Reconnaissance of the reactions of carbamodithiolate salts with dialkyltin dichloride

Article abstract of DOI:10.1016/j.molstruc.2020.129541

Reactions of carbamodithiolate salts viz., c-C₃H₅NH₃⁺(L¹)^? and c-C₆H₁₁NH₃⁺(L²)^? (L¹ = cyclopropylcarbamodithioat

Full text of DOI:10.1016/j.molstruc.2020.129541

Journal Pre-proof
Reconnaissance of the reactions of carbamodithiolate salts with
dialkyltin dichloride
Tushar S. Basu Baul , Maheswara Rao Addepalli , Andrew Duthie ,
M. F a´ tima C. Guedes da Silva
PII:
S0022-2860(20)31856-1
DOI:
Reference:
https://doi.org/10.1016/j.molstruc.2020.129541
MOLSTR 129541
To appear in:
Journal of Molecular Structure
Received date:
Revised date:
Accepted date:
15 September 2020
27 October 2020
28 October 2020
Please cite this article as: Tushar S. Basu Baul , Maheswara Rao Addepalli , Andrew Duthie ,
M. F a´ tima C. Guedes da Silva ,
Reconnaissance of the reactions of carbamodithi-
olate salts with dialkyltin dichloride, Journal of Molecular Structure (2020), doi:
https://doi.org/10.1016/j.molstruc.2020.129541
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Highlights



Reactions of carbamodithiolate salts with R SnCl have been investigated.
2
2
1
13
119
Four new complexes were characterized by IR, H, C, and Sn NMR spectroscopy.
Complexes 1-4 and carbamodithiolate salts have been characterized by single crystal X-ray
crystallography.


X-ray analysis revealed two types of complexes with distorted square pyramid and skewed
trapezoidal bipyramid geometry around tin atom.
The 3D Hirshfeld surfaces have been mapped to study the intermolecular interactions.
1

Reconnaissance of the reactions of carbamodithiolate salts with dialkyltin
dichloride
a,*
a
b
Tushar S. Basu Baul, Maheswara Rao Addepalli, Andrew Duthie, M. Fátima C. Guedes
c,*
da Silva
a
Centre for Advanced Studies in Chemistry, North-Eastern Hill University, NEHU Permanent
Campus, Umshing, Shillong 793 022, India
b
School of Life & Environmental Science, Deakin University, Geelong, Victoria 3217, Australia
c
Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, Universidade de Lisboa,
Av. Rovisco Pais, 1049-001 Lisboa, Portugal
2

ABSTRACT
Reactions of carbamodithiolate salts viz., c-C H NH (L ) and c-C H NH (L ) (L
+
3
1 -
+
3
2 -
1
=
3
6
6
12
2
cyclopropylcarbamodithioate, L = cyclohexylcarbamodithioate) with R SnCl (R = Me or n-Bu)
2
2
were investigated in dichloromethane for the first time. A series of four diorganotin(IV)
1
1
2
complexes of composition [Me Sn(L )Cl] (1), [Me Sn(L ) ] (2), [Me Sn(L ) ] (3) and [n-
2
2
2
2
2
2
Bu Sn(L ) ] (4) were isolated and characterized by spectroscopic methods. The structures of the
2
2
two carbamodithiolate salts and the diorganotin(IV) compounds 1-4 were accomplished by X-ray
crystallographic analysis revealing distorted square pyramid geometry for 1, but skewed
trapezoidal bipyramids for 2-4. Influence of the carbamodithiolate moiety on the hydrogen-bond
interactions and non-covalent contacts, as well as on the packing of the structures, is discussed.
The 3D Hirshfeld surfaces were mapped and used to study the intermolecular interactions.
Keywords: diorganotin/ carbamodithiolate ligands/ spectroscopy/ crystal structure/ non-covalent
contacts/ Hirshfeld surfaces
_
*
_________________
Corresponding authors.
E-mail addresses: basubaul@nehu.ac.in, basubaulchem@gmail.com (T. S. Basu Baul),
fatima.guedes@tecnico.ulisboa.pt (M. Fátima C. Guedes da Silva).
3

