Synthesis and Structure of N-Pyridyl-Containing Cyclic Aminomethylphosphines

Article abstract of DOI:10.1134/S1070363218110038

N-pyridyl-containing cyclic aminomethylphosphines have been prepared via condensation of the corresponding bis(hydroxymethyl)arylphosphines with p-aminopyridine and m-aminomethylpyridine.

Full text of DOI:10.1134/S1070363218110038

ISSN 1070-3632, Russian Journal of General Chemistry, 2018, Vol. 88, No. 11, pp. 2257–2262. © Pleiades Publishing, Ltd., 2018.
Original Russian Text © Yu.S. Spiridonova, E.I. Musina, I.R. Dayanova, O.E. Naumova, I.A. Litvinov, A.A. Karasik, 2018, published in Zhurnal Obshchei
Khimii, 2018, Vol. 88, No. 11, pp. 1776–1781.
Dedicated to the 115th anniversary of B.A. Arbuzov’s birth
Synthesis and Structure
of N-Pyridyl-Containing Cyclic Aminomethylphosphines
Yu. S. Spiridonovaa*, E. I. Musinaa, I. R. Dayanovaa, O. E. Naumovaa,
I. A. Litvinova, and A. A. Karasika
a A.E. Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center, Russian Academy of Sciences,
ul. Akademika Arbuzova 8, Kazan, Tatarstan, 420088 Russia
*e-mail: aik791@gmail.com
Received September 13, 2018
Abstract—N-pyridyl-containing cyclic aminomethylphosphines have been prepared via condensation of the
corresponding bis(hydroxymethyl)arylphosphines with p-aminopyridine and m-aminomethylpyridine.
Keywords: aminomethylphosphine, pyridylphosphine, 1,5-diaza-3,7-diphosphacyclooctanes
DOI: 10.1134/S1070363218110038
Тransition metal сomplexes with 1,5-diaza-3,7-
diphosphacyclooctanes are mimetics of hydrogenases,
effective and inexpensive catalytic systems for
practically important processes of interconversion
between electrical energy and chemical bonds energy
which is essential for the development of alternative
energetics based on hydrogen [1, 2]. In particular, high
catalytic activity of bisligand nickel(II) complexes
with P2N2-ligands has been shown in the processes of
electrochemical hydrogen oxidation and proton
reduction of protons to hydrogen [3].
was synthesized in 1980, in 26% yield [6]. Despite the
description of molecular structure of this compound in
the crystal in 1999 [7], the study of its structure in the
solution has not been performed, yet this is necessary
for further investigation of structure and properties of
the related complexes.
This study aimed to synthesize aminomethyl-
phosphines containing pyridyl substituents at the
nitrogen atoms, including new compounds, and elucida-
tion of their structure in solution as well as in crystal-
line state.
According to [4, 5], the introduction of pyridyl
group to the phosphorous or nitrogen atom of the
ligand significantly increases the catalytic activity of
the complexes. This fact has been caused by the
possibility of secondary interactions, for example, the
formation of hydrogen bonds or proton transfer in the
coordination sphere, which is a background for the
creation of fuel cells. The introduction of pyridyl
substituent to the phosphorous atom requires the use of
pyridylphosphines which are difficult to synthesize.
The introduction of pyridyl substituents to the nitrogen
atom is simpler because the corresponding amines are
commercially available.
The common method of the preparation of amino-
methylphosphines is the Mannich-like reaction in the
phosphine–formaldehyde–amine systems. This approach
allows preparation of various functionalized derivaives
using the corresponding functionalized amines [5–10].
The use of p-aminopyridine and m-aminomethyl-
pyridine in the condensation reaction has yielded a series
of N-pyridyl-containing cyclic aminomethylphosphines.
Bis(hydroxymethyl)phenyl and bis(hydroxymethyl)-
mesityl phosphines were prepared via addition of
paraformaldehyde at 100–110°С to the corresponding
primary phosphines as described in [11, 12]. Further
condensation with amines occurred under reflux in
ethanol during 8–10 h and led to the formation of the target
1,5-diaza-3,7-diphosphacyclooctanes 1–4 (Scheme 1)
with moderate yields (28–67%).
The first 1,5,3,7-diazadiphosphacyclooctane containing
pyridyl substituents at nitrogen atoms [1,5-di(2-
pyridyl)-3,7-phenyl-1,5,3,7-diazadiphosphacyclooctane]
2257

2258
SPIRIDONOVA et al.
