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Arene-Metal Clusters Metal Atom-Bis(arene)metal Solution Phase Chemistry.

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Arene-Metal Clusters: Metal Atom-Bis(arene)metal
Solution Phase Chemistry""
By Geoffrey A . Ozin* and Mark P. Andrews
Liquid organornono-['], di-Iz1and trimetallic polymers'31
have recently been synthesized at 250 K from transition
metal atoms and poly(methylphenylsiloxane) (DC 5 10).
Subsequent experiments led to the discovery of liquid polymer-stabilized parent members of series of homologous
homo- and heterometallic c l u ~ t e r s ~ ~ . ~ ~ .
We have now investigated the initial stages of cluster
formation in DC 510 and similar systems, whereby aggregates of composition (arene),M, are formed. The procedure employed in this study involved the reaction of pure
samples of bis(to1uene)vanadium 1 or bis(to1uene)chromium 2 in methylcyclohexane solution at 140-160 K with
vanadium or chromium atoms (metal atom microsolution
method)[I2].Since the dimetal compounds 3-5 absorb at
considerably longer wavelengths than the metal ligand
charge transfer (MLCT) bands of complexes 1 and 2,
reactions can be followed by UV spectroscopy.
The absorption spectra of purified samples of 1 and 2
(synthesized both by Fisher-Hafner and metal atom methods) show very intense MLCT transitions at 324 and 318
nm, respectively. A solution of 1 in methylcyclohexane at
140 K reacts with V atoms to give the divanadium com1 reacts
pound 3,which absorbs at 453 nm (Scheme
with Cr atoms to give the heterodimetallic species 4, which
absorbs at 420 nm. The latter wavelength is the same as
that attributed to CrV produced by co-condensation of
atomic C r and V into D C 510 (250 K)12-41.
Q
* &L
Scheme 1.
Similarly, C r and V atoms react with the complex 2; 2
reacts with C r to give 5 , which absorbs at 405 nm, paralleling the observations made for the Cr/DC 5 10 ~ y s t e m ~ ~ , ~ ] .
Since we found no evidence for free arene or metal displacement reactions, the dimetallic species 3-5 were
[*] Prof. G. A. Ozin, M. P. Andrews
Lash Miller Chemistry Laboratory, University of Toronto
80 St. George Street, Toronto, Ontario, Canada MSS IAl
The generous financial assistance of the Natural Science and Engineering Research Council of Canada's Operating and Strategic Energy Programmes is greatly appreciated. M. A . also acknowledges the support of
the Ontario Provincial Government.
0 Verlag Chemie GmbH, 6940 Weinheim, 1982
Received: September 17, 1981 [Z 13b IE]
German version: Angew. Chem. 94 (1982) 219
The complete manuscript of this communication appears in:
Angew. Chem. Suppl. 1982. 381-392
[ I ] P. L. Timms, C . G. Francis, J Chem. SOC.Chem. Commun. 1977. 466; J .
Chem. SOC.Dalton Trans. 1980. 1401.
121 C. G. Francis, H. X. Huber, G. A. Ozin, J . Am. Chem. SOC.I01 (1979)
6250.
[3] C. G. Francis, H. X. Huber, G. A. Ozin, Angew. Chem. 92 (1980) 409:
Angew. Chem. Int. Ed. Engl. 19 (1980) 402.
141 C . G. Francis, H. X. Huber, G. A. Ozin. fnorg. Chem. 19 (1980) 219.
(121 G. A. Ozin, C. G. Francis, H. X. Huber, M. P. Andrews, L. F. Nazar, J.
Am. Chem. SOC.103 (1981) 2453.
By Christine Bauer, Ernst Guggolz.
Wolfgang A . Herrmann *, Gangolf Kriechbaum, and
Manfred L. Ziegler
3L
212
Scheme 2.
The Cycloaddition of Carbonyl-Flanked
Methylene BridgesA Novel Method for the Synthesis of Metallacycles**
r-
[**I
probably formed by direct addition of a metal atom to the
metal center of (toluene),M.
Based on our new results we propose that arene-stabilized dimetal complexes are produced via one-step addition
of a metal atom to a bis(arene)metal target center, and that
formation of dimetallic, trimetallic and higher clusters in
DC 510 is a process proceeding from a parent bis(arene)transition-metal complex to higher nuclearity metal
clusters as shown in Scheme 2.
Carbene additions to metal-metal multiple bonds using
diazoalkanes as starting compounds usually lead without
difficulty to dimetallacyclopropanes. We now report on an
exceptional case-the first cycloaddition of ketocarbenes
to a coordinatively unsaturated carbonylmetal compound.
According to earlier finding^^'.^.'.'^'^ it was expected
that a-diazoketones 2a-d would react with the dirhodium
compound 1 to form the dimetallacyclopropanes 3a-d. Indeed, 1 reacts rapidly with 2a-d at -40 to + 2 5 " C with
quantitative elimination of N2, but, instead of 3a-d, their
novel constitutional isomers 4a-d are formed exclusively
(isolated yields 80-95%). A single crystal X-ray structural
analysis was carried out on 4a (Fig. 2).
Figure 2 shows that the ketocarbene derived from 2a,
beyond conventional p,q'-fixation to the Rh=Rh bond of
[*] Prof. Dr. W. A. Herrmann [ +], Ch. Bauer, G. Kriechbaum
lnstitut fur Anorganische Chemie der Universitat
Universitatsstrasse 3 I, D-8400 Regensburg 1 (Germany)
Prof. Dr. M. L. Ziegler, E. Guggolz
Anorganisch-chemisches Institut der Universitat
Im Neuenheimer Feld 270, D-6900 Heidelberg 1 (Germany)
[ '1 New address: lnstitut fur Anorganische Chernie der Universitat
Niederurseler Hang, D-6000 Frankfurt am Main 50 (Germany)
[**I Part 25 of the series, Transition Metal-Methylene Complexes. This work
was supported by the Fonds der Chemischen Industrie, The Deutsche
Forschungsgemeinschaft, and the Chemische Werke Hiik-Part 24:
111.
0570-0833/82/0303-0212 $ 0 2 . 5 0 / 0
Angew. Chem. In!. Ed. Engl. 21 (1982) No. 3
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