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Isocyanide Complexes of Thorium and Uranium Halides.

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J5,,= 5.5; J2,6
* 1;
(brD) (M)
J,,,=8.5; J4,,=4.0;
J5,,=5.8; Js,,sb=12.5;* J5,sb-4
J,,,=7.5: J4,,=35;
[a] Satisfactory elemental analyses were obtained.
[b] In ethanol.
[c] In CCI,, cpd. ( 4 a ) in C,D, (+ 50°C), cpd. ( 5 a ) at 220 MHz (+60°C), cpd. (7) at +6O"C, cpd. (8) in CClJC,D,.
Received: February 3,1971 [Z 363 IE]
German version: Angew. Chem. 83,292 (1971)
[I]Photochemical Transformations, Part 43.-Part
42: H. Prinzbach, W Auge, and M . Basbudak, Helv. Chim. Acta, in press.
121 H. Prinzbach, W Eberbach, and G . u. Veh, Angew. Chem. 77, 454
(1965); Angew. Chem. internat. Edit. 4,436 (1965).
[3] H . Prinzbach and M . Klaus, Angew. Chem. 81,289 (1969);Angew.
Chem. internat. Edit. 8, 276 (1969).
[4] H. Prinzbach, M . Klaus, and W Mayer, Angew. Chem. 81, 902
(1969); Angew. Chem. internat. Edit. 8, 883 (1969); further literature
cited therein.
[ 5 ] Intermolecular Aziridine-Olefin Cycloadditions see: R. Huisgen,
W Scheer, and H.Huber, J.Amer. Chem. SOC.89,1753 (1967);H. Nozaki,
S . Fujita, and R . Noyori, Tetrahedron 24, 2193 (1968).
[6] See e. g . R. Huisgen, L. Mdbius, G. M i i k , H . Stangl, G. Szeimies,
and J . M . Vernon, Chem. Ber. 98,3992 (1965);P. Scheiner, J. Org. Chem.
30, 7 (1965); H. Tanida, I: rSuji, and I: h i e , ibid. 31, 3941 (1966).
[ 7 ] Cf. A . G . Anastassiou, J. Org. Chem. 31, 1131 (1966).
t a l k compounds. With one exception['1,the ligands in all
the actinoid organometallic compounds hitherto described
are in a negative oxidation state relative to the actinoid
atom'']. We have studied complexing with neutral ligands
to form stable actinoid-carbon compounds and now
report on the first isocyanide complexes of actinoids that
contain no stabilizing x ligands such as are found in
(C,H 5)3 U. CNC6H ".
Reaction of uranium tetraiodide (0.75 g, 1 mmole) with
cyclohexyl isocyanide (1.25 ml, 10 mmoles) in anhydrous
n-hexane at -5°C for 80h, followed by filtration, washing
of the residue with n-hexane (20 ml), and drying in vacuo
(lo-, torr) - all operations being performed at -5°C gave tetraiodotetrakis(cyclohexy1 isocyanide)uranium(rv),
By Franz Lux and U.-E. Bufe"]
The compound is not noticeably sensitive to oxygen, but
extremely so toward moisture. It can be kept for some
time at O'C, but gradually turns brown at room temperature. This aging process also results in a considerable
reduction in solubility. The fresh complex is hardly soluble
in n-hexane, moderately soluble in benzene, and dissolves
readily in chloroform, acetone, methanol, etc. The initially
yellow solutions gradually deposit a dark brown precipitate.
In discussions of the bonding of actinoids particular interest attaches to the range of existence of their organome-
The instability of the compound in solution is also apparent from the following observations:
Isocyanide Complexes of Thorium
and Uranium Halides[**'
Prof. Dr. F. Lux and Dip].-Chem. U.-E. Bufe
Institut fur Radiochemie der Technischen Universitat Munchen
8046 Garching bei Miinchen (Germany)
This work was supported by the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen Industrie.
1) Reaction of uranium tetraiodide with a solution of
cyclohexyl isocyanide in a small volume of benzene
furnishes the compound directly in the solid state in the
reaction mixture. However, owing to the partial decomposition of the portion dissolved in benzene the product
A n g e w . C h e m . internat. E d i t .
Vol. 10 (1971) / N o . 4
obtained after filtration and washing in benzene is probably
less pure than that prepared in hexane suspension.
The Position of Equilibrium in Vinylogous
Two-step Redox Systems
2) Reaction of uranium tetraiodide with cyclohexyl isocyanide in chloroform rapidly yields an orange-yellow
solution. The complex is precipitated by addition of carbon
tetrachloride or n-hexane. These products are dark in
color and not analytically pure.
By Siegfried Hunig, Friedrich Linhart, and
The complex closely resembles Pd(CNC,H,
chemical and physical properties.
in its
In the IR spectrum (KBr disk) the v(NC) band appears at
2190 cm-' and is thus shifted by 55 cm-' toward higher
wave numbers (C,H,,NC:v(NC)=2135 cm- '14]), in full
agreement with the general tendency of v(NC) to be shifted
toward higher frequencies or considerably less toward
lower frequencies in isocyanide complexes having a positively charged metal atom than in metal(0) complexes[51.
This suggests that the uranium-carbon bond has considerable o-donor character. In the limiting case of a pure
o-donor bond of isocyanide[6] in (C,H,),B.CNC,H,
(v(NC)= 2255 cmthe bond shift toward higher wave
numbers amounts to 120 cm-'. In UI,(CNC,H,,), the
U-C bond therefore has a back-bonding component.
