New results in the ammonolysis of hexafluoro-cyclo-triphosphazene: Crystal structure of P3N3F5-NH-P3 N3F4NH2

Article abstract of DOI:10.1016/j.poly.2009.06.083

The reaction of hexafluoro-cyclo-triphosphazene P₃N₃F₆ with ammonia in acetonitrile has been studied. New compounds, (2-imino-2,4,4,6,6-pentafluoro-2λ⁵,4λ ⁵,6λ⁵-cyclo-triphosphaza-1,3,5-tri

Full text of DOI:10.1016/j.poly.2009.06.083

Polyhedron 28 (2009) 3078–3086
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New results in the ammonolysis of hexafluoro-cyclo-triphosphazene: Crystal
structure of P3N3F5–NH–P3N3F4NH2
a
a
b,c
a
V. Richterová a, M. Alberti b,c, , J. Príhoda , P. Kubácek , J. Taraba , Z. Zák
*
ˇ
ˇ
ˇ
a
ˇ
Department of Chemistry, Faculty of Science, Masaryk University, Kotlárská 2, CZ-61137 Brno, Czech Republic
Department of Physical Electronics, Faculty of Science, Masaryk University, Kotlárská 2, CZ-61137 Brno, Czech Republic
Episcopical Gymnasium, Barvicova 85, 602 00 Brno, Czech Republic
b
c
ˇ
ˇ
a r t i c l e i n f o
a b s t r a c t
Article history:
The reaction of hexafluoro-cyclo-triphosphazene P3N3F6 with ammonia in acetonitrile has been studied.
New compounds, (2-imino-2,4,4,6,6-pentafluoro-2k5,4k5,6k5-cyclo-triphosphaza-1,3,5-trienyl)-2-amino-
4,4,6,6-tetrafluoro-2k5,4k5,6k5-cyclo-triphosphaza-1,3,5-triene, P3N3F5–NH–P3N3F4NH2 (2) and cis and
trans isomers of non-gem-2,4-diamino-2,4,6,6-tetrafluoro-2k5,4k5,6k5-cyclo-triphosphaza-1,3,5-triene,
P3N3F4(NH2)2 (4, 5), were detected by GC/MS, and 31P NMR spectroscopy in reaction mixtures. X-ray dif-
fraction analysis of P3N3F5–NH–P3N3F4NH2 (2) revealed two conformational polymorphs, 2A and 2B, the
latter being built up of two different conformers that were further denoted as 2Ba (the same as the single
conformer in 2A) and 2Bb. The compound 2 was characterized by spectroscopic methods and its 2D
potential energy surface (PES) was described by density functional theory computations depending on
two dihedral angles. The calculated PES spans over 30 kJ/mol in energy including 8 local minima and
all first and second order saddle points. The occurrence of the two experimentally observed conformers
2Ba and 2Bb seems to be governed by crystal packing effects.
Received 25 March 2009
Accepted 19 June 2009
Available online 5 July 2009
Keywords:
(2-Imino-2,4,4,6,6-pentafluoro-2k5,4k5,6k5-
cyclo-triphosphaza-1,3,5-trienyl)-2-amino-
4,4,6,6-tetrafluoro-2k5,4k5,6k5-
cyclotriphosphaza-1,3,5-triene
Crystal structure
Fluorophosphazene
DFT
Conformational polymorphism
Ó 2009 Published by Elsevier Ltd.
1. Introduction
The fact that significantly fewer studies on the chemistry of
hexafluoro-cyclo-triphosphazene have been published is probably
Substituted phosphazenes are supposed to be perspective sub-
stances that can be utilized in many fields of human activities,
e.g. as pesticides [1], chemosterilants [2,3], cytostatic agents [4,5]
or antioxidants [6,7]. Some of them can serve as monomer units
for preparations of polymers having useful properties and applica-
tion, e.g. as fire retardants [8], thermally stable macromolecules
[9,10], biomaterials [11–14], membranes [15], hybrid materials
[16,17], ceramics [18,19]. In most cases their syntheses start from
hexachloro-cyclo-triphosphazene, P3N3Cl6. Gleria et al. highlighted
the synthesis, characterization, and practical exploitation of differ-
ent types of polyphosphazenes substituted with fluorinated
groups. There are several ways in which fluorine atoms can be in-
serted into polyphosphazenes, all of which leading to different
polymers showing a wide range of characteristics. In general inser-
tion of fluorine atoms into phosphazene macromolecules leads to
enhancement of the thermal stability, flame resistance, low-tem-
perature elastomericity, and chemical inertness of the phosphaz-
enes obtained [20].
due to its somewhat difficult synthesis, physico-chemical proper-
ties (considerable volatility, specific reactivity resulting from un-
ique electronic structure) and extensive requirements on the
measuring instruments necessary for the determination of the
molecular structure of the reaction products, composition of reac-
tion mixtures and kinetic studies [21,22].
The reactions of hexafluoro-cyclo-triphosphazene with sodium
phenoxide was described by Freund et al. [23]. They found that
the reaction led to the phenoxyfluorocyclotriphosphazenes
P3N3(OPh)nF6ꢀn. Synthesis and ansa substitution of novel examples
of aryl hydrido fluorophosphazenes was described by Elias and
Muralidharan [24].
Chemistry of fluorinated cyclophosphazenes differs consider-
ably from that of their chlorinated analogues in that fluorophos-
phazene compounds are in general more volatile and stable
[25–27]. On the other hand, polymer (NPF2)n itself is very sensitive
to hydrolysis as compared to the precursor hexafluoro-cyclo-tri-
phosphazene [28].
Therefore a study of substitution reactions of P3N3F6 may be sig-
nificant. Although the reactivity of the cyclic phosphazene P3N3Cl6
is well known, the reactions of P3N3F6 proceed differently in most
cases. For instance, it is possible to prepare mono- to hexasubsti-
tuted aminoderivatives of P3N3Cl6 by reactions of P3N3Cl6 with pri-
mary and secondary amines [29] while only monosubstituted
* Corresponding author. Address: Department of Physical Electronics, Faculty of
ˇ
Science, Masaryk University, Kotlárská 2, CZ-61137 Brno, Czech Republic. Tel.: +420
549495026.