Scheme 1.
ArPH2
110oC
7
8
N
N
8
9
N
N
7
Ar
P
9
N
6
6
N
Ar
P
2-PyNH2
10
OH 2-PyCH2NH2
10
N
N
P
EtOH, 80oC
11
ArP
EtOH, 80oC
1
P
Ar
OH
1
Ar
1, 2
3, 4
Me
3
2
3
4
4
2
5
5
(1, 3),
(2, 4).
Ar =
Me
Me
Compounds 1–4 are white crystalline powders
soluble in chloroform, acetone, and DMF, and stable in
air in solid state. Their structures were confirmed by
1Н, 31Р, and 13С NMR as well as IR spectroscopy (see
the table), their composition was confirmed by the
elemental analysis data.
shifted compared with the pyridyl-substituted analogs
1 and 2. In the 1Н NMR spectra of the studied
heterocycles except compound 1, methylene protons of
the heterocycle Н1 appeared as АВ-part of the (АВ)2Х-
system (two doublets of axial and equatorial protons
2
with spin-spin coupling constants JHH 13.9–14.7 Hz,
see the table). Such system is typical of diazadiphos-
phacyclooctanes in the chair–chair conformation with
equatorial substituents at the phosphorous atoms. It
should be noted that such pattern of the signals of
equatorial and axial protons of heterocycle is typical of
diazadiphosphacyclooctanes [8, 13]. In the spectrum of
Р-phenyl substituted heterocycle 1 in CDCl3, АВ-part
of the (АВ)2Х-system was registered as two doublets
of axial and equatorial protons with 2JHH = 14.5 Hz and
The IR spectra of the pyridylphosphines contained
characteristic bands of ν(Py) vibrations at 1422–1481
and 1574–1602 cm–1 and did not contain the bands
assignable to the vibrations of amino and hydroxy
groups. That fact indicated cyclic structure of the
investigated compounds. The NMR spectra evidenced
symmetric structure of heterocycles 1–4 in solutions.
Each 31Р NMR spectrum contained a single signal (see
the table) in the range typical of Р-phenyl- and Р-mesityl-
substituted diazadiphosphacyclooctanes [12]. The
signals of heterocycles 3 and 4 containing methyl-
pyridyl substituents at nitrogen atoms are upfield
2
2JРH = 4.1 Hz for axial and JРH = 8.92 Hz for
equatorial protons. The signals of aromatic proton of
compounds 1–4 were observed in the characteristic
region. In the spectra of compounds 3 and 4, signals of
Yields and spectroscopic parameters of 1,5-diaza-3,7-diophosphacyclooctanes 1–4
Н1
Н1
eq
2JНН
ax
Comp.
no.
Yield, %
δР, ppma
δН, ppmb
3.95
2JНН
14.5
2JPН
4.12
δН, ppmb
4.84
2JPН
8.92
1
2
3
4
41
68
28
31
–40.05
–33.55
–67.17
–78.14
14.50
14.67
13.95
14.30
4.35
14.67
13.95
14.30
14.67
13.95
14.30
4.82
14.67
13.95
14.30
3.47
3.69
3.55
4.17
a Solvent DMF. b Solvent CDCl3.
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SYNTHESIS AND STRUCTURE OF N-PYRIDYL-CONTAINING
2259
Fig. 2. The general view of a molecule of compound 2 in
the crystal.
Fig. 1. The general view of a molecule of compound 1 in
the crystal.
pyridyl protons are found at 7.18 and 7.13 (С9Н), 7.66
and 7.59 (С10Н), 8.45 and 8.40 (С8Н), 8.59 and
8.50 ppm (С7Н), respectively. The signals of P-phenyl
substituents in the spectrum of compound 3 are
registered as multiplet signal at about 7.27 ppm and are
partially overlapped with the solvent signal (CDCl3).
