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CAS Registry numbers:
l a , 56598-30-2; lb, 56598-33-5; lc, 56636-18-1 ; 3a, 35295-88-6; 3b, 10379496-3; 4, 24143-17-7; 5a, 96782-78-4; Sb, 96782-85-3; 6a, 102818-68-8; 6b.
102818-65-5; 7a, 103794-93-0; 7b, 731-40-8; 8, 103794-94-1; 9, 103794-95-2;
10, 74666-82-3; methacrylic anhydride, 760-93-0.
Fig. I . Chromatography of a) penflutiztde 5a o n Za-“Si”; b) N-demethylchlormezanone 6a on 2b-“Si”; c) thalidomide 7b on 2c-“Si”; d ) chlorthalidone 10 (see text). Flow rate [mL/min], eluent composition (n-hexanel
dioxane): a) 1.5, 53 :47; b) 1.0, 65:35; c) 1.0, 75125; d) 0.7, 55:45.
bents. However, apparently on account of nonspecific adsorption to the amide anchor groups that are additionally
present, these preparations separate more poorly than d o
2- ‘‘si,”
If LiChrosorbB Diol is esterified with acetic acid instead
of with methacrylic acid, then, as expected, no binding of
the polyamide occurs upon polymerization of l a in the
presence of this acetoxy-substituted silica gel. Similarly,
polymerization of l a in the absence of a cross-linking
agent affords a soluble polyamide that does not bind to
LiChrosorba Diol suspended in toluene solution upon
heating. Surprisingly, however, polymerization of monomers such as la in the presence of LiChrosorbm Diol or
silica gel itself (LiChrosorbm) results, via an unknown
mechanism, in anchoring of the polyamides (ca. 10 wt-Yo)
to silica gel. Possibly, monomers and radical initiator are
adsorbed by the silica gel.
Upon heating,
- polymerization
would then occur predominantly on the surface of the silica gel, whereby mechanical tangling of the growing polymer chain in the pores of the silica gel would result in anchoring. The polymer is not washed out by solvents such
as n-hexane, toluene, dioxane, or 2-propanol.
The adsorbent[91obtained by polymerization of l a in the
presence of the diol phase is also suitable for direct resolution of enantiomers by HPLC. The studies carried out so
far have shown that the separations obtained are at least as
good as those with methacrylate-anchored polymerizates.
For example, base-line separations have been achieved for
the diuretic chlorthalidone 10 (Fig. Id), the muscle relaxant chlormezanone 6b, and the diazepine lopirazepam 3b.
The silica-gel-bound polyacryl- and polymethacrylamides
of type 2-“Si” described here exhibit unchanged separation ability even after repeated use.
Received. April 25, 1986 [Z 1744 It?]
German version: Angew. Chem. 98 (1986) 808
Angeu. C‘hem. I n r . Ed. Engl. 25 (1986)
No. 9
[ I ] G. Blaschke, J. Maibaum, J . Chromatogr. 366 (1986) 331.
121 G. Blaschke, Angew. Chem. 92 (1980) 14; Angew. Chem. Inf. Ed. Engf. 19
(1980) 13.
[3] G. Blaschke, J. Lig. Chromatogr. 9 (1986) 341.
141 G. Blaschke, H. Markgraf, Chem. Ber 113 (1980) 2031.
[5] H. Kley, Disserfatron, Universitat Miinster 1984.
[6] G. Blaschke, J. Maibaum, J . Pharm. ScI. 74 (1985) 438.
