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Tetrakis(ethylene)irondilithium and Bis(4-1 5-cy-clooctadiene)irondilithium.

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fin complexes is based upon the reaction of metallocenes
with alkali metals in the presence of olefins. Starting from
ferrocene the first alkali metal-olefin complexes of iron could
be prepared["'.*I, which in turn are suitable precursors for the
synthesis of numerous novel organoiron compounds[2i.
Reaction of ferrocene at low temperature (-60 to
- 40 "C) in dimethoxyethane (DME) or tetrahydrofuran
(THF) with lithium sand and 1,5-cyclooctadiene (COD) or
ethylene leads, via exchange of only one CsH,-ligand, to formation of the hitherto unknown iron complexes
C,H,Fe(COD)Li(DME) ( l a ) or, after addition of N,N,N',N'tetramethylethylenediamine (TMEDA), to crystalline
C5H7Fe(COD)Li(TMEDA)(lb) or C5H5Fe(C2H4)2Li(TMEDA) (2) in high yields (ca. 80%).
CiH,Fe(COD)Li + C5H5Li
(1)
The "C-NMR spectrumI3l of (Ib) in [D,]toluene at -60 to
- 2 0 ° C shows besides the TMEDA signals (6=56, t: 46. q )
and the CsH,-signal(6 = 75.5, d) also two signals each for the
olefinic C-atoms (6=52.5 and 41.6, both d) and methylene
C-atoms (6=35.5 and 32.9, both t ) of the COD ligand; at
+ 80 "C only one resonance is observed for each of the two
groups of signals, namely at 6=47.9 (d) and 34.1 (t). As in
the case of the other alkali metal-transition metal-olefin
complexes, e. g. (COD),CoLi(THF)2r'h1, we ascribe this
equilibration of the COD signals to the increasing mobility
of the cationic Li-atom bound to the anionic C5H,Fe(COD)
core in the ion pair (16) with increasing temperature. In the
more strongly solvating THF, ( l b ) shows a relatively high
equivalent conductivity of A=8.7 cmz/R.mol (0.25 M at
- 30 "C).
The 7r-bonded olefin ligands in (1) and (2) are quantitatively replaced by carbon monoxide ( 1 atm) even at - 78 "C:
C5H5Fe(C0)2Li (3) is obtained [isolated as crystalline
C,H5Fe(C0)2Li(TMEDA)].The corresponding sodium compound C9H5Fe(C0)2Na is already well-known in solution141.
The complexes (1) and (2) can be used as precursors for
preparation of the hitherto unknown polynuclear complexes
(4), (S), and (6) having olefin ligands bound to iron atoms.
They are obtained from ( I ) and (2) and metal halides such as
ZnClz or CdC12.
The iron(1) compound (7), which is stable for several hours at
room temperature, exhibits a wide range of interesting reactions; its structure, like that of (2) and (5), was elucidated by
X-ray crystallography[".
Procedure
Ferrocene (50.0 g. 269 mmol) is stirred in T H F (350 ml)
and COD (100 ml) with Li-sand (5.2 g, 755 mmol) for 5-6 h
at - 50 "C. The reaction mixture is then allowed to warm to
room temperature, filtered free of excess lithium, and the filtrate concentrated to 250 ml by evaporation in cucuo. Addition of ether (600 ml) and TMEDA (150 mi) leads to precipitation of crystalline ( l b ) (71.2 g, 75%).
Received: March 1. 1979 [Z 249a I€]
German version: Angew. Chem. Y I . 590 (1979)
CAS Registry number\:
(Iu). 69393-65-3: ( / h / , 69393-63-1: /2). 70713-55-2: (3). 33361-37-4. (4). 707135h-3: (5). 70713-57-4: Ih). 70713-59.6. f,?). 70713-60-9, tC,H,)2Fe. 102~54-5
[I] a ) K. J u n m DOS 272411 I (197X). Studiengesellschaft Kohle mhH: h ) K.
Junar. R. M i n u i f . C. Kruger. J . C. Stkutu*:ki. Y: H. Tsrni~.Angew. Chem. 8 X .
XOX (1976): Angew. Chem. Int. Ed. Engl. I S . 767 (1976).
121 L. Schrefersrein. Dissertation. Universitat Bochum 1978.
[3] We thank Dr. R. iW.vnofi for recording and interpreting the "C-NMR spectra
(25.2 MHz. shifts rel. to TMS. multiplicities determined by off-resonance or
gated decoupling)
[4) a ) E. 0.F/.scher. R Borfrher. Z . Naturlorsch. B 10. 600 (1955). b) T. S Piper.
