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Magnetic Behavior of Alkali-Metal Tetroxocobaltates(v).

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The Crystal Structure of 1,6 :8,13-Propanediylidene[14lannulene
Magnetic Behavior of Alkali-Metal
Tetroxocobaltates(v)
By Gianluigi Casalone, Angelo Gavezzotti, Angelo Mugnoli,
and Massimo Simonetta I*]
By Claus Brendel and Wilhelm Klemm 1*I
The relationship between the aromatic character and the form
of the bridged annulene ring in 1,6 : 8,13-propanediylidene[14]annulene 111 is of considerable interest.
1,6:8,13-propanediylidene[l4]annulene, m.p. 180-181 O C ,
crystallizes in the orthorhombic space group Fdd2 (Ci”,, with
16 molecules in the unit cell, a = 19.47, b = 36.37, c = 6.58 A,
dX-ray= 1.244, dexp= 1.248 g cm-3. The intensities of about
1300 independent reflections were recorded on a linear automatic diffractometer using M O K radiation.
~
The orientation of one molecule in the unit cell was determined by an automatic comparison between the experimental
three-dimensional sharpened Patterson synthesis calculated
near the origin and the intramolecular vector distributions
calculated for a plausible molecular model rotating about
three mutually perpendicular axes [21. The position of the
reference molecule in the unit cell was then determined by
systematic comparison between observed and calculated
structure factors, while shifting the oriented model along x
and y (z being a polar axis). Some cycles of full-matrix isotropic least-squares refinement on the 826 reflections having
I > 2 B ( I ) led to an R index of 11.5 %. Further refinement is
in progress taking into account the anisotropy of the thermal
vibration.
The molecular conformation (Fig. 1) is very close to the
mm2 symmetry, the differences being of the order of the
estimated standard deviations as calculated at this point of
the refinement. The geometrical features along the annulene
perimeter are similar to those previously found for 1,6 : 8,13bisoxido[l4]annulene 131.
Dedicated to Professor Eugen Miiller on the occasion of his
65th birthday
A few years ago we reported on potassium tetroxocobaltate(v) [11. Although a magnetic moment of >4.9 pg expected for
Cov having the 3d electron configuration (e)*(t2)2 with tetrahedral coordination was found for solid solutions of K3Co04
with K3P04, considerably lower values were observed for
pure K3Co04, possibly because of interactions between the
c003- groups.
Since such interactions should be less effective in rubidium
and cesium tetroxocobaltate(v) we have now studied the
magnetic behavior of these compounds. They were prepared
by heating 3 : 1 mixtures of RbOo.7 and CoO1.5 at 35OoCfor
4 h or at 28OoC for 46 h, and 3 : 1 mixtures of Cs00.5 and
CoO1.5 at 3OO0C for 2-3 h, respectively, under approx.
0.5 atm of 0 2 in a sealed tube. The black products of uniform appearance resulting on quenching to room temperature
react with water in the same way as K3Co04. The change in
weight incurred during reaction also corresponds to the
formation of Rb3Co04 and Cs3CoO4. The molar volumes of
97 and 112cm3 calculated from the densities of 3.90 and
4.65 g cm-3 are consistent with the molar volume of K3Co04
( d = 2.74 g cm-3, VM = 88 cm3). The debyeogram permits no
conclusion whether the three compounds are isotypic.
The magnetic behavior of the new tetroxocobaltates(v) is
similar to that of K3Co04, as can be seen from the tabulated
effective moments:
As expected, the p e f f values increase on going from the K
compound to the Cs compound, i.e. the anionic interactions
decrease in magnitude. However, the value of p e f f recorded
for the Cs compound at room temperature is still far removed
from the moment predicted for Cov .
Received: A p r i l 20, 1970
I
Z 216 IEI
German version: Angew. Chem. 82, 519 (1970)
Fig. 1 . Crystal structure of 1.6:8,13-propanediylidene[l4]annulene.
a) Absolute values of torsion angles in the annulene perimeter. b) Mean
values of symmetrically equivalent bond lengths and angles.
Received: February 9. 1970
IZ 214e IEI
German version: Angew. Chem. 82, 516 (1970)
Publication delayed at authors’ request
[*I Dr. G. Casalone, Dr. A. Gavezzotti, Dr. A. Mugnoli, and
Prof. Dr. M. Simonetta
Istituto di Chimica Fisica della Universita
Via C. Saldini, 50
1-20133 Milano (Italy)
[I] E . Vogel, A . Vogel, H.-K. Kubbeler, and W. Sturm, Angew.
Chem. 82, 512 (1970); Angew. Chem. internat. Edit. 9, 514
(1970); we are grateful to Prof. E . Vogel for supplying us with
crystals of 1,6:8,13-propanediylidene[l4]annulene.
[2] Program written by G . Filippini and C. M . Gramaccioli,
to be published.
[3] P . Ganis and J . D . Dunitz, Helv. Chim. Acta 50, 2369
(1967).
Angew. Chem. internat. Edit.
Vol. 9 (1970) f No. 7
____
[*I C. Brendel and Prof. Dr. W. Klemm
Anorganisch-chemisches Institut der Universitat
44 Miinster, Gievenbecker Weg 9 (Germany)
[l] C. Brendel and W. Klemm, Z. anorg. allg. Chem. 320, 59
(1963).
A Stable Aroxyl Radical of the
Heteroaromatic Series
By Hans-Joachim Teuber, Giinther Schutz, and
Hans-Joachim Gross [*I
Dedicated to Professor Eugen Miiller on the occasion of his
65th birthday
Of the isomeric hydroxypyridines, the 3-hydroxy compound
shows the closest resemblance to phenol. The phenolic
character has now been effectively established by the successful dehydrogenation of its 2,4,6-triphenyl derivative (2) to a
stable radical ( 3 ) .This is the first radical of its kind in the
heteroaromatic series.
We have synthesized (2) from methoxychalcone and phenacylpyridinium bromide via the methyl ether (I).
519
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