Synthesis and Characterization of New BIS(Pentafluoroethyl)Phosphinic Acid Amides and Hydrazides. Crystal Structure of (C2F5)2P(O)NH2

Article abstract of DOI:10.1080/10426507.2013.865127

Previously unknown bis(pentafluoroethyl)phosphinyl amides and hydrazides have been prepared in good yields by the reaction of bis(pentafluoroethyl)phosphinyl chloride or tris(pentafluoroethyl)phosphine oxide with the corresponding primary amines or hydraz

Full text of DOI:10.1080/10426507.2013.865127

Phosphorus, Sulfur, and Silicon, 189:1489–1502, 2014
Copyright ꢀC Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426507.2013.865127
SYNTHESIS AND CHARACTERIZATION OF NEW
BIS(PENTAFLUOROETHYL)PHOSPHINIC ACID
AMIDES AND HYDRAZIDES. CRYSTAL STRUCTURE
OF (C2F5)2P(O)NH2
Dana Bejan,1 Vasile Dinoiu,2 Nikolai Ignat’ev,3
Eduard Bernhardt,1 and Helge Willner1
1Inorganic Chemistry, Bergische University of Wuppertal, Gauss Str. 20,
D-42119 Wuppertal, Germany
2Romanian Academy, Institute of Organic Chemistry “C. D. Nenitzescu”,
Spl. Independentei 202B, 77141 Bucharest, Romania
3Merck KGaA, PM-ABE, Frankfurter Str. 250, D-64293 Darmstadt, Germany
GRAPHICAL ABSTRACT
Abstract Previously unknown bis(pentafluoroethyl)phosphinyl amides and hydrazides have
been prepared in good yields by the reaction of bis(pentafluoroethyl)phosphinyl chloride or
tris(pentafluoroethyl)phosphine oxide with the corresponding primary amines or hydrazines.
The crystal structure of (C2F5)2P(O)NH2 was determined. The compound (C2F5)2P(O)NH-
NHCH2C6H2-3,5-(t-C4H9)-4-OH was oxidized with PbO2 to the corresponding oxo-radical.
Keywords Bis(pentafluoroethyl)phosphinic acid; amides; hydrazides; crystal structure
INTRODUCTION
Amides of di(alkyl)phosphinic acids or diamides of alkylphosphonic acids are well-
known classes of phosphorus-nitrogen compounds.1 Numerous phosphorus amides have
been synthesized since the first organophosphorus compounds were prepared in the nine-
teenth century.2 Some phosphorus amides are useful chemicals for practical applications,
Received 9 September 2013; accepted 2 November 2013.
Address correspondence to Nikolai Ignat’ev, Merck KGaA, PM-ABE, Frankfurter Str. 250 D-64293, Darm-
stadt, Germany. E-mail: nikolai.ignatiev@merckgroup.com
Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/gpss.
1489

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D. BEJAN ET AL.
for instance phosphoric acid hexamethyl triamide is a well-known polar solvent. Cyclophos-
phamides are valuable anticancer drugs.2
Only a few fluorinated phosphinic acid amides are described in the literature.
Their syntheses are based on interaction of phosphinic acid chloride with amines. For
example, bis(perfluoroalkyl)phosphinic acid amides (CnF2n+2)2P(O)NHR (R = H, CH3,
C6H5, 3-FC6H4, and 4-FC6H4) were prepared in moderate yields by the reaction of
(CnF2n+1)2P(O)Cl (n = 1, 3, and 4) with ammonia, methylamine, and aromatic amines.3–5
Tris(perfluoroalkyl)phosphine oxides are also suitable starting materials for the synthesis
of bis(perfluoroalkyl)phosphinic acid amides. Burg and Sarkis reported the quantitative
reaction of tris(trifluoromethyl)phosphine oxide with dimethyl amine.6 Later on, it was
found that tris(nonafluorobutyl)phosphine oxide reacts with dimethyl amine resulting in
the formation of a complex mixture of products.7
There are few reports on the preparation of phosphinic acid hydrazides,
for example: (CH3)2P(O)NHNHPh and Ph2P(O)NHNHPh;8 (CH3)2P(O)NHNH2;9
(C2H5)2P(O)NHNH(t-C4H9);10 and Ph2P(O)NHNH2 and Ph2P(O)NHN(CH3)2,11 but no
fluorinated phosphinyl hydrazides are described in the literature.
Recently Merck KGaA (Darmstadt, Germany) has applied for a patent claiming
the preparation of bis(perfluoroalkyl)phosphinyl hydrazides.12 Here, the syntheses and
properties of previously unknown bis(perfluoroalkyl)phosphinyl amides and hydrazides
are described.
RESULTS AND DISCUSSION
Synthesis of Bis(pentafluoroethyl)phosphinic Acid Amides
Tris(pentafluoroethyl)phosphine oxide A reacts with ammonia, primary aliphatic
and aromatic amines yielding the corresponding bis(pentafluoroethyl)phosphinyl amides
C (Scheme 1).
Scheme 1 Preparation of bis(pentafluoroethyl)phosphinyl amides.
The strong electrophile, tris(pentafluoroethyl)phosphine oxide A, reacts with
equimolar quantities of primary amines forming the intermediate complex B, which
is not stable under the reaction conditions and is converted into the final product,
bis(pentafluoroethyl)phosphinyl amide C. The reactions proceed at low temperature
(−30 to 20◦C).
The yields of bis(pentafluoroethyl)phosphinyl amides C generally range from good
to excellent as it is shown in Table 1. A low yield is observed in the reaction with aniline
6c. This can be attributed to the reduced nucleophilicity of aromatic amines.