E-mail address: alberti@chemi.muni.cz (M. Alberti).
0277-5387/$ - see front matter Ó 2009 Published by Elsevier Ltd.
doi:10.1016/j.poly.2009.06.083

V. Richterová et al. / Polyhedron 28 (2009) 3078–3086
3079
Derivative
Product
*
Structural formula
and compound
number
F
F
F
F
NH2
P
N
N
F
P
N
N
P
N
P
N
P
NH
F
P
F
N
P
F
F
P
N
P
N
F
F
H2N
1:1
F
F
F
F
1
2
(bridged derivative)
H2N NH2
P
F
NH2
H2N
P
P
N
P
N
P
N
P
N
P
N
P
N
P
F
F
F
F
F
NH2
N
N
N
F
F
F
NH2
F
F
3
4
5
(geminal)
(nongeminal cis-)
(R,S nongeminal trans-)
NH2
NH2
F
F
1:2
P
N
P
N
NH2
F
N
P
N
P
NH
NH
NH2
F
P
F
N
P
N
N
P
N
P
F
F
P
N
P
N
F
P
N
P
F
H2N
F
NH2
N
F
F
F
F
6
7
(some bridged derivatives)
Scheme 1. Possible products in the reaction of P3N3F6 with ammonia (1:8).
derivatives were isolated from a direct reaction of P3N3F6 with var-
ious amines [30–33]. Geminal disubstituted P3N3F4(NMe2)2 was
described by Chivers et al. [32]. Nevertheless, the authors eluci-
dated its formation from geminal P3N3F4Cl2 whose residues were
found in the starting P3N3F6. Fluorination of aminochlorophosp-
hazenes by SbF3 or KSO2F [34–36] is the most common way used
for the preparation of multiple-substituted aminoderivatives of
hexafluoro-cyclo-triphosphazene.
It is known that the reaction of P3N3Cl6 with gaseous ammonia
in diethylether leads to the formation of disubstituted derivative
P3N3Cl4(NH2)2 [37–39]. Monosubstituted aminoderivative P3N3Cl5NH2
can be prepared by adding dry gaseous HCl to the solution of
P3N3Cl4(NH2)2 inacetonitrile[40]orindioxane[41]. Onthecontrary,
ammonolysis of P3N3F6 carried out in diethylether at ꢀ25 °C yielded
monosubstituted P3N3F5NH2 as the main product [42]. Geminal
disubstituted derivative P3N3F4(NH2)2 was prepared by fluorination
of the corresponding chlorophosphazene P3N3Cl4(NH2)2 by CsF in
acetonitrile [43]. Structure of P3N3F4(NH2)2 was determined by
X-ray analysis [44], elemental analysis, melting point and mass
spectrum can be found in [43].
Direct syntheses of higher-substituted amino fluorophosphaz-
enes from P3N3F6 and ammonia, have not been described yet.
The only information available can be found in [45] where the
behavior of P3N3F6 and ammonia in various solvents at increasing
molar ratio of starting compounds up to 1:24 was studied. The
reaction mixtures, even after long reaction times, were found to
be very complex and no effective way to separate individual reac-
tion products was found. Mass spectrometry proved the presence
of at most trisubstituted aminoderivatives of P3N3F6 and dimer
compounds while in the case of reaction between hexachloro-cy-
clo-triphosphazene with excess ammonia it was possible to pre-
pare fully substituted aminoderivative [46,47].
Therefore our effort to elucidate the reaction system P3N3F6 and
ammonia was concentrated on finding such reaction conditions
(molar ratio of starting compounds, solvent, reaction time) that
would enable to prepare also higher-substituted aminoderivatives
of P3N3F6. Molar ratio of starting compounds of 1:8 was chosen for
our studies. In this case at most tetrasubstituted aminoderivatives
of P3N3F6 can be expected (4 NH3 molecules are used for substitu-
tion, 4 NH3 molecules serve as acceptor of released HF). There are

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V. Richterová et al. / Polyhedron 28 (2009) 3078–3086
H2N NH2
P
H2N
F
H2N
F
P
P
N
P
N
P
N
P
N
P
N
P
N
P
F
F
F
F
H2N
NH2
N
N
N
1:3
F
NH2
H2N
NH2
F
F
8
9
10
(R,S geminal)
(nongeminal cis-)
(nongeminal trans-)
F
F
P
N
N
NH2
NH
N
P
e.g. 11 (geminal, bridge)
F
P
F
2:3
N
P
F
P
N
P
N
F
H2N
F
F
H2N NH2
P
H2N NH2
P
H2N NH2
P
N
P
N
P
N
P
N
P
N
P
N
P
F
NH2
NH2
F
F
F
NH2
N
N
N
F
H2N
NH2
H2N
F
12
13
14
(geminal)
(nongeminal cis-) (R,S nongeminal trans-)
NH2
NH2
F
1:4
F
P
N
P
N
NH2
F
N
P
N
P
NH
NH
NH2
P NH2
F
P
F
N
P
N
H2N
N
P
N
P
F
P
N
P
P
N
H2N
F
NH2
NH2
N
N
NH2
H2N
H2N
F
15
(some bridged derivatives)
16
* number of phosphazene rings : number of amino (imino, respectively) groups
Scheme 1. (continued)
many possibilities how to combine reaction products, some of
them are summarized in Scheme 1.
Results of our investigations of the reaction system P3N3F6/
ammonia/solvent are summarized in this article.
Solvents – 1,1,2,2-tetrachlorethane, diethylether (Penta Chru-
dim, CZ), and acetonitrile (Lach-Ner s. r. o. Neratovice, CZ) were
of reagent grade purity and dried by methods described in Perrin
and Armarego [49].
2. Experimental
2.2. Instrumentation
2.1. Reagents and general procedures
Elemental analysis was performed after mineralization of a
sample with sodium peroxide in Parr bomb. The content of phos-
phorus was determined gravimetrically by precipitation with quin-
oline [50]. The content of fluorine was obtained from the difference
between masses of the sample before and after fuming off SiF4 (in
the presence of sulfuric acid and silica sand). The content of nitro-
gen was determined by Kjeldahl method.
