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Photochemical Synthesis of Bis(1 3-diene)monocarbonyliron Compounds.

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[SO] R. H . Holm, A . Chaki-asory, and G.O. Dudek, 1. Amer. Chem. Soc.
85, 821 (1963).
[81] G. W Eceretr, Jr. and C.R. Powers, Inorg. Chem. 9, 521 (1970),
and further literature cited therein.
[82] K . Mislow and M . Raban, Top. Srereochem. 1, 1 (1967).
[83] A4. can Gorkom and G . E . Hall, Quart. Rev. Chem. SOC.22,14
(1968).
[84] J . D . Ruddick and B . L . Shaw, J. Chem. Soc. A 1969, 2964, and
earlier publications.
[ 8 5 ] H Brunner and E. Schmidt, Angew. Chem. 81, 571 (1969); Angew.
Chem. internat. Edit. 8, 616 (1969).
[86] H . Brunner, H.-D. Schindler, E. Schmidt, and M. Vogel, J. Organometal. Chem. 24, 515 (1970).
[87] J . A . Pople, W G . Schneider, and H . J . Bernstein: High-resolution
Nuclear Magnetic Resonance. McGraw-Hill, New York 1959, p. 218.
[88] H . Strehlow: Magnetische Kernresonanz und chemische Struktur. Steinkopf, Darmstadt 1968, p. 102.
C 0 M M U N I CAT10N S
Photochemical Synthesis of
Bis( 1,3-diene)monocarbonyliron Compounds
By Ernst Koerner von Gustorf, Jiirgen Buchkremer, Zorka
Pfajjfer, and Friedrich- Wilhelm Greuels[']
of ligands and shows that the CH,-CH,
groups of the
cyclohexadiene are turned towards the carbonyl group.
This substantiates the assignment of structure (2a) to
compound ( 2 ) .
Thermal reaction of butadiene with iron carbonyls results in replacement of at most two CO ligands by
butadienel']. Thus butadiene and Fe(CO), react in an
autoclave at 140"C to give butadienetricarbonyliron ( I )
in 42 % yield"].
The photochemical preparation of ( 1 ) at 20 0C[3*4J
gives
higher yields. During a study of this reaction we found
that bis(butadiene)monocarbonyliron (2), the first example of a new type of olefincarbonyliron complexes[5], is
formed as by-product. Under appropriate conditions ( 2 )
becomes the main product (see experimental part). The
complex crystallizes from pentane at - 78 "C as orange-red
tetragonal crystals of several centimeters length (m. p.
[email protected]"C, decomp.). The crystals are stable in air at
room temperature.
Irradiation of Fe(CO), with isoprene affords bis(isoprene)monocarbonyliron (4) (m.p. 99-104 "C, decomp. ;
~c,,=1980 cm-I). According to the 'H-NMR spectrum
the two CH, groups in ( 4 ) are chemically equivalent['01.
Of the two isomers (4a) and (4b) only one is apparently
present; consideration of models indicates that (4a) is
the more likely structure as it involves less interaction
between the two isoprene units.
0
0
5:
The structure of (2) follows from the 'H-NMR spectrum,
whose splitting pattern is superimposable with that[@
of ( I ) , thus establishing the symmetrical arrangement of
the butadiene units. This assumption is confirmed by the
space group Pa22,mfound by X-ray structure a n a l y s i ~ [ ~ . ~ ] .
By analogy with the position of the butadiene"] in ( l ) ,
the former of the two alternatives (2a) and (2b) appears
the more probable.
