Synthesis, polarity, and structure of 2-chloro-N-[2-(methylsulfanyl)phenyl]- and 2-(diphenylthiophosphoryl)-N-[2-(methylsulfanyl)phenyl]acetamides

Article abstract of DOI:10.1134/S107042801507009X

Conformations of 2-chloro-N-[2-(methylsulfanyl)phenyl]- and 2-(diphenylthiophosphoryl)-N-[2-(methylsulfanyl)phenyl]acetamides have been studied by the dipole moment method and quantum chemical calculations. 2-(Diphenylthiophosphoryl)-N-[2-(methylsulfanyl)

Full text of DOI:10.1134/S107042801507009X

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2015, Vol. 51, No. 7, pp. 943–946. © Pleiades Publishing, Ltd., 2015.
Original Russian Text © E.A. Ishmaeva, A.Z. Alimova, Ya.A. Vereshchagina, D.V. Chachkov, O.I. Artyushin, E.V. Sharova, 2015, published in Zhurnal
Organicheskoi Khimii, 2015, Vol. 51, No. 7, pp. 963–966.
Synthesis, Polarity, and Structure
of 2-Chloro-N-[2-(methylsulfanyl)phenyl]- and 2-(Diphenyl-
thiophosphoryl)-N-[2-(methylsulfanyl)phenyl]acetamides
E. A. Ishmaevaa, A. Z. Alimovaa, Ya. A. Vereshchaginaa, D. V. Chachkovb,
O. I. Artyushinc, and E. V. Sharovac
a Kazan (Volga Region) Federal Uuniversity, ul. Kremlevskaya 18, Kazan, 420008 Tatarstan, Russia
e-mail: elenishmaeva@gmail.com
b Kazan Branch, Joint Supercomputer Center, Russian Academy of Sciences,
ul. Lobachevskogo 2/31, Kazan, 420111 Tatarstan, Russia
c Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences,
ul. Vavilova 28, Moscow, 119991 Russia
Received March 11, 2015
Abstract—Conformations of 2-chloro-N-[2-(methylsulfanyl)phenyl]- and 2-(diphenylthiophosphoryl)-
N-[2-(methylsulfanyl)phenyl]acetamides have been studied by the dipole moment method and quantum
chemical calculations. 2-(Diphenylthiophosphoryl)-N-[2-(methylsulfanyl)phenyl]acetamide has been found to
exist as an equilibrium mixture of two conformers with synclinal and anticlinal orientations of the Csp3‒Csp
and P=S bonds. 2-Chloro-N-[2-(methylsulfanyl)phenyl]acetamide is represented by one preferred conformer.
2
DOI: 10.1134/S107042801507009X
(Carbamoylmethyl)phosphine oxides are universal
bidentate ligands with a broad range of practical ap-
plications, e.g., in the radioactive waste processing [1].
Less common thiophosphoryl analogs of (carbamoyl-
methyl)phosphine oxides [2], as well as P(X)-modified
(carbamoylmethyl)phosphine oxides and sulfides
having a third coordination site (e.g., P=S group) [3],
are more appropriate ligand for the complexation and
purification of thiophiles (Ag, Pd, Pt, etc.). We have
synthesized a new complexing agent of this sort,
a thiophosphoryl analog of (arylcarbamoylmethyl)-
phosphine oxides having a methylsulfanyl group in the
benzene ring, and studied its structure in solution.
shown that phosphine oxide derivatives with a primary
amino group exist as only one conformer with intra-
molecular hydrogen bond.
In the present work we performed conformational
analysis of N-[2-(methylsulfanyl)phenyl]acetamides 1
and 2 by the dipole moment method and DFT quantum
chemical calculations with the B3PW91, wB97XD and
M06 functionals and 6-311++G(df,p) basis set. The
experimental dipole moments of compounds 1 and 2
were determined by the second Debye method
(Table 1). The coefficients of equations used in the cal-
culations and orientational polarizations are also given.