P3N3F6 was prepared by fluorination of P3N3Cl6 with NaF in ace-
tonitrile [48]. The solvent was distilled off and a crude semi-solid
product was obtained. Anhydrous MgSO4 was added with the
aim to remove last traces of water. Then, P3N3F6, due to its volatil-
ity, was distilled off in vacuum from this mixture.
Liquid ammonia (Chemopetrol Litvínov a.s., CZ) was prepared by
condensation from gaseous ammonia that was dried by passing it
through a column filled with KOH (Lachema Brno, CZ) and metallic
sodium wire (Ferak Berlin, BRD).
All operations were performed under dry gaseous nitrogen
using conventional Schlenk techniques and vacuum lines.
The IR spectra were recorded in nujol and Kel-F mulls using a FTIR
Bruker 28 spectrometer (measuring range 4000–400 cmꢀ1, resolu-
tion 2 cmꢀ1). Measurements were performed in demountable KBr
cell. Raman spectra of solid samples in original Raman capillaries
were measured on Bruker IFS55 Equinox apparatus, with Raman
adapter FRA106/S (laser k = 1064 nm, W = 150–400 mW) equipped.

V. Richterová et al. / Polyhedron 28 (2009) 3078–3086
3081
Table 1
The compounds and their content determined by GC (in %).a
Retention time (min)
M+ (found/calculated)
Compound
Filtrate
S1
S2
S3
160 °C + 6 h
65 °C + 6 h
80°C + 6 h
5.8
9.4
10.5
10.9
12.3
246/245.965
243/242.962
243/242.962
243/242.962
472/471.896
P3N3F5NH2 (1)
gemP3N3F4(NH2)2 (3)
new cis and trans non-gem P3N3F4(NH2)2 (4, 5)
1
0
20
5
5
0
0
0
10
10
4
0
0
5
5
20
20
20
39
new compound (2)
35
a
The content of components is related to their content in filtrate.
The 31P NMR spectra were measured using FT NMR spectrome-
ter Bruker Avance DRX 500 (frequency 202.404 MHz). Spectra were
referred to 85% H3PO4. The samples were filled in the SimaxÒ tubes
(external diameter 4 mm). These tubes were inserted into original
cuvettes WilmadÒ (external diameter 5 mm) filled by D2O that was
used as the deuterium lock.
Mass spectra (EI) were measured by a spectrometer Finnigan
MAT Trio 1000, series II, connected to a gas chromatograph GC
8000 and column DB-5. Excitation energy was 70 eV and 1–2 ll
This sublimation product was recrystallized from 1,1,2,2-tetra-
chloroethane. The substance 2 was isolated in the form of two
polymorphs 2A or 2B.
The yield of the compound 2 was 35%, as related to P3N3F6. Its
melting point was determined from microcrystalline material to
be 186 °C. The crystals of 2 for X-ray diffraction were grown from
1,1,2,2-tetrachloroethane.
Elemental analysis of 2: found/calc. (%): P – 38.13/39.37, F –
35.78/36.23, N – 23.51/23.75.
of liquid samples were sprayed into the column. The temperature
of the heating zone was 50–280 °C and the rate of temperature rise
was 10 or 15 °C minꢀ1. Nitrogen was used as carrier gas (flow
1.8 cm3 minꢀ1).
The melting points were determined using electric Boethius
apparatus Nagema PHMK 05. The samples were sealed in a glass
capillary.
Mass spectrum of 2: M+ = 472 (P6N6F9N2H3+), 457 (P6N6F9NH2+),
456 (P6N6F9NH+), 453 (P6N6F8N2H3+), 438 (P6N6F8NH2+), 436
(P6N6F8N+), 433 (P6N6F7N2H2+), 423 (P6N6F8H+), 397 (P6N6F6N+),
353 (P5N5F6N+), 245 (P3N3F5NH+), 230 (P3N3F5+), 227 (P3N3F4NH2+),
212 (P3N3F4H+), 211 (P3N3F4+), 209 (P3N3F3NH2+), 197 (P3N2F4+),
166 (P2N2F4+), 152 (P2NF4+), 148 (P2N2F3H+), 129 (P2N2F2H+), 128
(P2N2F2+), 114 (P2NF2+), 107 (PF4+), 88 (PF3+), 69 (PF2+), 50 (PF+),
46 (PNH+).
The structures of the compounds were determined using a
KUMA KM-4 CCD
j
-axis diffractometer with a graphite monochro-
Raman spectrum of 2A: 211 vw, 259 vw, 289 w, 292 w, 297 w,
300 vw, 317 vw, 355 vw, 399 vw, 407 vw, 463 vw, 474 vw, 526
vw, 538 vw, 550 sh, 554 w, 600 vw, 736 vs, 782 vw, 948 vw,
1545 vw, 2712 vw, 3043 bvw, 3273 vw.
matized Mo K radiation (k = 0.71069 Å). The structure was solved
a
through direct methods. Non-hydrogen atoms were refined aniso-
tropically while hydrogen atoms were inserted in calculated posi-
tions and isotropically refined assuming a ‘‘ride-on” model. SHELX
-
Raman spectrum of 2B: 211 vw, 260 vw, 288 w, 293 w, 295 w,
302 vw, 317 vw, 335 vw, 368 vw, 445 vw, 463 vw, 474 vw, 526
vw, 537 w, 550 w, 555 vw, 601 vw, 737 vs, 792 vw, 854 vw, 945
vw, 1546 vw, 2714 vw, 2992 bvw, 3270 vw.
97 program package [51] was used for the structure determina-
tions; the drawings were made by XP program of Bruker SHELXTL
V5.1 program package [52].
Infrared spectrum of 2A: 409 vw, 430 vw, 445 w, 463 m, 446 s,
485 m, 505 s, 509 sh, 527 vw, 537 vw, 560 vw, 569 vw, 596 vw,
723 vw, 738 vw, 792 w, 809 s, 817 s, 826 vs, 842 vs, 861 sh, 888
m, 898 sh, 937 sh, 949 vs, 962 sh, 1009 m, 1040 m, 1180 vw,
1196 vw, 1252 sh, 1279 vs, 1371 m, 1544 vw, 1559 vw, 2714 vw,
3080 bvw, 3282 vw, 3302 vw, 3423 w, 3444 vw.