The diene-iron bond, e.g. in (2), can be cleaved again
photochemically; in the presence of 1,3-cyclohexadiene
Apart from the molecular ion, the mass spectrum of (2)
compound ( 3 ) is formed as a result of ligand exchange.
shows fragments that arise from the successive loss of
CO and two butadiene units. As expected, only one CO
The bis(diene)monocarbonyliron compounds are isostretching mode at 1984.5 cm-' (in n-hexane) is seen
steric with the starting materials - such as, for example,
in the IR spectrum.
bis(l,5-cyclooctadiene)nickel(0) - for the preparation of
nickel catalysts used in the oligomerization of butaUnder the conditions worked out for ( 2 ) , Fe(CO), rediene["]. On coordination with ,CO iron becomes foracts photochemically with 1,3-cyclohexadiene to give a
mally isoelectronic with nickel(0); bis(diene)monocar40
yield of bis(l,3-cyclohexadiene)monocarbonyliron
bonyliron complexes therefore also catalyze the oligo(3) that also forms orange-red crystals (m. p. 134-136 "C;
merization of butadiene. In the presence of n-donors
decomp. ; \icn= 1964.5 cm- I ) . The 'H-NMR spectrum
such as phosphanes butadiene can be dimerized to 4-vinylagain exhibits coupling constants corresponding to those
1-cyclohexeneand 1,5-cyclooctadieneby catalytic amounts
observed for 1,3-cyclohexadienetricarbonyliron[g'.X-Ray
of e.g. ( 2 ) or (3) at temperatures of about 100°C.
structure analysis[" confirms a symmetric arrangement
When no phosphane is present, trimerization to 1,5,9cyclododecatriene and other butadiene trimers is ob["I Dr. E. Koerner von Gustorf, DipLChem. J. Buchkremer,
served'"]. The bis(diene) complexes of other transition
DipLIng. Z. Pfajfer, and Dr. F.-W. Grevels
metals
of corresponding structure and electronic conMax-Planck-Institut fur Kohlenforschung
figuration
should also fulfill the requirements for catalytic
Abteilung Strahlenchemie
activity.
433 Miilheim-Ruhr, Stiftstrasse 34-36 (Germany)
4:
>;
260
Angew. C h e m . internat. Edit. / Vol. 10 (1971) / No. 4
Procedure for the preparation of (2) :
Fe(CO), (0.05 mole) and butadiene (1 mole) in pentane
(300 ml) are irradiated at 35 "C under argon for 48 h
in an immersion-lamp apparatus with internal and external cooling using a high pressure mercury arc lamp,
Philips HPK 125 W. The coolant is first passed through
the external cooling mantle and then through the internal one. The temperature gradient causes the product
(2) to crystallize at the outer wall of the reaction vessel.
After irradiation, the solution is allowed to warm to room
temperature whereupon (2) dissolves and can be freed
from small amounts of brown decomposition products
by inverse filtration. On renewed cooling of the filtrate
to -78 "C, crystalline (2) of analytical purity is precipitated in 85-90
yield (based on Fe(CO),).
~
<:
group P21212, along {Ol)with the following cell constants: a=17.089+_0.0005, b=8.495&0.0004, c=7.545
+0.0004A; Z = 4 ; d(calc)=1.48 g ~ m - ~ .
The molecular structure was deduced by the heavy atom
method from 1697 diffractometer data and, including the
unequivocally located hydrogen atoms, refined anisotropically to an R factor of 3.3%.
Unlike bis(l,3-butadiene)monocarbonyliron[21(a= 7.76,
c= 7.33A), whose space group P42,m requires the molecule to have C, symmetry, complex ( 1 ) is chiral and has
only approximately m-symmetry. In spite of their fairly
close contact to the carbonyl group, the C, rings are
arranged as shown in Fig. 1 ; Fig. 2 shows a view along
the Fe-CO axis.
Received: November 9,1970 [Z 349a IE]
German version: Angew. Chem. 83.249 (1971)
Publication delayed at authors' request
0
9
[I] H . D.Murdoch and E. Weiss, Helv. Chim. Acta 45, 1156 (1962).
[2] R . 8.King, Organometal. Syn. I , 128 (1965).
[3] E. Koerner con Gustorfand F.-W Grecels, Fortschr. Chem. Forsch.
