Measurement and correlation of the solubility of tin compounds and β-diketimine in selected solvents

Article abstract of DOI:10.1016/j.molliq.2019.111784

The solubility of organotin compounds under inert atmosphere plays a significant role in homogeneous catalysis process; however, no such study has been reported. The solubilities of dimethyltin dichloride (1), stannous chloride (2), β-diketiminato ligand

Full text of DOI:10.1016/j.molliq.2019.111784

Journal of Molecular Liquids 296 (2019) 111784
Contents lists available at ScienceDirect
Journal of Molecular Liquids
journal homepage: www.elsevier.com/locate/molliq
Measurement and correlation of the solubility of tin compounds and
b-diketimine in selected solvents
Jiahui Wang, Xiaoli Ma**, Yi Ding, Yan Wang, Zhi Yang*
School of Chemistry and Chemical Engineering, Beijing Institute of Technology, 100081, Beijing, PR China
a r t i c l e i n f o
a b s t r a c t
Article history:
The solubility of organotin compounds under inert atmosphere plays a significant role in homogeneous
catalysis process; however, no such study has been reported. The solubilities of dimethyltin dichloride
Received 10 September 2019
Received in revised form
17 September 2019
Accepted 20 September 2019
Available online 9 October 2019
(1), stannous chloride (2),
b-diketiminato ligand LH (3) (L ¼ HC(CMeNAr)2, Ar ¼ 2,6-Et2C6H3), and tin (II)
compound [LSnCl] (4) in six organic solvents were measured using a static analytic method from 268.15 K
to 313.15 K under a purified nitrogen atmosphere to select the optimum solvent for a homogeneous
reaction and recrystallization. The difference in solubility can be attributed to molecular structure, co-
ordination bonding, and molecular polarity. Six commonly used thermodynamic models were used to
correlate the experimental solubility data. Some models show a great correlation with a low value of
average absolute deviation (AAD). In addition, the solubility parameter of solute, partial molar excess
enthalpies at infinite dilution, and thermodynamic properties were calculated to study the dissolution
behavior in more depth.
Keywords:
Organotin
Solubility
Inert atmosphere
Solideliquid equilibrium
Thermodynamic properties
© 2019 Elsevier B.V. All rights reserved.
1. Introduction
by changing the amide moiety, thus making them ideal for catalytic
applications [5,6]. Organotin compounds stabilized with b-diketi-
Organotin compounds, a type of organometallics where a car-
bon atom is directly connected with a tin atom, are widely used in
catalysis chemistry, synthetic organic chemistry, pharmaceutical
chemistry, and other fields. These compounds are sensitive to
moisture and oxygen. Since the late 1970s and early 1980s, orga-
notin compounds have been used in catalytic synthesis because of
mild reaction conditions, high yield, fast reaction rate, nontoxic
catalysts that can be easily separated from the product, and
noncorrosive to the reaction vessel [1]. Compared with inorganic
compounds, the greatest advantage of organotin compounds is the
greater solubility in organic solvents, making them suitable for use
in homogeneous catalysis. For example, organotin compounds are
well-known reducing agents for unsaturated molecules such as
ketones and alkenes in homogeneous catalytic reactions [2,3]. In
minato ligand have been extensively evaluated to activate small
molecules. Recently, our group reported some new organotin
compounds bearing
b-diketiminato ligand LH such as LSnMe3,
LSnCl, LSnCl3, and LSnMe2Cl [7e10].
Solvent effect, also known as “solvation,” refers to the effect of
physical and chemical properties of a solvent on the equilibrium of
reaction and the rate of reaction in a liquidephase reaction. In
many homogeneous reactions involving the main group organo-
metallics, the solvent effect mainly influences the structure and
reactivity of main group metal compounds [11]. Therefore, it is very
important to use suitable solvents for homogeneous reactions, thus
increasing the efficiency of reactions to a considerable extent. At
the same time, during crystallization separation, the choice of
solvent is not only related to the purity of solute, but also signifi-
cantly affects the size, morphology, and crystallization mode of
solute crystal. The solubility data can be used to better understand
the reasons for different solubilities of the same substance in
different solvents, thus providing a theoretical basis and reference
standards for future experiments and synthesis. However, com-
plete and accurate solubility data and relatively perfect thermo-
dynamic models for organotin compounds in common organic
solvents are not available. Therefore, it is essential to measure the
solubility of organotin compounds under an inert atmosphere in
selected solvents to fill the gap in basic physical properties and
recent years, b-diketimine [4] has also attracted much attention
because the core skeleton of this type of ligand has an alternating
single bond double bond system, which is relatively more affected
by the metal properties when reacting with organometallic pre-
cursors. These ligands can be used to easily adjust the steric feature
* Corresponding author.
** Corresponding author.
E-mail addresses: maxiaoli@bit.edu.cn (X. Ma), zhiyang@bit.edu.cn (Z. Yang).
https://doi.org/10.1016/j.molliq.2019.111784
0167-7322/© 2019 Elsevier B.V. All rights reserved.

2
J. Wang et al. / Journal of Molecular Liquids 296 (2019) 111784
understand the reasons for difference in solubility from the
perspective of molecular structure, coordination bonding, and
molecular polarity. This will promote further development in this
field. Furthermore, the optimum solvent for participating in ho-
mogeneous reactions and growing crystals can be determined by
comparing the solubility of same solute in different solvents.
In this study, the solubilities of dimethyltin dichloride (1)
(C2H6SnCl2, molecular weight 219.68, CAS, 753-73-1) in four pure
organic solvents (n-hexane, toluene, ether, and tetrahydrofuran),
stannous chloride (2) (SnCl2, molecular weight 189.62, CAS, 7772-
99-8) in five pure organic solvents (toluene, ether, tetrahydrofuran,
a Mbraun MB 150-GI glove box. The solvent was pretreated to
strictly ensure an anhydrous and anaerobic environment. The van’t
Hoff equation is an equation that assumes the system is ideal. This
model can only be used when it comes to poorly soluble solutes
where solute-solute interactions are negligible. The solubility of
compounds 1, 2, 3, and 4 is not low, so the solute-solute interactions
are significant, and the results of the calculations developed taking
into account the activity coefficients are truly uncertain. Especially
for tin chloride. Therefore, van’t Hoff equation were not used to
correlate the experimental solubility data in this study. The
experimental solubility data were correlated with several
commonly used thermodynamic models such as the Apelblat,
methanol, and ethanol),
b-diketiminato ligand LH (3)
(L ¼ HC(CMeNAr)2, Ar ¼ 2,6-Et2C6H3, C25H34N2, molecular weight
362.55, CAS, 257874-89-8, Fig. 1) in six pure organic solvents (n-
hexane, toluene, ether, tetrahydrofuran, methanol, and ethanol)
and tin (II) compound [LSnCl] (4) (C25H33N2SnCl, molecular weight
515.67, CAS, 2226823-29-4, Fig. 2) in four pure organic solvents (n-
hexane, toluene, ether, and tetrahydrofuran) were measured using
a static analytic method from 268.15 K to 313.15 K under atmo-
spheric pressure. Because organotin compounds are very sensitive
to moisture and oxygen, all the operations were carried out under a
purified nitrogen atmosphere by using the Schlenk technique or in
polynomial, lh, Wilson, NRTL, and UNIQUAC equations to text the
applicability of these models to the experimental system. The sol-
ubility parameter of solute and partial molar excess enthalpy at
infinite dilution were deduced using the ScatchardeHildebrand
model. To further evaluate the abovementioned dissolution
behavior, the thermodynamic properties including DmixG, DmixH,
and DmixS were also calculated.
2. Experimental section
2.1. Materials
Compounds 1 and 2 were purchased from Beijing Saen Chemical
Co., Ltd. (mass fraction purity >98%). Analytical reagent grade n-
hexane, toluene, ether, tetrahydrofuran, methanol, and ethanol
(mass fraction purity >99.5%) used in this study were purchased
from Beijing Chemical Reagent Co., Ltd. Among them, n-hexane,
toluene, ether and tetrahydrofuran were pretreated by refluxing
them over a suitable desiccant and distilling them before use. More
details about the chemicals used in this study are shown in Table 1.
Fig. 1. Molecular structure of compound 3.
2.2. Apparatus and procedure
The melting point and enthalpy of fusion were measured using a
DSC Q600 differential scanning calorimeter (DSC) under flowing
nitrogen at a heating rate of 10 K/min. NMR spectra were recorded
with a Bruker Ascend II 400 spectrometer. Thermogravimetric
analysis (TGA) was carried out using an SDT Q600 thermogravi-
metric analyzer at a heating rate of 10 K/min from 298.15 K to
823.15 K under nitrogen [12].
In the solubility measurement, the experimental apparatus in-
cludes a thermostatic stirring bath for stirring the solution and
maintaining the temperature within 0.1 K. An electronic analytical
balance with an uncertainty of 0.001 g was used to measure the
mass of solvent, Schlenk tubes, and Schlenk bottles. All the opera-
tions were carried out under a purified nitrogen atmosphere using
the Schlenk techniques or in a Mbraun MB 150-GI glove box. The
glass instruments used in the experiment were washed in advance
and dried in an electric thermostatic drying oven at 120 ꢀC for at
least 2 h to strictly ensure the anhydrous and anaerobic
environment.
Fig. 2. Crystal structure of compound 4.
Table 1
Information of chemicals used in this study.
Chemical name
CAS number
Source
Mass fraction purity
n-hexane
toluene
ether
tetrahydrofuran
methanol
ethanol
dimethyltin dichloride
stannous chloride
110-54-3
108-88-3
60-29-7
109-99-9
67-56-1
64-17-5
753-73-1
7772-99-8
Beijing Chemical Reagent Co., Ltd.
Beijing Chemical Reagent Co., Ltd.
Beijing Chemical Reagent Co., Ltd.
Beijing Chemical Reagent Co., Ltd.
Beijing Chemical Reagent Co., Ltd.
Beijing Chemical Reagent Co., Ltd.
Beijing Saen Chemical Co., Ltd.
Beijing Saen Chemical Co., Ltd.
0.995
0.995
0.995
0.995
0.995
0.995
0.98
0.98

