A new solvated phosphoric triamide, [(C 6H 4(3-CH 3)NH) 3P(O)] · (C 2H 5OH): A database analysis of n atom geometry in compounds with an [N] 3P(O) Fragment

Article abstract of DOI:10.1080/10426507.2012.744015

In the crystal structure of the title compound C21H2₄N ₃OP · C₂H₅OH, there are three crystallographically independent phosphoric triamide molecules and three ethanol molecules. The environments of the nitrogen atoms are practically planar. The phosphorus atoms display a distorted tetrahedral environment; the maximum and minimum values of angles are observed for one OPN and one NPN angles, respectively. In this structure, the phosphoramide and ethanol molecules are linked by some different intermolecular OH···O and NH···O hydrogen bonds to form chains. The title solvated compound has been further characterized by IR and ³¹P{¹H}, ¹H and ¹³C NMR spectroscopy. The geometry of the nitrogen atoms in this compound is analyzed and compared with those of analogous structures deposited in the Cambridge Structural Database (CSD; Allen, Acta Cryst. 2002, B58, 380-388).

Full text of DOI:10.1080/10426507.2012.744015

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Phosphorus, Sulfur, and Silicon and the
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A New Solvated Phosphoric Triamide,
[(C6H4(3-CH3)NH)3P(O)] · (C2H5OH): A
Database Analysis of N Atom Geometry in
Compounds with an [N]3P(O) Fragment
Mehrdad Pourayoubi a , Mahnaz Rostami Chaijan a , Zdenka
Padelková b & Aleš Ružicka b
a Department of Chemistry , Ferdowsi University of Mashhad ,
Mashhad , Iran
b Department of General and Inorganic Chemistry, Faculty of
Chemical Technology , University of Pardubice , Pardubice , Czech
Republic
Accepted author version posted online: 15 Nov 2012.Published
online: 08 May 2013.
To cite this article: Mehrdad Pourayoubi , Mahnaz Rostami Chaijan , Zdenka Padelková & Aleš Ružicka
(2013): A New Solvated Phosphoric Triamide, [(C6H4(3-CH3)NH)3P(O)] · (C2H5OH): A Database Analysis
of N Atom Geometry in Compounds with an [N]3P(O) Fragment, Phosphorus, Sulfur, and Silicon and the
Related Elements, 188:1-3, 224-231
To link to this article: http://dx.doi.org/10.1080/10426507.2012.744015
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Phosphorus, Sulfur, and Silicon, 188:224–231, 2013
Copyright ꢀC Taylor & Francis Group, LLC
ISSN: 1042-6507 print / 1563-5325 online
DOI: 10.1080/10426507.2012.744015
A NEW SOLVATED PHOSPHORIC TRIAMIDE,
[(C6H4(3-CH3)NH)3P(O)] · (C2H5OH): A DATABASE
ANALYSIS OF N ATOM GEOMETRY IN COMPOUNDS
WITH AN [N]3P(O) FRAGMENT
Mehrdad Pourayoubi,1 Mahnaz Rostami Chaijan,1
Zdenka Padelkova´,2 and Alesˇ Ruzˇicka2
1Department of Chemistry, Ferdowsi University of Mashhad, Mashhad, Iran
2Department of General and Inorganic Chemistry, Faculty of Chemical
Technology, University of Pardubice, Pardubice, Czech Republic
GRAPHICAL ABSTRACT
Abstract In the crystal structure of the title compound C21H24N3OP · C2H5OH, there are three
crystallographically independent phosphoric triamide molecules and three ethanol molecules.
The environments of the nitrogen atoms are practically planar. The phosphorus atoms display
a distorted tetrahedral environment; the maximum and minimum values of angles are observed
for one O
P N and one N P N angles, respectively. In this structure, the phosphoramide
and ethanol molecules are linked by some different intermolecular O H···O and N H···O
hydrogen bonds to form chains. The title solvated compound has been further characterized
1
by IR and 31P{ H}, 1H and 13C NMR spectroscopy. The geometry of the nitrogen atoms in
this compound is analyzed and compared with those of analogous structures deposited in the
Cambridge Structural Database (CSD; Allen, Acta Cryst. 2002, B58, 380-388).
Keywords CSD; crystal structure; phosphoric triamide
Received 15 September 2012; accepted 23 October 2012.
Address correspondence to Mahnaz Rostami Chaijan, Department of Chemistry, Ferdowsi University of
Mashhad, Mashhad, Iran. E-mail: rostami m17@yahoo.com
224

