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Crystal Structure of P4O7.

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ture-sensitive salt (Ic) is obtained after vacuum drying; m. p.
201-202 " C (decomposition above ca. 190 "C).
Received: May 20, 1980 [Z 661 I€]
Supplemented- December 19, 1980
German version: Angew. Chem. 93. 110 (1981)
CAS Registry numbers:
( l a ) . 20055-29-2; ( l b ) , 76058-05-4; (Ic), 76058-07-6
a) P. G. Gassman, I . Nishiguchi. H:A. Yamamoro. J . Am. Chem. Sac. 97,
1600 (1975). and ref. therein; b) K. Bunge. R. Huisgen, R. Raab, Chem. Ber
10s. 1296 (1972). c) H . Schwarz. C. Koppel in S. Parai: The Chemistry of Ketenes. Allenes and Related Compounds. Wiley, New York 1980. 189.
a ) B. Samuel, K Wade, J. Chem. Sac. A 1969. 1742: h) A. Schmtdi, Chem.
Ber. IQS, 3050 (1972); c) M. 7 Reetr, W. F. Maler. unpublished results; W. F
M a w , Diplomarbeit, Universitat Marburg 1975: d ) D H R . Barton. R. D.
Bracho, A. A . L. Gunurilaka. D.A. Widdowson. J. Chem. SOC.Perkin I 1975.
a ) H. Biihme. A . Ingendoh. Justus Liebigs Ann. Chem. 1978. 1928, b) 0. Baier
in Houben- Weyl; Methoden der Organischen Chemie, Val. V W I , Thieme.
Stuttgart 1954, 407
Cleavages of ethers and aminals are analogous: a) H . Meerwein. H. MaierHuser, J . Prakt. Chem. 134. 51 (1932): b) H . Bohme, K. Hartke. Chem. Ber.
Y3, 1305 (1960); H . Bohme, A . Sickmuller, ibrd. 110.208 (1977) and references
cited therein
a) R. R. Schmidt, Synthesis 1972, 333. b) R. Huisgen in R. N . Castle: Topics
in Heterocyclic Chemistry. Wiley. New York 1969, 223.
E: 0. Wurrhwein. unpublished experiments and calculations.
Z. Janousek, H. C Viehe in H. Bohme, H G Viehe- Immium Salts in Organic
Chemistry, Wiley, New York 1976, Vol. 1, 400; H Gold, Angew. Chem. 72,
956 (1960); R. Gompper, C. S. Schneider. Synthesis lY79. 215.
MNDO calculations indicate that. for the equilibrium ( l ' ) c ' / S ) the valence
isomer (5) should be the more stable for the 1 . 1 - and 1,3 diamino derivatives,
but that (1') is preferred for the monoamino, phenyl and chloro derivatives:
E - U . WLrthwein. unpublished results
R. Huisgen, H. Stangl. H J. Slurm. R. Raab. K. Bunge, Chem. Ber. 10s. 1258
(1972) and the following publications
Crystal Structure of
By Martin Jansen and Marlen Voss~"
Dedicated to Professor Wilhelm KIemm on the occasion
of his 85th birthday
P406 opens up several preparatively interesting possibilities, which, however, have hitherto remained largely unexploited. The reason for this appears to be coupled with the
problematical isolation of pure P,061'J and the complexity of
the P4O6/P4O,, systemf2].
We report here on the reaction of P406with alkali metal
oxides A 2 0 (A = K, Rb, Cs), which proves to be unexpectedly difficult: whereas no reaction occurs at low temperature
(20-50 "C), increasing decomposition of P406 is observed
with increasing temperature above 50 "C. In the temperature
range 120-180 "C violent and uncontrolled reactions take
place. On sublimation of the heterogeneous solid reaction
products pure P407 separates in the form of translucent,
strongly refracting crystals in the warm zone 120-130 "C of
the temperature gradient (170-25 "C).
Owing to its extreme sensitivity towards moisture and oxidation the compound was prepared under argon for the Xray crystallographic and vibration spectroscopic investigations. The structure determinati~n~~l
shows that P407molecular units are present (cf. Fig. l)14]. The anisotropy of the
temperature factors can be ascribed to librational motion of
the rigid P407 groups (almost about the baricenter); the in['] Priv.-Doz. Dr. M. Jansen, DipLChem. M. Voss
Institut fiir Anorganische und Analytische Chemie der Universitat
Heinrich-Buff-Ring 58. D-6300 Giessen (Germany)
r-1This work was supported
by the Deutsche Forschungsgemeinschaft, the
Fonds der Chemischen Industrie. and Hoechst AG (sample of P,O,).