The signals of the Н4 atoms of mesityl fragments are
registered as singlet at 6.81 ppm in the spectrum of
compound 4. Methylene protons of the NCH2Py
fragment are registered as singlet at 4.21 (3) and
4.27 ppm (4).
analysis (Figs. 1 and 2). The conformation of the
heterocycles in those molecules was the same: the
eight-membered cycles in the crystal as well as in
solution have the chair–chair conformation typical of
diazadiphosphacyclooctanes [8, 10, 12]. Aromatic
substituents at the phosphorous atoms are in equatorial
positions, pyridyl substituents at the nitrogen atoms are
in axial positions. The observed geometry parameters
of the eight-membered cycles are typical of diaza-
diphosphacyclooctane: the Р···Р distances are 3.60–
4.05 Å, the N···N distances are 3.75–4.11 Å. The
nitrogen atoms of the heterocycles in both cases have
practically undistorted planar triangle coordination
(sum of bond angles in both cases was 359°) because
of the conjugation with aromatic substituents. The
pyridyl rings are in the eclipsed conformation with the
bonds of nitrogen in the heterocycle. As a result, they
could not coordinate metal atoms, and molecules of
compounds 1 and 2 could act only as chelate ligands
involving two phosphorous atoms simultaneously,
which is typical of 1,5-diaza-3,7-diphosphacyclo-
octanes [4–8, 10–12]. Phenyl- and mesityl-substituted
heterocycles 1 and 2 are differ from each other by
position of aromatic rings of the substituents at
phosphorous atoms relative to heterocycle: in the case
of compound 2 these rings are located near its bisector
plane (going through phosphorous atoms), in contrast,
phenyl cycles in the molecule of compound 1 are
practically eclipsed by one of the endocyclic Р–С
bonds, which is typical of Р-mesityl- and Р-phenyl-
substituted diazadiphosphacyclooctanes [12].
In the case of 2-pyridyl substituted compound 1, the
signals of the Н3 and Н5 atoms of phenyl substituents
at the phosphorous atoms and of the proton at the С9
atom overlapped, forming a multiplet signal at
7.41 ppm. The signals of the protons at the С8 and С10
atoms are also present as multiplet signal at
6.55 ppm. The Н4 atoms of P-phenyl substituents and
the proton at the С7 atom are registered as a doublet of
doublets at 7.66 and doublet of doublets of doublets at
8.18 ppm. In the spectra of compound 2, the signals of
pyridyl protons at the С10, С8, С9, and С7 atoms are
registered at 6.25, 6.49, 7.33, and 8.09 ppm,
respectively. The signal of the Н4 atom of mesityl
substituent was observed as a singlet at 6.94 ppm.
Moreover, in the spectra of Р-mesityl-substituted
compounds 2 and 4, the narrow signals of methyl
groups in the meta-position of the mesityl moieties are
observed at 2.31–2.54 and 2.21–2.51 ppm,
respectively. The equivalence of the methyl groups
indicated free rotation about the exocyclic Р–С bonds
at room temperature.
In summary, new N-pyridyl-containing ligands,
1,5,3,7-diazadiphosphacyclooctanes, are prepared and
their structure was elucidated. The obtained ligands are
The structure of pyridylphosphines 1 and 2 in crys-
talline state was investigated using X-ray diffraction
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 88 No. 11 2018

2260
SPIRIDONOVA et al.
of interest as precursors in the synthesis of Ni(II)-
complexes for testing in electrocatalytic systems of
hydrogen production and as promising precursors in
the synthesis of various coordination compounds with
other catalytically active metals [Fe(II), Ru(II)] and
metals of copper group [Cu(I), Au(I), Ag(I)] for
constructing photoluminescence systems.
Crystals of compound 2 were colorless, prismatic,
triclinic, C32H38N4Р2, M = 540.60, a = 8.6122(11) Å,
b = 13.2875(17) Å, c = 14.4152(18) Å, α = 108.247(2)°,
β = 96.890(2)°, γ = 104.003(2)°, V = 1485.4(3) Å3,
dcalc = 1.209 g/cm3, Z = 2, space group P-1. Scanning
over 2.1° < θ < 27.00°, μ(Mo) = 0.174 mm–1. 11918
reflections were collected, 5447 independent
reflections were collected, including 1790 with I ≥ 2σ.
Final values of R factors: R = 0.0420 and Rw = 0.0449
over reflections with F > 2σ(F2), R = 0.1668 and Rw =
0.0638 over all 5447 reflections, goodness of fit
(Good) 0.638.
EXPERIMENTAL
The 31Р NMR spectra were recorded using a Bruker
CXP-100 spectrometer (161 MHz, 85% Н3РО4). The
1Н and 13С NMR were recorded using a Bruker
Avance-400 instrument (400 and 100 MHz, respec-
tively). The IR spectra were registered using a Bruker
Vector-22 spectrometer in the 4000–400 cm–1 range in
KBr pellets. Melting points were measured using a
Boetius apparatus in sealed capillaries without
calibration.