SYNTHESIS AND CHARACTERIZATION OF NEW BIS(PENTAFLUOROETHYL)
1491
Table 1 Products from the reaction of (C2F5)3P(O) with NH2R and their melting points and yield
Product (C)
R
Mp (◦C)
Yield (%)
1c
2c
3c
4c
5c
6c
7c
8c
9c
H
CH2C6H5
CH2CH2C6H5
CH2C6H4CH3
CH2C6H4OCH3
C6H5
98
94
110
102
90
141
150
210
76
86
89
84
62
72
13
76
75
92
C6H4CH3
CH2CH2CH2CH3
CH2CH(C2H5)(CH2)3CH3
The hydrolytic stability of bis(pentafluoroethyl)phosphinyl amides depends on the
substituent R. Amides 2c–9c having longer alkyl chain attached to the nitrogen atom
are more stable against hydrolysis in comparison to (C2F5)2P(O)NH2 1c which forms an
ammonium salt by dissolving in wet solvents.
Details of the reaction’s conditions and workup procedures are given in the experi-
mental part.
Synthesis of Bis(pentafluoroethyl)phosphinic Acid Hydrazides
Reaction of A with different hydrazines in dry acetonitrile at room temperature yields
bis(pentafluoroethyl)phosphinic acid hydrazides D (Scheme 2).
C2F5
H
C2F5
C2F5
O
C2F5
C2F5
P
O
+
HN
NR'R''
P
- C2F5H
NH NR'R''
D
A
R' = H, CH3; R'' = CH3, C6H5, CH2C6H2-3,5-(t-C4H9)-4-OH
Scheme 2 Synthesis of substituted phosphinyl hydrazides D from (C2F5)3P = O.
Bis(pentafluoroethyl)phosphinic acid chlorides13 E are more reactive towards
hydrazines (Scheme 3). CaH2 was used as scavenger for HCl to avoid the formation of
[NH3NRR’]Cl as a side product.
H
C2F5
C2F5
O
C2F5
C2F5
O
P
+
HCl
HN
R' = H; R'' = CH3, C6H5
2 HCl CaCl2
Scheme 3 Synthesis of substituted phosphinyl hydrazides D from (C2F5)2P(O)Cl.
NR'R''
+
P
Cl
NH
NR'R''
E
D
CaH2
+
+
2 H2

1492
D. BEJAN ET AL.
Table 2 Products from the reaction of (C2F5)3P(O) with NH2NRR’ and their melting points
Product (D)
R
R’
Mp (◦C)
Yield, (%)
1d
2d
H
H
H
H
CH3
H
CH3
CH3
C6H5
C6H5
CH3
72
72
88
88
71
84
<75∗
81
77∗
82
3d
4d
NHCH2C6H2-3,5-(t-C4H9)-4-OH
107
88
∗Obtained from the reaction with (C2F5)2P(O)Cl.
C2F5
C2F5
C2F5
C2F5
O
O
C4H9-t
OH
C4H9-t
O.
P
P
PbO2
NH NHCH2
NH NHCH2
Toluene
C4H9-t
C4H9-t
Scheme 4 Oxidation of bis(pentafluoroethyl)phosphinyl-N(3,5-di-t-butyl-4-hydroxy-benzyl)hydrazide to form a
stable radical.
The yields of bis(pentafluoroethyl)phosphinyl hydrazides D obtained according to
Scheme 3 are lower in comparison to those in the reaction of hydrazines with (C2F5)3P(O)
due to the more difficult product isolation.
The bis(pentafluoroethyl)phosphinyl hydrazides (Table 2) are very moisture sensitive
compounds. For this reason, all reactions with hydrazines were carried out using vacuum
line techniques and glass flasks equipped with a glass valve with PTFE piston (Young,
London). The manipulations with nonvolatile compounds were carried out in a glove box
under argon. Volatile compounds were handled at the vacuum line. Traces of water in the
reaction mixture or in the solvent (acetonitrile) caused hydrolysis of the products.
Bis(pentafluoroethyl)phosphinyl-N(3,5-di-t-butyl-4-hydroxy-benzyl)hydrazide 4d
can be oxidized with PbO2 in toluene to a stable radical (Scheme 4).
The reaction mixture was stirred for 30 min at room temperature. The colorless
solution changed to yellow indicating the formation of a radical species, which can be also
followed in the UV-VIS spectrum (Figure 1). In a closed flask, the color remains unchanged
for several weeks.
NMR Study
1
The H, 19F, 31P NMR data for all synthesized compounds are given in the experi-
mental part. The NMR spectra were measured in dry CD3CN or CD2Cl2 solutions.
In the 1H NMR spectrum of 1c a broad singlet and in the spectra of amides 2c–9c a
broad doublet at about 5 ppm is assigned to the NH-proton.
The 19F NMR spectra of the bis(pentafluoroethyl)phosphinyl amides C are more
complex. Due to the presence of diastereotopic fluorine atoms in α-position, the C2F5
group in these spectra gives a singlet at −81 ppm and multiplets at −125 ppm with an
integral intensity ratio of 3:2.
The nature of R group in the amides C has moderate influence on the phosphorus
chemical shifts (7–13 ppm). Figure 2 shows the proton-coupled and -decoupled 31P NMR