J. Wang et al. / Journal of Molecular Liquids 296 (2019) 111784
3
2.3. Synthesis
and then the filtrate was concentrated to 8 mL and stored in a
refrigerator at ꢁ7 ꢀC overnight, affording yellow crystals. The
preparation process is shown in Fig. 4.
Compound 3 was prepared according to the literature [13].
Acetylacetone was reacted with twice the molar amount of 2,6-
diethylaniline. An appropriate amount of HCl was added to cata-
lyze the reaction, and a slight excess of 2,6-diethylaniline was used
to ensure complete reaction. Ligand LH was obtained as a white
powder, and the preparation process is shown in Fig. 3.
2.4. Characterization
Compound 4 was characterized by our group [7]: 1H NMR
(400 MHz, CDCl3, 298 K, TMS):
d 7.19e7.08 (m, 6 H, C6H3), 5.25 (s,
Compound 4 was reported by our group [7]. 2 mmol of n-BuLi
(2.5 mol/L hexane solution) was added dropwise to a precooled
(ꢁ78 ꢀC) solution of LH (0.725 g, 2 mmol). The mixture was stirred
at room temperature. Stirring was continued for 6 h. A solution of
SnCl2 (0.379 g, 2 mmol) in 10 mL toluene was added dropwise to
the precooled (0 ꢀC) mixture. The reaction mixture was then stirred
vigorously at room temperature for 24 h. The solution was filtered,
1 H, CH), 2.82 (m, 4 H, CH2Me), 2.47 (m, 4 H, CH2Me), 1.75 (s, 6 H,
CMe), 1.18 (t, 12 H, CH2Me) ppm. 13C NMR (101 MHz, CDCl3, 298 K,
TMS):
d 164.54 (NCMe), 141.65, 139.40, 136.79, 124.90 (ipso-, o-, p-,
m-C), 99.22 (g-CH), 23.91 (CH2Me), 22.62 (CMe), 13.45 (CH2Me)
ppm.
The results of DSC and TGA measurements of compounds are
shown in Figs. 5 and 6, respectively. The melting points of com-
pounds 1, 2, 3, and 4 are 378.58 K, 504.45 K, 354.39 K, and 451.37 K,
respectively. The uncertainty of melting point for all the com-
pounds is 0.26 K. The enthalpy of fusion of compound 1 is 31.96 kJ/
mol, and the uncertainty is 0.26%. The enthalpy of fusion of com-
pound 2 is 22.27 kJ/mol, and the uncertainty is 0.32%. The enthalpy
of fusion of compound 3 is 24.37 kJ/mol, and the uncertainty is
0.57%. The enthalpy of fusion of compound 4 is 27.65 kJ/mol, and
the uncertainty is 0.71%. The DSC and TGA curves were analyzed
using Stare software. The results of TGA and DSC analyses show that
compounds 1, 2, 3, and 4 have excellent thermal stability [12].
Fig. 3. Preparation of compound 3.
2.5. Solubility measurements
Because organotin compounds are very sensitive to moisture
and oxygen, all the operations were carried out under a purified
nitrogen atmosphere using Schlenk techniques or in a Mbraun MB
150-GI glove box.
Fig. 4. Preparation of compound 4.
First, an excess amount of compound 1 was added to a vial with
Fig. 5. Experimental heat Q flow from the DSC measurement: (a) compound 1, (b) compound 2, (c) compound 3, (d) compound 4.

4
J. Wang et al. / Journal of Molecular Liquids 296 (2019) 111784
Fig. 6. TGA thermogram under nitrogen: (a) compound 1, (b) compound 2, (c) compound 3, (d) compound 4.
a certain amount of solvent in a glove box. The vial was then placed
in a thermostatic stirring bath at the selected temperature. After
stirring for at least 5 h until the solution was saturated, the ther-
mostatic stirring bath was stopped, and the solution was stand for
at least 10 h until it was clear. A certain amount of the upper clear
solution was added to another preweighed measuring vial (m1) by
xexp ꢁ xcalc
RD ¼
(3)
xexp
The superscripts “exp” and “calc” represent experimental solu-
bility and calculated values [15].
using an injection syringe with a 0.22 mm membrane. After adding
3. Thermodynamic models
the solution, the vial (m2) was quickly closed and weighed. After a
suitable amount of liquid nitrogen was added to the Dewar flask,
the vial was connected to a Schlenk tube, and the solution in the
vial was pumped using a vacuum pump for at least half an hour.
After the solvent in the vial completely evaporated, the vial was
reweighed (m3). The method for measuring the solubility of com-
pounds 2, 3, and 4 is the same as that for compound 1. The solid
concentration of the solute in mole fraction can be defined using
Eq. (1).
3.1. Apelblat equation
Apelblat equation is widely used for the correlation of
solideliquid phase equilibrium data. The solubility equation can be
written as Eq. (4):
lnx ¼ A þ B=T þ C ln T
(4)
where x is the mole fraction of solute. T is the absolute temperature.
A, B, and C are empirical parameters. They were determined by
solubility fitting [16]. The mole fraction solubilities x of compounds
1, 2, 3, and 4 in selected solvents and the smoothed data calculated
from Eq. (4) are shown in Table 2. The activity coefficient of solute
and RD are also shown in Table 2. The results show that Eq. (4) can
be used to correlate the solubility data, and the solubilities of
compounds 1, 2, 3, and 4 in selected solvents increase with
increasing temperature.
ðm3 ꢁ m1Þ=M1
x1
¼
(1)
ðm3 ꢁ m1Þ=M1 þ ðm2 ꢁ m3Þ=M2
where M1 and M2 are the molecular weights of solute and organic
solvent, respectively.
The following equilibrium Eq. (2) can be used to calculate an
approximation of activity coefficient of solute (g1).
ꢀ
ꢁ
3.2. Polynomial equation
Dfus
H
x
1g1 ¼ exp
ð1 = Tm ꢁ 1 = TÞ
(2)
R
Polynomial empirical equation is based on the assumption that
the solubility of a substance continuously changes with tempera-
ture under constant pressure. The basic equation can be expressed
as Eq. (5):
where x1 is the solid concentration of solute in mole fraction in the
saturated solution. R is the gas constant. Tm is the melting point of
solute. DfusH is the fusion enthalpy and should be determined by
DSC analysis. T is the absolute temperature [14]. The relative de-
viation (RD) is used to evaluate the difference between the
measured and correlation results.
x1 ¼ a þ b T þ c T2 þ d T3
(5)