0 Verlag Chemie, GmbH, 6940 Weinherm, 1981
Fig. I. Perspective representation of a &O, molecule. Bond lengths [pm] and angles ["I in PdO, (maximum standard deviations: 0.7 pm and 0 3". respectively).
PI-01 (02: 03 04)=145.0 (159.7; 158.9: 159.5): P2-04 (05; 06)=168.2
(164.2; 164.7): P3-03 ( 0 6 ; 0 7 ) = 168.9 (166.2: 164.4); P4-02 ( 0 5 , 0 7 ) = 168.2
(164.2; 163.7): 01-PI-02
04)=114.5 (1153; 115.0); 03-PI-02
( 0 4 ) = 103 8 (103.4): 02-PI-04=
103.2; 04-P2-05
(06)=99.1 (97.9).
(07)=97.1 (98.6); 06-P3-07
= 100.3:
(98.1); 05-P4-07=
100.2: intermolecular.
03-05= 300.5; P2-02= 319.7.
tramolecular distances quoted take into account this effect151.
Despite the low positional symmetry 1 in the crystalline
state P,O, has, within the limits of error of the structure determination, the C,, symmetry to be expected for the free
molecule. One can clearly distinguish between pentavalent
(PI) and trivalent (P2, P3, P4) phosphorus by virtue of the
atomic environment (coordination number, P-0 distances).
However, the concept based on models that such molecules
are made up of
and P406 moieties with retention of the
P-0 bond lengths is reconcilable only to a limited extent
with the structural data found here. Thus, for example, the
distance from PI to the terminal 0 1 (145.0 pm) in P40, is
significantly longer than the corresponding distances in
P40,0(139.0-142.9 pm)[61.This observation points to a certain reduction in the "pentavalent character" of PI, which
could be caused by a shift of electrons from the trivalent P2,
P3 and P4 atoms linked by oxygen bridges. The marked difference in lengths of P-0 bonds from P2, P3 and P4 undoubtedly follows from the stronger interaction of 0 2 , 0 3
and 0 4 with PI. The shortest intermolecular contacts exist
between bridging oxygen atoms and correspond exactly to
the sum of the respective van der Waals radii.
Indications of a deviation from the ideal composition, as
have been described in the case of P40=x1Zb1,
have not been
observed in the case of P407.
Received: September 4, 1980 [Z 679 IE]
German version: Angew. Chem. 93, 120 (1981)
CAS Registry number:
P407. 55230-5 1-8
[ I ] D. Heinr. Z. Anorg. Allg. Chem. 347, 167 (1966).
[2] a) D. Heinr, H. Rienilz. D.Radeck, Z. Anorg. Allg. Chem. 383, 120 (1971); B.
Beagley. D. W. J. Cruickshank. T. G. Hewitf. K . H. Josr, Trans. Faraday Sac.
65, 1219 (1969); b) K. H . Jost. Acta Crystallogr. 21, 34 (1966); f7, 1593
131 A complete set of photographs indicate the space group P2,/n; a=981.7,
b=995.4. c=685.8 pm, p = 9 6 8": 2 = 4 1772 observed intensities (four-circle
diffractometer PW 1100. M o d : R=0.056.
310 (2.0); 335 (0.2): 398
141 Raman spectrum of P40, [cm - ' (rel. int.)]: 270 (IS);
(2.1); 433 (20); 535 ( I 9): 614 (0.8): 630 (lo); 660 ( I 5): 685 (0.2). 715 (0.4):
1333 ( I .3); 1345 (0.5).
[5] Y Schomaker. K. N. Trueblood. Acta Crystallogr. B 24. 63 (196R).
0570-08~3/81/~101-olO0 $02.50/0
Angew. Chem. lnr Ed Engl. 20 (1981) No. 1
161 D. W. J. Cruickshank. Acta Crystallogr. 17, 677, 679 (1964). B. Beagley, D.
W J . Cruickshank, T G. Hewitt, A. Haaland, Trans. Faraday Sac. 63, 836
(1967). The possibility of a comparison is impaired by the fact that in the case
variation of the conductivity of the cell with temperature, for
the system: Ag/NH3, NaCl/Ag, is plotted in Fig. 1.
of the dimensions of P,O,ci determined by electron diffraction the influence
of intermolecular interactions is practically missing and that the structure determinations on solid P,O,<, are relatively inaccurate and have furnished controversial results.