SYNTHESIS AND CHARACTERIZATION OF NEW BIS(PENTAFLUOROETHYL)
1493
2
(C2F5)2P(O)NH-NH-CH2-C6H3(t-C4H9)2(OH) in toluene
1,8
(C2F5)2P(O)NH-NH-CH2-C6H3(t-C4H9)2(OH) in toluene w ith PbO2
1,6
1,4
1,2
1
0,8
0,6
0,4
0,2
0
300
325
350
375
400
425
450
475
500
Wavelength / nm
Figure 1 UV-VIS spectrum of bis(pentafluoroethyl)phosphinyl-N(3,5-di-t-butyl-4-hydroxy-benzyl)hydrazide
and the corresponding oxo-radical.
spectrum of 2c. The 31P NMR spectrum showed overlapping triplet of triplet of doublet
of triplet, due to the P,H spin-spin coupling (2JPH = 20.3 Hz and 3JPH = 11.6 Hz). In the
1
31P{ H} NMR spectrum an overlapping triplet of triplets is observed due to the coupling
with the four 19F nuclei of the two CF2 groups.
Bis(pentafluoroethyl)phosphinic acid hydrazides were also characterized by 1H, 19F,
31P NMR spectroscopy. The 19F NMR spectrum of the C2F5 group is complex as a
consequence of nonequivalent fluorine atoms in the CF2 groups. The experimental 19F
1
Figure 2 31P and 31P{ H} NMR spectra of (C2F5)2P(O)NHCH2C6H5 (2c) in acetonitrile-D3.

1494
D. BEJAN ET AL.
Figure 3 Simulated (top) and observed (bottom) 19F NMR spectrum of (C2F5)2P(O)NHNHC6H5 2d, resonances
of the CF2 groups; solvent: acetonitrile-D3.
NMR parameters were used to simulate (gNMR 4.1 program) the 19F NMR spectrum of
(C2F5)2P(O)NHNHC6H5 2d as an AA’BB’X spin system. The observed and simulated AA’
part of the spectrum is depicted in Figure 3. The 31P NMR spectrum of 2d shows an overlap-
ping triplet of triplets of doublets of doublets (Figure 4) due to the P,H spin-spin-coupling
(2JPH = 44.2 Hz and 3JPH = 4.0 Hz).
Vibrational Spectroscopy
The IR and Raman spectra of (C2F5)2P(O)NH2 1c are shown in Figure 5 and all band
positions are listed in the experimental part. Two ν(N–H) stretching bands are expected
for one NH2 group, but 4 are observed (3344 w, 3222 m, 3087 m, 2888 w) because four
molecules are linked via hydrogen bonds in the unit cell (see crystal structure below). Other
fundamental vibrations in the region between 1400 and 1000 cm−1, are attributed to the
P O stretching, NH2 deformation and CF stretching modes. The strongest Raman band at
754 cm−1 is assigned to the symmetric CF3 deformation. A more detailed description of
modes is not possible, due to strong vibrational coupling. The spectra are just of “finger
pint” value.
Crystal Structure of (C2F5)2P(O)NH2
The structural parameters for (C2F5)2P(O)NH2 and the values of angles/distances
are given in the Supplementary Material. The asymmetric unit contains one independent
formula unit (Figure 6).

SYNTHESIS AND CHARACTERIZATION OF NEW BIS(PENTAFLUOROETHYL)
1495
Figure 4 31P NMR spectrum of (C2F5)2P(O)NHNHC6H5 2d in acetonitrile–D3.
Figure 5 Infrared and Raman spectra of solid (C2F5)2P(O)NH2 recorded for the neat compound.
Figure 6 Molecular structure of the asymmetric unit of (C2F5)2P(O)NH2 in the unit cell. Thermal ellipsoids are
drawn at the 50% probability level.

