Synthesis and characterization of some phosphazenium chloride salts, [R3PNH2]+Cl- (R = phenyl, p-chlorophenyl and morpholino)

Article abstract of DOI:10.1080/15533174.2010.538025

Some phosphazenium chloride salts of the type [R₃PNH ₂]+Cl^-, where R = phenyl, p-chlorophenyl and morpholino, were synthesized by the reaction of the corresponding phosphiniminocyclotrithiazene compounds (R₃PNS<

Full text of DOI:10.1080/15533174.2010.538025

Synthesis and Reactivity in Inorganic, Metal-Organic, and Nano-Metal Chemistry, 41:147–149, 2011
Copyright © Taylor & Francis Group, LLC
ISSN: 1553-3174 print / 1553-3182 online
DOI: 10.1080/15533174.2010.538025
Synthesis and Characterization of Some Phosphazenium
+
2
−
Chloride Salts, [R PNH ] Cl (R = phenyl, p-chlorophenyl
3
and morpholino)
Akella Sivaramakrishna1,2 and M. N. Sudheendra Rao1
1
Department of Chemistry, Indian Institute of Technology Madras, Chennai, Tamilnadu, India
Chemistry Division, School of Advanced Sciences, VIT University, Vellore, Tamilnadu, India
2
the authors report the synthesis of these title compounds of the
+
−
+
−
Some phosphazenium chloride salts of the type [R
3
PNH
2
] Cl , type [R3PNH2] Cl , where R = phenyl, p-chlorophenyl and
where R = phenyl, p-chlorophenyl and morpholino, were morpholino (Eq. 1) from the reaction of the corresponding phos-
synthesized by the reaction of the corresponding phosphiniminocy-
clotrithiazene compounds (R PNS N ) with diphenyldichlorosi-
3 3 3
lane in acetonitrile. All the products were characterized by
analytical and spectroscopic data. The single crystal X-ray
] Cl was reinvestigated with one mole of
water molecule in the crystal lattice, showing an intermolecular
hydrogen bonding.
phiniminocyclotrithiazene compounds with diphenyldichlorosi-
lane in acetonitrile.
N
N
S
S
+
−
structure of [Ph
3
PNH
2
+
-
other
products
Ph2SiCl2, wet CH3CN
R3P=NH2 .Cl
+
R3P=N
S
N
4, R = Ph
, R = p-chlorophenyl
, R = OC4H8N-
5
6
1
2
3
, R = Ph
, R = p-chlorophenyl
Keywords crystal structure, hydrolysis, intermolecular hydrogen
bonding, phosphazenium chloride, phosphinimino-
cyclotrithiazenes
, R = OC4H8N-
INTRODUCTION
EXPERIMENTAL
Triphenylphosphazenium chloride and its derivatives have
been used in organic synthesis and catalysis.[
1−3]
They are also Apparatus
Spectra for H, 13C, and 31P NMR were collected on a Jeol
1
good ligands, can coordinate with various metal ions, and some
of these complexes have some important material properties.[
4]
JNM GSX 400 (160 MHZ) NMR spectrometer (chemical shifts
The preparation of triphenylphosphazenium chloride was re- are reported in parts per million relative to external Me Si as
4
−1
ported from the reaction between (NSCl)3 and RuCl2(PPh3)3 reference). Infrared spectra (4000–400 cm ) were recorded as
[5]
initially by Hursthouse and co-workers. It has also been pre- Nujol mulls (NaCl windows) on a Shimadzu 470 spectropho-
pared by the cleavage of the Nb-N bond of the phosphaneiminato tometer. Heraeus CHN rapid micro analyzer was used for ele-
moiety in [NbCl4(NPPh3)]2 complex in the presence of excess mental analysis. Melting points were determined with an appa-
NaF and 15-crown-5 in boiling acetonitrile[6] and by the reac- ratus using samples in one side sealed capillaries.
tion of Ph3P with Me3SiN3 in CH2Cl2-H2O mixture.[ These
7]
aspects prompted us to explore an alternative route for the prepa-
Materials
ration of three different phosphazenium chloride salts, and the
All chemicals were of reagent grade quality obtained from
possibility of substituent variation on phosphorus render them
commercial sources and used without further purification. The
as interesting examples for further studies. In the present work,
compound 1–3 were prepared by literature methods.[ Ph2SiCl2
8]
(0.173 g, 0.683 mmol) was added to a solution containing 1
(
0.282 g, 0.682 mmol) in CH3CN (20 mL) and after stirring
Received 21 May 2010; accepted 29 July 2010.
The authors are grateful to the Department of Science and Technol- the reaction mixture at room temperature. Then the solution
ogy, India for their financial support, and the Regional Sophisticated was decanted and the slow evaporation of solvent led to the
Instrumentation Centre, IIT-Bombay for the provision of the X-ray
isolation of the title compound (4) as colorless crystals (0.168
g, 75%), an orange crystalline solid, S4N4 (88 mg), and some
other unidentified products. In a similar way, 1 was reacted with
an aqueous solution of HCl (1:1, 10 mL) in 20 mL of CH CN.
diffractometer.
Address correspondence to Akella Sivaramakrishna, Department of
Chemistry, Indian Institute of Technology Madras, Chennai-630 036,
Tamilnadu, India. E-mail: asrkrishna@rediffmail.com
3
147

