4-methoxyphenylphosphonic acid: Reactivity of Lawesson's reagent

Article abstract of DOI:10.1107/S0108270102004547

Reactivity of Lawesson's reagent was investigated by synthesizing 4-methoxyphenylphosphonic acid, obtained as a by-product from the reaction of the reagent with methyl iodide. The structures of the compounds were rationalized in terms of their significant

Full text of DOI:10.1107/S0108270102004547

organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
dithiadiphosphetane) and methyl bromide in a sealed tube
gives methyl phenylphosphonobromidodithioate in almost
quantitative yield (Von Fluk & Binder, 1967). Compound (II)
can be considered the ®nal desulfurated product in the S/O
interchange reaction taking place at the P atom of (I) during
thionation reactions. In this case, the O atoms probably come
from traces of water in the solvent and/or from air during
crystallization. A compound similar to (II) [structure (III) in
the Scheme] was obtained from the reaction of 2,4-(naph-
thalene-1,8-diyl)-2,4-dithio-1,3,2,4-dithiadiphosphetane with
ethylene glycol at 413 K (Kilian et al., 1999). As in the struc-
ture of (II), the two P atoms are coordinated to four O atoms
which come from ethylene glycol, but a PÐOÐP bridge is
built into a six-membered C3P2O heterocycle due to the
rigidity of the organyl backbone.
ISSN 0108-2701
4-Methoxyphenylphosphonic acid:
reactivity of Lawesson's reagent
M. Carla Aragoni,a Massimiliano Arca,a Alexander J.
Blake,b* Vito Lippolis,a Martin Schroderb and Claire
È
Wilsonb
aDipartimento di Chimica Inorganica ed Analitica, Complesso Universitario di
Monserrato, SS 554 Bivio per Sestu, 09042 Monserrato (CA), Italy, and bSchool of
Chemistry, The University of Nottingham, University Park, Nottingham NG7 2RD,
England
Correspondence e-mail: a.j.blake@nottingham.ac.uk
Received 26 February 2002
Accepted 11 March 2002
Online 11 April 2002
The title compound, C7H9O4P, obtained as a by-product of the
reaction between Lawesson's reagent, (I), and CH3I, can be
recognized as the ®nal product of the S/O interchange reaction
at the P atom of (I). Hydrogen bonds of type PÐOÐ
HÁ Á ÁO P link molecules into helical chains and form ten-
membered hydrogen-bonded rings with the graph-set notation
R23(10). Weaker intermolecular contacts between PÐO and a
phenyl H atom link the chains into a three-dimensional lattice.
The parent benzenephosphonic acid [Weakley (1976). Acta
Cryst. B32, 2889±2890] does not adopt an analogous structure,
but its arsenic analogue [Shimada (1960). Bull. Chem. Soc.
Jpn, 33, 301±304] does and can be regarded as isostructural.
We rationalize these three structures in terms of their
signi®cant intermolecular interactions.
The intramolecular geometry of (II) is unexceptional and
we note only the distinction between the two equivalent PÐO
Ê
single bonds of 1.552 (2) and 1.557 (2) A and the P
O
Ê
distance of 1.511 (2) A (Fig. 1 and Table 1), and the typical
coplanarity of the anisole methoxy substituent at C4 with its
phenyl ring [e.g. C3ÐC4ÐO4ÐC4M 8.8 (5)ꢀ]. However,
there are two unique, but geometrically similar, hydrogen
bonds of type PÐOÐHÁ Á ÁO P (Fig. 2 and Table 2), which
result in the formation of ten-membered hydrogen-bonded
Comment
It is widely recognized that 2,4-bis(4-methoxyphenyl)-2,4-di-
thio-1,3,2,4-dithiadiphosphetane [Lawesson's reagent, (I);
Yde et al., 1984; Scheibye et al., 1978a,b, 1982; Shabana et al.,
1980; Pedersen et al., 1978] is among the most effective thio-
nating agents for organic molecules and plays a crucial role in
the synthesis of phosphorus-containing rings (Cherkasov et al.,
1985; Foreman & Woollins, 2000). The wide range of appli-
cations, along with the variety of transformations and new
products that can be made using it, make it one of the most
widely used and versatile reagents. Recently, while exploring
the high reactivity of (I) towards nucleophilic reagents, which
is one of its most characteristic features, we obtained new
phosphonodithioates and amidophosphonodithioates, and
their metal complexes (Arca et al., 1997; Aragoni et al., 2000).
