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Metal-Induced Decarboxylation of DiketeneЧA Novel Route to Allene Complexes[1].

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co-dimethylsiloxane) (DC 510) the cluster size (n =4, 5),
the rate of cluster formation, and stabilization are substantially enhanced. For example, when vanadium atoms are
cocondensed with benzene or toluene (matrix, 12-77 K)
two species are formed: (arene),V showing a metal-ligand
charge transfer (MLCT) absorption at L=323 nm, and
(arene),V, absorbing at 455 nm. Homo- and heterodimetallic compounds can be produced by direct addition
of a transition metal atom to bis(arene)metal (n = 1) sandwich complexes[51in solution.
Deposition of atomic Mo into liquid a,o-diphenyloligo(ethy1ene oxides) at 275 -290 K gives rise to mono-, di-,
and trimetal compounds (Lmax=318,415, and 502 nm, respectively). Clusters having nuclearity n > 3 cannot be prepared in these reaction media. Reaction of Mo with
DC510 (250 K) gives rise to two additional species: a tetraand a pentanuclear cluster (Amax = 578 and 640 nm, respectively). However, only (arer~e)~Mo,is produced when
(arene)2Mo dissolved in phenyl-free, liquid poly(dimethy1siloxane) DC200 is titrated with Mo atoms. Stable, low nuclearity clusters could not be grown in the absence of free
arene or arene functionalities in liquid media.
Kinetic analysis of the growth curves for Mo, in DC510
appears to confirm a stepwise aggregation model. Further
studies (viscometry, NMR, ESR) on the DC5lO/M system indicate (among other factors) the role played by interand intramolecular crosslinking via (arene),Mo complex
formation in stabilizing tetranuclear and higher metal clusters: for (arene),M, this decreases from n = 2 to n = 5. Loss
of the binuclear (arene),Mo2 species supported on DC510,
through diffusion-controlled aggregation follows second
order kinetics, the rate and activation energy of diffusion
being functions of metal loading (variation in crosslink
density). Thus the activation energy for the dimerization of
(arene),Mo2 supported on DC510 (290 K) at low metal
loading levels is 4.2 kcal/mol compared to a high loading
value of 14.2 kcal/mol : the respective diffusion coefficients of 3 2 . 6 ~
and 1 8 . 7 ~
cm2/s reflect the
microscopic mobility of the polymer support, which is constrained by increasing crosslinking.
These data together with results of ESR, EXAFS, SIMS,
and Raman spectroscopic studies collectively indicate that
the growth/agglomeration characteristics in the polymer
are determined by a number of effects: I ) the presence or
absence of covalently bound arene groups; 2) changes in
the microenvironment in the vicinity of the metal aggregate, where cluster size and stability are seen as determined, in part, by the dimensions and arene density of
“solvating” cavities. 3) Steric interaction between the immobilized metal aggregate, the polymer support, and the
diffusant (metal atom, covalently bound arene, or nucleation site); diffusional encounters are controlled by polymer microdynamics which are dependent both on temperature and crosslink-density. 4) Diffusional limitations which
affect the rate of penetration of metal atoms into the polymer (to contribute to cluster growth or be “removed” by
a colloid sink), cluster aggregation is also diffusion controlled. 5) Structural changes or constraints imposed on
metal aggregates or polymer as a result of binding or stabilization of macromolecules by crosslinking; such
changes will control both the number and size distribution
of clusters, determining a maximum metal loading limit
beyond which colloid formation becomes the favored
process for metal atom consumption.
The bis(arene)metal complexes are viewed as “crosslinking” and/or chain propagating agents, as well as metal nucleation sites for the production of clusters. The aggregates
Angew. Chem. Int. Ed. Engl. 21 (1982) No. 7
are, in part, “solvated” by the ether oxygen atoms of the
oligomer or polymer backbone. Evidence suggests that this
interpretation is more likely than the alternative involving
crown ether or cryptand-like ligand-M, interactions, without participation of the phenyl substituents.
Received: February 8, 1982 [Z 127 IE]
German version: Angew. Chem. 94 (1982) 551
The complete manuscript of this communication appears in:
Angew. Chem. Suppl. 1982. 1255-1264
[ I ] C. G. Francis, H. X. Huber, G. A. Ozin, Inorg. Chem. 19 (1980) 219; J .
Am. Chem. SOC.I01 (1979) 6250; G. A. Ozin, C. G. Francis, J. Mol.