1
. Introduction
Dithiocarbamic acids are excellent nucleophiles to a broad range of electrophiles,
especially when derived from primary amines [1]. Although they are labile, their metal
complexes and esters are stable and have found extensive applications e.g. as fungicides and
pesticides [2], in vulcanization during rubber manufacturing [3], in polymerization reactions [4],
as organic intermediates [5], in medicinal chemistry [6] and for the synthesis of metal sulfide
nanoparticles [7]. Over the last few years significant attention has been paid to dithiocarbamate
organotin chemistry and consequently organotin(IV) dithiocarbamates have reached a distinct
¯
2
pinnacle [8-10]. The strong Lewis acidity of tin, the presence of the anionic CS moiety in the
dithiocarbamate ligand and the ease of synthesizing such complexes, led to the development of
compounds of the type [R Sn(S CNR ) ] (n = 1 – 4) with a reasonable degree of predictability
4
-n
2
2 n
of the solid state structures for a given combination of R and R’ [8]. Accordingly, a large number
of such complexes were explored for the preparation of tin sulfide/ tin sulfide nanomaterials
[
11,12], photoluminescent materials [13], selective anion and ion receptors [14-16], fascinating
architectures [15-19] and in biology [20-25], to mention some.
Although organotin(IV) compounds containing aromatic or aliphatic substituents at the
dithiocarbamate fragment are abundant, those featuring a primary amine such as
cyclopropylcarbamodithioate and cyclohexylcarbamodithioate are scarce except for a report by
Jabbar et al. [26], wherein cyclohexylcarbamodithioic acid was isolated from a reaction of
cyclohexylamine with carbon disulfide in ethanol. By following identical methodology we
succeeded in the isolation and characterization of the carbamodithiolate salts viz., c-
+
1 -
+
2 -
1
2
C H NH (L )
and c-C H NH (L )
(L
=
cyclopropylcarbamodithioate,
L
=
3
6
3
6
12
3
cyclohexylcarbamodithioate) and explored their synthetic potential towards diorganotin(IV)
4

dichloride. Report on the reactions of primary amine derived carbamodithioate salts with
diorganotin(IV) dihalide are rare [27], although such reactions are known for secondary amines
[
28]. Additionally, it is known that the dithiocarbamates obtained from secondary amines are
more stable than the products obtained from primary amines [29]. Here we report the
1
1
preparations and isolation of diorganotin(IV) compounds viz., [Me Sn(L )Cl] (1), [Me Sn(L ) ]
2
2
2
2
2
(
2), [Me Sn(L ) ] (3) and [n-Bu Sn(L ) ] (4) which were characterized by means of IR and NMR
2 2 2 2
+
1 -
+
2 -
spectroscopy. The molecular structures of c-C H NH (L ) and c-C H NH (L ) and 1-4 have
3
6
3
6
12
3
been determined by single crystal X-ray crystallography (SCXRD).
2
. Experimental
2
.1. Materials and physical measurements
Dimethyltin dichloride (Sigma Aldrich), di(n-butyl)tin dichloride (Stream chemicals),
cyclopropylamine, cyclohexylamine, carbon disulfide (Spectrochem), and ethanol (Merck) were
used as received. The solvents used in the reactions were of AR grade and dried using standard
procedures. Melting points were measured using a Büchi M-560 melting point apparatus and are
uncorrected. Elemental analyses were performed using a Perkin Elmer 2400 series II instrument.
–
1
IR spectra in the range 4000-400 cm were obtained on a Bruker Alpha-II FT-IR
1
13
spectrophotometer with samples investigated as KBr discs (Figs. S1-S6). The H and C spectra
of compounds (carbamodithiolate salts and diorganotin(IV) compounds 1-4, Figs. S7-S18) were
recorded on a Bruker AMX 400 spectrometer and measured at 400.13 and 100.62 MHz,
1
19
respectively. Solution Sn NMR spectra of compounds 1-4 were measured on a Jeol Zeta ECZ
1
13
119
4
00R spectrometer at 149.08 MHz (Fig. S19). H, C and Sn chemical shifts were referenced
to SiMe (δ 0.00 ppm), CDCl (δ 77.00 ppm), and Me Sn (δ 0.00 ppm), respectively.
4
3
4
5

2
.2. Preparation of carbamodithiolate salts
Although reports on cyclopropanaminium cyclopropylcarbamodithioate [30] and
cyclohexanaminium cyclohexylcarbamodithioate [31-33] are available in the literature, either the
synthetic procedure or the characterization data is inadequate. Consequently, a general method
has been developed which is described below.
+
1 -
2
.2.1. Synthesis of cyclopropanaminium cyclopropylcarbamodithioate, c-C H NH (L )
3 6 3
Carbon disulfide (0.41 mL, 0.54 g, 7.15 mmol) was added dropwise to a stirred absolute
ethanol solution (5 mL) of cyclopropylamine (1.00 mL, 0.82 g, 14.36 mmol) in a round bottom
flask held at around 0 °C. Even though a pale-yellow precipitate was instantly formed the
reaction mixture was allowed to gradually reach room temperature and the stirring was
maintained for 4 h. The solid was then filtered, washed with small amount of ethanol and dried
in vacuo. Pale-yellow crystals suitable for X-ray analysis were obtained upon slow evaporation
of a methanolic solution of the product. Yield 1.1 g (84%). M.p.: 112-113 °C (109-111 °C [30]).
Anal. found: C, 44.28; H, 7.62; N, 14.80. Calcd. for C H N S : C, 44.17; H, 7.41; N, 14.72%.
7
14
2 2
1
H NMR (CDCl +DMSO-d ) δ (ppm): 7.76 (s, 1H, NH), 6.03 (bs, 3H, 3NH), 3.15-3.14 (m, 1H,
3
6
H
13
CH), 2.58-2.54 (m, 1H, CH), 0.81-0.50 (m, 8H, 4CH ). C NMR (CDCl +DMSO-d ) δ (ppm):
2
3
6
c
-
1
2
3
14.37 (C=S), 29.25 (CH), 22.74 (CH), 6.65 (CH ), 4.19 (CH ). IR absorption (cm ): 3222 (w),
2 2
180 (s), 3086 (w), 2994 (m), 1645 (w), 1557 (s), 1512 (m), 1453 (w), 1403 (w), 1339 (m), 1274
(
m), 1221 (w), 1200 (w), 1162 (w), 1047 (w), 1019 (w), 982 (m), 932 (w), 860 (w), 819 (w), 780
w), 733 (w), 706 (w), 650 (w), 597 (w), 562 (w).
(
+
2 -
2
.2.2. Synthesis of cyclohexanaminium cyclohexylcarbamodithioate, c-C H NH (L )
6 12 3
6

