Formation of a novel phenyldiphosphonic acid anion dimer through metal assisted hydrolysis of the P-N bond

Article abstract of DOI:10.1021/ic010624l

Reaction of PhP(O)(3,5-Me₂Pz)₂ or Ph₂P(O)(3,5-Me₂Pz) with PdCl₂(C₆H₅CN)₂ leads to a facile and complete P-N bond hydrolysis; in the former reaction a novel diphosphonic acid anion dimer has been isolated.

Full text of DOI:10.1021/ic010624l

Inorg. Chem. 2001, 40, 6057-6060
6057
pyrazolyl ligands appears to be the hydrolytic sensitivity of the
P-N bond particularly after interaction of the ligand with
transition metal ions. Thus, tris(3,5-dimethyl pyrazolyl) phos-
phine oxide, (3,5-Me2Pz)3PdO, undergoes a P-N bond hy-
drolysis and is converted in situ into [(3,5-Me2Pz)2PO2]- upon
interaction with Cu(II) salts6c or a metal carbonyl.6d Recently
we have observed an unusual desulfurization-cum-hydrolysis
of MeP(S)(3,5-Me2Pz)2 upon interaction with CuCl2.7a To probe
if these reactions are general, we have prepared two different
pyrazolyl ligands PhP(O)(3,5-Me2Pz)2, 1, and Ph2P(O)(3,5-Me2-
Pz)2, 2, and studied their interaction with Pd(II) salts. In both
of these cases we find that the interaction with the metal ion
accelerates the P-N bond hydrolysis. These results are presented
in this paper. We also report the X-ray crystal structure of [Pd-
(3,5-Me2Pz)3Cl]+[PhP(O)(OH)OP(O2)Ph]-, 3, which contains
an anion formed from the condensation of the phenylphosphonic
acid PhP(O)(OH)2 formed in situ in the interaction of 1 and
PdCl2. This anion represents the first example of an anionic
diphosphonic acid anhydride containing a P-C bond.
Formation of a Novel Phenyldiphosphonic Acid
Anion Dimer through Metal Assisted Hydrolysis
of the P-N Bond
Savariraj Kingsley,† Ashwani Vij,‡ and
Vadapalli Chandrasekhar*,†
Department of Chemistry, Indian Institute of Technology,
Kanpur-208 016, India, and Department of Chemistry,
University of Idaho, Moscow, Idaho 83844-3010
ReceiVed June 12, 2001
Introduction
Polypyrazolyl borates [HB(Pz)3]- and [H2B(Pz)2]- (Pz )
pyrazolyl or substituted pyrazolyl) are among the most widely
studied multidentate ligand systems.1 This is due to three
factors: (a) they are readily synthesized in very good yields by
a one-step synthesis, (b) they have excellent binding properties
toward a large range of transition and lanthanide metal ions,2
and (c) these ligands can be easily modulated by varying the
stereo-electronic properties of the substituents on the pyrazolyl
group.3 Because of these favorable properties pyrazolyl borates
have found application as ligands in various research themes
including organometallic4 and bioinorganic chemistry.5 In
principle, the versatility of these polypyrazolyl borates can be
matched by the corresponding phosphorus analogues P(Pz)3,
(E)P(Pz)3, RP(E)(Pz)2, or R2P(E)(Pz) [E ) O, or S; R ) alkyl
or aryl]. However, in practice, the number of such examples is
limited.6a,b One of the chief defects of the phosphorus based
Experimental Section
The solvents were purified and dried according to standard proce-
dures.8 Diphenylphosphinic chloride, P,P-dichlorophenylphosphine
oxide, and PdCl2‚2C6H5CN were acquired from Fluka, Switzerland,
and used as such. Triethylamine (Qualigens, India) was dried over KOH
and freshly distilled before use. The compound 3,5-dimethylpyrazole
was prepared according to the literature procedure.8
Instrumentation. Infrared spectra were recorded as KBr pellets using
a Bruker Vectra 22 FTIR spectrophotometer. 1H and 31P NMR spectra
were recorded on a JEOL spectrometer operating at 400 and 60 MHz
respectively. Mass spectra were recorded on a JEOL SX 102/ DA 6000
mass spectrometer using Xenon (6Kv, 10 mA) as the FAB gas. C, H,
and N analyses were carried out at the Central Drug Research Institute’s
(Lucknow, India) regional instrumentation facility. All the preparative
procedures described in the following were carried out under an inert
gas atmosphere of dry N2.