The structures of most favorable conformers of 1 and 2
are shown in figure. The theoretical dipole moments of
the energetically preferred conformers of 1 and 2 and
Conformational analysis of 2-aminophenyl-,
2-aminobenzyl-, and 2-nitrobenzyl(diphenyl)phos-
phine oxides by the dipole moment, vibrational spec-
troscopy, and quantum chemical methods [4] has
Table 1. Coefficients of equations used in the calculations,
orientational polarizations, and experimental dipole mo-
ments of compounds 1 and 2
SMe
SMe
Comp. no.
α
γ
Por., cm3
μ, D
NH
NH
S
P
Cl
Ph
Ph
1
2
4.669
3.696
0.187
0.425
181.968
224.762
2.97
3.37
O
O
1
2
943

ISHMAEVA et al.
944
1A
2A
2B
Structures of the most stable conformers of compounds 1 and 2 according to DFT quantum chemical calculations (some hydrogen
atoms are not shown).
their relative energies were calculated by the above
listed quantum chemical methods, and the dipole
moments of these conformers were calculated by the
vector addition method (Table 2).
bond (CCPS 37 and 13°), and the Csp3‒Csp2 bond is
gauche with respect to the latter (Csp3Csp2PS 71°). The
NHC(O)CH2 fragment in conformer 2B lies almost in
the benzene ring plane (CCNCsp2 3°); the phenyl
substituents on the phosphorus are oriented gauche
and cis with respect to the P=S bond (CCPS 33 and
21°), while the Csp3‒Csp2 bond is oriented trans
(Csp3Csp2PS 151°).
According to the calculations, the most favorable
conformer of 1 is 1A (∆E = 0.0 kJ/mol) where the
S‒CH3 bond is orthogonal to the benzene ring plane
(the dihedral angle CCSCH3 is 93°) and the planar
NHC(O)CH2Cl fragment lies almost in that plane
(CCNC 4°). This conformer features a nonclassical
C‒H···O contact between the 6-H hydrogen atom and
carbonyl oxygen atom; the H···O distance is 2.20
(B3PW91) or 2.22 Å (wB97XD, M06,). The relative
energies of other possible conformers of 1 are higher
than 25 kJ/mol. The experimental dipole moment of 1
is slightly larger than the theoretical one (Tables 1, 2),
whereas the dipole moment calculated by the vector
addition method is very consistent with the experi-
mental value.
Conformer 2A turned out to be the most stable
according to the B3PW91/6-311++G(df,p) calcula-
tions, and the energy of 2B was slightly higher.
Analysis of the μcalc values suggests conformational
equilibrium of 2A and 2B in solution at a ratio of
80:20. However, wB97XD/6-311++G(df,p) calcula-
tions showed conformer 2B to be preferred. Therefore,
the results were verified by the M06/6-311++G(df,p)
calculations which confirmed the wB97XD data. In
any case, the energy difference between conformers
2A and 2B is fairly small, so that conformational
equilibrium between 2A and 2B in solution is quite
possible.
Two stable conformers, 2A and 2B were found for
amide 2 by quantum chemical calculations. As in 1A,
the S‒CH3 bond in 2A and 2B is also orthogonal to the
benzene ring plane (the corresponding dihedral angles
CCSC are 99 and 90°, respectively), and the NHC(O)
CH2 fragment is planar. The NHC(O)CH2 fragment in
2A deviates from the benzene ring plane to form
a dihedral angle CCNC of 19°, the phenyl substituents
are oriented gauche and cis with respect to the P=S
Unlike conformer 2A, two C‒H···O contacts be-
tween ortho-hydrogen atoms of two benzene rings and
carbonyl oxygen atom were observed in conformer 2B;
the H···O distances are 2.20 and 2.22 Å (B3PW91) or
2.20 and 2.26 Å (wB97XD, M06).