Stmct. 59 (1980) 55; J . Macromol. Sci. Chem. A 16 (1981) 167.
[21 M. P. Andrews, G. A. Ozin, C. G. Francis, paper presented at ACS meeting (Petroleum Chemistry Division), Las Vegas, 1980.
131 G. A. Ozin, C. G. Francis, H. X. Huber, M. P. Andrews, L. F. Nazar, J.
Am. Chem. SOC.103 (1981) 2453.
[41 G. A. Ozin, M. P. Andrews, C. G. Francis, Inorg. Synthesis. in press.
151 G. A. Ozin, M. P. Andrews, Angew. Chem. 94 (1982) 219; Angew. Chem.
Inl. Ed. Engl. 21 (1982) 212.
Metal-Induced Decarboxylation of DiketeneA Novel Route to Allene Complexes“’
By Wolfgang A . Herrmann*, Josef Weichmann,
Manfred L. Ziegler, and Heike Pfisterer
Dedicated to Professor Klaus Weissermel on the occasion
of his 60th birthday
The synthetic potential of the readily accessible and industrially importantL2]diketene 2 has so far been overlooked in organometallic chemistry. We report here on the
metal-induced decarboxylation of this compound, which
reaction enables the facile and convenient synthesis of allene complexes.
Whereas breakdown of the diketene skeleton requires
temperatures around 550 C and yields besides ketene only
traces of allener2’, its decarboxylation takes place under
surprisingly mild conditions in the presence of carbonylmetal compounds that are labile towards ligand substitution; concomitantly, allene is incorporated into the organometal substrate. Thus, reaction of the tetrahydrofuran
complex 1 with excess diketene 2 in the temperature range
-30 to + 2 5 ” C leads cleanly, under vigorous evolution of
C02, primarily to the mononuclear q2-allene complex 3
(characterized by total elemental analysis, and by IR, ’H-
1
2
H
”
3
I+’
[*] Prof. Dr. W. A. Herrmann, J. Weichmann
Institut fur Anorganische Chemie der Universitat
Niederurseler Hang, D-6000 Frankfurt am Main 50 (Germany)
Prof. Dr. M. L. Ziegler, H. Pfisterer
Anorganisch-chemisches lnstitut der Universitat
Im Neuenheimer Feld 270, D-6900 Heidelberg I (Germany)
0 Verlag Chemie GmbH. 6940 Weinheim, 1982
0570-0833/82/0707-0551 rE 02.50/0
55 1
The high-yield secondary complexation of the free C=C
bond of 3 to the (qs-C5H5)Mn(CO)2fragment with clean
subsequent decarbonylation (1 3-5 ; 5-4
CO) can be
used in general for the straightforward synthesis of previously rarely encountered dinuclear complexes with all2].
lene
As a test-case, the reaction of diketene 2 with Fe,(C0)9
may be cited here. Analogously to 3 and SL9I,the complex
Fe2(C0),(C,H,) with an q’ :q3-allene bridge is formed almost quantitatively already at 25 “ C ; this particular compound was hitherto accessible only by reaction of
allene and Fe2(C0)9 at elevated temperatures (SOOC) and
pressures[”. Our synthetic route to bridged allene complexes also opens u p the possibility of synthesizing derivatives containing different metal centers.
+
Fig. I . Structure of the w(q* :q2)-allene complex 5 in the crystal. R,=0.029.
The angle between the plane of the V-shaped allene bridge and the Mn-Mn
vector is 48.6”. The q2:q2-coordination rules out a metal-metal bonding with
the present stoichiometry on electronic grounds; as expected the Mn-Mn
distance is greater than 380 pm.
Table 2 (selected data). Some important bond lengths [pm] and angles I”] in 5.
MnC(I) 177.8(6), MnC(2) 175.9(6), MnC(3) 214.6(3), MnC(4) 211.9(6),
C(3)C(4) 140.8(7), C(I)O(l) 116.2(7), C(2)0(2) 117.1(8); C(4)C(3)C(4‘)
129.5(0.8), C(I)MnC(2) 87.1(0.3), MnC(4)C(3) 71.8(0.3), MnC(3)Mn’
131.3(0.4)
NMR and mass spectra). The q2-allene ligand does not
fluctuate with respect to the metal-ligand bond [‘H-NMR
(270 MHz, [DaITHF, 25°C): 6 C H 2 ~ 6 . 1 9( I H), 5.66 (1 H),
2.53 (2H); 6C5H5=4.68 (SH)]. Besides 3, the dinuclear
derivatives 4 ( < 3%, already known[’]) and 5 ( < 10%) with
symmetrically bonded V-shaped q2 :q2-allene bridges (Fig.