171 Experimental procedure: Z-“Si”: A suspension of diol phase (2.50 g,
LiChrosorbm 5 pm, Merck, Darmstadt, C=6.64%, H = 1.59%) in 20 mL
of anhydrous dioxane was treated under a stream of nitrogen with a
solution of methacrylic anhydride (1.50 g) in 10 mL of anhydrous dioxane and with diisopropylethylamine (0.80 g) in 30 mL of anhydrous
dioxane. The resulting reaction mixture was stirred for 30 min at room
temperature (RT), allowed to stand for 24 h at RT, filtered under suction
through a G-4 glass-frit filtering crucible and finally washed with
100 m L of dioxane. After drying under high vacuum at RT, a snowwhite product was obtained ( C = 8.27%, H = 1.76%). A suspension consisting of 2.5 g of this silica-gel-bound methacrylate in 10 m L of anhydrous toluene was treated under NZ with a solution of 7.5 g of l a in
20 mL of toluene and a solution of 22 mg of azobis(isobutyron1trile) in
10 m L of toluene, and the resulting reaction mixrure was allowed to stir
for 15 min at 80°C. The polymerization was terminated by addition of a
solution of 200mg of 4-rerf-butylcatechol in lOmL of toluene. The
product mixture was filtered through a G-4 glass-frit filtering crucible
and then washed with toluene, dioxane, n-hexane, and 2-propanol. After
drying in vacuum, ca. 3.0 g of Za-“Si” was obtained as a white powder,
C=21.35%, H=3.I0%, N = 1.16%. 2b-“Si”and 2c-“Si” were synthesized
analogously from Ib and Ic, respectively. However, in these cases, the
polymerization took 30 instead of 15 min.
[8] Experimenfal procedure: The adsorbents Z-“Si,” as suspensions in
30 m L of 2-propano1, were poured into steel columns (250 x 4.0 mm) under 450-500 bar pressure. In each case, 3-15 Fg of the racemate in dioxane solution was chromatographed. The solvent flow was maintained at
0.5-2.0 mL/min, a pressure of 20-100 bar being required, depending on
both the eluents and the flow rate. The products were detected with a
photodetector at 254 nm.
191 Experimental procedure: A suspension of 2.5 g of LiChrosorb@ 100 Diol
5 pm, used without further modification, was heated under N, in a stirred solution of 7.5 g of l a and 22 mg of azobis(isobutyronitri1e) in
40 mL of anhydrous toluene [lo] at 80°C. The reaction was terminated
by addition of 200 mg of 4-ferf-butylcdtechol in 10 mL of toluene and
the products were washed as described in [7]. Approximately 2.8 g o f a
white powder was obtained ( C = 12.48°/0, H =2.06%, N =0.65‘!h). FT-IR:
G = 1680 (amide), 1732 (ester) cm-’. The silica gel contained approximately 10 wt-% polymerizate.
[lo] Note added in proof (June 17, 1986): If the less polar cyclohexane I S
used instead of toluene as solvent, only 0.75 g of la is required to obtain
the same loading of polymerizate.
Bis(q2-ethene)(q6-toluene)iron* *
By Ulrich Zenneck* and Walter Frank
Preparative cocondensation reactions of iron atoms with
arenes, carried out at liquid nitrogen temperatures, afford
mainly the ($‘-arene)(q4-arene)iron complexes 1 , which decompose above approximately - 60°C.r2.31Trapping reactions with ligands have made it possible to synthesize numerous stable complexes of the type [($‘-arene)FeL,].t41We
[*I Dr. U. Zenneck
Anorganisch-chemisches lnstitut der Universitat
Im Neuenheimer Feld 270, D-6900 Heidelberg I (FRG)
Dr. W. Frank (crystal structure analysis)
Anorganische Chemie, Universitat
D-6600 Saarbriicken (FRG)
[**I Reactive n Complexes of the Group V I I l Transition Metals, Part 2. This
work was supported by the Land Baden-Wiirttemberg (Project No. 31Complex Chemistry) and by BASF AG. Part 1 : [I].
0 VCH Verlagsgesell.~chafimbH, 0-6940 Weinheim. 1986
0570-0833/86/0909-0831 $ 02.50/0
83 1
have now exploited the pronounced lability of one of the
arene ligands of 1 to synthesize new, reactive arene-iron
complexes, which, in contrast to 1 , are easier to handle.
These complexes open up a convenient approach to the
study of the organic chemistry of iron(o).
We report here the synthesis and characterization of
bis(q2-ethene)(Th-toluene)iron 2. We reported earlier the
first evidence of complexes of this type.['] Bis(to1uene)iron
l a is synthesized in situ and allowed to react at -60°C
with ethylene;['] the title compound 2 is obtained as a solution in toluene. After addition of n-pentane, the substance undergoes partial crystallization at - 78°C. The
synthesis of 2 from iron takes only a few hours and affords
a high yield of product (57%).