+
1 -
An analogous method to that used for the preparation of c-C H NH (L ) was followed
3
6
3
using cyclohexylamine (1.00 mL, 0.86 g, 8.67 mmol) and carbon disulfide (0.25 mL, 0.33 g,
.33 mmol). Colorless crystals suitable for X-ray analysis were obtained upon slow evaporation
of a methanolic solution of the product. Yield 1.0 g (90%). M.p.: 182-183 °C (176-178 °C [30],
88-189 °C [31,32]), Anal. found: C, 56.68; H, 9.80; N, 10.02. Calcd. for C H N S : C, 56.88;
4
1
13
26
2 2
1
H, 9.55; N, 10.21%. H NMR (CDCl +DMSO-d ) δ (ppm): 7.49 (s, 1H, NH), 5.93 (bs, 3H,
3
6
H
1
3
3
NH), 4.17-4.15 (m, 1H, CH), 3.11-3.07 (m, 1H, CH), 2.07-1.10 (m, 20H, 10CH2). C NMR
(
CDCl +DMSO-d ) δ (ppm): 210.80 (C=S), 55.16 (CH), 50.10 (CH), 31.83, 30.90, 25.05, 24.37,
3
6
c
-
1
2
1
3.96 (CH ). IR absorption (cm ): 3316 (s), 2930 (s), 2855 (m), 1638 (m), 1481 (s), 1446 (w),
2
389 (w), 1340 (m), 1251 (w), 1154 (w), 1120 (w), 1090 (w), 1014 (w), 980 (m), 943 (m), 886
(m), 795 (w), 664 (w), 639 (w), 559 (w).
2
2
.3. Synthesis of diorganotin(IV) compounds 1-4
1
.3.1. Synthesis of [Me Sn(L )Cl] (1)
2
Me SnCl (0.10 g, 0.45 mmol) in dichloromethane (5 mL) was added dropwise to a
2
2
+
1 -
stirred solution of c-C H NH (L ) (0.08 g, 0.44 mmol) also in dichloromethane (5 mL). After 4
3
6
3
h under stirring a white precipitate was formed which was isolated by filtration, washed with
small amounts of dichloromethane and dried in vacuo. Crystals of 1 suitable for diffraction
studies were obtained after several successive attempts of slow evaporation of dichloromethane
solutions of the product. Yield: 0.09 g (62%). M.p.: 100-101 °C. Anal. found: C, 23.02; H, 4.03;
1
N, 4.50. Calcd. for C H ClNS Sn: C, 22.77; H, 3.82; N, 4.43%. H NMR (CDCl ) δ (ppm):
6
12
2
3
H
7
0
.89 (s, 1H, NH), 2.91-2.87 (m, 1H, CH), 1.32 (s, 6H, SnMe ), 0.95-0.93 (m, 2H, CH ), 0.87-
2 2
13
.81 (m, 2H, CH ). C NMR (CDCl ) δ (ppm): 203.26 (C=S), 30.80 (CH), 10.25 (CH ), 7.46
2
3
c
2
7