13,366 (1969).
[4] E . Koerner uon Gustorf; Z . Pfajjer, and F.-W Grecels, Z. Naturforsch. 266, 66 (1971).
[5] R. E. Davis, G. L. Cupper, and H . D. Simpson, Amer. Crystallogr
Assoc. Summer Meeting, August 1970, Ottawa, Abstr. N 4, mention
an X-ray structure analysis of (21, which has apparently also been
prepared at the University of Texas, Austin (USA). Note added in pro05
Meanwhile (2) has also been prepared by reaction of butadiene with
ferric chloride in ether at -78°C in the presence of isopropylmagnesium chloride and saturation of the rcaction mixture with carbon
monoxide. Apparently this process is witable only for the preparation
of small amounts of the complex; the yield is about 30% [ A . Carbonaro
and A . Greco, J. Organometal. Chem. 25,477 (1970)l.
[6] The 'H-NMR spectra of (1) and (2) in C6D6 show multiplets at
~ = 5 . 2 5 ( 2 H ) 8.6(2H),
,
and 10.06(2H), and at .c=5.73(2H), 9.0(2H),
and 10.35 (2 H), respectively.-M.
L. Maddox, S. L. Stafford, and
H . D. Kaesz, Advan. Organometal. Chem. 3, 1 (1965), give an analysis
of the coupling constants for (11.
[7] C . Kruger and Yi-H. B a y , Angew. Chem. 83, 250 (1971); Angew.
Chem. internat. Edit. 10, 261 (1971).
[8] 0. S. Mills and G . Robinson, Proc. Chem. Sac. (London) 1960,421.
[9] The 'H-NMR spectra of 1,3-~yclohexadienetricarbonylironand
(3) in C6D, show multiplets at ~ ~ 5(2H),
. 3 7.2 (2H), and 8.6(4H),
and at T = 5.66 (2 H), 7.46 (2 H), 8.05 (2 H), and 8.95 (2 H), respectively.
-R.Burton, L.Prart, and G . Wlkinson, J. Chem. SOC.1961, 594, give an
analysis of the coupling constants of the tricarbonyl complex.
[lo] The 'H-NMR spectra of isoprenetricarbonyliron and ( 4 ) in
C,D6 show multiplets (m) and singlets (s) at r=5.1 (1 H ; m), 8.17
(3H;s), 8.53(2H;m), and 10.1(2H;m), and at ~ = 6 . 1 ( 1 H ; m ) 8.32
,
(3 H ;s), 8.93 (2 H ; m), and 10.4 (2 H ;m) respectively.
[ll] P. Heimbach, P . W Jolly, and G . W l k e , Advan. Organometal.
Chem. 8, 29 (1970).
[12] A detailed discussion will appear elsewhere
Molecular and Crystal Structure
of Bis(1,3-cyclohexadiene)monocarbonyliron
By Curl Kriiger and Yi-Hung Tsuy"]
Bis(l,3-cyclohexadiene)monocarbonyliron ( I ) ['I, a compound of interest because it is isosteric with starting
materials employed in the production of highly active
nickel catalysts, crystallizes in the orthorhombic space
[*I
Dr. Carl Kriiger and Dr. Yi-Hung Tsay
Max-Planck-Institut fur Kohlenforschung
433 Miilheim-Ruhr, Lembkestrasse 5 (Germany)
Angew. Chem. internat. Edit. / Vol. I0 (1971) / No. 4
Fig. 1 (above) and 2 (below). Maximum estimated errors: lengths
- 0.006
; angles 0.5".
+
A
The two rings differ in conformation and in their bonding
to the iron by amounts that are too large to be accounted
for by experimental errors. This may be due to slight
predominance of the limiting structureA in ring 1(Cl-C6),
and structure B in ring 2 (C7-C 12). Both kinds of bonding
have been considered for analogous diene complexes[31.
However, the observed distortions could only be induced
26 1
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