1496
D. BEJAN ET AL.
Figure 7 Network of hydrogen bonds in (C2F5)2P(O)NH2. Thermal ellipsoids are drawn at the 50% probability
level.
The phosphorus atom is tetrahedrally coordinated. The interatomic distances of the
C F, C C, C P, P O, P N bonds and F C F, C C F, P C F, C P C, C P O,
C P N, O P N angles observed for (C2F5)2P(O)NH2 are in the typical range as for
example in P(O)(NH2)3,14 H[{(C2F5)2P(O)}2N],15 and POCl3.16 The crystal structure is
stabilized by intermolecular hydrogen bonds of the types N–H···O (H1···O 2.20(4), H2···O
2.30(5), N···O 2.907(4), 2.916(5), and N–H 0.72(4) Å, (Figure 7). These form a one-
dimensional hydrogen bonds network along the a-axis.
EXERIMENTAL
Analytical Procedures
All NMR spectra were recorded with a Bruker Avance DRX-400 MHz
(1H, 400.13 MHz; 19F, 376.49 MHz; 31P, 161.97 MHz) spectrometer. For simulation of
the NMR spectra the program gNMR 4.1 was used. The spectra were recorded at room
temperature. The chemical shifts are given in parts per million (ppm) relative to external
TMS (1H), CFCl3 (19F) and 85% H3PO4 (31P).
Elemental analyses were performed using a HEKATECH EA 3000 (Wegberg,
Germany) elemental analyzer and the Callidus software.
Infrared spectra were recorded at room temperature with a FTIR spectrometer
TENSOR 27 (Bruker, Karsruhe, Germany) equipped with an ATR IR accessory
(HARRICK, MVP StarTM) with a diamond as the ATR crystal operating in the region
4000–400 cm−1
.
Raman spectra were recorded at room temperature with a Bruker EQUINOX 55 FT
Raman spectrometer using the 9394.8 cm−1 exciting line (500 mW) of an Nd: YAG laser.
Solid samples were placed in melting point capillaries and used for recording spectra in the
region 3000–50 cm−1 with a resolution of 2 cm−1. For each spectrum, 32–500 scans were
added.

SYNTHESIS AND CHARACTERIZATION OF NEW BIS(PENTAFLUOROETHYL)
1497
The Schmelzpunkt SMP 10 – STUART apparatus was usedfor visual determinations
of the melting point in glass capillaries (Ø 2 mm).
X-ray Crystal Structure Determination
(a) Crystal Growth and Crystal Mounting. Single crystals of (C2F5)2P(O)NH2
were obtained by recrystallization from a mixture of benzene and hexane (1:2). Suitable
crystals were selected under the microscope and mounted.
(b) Collection and Reduction of X-Ray Data. Crystals were mounted on an
Oxford Diffraction Gemini E Ultra diffractometer, equipped with a 2K × 2K EOS CCD
area detector, a four-circle κ goniometer, an Oxford Instruments cryojet, and sealed-tube
enhanced (Mo) and enhanced ultra (Cu) sources. For data collection, the Mo-Kα radiation
(λ = 0.71073 Å) was used. The diffractometer was controlled by CrysAlisPro Graphical
User Interface software.17 The diffraction data collection strategy was optimized with
respect to complete coverage and consisted of 10 ω scans with a width of 1◦, respectively.
The data collection was carried out at 150 K, in a 1024 × 1024 pixel mode using 2 ×
2 pixel binning. Processing of the raw data, scaling of the diffraction data, and application
of an empirical absorption correction was completed by using the CrysAlisPro program.17
(c) Solution and Refinement of the Structure. The solution of the structure
was performed by direct methods, which located the positions of all atoms. The final refine-
ment was obtained by introducing anisotropic thermal parameters and the recommended
weightings for all atoms. All calculations were performed using the WinGX v1.64.05 pack-
age program for structure determination, solution refinement, and molecular graphics.18–21
Crystallographic data for (C2F5)2P(O)NH2 (1c, CCDC 876561) were deposited with
the Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB21EZ, UK.
Copies of the data can be obtained on www.ccdc.cam.ac.uk/data request/cif Fax: (+44-
1223-336-033; E-Mail: deposit@ccdc.cam.ac.uk).
Synthesis of Amides and Hydrazides
Bis(pentafluoroethyl)phosphinyl Amide, (C2F5)2P(O)NH2 (1c). 35.9 g
(0.089 mol) of (C2F5)3PO was placed in a 250 mL round bottom flask, equipped with
a cooler condenser (dry ice/ethanol), magnetic stirring bar, gas dispersion tube and a
thermometer. Excess of ammonia gas was bubbled through (C2F5)3PO for about 20 min.
The reaction mixture was kept at temperatures between −35 and −30◦C using an ethanol
bath. The reaction end was visually estimated when the resulting white product was
formed. To complete the reaction, the mixture was kept at −30◦C for 10 min and then
all volatile products were removed in vacuum (10−3 mbar). 23.1 g of a white solid was
1
obtained. Yield 86%; mp: 98◦C. H NMR (CD3CN): δ = 5.29 (br s, NH2). 19F NMR
2
(CD3CN): δ = −81.1 (s, 6F, CF3), −124.9 (m, 2F, CFa), −127.7 (m, 2F, CFb), JPFa
=
78.3 Hz, 2JPFb = 83.6 Hz, 2JFaFb = 338.6 Hz. 31P NMR (CD3CN): δ = 12.9 (quint of m,
2JPF = 81.2 Hz). IR (cm−1): 3344 (w); 3222 (m); 3087 (m); 2884 (w); 1313 (m); 1290 (m);
1259 (vs); 1209 (vs); 1149 (vs); 1127 (s); 1092 (s); 1068 (m); 1020 (w); 994 (s); 971 (m);
948 (m); 756 (m); 751 (m); 689 (vw); 669(m); 637 (m); 619 (w); 602(s); 575 (s); 563 (m);
548 (m); 521 (s); 513 (s); 489(s); 468 (s); 434 (m); 426 (m). Raman (cm−1): 1333(10);
1292 (4); 1266 (15); 1231 (10); 1140 (5);1071(4); 1020 (5); 952 (5); 754 (100); 641 (26);
596 (10); 545 (5); 471 (6); 370 (16); 327 (10); 284 (10); and 151 (30).