G. Wdkmson. J . Inorg. Nucl. Chern. 3. 104 (1956).
151 F. A Cuffon. G Wi/kin.wn. Z. Naturfbrsch. B 9. 453 (1954): 0.S. Mi//r, Acta
Cryrtallogr. I /. 620 (1958): R . D. fircher. A . Vogler. K Noack. J. Organomet.
Chem. 7. 135 (1967).
(61 C. Kruger er ui.. unpublished work.
Tetrakis(ethy1ene)irondilithium
c1ooctadiene)irondilithium
and
Bis(q4-1,5-cy-
By Klaus Jonas, Ludwig Schieferstein, Curl Kriiger, and YiHung Tsay['I
Recently we reported the alkali metal-transition metalethylene complexes (C2H4),NiLi2['I and (CLH4)4C~K[Za.31.
We have now been able to synthesize the isoelectronic iron
compound (C2H4)4FeLi2(2a.41.
As in the case of the more electron-rich m e t a l l ~ c e n e s it~ ~was
l possible to replace systemati+ ZnClz
cally both CSH5-ligandsin ferrocene uia a similar route.
2 C5H5Fe(COD)Li
[C5H5Fe(COD)]2Zn
- 2 LiCl
Reaction of ferrocene in tetrahydrofuran (THF) or dimethoxyethane (DME) at room temperature under slightly increased ethylene pressure ( = 5 atm) with an excess of lithium
+ 2 C4H6
-2COD
sand and subsequent addition of a mixture of diethyl ether
c
II
+ 2 L i TMEDA
and N,N,N',N'-tetramethylethylenediamine(TMEDA) to
2 C 5 H S F e C 4 H 6 L i ( T M E D A )A [ C S H ~ F ~ C , H B ] ~ Z ~
the filtered reaction solution leads on cooling (-30°C) to
- zn
crystallization of the yellow-green colored complex
(6)
(5)
(C2H4)4FeLi2(TMEDA)2
(1) (45% yield).
Replacement of the cyclooctadiene in the zinc derivative
Li, C z b
(C2H4)4FeLi, + 2 C5H5Li
(4) by butadiene leads to the trinuclear complex (S), which
(C5H5)zFe
THForDME:ZO"C
*
can be converted by reaction with lithium into (6) and metalTMEDA, E t a 0
lic zinc. Under mild reaction conditions (6) cannot be obtained directly from (1) and butadiene. Reaction of (1) with
( C , H I ) ~ FeLi,(TMEDA),
trityl chloride affords +q5-cyclopentadienyl(q4-1
,5-cyclooctadiene)iron (7) in high yields (70%), which, in contrast to the
ill
dimeric [C,HsFe(C0)2]114".'1.is obtained as the monomer
with an unpaired electron.
['I Dr K Jonas. Dr L Schiefersteln. Priv.-Do7 Dr. C Kruger [**I. Dr. Y -H.
Tsa) [**I
-
I
I
Max-Planck-lnstitut fur Kohlenfonchung
Kaiser-Wilhelm-Platz 1. D-4330 Mulheim-Ruhr (Germany)
["I
5 50
0 Yer/ag Chemie. GmhH. 69411 Weinherm. I 9 7 9
X-ray structure analysis.
057O-fJ~~y1
1/7Y/O707-0155(1 $ 02 5 0 / 0
Angen. Chem. I n f . Ed. Encl. I N ( l Y 7 Y ) No. 7
( I ) reacts with acetic acid and ethylenebis(dipheny1phosphane) (diphos) to give C2H4Fe(diphos)2[51
according to:
(I)
+ Zdiphos + 2CH3COOH
+
C2H4Fe(diphos)? +
2CzH4 + C,H,, + ZCH,COOLi
In the presence of stoichiometric amounts of alcohol or
ZnCl,, (1) exhibits the well-known activity of iron(o) catalysts'"' towards butadiene.
At - 78 "C, (1) reacts with carbon monoxide (1 atm) with
uptake of four equivalents of C O and liberation of four equivalents of C4H4. Reaction of ( I ) with 1,5-cyclooctadiene
(COD) at 40-70 " C affords (COD)2FeLi2 [isolated as crystalline (2a) or (Zb)],
(1)
+
2 COD
40-70 "c
[ I ] K . Jonu.\. Angew. Chem. X7. 809 (1975): Angew. Chem. Int Ed. Engl. 14. 752
(1975); K R. Pimchke. Dissertation. UniversitPt Bochum 1975
[2] a ) K . Jonus. DOS 2724 I I I (1978). Studiengesellschaft Kohle mhH: b) K.