A NEW SOLVATED PHOSPHORIC TRIAMIDE, [(C6H4(3-CH3)NH)3P(O)] · (C2H5OH)
225
INTRODUCTION
The hybridization of the nitrogen atom bonded to the phosphorus atom in phos-
phoric triamides with an [N][N’][N”]P O skeleton tends toward sp2,1 similar to nitro-
gen atoms bonded to carbon atoms in organic amides.2 This tendency is reflected in
the bond-angle sums around such nitrogen atoms, which was recently investigated for
RC(O)NHP(O)[NR1R2]2 phosphoric triamides3 through a database analysis of the struc-
tures deposited in the Cambridge Structural Database.4 Here, we continue such analysis for
[R1R2N]P(O)[NR3R4][NR5R6] phosphoric triamides.
From the point of view of the bonding, the main difference between RC(O)NHP(O)
[NR1R2]2 and [R1R2N]P(O)[NR3R4][NR5R6] phosphoric triamides is related to the presence
of carbonyl group in the former class. Thus, the lone electron pair (LEP) of the NCP [the
nitrogen atom of O C NH P O fragment] is tending to delocalize over the C O group.
This leads to different strengths for P N bonds in RC(O)NHP(O)[NR1R2]2 phosphoric
triamides where the P NP [NP is the nitrogen atom of NR1R2] is shorter than P NCP
.
Moreover, apart from P NCP, it is well-known that the P N bonds in phosphoramides are
shorter than the P N single bond.3
It should be noted that in [R1R2N]P(O)[NR3R4][NR5R6] phosphoric triamides, three
NP atoms compete for electron-donation to the phosphorus atom as compared to two NP
atoms in RC(O)NHP(O)[NR1R2]2 phosphoric triamides.
Here, we present the synthesis, spectroscopic characterization and crystal structure
of a new solvated phosphoric triamide, [(C6H4(3-CH3)NH)3P(O)] · (C2H5OH), Scheme 1.
Moreover, the geometries of nitrogen atoms bonded to the phosphorus atom in this
structure and 59 analogous structures deposited in the CSD are compared to those of
RC(O)NHP(O)[NR1R2]2 phosphoric triamides.
Scheme 1

226
M. POURAYOUBI ET AL.
RESULTS AND DISCUSSION
Of the numerous known OP[N(H)R]3 phosphoric triamides, structures have
been determined only for R = H,5 phenyl,6 m-tolyl,7 p-tolyl,8 methyl, tert-butyl,9
2-pyridyl,10 benzyl,11 cyclohexyl,12 and p-methoxyphenyl.13 A search in the CSD for
compounds with a P(O)[N]3 skeleton, without considering complexes, shows that 191
structures have been deposited, so far, belonging to RC(O)NHP(O)[NR1R2]2 (93) and
[R1R2N]P(O)[NR3R4][NR5R6] (88) and some other families. In these structures, the
nitrogen atoms tend towards planarity, which is reflected in the bond angles around
the nitrogen atoms (2 × P N C + C N C or P N H + H N C + C N P).
These bond-angle sums usually show a few deviations from the planar value of 360◦;
however, values in the range of 339.07◦ to 360.72◦ for RC(O)NHP(O)[NR1R2]2 and
325.2◦ to 360.4◦ for [R1R2N]P(O)[NR3R4][NR5R6] were reported. The largest deviations
are related to three-membered cyclic amido moiety (phosphoric triamide compounds with
three membered cyclic amido moiety were not considered in this analysis). Moreover,
some co-crystals and phosphoric triamides with disorder in amido fragments were
excluded.
A CSD analysis on RC(O)NHP(O)[NR1R2]2 phosphoric triamides shows that the
P NP bond lengths are in the range of 1.60–1.70 Å; whereas, the P NCP appears in
the range 1.66–1.74 Å.3 This means that the electron deficiency of phosphorus atom
is more provided by two NR1R2 groups; whereas, the NCP is involved in resonance
interaction with C O. So, may be the lower availability of electron of NCP leads to
more efficient interaction of NP atoms with P atoms. If it is true, the NP atoms in
RC(O)NHP(O)[NR1R2]2 phosphoric triamides should display a more planar environ-
ment than the NP atoms in [R1R2N]P(O)[NR3R4][NR5R6] phosphoric triamides. This ten-
dency may appear in the average of the sum of the surrounding bond angles at the NP
atoms.
For this purpose, the cif files of all RC(O)NHP(O)[NR1R2]2 phosphoric triamides
were analyzed and the bond-angle sum (SUM = 2 × P N C + C N C or P N
H + H N C + C N P related to the amido moiety bonded to P) for each NP
atom was considered. Then, SUMav = 0.5 (SUM1 + SUM2) was calculated. For
[R1R2N]P(O)[NR3R4][NR5R6] phosphoric triamides, SUMav = 0.33 (SUM1 + SUM2
+ SUM3) was considered. These average values are shown in Figure 1, which shows
that the [R1R2N]P(O)[NR3R4][NR5R6] phosphoric triamides, in deposited structures, have
relatively lower values than RC(O)NHP(O)[NR1R2]2 phosphoric triamides; i.e., the three
amido moieties in [R1R2N]P(O)[NR3R4][NR5R6] phosphoric triamides compete with each
other and in overall, they have lower SUMav values or more pyramidal N atoms.
Of course, the bond-angle sum is also related to the type of amido substituent;
for example, sum of the three bond angles at the N atoms (of p-methoxy phenyl amido
substituent) in C18H18N3O1P1 (KEQLUO14) are about 360◦.
In this work, we investigate a new structure, N,N’,N”-tris(3-methyl-phenyl) phosph–
oric triamide, ethanol solvate (Scheme 1). The asymmetric unit is composed of three
independent phosphoric triamide molecules and three ethanol molecules. One of the in-
dependent molecule and the asymmetric unit are shown in Figures 2 and 3, respectively.
Data collection and structure refinement parameters are given in Table 1. Selected bond
distances and bond angles and the hydrogen-bonds geometry are provided in Tables 2 and
3. Figure 4 shows packing of the title solvated compound.