In an attempt to explore further the reactivity of Lawes-
son's reagent, 4-methoxyphenylphosphonic acid, (II), has
been obtained as a by-product from the reaction of (I) with
methyl iodide. Interestingly, a similar reaction between a
structural analogue of (I) (i.e. 2,4-diphenyl-2,4-dithio-1,3,2,4-
rings, each containing three PÐOH donors and two P
O
acceptors, giving a graph-set notation R23(10) (Bernstein et al.,
1995). Successive molecules are related by the operation of a
21 screw axis parallel to a. The overall helical structure along a
is generated by repetition of these rings in that direction. In
addition, there is a weak interaction between an H atom on
the phenyl ring and the PÐO related by the screw axis parallel
to b, which links the chains into a three-dimensional lattice
Figure 1
A view of the title molecule showing the atom-numbering scheme.
Displacement ellipsoids are drawn at the 50% probability level.
o260 # 2002 International Union of Crystallography
DOI: 10.1107/S0108270102004547
Acta Cryst. (2002). C58, o260±o262

organic compounds
3
2
12 + y,
z): HÁ Á ÁO 2.56 A, CÁ Á ÁO
tions along b, but is rather tolerant of extension in the c
direction as there are no important interactions along that
axis. It would be interesting to explore the limits of this
tolerance by increasing the length of the substituent on C4.
Ê
[C3ÐH3Á Á ÁO2( x,
ꢀ
Ê
3.465 (4) A and CÐHÁ Á ÁO 159 ].
There are very few structures of arylphosphonic acids in the
literature; in fact, we have identi®ed only three, two of which
(Nieger et al., 1999a,b) are dimethyl sulfoxide solvates, where
the solvent molecules are involved in the hydrogen bonding,
and which are, therefore, not comparable with the title
compound. The only immediate comparison is with the parent
benzenephosphonic acid, PhP(O)(OH)2 (Weakley, 1976), in
which hydrogen bonding produces puckered layers of mol-
ecules with only weak contacts between these layers. Each PÐ
OH group participates in one hydrogen bond, but the O atom
of the P O group accepts two hydrogen bonds. In contrast to
the title compound, the layers in PhP(O)(OH)2 contain
centrosymmetric pairs of molecules. The chains observed in
the title compound are, therefore, more analogous to the
structure of PhAs(O)(OH)2 (Shimada, 1960) than to that of
PhP(O)(OH)2 (Weakley, 1976). Allowing for an extension of
the c axis caused by the addition of the 4-methoxy substituent,
the unit-cell dimensions are comparable [a = 4.70, b = 10.42
Experimental
Lawesson's reagent, (I) (0.50 g, 1.2 mmol), was dissolved in toluene
(60 ml, dried over molecular sieves) under a dinitrogen atmosphere,
and then a fourfold stoichiometric excess of CH3I was added. The
reaction mixture was re¯uxed for 5 h and the resulting solid was then
®ltered off. Compound (II) separated from the ®ltrate as white
needles after two weeks standing in the open atmosphere. Elemental
analysis (%), found (calculated for C7H9O4P): C 44.53 (44.69), H 4.71
(4.82).
Crystal data
C7H9O4P
Mr = 188.11
Orthorhombic, P212121
Mo Kꢀ radiation
Cell parameters from 1415
re¯ections
ꢁ = 2.3±26.4ꢀ
Ê
a = 4.5819 (6) A
1
Ê
b = 10.0867 (13) A
ꢂ = 0.30 mm
T = 150 (2) K
Ê
Ê
c = 18.087 (2) A
Ê
V = 835.91 (18) A
and c = 14.92 A for PhAs(O)(OH)2] and the compounds adopt
3
Lath, colourless
0.31 Â 0.07 Â 0.04 mm
the same space group, P212121, and the same packing motif via
hydrogen bonding. They can, therefore, be regarded as
isostructural.