† Department of Chemistry, Indian Institute of Technology.
‡ Department of Chemistry, University of Idaho.
(1) (a) Trofimenko, S. Chem. ReV. 1993, 93, 943. (b) Parkin, G. AdV.
Inorg. Chem. 1996, 42, 291. (c) Hu, Z.; Gorun, S. Inorg. Chem. 2001,
40, 667. (d) LeCloux, D. D.; Keyes, M. C.; Osawa, M.; Reynolds,
V.; Tolman, W. B. Inorg. Chem. 1994, 33, 3, 6361. (e) LeCloux, D.
D.; Tokar, C. J.; Osawa, M.; Houser, R. P.; Keyes, M. C.; Tolman,
W. B. Organometallics 1994, 13, 2855.
(2) (a) Long, D. P.; Chandrasekaran, A.; Day, R. O.; Bianconi, P. A.;
Rheingold, A. L. Inorg. Chem. 2000, 39, 4476. (b) Fleming, J. S.;
Psillakis, E.; Couchman, M. S.; Jeffery, J. C.; McCleverty, J. A.; Ward,
M. D.; J. Chem. Soc., Dalton Trans. 1998, 537. (c) Jones, P. L.;
Amoroso, A. J.; Jeffery, J. C.; McCleverty, J. A.; Psillakis, E.; Rees,
L. H.; Ward, M. D. Inorg. Chem. 1997, 36, 10. (d) Bardwell, D. A.;
Jeffery, J. C.; Jones, P. L.; McCleverty, J. A.; Psillakis, E.; Reeves,
Z.; Ward, M. D. J. Chem. Soc., Dalton Trans. 1997, 2079.
(3) (a) Rasika Dias, H. V.; Wang, Z.; Jin, W. Inorg. Chem. 1997, 36,
6205. (b) Rheingold, A. L.; Haggerty, B. S.; Yap, G. P. A.;
Trofimenko, S. Inorg. Chem. 1997, 36, 5097. (c) Rheingold, R. L.;
Yap, G. P. A.; Liable-Sands, L. M.; Guzei, I. A.; Trofimenko, S. Inorg.
Chem. 1997, 36, 6261. (d) Fillebeen, T.; Parkin, G. Inorg. Chem. 1997,
36, 3787. (e) Kuchta, M. C.; Bonanno, J. B.; Parkin, G. J. Am. Chem.
Soc. 1996, 118, 10914.
Synthesis of PhP(O)(3,5-Me2Pz)2, 1. P,P′-Dichlorophenylphosphine
oxide (4.87 g, 24.9 mmol) was added dropwise through a syringe to a
solution of 3,5-dimethylpyrazole (4.81 g, 50.0 mmol) and triethylamine
(5.06 g, 50.0 mmol) in benzene at 10 °C. The reaction mixture was
heated under reflux for 10 h. This was allowed to come to room
temperature, filtered, and the filtrate stripped of the solvent in vacuo
to afford a semisolid, which was dissolved in a mixture of CH2Cl2/n-
hexane (1:1) and kept at 5 °C to afford 1 (yield: 7.00 g, 89%). Mp:
57 °C. IR (KBr): 3200(m), 1600(s), 1420(s), 1200(vs), 1150(w),
1
1090(m), 900(m), 810(w), 700(s) cm-1. H NMR (CDCl3): δ ) 2.1
(s, 6H, CH3-), 2.3 (s, 6H, CH3-), 5.9 (s, 2H, 4-H pyrazole), 7.8 (m,
5H, phenyl). 31P NMR (CDCl3): 13.7 (s). Mass(FAB): 315 [M+]. Anal.