A NEW SOLVATED PHOSPHORIC TRIAMIDE, [(C6H4(3-CH3)NH)3P(O)] · (C2H5OH)
227
Figure 1 The SUMav values at the N atoms of [R1R2N]P(O)[NR3R4][NR5R6] phosphoric triamides (bottom
line, brown in the electronic version of paper) and RC(O)NHP(O)[NR1R2]2 phosphoric triamides (top line, blue)
(Color figure available online).
Figure 2 ORTEP diagram of one of the independent phosphoric triamide molecules; thermal ellipsoids are at
30% probability level (Color figure available online).

228
M. POURAYOUBI ET AL.
Table 1 Crystal data and structure refinement
Empirical formula
Formula weight
Temperature
C21H24N3OP,C2H6O
411.47
150(1)K
Wavelength
0.71073
Crystal system
Space group
Triclinic
P-1
Unit cell dimensions
a = 12.5401(11) Å, b = 12.8961(7)
Å, c = 23.8258(10) Å
α = 92.411(4)◦, β = 101.934(5)◦, γ
= 114.075(6)◦
Volume
3407.2(4)
Z
6
Density (calculated)
Absorption coefficient
F(000)
Crystal size
Theta range for data collection
Index ranges
1.203
0.144
1320
0.40×0.36×0.26 mm3
1.83 to 27.50
−16 ≤ h ≤ 16, −16 ≤ k ≤ 16, −30
≤ l ≤ 29
Reflections collected
66369
Independent reflections
15486 [Rint = 0.094]
The P O (1.488(4) Å, 1.489(3) Å and 1.487(4) Å) and P N (in the range of 1.633(4)
Å to 1.642(4) Å) bond lengths are within the expected values.14 The bond angles around P
atoms are in the range of 98.0(2)◦ to 116.5(2)◦. The P N C bond angles are in the range
of 126.3(3) to 130.8(4)◦ (Table 2).
Table 2 Selected geometric parameters
P2-O4
1.489(3)
1.640(4)
1.640(5)
1.640(4)
1.487(4)
1.638(5)
P3-N800
P3-N900
P1-N100
P1-N200
P1-O2
1.639(4)
1.634(6)
1.642(4)
1.633(5)
1.488(4)
1.641(4)
P2-N400
P2-N500
P2-N600
P3-O5
P3-N700
P1-N300
O4-P2-N400
O4-P2-N500
O4-P2-N600
N400-P2-N500
N400-P2-N600
N500-P2-N600
C201-N400-P2
C208-N500-P2
C215-N600-P2
O5-P3-N700
105.46(19)
115.5(2)
115.1(2)
110.5(2)
111.0(2)
99.3(2)
130.8(3)
127.3(3)
127.6(4)
116.5(2)
115.1(2)
116.5(2)
110.7(2)
111.1(3)
N800-P3-N900
C315-N900-P3
C301-N700-P3
C308-N800-P3
O2-P1-N300
98.0(2)
130.8(4)
129.5(3)
129.0(3)
114.4(2)
115.6(2)
105.4(2)
111.1(2)
99.6(2)
110.9(2)
126.3(3)
129.5(3)
127.2(4)
O2-P1-N100
O2-P1-N200
N100-P1-N200
N100-P1-N300
N200-P1-N300
C101-N100-P1
C108-N200-P1
C115-N300-P1
O5-P3-N900
O5-P3-N800
N700-P3-N800
N700-P3-N900

