices (all data)
Largest diff. peak and hole (e.A-3)
Goodness-of-fit (GOF) on F2
Flack Parameter
0.143(14)
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