J. Wang et al. / Journal of Molecular Liquids 296 (2019) 111784
5
Table 2
Table 2 (continued )
Experimental and calculated mole fraction solubility (x) and activity coefficients (
of compounds 1, 2, 3, and 4 in selected solvent.
g)
solvent
T/K
100xexp
100xcal
g
100RD
278.15
283.15
288.15
293.15
298.15
303.15
308.15
313.15
27.091
31.859
36.227
39.914
42.929
44.925
45.848
46.039
26.904
31.702
36.156
39.999
43.006
45.023
45.971
45.852
0.0491
0.0495
0.0513
0.0545
0.0591
0.0655
0.0741
0.0847
0.689
0.495
0.195
ꢁ0.213
ꢁ0.181
ꢁ0.219
ꢁ0.268
0.407
solvent
T/K
100xexp
100xcal
g
100RD
dimethyltin dichloride
n-hexane
303.15
0.348
0.576
0.836
1.086
1.268
1.726
2.113
2.620
3.140
3.765
4.648
5.529
6.579
7.807
2.427
2.892
3.416
4.020
4.697
5.492
6.387
7.338
16.267
17.901
19.454
21.314
23.265
25.398
28.166
30.616
33.108
36.812
0.349
0.574
0.836
1.087
1.268
1.719
2.118
2.593
3.157
3.823
4.604
5.518
6.581
7.813
2.425
2.887
3.418
4.023
4.711
5.489
6.366
7.350
16.319
17.824
19.480
21.300
23.302
25.499
27.912
30.559
33.462
36.644
22.9493
17.0559
14.3269
13.3821
13.8175
1.1506
1.2099
1.2459
1.3155
1.3775
1.3903
1.4457
1.4925
1.5349
0.6291
0.6863
0.7484
0.8116
0.8794
0.9442
1.0115
1.0891
0.0939
0.1109
0.1314
0.1531
0.1775
0.2042
0.2294
0.2610
0.2965
0.3255
ꢁ0.281
0.219
ꢁ0.012
ꢁ0.055
0.021
308.15
313.15
318.15
323.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
308.15
313.15
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
308.15
313.15
toluene
0.392
b-diketimine
n-hexane
ꢁ0.202
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
308.15
313.15
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
308.15
313.15
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
308.15
313.15
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
308.15
313.15
3.726
4.782
6.088
7.689
3.726
4.782
6.088
7.689
1.8763
1.7859
1.7013
1.6226
1.5489
1.4798
1.4152
1.3544
1.2973
1.2436
0.4759
0.5280
0.5803
0.6351
0.6922
0.7516
0.8099
0.8697
0.9265
0.9823
0.9546
0.8885
0.8428
0.8194
0.8135
0.8255
0.8479
0.8743
0.5211
0.5802
0.6333
0.6722
0.7011
0.7224
0.7436
0.7744
235.8891
228.9187
222.4094
215.4332
207.0922
198.7129
190.5651
179.4905
167.3062
152.6756
44.3534
45.8388
47.0031
48.4384
47.4391
48.0823
44.1454
41.5028
39.1383
34.8830
0.001
1.009
ꢁ0.004
ꢁ0.543
ꢁ1.536
0.937
0.007
ꢁ0.001
ꢁ0.003
0.001
9.640
9.640
0.203
12.002
14.842
18.239
22.276
27.050
14.691
16.175
17.848
19.645
21.571
23.631
25.933
28.403
31.192
34.245
7.324
12.002
14.842
18.239
22.276
27.050
14.723
16.202
17.821
19.592
21.528
23.643
25.951
28.468
31.211
34.199
7.381
ꢁ0.029
ꢁ0.076
0.065
ꢁ0.003
0.003
ether
0.000
0.000
ꢁ0.218
ꢁ0.165
0.154
0.172
ꢁ0.057
ꢁ0.063
ꢁ0.304
0.043
toluene
0.273
0.202
0.336
ꢁ0.155
ꢁ0.316
0.433
ꢁ0.049
ꢁ0.067
ꢁ0.228
ꢁ0.061
0.136
ꢁ0.778
ꢁ0.322
0.338
0.488
0.352
ꢁ0.278
ꢁ0.532
0.311
tetrahydrofuran
ꢁ0.133
0.063
ꢁ0.155
ꢁ0.400
0.901
ether
9.611
9.642
12.289
15.227
18.355
21.514
24.771
28.255
13.417
14.719
16.354
18.561
21.297
24.587
28.248
31.899
0.030
0.037
0.047
0.058
0.072
0.089
0.110
0.138
0.173
12.247
15.152
18.290
21.574
24.903
28.167
13.186
14.749
16.595
18.771
21.337
24.364
27.934
32.149
0.028
0.035
0.045
0.057
0.072
0.090
0.113
0.141
0.175
0.184
ꢁ1.070
0.456
stannous chloride
toluene
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
308.15
313.15
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
308.15
313.15
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
308.15
313.15
268.15
273.15
0.111
0.120
0.127
0.143
0.158
0.187
0.215
0.258
0.330
0.439
0.608
0.624
0.656
0.722
0.816
0.925
0.117
0.119
0.126
0.137
0.155
0.181
0.217
0.266
0.336
0.433
0.613
0.623
0.657
0.715
0.803
0.928
8.3768
9.3026
10.4967
10.9970
11.7742
11.6219
11.7854
11.4040
10.2844
8.8954
1.5266
1.7855
2.0276
2.1823
2.2761
2.3518
2.3558
2.1773
0.0980
0.1009
0.1051
0.1091
0.1128
0.1177
0.1221
0.1286
0.1291
0.1324
0.0382
0.0402
0.0431
0.0460
0.0489
0.0517
0.0543
0.0569
0.0593
0.0613
0.0542
0.0505
ꢁ5.296
0.872
0.903
4.161
1.576
tetrahydrofuran
1.724
ꢁ0.203
ꢁ1.473
ꢁ1.130
ꢁ0.189
0.908
3.422
ꢁ0.664
ꢁ3.288
ꢁ1.694
1.318
1.112
ꢁ0.783
methanol
6.858
ether
ꢁ0.715
5.462
3.663
1.872
0.569
ꢁ0.789
ꢁ2.314
ꢁ2.197
ꢁ1.195
1.748
0.182
ꢁ0.165
0.939
1.542
ꢁ0.299
ꢁ2.248
0.936
ꢁ1.299
ꢁ0.265
0.461
0.752
0.587
0.294
ꢁ0.272
ꢁ0.272
ꢁ0.964
0.678
1.077
1.351
9.518
1.101
1.339
9.642
tetrahydrofuran
0.220
0.158
0.186
0.220
0.258
0.315
0.369
0.476
0.216
0.162
0.186
0.217
0.257
0.310
0.379
0.470
11.015
12.666
14.455
16.372
18.465
20.710
23.298
25.962
29.539
24.290
27.755
30.825
34.284
37.982
42.126
46.688
51.744
57.235
63.613
17.116
22.083
11.044
12.608
14.347
16.276
18.410
20.766
23.361
26.212
29.339
24.656
27.515
30.669
34.143
37.966
42.167
46.779
51.836
57.376
63.439
17.408
22.050
ethanol
ꢁ2.648
0.422
1.702
0.154
1.480
ꢁ2.684
1.187
0.595
0.738
0.964
0.590
0.749
0.960
0.882
ꢁ1.400
methanol
ꢁ1.506
0.423
0.865
LSnCl
n-hexane
0.506
0.410
0.043
ꢁ0.096
ꢁ0.194
ꢁ0.178
ꢁ0.247
0.273
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
308.15
313.15
0.068
0.084
0.101
0.122
0.146
0.174
0.207
0.244
0.286
0.335
0.069
0.084
0.101
0.122
0.146
0.174
0.207
0.244
0.286
0.335
9.5153
9.7722
ꢁ0.224
ꢁ0.052
0.059
0.098
0.085
10.0234
10.2706
10.5121
10.7470
10.9717
11.1838
11.3759
11.5551
0.031
ꢁ0.027
ꢁ0.068
ꢁ0.026
0.034
ethanol
ꢁ1.705
0.151
(continued on next page)

