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Complexes of Molybdenum(III) with 1 3-Diketones.

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fairly large excess of trimethylchlorosilane with 1 mole of
acetamide under the same conditions produced in good yield
u carboxamide which is bis-silylated at the amide group, viz.
the hitherto unknown bis(trimethylsilyl)acetamide (I).
This is a colorless liquid (b.p. 67.SoC/30 mm) and is very
sensitive towards hydrolysis. It proved possible in the same
way t o transform acrylamide into bis(trimethylsilyl)acrylamide (2), a colorless liquid of b.p. 73.SoC/22 mm. Investigations are in progress to decide between the two
structures possible in each caw.
0
O-Si(CH
I
dSi-,andlor R . C-N-
” .
R.C..
33
Miss A. Sieburg carried out the invcstigations on the rhenium
compounds.
Refcived, December Sth, 1962 [Z 404/228 1E)
[*I At present situated in the Max-I’lanck-Institui fur Chemie
(Otto-Hahn-lnstitut)in Mainz, Gerniany.
[I] E. Weise. 2. anorg. allg. Chem. 283,377 (1956).
121 J. L. Hoardand W . B. Vincent. 3. Amer. chem. SOC.61,2849
( 1939).
[3] R. D. Peacock, Chem. and Ind. IVSS, 1453.
(41 H.Bode and W.Wen& 2.anorg. iillg. Chem. 26Y. 165 (1952).
[5] Density determination: cf. K. Srhworhau, Z. Naturforsch. 170
630 (1 962).
Si(CH3)3
‘Si(CH&
(1) R
-
CH3
Complexes of MoIybdenum(II1) with 1,3-Diketones
(2) R == H2C ICH
By DipLChem. K. Christ and Prof. Dr.
Limburg and Post [31 thought that they had prepared (I) by a
reaction between ketene and hexamethyldisilazdne,
[(H3C)3Si-NH-Si(CH3)3]. The very high boiling point
(61.5°C/0.15 rnm) differs from that of our product, and the
analytical data do not correspond to the required values; this
proves that these authors had not obtained the substance
claimed.
Received, December 4th. 1962
[Z4051229 I€]
lnstitul fur Physikalische Chemie
der Universitiit FrankfurtlMain (Germany) [*I
We have prepared the following co-ordination compounds
of trivalent molybdenum:
b -c‘
“9
“!!I I
[ I ] 17th Communication on organosilicon compounds; 16th
Communication: L. Birkofer, A. Rirrer. and H. Dickopp, Chem.
Ber., in the press.
12) L. Birkofer, A. Ritter. and H. Dickopp, Chem. Ber., in the
press.
131 W. W.Limburg and H.W. Post, Rec. Trav. chim. Pays-Bas
81, 430 (1962).
Preparation, Properties and Crystal Structure of
Potassium Hexafluorotechnetate(1V)
By Dr. K. Schwochdu and Prof. Dr. W.Herr
Arbeitsgruppe Jnstitut fur Radiochemie” der
Kernforschungsanlage Jiilich (Germany) and lnstitut fiir
Kernchemie der Universitiit K6ln (Germany) [*]
In analogy with the preparation of the corresponding
rhenium compound [I], we obtained K I (99TCF6) on melting
KzvcBr6) with K HF2. Potassium fluorotechnetate was
isolated in a pure state and in 60-70 % yield by recrystallization from water as pale pink, hexagonal platelets. The
solubility of the salt at 25 O C was 1.5 g in 100 g of water.
The absorption spectra of the (T‘CF6)2- and (ReF6)2- ions
are extensively similar in the visible, ultraviolet, and infrared
regions, as was to be expected. While the other hexahaIogen
complexes of tetravalent technetium and rhenium do not
absorb in the infrared spectral region of 4OOO-400 cm-1, an
intensive band was found for K2(TcF6) at 574 cm-1 (17.4
(z), and one for Kz(ReF6) at 550 cm-1 (18.2 (z); these are to
be assigned to the Tc-F and Re-F oscillations respectively.
The resistance of the fluorotechnetate to hydrolytic decomposition is particularly noteworthy. Chloro-, bromo-,
and iodotechnetate (IV) all undergo hydrolysis even in
weakly acid solution but (TcF~)~only in hot conc. aqueous
alkali.
According to X-ray structura1 investigations, K2ncF6)
crystallizes a t room temperature in the trigonal Kz(GeF6)
type [2] with lattice constants a = 5.807 j, 0.002 A and
c = 4.645 f 0.002 A, and is isomorphous with Kz(ReF6) [1,3]
and a modification of Kz(MnF6) [4] at low temperature.
The density of potassium fluorotechnetate was measured as
p = 3.58 f 0.01 dcm3 [4]. It follows from this and from the
crystal structure that the unit cell contains one formula
element.
Angew. Chem. internut. Edit.
VoI. 2 (1963) I No. 2
H.L. Schliifer
J=\.
h
3
where
RI
R2
CH3
CHI
GHs
GHs
CFI
CH3
CF3
CH3
GHs
GHsS
The following diketones were uscd: (I) acetylacetone [I],
(2) trifliioroacetylacetone,(3) bcnzoylacetone, (4) dibenzoylmethane, and (5) thenoyltrifluoroacetone.
The ketones (I) and ( 2 ) were treated with K3[MoIuClb] in
aqueous methanol at room tempcrature, the acid formed
being buffered with ammonium acetate. The compounds
precipitate after fairly prolonged standing. Molybdenum(lll)tris-acetylacetonate was recrystallized from a mixture of nhexane and tetrahydrofuran (2:l), while n-hexane was used
for molybdenum(l1l)-tris-trifluoroacctylacetonate.
Solubility difficulties arise with ketones (3), (4), and (5) but
can be circumvented by using a tcrnary mixture of dioxanl
methanol/water as rextion medium and ( N H & [ M o ” ~ ~ s (HzO)] as starting material. The required compounds were
then obtained by fairly prolonged and vigorous stirring at
room temperature followed by evaporation of the solvent in
vacuo. The products are deep rcd-brown to black. They
dissolve in organic solvents such as benzene, tetrahydrofuran,
CC14, and partially in n-hexane to give deep red-black
solutions. Scveral of the compounds become hot spontaneously in air. As the size of the organic ligand increases, the
tendency to give tarry products during this process grows.
All manipulations must be carried out under highly purified
nitrogen, and it is essential to remove carefully any traces
of dissolved oxygen from the solvents.
The preparation of the compounds mentioned and the
results of investigations of their optical and magnetic properties will be published in the near future.
Received, Decemher 7th. 1962 [Z4101236 IEl
[I] Molybdenum(llI)-trisacetylacetonate has also been prepared
by M . L. Larson and F. W. Moore, J. inorg. Chem. 1.856 (1962).
Barium Halogenonitrides
By Prof. Dr. P. Ehrlich, Dr. E. Koch
and DipLChem. V. Ullrich
Jnstitut f i r Anorganischc und Analytische Chemie
der Univcrsit‘it GieBen (Germany)
Continuing an earlier investigation [I] of the chloronitrides
of alkaline earth metals, in which the existence of the compounds CazNCl and BazNCl was verified, the systems
97
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diketones, complexes, molybdenum, iii
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