A NEW SOLVATED PHOSPHORIC TRIAMIDE, [(C6H4(3-CH3)NH)3P(O)] · (C2H5OH)
229
Figure 3 The asymmetric unit of [(C6H4(3-CH3)NH)3P(O)].(C2H5OH); the hydrogen atoms are omitted for
clarity and only the P atoms of phosphoric triamide molecules and the O atoms of C2H5OH molecules are labeled.
Thermal ellipsoids are at 30% probability level (Color figure available online).
In the crystal, adjacent molecules are linked via (O H)(N H)···O P and
(N H)2···O C groups in a linear arrangement (O···O in the range of 2.655(5)
Å to 2.704(5) Å and N···O in the range of 2.854(5) Å to 2.997(5) Å) (Table 3)
in which the oxygen atoms of phosphoryl groups and ethanol molecules act as a
Table 3 Hydrogen bonds
D
H···A
D
H
H···A
2.02
2.14
2.25
2.17
2.10
2.08
2.03
2.11
2.04
1.84
1.90
1.89
D···A
D
H···A
N400 H400···O2
N100 H100···O3
N700 H700···O5
N500 H500···O7
N200 H200···O4
N300 H300···O3
N600 H600···O7
N800 H800···O1
N900 H900···O1
O1 H1···O2
0.86
0.86
0.86
0.86
0.86
0.86
0.86
0.86
0.86
0.82
0.82
0.82
2.854(5)
2.963(5)
2.958(5)
2.997(5)
2.905(5)
2.912(6)
2.865(6)
2.946(5)
2.881(5)
2.655(5)
2.704(5)
2.690(5)
164
161
140
160
155
163
165
163
167
174
167
166
O3 H3···O5
O7 H7···O4
Symmetry codes: (i) x, −y+1/2, z−1/2; (ii) x, −y+1/2, z+1/2.

230
M. POURAYOUBI ET AL.
Figure 4 Partial packing view showing the formation of the chain through N H···O and O H···O hydrogen
bonds which are shown as dotted lines. H atoms not involved in hydrogen bonding have been omitted for the sake
of clarity. (Color figure available online).
double-H bond acceptor, for a definition of double-H bond acceptor, see: Reference
paper.15
Synthesis
To a solution of phosphoryl chloride (6.63 mmol, 1.017 g) in dry chloroform, 3-
methyl toluidine (39.78 mmol, 4.263 g) was added dropwise at 0◦C. After 4h, the solvent
was removed in vacuum and the solid was washed with H2O. Suitable single crystals for X-
ray crystallography were obtained at room temperature from a mixture of C2H5OH/CH3CN
(4:1 ratio).
1
31P{ H} NMR (202.45 MHz, DMSO-d6, 300.0 K, H3PO4 external): δ = −3.95, 1H
NMR (500.13 MHz, DMSO-d6, 300.0 K, TMS): δ = 1.14 (t, 3H, CH3), 2.16 (s, 3H, CH3),
3.56 (q, 2H, CH2), 6.70 (d, 2JP-H =7.0 Hz, 3H, NH), 6.86–7.05 (m, 4H, Ar-H), 13C NMR
(125.75 MHz, DMSO-d6, 300.0 K, TMS): δ = 18.76 (s, CH3), 18.76 (s, CH3), 57.96 (s,
CH2), 115.72 (d, JP-C = 6.6 Hz), 118.25 (s), 119.40 (d, JP-C = 7.2 Hz), 122.90 (s), 129.85
(s), 139.87 (s), IR (KBr, cm−1): 3378, 2964, 2789, 1714, 1495, 1378, 1203, 1174, 1033,
882, 790.
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A NEW SOLVATED PHOSPHORIC TRIAMIDE, [(C6H4(3-CH3)NH)3P(O)] · (C2H5OH)
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