6
J. Wang et al. / Journal of Molecular Liquids 296 (2019) 111784
Table 2 (continued )
solvent
3.5. NRTL model
T/K
100xexp
100xcal
g
100RD
In 1968, based on the concept of partial composition, Renon and
Prausnitz proposed the NRTL model suitable for partially miscible
and fully miscible systems. The basic equation can be expressed as
follows:
toluene
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
308.15
313.15
268.15
273.15
278.15
283.15
288.15
293.15
298.15
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
308.15
313.15
1.351
1.642
1.978
2.371
2.820
3.339
3.943
4.608
5.342
6.186
1.225
1.626
2.087
2.557
3.085
3.648
4.273
1.662
1.888
2.190
2.618
3.232
4.081
5.274
6.818
8.702
10.471
1.347
1.639
1.980
2.374
2.827
3.345
3.934
4.599
5.348
6.186
1.245
1.623
2.061
2.554
3.093
3.667
4.261
1.486
1.809
2.217
2.734
3.392
4.229
5.298
6.666
8.419
10.671
0.4819
0.4975
0.5141
0.5297
0.5461
0.5614
0.5750
0.5915
0.6097
0.6255
0.5312
0.5025
0.4873
0.4911
0.4991
0.5139
0.5306
0.3917
0.4326
0.4642
0.4797
0.4764
0.4594
0.4300
0.3997
0.3742
0.3695
0.295
0.172
ꢁ0.094
ꢁ0.119
ꢁ0.256
ꢁ0.168
0.248
"
#
t21G221
ðx1 þ x2G21Þ2
t12G12
ðx2 þ x1G12Þ2
lng1 ¼ x22
þ
(10)
0.182
ꢁ0.121
ꢁ0.007
ꢁ1.555
0.196
1.241
0.129
ꢁ0.266
ꢁ0.534
0.295
10.597
4.215
ꢁ1.224
ꢁ4.453
ꢁ4.932
ꢁ3.623
ꢁ0.459
2.243
ꢆ
ꢇ
ether
Gij ¼ exp
ꢁ
aijtij
(11)
(12)
gij ꢁ gjj
D
gij
RT
tij
¼
¼
RT
where aij is a parameter related to the nonrandomness of solution,
and the value is selected as 0.3. gij represents the binary cross-
tetrahydrofuran
D
interaction parameters and determined by solubility fitting [21].
3.6. UNIQUAC model
3.250
ꢁ1.909
In 1975, based on the concept of partial composition, Abrams
and Prausnitz proposed the UNIQUAC model [22]. The basic equa-
tion can be expressed as follows:
where x1 is the mole fraction of solute; T is the absolute tempera-
ture; a, b, c, and d are empirical parameters determined by solu-
bility fitting [17].
lng1 ¼ lngc1 þ lngR1
(13)
(14)
ꢂ
ꢃ
ꢂ
ꢃ
ꢂ
ꢃ
f1
x1
Z
2
q
r
r2
lngc1 ¼ ln
þ
q1ln
þ f2 l1
ꢁ
1l2
f1
3.3.
lh model
lngR1 ¼ ꢁ q1lnðq1
þ
q2t21Þ þ q2t21
In 1980, Buchowski et al. proposed the
l
h model. lh model has
ꢂ
ꢃ
the advantage of eliminating the need for other data in addition to
the melting point of a pure substance; therefore, this model was
widely used in the correlation of solideliquid phase equilibrium
data. The relationship between experimental solubility and tem-
perature can be expressed as Eq. (6):
t21
t12
þ
q2q1
ꢁ
(15)
(16)
(17)
q1
þ
q2t21
q2
þ
q1t12
rixi
r1x1 þ r2x2
fi ¼
ꢀ
ꢁ
ꢂ
ꢃ
ð1 ꢁ x1Þ
1
T
1
Tm
ln 1 þ
l
¼
l
h
ꢁ
(6)
x1
qixi
q1x1 þ q2x2
qi
¼
where x1 is the mole fraction of solute; T is the absolute tempera-
ture; Tm is the melting point according to the DSC curve; and h are
empirical parameters determined by solubility fitting [18].
l
ꢂ
ꢃ
D
uij
tij ¼ exp
ꢁ
(18)
RT
3.4. Wilson model
Z
2
li ¼ ðri ꢁ qiÞ ꢁ ðri ꢁ 1Þ
(19)
(20)
(21)
Wilson model [19] is based on the basis of a binary system, and
the basic equation can be expressed as follows:
Vwk
r1
¼
¼
ꢄ
ꢄ
ꢅ
ꢅ
15:17
v2
v1
l12
ꢁ
l11
L12
¼
¼
exp
exp
ꢁ
ꢁ
(7)
RT
Awk
2:5 ꢂ 109
q1
v1
v2
l21
ꢁ
l22
L21
(8)
RT
where ri and qi are the volume and surface area parameters of
component i, respectively. The volume and surface area parameter
of common solvents can be found in the manual [23]. Vwk and Awk
are the van der Waals volume and surface area, respectively. The
van der Waals volume and surface area of solute can be calculated
using the Materials Studio software; qi and fi are the average area
fraction and volume fraction of component i, respectively; Z is the
ꢀ
ꢁ
L12
x1 þ L12x2
L21
x2 þ L21x1
lng1 ¼ ꢁ lnðx1 þ L12x2Þ þ x2
ꢁ
(9)
where (l12
ꢁ
l11) and (l21
ꢁ
l22) are the binary cross-interaction
parameters and determined by solubility fitting; v1 and v2 are the
lattice coordination number, usually selected as 10;
nary cross-interaction parameters [24].
Duij is the bi-
mole volumes of solute and solvent, respectively [20].

J. Wang et al. / Journal of Molecular Liquids 296 (2019) 111784
7
4. Results and discussion
tetrahydrofuran, toluene > ether > n-hexane > ethanol > methanol,
following the rule “like dissolves like.”
4.1. Solubility and modeling
Figs. 7a and d show that the solubility in tetrahydrofuran is
significantly greater than that in other solvents. Therefore, tetra-
hydrofuran is the optimum solvent for compounds 1 and 4 for
participating in a homogeneous reaction. However, in the prepa-
ration of compound 4 shown in Fig. 4, toluene is suitable as the
optimum recrystallization solvent for compound 4. This is because
compound 4 is easily coordinated with ether and tetrahydrofuran,
affecting the yield of compound 4.
In Fig. 7b, the solubility of compound 2 in methanol and ethanol
is greater than that in tetrahydrofuran. However, it is difficult to
completely remove water from methanol and ethanol to ensure an
anhydrous and anaerobic environment. Therefore, tetrahydrofuran
is suitable as the optimum solvent for compound 2 for participating
in a homogeneous reaction.
In Fig. 7c, the solubility of nonpolar compound 3 in tetrahy-
drofuran and ether was greater than that in n-hexane. This is
probably because the solute is coordinated with ether and tetra-
hydrofuran, and tetrahydrofuran can be more easily coordinated
than ether, making it more soluble. The solubility in toluene is
greater than that in n-hexane, probably because the molecular
structure of compound 3 is more similar to toluene than n-hexane
due to the presence of a benzene ring in toluene.
The mole fraction solubilities x of compounds 1, 2, 3, and 4 in the
selected pure solvent between 268.15 and 313.15 K were calculated
using Eq. (4) and shown in Table 3. Table 2 shows that in the same
pure solvent such as toluene and ether, the solubilities of com-
pounds 1, 3, and 4 are greater than that of inorganic compound 2,
apparently because of the rule “like dissolves like.” However, the
solubility of inorganic compound 2 in tetrahydrofuran is not lower
and even larger than that of compound 4. This is probably because
tetrahydrofuran is easily coordinated with some compounds.
Tetrahydrofuran is a solvent with oxygen atoms, which can provide
lone pair electrons.
Tin in compound 2 and 4 is positively bivalent and has an empty
orbit that can accept lone pair electrons. The coordination between
compound 2 and tetrahydrofuran occur more easily due to less
steric hindrance of compound
2 [25,26], thus significantly
improving the solubility of compound 2. The experimental and
correlated results of compounds 1, 2, 3, and 4 are shown in Fig. 7,
respectively. The solid lines represent calculated values obtained
using the Apelblat model.
The polar order of all solvents is n-hexane > toluene > ether >
tetrahydrofuran > ethanol > methanol. Fig. 7 shows that the solu-
bility increased with increasing temperature; the solubility of
In another paper to be published by our group, the solubility of
another
b
-diketiminato
ligand
L0H
[L0 ¼ HC(CMeNAr)2,
compounds
furan > ether > toluene > n-hexane. The order for solubility of
compound is methanol > ethanol > tetrahydrofuran > ether >
1
and
4
followed the order: tetrahydro-
Ar ¼ 2,6-iPr2C6H3 ] was measured in several solvents [27]. In this
study, the solubility data of two
b-diketiminato ligands in four
2
solvents (toluene, tetrahydrofuran, methanol, and ethanol) were
compared and analyzed to determine the effect of molecular
structure on solubility.
toluene, and the order for solubility of nonpolar compound 3 is
Fig. 8 shows that the solubility of LH is basically greater than that
of L0H in all four selected solvents, probably because the size of
nonpolar substituents on the benzene ring of L0H are larger than
that of LH. Therefore, the polarity of LH is greater than L0H and is
closer to the polarity of selected four solvents.
LH has a higher solubility in the selected solvent, which is
largely favorable to increase the reaction efficiency of synthesis of
organometallics bearing b-diketiminato ligand LH. Meanwhile, the
solubility of ligand is not only related to the purity of organome-
tallics, but also significantly affects the size, morphology, and
crystallization mode of organometallics during crystallization
separation. Therefore, when a ligand is selected to synthesize or-
ganometallics, the effect of substituents of ligand on the solubility
should be considered, which can further affect homogeneous re-
action rate and recrystallization during the synthesis of
organometallics.
Table 3
Comparison of experimental mole fraction solubility (x) of two
gands: LH and L0H in selected solvents.
b
-diketiminato li-
solvent
toluene
T/K
100xexp of LH
100xexp of L’H
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
308.15
313.15
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
283.15
288.15
293.15
298.15
303.15
308.15
313.15
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
308.15
313.15
14.691
16.175
17.848
19.645
21.571
23.631
25.933
28.403
31.192
34.245
13.417
14.719
16.354
18.561
21.297
24.587
28.248
31.899
0.058
0.072
0.089
0.110
0.138
0.173
0.220
0.158
0.186
5.401
6.102
6.730
7.801
8.702
9.901
10.802
12.703
14.512
15.105
10.107
10.813
11.409
12.211
13.803
15.017
16.902
18.411
0.012
0.016
0.020
0.029
0.038
0.050
0.065
0.084
0.090
0.102
0.126
0.153
0.185
0.218
0.254
0.304
0.359
tetrahydrofuran
The deviation between measured data and calculated data was
evaluated by AAD. The basic equation can be expressed as Eq. (22):
methanol
ethanol
ꢈ
ꢈ
ꢈ
ꢈ
ꢈ
ꢈ
exp
i
N
X
x
ꢁ xci alc
100
N
AAD ¼
(22)
ꢈ
ꢈ
ꢈ
ꢈ
xei xp
i¼1
where N is the number of datapoints in different solvents; xei xp and
xci alc are the experimental solubility and calculated solubility,
respectively [16]. A model was retained when the values of AAD in
selected solvents were basically less than 3% as calculated by this
model. The results of compounds 1, 2, 3, and 4 are shown in
Tables 4e7, respectively.
0.220
0.258
0.315
0.369
0.476
0.595
0.738
0.964
The binary cross-interaction parameters in the Wilson model
(Dl12 and Dl21), NRTL model (
Dg12 and Dg21), and UNIQUAC model
(D
u12 and u21) were assumed to have a linear dependence on
D
temperature:

8
J. Wang et al. / Journal of Molecular Liquids 296 (2019) 111784
Fig. 7. Mole fraction solubility 102x in selected solvents: (a) compound 1, (b) compound 2, (c) compound 3, (d) compound 4.
selected solvents and compounds 1, 2, 3, and 4 are shown in Table 8.
kij
¼
aij
þ
bij
T
(23)
Based on Eq. (24) and the solubility parameter d2 of solvents ob-
tained from the literature [30], the solubility parameter of solute d1
can be determined. The results are also shown in Table 8.
To further improve the prediction accuracy of the simplified
ScatchardeHildebrand regular solution model, a binary interaction
parameter l12 was introduced into Eq. (24) to obtain a further
modified expression:
where k is any of the above interaction parameter. The parameters
and were fitted from the solubility data.
The model parameters A, B, and C of the Apelblat model, model
parameters a, b, c, and d of polynomial equation, model parameters
a
b
l
and h of lh model, model parameters a12, b12, a21, and b21 of
Wilson model, NRTL model, and UNIQUAC model in each solvent
were calculated based on solubility fitting, and the values of com-
pounds 1, 2, 3, and 4 are shown in Tables 4e7, respectively.
The Apelblat equation shows the best correlation results for
compound 1 with deviation less than 0.6%. The deviation of com-
pounds 2, 3, and 4 calculated by the Wilson model is less than 1%,
indicating that this model is suitable for the correlation of solubility
of compounds 2, 3, and 4 in selected solvents.
h
i
RTlng1 ¼ V1F22
ðd1
ꢁ
d2Þ2 þ 2l12d1d2
(25)
In this study, parameter l12 was correlated as a function of
temperature using
l12 ¼ a þ bðT = KÞ þ cðT=KÞ2
(26)
The parameters a, b, and c for each solvent obtained by regres-
sion from the experimental data are shown in Table 9. The AAD of
activity coefficients calculated using Eq. (25) is also shown in
Table 9. The AAD is defined as follows:
4.2. Correlation with ScatchardeHildebrand model
The ScatchardeHildebrand activity coefficient model for a reg-
ular solution is used to correlate the activity coefficients shown in
Table 2 [28,29]. Based on this model and further simplification, the
activity coefficient model used for the correlation in this study can
be expressed as follows:
ꢈ
ꢈ
ꢈ
ꢈ
ꢈ
ꢈ
exp
1
X
g
ꢁ
gc2alc
1
N
AAD ¼
(27)
ꢈ
ꢈ
ꢈ
ꢈ
ge1xp
i
where N represents the number of datapoints in different solvents;
“exp” represents the experimental values, and “calc” represents the
calculated values of activity coefficients.
RTlng1 ¼ V1F22ðd1
ꢁ
d2Þ2
(24)
where g1 is the activity coefficient of solute; V1 is the molar volume
of solute; d1 and d2 are the solubility parameters of solute and
solvent, respectively; R is the gas constant; T is the temperature; F2
is the volume fraction of solvent. The values of molar volume of
Based on Eq. (25) and the activity coefficients at infinite dilution
of solutes g∞1 are extrapolated to satisfy the condition
F2 / 1. The
results of g∞1 were correlated with temperature using the following
equation:

J. Wang et al. / Journal of Molecular Liquids 296 (2019) 111784
9
Fig. 8. Comparison of mole fraction solubility 102x of two
b-diketiminato ligands in four solvents: (a) toluene, (b) tetrahydrofuran, (c) methanol, (d) ethanol.
Table 4
Parameters and deviation of different models for compound 1 in pure solvents.
solvents
parameters
n-hexane
toluene
ether
tetrahydrofuran
modified Apelblat
A
B
C
AAD
a
b
c
d
AAD
a12
b12
a21
b21
AAD
a12
b12
a21
b21
AAD
2769.16
ꢁ1.34 ꢂ 105
ꢁ408.22
0.12
ꢁ19.23
ꢁ2055.84
4.05
ꢁ3.73
ꢁ73.02
1824.69
11.52
ꢁ2163.39
1.44
0.15
0.55
0.41
polynomial
Wilson
20.21
ꢁ2.57
ꢁ0.59
ꢁ5.66
ꢁ1.96 ꢂ 10ꢁ1
6.29 ꢂ 10ꢁ4
ꢁ6.73 ꢂ 10ꢁ7
0.07
3.08 ꢂ 10ꢁ2
ꢁ1.24 ꢂ 10ꢁ4
1.68 ꢂ 10ꢁ7
0.86
8.86 ꢂ 10ꢁ3
ꢁ4.36 ꢂ 10ꢁ5
7.13 ꢂ 10ꢁ8
0.16
6.43 ꢂ 10ꢁ2
ꢁ2.48 ꢂ 10ꢁ4
3.31 ꢂ 10ꢁ7
0.40
8.84 ꢂ 109
4.67 ꢂ 107
ꢁ14101.91
40.20
ꢁ5301.16
ꢁ10622.35
ꢁ8941.02
9.06
23.95
4.66
1953.11
1897.53
0.61
10318.56
5.91
0.16
ꢁ17811.41
73.07
0.71
1.53
NRTL
ꢁ28379.54
7.53 ꢂ 105
ꢁ2194.94
ꢁ6168.11
23.47
ꢁ15384.09
ꢁ5987.99
71.37
84.18
35.39
1.17 ꢂ 105
ꢁ298.63
0.15
ꢁ10194.73
23.42
0.14
ꢁ6254.74
ꢁ0.87
0.51
0.54
(29) are listed in Table 10. These results are useful for the estimation
of heat of dissolution of compounds in the selected solvents.
ꢉ
lng∞1 ¼ a’ þ b’ ðT = KÞ
(28)
According to the GibbseHelmholtz equation, the value for par-
tial molar excess enthalpy at infinite dilution HE1,∞ can be directly
obtained from the slope of a straight line derived from Eq. (28)
4.3. Mixing properties calculation
HE1;∞
R
v ln g∞1
vð1=TÞ
According to the Lewis Randall rule, where the standard state is
the actual state of pure component, the mixing properties of a so-
lution can be determined by adding excess properties. The ideal
thermodynamic properties can be expressed as follows [31]:
¼
(29)
The coefficients a’ and b’ and the values of HE1,∞ derived from Eq.