1
13 119
119
-1
(
J( C- Sn) 566 Hz, SnMe ). Sn NMR (CDCl ) δ (ppm): −158.4. IR absorption (cm ):
2 3 Sn
3
230 (s), 3038 (w), 1637 (m), 1536 (s), 1510 (s), 1397 (m), 1338 (m), 1193 (m), 1090 (w), 1054
(w), 988 (m), 955 (m), 915 (m), 788 (s), 663 (m), 554 (m).
1
2
.3.2. Synthesis of [Me Sn(L ) ] (2)
2
2
An analogous method to that used for the preparation of 1 was followed using Me SnCl
2
2
+
1 -
(
0.10 g, 0.45 mmol) and c-C H NH (L ) (0.17 g, 0.90 mmol). Colorless crystals of 2 suitable
3 6 3
for diffraction studies were obtained after several successive attempts of slow evaporation of
dichloromethane solutions of the product. Yield: 0.13 g (69%). M.p.: 128-129 °C. Anal. found:
1
C, 29.35; H, 4.09; N, 6.80. Calcd. for C H N S Sn: C, 29.07; H, 4.39; N, 6.78%. H NMR
1
0
18
2 4
(
CDCl ) δ (ppm): 7.62 (s, 2H, 2NH), 2.98-2.87 (m, 2H, 2CH), 1.56 (s, 6H, SnMe ), 0.93-0.87
3
H
2
1
3
(
m, 4H, 2CH ), 0.79-0.73 (m, 4H, 2CH ). C NMR (CDCl +DMSO-d ) δ (ppm): 201.06 (C=S),
2
2
3
6
c
1
13 119
119
2
9.36 (CH), 13.76 (CH ), 5.59 ( J( C- Sn) 317 Hz, SnMe ). Sn NMR (CDCl ) δ (ppm):
2 2 3 Sn
-1
−
273.3. IR absorption (cm ): 3188 (s), 2997 (w), 2930 (s), 2852 (m), 1634 (m), 1520 (s), 1448
(
m), 1379 (m), 1343 (m), 1252 (w), 1155 (w), 1084 (w), 988 (s), 889 (m), 789 (m), 738 (w), 644
m), 557 (w).
(
2
2
.3.3. Synthesis of [Me Sn(L ) ] (3)
2
2
An analogous method to that used for the preparation of 1 was followed using Me SnCl
2
2
+
2 -
(
0.10 g, 0.45 mmol) and c-C H NH (L ) (0.25 g, 0.90 mmol). Colorless crystals of 3 suitable
6 12 3
for diffraction studies were obtained after several successive attempts of slow evaporation of
dichloromethane solutions of the product. Yield: 0.15 g (66%). M.p.: 145-146 °C. Anal. found:
1
C, 38.88; H, 6.25; N, 5.60. Calcd. for C H N S Sn: C, 38.64; H, 6.08; N, 5.63%. H NMR
1
6
30
2 4
8

(
(
(
CDCl ) δ (ppm): 7.48 (s, 2H, 2NH), 3.93-3.87 (m, 2H, 2CH), 2.10-1.14 (m, 20H, 10CH ), 0.88
3
H
2
1
3
s, 6H, SnMe2). C NMR (CDCl ) δ (ppm): 204.16 (C=S), 55.29 (CH), 31.75, 24.93, 24.58
3
c
1
13 119
119
CH ), 4.74 ( J( C- Sn) 406 Hz, SnMe )
Sn NMR (CDCl ) δ (ppm): −270.5. IR
3 Sn
2
2 .
-1
absorption (cm ): 3214 (s), 2979 (m), 2849 (w), 1636 (m), 1511 (s), 1420 (w), 1368 (m), 1334
(
s), 1208 (w), 1182 (m), 1094 (w), 1027 (s), 1005 (w), 965 (m), 912 (m), 823 (w), 797 (s), 759
w), 699 (w), 636 (m), 558 (w).
(
2
2
.3.4. Synthesis of [n-Bu Sn(L ) ] (4)
2
2
An analogous method to that used for the preparation of 1 was followed using n-
+
2 -
Bu SnCl (0.10 g, 0.32 mmol) and c-C H NH (L ) (0.18 g, 0.65 mmol). Colorless crystals of 4
2
2
6
12
3
suitable for diffraction studies were obtained after several successive attempts of slow
evaporation of dichloromethane solutions of the product. Yield: 0.10 g (52%). M.p.: 127-128 °C.
Anal. found: C, 45.86; H, 7.02; N, 5.12. Calcd. for C H N S Sn: C, 45.44; H, 7.28; N, 4.82%.
2
2
42
2 4
1
3
1
1
H NMR (CDCl ) δ (ppm): 7.46 (d, J( H- H) 8 Hz, 2H, 2NH), 3.99-3.87 (m, 2H, 2CH), 2.15-
3
H
1
3
1
.55 (m, 20H, 10CH ), 1.50-0.85 (m, 18H, Sn(n-Bu)2). C NMR (CDCl ) δ (ppm): 201.18
2 3 c
1
13
119
(
C=S), 57.90 (CH), 34.39, 31.87, 28.40 (CH ), 26.32, 25.18, 24.66, 13.74 ( J( C- Sn) 289 Hz,
2
119
-1
Sn(n-Bu)2). Sn NMR (CDCl ) δ (ppm): −278.9. IR absorption (cm ): 3180 (s), 2988 (w),
3
Sn
2
926 (s), 2853 (m), 1634 (m), 1515 (s), 1448 (m), 1378 (m), 1340 (m), 1257 (w), 1185 (w), 1151
(
w), 1086 (w), 1050 (w), 1017 (w), 984 (s), 887 (m), 795 (w), 726 (w), 688 (w), 645 (m), 574
w).
(
2
.4. X-ray crystallography
9