Z = 4
Dx = 1.495 Mg m
3
We have attempted to rationalize the relationship of the
structures of (II), PhAs(O)(OH)2 and PhP(O)(OH)2. In the
last of these, any extension to the length of the molecule,
whether by substitution at the 4-position of the phenyl ring or
by exchanging As for P, would push the layers further apart,
thereby destabilizing the structure. In contrast, the motif
assumed by (II) and PhAs(O)(OH)2 depends on strong
hydrogen bonding along the a direction and weaker interac-
Data collection
Bruker SMART1000 CCD area-
detector diffractometer
! scans
5423 measured re¯ections
1210 independent re¯ections
939 re¯ections with I > 2ꢃ(I)
Rint = 0.090
ꢁmax = 28.8ꢀ
h = 5 ! 6
k = 11 ! 13
l = 24 ! 22
Re®nement
Re®nement on F2
R[F2 > 2ꢃ(F2)] = 0.042
wR(F2) = 0.094
S = 0.94
1210 re¯ections
112 parameters
H-atom parameters constrained
w = 1/[ꢃ2(Fo2) + (0.050P)2]
where P = (Fo2 + 2Fc2)/3
(Á/ꢃ)max = 0.001
3
Ê
Áꢄmax = 0.30 e A
3
Ê
0.31 e A
Áꢄmin
=
Table 1
Selected geometric parameters (A, ).
ꢀ
Ê
PÐO1
PÐO2
1.511 (2)
1.557 (2)
PÐO3
PÐC1
1.552 (2)
1.771 (3)
O1ÐPÐO2
O1ÐPÐO3
O2ÐPÐO3
112.03 (13)
109.88 (13)
110.12 (12)
O1ÐPÐC1
O2ÐPÐC1
O3ÐPÐC1
110.97 (14)
105.96 (14)
107.73 (15)
C3ÐC4ÐO4ÐC4M
8.8 (5)
C5ÐC4ÐO4ÐC4M
171.2 (3)
Table 2
Hydrogen-bonding geometry (A, ).
ꢀ
Ê
DÐHÁ Á ÁA
DÐH
HÁ Á ÁA
DÁ Á ÁA
DÐHÁ Á ÁA
Figure 2
A view of part of a helix of molecules in the title structure linked by
O2ÐH2OÁ Á ÁO1i
0.84
0.84
1.75
1.72
2.580 (3)
2.550 (3)
169
169
O3ÐH3OÁ Á ÁO1ii
hydrogen bonding. The helices run parallel to the crystallographic a axis.
y, 2 z; (ii) x 1, y, z; (iii) x + 12, 23 y,
1
2
3
2
[Symmetry codes: (i) x
z; (iv) x + 1, y, z.]
,
1
2
3
2
Symmetry codes: (i) x
;
y; 2 z; (ii) x 1; y; z.
2
ꢁ
Acta Cryst. (2002). C58, o260±o262
M. Carla Aragoni et al. C7H9O4P o261

organic compounds
Bernstein, J., Davis, R. E., Shimoni, L. & Chang, N.-L. (1995). Angew. Chem.
Int. Ed. Engl. 34, 1555±1573.
Bruker (1997). SHELXTL. Version 5.1. Bruker AXS Inc., Madison,
Wisconsin, USA.
Bruker (1998). SMART (Version 5.054) and SAINT (Version 6.01). Bruker
AXS Inc., Madison, Wisconsin, USA.
Cherkasov, R. A., Kutyrev, G. A. & Pudovik, N. (1985). Tetrahedron, 41, 2567±
2624.
