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Coordinatively Unsaturated Transition Metal-Substituted Cyclopropenylium Systems.

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dieny1)iron [FeI2 (1.7 g, 4.8 mmol) and 2 % Na amalgam (ca.
17g), was slowly added to a suspension of (1 c) (2.6g,
8.95mmol) in THF (10ml) cooled to -78°C. After warming
to -10°C the solvent was removed in a high vacuum, the
residue taken up in ether/dioxane 2 : 1 (15 ml), and the solution
quickely filtered, after cooling to - IO'C, through a G3 frit.
The filtrate was evaporated to dryness in high vacuum at
- 10°C, the residue taken up in ether (IOml), and the solution
stirred for several hours at -40 to -70°C. Cooling was
continued and the yellow crystals were freed from supernatant
liquor by means of an immersion frit, washed with ether,
ether/hexane 1 : 1, and hexane (5 ml of each, cooled at - 70"C),
anddriedinahighvacuum.Yield 1.51 g(46 %),m.p. 66-67°C
on rapid heating, decomposition.
Synthesis of ( 4 c ) , X=BF4: A solution of [Fe]-SiMe3[6J
(2.5 g, 10mmol) and (I e ) (3 g, 9.6 mmol) in chloroform (50 ml)
was refluxed for 1 h. After cooling to room temperature, the
volatile components were removed in a high vacuum. The
residue was taken up in CH2CI2 (15ml) and the resulting
solution filtered. Ether (20ml) was slowly added to the filtrate;
the precipitate was recrystallized from CH2C12/ether. Yield
1.75 g (40 %).
Received: February 7, 1978;
supplemented: April 13, 1978 [Z 961a IE]
German version: Angew. Chem. 90,490 (1978)
CAS Registry numbers:
( I a ) . 741-16-2; (1 b), 25339-22-4; ( I c ) , 37647-36-2; ( I d ) , 66633-50-9; (1 e ) ,
66633-48-5; ( I f ) , 66633-47-4; (1 9 ) . 32269-07-1 ; ( 1 h ) , 32269-08-2; ( 2 ) , 1215220-4; ( 3 a ) , 66652-60-6; ( 3 b ) , 66652-59-3; ( 3 c ) , 66652-73-1; ( 4 c ) (X=BF4),
66652-72-0; (4c)(X=C10a),66652-71-9; ( 4 c ) (X=Br), 66652-70-8; ( 4 c ) ( X =
SbCla),66652-69-5; ( 4 d ) (X=BF4), 66652-67-3; ( 4 9 ) (X=C104), 66719-18-4;
( 4 h ) (X =C104), 66687-75-0; ( 5 1 , 66652-65-1 ; ( 6 1 , 61695-57-6; [Fe]-SiMe3,
3181 1-63-9; [Fel-CI, 12107-04-9
R. Gompper, E . Bartmann, H. Noth, Chem. Ber., in press.
( 1 d ) was obtained from di-tert-butylcyclopropenoneand methyl fluorosulfate [very hygroscopic, 'H-NMR (CDC13): 6 = 1.47 (s, 18 H), 4.60
(s, 3H); IR (CH2C12): 1865, 1505 cm-'1.
M. L. H . Green, R . P. Hughes, J. Chem. SOC.Chem. Commun. 1975,
862.
a) K . Ofele, Angew. Chem. 80, 1032 (1968); Angew. Chem. Int. Ed.
Engl. 7 , 900 (1968); J. Organomet. Chem. 22, C 9 (1970); c) R. Weiss,
C . Priesner, Angew. Chem. 90, 491 (1978); Angew. Chem. Int. Ed. Engl.
17. 457 (1978); C . Priesner, Dissertation, Universitat Miinchen 1977.
C. W Rees, E. uon Angerer, J. Chem. SOC.Chem. Commun. 1972, 420.
7: S . Piper, D. Lemal, G . Wilkinson, Naturwissenschaften 43, 129 (1956).
a) Z. Yoshida,Abstr. 2nd Int. Symp. Chemistry of Nonbenzenoid Aromatic
Compounds, Lindau 1974. p. 23 (cf. [S]); b) the formulation as Li-cyclopropenylium salts originale< rrom R. Weiss, Habilitationsschrift, Universitat Miinchen 1976.
%. Yoshida. H . Konishi. S. Scmada, H . Ogoshi, J. Chem. SOC.Chem.
Commun. 1977, 850.
R . Weiss.personal communication (Dec. 21, 1977).