Complex 2 decomposes in solution above -20°C and
its crystals burst at 0 ° C ; greater stability is observed at
- 78 "C under ethylene. The decomposition products are
the ligands and metallic iron. Complex 2 has been characterized by 'H-NMR spectroscopy and an X-ray structure
analysis. The NMR spectra of 2 are difficult to obtain, because the complex decomposes to form metallic iron under
vacuum and upon short contact with wall surfaces above
- 20°C;161
even traces of iron particles cause line-broadening of 100 Hz or greater. The 'H-NMR spectrum of 2 suggests that it is very similar to cyclopentadienylbis(ethene)~obalt'~'but considerably more reactive. Both
ethene ligands are rigidly bound on the NMR time scale at
- 50°C.
I n contrast to ($-arene)diolefin-iron
complexes, the
olefin ligands in 2 are readily exchanged. Complex 2 undergoes rapid reaction with phosphites, phosphanes, and
diolefins to give often good yields of complexes of the type
(q6-toluene)FeL2.181 The known complex ($-tolue r ~ e ) F e [ P ( o C H ~ )3I4'l
~ ] ~ is formed quantitatively, so that
this reaction is also suitable for the determination of yields
of 2 in solution.
Fig. I . Molecular structure of 2 in the crystal. Orthorhomblc, space group
P2,2,2,, a=811(2), b= 1038(2), c = 1148(2) pm at T = - 130°C. 2 = 4 ,
~ ( C U K , ) =120.4 cm -I, photometer data, 623 absorption-corrected unique reflections, 61 refined parameters, R=0.087. The solution of the structure
could not be achieved by direct methods and the usual heavy-atom methods,
but only after consideration of packing [13]. Selected distances [pm]: Fe-C2
215(2), Fe-C3 212(2), Fe-C4 211(2), Fe-C5 208(2), Fe-C6 211(2), Fe-C7
216(2), Fe-C8 207(2), Fe-C9 208(2), Fe-CIO 202(2), Fe-CII 212(2), C K 2
157(3), C-C(arene) 139(2) (averaged). Further details of the crystal structure
investigation may be obtained from the Fachinformationszentrum Energie,
Physik, Mathematik GmbH, D-7514 Eggenstein-Leopoldshafen2 (FRG), on
quoting the depository number CSD-51975, the names of the authors, and
the journal citation.
The crystal lattice of 2 is made up of discrete molecules
(point symmetry I (C,) (compare Fig. 1). The deviation
from the higher point symmetry m (Cs),which was found
for (t~luene)Fe(bpy)[~'l,the only ($-arene)FeL, complex
whose structure was investigated previously, is considerable. The methyl group of the toluene ligand is twisted by
about 30" from the symmetrical position relative to the
ethene ligands. These ligands are thus approximately parallel to the hypothetical lines joining C2 and C4 as well as
C5 and C7. Examination of the Fe-Ca,enc distances (cf.
caption to Fig. 1) clearly reveals, furthermore, that the aromatic ring is "placed crookedly" upon the iron atom. The
angle between the best planes of the ethene and arene ligands is 4".All the indicated deviations from the "symmetrical" molecular structure can be ascribed to packing effects on the basis of an analysis of the intermolecular distances. The bond lengths of 2 d o not exhibit unusual values (mean values [pm] for 2, [(C,H,),Fe]2e1"~ and
[(C2H,)Fe(CO),(PPh,)]l'Z1: C-Cethene: 141, 142, 140;
2 : 212, [(toluene)Fe-Ceihene:207, 207, 210; Fe-C,,,,,
2 PX3
CAS Registry numbers:
la, 103883-75-6; 2, 100190-46-3
Complex 2 catalyzes the cyclotrimerization of alkynes
such as 2-butyne or 3-hexyne above O"C, 4-8 moles of
hexaalkylbenzene being formed per mole of 2.
Crystal struciure analysis: Although the orange crystals
of 2 are stable under ethylene at -78"C, under nitrogen
surface decomposition begins above - 5 0 T , resulting in
the formation of thin layers of iron. The methods employed for the manipulation of the crystalline material
must therefore take this sensitivity into c o n ~ i d e r a t i o n'I. ~ ~ ~
The results of the X-ray structure analysis confirm the
composition of the compound inferred from its reactions.