Jonus. R. M ~ n u r i C.
. Kruger, J. C. Selrrlow.\ki. Y:H. Tsus. Angew Chem. &'i.
XOX (1976): Angew. Chem. Int. Ed. Engl. 15. 767 (lY76).
[ 3 ] E Deffinse. K. Junus. unpubliched work.
141 L. Schreferslein. Dissertation. Universitit Bochum 1978.
[ 5 ] G Hula. H . Kondo. A M l w k e , J . Am. Chem. Soc. 90. 227X ( I Y 6 X ) .
[6] M. Hidui. Y. Uchrdu. A. Mirono. Bull. Chem. Soc. Jpn 38. 1243 (196.5): A .
Curbonuro. A. Grew. G. DuN'A.sru. Tetrahedron Lett. 1467. 2037.
171 B. Bogdunoiii. M. Kroner. 6'. Wrlke, Justus Liebigs A n n . Chem 609. I
(1966).
[ X I Crystal data: u = 12.279(1). h = IS.M4(1). c.=l6336(2) (all value, i n 10 "I
m). space group Pbcn. Z = 4 . 2965 reflections ( Mo K ,.)with 1477 counted a h
unobserved (20). R=0.07X.
191 N. RBsch. R. Hoflmunn. Inorg. Chem. I.?. 2656 (1974).
(COD)zFeLiz + 4 CzH4
Structure and Reactivity of the Orthocarbonic and
Orthosilicic Acid Esters of Pyrocatechol
(COD),FeLi, (DME)z
(COD)zFeLi2(TMEDA ) Z
12ai
(2b)
thus completing the series of isoelectronic transition metalcyclooctadiene complexes of the 3 d elements of subgroup
8-namely
(COD),Ni"],
(COD),CoLi[']
and
(COD),COK''"-~', (COD)2FeLi,.
The X-ray structure analysislxl of ( I ) shows the central Fe
atom in a distorted octahedral environment with four equatorial C2H4 ligands and two Li atoms in the apical positions.
The iron-olefin moiety has approximately the geometry expected for d"' systems with ethylene ligands'''. A twofold
crystallographic axis runs through the iron atom and bisects
the C1 C1' vector. Short Li C bond lengths (Li C2:
2.174, Li C3': 2.215 A), as in (COD)2CoLi(THF)212h1,
indicate strong iron-pair interactions between the tetrahedrally
surrounded Li atom and the olefin C-atoms. The Li Fe distances are 2.619 A.
By Heinrich Meyer and Giinter Nagorsen"'
The observation that glassy bis(o-pheny1enedioxy)silane
(1) and other ring-strained orthosilicic acid esters are capable
of being polymerized even in the solid state"' urged us to investigate the structure of (1) and the corresponding derivative of orthocarbonic acid, 2,2-spirobi-1,3-benzodioxole
(2).
Zuckermunl2] believed that he had prepared monomeric
(1); however, the product obtained by him could very well
have been a mixture of oligomers. Polymeric ( I ) is readily
obtained by the following reaction:
2ChH4(0H)L+ Sic14
---t
l/x[(C,H402),Si],
+ 4HC1
Complete depolymerization takes place on transition into
the gas phase-no signals were observed above the molecular peak rn/e=244 in the mass spectrum. From the gas phase.
we were able to grow clear and colorless single crystals o f
monomeric ( I ) which are ver! hcnbitive to moisture and have
cs
C
C4
Fig. I . Structure of (C2H,),FeLi2(TMEDA)? 11) in the crystal: bond lengths in A
The method of reductive C5Hs-detachment by means of
alkali metal can also be used in the case of other q5-cyclopentadienyl-transition metal compounds. It has also proved
to be a useful method in the case of complexing agents other
than olefins-e. g., with phosphanes or molecular nitrogen.
Received: March I . 1979 [ Z 249b IE]
German version. Angew. Chem. 91. 590 (1979)
Angcu. ('hum. I u l . Ed. EngI. I8 ( I V 7 Y ) No. 7
a sharp melting point of 116 "C. We obtained monomericbut X-ray crystallographically amorphous-(1) by a procedure resembling that described by Allcock et al.['I.
[*] Dr. H. Meyer, Dr. G. Nagorsen
Institut fur Anorganische Chemie der Universitat
Meiserstrasse 1, D-8000 Miinchen 2 (Germany)
0 Verlug Chemre. GmhH. 6940 Wernhuim. 1 Y 7 Y
0.i 7 00h't.l.i
~ / T / f71)
J7.05.i 1 6 02.CO/ 0
551
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irondilithium, clooctadiene, ethylene, bis, tetrakis
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