Calcd for C16H19N4OP (Mr ) 314.32): C, 61.13; H, 6.09; N, 17.82.
Found: C, 61.01; H, 6.23; N, 17.91.
Synthesis of Ph2P(O)(3,5-Me2Pz), 2. Diphenylphosphinic chloride
(11.84 g, 50.0 mmol) dissolved in (20 mL) of dry benzene was added
dropwise to a solution of 3,5-dimethyl pyrazole (4.81 g, 50.0 mmol)
and triethylamine (5.06 g, 50.0 mmol) in benzene (100 mL) at 5 °C.
The resulting mixture was heated under reflux for 10 h, cooled to room
temperature, filtered, and the solvent removed from the filtrate under
reduced pressure to afford a white crystalline solid. Recrystallization
of this solid from hot CCl4 gave colorless blocks of pure 2 (yield: 13.0
(4) (a) Soper, J. D.; Bennett, B. K.; Lovell, S.; Mayer, J. M. Inorg. Chem.
2001, 40, 1888. (b) Akia, M.; Ohta, K.; Takahashi, Y.; Hikichi, S.;
Moro-oka, Y. Organometallics 1997, 16, 4121.
(5) (a) Komatsuzaki, H.; Nagasu, Y.; Suzuki, K.; Shibasaki, T.; Satoh,
M.; Ebina, F.; Hikichi, S.; Akita, M.; Moro-oka, Y. J. Chem. Soc.,
Dalton Trans. 1998, 511. (b) Kitajima, N.; Moro-oka, Y. Chem. ReV.
1994, 94, 737.
(6) (a) Tokar, C. J.; Kettler, P. B.; Tolman, W. B. Organometallics. 1992,
8, 2737. (b) Chowdhury, S. K.; Joshi, V. S.; Samuel, A. G.; Puranik,
V. G.; Tavale, S. S.; Sarkar, A. Organometallics 1994, 13, 4092. (c)
Chandrasekhar, V,; Nagendran, S.; Kingsley, S.; Krishnan, V.;
Boomishankar, R. Proc. Ind. Acad. Sci. (Chem. Sci.). 2000, 112, 171
(d) Joshi, V. S.; Kale, V. K.; Sathe, K. M.; Sarkar, A.; Tavale, S. S.;
Suresh, C. G. Organometallics. 1991, 10, 2898.
(7) (a) Chandrasekhar, V.; Kingsley, S.; Vij, A.; Lam, K. C.; Rheingold,
A. L. Inorg. Chem. 2000, 39, 3238. (b) Psillakis, E.; Jeffery, J. C.;
McCleverty, J. A.; Ward, M. D. J. Chem. Soc., Dalton Trans. 1997,
1645.
(8) Vogel’s Textbook of Practical Organic Chemistry, 5th ed.; Longman:
London, 1989.
10.1021/ic010624l CCC: $20.00 © 2001 American Chemical Society
Published on Web 09/28/2001

6058 Inorganic Chemistry, Vol. 40, No. 23, 2001
Notes
g, 87%). Mp: 76 °C. IR (KBr) 3060(m), 2920(w), 2500(m), 1800(w),
Scheme 1
1600(m), 1550(s), 1430(s), 1300(s), 1220(s), 1120(s), 1020(m), 800(m),
1
750(s) cm-1. H NMR (CDCl3): δ ) 2.2 (s, 3H, CH3-), 2.5 (s, 3H,
CH3-), 5.9 (s, 1H, 4-H pyrazole), 7.4-7.8 (m, 10H, phenyl). 31P NMR-
(CDCl3): δ ) 29.4(s). Mass: 297[M+]. Anal. Calcd for C17H17N2OP
(Mr ) 296.30): C, 68.90; H, 5.78; N, 9.45. Found: C, 68.81; H, 5.62;
N, 9.40.