1498
D. BEJAN ET AL.
Bis(pentafluoroethyl)phosphinyl N–(benzyl)amide, (C2F5)2P(O)NHCH2C6
H5 (2c). A 10 mL flask, equipped with a magnetic stirring bar, septum and drying tube
ꢀR
filled with Sicapent , was charged under nitrogen with (C2F5)3PO (3.22 g, 7.9 mmol).
The benzyl amine (0.85 g, 7.9 mmol) was slowly added under good stirring at 0◦C. The
reaction is exothermic and was let to warm up at room temperature to liberate C2F5H. The
flask was connected to the membrane vacuum for 5 min to remove not reacted (C2F5)3PO.
The resultant solid was solved in benzene and transferred to a separator funnel and washed
three times with water. The solvent was distilled off under reduced pressure (< 0.05 mbar).
After drying under vacuum, 2.76 g of white solid material was obtained. Yield: 89%; mp:
1
2
94◦C. H NMR (CD3CN): δ = 7.39–7.29 (m, 5H, CH); 5.68 (br d, JPH = 20.3 Hz, 1H,
NH), 4.31 (dd, 2JPH = 11.6 Hz, 3JHH = 7.1 Hz, 2H, CH2). 19F NMR (CD3CN): δ = −81.0
(m, 6F, CF3), −124.5 (dd of m, 2F, CFa), −126.6 (dd of m, 2F, CFb), 2JPFa = 79.2 Hz, 2JPFb
= 86.0 Hz, 2JFaFb = 317.7 Hz. 31P NMR (CD3CN): δ = 12.6 (ttdt, 2JPH = 17.9 Hz, 3JPH
=
10.6 Hz, 2JPFa = 79.8 Hz, 2JPFb = 82.4 Hz. For C11H8NF10OP Calcd: C 33.78; H 2.06; N
3.58; Found C 33.92; H 2.03; N 4.14%.
Bis(pentafluoroethyl)phosphinyl N–(2–phenylethyl)amide, (C2F5)2P(O)
NHCH2CH2C6H5 (3c). Under an inert atmosphere of nitrogen 2.29 g (17.7 mmol) of
2–phenylethyl amine was added slowly to (C2F5)3PO (7.15 g, 17.7 mmol) at 0◦C with
good stirring. During this time, the reaction mixture turned into a white solid. Then the
same procedure was followed as that described above. 6.12 g of white solid was obtained.
1
Yield: 84%; mp: 110◦C. H NMR (CD3CN): δ = 7.34–7.26 (m, 5H, CH), 5.26 (br d,
2JPH = 20.3 Hz, 1H, NH); 3.37 (m, 2H, CH2), 2.84 (t, 3JHH = 7.3 Hz, 2H, CH2). 19F NMR
2
(CD3CN): δ = −81.1 (m, 6F, CF3), −124.6 (m, 2F, CFa), −126.6 (m, 2F, CFb), JPFa
=
76.6 Hz; 2JPFb = 84.7 Hz, 2JFaFb = 319.9 Hz. 31P NMR (CD3CN): δ = 11.2 (quint of m,
2JPF = 82.5 Hz).
Bis(pentafluoroethyl)phosphinyl N–(4–methylbenzyl)amide, (C2F5)2P(O)
NHCH2C6H4CH3 (4c). 4-CH3C6H4CH2NH2 (0.68 g, 5.96 mmol) was added carefully by
means of syringe to (C2F5)3P(O) (2 g, 5.96 mmol) and the resulting homogeneous solution
was stirred for 4 h at room temperature. The white precipitate formed was filtered off and
washed with water. Then the same procedure was followed as that described above. Yield:
1
2
62%; mp: 102◦C. H-NMR (CD3CN): δ = 7.25–7.35 (m, 4H, CH), 5.66 (br d, JPH
=
3
3
19.8 Hz, 1H, NH), 4.25 (dd, JHH = 7.1 Hz, JHH = 10.6 Hz, 2H, CH2), 2.31 (s, 3H,
CH3). 19F NMR (CD3CN): δ = −81.1 (m, 6F, CF3), −124.5 (m, 2F, CFa), −126.6 (m, 2F,
CFb); 2JPFa = 78.0 Hz, 2JPFb = 83.7 Hz, 2JFaFb = 318.4 Hz. 31P NMR (CD3CN): δ = 12.7
(quint of m, 2JPF = 81.2 Hz). For C12H10NF10OP: Calcd: C 35.57; H 2.49; N 3.46; Found:
C 35.84; H 2.56; N 3.43%.
Bis(pentafluoroethyl)phosphinyl N–(4–methoxybenzyl)amide, (C2F5)2
P(O)NHCH2C6H4OCH3 (5c). 4-CH3O-C6H4CH2NH2 (2.4 g, 5.96 mmol) was added
carefully by means of a syringe to (C2F5)3P(O) (0.68 g, 5.96 mmol) cooled in a two-
necked flask equipped with a standard assembly via an ice/water-bath. The reaction was
very violent and a solid white product was formed. The resulting solid was filtered off,
was dissolved in benzene, the mixture was transferred to a separator funnel and washed
three times with water. The solvent was distilled off and remaining product was dried under
vacuum (< 0.05 mbar). 1.8 g of a white solid material was obtained. Yield: 72%; mp: 90◦C.
1H-NMR (CD3CN): δ = 7.23 (m, 2H, CH), 6.90 (m, 2H, CH), 5.61 (br d, 2JPH = 20.7 Hz,
1H, NH), 4.24 (dd, 3JHH = 8.6 Hz, 3JHH = 10.4 Hz, 2H, CH2), 3.76 (s, 3H, CH3). 19F NMR
2
(CD3CN): δ = −81.1 (m, 6F, CF3), −124.6 (m, 2F, CFa), −126.6 (m, 2F, CFb), JPFa
=

