Solid state and solution study of some phosphoramidate derivatives containing the P(O)NHC(O) bifunctional group: Crystal structures of CCl2HC(O)NHP(O)(NCH3(CH2C6 H5))2, p-ClC6H<s

Article abstract of DOI:10.1016/j.saa.2009.12.033

Synthetic methods for several novel phosphoramidate compounds containing the P(O)NHC(O) bifunctional group were developed. These compounds with the general formula R₁C(O)NHP(O)(N(R₂)(CH₂C₆ H₅))_2<

Full text of DOI:10.1016/j.saa.2009.12.033

Spectrochimica Acta Part A 75 (2010) 1236–1243
Contents lists available at ScienceDirect
Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy
journal homepage: www.elsevier.com/locate/saa
Solid state and solution study of some phosphoramidate derivatives containing
the P(O)NHC(O) bifunctional group: Crystal structures of
CCl2HC(O)NHP(O)(NCH3(CH2C6H5))2, p-ClC6H4C(O)NHP(O)(NCH3(CH2C6H5))2,
CCl2HC(O)NHP(O)(N(CH2C6H5)2)2 and p-BrC6H4C(O)NHP(O)(N(CH2C6H5)2)2
Saeed Dehghanpoura,∗, Richard Welterb, Aliou Hamady Barryc, Farzaneh Tabasia
a Department of Chemistry, Alzahra University, Vanak, Tehran, Iran
b Laboratoire DECMET, UMR CNRS 7513, Universiteˇı Louis Pasteur, Strasbourg, France
c Deˇıpartement de Chimie, Faculteˇı des Sciences et Techniques, Universiteˇı de Nouakchott, Nouakchott, Mauritania
a r t i c l e i n f o
a b s t r a c t
Article history:
Synthetic
methods
for
several
novel
phosphoramidate
compounds
containing
the
Received 21 October 2009
Received in revised form
23 November 2009
P(O)NHC(O) bifunctional group were developed. These compounds with the general formula
R1C(O)NHP(O)(N(R2)(CH2C6H5))2, where R1 = CCl2H, p-ClC6H4, p-BrC6H4, o-FC6H4 and R2 = hydrogen,
methyl, benzyl, were characterized by several spectroscopic methods and analytical techniques.
The effects of phosphorus substituents on the rotation rate around the P–Namine bond were also
investigated. 1H NMR study of the synthesized compounds demonstrated that the presence of bulky
groups attached to the phosphorus center and electron withdrawing groups in the amide moi-
ety lead to large chemical-shift non-equivalence (ꢀıH) of diastereotopic methylene protons. The
crystal structures of CCl2HC(O)NHP(O)(NCH3(CH2C6H5))2, p-ClC6H4C(O)NHP(O)(NCH3(CH2C6H5))2,
CCl2HC(O)NHP(O)(N(CH2C6H5)2)2 and p-BrC6H4C(O)NHP(O)(N(CH2C6H5)2)2 were determined by
X-ray crystallography using single crystals. The coordination around the phosphorus center in these
compounds is best described as distorted tetrahedral and the P(O) and C(O) groups are anti with
respect to each other. In the compound Br-C6H4C(O)NHP(O)(N(CH2C6H5)2)2 (with two independent
molecules in the unit cell), two conformers are connected to each other via two different N–H· · ·O
hydrogen bonds forming a non-centrosymmetric dimer. In the crystalline lattice of other compounds,
the molecules form centrosymmetric dimers via pairs of same N–H· · ·O hydrogen bonds. The structure
of CCl2HC(O)NHP(O)(N(CH2C6H5)2)2 reveals an unusual intramolecular interaction between the oxygen
of C O group and amine nitrogen.
Accepted 8 December 2009
Keywords:
Phosphoramidate
Synthesis
Structure
Spectroscopic properties
© 2010 Elsevier B.V. All rights reserved.
1. Introduction
compounds containing the P(O)NHC(O) bifunctional group incor-
porating both phosphoryl-nitrogen and carbonyl-nitrogen bonds
There has been a growing interest in the synthesis and charac-
terization of phosphoramidate compounds due to their potential
applications as acetylcholinesterase and urease inhibitors, antiox-
idants, antirust additives in lubricating oils, pesticides, and
anticancer drugs [1–4]. The three or two nitrogen subunits of
these compounds provide the opportunity for a large number
of structurally diverse analogues and hence a broad spectrum
of properties and shapes can be customized [5,6]. Most of these
studies refer to four-coordinated compounds of the P(O)R3 type,
where R is a substituted amine, phenol or alkyl group. Con-
siderably less attention has been devoted to phosphoramidate
[7–13]. These compounds have drawn special attention because
of the biological behavior of ␤-diketophosphonate system [14–17]
and bidentate O, O-donor chelating ligands for metal ions, partic-
ularly for lanthanides [18–27]. Factors such as steric, electronic,
and conformational interactions influence the biochemical activity
and type of complexation reactions of these compounds [16–20].
The phosphorus substituents may modify the steric and electronic
interactions and tune the physical and chemical properties of phos-
phoramidate compounds. A thorough knowledge of the spectral
and structural properties of the phosphoramidate should be bene-
ficial to a detailed understanding of their effect on the properties of
these compounds. Our interest in the chemistry of phosphorami-
date derivatives was stimulated to explore how the variations in
the phosphorus substituents influence the structural and spectral
properties of these compounds.
∗
Corresponding author. Tel.: +98 021 88041344; fax: +98 021 88041344.
E-mail address: Dehganpour farasha@yahoo.com (S. Dehghanpour).
1386-1425/$ – see front matter © 2010 Elsevier B.V. All rights reserved.
doi:10.1016/j.saa.2009.12.033

S. Dehghanpour et al. / Spectrochimica Acta Part A 75 (2010) 1236–1243
1237
2.2.2. N,N,Nꢀ,Nꢀ-benzyl-Nꢀꢀ-(4-bromobenzoyl)-phosphoric
diamide (2a)
This compound was prepared by a procedure similar to that
used for 1a employing (0.4 g, 1.3 mmol) of compound 2, and (0.27 g,
1.3 mmol) of benzylamine. Yield: 91%, mp 188–191 ◦C. Anal. Calc.
for C21H21BrN3O2P: C, 55.04; H, 4.62; N, 9.17; found: C, 55.06;
H, 4.61; N, 9.18. 1H NMR (CDCl3): ı = 3.47 (m, 2H, NH), 4.17 (d,
2JPH = 9.6 Hz, 4H, CH2), 7.15–7.86 (m, 14H, Ar–H), 8.85 (b, 1H, NH).