Infrared spectrum of 2B: 411 vw, 432 vw, 445 s, 486 m, 506 s,
528 vw, 538 vw, 560 vw, 570 vw, 595 vw, 723 vw, 738 vw, 791
w, 816 s, 826 vs, 840 vs, 864 sh, 887 m, 935 sh, 947 vs, 962sh,
1002 vw, 1012 m, 1041 m, 1180 vw, 1200 vw, 1218 vw, 1235
vw, 1245 sh, 1269 vw, 1278 vs, 1372 m, 1543 vw, 1559 vw, 2714
vw, 3081 bvw, 3280 vw, 3297 vw, 3423 w, 3442 vw.
2.3. Quantum chemical calculations
The quantum chemical calculations were carried out with the
molecular ADF program, version 2007.01 [53–55].
In the ADF calculation of the two-dimensional conformational
PES two dihedral angles were changed in steps of 20°, all other nu-
clear coordinates being optimized, and DZP basis set, middle frozen
core, integration accuracy to 4 digits, and LDA (VWN) functional
was used. Molecular geometries for the two local minima closest
to the by X-ray diffraction determined conformers were optimized
with QZ4P basis set, no frozen core, integration accuracy to 6 digits,
and OPBE [56] functional that combines OPTX (exchange) [57] and
PBEc (correlation) [58]. The calculations of the IR spectra were car-
ried out at the same level with no scaling factor.
2.5. Identification of other reaction products
Mass spectrum of P3N3F5NH2 (1): M+ = 246 (P3N3F5NH2+), 230
(P3N3F5+), 227 (P3N3F4NH2+), 216 (P3N2F5+), 212 (P3N3F4H+), 207
(P3N3F3NH+), 197 (P3N2F4+), 171 (P2NF5+), 167 (P2N2F4H+), 152
(P2NF4+), 133 (P2NF3+), 129 (P2N2F2H+), 114 (P2NF2+), 107 (PF4+),
104 (PNF3H2+), 88 (PF3+), 84 (PNF2H+), 81 (P2F+), 69 (PF2+), 66
(PNFH2+), 50 (PF+), 46 (PNH+).
2.4. Synthesis of P3N3F5–NH–P3N3F4NH2 (2)
Ammonolysis of P3N3F6 with liquid ammonia was carried out at
a molar ratio of 1:8. Amount 2.489 g (10 mmol) of P3N3F6 was
placed into 30 cm3 of acetonitrile in a sealed Schlenk tube con-
nected to a vacuum line and 1.32 g (80 mmol) of ammonia was
added by condensation of gaseous ammonia. The mixture was kept
at 20 °C for 24 h. Precipitated NH4F was filtered off by a Schlenk frit
(porosity S4).
The solvent was removed from the filtrate by means of vacuum
distillation (oil pump). A white solid, crude 2, was obtained and
purified by vacuum sublimation (2 Pa, 80 °C, 6 h).
Mass spectrum of P3N3F4(NH2)2
(3, 4, 5)1
:
M+ = 243
(P3N3F4(NH2)2+), 227 (P3N3F4NH2+), 224 (P3N3F3(NH2)2+), 212
(P3N3F4H+), 207 (P3N3F3NH+), 198 (P3N2F4H+), 197 (P3N2F4+), 194
(P3N3F3H2+), 192 (P3N3F3+), 182 (P2N3F4H2+), 178 (P3N2F3+), 168
(P2N2F4H2+), 167 (P2N2F4H+), 166 (P2N2F4+), 164 (P3NF3+), 152
1
All mass spectra are identical, only intensities of fragments are rather different.

3082
V. Richterová et al. / Polyhedron 28 (2009) 3078–3086
Fig. 1. The molecular structure of 2A. Thermal ellipsoids are drawn with 50%
Fig. 4. The best fit of 2A and 2Ba molecules.
probability.
31P NMR spectrum of 3: P(NH2)2 triplet at d = 19.7 ppm and split
PF2 triplet at d = 11.9 ppm; 31P NMR spectrum of 4, 5: PFNH2 dublet
of broad signals at d = 25.1 ppm and split PF2 triplet at
d = 10.6 ppm.
3. Results and discussion
Ammonolysis of P3N3F6 was studied by simple mixing of the
substrate (P3N3F6) with liquid ammonia in a Schlenk tube in aceto-
nitrile. The molar ratio of reactants was kept at 1:8, the reaction
was carried out at 20 °C for 24 h. Solid NH4F was formed in the
course of the reaction and was filtered off. The solvent, together
with volatile P3N3F5NH2 (1), were evaporated from the filtrate
and 1 was identified by MS spectrometry. The residue in the form
of a white powder was obtained. Its purification was carried out by
vacuum sublimation at 2 Pa. Several fractions of a solid (S1, S2, S3)
were isolated in the course of vacuum sublimation. Fraction S1 was
obtained at 60 °C after 6 h, fraction S2 at 65 °C after another 6 h of
sublimation. Thus more volatile products 3, 4, 5 were removed
from the crude product. The sublimation at 80 °C for additional
6 h led to the isolation of an unknown compound 2.
The composition of the filtrate and sublimation fractions was
studied by NMR spectrometry and GC/MS (see Table 1).
Fig. 2. A part of a column of molecules in the structure of 2A showing hydrogen
bonds. Fluorine atoms are omitted for clarity. Symmetry code: #1 ꢀx + 1, ꢀy,
ꢀz + 1; #2 ꢀx + 2, ꢀy, ꢀz + 1.
It follows from Table 1 that the first sublimation fraction S1
contains mostly geminal P3N3F4(NH2)2 (3), fraction S2 has majority
of nongeminal cis or trans-P3N3F4(NH2)2 (4, 5) that have not been
described so far. The signals of 4, 5 were identified in 31P NMR
spectrum of the sublimation fraction S3 dissolved in acetonitrile.
Diamines P3N3F4(NH2)2, (3, 4, 5) were also identified by GC/MS.