Electrochemical Processes in Supercritical Phases'"]
By Giuseppe Silvestri, Salvatore Gambino, Giuseppe Filardo,
Carmelo Cuccia', and Enrico Guarino""
Dedicated to the memory of Professor Raffaele Ercoli
Substances in the supercritical state, i. e. at temperatures
and pressures above their critical point, exhibit unusual solvent properties towards many organic and inorganic compounds"'. The conductivity of supercritical steam containing
various dissolved salts has been the object of considerable attention both for basic studies on the thermodynamic properties of such systems, and for the investigation of the corrosion processes taking place in power plants[*'. To our knowledge, nothing has been done to examine substances other
than water as media for electrochemical processes in the supercritical state, although the combination of the solvent
properties and fluid dynamic characteristics of such systems
make them an interesting area to explore. In this communication we report our preliminary results concerning the use
of carbon dioxide, bromotrifluoromethane, hydrogen chloride, and ammonia as supercritical solvents for electrochemical processes. Precise conductivity measurements were not
the intention of this research, which was rather an initial
evaluation of the synthetic possibilities opened by these system~'~].
Among the substances tested, a correlation between the
conductivity of the liquid phase and that under supercritical
conditions was observed e. g. a solution of tetrabutylammonium iodide in CO, was a poor conductor in the liquid, as well
as in the supercritical state. Bromotrifluoromethane, in
which electrolytes are practically insoluble, also proved to be
a very poor conductor. C 0 2 and CF3Br are consequently unsuitable as solvents for preparative electrolyses in the supercritical state, and were therefore not considered further.
Ammonia and hydrogen chloride, have high dielectric
constants and also appreciable solvent properties even in supercritical conditions (see Table 1). In a series of preliminary
Table 1. Conductivity of electrochemical systems in supercritical condition [a].
T I"C1
P [bar]
I ImA]
U [V]
0 0 0%
0 0
r [TI-
Fig. 1. The voltage o f t h e NH,/NaCI system at a constant current ( 5 mA) as a
function of temperature. Measurements were carried out in a cylindrical stainless
steel autoclave (206 cm'). Silver foil (surface area of inner and outer cylinders
8.478 and 20.41 cm2 resp.; electrode separation 0.8 cm) served as the electrodes
which were held in Teflon frames and insulated from the autoclave jacket.
A: 77.48 g/NH,, 154 mg NaCI, p=387 g/dm'
0: 64.5 g/NH3. 154 mg NaCI, p=313 g/dm'
D. 57.63 g/NH,. 154 mg NaCI, p=280 g/dm'
It was determinant, for the conductivity of the medium,
that the supercritical system should have a high density
(280-390 g/dm3) ( p at the critical point 235 g/dm3).
The curves show that the dependence of the conductivity
with temperature beyond the critical point is approximately
inversely proportional to the specific weight of the supercritical phase. Electrolyses were also performed over long periods
of time, in which up to 4000 Coulombs were passed through
the cell; it was observed that the conductivity of the system
remains substantially unchanged during electrolysis. The
data on electrolyses involving the above mentioned system,
as well as the Fe/NaCl, NH3/Fe system, are summarized in
Table 2.
Table. 2. Preparative scale electrolyses in supercritical ammonia ( Q = quantity of
charge transported).
[a] Conducting salt nBu,NI [b] Conducting salt NaCl
experiments in sealed glass capillary tubes"], it was observed
that at 50 "C NaCl was relatively insoluble in NH3 and that
the meniscus disappeared at 129 "C; preparative scale electrolyses on this system with similar electrolyte concentration,
were therefore performed at temperatures above 129 "C. The
I*]Prof. Dr. G. Silvestri, Dr. S. Gambino, Dr. G. Filardo, C. Cuccia, E. Guarino
lnstituto di lngegneria Chimica. Viale delle Sienze, Palermo (Italy)
The content of this publication is part of a dissertation by C. C. and E. G.
Angew. Chem. Inr Ed. Engl. 20 (1981) No. I
Anodic current
efficiency [%I
The anodic dissolution of silver takes place with very good
current yields. Reduction of the silver ions at the cathode resulted in a deposit of fine silver powder on all the internal
surfaces of the cell. In the case of iron, the anodic process of
dissolution of the metal accounts for only 45% of the charge
0 Verlag Chemie, GmbH, 6940 Weinherm. 1981
$ 02.50/0
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crystals, structure, p4o7
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