Thus, 2-(diphenylthiophosphoryl)-N-[2-(methylsul-
fanyl)phenyl]acetamide (1) is conformationally het-
Table 2. Relative energies (ΔE, kJ/mol) of the most stable conformers of compounds 1 and 2 and their theoretical dipole
moments (μtheor, D) and dipole moments calculated by the vector addition method (μcalc, D)
B3PW91/6-311++G(df,p)
wB97XD/6-311++G(df,p)
M06/6-311++G(df,p)
Conformer
μcalc
ΔE
μtheor
ΔE
μtheor
ΔE
μtheor
1A
2A
2B
0.0
0.0
2.9
1.85
3.24
4.07
00.0
10.7
00.0
1.44
3.48
4.25
0.0
6.6
0.0
1.49
3.44
3.77
2.98
2.61
5.36
RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 51 No. 7 2015

SYNTHESIS, POLARITY, AND STRUCTURE OF 2-CHLORO-N-[2-(METHYLSULFANYL)...
945
of water were added to the residue, the organic phase
was separated and dried over Na2SO4, the solvent was
removed under reduced pressure, and the residue was
recrystallized from methanol. Yield 1.50 g (76%),
mp 141–142°C. IR spectrum (KBr), ν, cm–1: 3241,
3052, 2963, 1647 (C=O), 1521, 1526, 1438, 1435,
erogeneous, and it exists as an equilibrium mixture of
synclinal and anticlinal conformers. 2-Chloro-N-[2-
(methylsulfanyl)phenyl]acetamide (1), like 2-amino-
phenyl(diphenyl)phosphine oxide [4], exists as a single
conformer.
1
EXPERIMENTAL
1308, 1099, 748, 692. H NMR spectrum, δ, ppm:
3
4
9.40 br.s (1H, NH), 7.98 d.d (1H, 6-H, J = 8.0, J =
1.3 Hz), 7.87‒7.94 m (4H, m-H), 7.44‒7.56 m (6H,
The IR spectra were recorded on a Nicolet Magna
IR750 spectrometer. The 1H, 31P, and 13C NMR spectra
were measured on Bruker AV-300 and AV-400 spec-
trometers from solutions in CDCl3. 2-(Methylsulfanyl)-
aniline was commercial product (Aldrich). Compounds
1 and 2 were synthesized according to procedures
analogous to those reported by us previously [3].
3
4
o-H, p-H), 7.42 d.d (1H, 3-H, J = 7.7, J = 1.3 Hz),
3
4
7.18 d.t (1H, 5-H, J = 7.8, J = 1.3 Hz), 7.05 d.t (1H,
3
4
2
4-H, J = 7.6, J = 1.4 Hz), 3.73 d (2H, PCH2, JPH
=
14.0 Hz), 2.35 s (3H, CH3S). 13C NMR spectrum, δC,
ppm: 162.63 d (C=O, JPC = 4.7 Hz), 137.57 s (C1),
2
132.15 s (C6), 131.97 d (Cp, JPC = 3.3 Hz), 131.40 d
4
1
3
(Ci, JPC = 83.6 Hz), 131.08 d (Cm, JPC = 11.0 Hz),
2-Chloro-N-[2-(methylsulfanyl)phenyl]acet-
amide (1). A mixture of 1.39 g (0.01 mol) of
2-(methylsulfanyl)aniline and 1.01 g (0.01 mol) of
triethylamine in 10 mL of chloroform was cooled to
‒20°C, and 1.13 g (0.01 mol) of chloroacetyl chloride
was added dropwise under stirring. The mixture was
stirred for 2 h at ‒20°C, 20 mL of 5% aqueous HCl
was added, the organic layer was separated, and the
aqueous layer was extracted with 5 mL of chloroform.
The extracts were combined with the organic phase,
dried over Na2SO4, and evaporated under reduced
pressure, and the residue was subjected to silica gel
chromatography using hexane–methylene chloride
(5:3) as eluent. Yield 1.57 g (73%), mp 54–55°C. IR
spectrum (KBr), ν, cm–1: 3239 (NH), 3205, 1670
128.75 d (Co, JPC = 14.0 Hz), 127.91 s (C3), 127.54 s
2
(C2), 124.91 s (C5), 121.63 s (C4), 44.02 d (PCH2,
1JPC = 45.1 Hz), 18.93 s (CH3S). 31P NMR spectrum:
δP 37.40 ppm, s. Found, %: C 63.71; H 5.07; N 3.59;
P 7.73; S 16.23. C21H20NOPS2. Calculated, %:
C 63.45; H 5.07; N 3.52; P 7.79; S 16.13.