A meaningful Flack (1983) parameter could not be determined; it
re®ned to a value of 0.4 (2) and so Friedel opposites were merged for
the ®nal stages of the re®nement. Hydroxyl and methyl H atoms were
located from ÁF syntheses and thereafter re®ned as part of rigid
rotating groups, with Uiso(H) = 1.5Ueq(O,C); aromatic H atoms were
placed geometrically and then allowed to re®ne riding on their parent
atoms, with Uiso(H) = 1.2Ueq(C). The following distance constraints
were applied: OÐH = 0.84, methyl CÐH = 0.98 and aromatic CÐH =
Flack, H. D. (1983). Acta Cryst. A39, 876±881.
Foreman, M. St J. & Woollins, J. D. (2000). J. Chem. Soc. Dalton Trans. pp.
1533±1543.
Ê
0.95 A.
Kilian, P., Slawin, A. M. Z. & Woollins, J. D. (1999). Eur. J. Inorg. Chem. pp.
2327±2333.
Nieger, M., Niecke, E. & Serwas, R. (1999a). Refcode HORWOU. Private
communication to the Cambridge Structural Database, 12 Union Road,
Cambridge, England.
Nieger, M., Niecke, E. & Serwas, R. (1999b). Refcode HORWUA. Private
communication to the Cambridge Structural Database, 12 Union Road,
Cambridge, England.
Data collection: SMART (Bruker, 1998); cell re®nement: SAINT
(Bruker, 1998); data reduction: SAINT and SHELXTL (Bruker,
1997); program(s) used to solve structure: SHELXS97 (Sheldrick,
1990); program(s) used to re®ne structure: SHELXL97 (Sheldrick,
1997); molecular graphics: SHELXTL; software used to prepare
material for publication: SHELXL97 and PLATON (Spek, 2001).
Pedersen, B. S., Scheibye, S., Nilsson, N. H. & Lawesson, S.-O. (1978). Bull.
Soc. Chim. Belg. 87, 223±228.
Scheibye, S., Pedersen, B. S. & Lawesson, S.-O. (1978a). Bull. Soc. Chim. Belg.
87, 229±238.
We thank EPSRC for the provision of a diffractometer and
are grateful to Dr Peter Hubberstey for helpful discussions.
Scheibye, S., Pedersen, B. S. & Lawesson, S.-O. (1978b). Bull. Soc. Chim. Belg.
87, 299±306.
Scheibye, S., Shabana, R. & Lawesson, S.-O. (1982). Tetrahedron, 38, 993±
1001.
Supplementary data for this paper are available from the IUCr electronic
archives (Reference: NA1560). Services for accessing these data are
described at the back of the journal.
Shabana, R., Scheibye, S., Clausen, K., Olesen, S. O. & Lawesson, S.-O. (1980).
Nouv. J. Chim. 4, 47±51.
Sheldrick, G. M. (1990). Acta Cryst. A46, 467±473.
È
Sheldrick, G. M. (1997). SHELXL97. University of Gottingen, Germany.
References
Shimada, A. (1960). Bull. Chem. Soc. Jpn, 33, 301±304.
Spek, A. L. (2001). PLATON. University of Utrecht, The Netherlands.
Von Fluk, E. & Binder, H. (1967). Z. Anorg. Chem. 354, 113±224.
Weakley, T. J. R. (1976). Acta Cryst. B32, 2889±2890.
Aragoni, M. C., Arca, M., Demartin, F., Devillanova, F. A., Graiff, C., Isaia, F.,
Lippolis, V., Tiripicchio, A. & Verani, G. (2000). Eur. J. Inorg. Chem. pp.
2239±2244.
Arca, M., Cornia, A., Devillanova, F. A., Fabretti, A. C., Isaia, F., Lippolis, V. &
Verani, G. (1997). Inorg. Chim. Acta, 262, 81±84.
Yde, B., Yuosif, N. M., Pedersen, U., Thomsen, I. & Lawesson, S.-O. (1984).
Tetrahedron, 40, 2047±2052.
ꢁ
o262 M. Carla Aragoni et al.
C7H9O4P
Acta Cryst. (2002). C58, o260±o262