1
2
13C { H} NMR (CDCl3): ı = 45.91 (d, JPC = 7.2 Hz, CH2), 126.94 (s),
128.10 (s), 128.46 (s), 128.94 (s), 129.04 (s), 130.43 (s), 131.70
(s), 133.84 (s), 141.49 (d, JPC = 4.9), 167.43 (s). 31P { H} NMR
(CDCl3): ı = 9.21 (s). IR (KBr, cm−1): 3415 (m), 3050 (w), 2910 (w),
1666 (s), 1605 (w), 1521 (w), 1446 (vs), 1193 (s), 1005 (m), 799
(s).
2
1
Scheme 1.
Herein, some phosphoramidate derivatives were synthesized
and characterized by 1H, 13C, 31P NMR and IR spectroscopy
and elemental analysis (Scheme 1). In candidate molecules, dif-
ferent behaviors of benzylic proton were studied. Furthermore,
2.2.3. N,N,Nꢀ,Nꢀ-benzyl-Nꢀꢀ-(4-chlorobenzoyl)-phosphoric
diamide (3a)
2
two bond distance-coupling constants; JPN(CH of 1b–4b were
)
2
This compound was prepared by a procedure similar to that
used for 1a employing (0.4 g, 1.5 mmol) of compound 3, and (0.37 g,
1.5 mmol) of benzylamine. Yield: 65%, mp 187–190 ◦C. Anal. Calc.
for C21H21ClN3O2P: C, 60.95; H, 5.11; N, 10.15; found: C, 60.92;
H, 5.10; N, 10.14. 1H NMR (CDCl3): ı = 4.04 (m, 4H, CH2), 5.15 (m,
2
compared to JPN(CH ). The experimental IR spectra of these
3
compounds were studied and the main absorption bands of
similar compounds were assigned. Finally, the structures of
compounds 1b, 3b, 1c and 2c were determined by X-ray crys-
tallography. Combined crystallographic and spectroscopic types
2H, NH), 7.11–7.78 (m, 14H, Ar–H), 8.91 (b, 1H, NH). 13C { H}
1
of evidence were presented for the intramolecular N· · ·O
C
NMR (CDCl3): ı = 46.85 (d, 2JPC = 6.1 Hz, CH2), 127.01 (s), 127.99 (s),
interaction between the benzylic nitrogen and the carbonyl
group.
128.55 (s), 128.92 (s), 129.06 (s), 130.22 (s), 130.74 (s), 133.99 (d,
2
1
2JPC = 5.4), 142.49, 142.66, 169.54 (d, JPC = 3.6, CO). 31P { H} NMR
(CDCl3): ı = 9.01 (s). IR (KBr, cm−1): 3402 (m), 3041 (w), 2920 (w),
1652 (s), 1621 (w), 1531 (m), 1445 (vs), 1188 (s), 1008 (m), 785
(s).
2. Experimental
2.1. Materials and physical measurements
2.2.4. N,N,Nꢀ,Nꢀ-benzyl-Nꢀꢀ-(2-fluorobenzoyl)-phosphoric diamide
(4a)
Compounds RC(O)NHP(O)Cl2, (R = CHCl2, 1; p-Br-C6H4, 2; p-Cl-
C6H4, 3; o-F-C6H4, 4) were prepared by published methods [12].
Melting points were determined on a Gallenkamp apparatus. 1H,
13C and 31P NMR spectra were recorded on a Bruker (Avance DRS
500 MHz spectrometer) (298 K). 31P, 1H and 13C chemical shifts
were determined relative to 85% H3PO4 and TMS, respectively, as
external standards. IR spectra (KBr) were obtained using a Shi-
madzu, IR-60-model spectrophotometer. Elemental analyses were
performed using a Heraeus CHN-O-RAPID. Other compounds used
in the syntheses were obtained from Aldrich Chemical Co. and used
without further purification. All solvents were dried and distilled
before use.
This compound was prepared by a procedure similar to that
used for 1a employing (0.4 g, 1.6 mmol) of compound 4, and (0.34 g,
1.6 mmol) of benzylamine. Yield: 60%, mp 185–198 ◦C. Anal. Calc.
for C21H21FN3O2P: C, 63.47; H, 5.33; N, 10.57; found: C, 63.46; H,
5.30; N, 10.48. 1H NMR (CDCl3): ı = 4.17 (b, 4H, CH2), 5.05 (b, 2H,
1
NH), 7.19 (m, 14H, Ar–H), 8.94 (b, 1H, NH). 13C { H} NMR (CDCl3):
2
ı = 44.21 (d, JPC = 6.1 Hz, CH2), 126.98 (s), 127.70 (s), 128.49 (s),
2
129.29 (s), 130.56 (s), 133.43 (s), 141.49 (d, JPC = 5.9), 141.56 (s),
1
166.13 (s). 31P { H} NMR (CDCl3): ı = 8.18 (s). IR (KBr, cm−1): 3411
(m), 3039 (w), 2901 (w), 1669 (s), 1614 (w), 1509 (w), 1449 (vs),
1184 (s), 1011 (m), 801 (s).
2.2. Preparations of the compounds
2.2.5. N,Nꢀ-benzyl-N,Nꢀ-metyl-Nꢀꢀ-(dichloroacetyl)-phosphoric
triamide (1b)
2.2.1. N,N,Nꢀ,Nꢀ-benzyl-Nꢀꢀ-(dichloroacetyl)-phosphoric triamide
(1a)
A solution of 1 (0.4 g, 1.7 mmol) in chloroform was added to
a solution of methylbenzylamine (0.4 g, 1.7 mmol) in dry chloro-
form (100 mL) at 0 ◦C. The reaction mixture was stirred for 10 h.