The third sublimation fraction S3 contains mainly the substance
2. Recrystalization of 2 from 1,1,2,2-tetrachloromethane yielded
pure crystals suitable for X-ray analysis. X-ray diffraction experi-
ments showed that the substance 2 is the hitherto not described
dimeric phosphazene aminoderivative in which two phosphazene
cycles are connected via a NH-bridge.
F
F
F
P
N
N
F
F
Fig. 3. Perspective view of molecules 2Ba (left) and 2Bb (right) of the structure of
2B. Thermal ellipsoids are drawn with 30% probability.
F
N
P
N
N
P
NH
P
F
P
N
H2 N
(P2NF4+), 149 (P2N2F3H2+), 148 (P2N2F3H+), 133 (P2NF3+), 129
(P2N2F2H+), 128 (P2N2F2+), 114 (P2NF2+), 107 (PF4+), 104 (PNF3H2+),
95 (P2NF+), 88 (PF3+), 85 (PNF2H2+), 84 (PNF2H+), 81 (P2F+), 69
(PF2+), 66 (PNFH2+), 50 (PF+), 46 (PNH+).
F
P
F
F
2

V. Richterová et al. / Polyhedron 28 (2009) 3078–3086
3083
Two kinds of monoclinic crystals (polymorphs 2A, 2B) were ob-
tained by crystallization of the sublimation fraction S3 from
1,1,2,2-tetrachloroethane (see below).
If the ammonolysis of P3N3F6 was performed in diethylether the
NMR analysis of the reaction mixture showed that monoamine
P3N3F5NH2 (1) was present as the main product in the reaction
mixture (>95% yield). Other substitution products, geminal (3)
and cis and trans nongeminal isomers P3N3F4(NH2)2 (4, 5), and
new derivative (2) were present only in negligible amounts as
indentified by GC/MS.
3.1. X-ray structure analysis of 2
The crystals of polymorph 2A are monoclinic, space group P21/
n. The asymmetric unit contains one molecule of 2A in a general
position (Fig. 1). The angle between the best planes through both
P–N rings is 123.7(1)° with P1–N4–P4 bridging angle 128.6(1)°.
The P1–F1 bond of P1–N1–P2–N2–P3–N3 (ring R1) is fairly parallel
to the P4–N6–N7–P6–N8 ring (ring R2) and thus F1 and N5 are
mutually in trans position. Both P–N rings are slightly twisted
and thus deviating from exact planarity. The largest deviations of
N atoms from the planes defined by P atoms are 0.058(3) Å (R1,
N3) and 0.121(2) Å (R2, N8).
There are three possible hydrogen bond systems involving all
three hydrogen atoms which bind the molecules into parallel col-
umns: N4(H1)ꢁ ꢁ ꢁN8 (2.19 Å), N5(H2)ꢁ ꢁ ꢁN1 (2.67 Å), and
N5(H3)ꢁ ꢁ ꢁN6 (2.34 Å) (Fig. 2 and Table 5 upper part).
The structure of polymorph 2B is also monoclinic, space group
C2/c. The asymmetric unit contains two molecules (2Ba and 2Bb) in
general positions. However, contrary to the structure of 2A, the
molecules are two different conformers (Fig. 3).
3.1.1. 2Ba molecule
The molecule 2Ba is the same conformer as that in the poly-
morph 2A (Fig. 4).
Thus the angle between the best planes drawn through
P11–N11–P21–N21–P31–N31 (ring R11) and P41–N61–P51–
N71–P61–N81 (ring R21) is 132.5(1)° (123.7° in 1A) with
P11–N41–P41 bridging angle 129.4(1)° (128.6° in 2A). Deviation of
both rings from planarity is practically the same both in 2A and
2Ba. The largest deviations of N atoms from the best planes defined
by P atoms are 0.048(3) Å (R11, N21) and 0.148(3) Å (R21, N81).
Fig. 5. Parts of 2Ba (upper) and 2Bb (lower) molecular columns showing hydrogen
bonds in the structure of 2B. Fluorine atoms are omitted for clarity. Symmetry code:
#1 1 ꢀ x + 1/2, ꢀy + 1/2, ꢀz + 1; #2 ꢀx + 1/2, ꢀy + 3/2, ꢀz + 1; #3 ꢀx, ꢀy + 1, ꢀz, #4
ꢀx, ꢀy + 2, ꢀz.
3.1.2. 2Bb molecule
2Bb can be derived from 2Ba (or 2A) by rotating one P–N ring by
approx. 180° around the P–N(H) bond. As a result, F11 and N51(H)
are mutually in a cis position.
Thus the angle between the best planes drawn through P12–
N12–P22–N22–P32–N32 (ring R12) and P42–N62–P52–N72–
P62–N82 (ring R22) is 30.9(1)° and P12–N42–P42 bridging angle
124.2(2)° (128.6° in 1A, 129.4° in 2Ba. The largest deviations of N
atoms from the best planes defined by P atoms are 0.126(3) Å
(R12, N12) and 0.133(3) Å (R22, N82).
lengths are similar. However, P–N bonds in the P–N ring, which are
in the vicinity of P1, P4, or P7, P10 atoms, respectively, are some-
what longer (1.601–1.617 Å) as compared to published data
(1.582–1.597 Å) [44,59,60].
3.2. Quantum chemical calculations for 2
The crystal structure of 2B is built from alternating columns of
molecules propagating along the axis b, each column being com-
posed of the same conformer only (Fig. 5). Within each column
the molecules are connected by hydrogen bonds (Table 5, lower
part).
Crystal data and structure refinement for 2A and 2B are given in
Table 2, selected bond lengths in Table 3 and selected bond angles
in Table 4.
The agreement between the metrical parameters from X-ray
and from ADF calculation is very good except for the two sloppy
torsions around P–N bonds in the P–NH–P bridge. Selected metri-
cal parameters are shown in Table 6. The two-dimensional poten-
tial energy surface (PES) is in Fig. 6. It shows 8 minima with the
torsion angles given in Table 7. The calculated minima for the
gas phase molecules with the labels a and b in Fig. 6 and Table 7
differ in those dihedral angles by 6–12° from X-ray data. The con-
formational PES extends within 30 kJ/mol including apparent local
maxima, in fact saddle points of second order. All the 8 local
The comparison between bond parameters of 2A, 2B with ana-
logical data, e.g. for compounds 1, 3, shows that bond P–N and P–F

3084
V. Richterová et al. / Polyhedron 28 (2009) 3078–3086
Table 2
Crystal data and structure refinement for 2A and 2B.