The measurements were performed on an Agilent Technologies four-circle Gemini
diffractometer [34] using Mo K radiation ( = 0.71073 Å) from a fine-focus sealed X-ray
source. Full spheres of data were collected using omega scans of 0.5º per frame. Data reduction
was performed with CrysAlisPro [35]. Intensities were corrected for Lorentz and polarization
effects and empirical absorption corrections using spherical harmonics were applied [35]. The
structures were solved by direct methods using the SIR97 package [36] and refined with
SHELXL-2018/3 [37]. Calculations were performed using the WinGX System-Version 2018-3
[
38]. C-bonded hydrogen atoms were included in the refinement in calculated positions using the
riding model approximation with the U (H) defined as 1.2Ueq and 1.5U of the parent
iso
eq
methylene and methyl atoms, respectively. Hydrogen atoms attached to N were located from the
difference Fourier map and refined according to the riding model with U (H) as 1.5U of the
iso
eq
parent N-atom. Least square refinements with anisotropic thermal motion parameters for all the
non-hydrogen atoms were employed. Crystallographic data given in Table 1 and Table 2 present
a comparison of the structural parameters of the compounds and will be recurrently referred to in
the discussion of the structures (see below). Illustrative hydrogen-bond interactions are shown in
the Supplementary Material file, Figs. S20-S24, and data on such non-covalent contacts are
presented in Table S1.
3
. Results and discussion
.1. Synthesis and spectroscopic characterization of c-C H NH (L ) and c-C H NH (L )
+
1 -
+
2 -
3
3
6
3
6
12
3
and diorganotin(IV) compounds 1-4
1
0

Treatment of cyclopropylamine /cyclohexylamine with carbon disulfide in 2:1 molar ratio
+
1 -
in ethanol delivered the respective carbamodithioate salts c-C H NH (L ) and c-
3
6
3
+
3
2 -
C H NH (L ) in good yields instead of the carbamodithioic acid reported earlier [26]. The
6
12
+
1 -
diorganotin(IV) compounds were obtained via simple metathesis between the c-C H NH (L )
3
6
3
+
2 -
or c-C H NH (L ) salts and the diorganotin dichlorides in dichloromethane (Scheme 1). The
6
12
3
by-products were identified through their melting points as cyclopropanaminium chloride
(
cyclopropylamine hydrochloride), 85-86 °C [39] and cyclohexanaminium chloride
cyclohexylamine hydrochloride), 206-209 °C [40], the latter also by SCXRD. The structural
(
features of the carbamodithiolate salts and diorganotin(IV) compounds 1-4 were envisioned from
1
13
119
IR, H, C (additionally by Sn NMR for 1-4) spectroscopic methods and by SCXRD.
1
1

Scheme 1. Systematic representation of the reaction methodology for the preparation of c-
+
1 -
+
3
2 -
C H NH (L ) and c-C H NH (L ) carbamodithiolate salts and their reactions with
3
6
3
6
12
diorganotin dichloride to afford compounds 1-4.
-1
All the IR spectra displayed a characteristic broad band at around 3450 cm assigned to
ν(NH). A strong band due to ν(C-N) was detected at 1558 and 1481 cm for c-C H NH (L )
1
+
1 -
3
6
3
+
3
2 -
and c-C H NH (L ) , respectively, while in compounds 1-4 that band was perceived in the
6
12

1
-1
range 1512-1536 cm , coincidently well within the region (1450-1550 cm ) for the NCSN
thiourea group. Compounds 2-4 displayed a single strong vibration in the range 984 to 1027
1
2


1
cm , suggesting a bidentate binding of the dithiocarbamato moiety; in 1 the splitting of this band
corroborates an unsymmetrical binding environment [23,41]. However, bidentate bonding mode
of CS could not be determined on the basis of  value [ = (CS ) -(CS ) ] as (CS )
2
2 asy
2 sy
2 sy
band could not be assigned unambiguously, which was eventually confirmed from the results of
the single-crystal X-ray diffraction analysis (vide infra).
1
+
1 -
+
3
2 -
H NMR of c-C H NH (L ) and c-C H NH (L ) displayed the expected signals due to
3
6
3
6
12
1
3
NH and NH protons, as well as the multiplets due to CH and CH proton(s). The C NMR
3
2
spectra for these salts revealed the C=S groups as well as the CH and CH resonances of
2
cyclopropyl and cyclohexyl moieties (see experimental for specific assignments). The absence of
1
13
H and C NMR signals for cyclopropanaminium and cyclohexanaminium moieties in 1-4
confirmed elimination of the cationic species as their anaminium chlorides (hydrochlorides). The
1
H NMR spectra of 1-4 showed the expected signals due to NH, CH, CH and SnMe /Sn(n-Bu)
2
2
2
groups with adequate integration values and confirming the
presence of
cyclopropylcarbamodithioate and cyclohexylcarbamodithioate ligands; the corresponding carbon
1
3
119
signals in the C NMR were also detected. The Sn NMR spectra in CDCl solution displayed
3
1
a sharp singlet at −158.4 ppm for [Me Sn(L )Cl] (1) and in the  range of −270.5 to −278.9 for
2
1
19
rest of the complexes. The observed ( Sn) chemical shifts are consistent with the presence of
five- (in 1) and six-coordinate (in 2-4) complexes in solution [42,43]. The solution NMR data
could not distinguish whether the dithiolate ligands are coordinated in the mono- or bidentate
1
13
mode. The structures of all the compounds were confirmed by SCXRD (see below). The J( C-
1
19
Sn) NMR coupling constants were used to estimate the C-Sn-C bond angle in solution using
the relationship established by Lockhart et. al [44]. For compound 1 the calculated angle of 126°
is similar to solid-state values of 128.5(3) (Sn1) and 130.4(3)° (Sn2) (Table 2, entry 8),
1
3