Received: January 31, 1986;
revised: May 27, 1986 [Z 1649 IE]
German version: Angew. Chem. 98 (1986) 806
>X,P /F e\ PX,
0 VCH Verlagsgesell.schaft mbH. 0-6940 Weinheim. 1986
[ I ] U. Zenneck, L. Suber. H. Pritzkow, W. Siebert, Chem. Ber. 119 (1986)
121 P. L. Timms, Chem. Commun. 1969. 1033.
131 S. F. Parker, C. H. F. Peden, J. Organomef. Chem. 272 (1984) 41 1 ; G . A.
Ozin, C. G. Francis, H. X. Huber, M. Andrews, L. Nazar, J . Am. Chem.
SOC. 103 (1981) 2453; P. D. Morand, C. G. Francis, Organomefallics 4
(1985) 1653.
[4] a) D. L. William-Smith, L. R. Wolf, P. S. Skell, J. Am. Chem. SOC. 94
(1972) 4042; b) R. Middleton, J. R. Hull, S. R. Simpson, C. H. Tomlinson, P. L. Timms, J . Chem. SOC.Dalton Trans. 1973. 120; c) S. D. Ittel,
C. A. Tolman, J. Organomef. Chem. 172 (1979) C41. 0rganometallic.s I
(1982) 1432; d) L. K. Beard, Jr., M. P. Silvon, P. S. Skell, J. Organomef.
Chem. 209 (1981) 245; e) L. J. Radonovich, M. W. Eyring, T. J. Groshens, K. J. Klabunde, J . Am. Chem. Soc. 104 (1982) 2816.
0570-0833/86/0909-0832 $ 0Z.S0/0
Anyew. Chem. I n ( . Ed. Engl. 2s (1986) No. 9
151 €vperrrn<m/ul procedure- la was synthesized from iron (5.5 g, 98 mmoi)
and toluene (300g) within 2 h by cocondensation at lo-' Pa and
- 196 C Ethylene (140 g, 5 mmol) was added to the mixture by condensation After the mixture had been stirred for 2 h at - 80 to -40°C and
then filtered at -30°C through A1,0J5"% H1O, an orange solution of 2
was obtained. The yield of 2 was determined to be 11.4 g ( 5 5 mmol,
57%). baaed o n Fe, by oxidative destruction of an aliquot (02,air or
acid) and titration with Titriplex 111. Addition of 300 mL ofn-pentane to
the solution of 2 resulted in the crystallization of approximately 1 g of
the complex in the form of orange parallelepipeds at -78"C.-'HN M R (300 MHz, [Dx]toluene, -50°C): 6=5.06 (br, 1 H), 4.28 (br, 2H),
4.12 (hr, 2H), 1.84 (5, 3 H ) (%-toluene); 1.91 ("d", 4H,,,,,,,,). 0.44 ("d",
AA'BB', J A H = 10.3 Hz (x-ethene).
[6] Sample preparation: A solution of 2 in [D8]toluenewas filtered through
a small amount of AI2O3/5% H1O at -50°C into an NMR tube. The
tube was then exposed to air for a short time until the solution adhering
to the walls of' the tube was oxidatively decomposed without noticeable
oxidation of the solution itself. Afterwards, the sample was frozen and
the tube sealed. Line widths of 5 Hz were attained if the sample was
transferred sufficiently fast to the spectrometer.
[7] K. Jonas, E. Deffense, D. Habermann, Angew. Chem. 95 (1983) 729; Angent Chem. In1 Ed. Engl. 22 (1983) 716: Angew. Chem. Suppl. 1983,
[XI U . Zenneck, H. Schaufele, A. Pfendert, unpublished results.
191 M. Veith, H Bsrninghausen, Acra Crysrallogr. 8 3 0 (1974) 1806.
[ I @ ] W. Frank, unpublished results.
1 1 I] K. Jonas, L. Schieferstein, C. Kriiger, Y.-H. Tsay, Angew. Chem. 91
(1979) 5Y0: Angew. Chem. I n / . Ed. Engl. 18 (1979) 550.
[ 121 E. Lindner, E. Schauss, W. Hiller, R. Faw, Angew. Chem. 96 (1984) 727;
Anyex Chem. In/. Ed. Engl 23 (1984) 711.
[ 131 A. J. Kirajgorodskij: Organic Chemical Cr~v.s/aflograph.v.Consultants
Bureau. New York 1959, p. 84-105.