Compound
2A
2B
Empirical formula
Formula weight
P6N8F9H3
471.92
120
P6N8F9H3
471.92
120
T (K)
0
0.71069
0.71069
Wavelength (ÅA)
Crystal system
Space group
monoclinic
P21/n
monoclinic
C2/c
Unit cell dimensions
0
7.4732(15)
21.965(4)
9.3845(19)
38.064(8)
7.3852(15)
22.165(4)
a (AÅ)
0
b (AÅ)
0
c (AÅ)
a
(°)
90
90
b (°)
107.76(3)
90
1467.1(5)
113.08(3)
90
5732(2)
c
(°)
0
V (AÅ3)
Z
4
16
2.187
0.860
3680
Calculated density (Mg mꢀ3
)
2.137
0.840
920
Absorption coefficient (mmꢀ1
F(0 0 0)
)
Crystal size (mm)
h range for data collection (°)
Limiting indices
Reflections collected/unique [Rint
Completeness to 2h = 25.00 (%)
Absorption correction
0.25 ꢂ 0.10 ꢂ 0.04
0.40 ꢂ 0.20 ꢂ 0.20
2.94–25.0
2.91–25
ꢀ7 6 h 6 8; ꢀ26 6 k 6 26; ꢀ11 6 l 6 11
10 023/2574 [0.0434]
99.7
ꢀ44 6 h 6 44; ꢀ8 6 k 6 6; ꢀ26 6 l 6 26
]
32 575/5038 [0.0392]
99.8
w
-scan
w-scan
Maximum and minimum transmission
Refinement method
0.9672 and 0.8174
full-matrix least-squares on F2
2574/0/211
0.8468 and 0.7247
full-matrix least-squares on F2
5038/0/421
Data/restrains/parameters
Goodness-of-fit (GOF) on F2
1.047
1.065
Final R indices [I > 2
R indices (all data)
Largest difference in peak and hole (e ÅAꢀ3
r
(I)]
R1 = 0.0310, wR2 = 0.0837
R1 = 0.0382, wR2 = 0.0877
0.420/ꢀ0.427
R1 = 0.0410, wR2 = 0.1004
R1 = 0.0474, wR2 = 0.1040
0.547/ꢀ0.565
0
)
P
P
P
2
2
2
wR2 ¼ f ½wðF2o ꢀ Fc2Þ ꢃ= ½wðF2oÞ ꢃg1=2, R1
=
R
||Fo| ꢀ |Fc||/
R
|Fo|, GOF ¼ S ¼ f ½wðF2o ꢀ Fc2Þ ꢃ=ðn ꢀ pÞg1=2, where n is the number of refections and p is the total number of
parameters refined.
rotation around exocyclic P–N bonds in 2 are very low, less than
15 kJ/mol, in the gas phase. This is in the agreement with the spe-
cial bonding pattern of the phosphazene rings (e.g. [22]) that
Table 3
Selected bond lengths (Å) for 2A and 2B.
2A
2Ba
2Bb
leaves those bonds with no p-contribution.
P(1)–F(1)
P(1)–N(1)
P(1)–N(3)
P(1)–N(4)
N(1)–P(2)
P(2)–F(3)
P(2)–F(2)
P(2)–N(2)
N(2)–P(3)
P(3)–F(4)
P(3)–F(5)
P(3)–N(3)
N(4)–P(4)
P(4)–N(6)
P(4)–N(8)
P(4)–N(5)
N(6)–P(5)
P(5)–F(7)
P(5)–F(6)
P(5)–N(7)
N(7)–P(6)
P(6)–F(9)
P(6)–F(8)
P(6)–N(8)
1.544(2)
1.579(2)
1.591(2)
1.642(2)
1.559(2)
1.523(2)
1.538(2)
1.568(3)
1.567(3)
1.525(2)
1.528(2)
1.576(2)
1.664(2)
1.618(3)
1.610(2)
1.608(2)
1.556(2)
1.530(2)
1.534(2)
1.568(3)
1.577(3)
1.527(2)
1.535(2)
1.560(2)
P(11)–F(11)
P(11)–N(11)
P(11)–N(31)
P(11)–N(41)
N(11)–P(21)
P(21)–F(31)
P(21)–F(21)
P(21)–N(21)
N(21)–P(31)
P(31)–F(41)
P(31)–F(51)
P(31)–N(31)
N(41)–P(41)
P(41)–N(61)
P(41)–N(81)
P(41)–N(51)
N(61)–P(51)
P(51)–F(71)
P(51)–F(61)
P(51)–N(71)
N(71)–P(61)
P(61)–F(91)
P(61)–F(81)
P(61)–N(81)
1.549(2)
1.577(3)
1.578(3)
1.635(3)
1.556(3)
1.524(2)
1.532(2)
1.558(4)
1.557(4)
1.522(3)
1.524(2)
1.566(3)
1.665(3)
1.603(3)
1.602(3)
1.611(3)
1.561(2)
1.522(2)
1.522(3)
1.559(3)
1.558(3)
1.523(2)
1.528(2)
1.561(3)
P(12)–F(12)
P(12)–N(12)
P(12)–N(32)
P(12)–N(42)
N(12)–P(22)
P(22)–F(32)
P(22)–F(22)
P(22)–N(22)
N(22)–P(32)
P(32)–F(42)
P(32)–F(52)
P(32)–N(32)
N(42)–P(42)
P(42)–N(62)
P(42)–N(82)
P(42)–N(52)
N(62)–P(52)
P(52)–F(72)
P(52)–F(62)
P(52)–N(72)
N(72)–P(62)
P(62)–F(92)
P(62)–F(82)
P(62)–N(82)
1.549(2)
1.574(3)
1.579(3)
1.641(3)
1.565(3)
1.521(2)
1.522(3)
1.562(4)
1.554(4)
1.531(2)
1.521(2)
1.563(3)
1.658(3)
1.600(3)
1.602(3)
1.617(3)
1.563(2)
1.525(2)
1.524(2)
1.563(3)
1.558(3)
1.525(3)
1.522(3)
1.562(3)
The numerical labels of local minima correspond to the Table 7;
a corresponds to 2Ba (or 2A, respectively), b corresponds to 2Bb.