suggesting the square pyramidal structure is retained in solution. On the other hand, calculated
values for compounds 2-4 of 105, 112 and 102° are significantly lower than 134.7(2), 132.4(2)
and 140.2(4)°, respectively, suggesting the skewed trapezoidal bipyramid arrangement is not
119
retained in solution. When considered together with Sn NMR chemical shifts indicative of
hexacordination, the calculated C-Sn-C bond angles suggest a distorted octahedral arrangement
for compounds 2-4 in solution.
3
.2. Description of the crystal structures
+
1 
+
3
2 
The asymmetric units of c-C H NH (L ) and c-C H NH (L ) are displayed in Fig. 1,
3
6
3
6
12
each one including one anaminium cation and one dithiocarbamate anion. The cyclohexyl rings
+
2 
in c-C H NH (L ) adopt the chair conformation. The ellipsoid plots of the diorganotin(IV)
6
12
3
compounds 1-4 are displayed in Figs. 2-5. The asymmetric units of the diorganotin(IV)
compounds 2-4 (Figs. 3-5) contain one neutral molecule with the Sn cation in skewed trapezoidal
bipyramid geometry.
Fig. 1. Ellipsoid plots (drawn at 30% probability level) of the asymmetric units of c-
+
1 -
+
2 -
C H NH (L ) (left) and c-C H NH (L ) (right) with partial atom labeling schemes.
3
6
3
6
12
3
1
4

Intermolecular hydrogen-bond interactions are represented as dashed light-blue lines. Symmetry
+
1 -
operation to generated equivalent atoms: in c-C H NH (L ) , i) x,1/2-y,1/2+z; ii) x,1/2-y,-1/2+z;
3
6
3
iii) x,1.5-y,1/2+z; iv) x,1.5-y,-1/2+z; v) x,1+y,1+z; vi) x,-1+y,-1+z; vii) -x,1/2+y,1/2-z; viii) -x,-
+
2 -
1
/2+y,1/2-z. In c-C H NH (L ) , i) -x,1/2+y,1/2-z; ii) -x,1-y,1-z; iii) -x,-1/2+y,1/2-z.
6 12 3
Fig. 2. Ellipsoid plot (drawn at 30% probability level) of the asymmetric unit of 1 with partial
atom labeling scheme. Intermolecular hydrogen-bond interactions are represented as dashed
light-blue lines. Symmetry operation to generated equivalent atoms: i) 1/2-x,-1/2+y,1.5-z; ii) 1/2-
x,1/2+y,1.5-z; iii) 1.5-x,-1/2+y,1.5-z; iv) 1.5-x,1/2+y,1.5-z; v) 1/2-x,-1/2+y,1.5-z; vi) 1/2-
x,1/2+y,1.5-z; vii) -1/2+x,-1/2-y,1/2+z; viii) 1/2+x,-1/2-y,-1/2+z; ix) 1.5-x,-1/2+y,1.5-z; x) 1.5-
x,-1/2+y,1.5-z.
1
5

Fig. 3. Ellipsoid plot (drawn at 30% probability level) of the asymmetric unit of 2 with partial
atom labeling scheme. Intermolecular hydrogen-bond interactions are represented as dashed
light-blue lines. Symmetry operation to generated equivalent atoms: i) 1/2-x,-y,-1/2+z; ii) 1/2-x,-
y,1/2+z; iii) 1/2-x,-1/2+y,z.
1
6

Fig. 4. Ellipsoid plot (drawn at 30% probability level) of the asymmetric unit of 3 with partial
atom labelling scheme. Intermolecular hydrogen-bond interactions are represented as dashed
light-blue lines. Symmetry operation to generated equivalent atoms: i) 1-x,1-y,1-z; ii) 2-x,-y,1-z.
1
7

Fig. 5. Ellipsoid plot (drawn at 30% probability level) of the asymmetric unit of 4 with partial
atom labeling scheme. Intermolecular hydrogen-bond interactions are represented as dashed
light-blue lines. Symmetry operation to generated equivalent atoms: i) 1-x,1-y,1-z; ii) 1-x,2-y,2-
z.
1
8