The volatile material was removed using a rotary evaporator and
the residue obtained was washed with water (3× 100 mL) and dried
at reduced pressure. The pure product was obtained after recrys-
tallization from an ethanol/n-hexane mixture (3:1). Yield: 90%, mp
201–203 ◦C. Anal. Calc. for C18H22Cl2N3O2P: C, 52.19; H, 5.35; N,
10.14; found: C, 52.12; H, 5.37; N, 10.21. 1H NMR (CDCl3): ı = 2.68
(d, 3JP–H = 10.5 Hz, 6H, CH3), 4.12 (dd, 2JHH = 15.4 Hz, 3JPH = 10.2 Hz,
A solution of 1 (0.4 g, 1.7 mmol) in acetonitrile (50 mL) was
added dropwise to (0.36 g, 1.7 mmol) benzylamine in acetonitrile
in N2 atmosphere at −15 ◦C. The reaction mixture was stirred for
3 h, accompanied by precipitation of a white solid. The solution
was filtered and the crude product was washed with water (3×
100 mL) and n-hexane (2× 100 mL) and dried in vacuo. The pure
product was obtained after recrystallization from a chloroform/n-
heptane mixture (5:1). Yield: 88%, mp 182–184 ◦C. Anal. Calc. for
C
16H18Cl2N3O2P: C, 49.76; H, 4.70; N, 10.88; found: C, 49.80; H,
2
3
4.64; N, 10.93. 1H NMR (CDCl3): ı = 4.03 (m, 4H, CH2), 5.93 (m, 2H,
2H, CH2), 4.26 (dd, JHH = 15.4 Hz, JPH = 10.2 Hz, 2H, CH2), 6.30 (s,
NH), 5.97 (d, JPH = 4.9 Hz, 1H, CH), 7.26–7.34 (m, 5H, Ar–H), 8.86
1H, CH), 7.27–7.41 (m, 10H, 2Ar–H), 9.99 (b, 1H, NH). 13C { H}
2
1
(b, 1H, NH). 13C { H} NMR (CDCl3): ı = 44.8 (d, JPC = 6.7 Hz, CH2),
NMR (CDCl3): ı = 33.55 (d, 2JPC = 5.3 Hz, CH3), 52.95 (d, 2JPC = 6.9 Hz,
CH2), 66.7 (d, JPC = 12.5 Hz), 127.5 (s), 128.1 (s), 128.6 (s), 137.2 (d,
1
2
66.35 (d, 2JPC = 5.33 Hz, CH), 127.4 (s), 127.5 (s), 127.7 (s), 139.05 (d,
JPC = 7.1 Hz), 165.5 (d, 2JPC = 4.1, CO). 31P { H} NMR(CDCl3): ı = 15.59
1
1
JPC = 6.1 Hz), 165.9 (d, 2JPC = 3.6, CO). 31P { H} NMR (CDCl3): ı = 8.05
(s). IR (KBr, cm−1): 3396 (m), 3020 (w), 2915 (w), 1714 (s), 1452
(vs), 1208 (s), 1008 (m), 834 (s).
(s). IR (KBr, cm−1): 3411 (m), 3030 (w), 2932 (w), 1711 (s), 1444 (vs),
1185 (s), 1017 (m), 855 (s).

1238
S. Dehghanpour et al. / Spectrochimica Acta Part A 75 (2010) 1236–1243
2.2.6. N,Nꢀ-dibenzyl-N,Nꢀ-dimetyl-Nꢀꢀ-(4-bromobenzoyl)-
phosphoric diamide (2b)
(CDCl3): ı = 15.59 (s). IR (KBr, cm−1): 3409 (m), 3024 (w), 2919 (w),
1719 (s), 1440 (vs), 1172 (s), 1019 (m), 821 (s).
This compound was prepared by a procedure similar to that
used for 1b employing (0.4 g, 1.3 mmol) of compound 2, and (0.3 g,
1.3 mmol) of benzylmethylamine. Yield: 82%, mp 210–212 ◦C. Anal.
Calc. for C35H33BrN3O2P: C, 65.83; H, 5.21; N, 6.58; found: C, 65.80;
2.2.10. N,N,Nꢀ,Nꢀ-dibenzyl-Nꢀꢀ-(4-bromobenzoyl)-phosphoric
diamide (2c)
3
H, 5.21; N, 6.55. 1H NMR (CDCl3): ı = 2.52 (d, JPH = 9.3 Hz, 6H,
This compound was prepared by a procedure similar to that
used for 1c employing (0.4 g, 1.3 mmol) of compound 2, and (0.5 g,
1.3 mmol) of dibenzylamine. Yield: 67%, mp 242–245 ◦C. Anal. Calc.
for C35H33BrN3O2P: C, 65.83; H, 5.21; N, 6.58; found: C, 65.80;
2
3
CH3), 4.11 (dd, JHH = 15.3 Hz, JPH = 10.6 Hz, 2H, CH2), 4.18 (dd,
2JHH = 15.3 Hz, JPH = 10.6 Hz, 2H, CH2), 7.17–7.81 (m, 24H, Ar–H),
3
9.18 (s, 1H, NH). 13C { H} NMR (CDCl3): ı = 33.85 (d, JPC = 4.1 Hz,
CH3), 55.96 (d, 2JPC = 6.8 Hz, CH2), 127.3 (s), 128.5 (s), 129.8 (s), 131.7
(s), 132.4 (s), 132.6 (s), 136.8 (d, JPC = 5.8 Hz), 137.9 (s), 167.6 (d,
1
2
2
H, 5.21; N, 6.55. 1H NMR (CDCl3): ı = 4.06 (dd, JHH = 15.5 Hz,
3JPH = 10.2 Hz, 2H, CH2), 4.28 (dd, 2JHH = 15.5 Hz, 3JPH = 10.2 Hz, 2H,
1
CH2), 7.17–7.81 (m, 24H, 5Ar–H), 9.18 (s, 1H, NH). 13C { H} NMR
2JPC = 2.5, CO). 31P { H} NMR (CDCl3): ı = 16.71 (s). IR (KBr, cm−1):
1
2
(CDCl3): ı = 49.05 (d, JPC = 6.3 Hz), 127.3 (s), 128.4 (s), 128.7 (s),
3392 (m), 3018 (w), 2927 (w), 1662 (s), 1617 (w), 1489 (w), 1441
(vs), 1177 (s), 1015 (m), 794 (s).