10
J. Wang et al. / Journal of Molecular Liquids 296 (2019) 111784
Table 5
Parameters and deviation of different models for compound 2 in pure solvents.
solvents
parameters
toluene
ether
tetrahydrofuran
methanol
ethanol
modified Apelblat
A
B
C
AAD
a
b
c
d
AAD
a12
b12
a21
b21
AAD
ꢁ771.43
31132.46
115.99
ꢁ725.50
29322.29
109.28
ꢁ25.58
ꢁ50.03
631.98
8.28
590.77
ꢁ731.76
4.65
ꢁ27226.45
ꢁ87.81
0.45
2.32
0.88
0.58
0.43
polynomial
Wilson
ꢁ1.23
ꢁ3.09
ꢁ12.96
ꢁ23.01
2.48 ꢂ 10ꢁ1
ꢁ9.03 ꢂ 10ꢁ4
1.13 ꢂ 10ꢁ6
0.18
ꢁ1304.96
ꢁ34.50
1.41 ꢂ 105
ꢁ444.94
0.91
36.62
1.32 ꢂ 10ꢁ2
ꢁ4.73 ꢂ 10ꢁ5
5.66 ꢂ 10ꢁ8
2.21
3.42 ꢂ 10ꢁ2
ꢁ1.26 ꢂ 10ꢁ4
1.56 ꢂ 10ꢁ7
1.14
1.39 ꢂ 10ꢁ1
ꢁ5.07 ꢂ 10ꢁ4
6.30 ꢂ 10ꢁ7
0.35
ꢁ4.27 ꢂ 10ꢁ1
1.62 ꢂ 10ꢁ3
ꢁ2.01 ꢂ 10ꢁ6
0.22
7586.27
34.25
1.03 ꢂ 106
ꢁ3345.56
ꢁ4643.97
14.45
ꢁ2503.19
ꢁ1933.72
ꢁ30.27
ꢁ74.77
39.60
ꢁ14.84
ꢁ5129.24
1.30 ꢂ 105
ꢁ398.06
0.14
0.10
0.27
0.14
0.67
Table 6
Parameters and deviation of different models for compound 3 in pure solvents.
solvents
parameters
n-hexane
toluene
ether
tetrahydrofuran
methanol
ethanol
modified Apelblat
A
B
C
AAD
a
b
c
d
AAD
l
ꢁ4.78
ꢁ56.45
1048.13
9.05
383.57
ꢁ19150.37
ꢁ56.29
0.42
ꢁ193.59
6463.58
29.95
0.94
25.35
ꢁ83.79
59.14
13.48
ꢁ460.74
16929.29
69.96
ꢁ3035.99
2.29
0.00
0.16
2.67
1.30
polynomial
ꢁ16.18
1.85 ꢂ 10ꢁ1
ꢁ7.12 ꢂ 10ꢁ4
9.22 ꢂ 10ꢁ7
0.15
1.14
3330.44
0.54
4759.08
ꢁ25.73
918.29
12.21
0.03
1942.89
2.56
ꢁ6.23
16.40
ꢁ0.35
ꢁ1.82
6.91 ꢂ 10ꢁ2
ꢁ2.60 ꢂ 10ꢁ4
3.41 ꢂ 10ꢁ7
0.09
ꢁ1.73 ꢂ 10ꢁ1
5.95 ꢂ 10ꢁ4
ꢁ6.55 ꢂ 10ꢁ7
0.25
ꢁ2.49 ꢂ 10ꢁ1
8.02 ꢂ 10ꢁ4
ꢁ8.30 ꢂ 10ꢁ7
0.35
3.84 ꢂ 10ꢁ3
ꢁ1.40 ꢂ 10ꢁ5
1.71 ꢂ 10ꢁ8
1.24
1.98 ꢂ 10ꢁ2
ꢁ7.18 ꢂ 10ꢁ5
8.72 ꢂ 10ꢁ8
1.30
lh
1.61 ꢂ 10ꢁ1
4448.59
0.69
1.36
2256.12
3.59
ꢁ1992.77
170.46
ꢁ898.36
4.15
7.20 ꢂ 10ꢁ1
2735.95
2.06
5.00 ꢂ 10ꢁ3
6.39 ꢂ 105
0.94
2.00 ꢂ 10ꢁ2
1.53 ꢂ 105
4.83
h
AAD
a12
b12
a21
b21
AAD
a12
b12
a21
b21
AAD
Wilson
NRTL
ꢁ12184.03
324.25
2794.61
7.71
ꢁ3375.89
6004.66
0.78
ꢁ196.44
7607.07
4802.64
27.83
5678.75
0.55
19.76
ꢁ25.78
ꢁ53082.60
219.76
12674.74
ꢁ9.99
ꢁ10319.32
51.02
0.08
0.85
0.44
0.77
ꢁ5339.57
ꢁ17781.78
ꢁ12704.54
ꢁ10983.74
32.61
49.79
29.72
23.64
4409.37
ꢁ17.83
0.02
ꢁ9830.58
21.33
0.08
138.56
52.16
0.16
ꢁ4655.76
58.13
0.21
25063.44
ꢁ27.64
0.80
1.91
Table 7
Parameters and deviation of different models for compound 4 in pure solvents.
solvents
parameters
n-hexane
toluene
ether
343.66
tetrahydrofuran
modified Apelblat
A
B
C
AAD
a
b
c
d
AAD
l
ꢁ13.30
17.39
ꢁ273.24
8591.08
42.38
ꢁ2218.84
ꢁ3326.11
ꢁ1.66
0.17
ꢁ17561.36
2.56
ꢁ50.53
0.07
0.60
3.69
polynomial
ꢁ1.06 ꢂ 10ꢁ1
1.23 ꢂ 10ꢁ3
ꢁ4.88 ꢂ 10ꢁ6
6.54 ꢂ 10ꢁ9
0.07
ꢁ7.30 ꢂ 10ꢁ1
ꢁ9.61 ꢂ 10ꢁ1
1.08 ꢂ 10ꢁ2
ꢁ4.29 ꢂ 10ꢁ5
6.04 ꢂ 10ꢁ8
0.21
ꢁ25.46
2.76 ꢂ 10ꢁ1
ꢁ1.00 ꢂ 10ꢁ3
1.21 ꢂ 10ꢁ6
1.44
7.11
594.24
7.70
9.75 ꢂ 10ꢁ3
ꢁ4.36 ꢂ 10ꢁ5
6.57 ꢂ 10ꢁ8
0.13
lh
5.23 ꢂ 10ꢁ2
54886.67
0.09
0.99
2863.86
0.19
3986.06
ꢁ10.57
ꢁ2138.95
7.64
1.62
1952.56
2.90
h
AAD
a12
b12
a21
b21
AAD
a12
b12
a21
b21
AAD
a12
b12
a21
b21
AAD
Wilson
NRTL
ꢁ3399.31
3.01 ꢂ 109
1.17 ꢂ 107
ꢁ3611.29
9.73
ꢁ37689.89
14.84
137.88
1.21 ꢂ 105
ꢁ330.65
0.02
7715.18
ꢁ26.05
0.37
32370.69
ꢁ116.30
ꢁ36840.34
125.73
0.12
0.58
4.76 ꢂ 1010
3.86 ꢂ 107
ꢁ3471.50
31.72
ꢁ3098.88
1.65 ꢂ 105
ꢁ506.75
18686.59
ꢁ77.30
ꢁ0.29
3414.87
ꢁ0.90
0.03
0.13
0.21
0.96
UNIQUAC
ꢁ229.71
2841.37
ꢁ25.80
3478.34
ꢁ71191.44
ꢁ36.69
132.33
0.22
2871.89
ꢁ58731.87
ꢁ37.67
8541.46
ꢁ1.75 ꢂ 105
ꢁ56.62
445.57
ꢁ136.83
0.02
66.21
0.11
1.60