The dielectric permittivities of dilute solutions of 1
and 2 in benzene were determined at 25°C on a BI-870
instrument (Brookhaven Instruments) with an accuracy
of ±0.01. The refractive indices of these solutions were
measured with an accuracy of ±0.0001 using an RA-
500 refractometer (Kyoto Electronics). The dipole mo-
ments were calculated by the vector addition method
on the basis of geometric parameters determined by
quantum chemical calculations; the following bond
and group moments were used: m(P=>S) 3.29 D (cal-
culated from μexp of PhP=S [5]), m(Csp3→P) 0.83 D
[5], m(Ph→P) 1.09 D [6], m(C=>O) 1.94 D [6],
m(Csp3→Cl) 1.58 D (calculated from μexp of MeCl [7]),
m(N→H) 1.31 D (calculated from μexp of NH3 [7]),
m(Carom→N) 2.12 D (calculated from μexp of PhNH2
[7]), m[N→Csp2(O)] 0.94 D (calculated from μexp of
MeC(O)NH2 [7]), m(CH3→S) 1.14 D (calculated from
1
(C=O), 1538, 1443, 1407, 1271, 751. H NMR spec-
trum, δ, ppm: 9.52 br.s (1H, NH), 8.31 d.d (1H, 6-H,
3J = 8.0, 4J = 1.0 Hz), 7.51 d.d (1H, 3-H, 3J = 7.8, 4J =
3
4
1.0 Hz), 7.32 d.t (1H, 5-H, J = 7.3, J = 1.0 Hz),
3
4
7.12 d.t (1H, 4-H, J = 7.5, J = 1.0 Hz), 4.24 s (2H,
CH2Cl), 2.40 s (3H, CH3S). 13C NMR spectrum, δC,
ppm: 163.86 s (C=O), 137.27 s (C1), 133.04 s (C6),
128.85 s (C3), 126.10 s (C2), 125.05 s (C5), 120.18 s
(C4), 43.20 s (CH2Cl), 18.69 s (CH3S). Found, %:
C 50.21; H 4.67; N 6.47; S 14.97. C9H10ClNOS. Cal-
culated, %: C 50.12; H 4.67; N 6.49; S 14.86.
μexp of Me2S [7]), m(Carom→S) 0.30 D (calculated from
μexp of PhSH [7]), m(H→Csp3) 0.28 D [8], m(H→Csp2)
0.7 D [8].
2-(Diphenylphosphorothioyl)-N-[2-(methylsul-
fanyl)phenyl]acetamide (2). Sodium hydride, 0.12 g
(5 mmol; 60% suspension in oil), was added at 0°C to
a solution of 1.09 g (5 mmol) of diphenylphosphine
sulfide in 20 mL of THF, and the mixture was stirred
for 30 min until hydrogen no longer evolved. A solu-
tion of 1.08 g (5 mmol) of chloroacetamide 1 in 10 mL
of THF was added at 0°C to the resulting transparent
solution. The cooling bath was removed, and the mix-
ture was stirred for 24 h at 20°C. The solvent was
distilled off, 30 mL of methylene chloride and 10 mL
Quantum chemical calculations were performed
at the Kazan Branch, Joint Supercomputer Center,
Russian Academy of Sciences (http://wt.knc.ru) using
GAUSSIAN 09 software package [9] with full geom-
etry optimization. In all cases, stationary points were
identified as energy minima by calculating second
derivatives.
This study was performed under financial support
by the Russian Foundation for Basic Research (project
no. 13-03-00067a).
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ISHMAEVA et al.
7. Osipov, O.A., Minkin, V.I., and Garnovskii, A.D.,
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