129.8 (s), 131.7 (s), 132.4 (s), 132.6 (s), 136.8 (d, JPC = 5.9), 136.9,
167.6 (d, 2JPC = 2.3, CO). 31P { H} NMR(CDCl3): ı = 16.71 (s). IR (KBr,
1
cm−1): 3398 (m), 3011 (w), 2905 (w), 1665 (s), 1610 (w), 1510 (w),
1444 (vs), 1175 (s), 1023 (m), 804 (s).
2.2.7.
N,Nꢀ-dibenzyl-N,Nꢀ-dimetyl-Nꢀꢀ-(4-chlorobenzoyl)-phosphoric
diamide (3b)
This compound was prepared by a procedure similar to that
used for 1b employing (0.4 g, 1.5 mmol) of compound 3, and (0.4 g,
1.5 mmol) of benzylmethylamine. Yield: 86%, mp 207–210 ◦C. Anal.
Calc. for C23H25ClN3O2P: C, 62.51; H, 5.70; N, 9.51; found: C, 62.54;
H, 5.72; N, 9.47. 1H NMR (CDCl3): ı = 2.69 (d, 6H, JPH = 10.3 Hz,
2.2.11. N,N,Nꢀ,Nꢀ-dibenzyl-Nꢀꢀ-(4-chloro benzoyl)-phosphoric
diamide (3c)
This compound was prepared by a procedure similar to that
used for 1c employing (0.4 g, 1.5 mmol) of compound 3, and (0.7 g,
1.5 mmol) of dibenzylamine. Yield: 93%, mp 245–247 ◦C. Anal. Calc.
for C35H33ClN3O2P: C, 70.76; H, 5.60; N, 7.07; found: C, 70.77;
2
3
2CH3), 4.18 (dd, JHH = 15.2 Hz, JPH = 10.1 Hz, 2H, CH2), 4.27 (dd,
2JHH = 15.2 Hz, 3JPH = 10.1 Hz, 2H, CH2), 7.22–8.00 (m, 14H, 3Ar–H),
H, 5.60; N, 7.04. 1H NMR (CDCl3): ı = 4.32 (dd, JHH = 15.4 Hz,
2
1
2
9.11 (b, 1H, NH). 13C { H} NMR (CDCl3): ı = 33.85 (d, JPC = 6.1 Hz,
CH3), 53.05 (d, 2JPC = 6.8 Hz), 127.3 (s), 128.1 (s), 128.7 (s), 129.8 (d,
JPC = 3.2 Hz), 131.8 (s), 138.9 (s), 137.8 (s), 138.8 (s), 167.7 (s, CO).
3JPH = 10.3 Hz, 2H, CH2), 4.53 (dd, 2JHH = 15.4 Hz, 3JPH = 10.3 Hz, 2H,
1
CH2), 7.18–7.84 (m, 24H, m, 5Ar–H), 8.89 (b, 1H, NH). 13C { H} NMR
2
(CDCl3): ı = 49.15 (d, JPC = 6.6 Hz), 127.3 (s), 128.4 (s), 128.7 (s),
31P { H} NMR (CDCl3): ı = 16.39 (s). IR (KBr, cm−1): 3414 (m), 3071
1
129.6 (s), 131.4 (s), 132.6 (s) 136.9 (s), 138.8 (d, JPC = 3.9 Hz), 167.5
(w), 2909 (w), 1669 (s), 1611 (w), 1541 (m), 1449 (vs), 1173 (s),
1022 (m), 802 (s).
1
(s). 31P { H} NMR (CDCl3): ı = 16.60 (s). IR (KBr, cm−1): 3405 (m),
3101 (w), 2933 (w), 1666 (s), 1637 (w), 1545 (m), 1441 (vs), 1169
(s), 1028 (m), 812 (s).
2.2.8. N,Nꢀ-dibenzyl-N,Nꢀ-dimetyl-Nꢀꢀ-(2-fluoro
benzoyl)-phosphoric diamide (4b)
2.2.12. N,N,Nꢀ,Nꢀ-dibenzyl-Nꢀꢀ-(2-fluoro benzoyl)-phosphoric
diamide (4c)
This compound was prepared by a procedure similar to that
used for 1b employing (0.4 g, 1.6 mmol) of compound 4, and (0.38 g,
1.6 mmol) of benzylmethylamine (0.38 g, 1.6 mmol). Yield: 81%, mp
215–219 ◦C. Anal. Calc. for C23H25FN3O2P: C, 64.93; H, 5.92; N,
9.88; found: C, 64.95; H, 5.90; N, 9.88. 1H NMR (CDCl3): ı = 2.71 (d,
This compound was prepared by a procedure similar to that
used for 1c employing (0.4 g, 1.6 mmol) of compound 4, and (0.38 g,
1.6 mmol) of dibenzylamine. Yield: 94%, mp 239–243 ◦C. Anal. Calc.
for C35H33FN3O2P: C, 72.78; H, 5.76; N, 7.27; found: C, 72.76;
2
3
6H, JPH = 10.41, 2CH3), 4.36 (dd, JHH = 15.7 Hz, JPH = 10.2 Hz, 2H,
2
3
2
H, 5.76; N, 7.22. 1H NMR (CDCl3): ı = 4.34 (dd, JHH = 15.1 Hz,
CH2), 4.46 (dd, JHH = 15.7 Hz, JPH = 10.2 Hz, 2H, CH2), 7.12–8.03
(m, 14H, 3Ar–H). 13C { H} NMR (CDCl3): ı = 33.71 (d, 2JPC = 4.83 Hz,
1
3JPH = 10.5 Hz, 2H, CH2), 4.49 (dd, 2JHH = 15.1 Hz, 3JPH = 10.5 Hz, 2H,
CH3), 53.05 (d, 2JPC = 5.43 Hz, CH2), 120.85 (s), 121.00 (s), 124.95 (s),
127.29 (s), 128.52 (s), 131.93 (s), 134.52 (s), 137.70 (d, JPC = 5.4 Hz),
1
CH2), 7.11–7.88 (m, 24H, 5Ar–H). 13C { H} NMR (CDCl3): ı = 49.02
(d, 2JPC = 7.1 Hz), 127.28 (s), 128.40 (s), 128.79 (s), 129.94 (s) 132.11
162.37 (d, 2JPC = 2.2 Hz, CO). 31P { H} NMR (CDCl3): ı = 15.43 (s). IR
1
1
(s), 136.65 (s), 136.70 (d, JPC = 6.3 Hz), 166.12 (s). 31P { H} NMR
(KBr, cm−1): 3401 (m), 3005 (w), 2928 (w), 1661 (s), 1624 (w), 1522
(w), 1440 (vs), 1169 (s), 1029 (m), 811 (s).