Reaction of PhP(O)(3,5-Me2Pz)2 1 with PdCl2(C6H5CN)2. Ligand
1 (0.94 g, 2.9 mmol) was dissolved in 60 mL of dry dichloromethane
and to it was added PdCl2(C6H5CN)2 (1.15 g, 2.9 mmol). The resulting
mixture was stirred at 25 °C for 8 h. The solution was filtered, and the
clear solution was evaporated to dryness under reduced pressure to yield
a yellow powder. This was recrystallized from CH2Cl2/n-hexane (1:1)
to afford a yellow crystalline material identified as [Pd(3,5-Me2Pz)3Cl]+-
[PhP(O)(OH)OP(O)2Ph]-1, 3 (yield: 1.03 g). Mp: 198 °C. IR (KBr)
3260(m), 2300(w), 1570(s), 1380(s), 1290(s), 1170(m), 1000(m),
1
980(m), 810(s), 750(w), 730(w), 720(m) cm-1. H NMR (CDCl3): δ
) 2.7 (b, 18H, CH3-), 5.8 (s, 3H, 4-H pyrazole), 8.2 (m, 10H, phenyl)
9.3 (b, 3H, N-H). 31P NMR(CDCl3): 6.9(s).
Reaction of Ph2P(O)(3,5-Me2Pz), 2, with PdCl2(C6H5CN)2. The
reaction of 2 (0.89 g, 3 mmol) with PdCl2(C6H5CN)2 (1.15 g, 2.9 mmol)
was carried out in a 1:1 stoichiometry under similar conditions as
described above. Removal of solvent afforded a residue. This was
redissolved in CH2Cl2/n-hexane(1:1) and kept for crystallization. The
product obtained was identified as PdCl2‚(3,5-Me2Pz)2 4 by X-ray
crystallography.
X-ray Diffraction Study of 2. Single crystals suitable for diffraction
studies were grown by a slow evaporation of a solution of the compound
in a mixture of CH2Cl2/ n-hexane. Yellow transparent blocks of 2 were
obtained after a week’s time. A single crystal of approximate dimension
0.30 mm × 0.20 mm × 0.15 mm was mounted for diffraction studies.
The X-ray diffraction data were collected on a Siemens SMART3-
circle diffractometer equipped with a CCD detector. The structure was
solved by direct methods using the SHELX-90 program. The range of
the angle 2 for data collection was from 1.78 to 28.34. A total of 19299
the Cl and the N-H protons of the coordinated pyrazole group
(supplementary information). These hydrolysis reactions are
reminiscent of the situations found by others and us previously.7
As postulated by us previously it appears that in these ligands
containing a direct P-N bond, upon metalation the electrophi-
licity of the phosphorus center in the ligands 1 and 2 is
accentuated. This leads to the phosphorus center being readily
susceptible to attack by nucleophilic reagents such as water.
To prove this we have done an NMR experiment where the
chemical shifts of the ligands did not change even in the
presence of 3-4 equiv of water. However, upon the addition
of palladium chloride to the ligands in the NMR tube, there
was an immediate signal due to the formation of the hydrolyzed
phosphinic acid Ph2P(O)(OH) or the phosphonic acid PhP(O)-
(OH)2 or the diphosphonic acid anion [PhP(O)(OH)OP(O2)Ph]-
(Figure 1). Further evidence comes from the fact that the ligands
where the pyrazolyl group is separated from the phosphorus by
means of a spacer such as Ph2P(O)(OCH2CH2-3,5-Me2Pz) are
quite stable even upon interaction with transition metal ions.10
X-ray Structure of [Pd(3,5-Me2Pz)3Cl]+ [PhP(O)(OH)OP-
(O2)Ph]-, 3. Compound 3 crystallized in a monoclinic space
group P21/n with four molecules in the unit cell. Within an
asymmetric unit there are two components, a monochloro
palladium trispyrazole cation and a phenyldiphosphonic acid
anion as shown in Figure 2. The metric parameters for this
compound are also summarized in Figure 2; its structural
refinement data are given in Table 1. The geometry around
Pd(II) is square planar. Three free pyrazolyl ligands obtained
from the in situ hydrolysis of the ligand coordinate to the metal
ion. The fourth coordinating atom is a chloride ion. The Pd-
Cl bond length is 2.2846(14) Å and the Pd-N(pyrazole) distance
range from 1.999 to 2.023 Å. As shown in Figure 2 the hydrogen
atoms attached to the nitrogens of the pyrazole ligands are
involved in hydrogen bonding with the oxygen atoms of the
diphosphonic acid moiety. The centroids of the cationic Pd
moiety and anionic phenyl diphosphonic acid moiety are
separated by 5.45 Å.