The crystallographic data were deposited at the
Cambridge Crystallographic Data Center [CCDC
1867232 (1) and 1867236 (2)].
All reactions and manipulations were conducted
under a Ar atmosphere using standard Schlenk tech-
niques, and all solvents were degassed with argon.
PhPH2 and MesPH2 were prepared as described in
[11, 12]. o-Aminopyridine and m-aminopyridine were
commercially available.
X-ray diffraction data for crystals of compounds 1
and 2 were collected using a Bruker Smart APEX II
CCD automatic diffractometer [graphite monochro-
mator, λ(MoKα) = 0.71073 Å, ω-scanning, 293(2) K].
Extinction was accounted for semiempirically using
SADABS software [14]. Structures were solved via the
direct methods using SIR software [15] and refined
first under isotropic and then under anisotropic approxi-
mation using SHELXL-97 software [16]. Positions of
H atoms were found geometrically and included in the
refinement using the rider model. The calculations
were performed using WinGX software [17] and
APEX2 software [18]. Plotting and analysis of inter-
molecular interactions were performed using PLATON
[19] and ORTEP software [20]. Investigation of the
crystals was carried out at Federal Spectral Analytical
Center for Joint Usage, Arbuzov Institute of Organic
and Physical Chemistry (Laboratory of Diffraction
Methods).
General procedure of synthesis of compounds 1–4.
A mixture of 4.45 mmol of phenylphosphine and
9 mmol of paraformaldehyde was heated to 90°С until
complete dissolution of paraformaldehyde. The ob-
tained bis(hydroxymethyl)phenylphosphine was dissolved
in 20 mL of degassed ethanol. Then 4.44 mmol of the
corresponding amine was added. The reaction mixture
was stirred at 100°С for 10 h. The precipitate was
filtered off, washed with degassed ethanol, and dried at
a reduced pressure for 3 h.
1,5-Di-(2-pyridyl)-3,7-phenyl-1,5,3,7-diazadiphos-
phacyclooctane (1). Yield 41%, mp 206–208°С. IR
1
spectrum, ν, cm–1: 1481 (Py), 1591 (Py). Н NMR
2
spectrum (CDCl3), δ, ppm: 3.95 d. d (4H, HB, JHH
=
2
2
14.5, JPH = 4.1 Hz), 4.84 d. d (4H, HA, JHH = 14.5,
2JPH = 8.9 Hz), 6.55–6.60 m (4H, H8,9), 7.41 m (9Н, H3,
H5, H10), 7.66 d. d (4H, H4,4', 3JHH = 6.3, 4JPH = 1.5 Hz),
Crystals of compound 1 were colorless, prismatic,
monoclinic, C26H26N4Р2, M = 456.45, a = 26.834(4) Å,
b = 10.5282(16) Å, c = 19.562(3) Å, β = 121.782(2)°,
V = 4697.9(12) Å3, dcalc = 1.291 g/cm3, Z = 8, space
group С2/c. Scanning over 2.1° < θ < 26.00°, μ(Mo) =
0.207 mm–1. 11543 reflections were collected, 4578
independent reflections were collected, including 3085
with I ≥ 2σ. Final values of R factors: R = 0.0435 and
Rw = 0.1348 over reflections with F > 2σ(F2), R =
0.0732 and Rw = 0.1747 over all 4578 reflections,
goodness of fit (Good) 0.725.
8.18 d. d. d (2H, H7, JH4H3 = 4.9, JH4H2 = 1.9, JH4H1 =
0.2 Hz). 31P NMR spectrum (DMF): δP –40.05 ppm.
Found, %: C 67.73; H 5.72; N 13.00; P 13.12.
C26H26N4P2. Calculated, %: C 68.42; H 5.70; N 12.28;
P 13.60.
3
4
5
1,5-Di-(2-pyridyl)-3,7-dimesityl-1,5,3,7-diazadiphos-
phacyclooctane (2). Yield 68%, mp 204–206°С. IR
1
spectrum, ν, cm–1: 1481 (Py), 1591 (Py). Н NMR
spectrum (CDCl3), δ, ppm: 2.31 s (6H, Me5), 2.54 s
RUSSIAN JOURNAL OF GENERAL CHEMISTRY Vol. 88 No. 11 2018

SYNTHESIS AND STRUCTURE OF N-PYRIDYL-CONTAINING
2261
2
(12H, Me3), 4.35 d (4H, H1, JHH = 14.7 Hz), 4.82 d
the Russian Foundation for Basic Research (project
no. 18-03-00833 A, synthesis of ligands).