(CDCl3): ı = 15.50 (s). IR (KBr, cm−1): 3409 (m), 3055 (w), 2930 (w),
1669 (s), 1611 (w), 1492 (w), 1440 (vs), 1167 (s), 1042 (m), 799 (s).
2.2.9. N,N,Nꢀ,Nꢀ-dibenzyl-Nꢀꢀ-(dichloroacetyl)-phosphoric
2.3. X-ray crystallography analyses
triamide (1c)
A solution of (0.4 g, 1.7 mmol) 1 in chloroform (50 mL) was added
dropwise to a solution of dibenzylamine (0.7 g, 1.7 mmol) in dry
chloroform (100 mL). The colorless solution obtained was cooled to
−10 ◦C and maintained at that temperature for 30 min. The −10 ◦C
bath was then removed and the solution was refluxed for 48 h.
Volatiles were removed using a rotary evaporator and the remain-
ing crude solid was washed with water (3× 100 mL) and dried in
vacuo. The pure product was obtained after recrystallization from
a chloroform/n-heptane mixture (5:1). Yield: 65%, mp 236–239 ◦C.
Anal. Calc. for C30H30Cl2N3O2P: C, 63.61; H, 5.34; N, 7.42; found: C,
63.60; H, 5.34; N, 7.46. 1H NMR (CDCl3): ı = 4.42 (dd, 2JHH = 15.62 Hz,
3JPH = 7.8 Hz, 2H, CH2), 4.47 (dd, 2JHH = 15.62 Hz, 3JPH = 10.2 Hz, 2H,
CH2), 6.13 (s, 1H, CH), 7.21–7.33 (m, 20H, 4Ar–H), 9.32 (b, 1H, NH).
Single crystals of 1b, 3b, 1c and 2c were obtained from a solu-
tion of chloroform and hexane (4:1 ratio) at room temperature.
Data collection and refinement parameters are listed in Table 1.
Single crystals were mounted on a Nonius Kappa-CCD area detec-
tor diffractometer (Mo K␣ ꢁ = 0.71073 Å). The complete conditions
of data collection (Denzo software) and structure refinements are
given below. The cell parameters were determined using reflec-
tions taken from one set of 10 frames (1.0◦ steps in phi angle), each
at 20 s exposure. The structures were solved using direct methods
(SHELXS97) and refined against F2 using the SHELXL97 software
[28]. The absorptions were not corrected. All non-hydrogen atoms
were refined anisotropically. Hydrogen atoms were generated
according to stereochemistry and refined using a riding model in
SHELXL97.
13C { H} NMR (CDCl3): ı = 48.9 (d, 2JPC = 6.3 Hz, CH2), 66.6 (s), 127.5
1
1
(s), 128.5 (s), 128.7 (s), 136.2 (d, JPC = 6.1 Hz), 164.8 (s). 31P { H} NMR

S. Dehghanpour et al. / Spectrochimica Acta Part A 75 (2010) 1236–1243
1239
Table 1
Structures determination summary of 1b, 3b, 1c and 2c.
1b
3b
1c
2c
Formula
Formula weight
Wavelength (Å)
Crystal system
Space group
a (Å)
C18H22Cl2N3O2P
414.26
0.71073
Triclinic
P-1
9.832(2)
10.842(2)
11.139(3)
69.856(13)
66.929(10)
72.696(11)
1007.3(4)
2
C23H25Cl N3O2P
441.88
0.71073
Monoclinic
P21/n
9.04400(10)
13.0320(2)
19.4430(3)
90.00
94.7380(8)
90.00
2283.75(6)
4
1.285
0.261
928
C30H30Cl2N3O2P
566.44
0.71073
Monoclinic
P21/n
11.3580(3)
16.4560(4)
15.3540(4)
90.00
93.2520(12)
90.00
2865.15(13)
4
1.313
0.315
C35H33BrN3O2P
638.52
0.71073
Monoclinic
P21/n
16.56200(10)
19.4860(2)
19.2600(2)
90.00
99.3530(6)
90.00
6133.09(10)
8
1.383
1.429
2640
b (Å)
c (Å)
˛ (◦)
ˇ (◦)
ꢂ (◦)
V (A3)
Z
Density (g cm−3
)
1.366
0.42
432
ꢃ (mm−1
F (000)
)
1184
Crystal size
Theta range for data
collection
0.10 × 0.10 × 0.10
0.10 × 0.10 × 0.10
0.15 × 12 × 0.10
0.10 × 0.10 × 0.10
0.994–30.01
1.88–30.08
1.82–30.01
Index ranges
−13 ≤ h ≤ 13,
−15 ≤ k ≤ 14,
−15 ≤ l ≤ 15
5860
−12 ≤ h ≤ 12,
−18 ≤ k ≤ 16,
−27 ≤ l ≤ 27
6688
−15 ≤ h ≤ 10,
−23 ≤ k ≤ 20,
−21 ≤ l ≤ 21
8323
−23 ≤ h ≤ 23,
−27 ≤ k ≤ 25,
−26 ≤ l ≤ 27
17912
Reflections collected
Independent reflections
3702 [R (int) = 0.05]
4318 [R
4152 [R
11814 [R
(int) = 0.074]
4318/0/271
1.043
R1 = 0.0570,
wR2 = 0.1489
R1 = 0.0931,
wR2 = 0.1699
0.000, 0.000
(int) = 0.067]
4152/0/343
0.956
R1 = 0.0588,
wR2 = 0.1437
R1 = 0.1370,
wR2 = 0.1785
0.001, 0.000
(int) = 0.074]
11814/0/757
1.007
R1 = 0.0577,
wR2 = 0.1189
R1 = 0.1002,
wR2 = 0.1355
0.002, 0.000
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices
[I > 2sigma(I)]
R indices (all data)
3702/0/235
1.038
R1 = 0.0489,
wR2 = 0.1193
R1 = 0.1373,
wR2 = 0.0890
0.000, 0.000
Maximum and average
shift/error
Largest diff. peak and
−0.40, 0.35
−0.619, 0.204
−0.558, 0.331
−1.026, 1.067
hole (e Å−3)
3. Results and discussion
3.1. Spectral study
As indicated in Scheme 2, a series of phosphoramidates were
synthesized with various amide and amine moieties based on PCl5
as a common starting material. The synthesis of these compounds
is accomplished via elimination of HCl. In an attempt to avoid an
acidic system, an excess of amine was added to the reaction mix-
tures.