reflections were collected of which 7731 were unique with Rint
)
0.0674. The structure was solved by heavy atom method, completed
by subsequent difference Fourier synthesis and refined on F2 by full
matrix least-squares procedures using SHELXTL9 version 5.03.5.
SADABS absorption correction was employed. The final goodness of
fit was 1.030 and the largest differential peak and hole was 0.324 and
-0.395 e-3. All hydrogens were fixed in their ideal positions using
suitable riding models except for the N-H and O-H hydrogens, which
were picked up from the Fourier map.
Results and Discussion
Synthetic Aspects. The ligands PhP(O)(3,5-Me2Pz)2, 1, and
Ph2P(O)(3,5-Me2Pz), 2, were prepared in nearly quantitative
yields by the reaction of the corresponding phosphinic halides
with 3,5-dimethylpyrazole in the presence of triethylamine as
the hydrogen chloride scavenger (Scheme 1). Both 1 and 2 show
sharp singlets in their 31P{1H}NMR at 13.7 and 29.4 ppm,
respectively. These compounds also show prominent parent ion
peaks in their FAB mass spectra. Another characteristic feature
of these ligands is the strong PdO absorption at 1200 and 1120
cm-1, respectively.
The interaction of the ligands 1 and 2 with PdCl2(C6H5CN)2
proceeds spontaneously and leads to P-N hydrolyzed products
[Pd(3,5-Me2Pz)3Cl]+[PhP(O)(OH)OP(O2)Ph]-, 3, and PdCl2(3,5-
Me2Pz)2, 4. Adventitious amounts of moisture seem to suffice
for this hydrolysis. It was not possible to obtain any other
products even when rigorous precautions were taken to exclude
moisture from the reaction system. The products 3 and 4 were
characterized crystallographically. The PdCl2(3,5-Me2Pz)2 forms
a dimer as a result of intermolecular hydrogen bonding between
The most interesting feature of compound 3 is the diphos-
phonic acid anion. Although there are many examples of this
structural motif involving condensed inorganic phosphates, the
anion in 3 represents the first example of its type involving an
organophosphorus compound. There is only one other example
related to the anion in 3, viz., 1,8-naphthahlene diphosphonic
(9) Sheldrick, G. M. SHELXTL, An Integrated System for SolVing, Refining
and Displaying Crystal Structures from Diffraction Data; University
of Gottingen: Gottingen, Germany, 1991.
(10) Kingsley, S.; Chandrasekhar, V.; Incarvito, C. D.; Lam, M. K.;
Rheingold, A. L. Inorg. Chem. (In press).