Energy is expressed in kJ/mol relative to the lowest local mini-
mum labeled e; the step for isolines amounts to 2 kJ/mol;
a is the
torsion angle N(7)–P(4)–N(4)–P(1) in Fig. 1; b is the torsion angle
P(4)–N(4)–P(1)–F(1) in Fig. 1.
3.3. IR and raman spectra of 2A
The calculated IR spectra have been useful in the assigning
experimental bands to a mode of vibrational motion in most cases.
Fig. 7 compares calculated and experimental IR spectra of 2A.
The bands near 3444, 3423, 3302, 3282 cmꢀ1 in the experimen-
tal IR spectrum of 2A are in agreement with ADF calculations and
were assigned to valence vibrations
m of NH2 and NH group. The
broad band extending from 3150 cmꢀ1 to 2850 cmꢀ1 belongs to
the system of hydrogen bridges. There are two types of H-bridges
that are identical in both types of the molecules 2A and 2B (Figs.
2 and 5). The low intensity band at 2714 cmꢀ1 can be probably as-
signed to the combination vibration (overtone) of NH group (2 ꢂ d
NH). The double band of low intensity at 1559 and 1544 cmꢀ1 be-
longs unambiguously to the deformation vibration d of NH2 group
(ADF calculations 1540 cmꢀ1). The group of absorption bands in
the region from 1279 sh, 1252 vs, 1196 s to 1180 sh cmꢀ1, can
by ascribed, with agreement with ADF calculations (1282 s, 1278
vs, 1247 m, 1217 w) to several types of vibrations: deformation
minima and the first order saddle points are thermally accessible.
So, the molecule is stereochemically nonrigid which is connected
not only to the P–NH–P bridge but also to the easy distortions of
the P3N3 ring that is planar and comparably rigid, perhaps, only
in P3N3F6 [21,22]. The Fig. 6 suggests that all barriers to internal
vibration d of NH group, valence vibrations
m of both phosphazene

V. Richterová et al. / Polyhedron 28 (2009) 3078–3086
3085
Table 4
Selected angles (°) for 2A and 2B.
2A
2Ba
2Bb
N(1)–P(1)–N(3)
N(2)–P(2)–N(1)
N(3)–P(3)–N(2)
P(2)–N(1)–P(1)
P(3)–N(2)–P(2)
P(3)–N(3)–P(1)
N(8)–P(4)–N(6)
N(7)–P(5)–N(6)
N(8)–P(6)–N(7)
P(5)–N(6)–P(4)
P(6)–N(7)–P(5)
P(6)–N(8)–P(4)
F–P–Fa
117.1(1)
119.3(1)
119.7(1)
122.3(2)
120.3(2)
121.1(2)
114.0(1)
119.8(1)
119.9(1)
123.1(2)
119.6(2)
122.9(2)
98.0
N(11)–P(11)–N(31)
N(21)–P(21)–N(11)
N(31)–P(31)–N(21)
P(21)–N(11)–P(11)
P(31)–N(21)–P(21)
P(31)–N(31)–P(11)
N(81)–P(41)–N(61)
N(71)–P(51)–N(61)
N(81)–P(61)–N(71)
P(51)–N(61)–P(41)
P(61)–N(71)–P(51)
P(61)–N(81)–P(41)
F–P–Fa
117.3(2)
119.5(2)
119.1(2)
121.6(2)
120.8(2)
121.5(2)
114.3(2)
119.2(2)
119.7(2)
123.1(2)
120.2(2)
122.3(2)
98.4
N(12)–P(12)–N(32)
N(22)–P(22)–N(12)
N(32)–P(32)–N(22)
P(22)–N(12)–P(12)
P(32)–N(22)–P(22)
P(32)–N(32)–P(12)
N(82)–P(42)–N(62)
N(72)–P(52)–N(62)
N(82)–P(62)–N(72)
P(52)–N(62)–P(42)
P(62)–N(72)–P(52)
P(62)–N(82)–P(42)
F–P–Fa
116.6(2)
118.8(2)
119.8(2)
121.7(2)
120.4(2)
121.2(2)
113.7(2)
119.2(2)
119.6(2)
123.2(2)
119.8(2)
123.1(2)
98.5
F(1)–P(1)–N(4)
N(5)–P(4)–N(4)
P(1)–N(4)–P(4)
101.5(1)
102.2(1)
128.6(1)
F(11)–P(11)–N(41)
N(51)–P(41)–N(41)
P(11)–N(41)–P(41)
102.6(1)
102.3(2)
129.4(2)
F(12)–P(12)–N(42)
N(52)–P(42)–N(42)
P(12)–N(42)–P(42)
98.1(1)
100.4(2)
124.9(2)
a
Average.
Table 5
Hydrogen bonds for 2A and 2B (Å and °).
D–Hꢁ ꢁ ꢁA
d(D–H)
d(Hꢁ ꢁ ꢁA)
d(Dꢁ ꢁ ꢁA)
<(DHA)
2Aa
2Bb
N(4)–H(1)ꢁ ꢁ ꢁN(6)#1
N(5)–H(2)ꢁ ꢁ ꢁN(3)#1
N(5)–H(3)ꢁ ꢁ ꢁN(8)#2
0.88
0.66
0.86
2.19
2.67
2.34
2.937(3)
3.253(4)
3.145(4)
142.8
147.2
155.7
N(41)–H(11)ꢁ ꢁ ꢁN(61)#1
N(51)–H(21)ꢁ ꢁ ꢁN(31)#1
N(51)–H(31)ꢁ ꢁ ꢁN(81)#2
N(52)–H(32)ꢁ ꢁ ꢁN(82)#3
N(42)–H(12)ꢁ ꢁ ꢁN(62)#4
0.88
0.81
0.91
0.86
0.88
2.20
2.57
2.25
2.25
2.23
2.927(4)
3.217(4)
3.114(4)
3.102(4)
2.903(4)
139.1
137.9
158.3
171.3
132.8
a
Symmetry transformations used to generate equivalent atoms:
#1 ꢀx + 1, ꢀy, ꢀz + 1,
#2 ꢀx + 2, ꢀy, ꢀz + 1.
b
Symmetry transformations used to generate equivalent atoms:
#1 ꢀx + 1/2, ꢀy + 1/2, ꢀz + 1,
#2 ꢀx + 1/2, ꢀy + 3/2, ꢀz + 1,
#3 ꢀx, ꢀy + 1, ꢀz,
#4 ꢀx, ꢀy + 2, ꢀz.
cycles (denoted as ‘‘breathing” of the cycle), the coupled vibrations
d NH, and valence vibrations
m of phosphazene cycles.