Structural assignment of the synthesized compounds (1a–4a,
1b–4b and 1c–4c) can be carried out using 1H, 31P and 13C NMR
spectroscopy. A summary of the NMR data of these compounds
is given in Table 2. The different behaviors exhibited by ben-
zylic protons for some synthesized compounds are presented in
Fig. 1.
Table 2
Some 1H and 13C NMR parameters of synthesized compounds.
.
R1
R2
␦CH2
3JPNCH
2JHH
␦CH3
2JP–CH
␦CH2
2JP–CH
␦CO
3
2
1a
2a
3a
4a
1b
2b
3b
4b
1c
2c
3c
4c
CCl2H
H
H
H
H
CH3
CH3
CH3
CH3
CH2C6H5
CH2C6H5
CH2C6H5
CH2C6H5
4.03
4.17
4.04
4.17
4.09–4.28
4.08–4.21
4.16–4.29
4.34–4.48
4.13–4.49
4.04–4.31
4.30–4.55
4.32–4.51
–
9.6
–
–
10.2
10.5
10.1
10.2
7.8, 10.2
10.2
10.3
10.5
–
–
–
–
15.4
15.3
15.2
15.7
15.6
15.5
15.4
15.1
–
–
–
–
–
–
–
–
5.3
4.1
6.1
4.8
–
44.8
45.9
46.8
44.2
52.9
53.1
53.1
53.1
48.9
49.1
49.2
49.1
6.7
7.2
6.1
6.1
6.9
6.8
6.9
5.4
6.3
6.3
6.6
7.1
165.9
167.4
169.5
166.1
165.5
167.5
167.7
162.3
164.8
167.6
167.5
166.1
p-Br-C6H4
p-Cl-C6H4
o-F-C6H4
CCl2H
p-Br-C6H4
p-Cl-C6H4
o-F-C6H4
CCl2H
33.6
33.9
33.9
33.7
–
–
–
p-Br-C6H4
p-Cl-C6H4
o-F-C6H4
–
–
–
–

1240
S. Dehghanpour et al. / Spectrochimica Acta Part A 75 (2010) 1236–1243
The diastereotopic benzylic protons in synthesized compounds
exhibit splitting by the phosphorus atom, 3JPNCH, followed by 2JHH
(geminal) splitting. However, as shown in Fig. 1, these protons
appear as doublets, multiplets, and two doublets of doublets.
The benzylic protons in 1b–4b and 1c–4c show two
doublets of doublets with
equivalence (ꢀıH = 0.13–0.36)
a
large chemical-shift non-
and N-acetyl derivatives
(CCl2H–C(O)NHP(O)(R2)2) with same amine groups have the
greatest values of chemical-shift non-equivalence. The 1H NMR
spectra of 1a, 3a and 4a with benzylamine substituents reveal
a multiplet for the benzylic protons. This means that the two
separate signals are coalesced with each other due to the inter-
mediate rotation rate around the P–N bond. However, compound
3
2a shows only a doublet produced by a JPNCH coupling constant.
When the rotational energy barrier around the P–N bond is low,
benzylic protons appear with equal chemical shifts on the NMR
scale. It can be suggested that this behavior of benzylic protons
in the synthesized compounds depends on the degree of steric
effect of phosphorus substituents (presence of bulky groups in
the phosphorus center) and electronic effect of amide moiety
(with influence on the P–Namine bond lengths). The P–Namine bond
lengths for 1b and 1c containing electron withdrawing groups in
amide moiety (chlorine atoms) are slightly shorter than those in
N-benzoyl derivatives (3b and 2c) (vide infra). It is of interest to
note that the 1H NMR spectrum of 1c recorded in chloroform shows
a remarkably large chemical-shift non-equivalence (ꢀıH = 0.36) of
the benzylic protons (Fig. 1). In addition to steric and electronic
effects, this result may be a consequence of the retention of the
intramolecular C O· · ·N interaction upon the transfer of 1c from
the solid state to the solution (vide infra).
3
In compound 1c, the JPNCH values obtained for the individual
protons of the benzylic CH2 group are different, indicating dif-
ferent angular relationship within the fragments P–N–C–HA and
P–N–C–HB, which can be retained in solution because of the highly
restricted rotation about the P–N bonds. Each of the diastereotopic
benzylic protons gives rise to doublets of doublets with a 2JHH (gem-
inal) constant of 15.6 Hz, while 3JPNCH values of 7.8 Hz and 10.2 Hz
are obtained.
2
The phosphorus–hydrogen coupling constants, JPNH for the
amide nitrogen in the intermediate compounds (1–4) are about
11 Hz [12]. However, replacement of chlorine substituents by the
2
amine groups decreases the JPNH values for the amide nitro-
2
gen. In the 1HNMR spectra of the synthesized compounds, JPNH
values for amidic proton are not observed. These observations indi-
cate p –d interaction between the phosphorus atom and amine
␲
␲
groups.
13C NMR spectra show that methylene and methyl carbon
atoms in compounds 1b–4b appear in the 52.95–53.05 range and
33.55–33.85 ppm, respectively (Table 2). The presence of phenyl
groups linked to CH2 may cause deshielding of the CH2 carbon
atoms relative to the CH3 carbon atoms. The deshielding of methy-
lene groups leads to a greater interaction with the corresponding
Fig. 1. 1H NMR spectrum of the benzylic CH2 protons for some synthesized com-
pounds (CDCl3).
phosphorus atoms and thereby 2JPC(CH is greater than 2JPC(CH
.
methylene protons. However, 31P signal in 2a is split only by equiv-
alence methylene hydrogen atoms.