SYNTHESIS AND CHARACTERIZATION OF NEW BIS(PENTAFLUOROETHYL)
1499
78.7 Hz, 2JPFb = 79.7 Hz, 2JFaFb = 320.4 Hz. 31P NMR (CD3CN): δ = 12.5 (quint of m,
2JPF = 81.0 Hz). For C12H10NF10O2P: Calcd: C 34.22; H 2.39; N 3.33; Found: C 34.46; H
2.11; N 3.67%.
Bis(pentafluoroethyl)phosphinyl N–phenylamide, (C2F5)2P(O)NHC6H5
(6c). The method was essentially the same as that outlined (described) above. C6H5NH2
(0.23 g, 2.48 mmol) was added carefully via syringe to (C2F5)3P(O) (1 g, 2.48 mmol), the
resulting homogeneous solution was stirred for 23 h at room temperature when a white
precipitate was formed. Filtration, washing with water and drying in vacuum (<10−2
1
mbar) gave 0.12 g of 6c. Yield: 13%; mp: 141◦C. H-NMR (CD3CN): δ = 7.5 (br d,
2JPH = 17.8 Hz, 1H, NH), 7.38–7.20 (m, 5H, CH). 19F NMR (CD3CN): δ = −81.0 (m, 6F,
CF3), −123.6 (m, 2F, CFa), −126.3 (m, 2F, CFb), 2JPFa = 77.8 Hz, 2JPFb = 85.4 Hz, 2JFaFb
= 337.9 Hz. 31P NMR (CD3CN): δ = 8.6 (tt, 2JPFa = 79.8 Hz, 2JPFb = 82.4 Hz).
For C10H6NF10OP: Calcd: C 31.85; H 1.60; N 3.71; Found: C 32.35; H 1.72; N
3.98%.
Bis(pentafluoroethyl)phosphinyl N–(4–methylphenyl)amide, (C2F5)2P(O)
NHC6H4CH3 (7c). A solution of p-methylphenylamine (0.29 g, 2.73 mmol) in 10 mL
benzene was added to (C2F5)3P(O) (1.1 g, 2.73 mmol) and the resultant mixture was stirred
at room temperature for 12 h to form a white precipitate. The solid product was filtered
off and washed with water. (C2F5)2P(O)NHC6H4CH3, 7c, was obtained in 76% isolated
yield; mp: 150◦C. 1H-NMR (CD2Cl2): δ = 7.15 (m, 4H, CH), 5.92 (br d, 2JPH = 17.3 Hz,
1H, NH), 2.31 (s, 3H, CH3). 19F NMR (CD2Cl2): δ = −80.4 (m, 6F, CF3), −122.7 (m, 2F,
CFa), −125.6 (m, 2F, CFb), 2JPFa = 76.2 Hz, 2JPFb = 93.9 Hz, 2JFaFb = 318.3 Hz. 31P NMR
2
2
(CD2Cl2): δ = 7.8 (tt, JPFa = 79.5 Hz, JPFb = 86.1 Hz). For C11H10NF10OP: Calcd: C
33.78; H 2.06; N 3.58; Found: C 33.94; H 1.85; N 3.69%.
Bis(pentafluoroethyl)phosphinyl N–(n–butyl)amide, (C2F5)2P(O)NHC4H9
(8c). n-C4H9NH2 (0.18 g, 2.48 mmol) was added drop-wise by means of a syringe, care-
fully, to (C2F5)3P(O) (1 g, 2.48 mmol), cooled in a two-necked flask equipped with a
standard assembly via an ice/water-bath. The reaction was very violent. The resulting
mixture was stirred at room temperature for 1 h when a solid white product was formed.
The solid was dissolved in benzene and the mixture was transferred to a separator fun-
nel and washed with water. The solvent was distilled off under reduced pressure yielding
0.66 g (75%) of a white compound (8c); mp: 210◦C. 1H-NMR (CD3CN): δ = 5.15 (br d,
2JPH = 16.7 Hz, 1H, NH); 3.13 m (CH2); 1.52 (m, 2H, CH2), 1.34 (m, 2H, CH2), 0.89
3
(t, JH,H = 7.3 Hz, 3H, CH3). 19F NMR (CD3CN): δ = −81.2 (m, 6F, CF3), −124.8 (m,
2F, CFa), −126.8 (m, 2F, CFb), 2JPFa = 79.7 Hz, 2JPFb = 82.3 Hz, 2JFaFb = 321.8 Hz. 31
P
NMR (CD3CN): δ = 12.5 (quint of m, 2JPF = 80.5 Hz. For C8H10NF10OP: Calcd: C 26.91;
H 2.82; N 3.92; Found: C 26.79; H 2.81; N 3.91%.
Bis(pentafluoroethyl)phosphinyl N–(2–ethylhexyl)amide, (C2F5)2P(O)NH
CH2CH(C2H5)(CH2)3CH3 (9c). The same procedure as described above was applied.
2–Ethylhexyl amine (2.19 g, 16.9 mmol) was added slowly to (C2F5)3PO (6.8 g, 16.9 mmol)
at 0◦C with good stirring. The product 9c was obtained as a white solid (glue) (6.45 g).
1
2
Yield: 92%; mp: 76◦C. H NMR (CD3CN): δ = 5.08 (br d, JPH = 19.8 Hz, 1H, NH),
3
3
3
3.05 (td, JPH = 9.6 Hz, JHH = 6.8 Hz, 1H, CH), 1.35 (m, 10H, CH2), 0.88 (t, JHH
=
7.1 Hz, 3H, CH3), 0.85 (t, 3JHH = 7.1 Hz, 3H, CH3). 19F NMR (CD3CN): δ = −81.1 (m,
6F, CF3), −124.6 (m, 2F, CFa), −126.5 (m, 2F, CFb), 2JPFa = 78.3 Hz, JPFb = 82.7 Hz,
2
2JFaFb = 322 Hz. 31P NMR (CD3CN): δ = 11.2 (dtt, JPH = 20.4 Hz, JPH = 9.8 Hz,
2
3
2JPF = 80.6 Hz).