Fig. 6. Potential energy surface for the rotations around bonds P–N in the P–NH–P
bridge in 2. All other coordinates except for
a
and b were optimized.
Table 6
Selected metrical parameters of X-ray and ADF-calculation.
2A
2Ba
2Bb
Torsion angles (°)
N(7)–P(4)–N(4)–P(1)
P(4)–N(4)–P(1)–F(1)
N(5)–P(4)–N(4)–P(1)
P(4)–N(4)–P(1)–N(2)
X-ray
20
28
163
153
ADF
25
43
158
140
Torsion angles (°)
X-ray
18
29
165
153
ADF
25
43
158
140
Torsion angles (°)
X-ray
18
157
165
23
ADF
24
164
156
15
N(71)–P(41)–N(41)–P(11)
P(41)–N(41)–P(11)–F(11)
N(51)–P(41)–N(41)–P(11)
P(41)–N(41)–P(11)–N(21)
N(72)–P(42)–N(42)–P(12)
P(42)–N(42)–P(12)–F(12)
N(52)–P(42)–N(42)–P(12)
P(42)–N(42)–P(12)–N(22)
Bond angles (°)
F(1)–P(1)–N(4)
N(4)–P(4)–N(5)
P(1)–N(4)–P(4)
N(1)–P(1)–N(3)
N(6)–P(4)–N(8)
X-ray
101.5
102.2
128.6
117.1
113.9
ADF
103.2
99.5
129.3
119.8
117.5
Bond angles (°)
X-ray
102.6
102.3
129.4
117.3
114.3
ADF
103.2
99.5
129.3
119.8
117.5
Bond angles (°)
X-ray
98.1
100.4
124.9
116.6
113.7
ADF
97.1
99.6
128.3
118.9
117.4
F(11)–P(11)–N(41)
N(41)–P(41)–N(51)
P(11)–N(41)–P(41)
N(11)–P(11)–N(31)
N(61)–P(41)–N(81)
F(12)–P(12)–N(42)
N(42)–P(42)–N(52)
P(12)–N(42)–P(42)
N(12)–P(12)–N(32)
N(62)–P(42)–N(82)
Bond lengths (Å)
P(1)–N(1)
P(1)–N(3)
P(1)–N(4)
P(4)–N(4)
P(4)–N(5)
P(4)–N(6)
P(4)–N(8)
X-ray
1.58
1.59
1.64
1.66
1.61
1.62
1.61
ADF
1.59
1.59
1.66
1.69
1.65
1.60
1.60
Bond lengths (Å)
P(11)–N(11)
P(11)–N(31)
P(11)–N(41)
P(41)–N(41)
P(41)–N(51)
P(41)–N(61)
P(41)–N(81)
X-ray
1.58
1.58
1.64
1.67
1.61
1.60
1.60
ADF
1.59
1.59
1.66
1.69
1.65
1.60
1.60
Bond lengths (Å)
P(12)–N(12)
P(12)–N(32)
P(12)–N(42)
P(42)–N(42)
P(42)–N(52)
P(42)–N(62)
P(42)–N(82)
X-ray
1.57
1.58
1.64
1.66
1.62
1.60
1.60
ADF
1.59
1.59
1.67
1.68
1.66
1.60
1.60

3086
V. Richterová et al. / Polyhedron 28 (2009) 3078–3086
[8] C.W. Allen, J. Fire Sci. 11 (1993) 320.
Table 7
[9] J.K. Valaitis, G.S. Kymer, J. Appl. Polym. Sci. 23 (1979) 765.
[10] J.P. Critchley, G.J. Knight, M.M. Wright, Heat-Resistant Polymers, Plenum Press,
New York, 1983.
[11] H.R. Allcock, in: M. Chasám, R. Langer (Eds.), Biodegradable Polymers as Drug
Delivery Systems, Marcel Dekker, New York, 1990, p. 163.
[12] A.G. Scopelianos, in: S.W. Shalaby (Ed.), Biomedical Polymers, Hanser, Munich,
1994, p. 153.
[13] L.G. Payne, S.A. Jenkins, A. Andrianov, B.E. Roberts, in: M.F. Powell, M.J.
Newman (Eds.), Vaccine Design: The Subunit and Adjuvant Approach, Plenum
Press Div, New York, 1995, p. 473.
[14] L.G. Payne, S.A. Jenkins, A. Andrianov, R. Langer, B.E. Roberts, in: J. Mestecky
et al. (Eds.), Advances in Mucose Immunology, Plenum Press, New York, 1995,
p. 1475.
Torsion angles
conformational PES.
a and b for the local energy minima on the two-dimensional
Conformera
E (kJ) molꢀ1b
a
(°)c
b (°)d
a
b
c
d
e
f
1.7
12.5
0.9
24
23
18
164
40
82
1.1
0.0
3.8
11.3
7.8
20
280
204
167
260
54
102
147
140
152
g
h
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a
The numerical labels correspond to Fig. 6.
Energy relative to the lowest local minimum e.
b
c
a
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d
b is the torsion angle P(4)–N(4)–P(1)–F(1) in Fig. 1.
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Theoretical Chemistry, Vrije Universteit, Amsterdam, The Netherlands, http://
www.scm.com.
Acknowledgements
This work was supported by the Ministry of Education, Youth,
and Sports of the Czech Republic, Grant No. MSM0021622411.
The authors express their gratitude to the Czech Grant Agency
for the Grant No. 203/02/0436 and the Grant KAN101630651 of
the Czech Academy of Sciences.
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