)
)
2
3
31P NMR spectra of selected compounds indicate multiplets
produced by the couplings with H atoms of amine, methyl and
The main absorption bands in the IR spectra of the synthe-
sized compounds, together with their assignments are given in
Table 3. The IR spectra of these compounds exhibit the character-
istic band corresponding to carbonyl group (C O), which appears
in the 1652–1719 cm−1 region. The stretching vibrations of phos-
phoryl group (P O) appear in the 1169–1208 cm−1 region. A shift
to a low frequency region is observed for both phosphoryl and the
carbonyl groups in the N-benzoyl relative to the N-acetyl deriva-
tives. The degree of interaction of the amide and amine nitrogen
atoms with the neighboring phosphoryl centers in 1b, 3b, 1c and
2c can be inferred from X-ray crystallography data. The structure of
these compounds reveals that the P–Namide bond is longer than the
Scheme 2.

S. Dehghanpour et al. / Spectrochimica Acta Part A 75 (2010) 1236–1243
1241
Table 3
Vibrational frequencies (cm−1) in the infrared spectra and their assignments.
Assignment
1a
2a
3a
4a
1b
2b
3b
4b
1c
2c
3c
4c
ꢄ(P O)
ꢄ(C O)
␦(N–H)amide
ꢄ(P–N)amine
ꢄ(P–N)amide
ꢄ(N–H)amide
1208
1714
1452
1008
834
1193
1666
1446
1005
799
1188
1652
1445
1008
785
1184
1669
1449
1011
801
1185
1711
1444
1017
855
1177
1662
1441
1015
794
1173
1669
1449
1022
802
1169
1661
1440
1029
811
1172
1719
1440
1019
821
1175
1665
1444
1023
804
1169
1666
1441
1028
812
1167
1669
1440
1042
799
3396
3415
3402
3411
3411
3392
3414
3401
3409
3398
3405
3409
Table 4
Selected geometrical parameters (Å,◦) for 1b, 3b and 1c with standard uncertainties in parentheses.
1b
3b
1c
Bond lengths (Å)
P1-O1
P1-N1
P1-N2
P1-N3
1.482(1)
1.627(2)
1.629(2)
1.694(2)
1.355(2)
1.205(2)
P1-O2
P1-N3
P1-N2
P1-N1
C7-N1
O1-C7
1.475(1)
1.636(1)
1.642(1)
1.678(1)
1.373(2)
1.221(2)
P1-O1
P1-N1
P1-N2
P1-N3
C29-N3
O2-C29
1.469(2)
1.635(2)
1.640(2)
1.694(2)
1.363(3)
1.213(3)
C17-N3
O2-C17
Bond angles (◦)
O1-P1-N1
O1-P1-N2
N1-P1-N2
O1-P1-N3
N1-P1-N3
N2-P1-N3
C8-N1-C1
C8-N1-P1
C1-N1-P1
C16-N2-C9
C16-N2-P1
C9-N2-P1
C17-N3-P1
C17-N3-H3
P1-N3-H3
109.8(8)
O2-P1-N3
O2-P1-N2
N3-P1-N2
O2-P1-N1
N3-P1-N1
N2-P1-N1
C7-N1-P1
C7-N1-H1
P1-N1-H1
C15-N2-C14
C15-N2-P1
C14-N2-P1
C16-N3-C17
C16-N3-P1
C17-N3-P1
110.2(7)
O1-P1-N1
O1-P1-N2
N1-P1-N2
O1-P1-N3
N1-P1-N3
N2-P1-N3
C8-N1-C1
C8-N1-P1
C1-N1-P1
C15-N2-C22
C15-N2-P1
C22-N2-P1
C29-N3-P1
C29-N3-H3N
P1-N3-H3N
110.3(9)
119.4(8)
105.7(9)
104.2(7)
113.6(9)
104.3(8)
115.0(2)
122.9(1)
120.5(1)
113.6(2)
125.4(2)
119.9(1)
130.4(1)
114.8
118.6 (7)
104.2(7)
105.7(7)
112.9(8)
105.5(7)
128.2 (1)
115.9
119.8(9)
106.6(9)
105.6(8)
111.5(9)
102.9(9)
114.6(2)
124.7(1)
120.1(1)
112.9(2)
119.9(1)
121.6(1)
128.0(2)
116.0
115.9
113.7 (1)
116.6 (1)
122.3(1)
114.3(1)
125.5(1)
120.2(1)
114.8
116.0
P–Namine bond (Table 4). Therefore, the medium absorption band
observed around 785 to 834 cm−1 corresponds to the stretching
vibrations of P–Namide bond while presence of an intense band at
1005–1042 cm−1 is associated with the P–Namine stretching vibra-
tions. This assignment is arrived at by comparing the spectra of
synthesized compounds with those of similar phosphoramidate
molecules [29].
Table 5
Selected geometrical parameters (Å,◦) for 2c1 and 2c2 with standard uncertainties
in parentheses.
2c1
2c2
Bond lengths (Å)
P1-O2
P1-N3
P1-N2
P1-N1
1.479(2) P2-O4
1.643(2) P2-N6
1.647(2) P2-N5
1.692(2) P2-N4
1.221(3) O3-C42
1.372(3) N4-C42
1.483(2)
1.640(2)
1.649(2)
1.691(2)
1.225(3)
1.373(3)
3.2. Structural studies
The molecular structures of 1b, 3b, 1c and 2c with the atom
numbering schemes are presented in Figs. 2–5 and selected inter-
atomic parameters are collected in Tables 4 and 5. As shown in
Fig. 4, compound 2c exists as two independent molecules (2c1 and
2c2) in a crystalline lattice.
The crystal structures of 1b, 3b, 1c and 2c consist of a core
unit containing phosphoryl, nitrogen and carbonyl groups in the
P(O)N(H)C(O)– fashion. In all structures, the P(O) and C(O) groups
are in anti-position with respect to each other.
The coordination environment around the phosphorus atoms of
these compounds is approximately tetrahedral since the average
values of six angles involving P are 109.5◦, 109.5◦, 109.4◦, 109.43◦
and 109.5◦ for 1b, 3b, 1c, 2c1 and 2c2, respectively. However, the
coordination is clearly distorted, arising from the presence of differ-
ent substituents at phosphorus center. For 1b, the angles N2-P1-N3
and O1-P1-N2 are 104.3(8)◦ and 119.4(8)◦, respectively. This is also
the case in 3b, 1c, and 2c.