1500
D. BEJAN ET AL.
Bis(pentafluoroethyl)phosphinyl N–(methyl)hydrazide, (C2F5)2P(O)NHN
HCH3 (1d). A dry 25 mL flask, equipped with a glass valve with PTFE piston (Young),
was charged in a vacuum line with 0.10 g (2.1 mmol) of methylhydrazine, 1 mL of dry
acetonitrile, and 1.3 g (3.2 mmol) of (C2F5)3PO. The reaction mixture was left stirring
at room temperature for 16 h and then all volatile products were removed under vacuum
(10−3 mbar). 0.58 g of a white solid product was obtained. Compound 1d was handled
1
in a dry–box for NMR and melting point measuring. Yield: 84%; mp: 72◦C. H NMR
2
(CD3CN): δ = 6.75 (br d, JPH = 39.2 Hz, 1H NH), 4.12 (br s, 1H, NH), 2.57 (s, 3H,
CH3). 19F NMR (CD3CN): δ = −81.4 (m, 6F, CF3), −122.4 (m, 2F, CFa), −124.6 (m, 2F,
CFb), 2JPFa = 70.1 Hz, 2JPFb = 82.0 Hz, 2JFaFb = 321.8 Hz. 31P NMR (CD3CN): δ = 8.9
(quint of d, 2JPF = 76.8 Hz, 2JPH = 40.9 Hz). For C5H5N2F10OP: Calcd: C 18.19; H 1.53;
N 8.49; Found: C 17.93; H 1.94; N 9.28%.
Bis(pentafluoroethyl)phosphinyl N–(phenyl)hydrazide, (C2F5)2P(O)NHN
HC6H5 (2d). Method A: A dry 25 mL flask, equipped with a glass valve with PTFE
piston (Young), was charged in a vacuum line with 0.47 g (4.3 mmol) of phenylhydrazine,
1 mL of dry acetonitrile, and 1.9 g (4.7 mmol) of (C2F5)3P(O). After 1 h stirring at room
temperature a homogeneous solution was formed. To complete the reaction, the mixture was
left stirring at room temperature for 20 h and then all volatile products were removed under
vacuum (10−3 mbar). The resulting slightly yellow solid material (1.37 g) was purified by
sublimation in high vacuum at 82◦C. Yield: 81%; mp: 88 ◦C. 1H NMR (CD3CN): δ = 7.46
(br d, 2JPH = 44.2 Hz, 1H, NH), 7.24–7.31 (m, 2H, arom-H), 7.00–6.92 (m, 3H, arom-H),
3
6.47 (d, JPH = 4.0 Hz, 1H, NH). 19F NMR (CD3CN): δ = −81.2 (m, 6F, CF3), −121.9
(m, 2F, CFa), −124.6 (m, 2F, CFb), 2JPFa = 73.9 Hz, 2JPFb = 82.8 Hz, 2JFaFb = 338.2 Hz.
31P NMR (CD3CN): δ = 8.9 (ddtt, 2JPH = 44.2 Hz, 3JPH = 4.3 Hz, 2JPFa = 78.4 Hz, 2JPFb
= 82.4 Hz). For C10H7N2F10OP: Calcd: C 30.63; H 1.80; N 7.14; Found: C 30.76; H 2.13;
N 7.47%.
Method B: A dry 25 mL flask, equipped with a glass valve with PTFE piston
(Young), was charged with 0.15 g of CaH2, 0.34 g (3.1 mmol) of phenylhydrazine and
1 mL of dry acetonitrile. At a vacuum line 1.5 g (4.6 mmol) of (C2F5)2P(O)Cl were
condensed to the reaction mixture. After warming up to room temperature, the reac-
tion mixture was left stirring for 20 h, filtered and washed with dry acetonitrile. Sub-
sequently all volatile materials were removed under vacuum (10−3 mbar). The resulting
yellow crystalline solid product (0.94 g) was handled only in a dry–box. Yield: 77%; mp:
88◦C.
Bis(pentafluoroethyl)phosphinyl N,N–di(methyl)hydrazide, (C2F5)2P(O)
NHN(CH3)2 (3d). A dry 25 mL flask, equipped with a glass valve with PTFE piston
(Young), was charged at a vacuum line with 0.23 g (3.8 mmol) of 1,1–dimethylhydrazine,
1 mL of dry acetonitrile and 1.78 g (4.4 mmol) of (C2F5)3P(O). The exothermic reaction
started at room temperature and the reaction mixture became homogeneous. The reaction
mixture was left stirring at room temperature for 15 h and then all volatile materials
were removed under vacuum (10−3 mbar). The white solid product (1.45 g) was handled
1
2
only in a dry–box. Yield: 82%; mp: 71◦C. H NMR (CD3CN): δ = 6.90 (br d, JPH
=
41.6 Hz, 1H, NH), 2.90 (s, 6H, CH3). 19F NMR (CD3CN): δ = −81.2 (m, 6F, CF3),
2
2
2
−121.4 (m, 2F, CFa), −124.9 (m 2F, CFb), JPFa = 71.7 Hz, JPFb = 82.4 Hz, JFaFb
=
=
337.2 Hz. 31P NMR (CD3CN): δ = 6.5 (dtt, JPH = 41.4 Hz, JPFa = 75.5 Hz, JPFb
2
2
2
81.3 Hz). For C6H7N2F10OP: Calcd: C 20.94; H 2.05; N 8.14; Found: C 21.25; H 2.58;
N 8.87%.