J. Wang et al. / Journal of Molecular Liquids 296 (2019) 111784
11
Table 8
Table 11
Solubility parameter and liquid molar volume of selected solvents and compounds 1,
2, 3, and 4 in pure solvents.
Calculated values of compound 1 in selected solvents for DmixG, DmixH, and DmixS.
T/K
DmixG (J$molꢁ1
)
DmixH (J$molꢁ1
)
DmixS (J$molꢁ1$Kꢁ1
)
1/2
substance
di/(J$cmꢁ3
)
106Vi/m3$molꢁ1
n-hexane
303.15
308.15
313.15
318.15
323.15
toluene
273.15
278.15
283.15
288.15
293.15
298.15
303.15
308.15
313.15
ether
n-hexane
toluene
ether
tetrahydrofuran
methanol
ethanol
dimethyltin dichloride
stannous chloride
14.90
18.35
14.83
19.13
29.52
26.42
21.34
24.20
20.46
18.16
131.59
106.60
103.90
81.94
40.70
58.52
157.26
48.62
385.69
356.37
ꢁ22.682
ꢁ34.783
ꢁ47.008
ꢁ56.943
ꢁ62.230
ꢁ17.514
ꢁ23.721
ꢁ27.970
ꢁ29.120
ꢁ26.821
0.017
0.036
0.061
0.087
0.110
ꢁ193.750
ꢁ229.603
ꢁ273.853
ꢁ317.339
ꢁ366.748
ꢁ431.599
ꢁ492.489
ꢁ560.000
ꢁ632.967
ꢁ49.899
ꢁ60.096
ꢁ73.185
ꢁ86.145
ꢁ101.324
ꢁ122.481
ꢁ142.581
ꢁ165.749
ꢁ191.801
0.527
0.609
0.709
0.802
0.905
1.037
1.154
1.279
1.409
b
-diketimine
LSnCl
Table 9
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
ꢁ282.219
ꢁ325.124
ꢁ370.975
ꢁ421.154
ꢁ474.079
ꢁ532.489
ꢁ593.909
ꢁ654.461
ꢁ102.168
ꢁ118.998
ꢁ136.872
ꢁ156.506
ꢁ177.217
ꢁ200.417
ꢁ224.990
ꢁ248.982
0.671
0.755
0.842
0.935
1.030
1.133
1.237
1.338
Parameters of Eq. (27) and AAD of measured activity coefficients with the calculated
results obtained from Eqs. (25) and (26) for solutes in selected solvents.
solvent
a
b
c
AAD%
dimethyltin dichloride
n-hexane
5.52753
ꢁ3.49 ꢂ 10ꢁ2
ꢁ1.45 ꢂ 10ꢁ4
ꢁ2.55 ꢂ 10ꢁ4
8.71 ꢂ 10ꢁ3
5.52 ꢂ 10ꢁ5
6.01 ꢂ 10ꢁ7
1.12 ꢂ 10ꢁ6
ꢁ1.59 ꢂ 10ꢁ5
0.20
0.60
0.20
1.57
toluene
ether
tetrahydrofuran
stannous chloride
toluene
ꢁ0.01470
ꢁ0.09119
ꢁ1.27821
tetrahydrofuran
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
308.15
313.15
ꢁ1649.969
ꢁ877.510
2.881
3.037
3.177
3.323
3.459
3.586
3.709
3.802
3.875
3.914
ꢁ1773.640
ꢁ1886.165
ꢁ2013.566
ꢁ2139.421
ꢁ2267.812
ꢁ2420.072
ꢁ2542.483
ꢁ2654.690
ꢁ2798.366
ꢁ944.054
ꢁ2.90251
ꢁ3.88049
ꢁ1.66163
2.00 ꢂ 10ꢁ2
2.57 ꢂ 10ꢁ2
1.14 ꢂ 10ꢁ2
ꢁ3.36 ꢂ 10ꢁ5
ꢁ4.37 ꢂ 10ꢁ5
ꢁ2.19 ꢂ 10ꢁ5
1.80
0.80
1.71
ꢁ1002.514
ꢁ1072.713
ꢁ1142.833
ꢁ1216.690
ꢁ1314.264
ꢁ1390.053
ꢁ1460.683
ꢁ1572.766
ether
tetrahydrofuran
b
-diketimine
n-hexane
toluene
ether
tetrahydrofuran
methanol
ethanol
LSnCl
n-hexane
toluene
ether
tetrahydrofuran
0.02977
0.31398
0.18426
ꢁ1.40948
ꢁ0.09023
ꢁ0.12650
ꢁ5.28 ꢂ 10ꢁ4
ꢁ2.51 ꢂ 10ꢁ3
ꢁ1.38 ꢂ 10ꢁ3
1.01 ꢂ 10ꢁ2
2.77 ꢂ 10ꢁ4
7.08 ꢂ 10ꢁ4
9.42 ꢂ 10ꢁ7
4.69 ꢂ 10ꢁ6
1.82 ꢂ 10ꢁ6
ꢁ1.83 ꢂ 10ꢁ5
ꢁ3.61 ꢂ 10ꢁ7
ꢁ1.05 ꢂ 10ꢁ6
0.04
0.44
0.64
0.48
0.40
0.96
ꢁ0.03662
ꢁ0.05867
0.33752
ꢁ1.13623
1.49 ꢂ 10ꢁ4
3.64 ꢂ 10ꢁ4
ꢁ2.50 ꢂ 10ꢁ3
8.08 ꢂ 10ꢁ3
1.76 ꢂ 10ꢁ8
ꢁ6.69 ꢂ 10ꢁ7
4.22 ꢂ 10ꢁ6
ꢁ1.45 ꢂ 10ꢁ5
0.03
0.12
0.54
1.66
DmixM ¼ ME
þ
DMid
(30)
For
M ¼ G; H; and S
where ME is the excess thermodynamic property;
(31)
DGid,
D
Sid, and
DHid are ideal thermodynamic properties.
Table 10
D
D
D
Gid ¼ RTðx1lnx1 þ x2lnx2Þ
Sid ¼ ꢁ Rðx1lnx1 þ x2lnx2Þ
Hid ¼ 0
(32)
(33)
(34)
Coefficients of Eq. (28) and values of HE,∞ 1 derived from Eq. (29) for solutes in
selected solvents.
solvent
a’
b’/K
HE,∞ 1/kJ$molꢁ1
dimethyltin dichloride
n-hexane
toluene
ꢁ4.19525
3.07041
4.60064
ꢁ7.89855
2199.46
ꢁ810.69
ꢁ1380.40
958.32
18.29
ꢁ6.74
ꢁ11.48
7.97
ether
Here, x1 and x2 are the mole fraction of solute and solvent,
tetrahydrofuran
stannous chloride
toluene
ether
tetrahydrofuran
respectively. Based on the Wilson model, the excess mixing ther-
modynamic properties are shown in Eqs. (35)e(37) [32].
2.82683
3.44973
ꢁ7.09279
ꢁ246.36
ꢁ878.85
1118.69
ꢁ2.05
ꢁ7.31
9.30
GE ¼ ꢁ RT½x1lnðx1 þ x2L12Þ þ x2lnðx2 þ x1L21Þꢃ
(35)
b
-diketimine
ꢀ
ꢁ
ꢂ
ꢃ
n-hexane
toluene
ether
tetrahydrofuran
methanol
ethanol
LSnCl
n-hexane
toluene
ether
tetrahydrofuran
0.27266
7.25310
ꢁ9.61713
ꢁ12.23261
3.77053
4.80808
110.72
0.92
ðvGE=TÞ
vT
Dl12L12
x1 þ L12x2
Dl21L21
x2 þ L21x1
HE ¼ ꢁ T2 ꢁ RT
¼ x1x2
þ
ꢁ2556.87
2494.24
2771.68
449.79
ꢁ21.26
20.74
23.04
3.74
(36)
ꢁ254.72
ꢁ2.12
HE ꢁ GE
SE
¼
(37)
3.69624
ꢁ427.66
ꢁ121.99
485.04
ꢁ3.56
ꢁ1.01
4.03
T
ꢁ0.50524
ꢁ2.62174
ꢁ9.99732
DmixG, DmixH, and DmixS were calculated from the model pa-
2466.57
20.51
rameters, and the experimental solubility of Wilson model is
shown in Tables 11e14. The mixing Gibbs energy (DmixG) of a