1, Table 2) are formed.
+
Received: May 3, 1982 [Z 31 IEj
German version: Angew. Chem. 94 (1982) 545
The complete manuscript of this communication appears in:
Angew. Chem. Suppl. 1982. 1223- 1245
CAS Registry numbers:
1, 12093-26-4; 2, 674-82-8; 3, 82168-19-2; 4, 73002-71-8; 5 , 82150-25-2.
[ I ] Complex Chemistry of Reactive Organic Compounds, Part 40. This
work was supported by the Deutsche Forschungsgemeinschaft and the
Fonds der Chemischen lndustrie (Promotionsstipendium (J. W.)).- Part
39: W. A. Herrmann, J. Weichmann, B. Balbach, M. L. Ziegler, J. Organomet. Chem. 231 (1982) C69.
[ 2 ] D. Borrmann in Houben-Weyl-Miiller: Methoden der Organischen
Chemie. Band V11/4, p. 226ff., Thieme, Stuttgart 1968.
[7] X-ray structure analysis of 4 : L. N. Lewis, J. C. Huffman, K. G. Caulton, J . Am. Chem. SOC.102 (1980) 403; Inorg. Chem. 19 (1980) 1246.According to this work compound 4 is formed in unspecified yield by
means of H-/CH,+-addition upon the vinylidene precursor (p
C=CHI)[(qS-CsHS)Mn(CO)~l~.
[8] R. Ben-Shoshan, R. Pettit, Chem. Comrnun. 1968. 247; cf. R. E. Davis,
ibid. 1968, 248.
191 Unsuccessful attempts to synthesize manganese-allene complexes (e.g.
3) from free allene: cf. A. Nakamura, Bull. Chem. SOC.Jpn. 39 (1966)
543.
1121 A. Kiihn, C. Burschka, H. Werner, Organometallics I (1982) 496, and
references cited therein.
BOOK REVIEWS
An Introduction to Chemical Equilibrium and Kinetics. By
L. Meites. Pergamon Press, Oxford 1981, xiii, 549 pp.,
price E 8.95.
This book was written to serve the new type of beginners’ chemistry course at Clarkson College of Technology.
The course comprises a first semester of lectures on structure and bonding, and a second semester of lectures based
on the present book, both running in parallel with a oneyear “integrated” practical course. The book is divided
into the following chapters: Chemical Thermodynamics
and Equilibrium, Chemical Kinetics, Non-electrolyte
Equilibria, Solubility of Ionic Compounds, Acid-base
Equilibria, Complex Reactions, Redox Processes, Analytical Chemistry and Stoichiometry, Precipitation, Titration
Curves, Errors in Measurement, Activities and Activity
Coefficients, Potentiometry, and Spectroscopy. Thus, almost nothing has been left out from the field embraced by
classical chemistry.
As a physical chemist I found myself fluctuating between laughter and tears while reading this book. The
552
0 Verlag Chemie GmbH, 6940 Weinheim. 1982
laughter was a reminder of my own student days, when I
heard a world-famous organic chemist announce to his
students that “a real chemist has little use for physical
chemistry”. The tears were provoked by the way this book
treats the fundamentals of physical chemistry as “black
box” concepts. Thermodynamics are dealt with in 23
pages, and free energy occupies a page or two. Students of
chemistry are already reluctant to interrupt chemistry practicals to attend lectures on physical chemistry, and were
they to take Mr. Meites‘ book seriously, this trend could
not but be reinforced. It is inconceivable to me that a
course of study written in this superficial style can possibly
produce scientifically creative chemists. No doubt the
book can be explained in terms of the widely differing
standards encountered in colleges in the United States, not
all of which aim to foster a new generation of researchers.
The book can be recommended: for physical chemists in
search of illustrative examples; for teachers of advanced
inorganic o r organic chemistry who wish to bridge over
into physical chemistry; for undergraduate students who
OS70-0833/82/0707-0S52 $02.50/0
Angew. Chem. Inr. Ed. Engl. 21 (1982) No. 7
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