In agreement with the argumentation above, v(NC)
=2160cm-' is shifted only 25 cm-' toward higher wave
numbers in (C,H,),U.CNC,H,
which is a U"' complex.
Thus, as suggested by the ready oxidation of U"' to U'",
a relatively large contribution by uranium +isocyanide
back bonding can be assumed['].
If IR measurements are repeated on the same sample the
intensity of the characteristic v(NC) band decreases until
the band finally disappears altogether. At the same time
the KBr disk turns dark and loses its isocyanide odor.
Similarly, thorium tetraiodide, uranium tetrabromideL8],
uranium tetrachloride, and uranyl chloride react with
cyclohexyl isocyanide in n-hexane to give ivory-colored
complexes having v(NC)=2194,2193,2196 and 2213 cmrespectively.
Received. January 14, 1971 [Z 365 IE]
German version: Angew. Chem. 83,294 (1971)
[l] 8. Kanellakopulos, E. 0. Fischer, E . Dornberger, and F. Eaumgiirtner, J. Organometal. Chern. 24, 507 (1970).
[2] L. T. Reynolds and G. Wilkinson, J. Inorg. Nucl. Chem. 2, 246
(1956); K . W. Eagnall and J . L. Baptrsta, ibid. 32, 2283 (1970); E. 0.
Fischer and Y. Hristidu, Z . Naturforsch. 176, 275 (1962); F. Eaumgartner, E. 0 . Fischer, B. Kanellakopulos, and P. Laubereau, Angew.
Chem. 77, 866 (1965); 78, 112 (1966); Angew. Chem. internat. Edit. 4,
878 (1965);5, 134 (1966); A . Streitwieser, Jr. and U . Muller-Westerhoc,
J. Amer. Chern. SOC.90,7364 (f968); D.G. Karraker, J . A . Stone, E. R .
Jones, Jr., and N . Edelstein, ibid. 92, 4841 (1970); R. D . Ammon, B.
Kanellakopulos, and R. D. Fischer, Radiochim. Acta I f , 162 (1969);
G. Lugli, W. Marconi, A . Mazzei, N . Paladino, and U . Pedretti, Inorg.
Chim. Acta 3,253 (1969); M . L. Anderson and L. R. Crisler, J. Organometal. Chem. 17, 345 (1969); G. Yagupsky, W Mowat, A . Shortland,
and G. Wilkinson, Chern. Commun. 1970, 1369; P. G. Laubereau and
J . H . Burns, Inorg. Chem. 9, 1091 (1970); Inorg. Nucl. Chem. Lett. 6,
59 (1970); P. G. Laubereau, ibid. 6,611 (1970).
131 E . 0. Fischer and H . Werner, Chem. Ber. 95, 703 (1962).
[4] B. Crociani, T. Boschi, and U . Belluco, Inorg. Chem. 9,2021 (1970).
[5] L. Maiatesta and F. Bonati: Isocyanide Complexes of Metals.
Wiley, New York 1969, pp. 25K
[6] F. Eonatr, G. Mingherti, and R. Leoni, J. Organometal. Chem. 25,
233 (1970).
171 G . Hesse, H. Witte, and G. Biltner, Liebigs Ann. Chem. 687,9 (1965).
[8] Unpublished work by A . Kiihnl.
A n g e w ~Chem. inrernat. Edit. / Vot. 10 (1971)
1No. 4
Dieter Scheutzow"'
Redox systems of general structure (1) allow one-electron
transfers in two discrete
whereby the redox
equilibrium [eq. (I)] can lie strongly on the side of the ra( K so far up to lo9).
dical cation ("~iolene"[~])
' (1) red
red + ox+2sem
K = [sem]'/[redJ [ox]
Using previously estimated values[51as a starting point for
further examination of such systems, P. Cursky and R .
Zuhradnik[61 have been able to detect a linear relationship
between log K of vinylogous systems ( 1 ) and the change
of K electron energy calculated according to
+ Ed':
if it is assumed that solvation effects can be neglected.
This assumption holds true in the case of the previously
investigated systems ( 1 ) (n = 1 to 3), in which X is a part of
an (aromatic) ring[,].
In order to investigate the behavior of K systems which are
not directly coupled to aromatic rings, we synthesized the
vinylogous compounds (2)redand (2)0x(n - 1=m = 1 to 5)
and produced (2)sem( m = 1 to 5) by comproportionation
of (2)redand (Z,JOx in acetonitrile (Scheme l)[8.91.
species (2)se,,,(m= 1 to 5) show characteristic absorption
and ESR spectra with pronounced hyperfine structure in
the case of the lower members[*].As expected the >C(CH,),
group does not participate in the delocalization of the
single electron. The ESR spectrum of (2)se,,,(m= 1) can be
readily simulated using the quoted coupling constants
without consideration of this group (Fig.
Thus (2) behaves as a pure vinylogous system, which, in
addition, exists as the longest series known to date. For
m = 1 to 3, K can be obtained from the polarogram"O'; for
m = 3 to 5 it is obtained from the extinctions of the comproportionation solution["]. As can be seen in the Table, log
H 0.0
Scheme 1. m = l to 5 ; the coupling constants given in (2)srmare valid
for m = l .
[*I Prof. Dr. S. Hunig, Dr. F. Linhart, and Dr. D. Scheutzow
Institut fur Organische Chemie der Universitat
87 Wiirzburg, Landwehr (Germany)
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thorium, halide, uranium, complexes, isocyanides
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