I(C3Ph3)Ni(~-Br)3Ni(C3Ph3)KC3Ph3)A Triple-Decker-like Complex with
Triphenylcyclopropenyl as Ligand
By Franco Cecconi. Carlo A . Ghilardi, Stefuno MidoNini,*
Simonetta Moneti, and Annabella Orlundini
The cyclopropenylium system has recently attracted
considerable interest in organometallic chemistry because
it allows a variety of coordination types and reactions at
transition-metal centers."' The cyclopropenyl complexes
reported to date, however, contain strong donating ligands
such as CO, CSH5,PR,, and pyridine."' We now report the
synthesis and the structural characterization of an organometallic compound containing triphenylcyclopropenyl
as the only organic ligand.
In the course of repeated attempts to prepare the complex [Niz(C3Ph3)2BrZ],
previously reported in a patent,I3] by
the reaction of [ N i ( ~ o d )(COD
= 1,5-cyclooctadiene) with
C,Ph3Br in tetrahydrofuran (THF) solution, we succeeded
in isolating deep-red crystals of a compound having the
empirical formula Ni2(C,Ph,),Br3 l.I4]Complex 1 is only
formed if the molar ratio between the reactants is
[Ni(cod)J/C3Ph3Br 2 2/3.'*] The X-ray structure determination'" showed that 1 consists of [(C3Ph3)Ni(p-Br),3(C3Ph3)l0and C,Phy ions (Fig. I).
In the dimeric anion two eclipsed NiC,Ph, fragments
are linked together by three bridging Br atoms, which in
turn are staggered with respect to the six C atoms of the
$-coordinated cyclopropenyl ligands and lie on a plane
that is parallel to those of the cyclopropenyl rings. The Ni
atoms are thereby complexed in a double sandwich fash['I
Dr. S. Midollini. DipLChem. F. Cecconi, Dr. C. A. Ghilardi,
Dr. S. Moneti, Dr A. Orlandini
lstituto per la Studio della Stereochimica
ed Energetica dei Composti di Coordinatione, C N R
Via F. I>. Guerrazzi 27, 1-50 132 Florence (Italy)
Anqew. Chem.
Ed. Engl. 2 s (1986) No. 9
Fig. 1. ORTEP drawing (30'% probability ellipsoids) :'the crystal structure of
the complex anion of 1 . Selected bond distances [A] and angles ["I: Ni-Br
2.486(8)-2.514(7), Nil-Ni2 2.755(6), Ni-C l.85(4)-1.98(4), Ni I-Cent I 1.72(4),
Ni2-Cent2 1.75(4) (Cent1 and Cent2 are the points at the centers of the two
cyclopropenyl ligands); Brl-Nil-Br2 91.8(2), Brl-Ni I-Br3 92.1(2), Rr2-NilBr3 92.3(2), Brl-Nil-Cent1 125(l), BR-Nil-Cent1 124(1), Br3-NiI-Centl
122(1), Brl-Ni2-Br2 92.6(2), Brl-Ni2-Br3 93.0(2), Br2-Ni2-Br3 93.4(2), BrlNiZ-Cent2 122(1), Br2-Ni2-Cent2 125( I), Br3-Ni2-Cent2 1221I ) , NiI-Br-Ni2
ion between the cyclopropenyl rings and the three Br
atoms. If the cyclopropenyl ring is considered to occupy
one coordination site, then the Ni atoms are surrounded in
a distorted tetrahedral fashion by three Br atoms and the
cyclopropenyl ring, with angles around the nickel atoms of
91.8(2) to 125.4(10)". The two Ni polyhedra are essentially
similar, although corresponding bond distances and angles
show some small deviations. The six Ni-Br bond distances
range from 2.486(7) to 2.514(7) A and are therefore essentially equivalent. The triphenylcyclopropenyl ion does not
show any unusual features, displaying bond distances and
angles in agreement with those reported for free C3Phy.171
Complex 1 is not air stable and is practically insoluble
in THF, acetone and other polar organic solvents. It is
slightly soluble in CH2CIZ,undergoing irreversible decomposition to yield a green solution.
C P h Bi
3, 3
Scheme I
Complex 1 can also be prepared by reaction of
[(C,Ph,)Ni(CO)Br], with C3Ph,Br under a stream of Nz.
This reaction can be reversed by bubbling CO through the
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toluene, ethene, iron, bis
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