148
A. SIVARAMAKRISHNA AND M. N. S. RAO
TABLE 1
Summary of crystallographic results
Compound
4
Empirical formula
Formula weight
Temperature
C18H20ClNOP
332.77
293(2) K
0.70930 A
Wavelength
Crystal system, space group
Monoclinic, Cc
ꢀ
◦
˚
Unit cell dimensions
a = 16.2740(15) A, α = 90.000(6)
ꢀ
◦
˚
b = 10.6360(8) A, β = 99.144(7)
ꢀ
◦
˚
c = 10.3170(8), A, γ = 90.000(7)
ꢀ
3
˚
Volume
1763.1 (3) A
Z
4
−
1
3
Calculated density
Absorption coefficient
F(000)
1.254 Mg/cm
0.308 mm
700
−
Crystal size
θ range for data collection
Index ranges
0.40 × 0.40 × 0.30 mm
2.29 to 24.91 deg.
−19 ≤ h ≤ 0, 0 ≤ k ≤ 12, −12 ≤ l ≤ 12
Reflections collected/unique
Refinement method
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I ≥ 2σ(I)]
R indices (all data)
Absolute structure parameter
Largest diff. peak and hole
CCDC No.
1558/1558 [R(int) = 0.0000]
2
Full-matrix least-squares on F
1558/0/275
1.119
R1 = 0.0293, wR2 = 0.0681
R1 = 0.0337, wR2 = 0.0730
0.45(8)
−3
0.156 and −0.157 e.nm
774441
ꢀ
Preparation of [(p-chlorophenyl)3PNH2]Cl (5)
A similar procedure was followed by the reaction of 2 (0.206
g, 0.398 mmol) with Ph2SiCl2 (0.11 g, 0.438 mmol) in CH3CN
˚
radiation (k = 0.71073 A) in the φ-ω scan model at 294(2) K.
8
179 reflections were collected in the range of 1.88\h\26.41,
of which 2602 were independent. Intensity data were corrected
using the multi-scan method. Semi-empirical absorption correc-
◦
(
15 mL) to isolate 5. Yield 103 mg (64%). m. p. 122–126 C;
H–NMR (CDCl3): δ 7.18–7.92 (m, 12H, Ph), δ 1.55 (br, 2H,
1
[9]
tions were applied using the SADABS program. The struc-
tures were solved by direct methods and refined by full matrix
least-squares methods based on F with anisotropic thermal
parameters for all nonhydrogen atoms. Hydrogen atoms were
placed in their calculated positions, assigned fixed isotropic ther-
13
31
-
NH); C–NMR: δ 124.0, 125.0, 130.0, 132.6 and 134.0; P–
NMR: δ 34.6. Anal. calcd. for C18H14PNCl4 :C, 51.83; H, 3.38;
N, 3.36; Found, C, 51.26; H, 4.42; N, 4.02.
2
Preparation of [(morpholino)3PNH2]Cl (6)
A similar procedure was followed by the reaction of 3 (0.225 mal parameters, and allowed to ride on their respective parent
g, 0.509 mmol) with Ph2SiCl2 (0.141 g, 0.56 mmol) in CH3CN atoms. All computations were carried out using SHELXL-97
◦
[9]
(
15 mL) to obtain 6. Yield 138 mg (79%). m. p. 116–120 C; programs. A summary of the crystallographic data and details
1
H-NMR (CDCl3, 295 K): δ 3.10 (s, 12H, N-CH2), 3.72 (s, 12H, of the structure refinements are listed in Table 1.
13
O-CH2); δ 1.56 (br, 2H, -NH) C-NMR: δ 44.2 (N-CH2), 66.4
O-CH2); P-NMR: δ 33.5; Anal. calcd. for C12H26ClN4O3P:
C, 42.29; H, 7.69; N, 16.44; Found, C, 42. 53; H, 8.22; N, 16.23.
The compounds 4–6 can also be prepared in varying yields
by the reaction of 1–3 with aq. HCl in CH3CN solution.
31
(
RESULTS AND DISCUSSION
The title compounds (4–6) were isolated from the reaction
mixture of R3PNS3N3 (1–3) and Ph2SiCl2 in a wet acetonitrile
solution on exposure to air.[ This is probably due to the break-
ing of the exo-S-N bond in the presence of hydrated Ph2SiCl2
to form the R3PNH2 salt, and the involvement of water can also
be seen in the crystal lattice (see Figure 1).
9]
Crystal Structure Determination
X-ray data for 1 were collected on a Nonius 2000 CCD
diffractometer equipped with graphite-monochromated Mo Kα