The coordination positions include two alkyl and two bidentate dithiocarbamate ligands.
In each compound one of the SSn distance is longer (between 2.993(1) and 3.114(1) Å, Table 2
entry 5) than the other (between 2.4778(11) and 2.5167(10) Å, Table 2 entry 4) but is still shorter
than the sum of the van der Waals radii of the corresponding atoms (1.89 Å for sulfur and 2.42 Å
for tin) [45]. The Sn-C distances and C-Sn-C angles (entries 3 and 8) are in the range of those
found in the literature. The S-C-S angles (entry 7) are generally slightly smaller than those in c-
+
1 -
+
3
2 -
C H NH (L ) and c-C H NH (L ) . The S-SnS angles (denoted as intra-ligand S-Sn-S angles,
3
6
3
6
12
Table 2 entry 9) vary from 63.14(3) to 64.97(3)º. The S-Sn-S angles, either involving the short
between 80.48(3)-82.96(3)º] or the long Sn-S distances [between 148.69(3)-152.77(3)º; Table 2,
[
entry 10], fall in the range already reported, enabling classifying 2-4 in the series of compounds
with structural Motif I [8]. The stereochemical effect of the N-substituent of the dithiocarbamate
as well as of the alkyl ligands is clearly revealed by the angle between the least-square planes of
the NCS groups (entry 12). For example, comparing the dimethyltin(IV) complexes 2 and 3 the
2
bulky cyclohexyl substituents in the latter decreases that angle (entry 12) to 1.86 º (in 3) as
compared to that in the former (9.63º in 2). This conceivably results in a compression of the
crystal packing in 3 as revealed by the decrease of the shortest intermolecular SnSn distance
(entry 14). In contrast, when examining the cyclohexyl dithiocarbamate complexes 3 and 4, the n-
butyl groups in the latter impose a relative turning of the NCS groups increasing the referred bite
2
angle from 1.86 to 12.87º (entry 12) as well as the SnSn distance (entry 14).
The asymmetric unit of 1 contains two neutral Sn(IV) complex molecules each displaying a square
pyramidal geometry (entry 1,  of 0.43) [46] with a chelating dithiocarbamate and a chloride
5
ligand occupying the equatorial plane and the alkyl moieties the axial site. A noticeable effect of
the chloride anion is a shortening of the Sn-S lengths (in the 2.4518(14) - 2.7751(17) Å range,
1
9

entry 4) as well as the S-C-S and the C-Sn-C angles (entries 7 and 8, respectively), in comparison
to what was obtained in the other complexes (see above and Table 2). The Sn-C distances (entry
3
1
) are in the range of the ones in 2-4. A broader range of C-Sn-S angles was measured in 1 (entry
1).
The considerably shorter intermolecular SnSn distance in 1, as compared to the other
compounds (entry 14), can be related to the van der Waals SCl contacts (entry 13). Evaluating
the cohesion force in 1 through the estimation of the contact parameter  (eq. 1, where dAB is the
contact distance between atoms A and B, and vdW and vdW the respective van der Waals radii)
A
B
[
47], the obtained values of +0.44 Å for the SCl interaction (also, +0.52 Å for the SS and
0.69 Å for the ClCl ones) classifies it as very weak and irrelevant for the packing of the
molecules in the crystal.
= dAB  vdW  vdWB
+

(1)
A
Sets of tentative hydrogen-bond interactions (Table S1) could be detected in compounds 1-
+
1 -
4
(Figs. S20-S23) with relevance for the N-HS (or Cl, in 1), as well as in c-C H NH (L ) and c-
3
6
3
+
3
2 -
C H NH (L ) . Such interactions make infinite 1D chains in all cases, but in 2 there is the
6
12
possibility of expansion to the second dimension resulting from CHS contacts. Indeed, for all the
tin(IV) compounds the  parameter for the N-HS between 0.38 and 0.55 [47] (Table S1) are
reasonably strong (the negative values for the  parameter are indicative of overlapping of the van
der Waals spheres) [48] and stresses the role of such contacts in extending the structure to higher
dimension. The higher  values for the ammonium dithiocarbamate salts [0.79 Å in c-
+
1 -
+
3
2 -
C H NH (L ) and 0.76 Å in c-C H NH (L ) ] reveals a tighter packing structure in these
3
6
3
6
12
cases, conceivably due to the absence of coordination to a metal cation.
2
0

The 3D Hirshfeld surfaces and 2D fingerprint plots were used to further investigate the
interactions between molecules of each of the compounds, the latter being a useful method for the
quantification of the different interactions [49-51]. The plots over dnorm (Fig. 6 and Fig. S24) were
obtained with the CrystalExplore software, version 17.5 [50], and consider the distances to the
surface from nuclei outside (d ) and inside (d ) the Hirshfeld surface. These surfaces were drawn in
e
i
transparent mode to visualize the molecules that gave rise to them: the red color indicates the
stronger intermolecular contacts, the white those around the van der Waals radii range, and the
blue the weaker contacts. In every structure the predominance of the SH (or the ClH in 1)
interactions over the CH and the NH contacts is shown by the vivid red areas on the Hirshfeld
surfaces.
The fingerprint plots of the pro-ligands and compounds 1-4 have identical overall shapes
(Fig. 7). A comparison of the percentages of contribution to the total of each Hirshfeld surface is
presented in Fig. 8. It can be ascertained that in every case the major contribution is from HH
contacts. These are followed by the SH (the ClH interaction of 22.1 % in 1 also plays a
significant role in the respective total surface), and then the CH and the NH contacts with a
+
1 
+
2 
much lower influence. Since c-C H NH (L ) , c-C H NH (L ) and 1 comprise two entities
3
6
3
6
12
3
(ions or molecular units) in the structure, it is expected [52] that each component would have a
different contribution to the overall Hirshfeld surfaces as shown also in Fig. 8. Indeed, in
compound 1 the Sn2 molecule has a slightly higher contribution to the SH and ClH
intermolecular contacts than the Sn1 molecule (Fig. 8, middle). Concerning the dithiocarbamate
salts (Fig. 8, bottom), the anions are the largest contributors to the SH interactions, while the
cations are for the HH contacts.
2
1