Amine P–N bonds in all studied compounds (1b 1.63(2) and
1.63(2), 3b 1.64(1) and 1.64(1), 1c 1.64(2) and 1.64(2), 2c1 1.64(2)
and 1.65(2), 2c2 1.64 (2) and 1.65(2) Å) are of interest when com-
pared with the typical P–N bond distance of 1.77 Å [6]. In all
O1-C7
N1-C7
Bond angles (◦)
O2-P1-N3
O2-P1-N2
N3-P1-N2
O2-P1-N1
N3-P1-N1
N2-P1-N1
C7-N1-P1
C7-N1-H1
P1-N1-H1
C15-N2-C8
C15-N2-P1
C8-N2-P1
C22-N3-C29
C22-N3-P1
C29-N3-P1
111.3(1)
O4-P2-N6
O4-P2-N5
N6-P2-N5
O4-P2-N4
N6-P2-N4
N5-P2-N4
C42-N4-P2
C42-N4-H4
P2-N4-H4
C43-N5-C50
C43-N5-P2
C50-N5-P2
C57-N6-C64
C57-N6-P2
C64-N6-P2
110.8(1)
118.0(1)
106.8(9)
104.5(9)
111.0(9)
105.1(1)
127.4(2)
116.3
118.7(9)
106.0(9)
105.1(9)
112.2(9)
104.2(1)
124.9(2)
117.5
116.3
117.5
115.8(2)
118.5(2)
121.8(2)
115.7(2)
124.2(2)
118.9(2)
114.5(2)
118.5(1)
120.4(2)
114.6(2)
125.3(2)
119.5(2)
Torsion angles (◦)
O2-P1-N2-C8
O2-P1-N2-C15
O2-P1-N3-C22
O2-P1-N3-C29
−88.9(2)
67.9(2)
166.4(2)
−0.5 (2)
O4-P2-N5-C43
O4-P2-N5-C50
O4-P2-N6-C57
O4-P2-N6-C64
−71.7(2)
78.0 (2)
−158.8(2)
11.4(2)

1242
S. Dehghanpour et al. / Spectrochimica Acta Part A 75 (2010) 1236–1243
Fig. 4. The hydrogen bonding (NH· · ·O P) and N· · ·O C interaction in the compound
1c with ellipsoid probability of 50% (hydrogen atoms shown as circles of arbitrary
radii).
structures, amine groups are nearly planar as measured by the sums
of three bond angles around nitrogen atoms (ꢅN). Furthermore,
the planarity around the amidic nitrogen is also reflected in the
distances around this atom, being rather shorter than normal P–N
bond (Tables 4 and 5).
The Ph ring and –C–C(O)N– unit connecting the ring in 3b and
2c are coplanar. The angle between the plane of the Ph ring and
the plane subtended by –C–C(O)N– for 3b is 27.1(1) and 30.4(2)
and 18.9(2)◦ for two conformers of 2c. This degree of coplanarity
allows for increased ␲-conjugation between phenyl and amide
groups.
As shown in Fig. 4, the 2c1 and 2c2 are nearly identical in
their distances and angles as well as configurations. The main
distinctions between these conformers exist in the different ori-
entations of the dibenzyl amine group. The difference is described
by comparison of corresponding torsion angles O–P–N–CH2 in two
conformers (Table 5). The various orientations of the dibenzyl
Fig. 2. Crystallogeraphically determined molecular structure of 1b drawn with 50%
probability ellipsoids (hydrogen atoms omitted for clearer view).
Fig. 3. Crystallogeraphically determined molecular structure of 3b drawn with 50%
probability ellipsoids (hydrogen atoms omitted for clearer view).
Fig. 5. The hydrogen bonding in the compound 2c with ellipsoid probability of 50%
(hydrogen atoms shown as circles of arbitrary radii).

S. Dehghanpour et al. / Spectrochimica Acta Part A 75 (2010) 1236–1243
1243
Table 6
Hydrogen bond D–H· · ·A for 1b, 3b, 1c and 3c.
D–H· · ·A
d(D–H)
d(H· · ·A)
d(D· · ·A)
<(DHA)
1b
3b
1c
N3–H3· · ·O1[1 − x, 1 − y, 1 − z]
0.880
0.860
0.860
0.859
0.860
1.912
1.986
1.983
1.994
2.091
2.772
2.835
2.824
2.832
2.927
165.114
169.029
165.223
164.617
163.888
N1–H1· · ·O1[1 − x, 1 − y, 1 − z]
N3–H3N· · ·O1[0.5 + x, 0.5 − y, 0.5 + z]
N1–H1· · ·O4
2c
N4–H4· · ·O2
amine group seem to be greatly influenced by restricted rotation of
the P–N bond in solid state.
no. 704317–704320 for 1b, 1c, 2c and 3b, respectively. Copies of
the data can be obtained free of charge on application to CCDC, 12
Union Road, Cambridge CB2 1EZ, UK (fax: +44 1223 336033; e-mail:
deposit@ccdc.cam.ac.uk or http://www.ccdc.cam.ac.uk).
The crystal structure of 1c reveals N· · ·O C interamolecular
interaction in a five-membered ring (Fig. 5). The N(2)· · ·O(2) = C(29)
distance is 3.066(2) Å, which is slightly shorter than the sum of the
van der Waals radii [30]. The decrease in electron density on the car-
bonyl group by electron withdrawing groups in the amide function
(chlorine atoms) and the highly restricted rotation of the P–Namine
bond, may facilitate the formation of this unusual interaction.
Molecules 1b, 3b and 1c (Fig. 5) form centrosymmetric dimers
in eight-membered rings held together in the crystals by the
>P(O)HN– functional group as a simultaneous hydrogen bonding
donor and acceptor. In 2c, two independent molecules are con-
nected to each other via two different –P O· · ·HN– hydrogen bonds
and form a non-centrosymmetric dimer (Fig. 5). Based on the
parameters shown in Table 6, the hydrogen bonding interactions
for 1b, 3b, 1c and 2c are considerably strong.
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Appendix A. Supplementary data
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