Notes
Inorganic Chemistry, Vol. 40, No. 23, 2001 6059
Figure 2. ORTEP plot of 3 (asymmetric unit) with thermal ellipsoids
at 50% probability. All hydrogen atoms except those involved in
hydrogen bonding are omitted for clarity. Important bond lengths
(angstroms) and bond angles (degrees) are Pd(1)-Cl(1) 2.2846(14),
Pd(1)-N(1) 2.023(4), Pd(1)-N(3) 1.999(4), Pd(1)-N(5) 2.021(4),
N(2)-H(2) 0.870(4), N(4)-H(4) 0.87(6), N(6)-H(6) 0.82(5), O(1)‚‚
‚H(4) 1.81(6), O(5)‚‚‚H(2) 1.932(3), O(5)‚‚‚H(6) 1.92(5), N(6)-H(6)-
O(5) 168(5), N(2)-H(2)-O(5) 165.4(3), N(4)-H(4)-O(1) 172(5),
N(1)-Pd(1)-Cl(1) 178.26(12), N(3)-Pd(1)-Cl(1) 89.53(12), N(3)-
Pd(1)-N(1) 89.9(2), N(3)-Pd(1)-N(5) 176.0(2), N(5)-Pd(1)-Cl(1)
88.57(11), and N(5)-Pd(1)-N(1) 92.1(2).
Table 1. Details of Data Collection and Structure Refinement for 3
empirical formula
fw
C27H35Cl1N6O5P2Pd1
727.42
crystal syst/space group
a, Å
b, Å
c, Å
monoclinic/P21/n
12.5566(5)
15.8960(6)
16.8390(6)
101.351(1)
3295.3(2)
4
â, deg
V, Å3
Z
temp, K
λ(Mo KR), Å
213(2)
0.710 73
1.466
0.785
0.0534
D
calcd, g cm-3
Figure 1. (A) 31P{1H} NMR spectrum of PhP(O)(3,5-Me2Pz)2. (B)
31P{1H} NMR spectrum of PhP(O)(3,5-Me2Pz)2 recorded immediately
after the addition of PdCl2(C6H5CN)2. Note the disappearance of ligand
peak. Peak at 7.01 corresponds to[PhP(O)(OH)OP(O2)Ph]- [Pd(3,5-
Me2Pz)3Cl]+ while peak at 17.98 corresponds to PhP(O)(OH)2. (C) 31P-
{1H} NMR spectrum of Ph2P(O)(3,5-Me2Pz). (D) 31P{1H} NMR
spectrum of Ph2P(O)(3,5-Me2Pz) recorded immediately after the
addition of PdCl2(C6H5CN)2. The new peak at 32.64 corresponds to
Ph2P(O)OH.
µ, mm-1
R1a
wR2b
0.1292
a R ) R1 ) ∑||Fo| - |Fc||/∑|Fo|. b Rw ) {[∑w(|Fo| - |Fc| )2]/
2
2
2
[∑w(|Fo| )2]}1/2
.
represent the longest P-O distances found in this molecule.
Interestingly the P2-O4(P-OH) is 1.488 Å and is considerably
shorter than either the bridging P-O distance or the P-O-
distance. The bridging P-O-P angle is 130.9°. The P-O-P
angles in pyrophosphates range from 130° to 180°.12 The most
interesting feature of the diphosphonic acid dianion is the dimer
formation between two such molecules by means of O-H‚‚‚O
hydrogen bonding (Figure 3). The hydrogen H2A attached to
the oxygen (O4A-H2A) of the symmetry generated unit has a
strong intermolecular interaction with the oxygen O2(P1-O2).
Similarly the hydrogen H2AA(O4-H2AA) also interacts in an
intermolecular manner with O2A(P1A-O2A) generating a cyclic
12-membered ring. The hydrogen bonding parameters are
summarized in Figure 3 and are perfectly consistent with known
O-H‚‚‚ O interactions;12 thus, the O(2)-O(4A) distance is 2.424
Å and the O2-H2A-O4A angle is 162°. The 12-membered
acid anhydride.11 The formation of the anion in 3 presumably
occurs by the condensation of phenyl phosphonic acid generated
insitu by the hydrolysis of 1. Evidence for the formation of
phenylphosphonic acid comes from 31P{1H} NMR data (vide
supra). The geometry around each phosphorus center in the
diphosphonic acid anion is tetrahedral. Each phosphorus is
connected to three oxygen atoms and a phenyl substituent. Thus,
P1A is attached to the O2(P-O-) with a bond distance of 1.528
Å. In contrast the P1-O1(PdO) distance is 1.468 Å. The latter
is analogous to PdO distances found in the literature; thus, in
Ph2P(O)NMe2 and Ph2P(O)(OH) the observed PdO distances
are 1.47 and 1.45 Å, respectively.12 The P1-O3 and the P2-
O3 bridging distances (P-O-P) are 1.603 and 1.615 Å and
(11) Kilian, P.; Jiritouzin, Marek, J.; Woollins, J. D.; Novosad, J. Main
Group Chem. 1996, 1, 425.