Only in compound 2 is the shortest d + d distance of the HH type (ca. 2.0 Å); in the
e
i
remaining cases the shortest HH and SH contacts have identical values (between ca. 2.2 and
.5 Å), while for the ClH (in 1) the shortest value reaches ca. 2.7 Å. Other intermolecular
2
contacts not referred to above contribute less than 1% of the total volume of the Hirshfeld
surfaces.
2
2

NH +
(L )
1 
C
6
H
12NH +
(L )
2 
C
3
H
6
3
3
1
2
3
4
Fig. 6. Depiction of the dnorm Hirshfeld surfaces of the compounds in transparent mode.
2
3

+
1 
12NH +
(L )
2 
C
3
H
6
NH
3
(L )
C
6
H
3
1
2
3
4
Fig. 7. Fingerprint plots for the compounds with offset representations of the SH contributions
also ClH for 1) to the total Hirshfeld surfaces.
(
2
4

2
5

Fig. 8. Percentage contribution to the total Hirshfeld surface of the interactions in every
compound (top), individual contributions of the molecules in 1 (middle), and of each ion in the
dithiocarbamate salts (bottom).
4
. Conclusion
An efficient and highly practical method for the synthesis of new diorganotin(IV)
dithiocarbamates is described. Cyclopropanaminium cyclopropylcarbamodithioate and
cyclohexanaminium cyclohexylcarbamodithioate salts produced new diorganotin(IV)
dithiocarbamates upon reactions with diorganotin dihalide by metathesis. The method can be
considered as environmentally friendly since sodium/potassium/ammonium hydroxides,
commonly used in the preparation of Na/K/NH -dithiocarbamates, were avoided. The advantages
4
of the described protocol are due to the synthetic simplicity, high to excellent yield of products,
and the ability of the obtained carbamodithioate salts to react with organometal compounds in
one step. The HH intermolecular contacts are the main contributors to the total volume of the
Hirshfeld surfaces, followed by the SH interactions. In cases where there are more than one
component in the crystal (as in the structures of 1 and of the dithiocarbamate salts) the individual
entities contribute in slightly different extents to the overall Hirshfeld surface.
Conflict of interest
The authors declare that they have no conflicts of interest with the contents of this article.
Acknowledgements
2
6

Financial support from the Department of Biotechnology, India (Grant No.
BT/PR25263/NER/95/1104/2017, TSBB) and Fundação para a Ciência e a Tecnologia (FCT),
Portugal, (projects UID/QUI/00100/2019 and multiannual funding 2020-2023 to Centro de
Quimica Estrutural, MFCGS) are gratefully acknowledged. MRA thanks University Grants
Commission for the award of non-NET and UGC-JRF fellowships. TSBB and MRA
acknowledge access to DST-PURSE for the diffractometer facility.
Appendix A. Supplementary data
CCDC-2013890-2013895 contains the supplementary crystallographic data for the compounds
+
3
1 -
+
2 -
reported in this paper: c-C H NH (L ) (2013892), c-C H NH (L ) (2013894) and 1
3
6
6
12
3
(2013890), 2 (2013895), 3 (2013891) and 4 (2013893). These data can be obtained free of charge
via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or from the Cambridge Crystallographic
Data Center, 12 Union Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail:
deposit@ccdc.cam.ac.uk.
1
13
119
IR spectra (Figs. S1-S6). H, C, and Sn NMR spectra (Figs. S7-S19), X-ray: H-bonding
interactions (Figs. S20-S23), Hirshfeld surfaces (Fig. S24), structural parameters involving H-
+
1 -
+
2 -
bond interactions in c-C H NH (L ) , c-C H NH (L ) and 1-4 (Table S1).
3
6
3
6
12
3
CREDIT AUTHOR STATEMENT
T. S. Basu Baul: Conceptualization, Methodology, Supervision, Project administration, Funding
acquisition, Writing - Review & Editing. Maheswara Rao Addepalli: Investigation,
Methodology, Data curation. Andrew Duthie: Investigation, Visualization, Writing - Review &
2
7

Editing. M. Fátima C. Guedes da Silva: Analysis, Validation, Review & Editing, Funding
acquisition.
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