12
J. Wang et al. / Journal of Molecular Liquids 296 (2019) 111784
Table 12
Table 13
Calculated values of compound 2 in selected solvents for DmixG, DmixH, and DmixS.
Calculated values of compound 3 in selected solvents for DmixG, DmixH, and DmixS.
T/K
DmixG (J$molꢁ1
)
DmixH (J$molꢁ1
)
DmixS (J$molꢁ1$Kꢁ1
)
T/K
DmixG (J$molꢁ1
)
DmixH (J$molꢁ1
)
DmixS (J$molꢁ1$Kꢁ1
)
toluene
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
308.15
313.15
ether
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
n-hexane
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
308.15
313.15
toluene
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
308.15
313.15
ether
ꢁ13.683
ꢁ14.542
ꢁ15.155
ꢁ16.805
ꢁ18.185
ꢁ21.079
ꢁ23.743
ꢁ27.790
ꢁ34.556
ꢁ44.523
ꢁ19.074
ꢁ19.508
ꢁ19.422
ꢁ21.128
ꢁ22.242
ꢁ25.921
ꢁ29.059
ꢁ34.516
ꢁ44.734
ꢁ60.703
ꢁ0.020
ꢁ0.018
ꢁ0.015
ꢁ0.015
ꢁ0.014
ꢁ0.017
ꢁ0.018
ꢁ0.022
ꢁ0.033
ꢁ0.052
ꢁ307.265
ꢁ379.350
ꢁ463.627
ꢁ560.876
ꢁ671.797
ꢁ796.637
ꢁ935.001
ꢁ1085.822
ꢁ1246.688
ꢁ1413.632
ꢁ115.296
ꢁ152.944
ꢁ200.210
ꢁ258.573
ꢁ329.546
ꢁ414.373
ꢁ513.767
ꢁ627.753
ꢁ754.937
ꢁ892.173
0.716
0.829
0.947
1.068
1.188
1.304
1.413
1.511
1.596
1.665
ꢁ8.947
ꢁ3.085
ꢁ2.763
ꢁ2.508
ꢁ2.358
ꢁ2.238
ꢁ2.086
ꢁ1.862
28.998
0.022
0.023
0.024
0.027
0.031
0.035
0.042
0.170
ꢁ1210.484
ꢁ1283.078
ꢁ1358.268
ꢁ1431.163
ꢁ1500.827
ꢁ1566.241
ꢁ1629.763
ꢁ1686.756
ꢁ1739.251
ꢁ1782.740
ꢁ871.109
ꢁ926.261
ꢁ984.147
ꢁ1039.682
ꢁ1091.653
ꢁ1138.636
ꢁ1183.180
ꢁ1219.526
ꢁ1249.971
ꢁ1268.497
1.266
1.306
1.345
1.383
1.420
1.459
1.498
1.541
1.588
1.642
ꢁ9.006
ꢁ9.285
ꢁ10.045
ꢁ11.159
ꢁ12.454
ꢁ14.275
ꢁ22.399
tetrahydrofuran
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
308.15
313.15
methanol
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
308.15
313.15
ethanol
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
308.15
313.15
ꢁ1278.688
ꢁ689.940
ꢁ807.821
ꢁ939.486
ꢁ1083.761
ꢁ1239.450
ꢁ1409.148
ꢁ1588.699
ꢁ1788.315
ꢁ1982.394
ꢁ2232.595
2.196
2.394
2.590
2.778
2.957
3.133
3.312
3.520
3.770
4.127
ꢁ1461.749
ꢁ1659.789
ꢁ1870.299
ꢁ2091.496
ꢁ2327.667
ꢁ2576.208
ꢁ2855.291
ꢁ3144.253
ꢁ3524.840
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
ꢁ499.712
ꢁ644.442
ꢁ804.488
ꢁ969.024
ꢁ1131.803
ꢁ1284.287
ꢁ1428.473
ꢁ1567.068
30.965
37.613
44.040
49.653
54.231
57.609
59.993
61.520
1.979
2.497
3.051
3.598
4.116
4.578
4.992
5.372
tetrahydrofuran
ꢁ1162.935
ꢁ3259.249
ꢁ3674.390
ꢁ4043.766
ꢁ4445.381
ꢁ4862.105
ꢁ5311.566
ꢁ5795.620
ꢁ6341.849
ꢁ6994.991
ꢁ7808.233
ꢁ2746.831
ꢁ3188.791
ꢁ3595.646
ꢁ4054.951
ꢁ4544.155
ꢁ5075.032
ꢁ5622.648
ꢁ6183.737
ꢁ6834.842
ꢁ7883.958
1.911
1.778
1.611
1.379
1.103
0.807
0.580
0.522
0.520
ꢁ0.242
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
methanol
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
308.15
313.15
ethanol
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
308.15
313.15
64.326
4.577
4.975
5.410
5.895
6.379
6.824
7.185
7.430
ꢁ1229.026
ꢁ1315.435
ꢁ1433.038
ꢁ1576.884
ꢁ1743.475
ꢁ1919.533
ꢁ2088.052
129.981
189.367
236.246
261.087
256.956
222.662
164.312
ꢁ2.439
ꢁ2.956
ꢁ3.550
ꢁ4.237
ꢁ5.042
ꢁ5.959
ꢁ6.989
ꢁ8.227
ꢁ9.664
ꢁ11.390
1.405
1.773
2.215
2.754
3.422
4.225
5.180
6.405
7.926
9.903
0.014
0.017
0.021
0.025
0.029
0.035
0.041
0.048
0.057
0.068
ꢁ2395.589
ꢁ2982.004
ꢁ3546.486
ꢁ4062.963
ꢁ4521.045
ꢁ4902.982
ꢁ5217.876
ꢁ5446.520
ꢁ5592.240
ꢁ5683.218
ꢁ1703.669
ꢁ2229.423
ꢁ2773.090
ꢁ3305.543
ꢁ3808.791
ꢁ4251.603
ꢁ4632.258
ꢁ4910.837
ꢁ5077.807
ꢁ5166.538
2.580
2.755
2.781
2.675
2.472
2.222
1.964
1.767
1.669
1.650
ꢁ12.655
ꢁ14.290
ꢁ16.138
ꢁ18.058
ꢁ20.843
ꢁ23.347
ꢁ27.841
ꢁ32.445
ꢁ37.503
ꢁ44.712
16.060
18.742
21.841
25.131
30.050
34.576
43.093
52.156
62.468
77.802
0.107
0.121
0.137
0.153
0.177
0.198
0.238
0.279
0.324
0.391
solution can be used to determine the dissolution capacity of a
solute [33]. The values of DmixG for compounds 1, 2, 3, and 4 in all
selected solvents are negative and decreased with increasing
temperature to indicate the dissolution of compounds 1, 2, 3, and 4
in different pure solvents. This is a spontaneous and favorable
process.
solvent, which is the greatest advantage for organotin compounds
to make them suitable for use in homogeneous reaction. Tin in
compound 2 and 4 is positively bivalent and has an empty orbit that
can accept lone pair electrons from ether and tetrahydrofuran, thus
5. Conclusion
The solubilities of compounds 1, 2, 3, and 4 in selected solvents
were measured using a static analytic method from 268.15 K to
313.15 K under a purified nitrogen atmosphere. The solubility
increased with increasing temperature. Tetrahydrofuran is the op-
timum solvent for compounds 1, 2, and 4 for participating in a
homogeneous reaction. The solubilities of compounds 1, 3, and 4
are greater than that of inorganic compound 2 in the same pure
improving the solubility. The solubility data of two b-diketiminato
ligands showed that the solubility of LH was greater than that of L0H
in all four selected solvents, probably because the size of nonpolar
substituents on the benzene ring of LH is less than that of L0H. The
effect of coordination and substituents on the solubility should be

J. Wang et al. / Journal of Molecular Liquids 296 (2019) 111784
13
Table 14
Calculated values of compound 4 in selected solvents for DmixG, DmixH, and DmixS.
Acknowledgments
We gratefully acknowledge financial support of this work by the
National Natural Science Foundation of China (21671018,
21872005).
T/K
DmixG (J$molꢁ1
)
DmixH (J$molꢁ1
)
DmixS (J$molꢁ1$Kꢁ1
)
n-hexane
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
308.15
313.15
toluene
268.15
273.15
278.15
283.15
288.15
293.15
298.15
303.15
308.15
313.15
ether
ꢁ9.442
0.157
0.246
0.366
0.520
0.719
0.970
1.283
1.670
2.144
2.721
0.036
0.042
0.050
0.058
0.067
0.078
0.089
0.102
0.116
0.131
ꢁ11.320
ꢁ13.474
ꢁ15.924
ꢁ18.696
ꢁ21.813
ꢁ25.303
ꢁ29.197
ꢁ33.535
ꢁ38.328
Appendix A. Supplementary data
Supplementary data to this article can be found online at
https://doi.org/10.1016/j.molliq.2019.111784.
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ꢁ91.943
0.352
0.399
0.448
0.500
0.553
0.607
0.661
0.712
0.759
0.803
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No conflict of interest exits in the submission of this manuscript,
and manuscript is approved by all authors for publication. I would
like to declare on behalf of my co-authors that the work described
was original research that has not been published previously, and
not under consideration for publication elsewhere. All the authors
listed have approved the manuscript that is enclosed.

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