(12) Corbridge, D. E. C. In The Structural Chemistry of Phosphorus;
Elsevier Scientific Publishing Company: Amsterdam, 1974.

6060 Inorganic Chemistry, Vol. 40, No. 23, 2001
Notes
ring are out of the plane; thus, O3, O4, and O2A are on one
side of the plane while O3A, O2, and O4A lie on the other
side. Interestingly the diphosphonic acid anion dimer interacts
with the two cation subunits through N-H‚‚‚O interactions
involving the NH of the pyrazole ligand in the cation and the
PdO units of the anion. Thus, P1-O1 is involved in hydrogen
bonding with one pyrazolyl group N4-H4 while P2-O5 is
involved in hydrogen bonding with two pyrazolyl groups N6-
H6 and N2-H2.
In conclusion we describe the metal assisted hydrolysis of
P-N bonds involving phosphorus pyrazolides PhP(O)(3,5-Me2-
Pz)2, 1, and Ph2P(O)(3,5-Me2Pz)2, 2. A novel feature of the
interaction of 1 with PdCl2(C6H5CN)2 is the formation of an
unusual diphosphonic acid anion.
Figure 3. ORTEP plot of the 12-membered ring formed by the phenyl
diphosphonic acid anion dimer linked through hydrogen bonding.
Thermal ellipsoids at 50% probability. Important bond lengths (ang-
stroms) and bond angles (degrees) are P(1)-C(1) 1.793(6), P(1)-O(1)
1.468(4), P(1)-O(2) 1.528(3), P(1)-O(3) 1.603(3), P(2)-C(7) 1.790(5),
P(2)-O(3) 1.615(3), P(2)-O(4) 1.488(3), P(2)-O(5) 1.491(3), O(4)-
H(2AA) 1.02(6), H(2AA)- - - -O(2A) 1.43(6), O(4)‚‚‚O(2A) 2.424(5),
C(1)-P(1)-O(1) 112.2(3), C(1)-P(1)-O(3) 101.5(2), C(1)-P(1)-
O(2) 109.5(2), O(1)-P(1)-O(2) 114.4(2), O(1)-P(1)-O(3) 112.9(2),
O(2)-P(1)-O(3) 105.4(2), C(7)-P(2)-O(3) 104.7(2), C(7)-P(2)-
O(4) 107.8(2), C(7)-P(2)-O(5) 111.3(2), O(3)-P(2)-O(4) 105.2(2),
O(3)-P(2)-O(5) 109.1(2), O(4)-P(2)-O(5) 117.8(2), P(1)-O(3)-
P(2) 130.9(2), and O(4)-H(2AA)-O(2A) 162(5).
Acknowledgment. We are thankful to Department of
Science and Technology (India) for financial support. S.K. is
thankful to the Council of scientific and Industrial Research
(India) for a Senior Research Fellowship.
Supporting Information Available: X-ray crystallographic file in
CIF format for the structure determination of 3, two figures of 4 with
metric parameters, and a DIAMOND view of the entire fragment of 3
within the unit cell. This material is available free of charge via the
Internet at http://pubs.acs.org./
ring is puckered and the phosphorus atoms P(1), P(2), P(1A),
and P(2A) form a single plane. The rest of the atoms in the
IC010624L