SYNTHESIS AND CHARACTERIZATION OF NEW BIS(PENTAFLUOROETHYL)
1501
Bis(pentafluoroethyl)phosphinyl N–[3,5–di(t–butyl)–4–hydroxybenzyl]-
hydrazi-de, (C2F5)2P(O)NHNHCH2[3,5–(t–C4H9)2–C6H2–4–OH] (4d)
A dry 25 mL flask, equipped with a glass valve with PTFE piston (Young), was
charged with 0.80 g (3.2 mmol) of 3,5–di(t–butyl)–4–hydroxyphenyl hydrazine and then
at a vacuum line with 1 mL of dry acetonitrile and 1.5 g (3.7 mmol) of (C2F5)3P(O) at
0◦C. After stirring for 30 min at room temperature a homogeneous solution is formed. To
complete the reaction, the mixture was left stirring at room temperature for 21 h and then
all volatile products were removed under vacuum (10−3 mbar). The white solid product
(1.5 g) was handled only in a dry–box. Yield: 88%; mp: 106–108◦C. 1H NMR (CD3CN):
δ = 7.09 (s, 2H, CH), 6.69 (br d, 2JPH = 39.6 Hz, 1H NH), 5.41 (s, 1H, NH), 4.38 (br s,
1H, OH), 3.82 (s, 2H, CH2), 1.38 (br s, 3H, CH3). 19F NMR (CD3CN): δ = −81.2 (m,
2
6F, CF3), −121.9 (m, 2F, CFa), −124.3 (m, 2F, CFb), 2JPFa = 73.6 Hz, JPFb = 88.2 Hz,
2
2
2JFaFb = 320.4 Hz. 31P NMR (CD3CN): δ = 9.2 (quint of d, JPF = 76.0 Hz, JPH
=
39.3 Hz). For C18H23N2F10O2P: Calcd: C 41.55; H 4.46; N 5.38; Found: C 38.99; H 4.45;
N 6.34%.
CONCLUSION
The reactions of bis(pentafluoroethyl)phosphinyl chloride or tris(pentafluoroethyl)-
phosphine oxide with primary amines or hydrazines result in the formation of the corre-
sponding bis(pentafluoroethyl)phosphinyl amides or hydrazides in good yields.
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