SYNTHESIS OF SOME PHOSPHAZENIUM CHLORIDE SALTS
149
ꢀ
ꢀ
˚
˚
The O-H(1) (1.36(14) A) and O-H(2) (1.07(7) A) bonds in the
water molecule are surprisingly different. Though the P-N-C
and C-P-C bond angles in 4 are comparable with the literature
◦
◦
values, the P-N-H (121(3) ) and H-N-H (117(4) ) bond angles
slightly longer. These differences may indicate that the variance
in the structural features due to the presence of water molecule
showing a significant hydrogen bonding.
REFERENCES
1
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drogen bonding. The aromatic hydrogen atoms are not shown for clarity.
4
370.
1H NMR showed the presence of phenyl proton signals
4
5
6
. a) Courtenay, S.; Wei, P.; Stephan, D.W. The syntheses and structures of
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actions of phosphaneiminato complexes of niobium, molybdenum, and
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PPh F . Zeit. Anorg. Allg. Chem. 1991, 602, 7–16.
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as a multiplet at δ 6.96–7.94 and δ 7.18–7.92 for 4 and 5,
31
respectively. P NMR indicated a singlet for 4 at δ 35.5 and
for 5 at δ 34.6. In IR, it was observed that the bands for vNH
−
1
−1
.
at 3100 cm and a very strong band for vP=N at 972 cm
The spectroscopic and analytical data obtained for 4 is in good
agreement with the earlier reports. The other compounds 5
[5]
−1
and 6 also showed IR bands for vP=N at 980 and 985 cm , re-
1
13
spectively. H-NMR and C-NMR spectra of 6 showed the re-
spective morpholine signals at 3.12 (N-CH2), 3.74 (O-CH2), and
δ 43.1 (N-CH2), 66.2 (O-CH2), respectively. 31P-NMR showed
a singlet at δ 33.5. All the spectral data is consistent with their
3
2
[10]
analogous phosphazenium iodide salts.
+
−
Figure 1 shows the molecular structure of 4, associated with
one mole of H2O per each Ph3PNH2Cl. The molecule exists
as an ionic compound and it has a slightly irregular tetrahe-
dral geometry around the P-atom with a relatively short P-N
8
. a) Krauss, B.; Jung, H. Z. Naturforsch. 1961, 16B, 624; b) Swarnalatha,
U.; Sivaramakrishna, A.; Venkatachalam, C.S.; Rao, M.N.S.; Inoue, N.;
Ueda, T.; Hojo, M. Studies on electrochemical and coordination be-
haviour of phosphiniminocyclotrithiazenes. Can J. Chem 2002, 80, 1428–
◦
bond (1.607(4) A). Dimeric units are formed through the in-
1
434.
termolecular hydrogen bonds of O–H. . . . . Cl and N-H. . . . . Cl.
By comparing the most striking structural features of 4 with the
literature reports, the differences in some of the bond angles
9
. a) Sheldrick, G.M. SADABS, Program for Empirical Absorption Correc-
tion of Area Detector Data; University of G o¨ ttingen: Germany, 1996. b)
Sheldrick, G.M. SHELXS 97 and SHELXL 97; University of G o¨ ttingen:
Germany, 1997.
10. Sivaramakrishna, A.; Rao, M.N.S. Studies on iodination reactions of phop-
shiniminocyclotrithiazenes. (Unpublished results.)
11. Pohl, E.; Gogine, H.J.; Herbst-Irmer, R.; Noltemeyer, M.; Roesky, H.W.;
Sheldrick, G.M. Structures of amino(triphenyl)phosphonium bromide and
amino(triphenyl)phosphonium hexachloroantimonate. Acta Cryst. 1993,
C49, 1280–1283.
and bond lengths are shown. The P-N and P-C bond lengths in
ꢀ
[7]
˚
4
are almost identical to the literature values (1.607(4) Aand
ꢀ
ꢀ
˚
˚
1
.784(3) –1.800(4) A, respectively). The N-H(1) (0.79(5)A) and
ꢀ
˚
N-H(2) (0.74(4) A) bond distances in 4 are comparatively short
ꢀ
[11]
˚
with the reported phosphazenium cations, i.e., 0.84 (22) A.

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