(4H, H1, JHH = 14.7 Hz), 6.25 d (2H, H10, JH1H2 =
2
3
8.6 Hz), 6.49 d. d (2Н, H8, JH3H2 = 7.1, JH3H4 =
3
3
4.9 Hz), 6.94 s (2H, H4), 7.33 d. d. d (2H, H9, JH2H3 =
3
CONFLICT OF INTERESTS
No conflict of interests was declared by the authors.
REFERENCES
7.1, JH2H1 = 8.6, JH2H4 = 1.8 Hz), 8.09 d. d (2H, H7,
3
4
3JH4H2 = 4.9, JH4H2 = 1.8 Hz). 13C NMR spectrum
4
(DMF-d7), δС, ppm: 20.34 (Me5), 23.20 (Me5), 52.23 d
(C1, JPC = 18.3 Hz), 107.56 (C10), 111.59 (C8), 129.43
1
(C4), 131.69 d (C2, JPC = 25.9 Hz), 136.52 (C9),
1
139.18 (C3), 144.22 (C5), 147.75 (C7), 156.45 (C6). 31P
NMR spectrum (DMF): dР –33.55 ppm. Found, %: C
70.39; H 7.69; N 10.09; P 14.33. C32H42N4P2. Cal-
culated, %: C 71.11; H 7.04; N 10.37; P 14.48.
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1,5-Di-(3-methylpyridine)-3,7-diphenyl-1,5,3,7-
diazadiphosphacyclooctane (3). Yield 28%, mp 166–
168°С. IR spectrum, ν, cm–1: 1574 (Py), 1422 (Py). 1Н
NMR spectrum (CDCl3), δ, ppm: 3.47 d (4H, H1, 2JHH
=
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2
13.9 Hz), 3.69 d (4H, H1, JHH = 13.9 Hz), 4.21 s (4H,
H11), 7.18 d. d (2H, H9, JH3H4 = 7.7, JH3H2 = 4.9 Hz),
3
3
7.27 m (10Н, H3–5), 7.66 d (2H, H10, JH3H4 = 7.7 Hz),
3
8.45 d (2H, H8, JH3H2 = 4.9 Hz), 8.59 s (2H, H7). 13C
3
NMR spectrum (CDCl3), δС, ppm: 56.86 (C11), 61.48
(C1), 123.37 (C9), 128.76 d (C4, 1JPC = 3.6 Hz), 128.86
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(C5), 132.57 d (C3, JPC = 10.2 Hz), 133.89 (C6),
1
136.81 (C10), 138.84 d (C2, 1JPC = 5.6 Hz), 148.77 (C8),
150.64 (C7). 31P NMR spectrum (DMF): δP –67.17 ppm.
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C28H36N4P2. Calculated, %: C 69.42; H 6.20; N 11.57;
P 12.81.
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diazadiphosphacyclooctane (4). Yield 31%, mp 132–
134°С. IR spectrum, ν, cm–1: 1422 (Py), 1602 (Py). 1Н
NMR spectrum (CDCl3), δ, ppm: 2.21 s (6H, Me5),
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2
2.51 s (12H, Me3), 3.55 d (4H, H1, JHH = 14.3 Hz),
2
4.17 d (4H, H1, JHH = 14.3 Hz), 4.27 s (4H, H11), 6.81
3
3
s (2H, H4), 7.13 d. d (2H, H9, JH3H2 = 7.8, JH2H1 =
4.8 Hz), 7.60 d (2Н, H10, JH3H2 = 7.6 Hz), 8.40 d. d
3
(2H, H8, JH2H1 = 4.8, JH4H1 = 1.7 Hz), 8.50 d (2H, H7,
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4
4JH4H1 = 1.6 Hz). C NMR spectrum(CDCl3), δС, ppm:
13
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20.86 (Me5), 23.90 (Me3), 54.65 (C1), 59.88 (C11),
123.45 (C9), 129.62 (C4), 133.85 (C2), 136.91 (C10),
139.3 (C3), 143.93 (C2, C6), 148.64 (C8), 150.30 (C7).
31P NMR spectrum (DMF): δP –78.14 ppm. Found, %:
C 71.64; H 8.14; N 9.83; P 11.02. C30H40N4P2.
Calculated, %: C 71.83; H 7.39; N 9.86; P 10.91.
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This work was partially financially supported by
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