Coordinatively Unsaturated Transition Metal-Substituted Cyclopropenylium Systems[**]
By Robert Weiss and Claus Priesnerrl
We have examined the conditions under which coordinatively unsaturated transition metal-substituted species''] (1 )
can exist.
R
R
R
ML. =coordinatively unsaturated transition metal center
If the counterion Xe has ligand properties, it should be
incorporated into the coordination sphere of M to form an
electroneutral cyclopropenylidene complex (2). With the aid
of strong Lewis acids we have been able to transform compounds of type ( 2 ) into those of type ( 1 ) ; the substituents
R were found to exert a decisive influence.
We first synthesized complexes (4a)12]-(4 c ) which are
readily accessible in 60-70% yield from the dichlorides (3 )I3]
and Pd black according to
(a),R
=
14)
(c), R = N(i-C3H7)2
C6H5; ( b ) , R = t-C,H,;
The new carbene complexes ( 4 b ) and ( 4 c) (Table 1) are
orange-yellow, air-stable compounds showing considerable
thermal stability, which, unlike ( 4 a ) , are readily soluble in
polar solvents without pronounced donor character. Their
IR spectra have the same habit as that of ( 4 a ) in the region
of metal-halogen frequencied2l. The IR and 'H-NMR data
of ( 4 b ) and ( 4 c) are expectedly in accord with a large contribution from the resonance structure B.
Table 1. Characteristic data of the cyclopropenylidene complexes ( 4 b ) and
(4c).
-
M.p. P C ]
(46)
225
(dec.)
1R (KBr)
[cm-'1
'H-NMR
,i
1920 11111
13x0 ( > I
((
U V (C'HICI~)
Lax
[m] ( 8 )
1.37 I\)
IX'I.,. TMS)
1457 (s)
I396 (vs)
I383 (s)
(4c)
185
(dec.)
1855 (m)
1500 (vs)
1455 (s)
1400 (m)
1374Im)
-
4.0 (mc, 4H)
1.61/1.51 (d,
J=lOHz, 24H)
([D,-acetone,
TMS)
325 (4100)
Attempted abstraction of a C1- ion by a strong Lewis
acid from the palladium coordination sphere in complexes
( 4 a) and ( 4 c ) revealed a pronounced dependence upon substituent R. Thus the action of AgOS02CF3 on ( 4 a ) does not
release AgC1, whereas AgCl is released gradually in the case
of ( 4 b ) and instantaneously in the case of ( 4 c ) . No characteristic product of ( 4 b ) has been isolated; the desired reaction
does, however, take place with (4 c).
c
-
[*] Doz. Dr. R. Weiss ['I, Dr. C . Priesner
Institut fur Organische Chemie der Universitat Erlangen-Niirnberg
Henkestrasse 42, D-8520 Erlangen (Germany)
['I To whom correspondence should be addressed.
[**I Functional cyclo-C3 Derivatives, Part 6. This work was supported by
the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen lndustrie.-Part 5: [la].
Angew. Chem. I n t . Ed. Engl. 17 (1978) N o . 6
Compound ( 5 ) has so far only been isolated as amorphous
material [m.p. >118"C (dec.); IR (KBr): 1870 (s), 1525 (vs),
457
1444 (m), 1408 (m), 1380 (m), 1345 (s) cm-’; ‘H-NMR
(CD3CN)[’]:6=3.93 (mc, 4H); 1.52/1.42 (d, J=lOHz, 24H)l.
The ionic formulation of ( 5 ) follows from the characteristic
IR absorption bands of the anion at 1030, 1140, 1270 cm-’.
The fragment of highest mass number (m/e= 237) corresponds
to demetalation with formation of the cation (8).
The complexes ( 4 a ) - ( 4 c ) show a similar gradation of
reactivity towards SbC15. Thus ( 4 a ) does not react at all,
( 4 b ) only reluctantly and in still unknown manner, but ( 4 c )
combines instantaneously and quantitatively to give the hexachloroantimonate (6) corresponding to (5).
Compound (6) is a yellow, air-stable crystalline salt (m.p.
185°C (dec.)); its ‘H-NMR spectrum (CD3CN[’]) resembles
that of ( 5 ) . Apart from anion-induced differences, its IR spectrum is also similar to that of ( 5 ) . The presence of a discrete
SbCl; ion is evidenced by an intense IR band at 340cm-’
(10ml) is added and the salt (6) filtered off; yield 700mg
(94 %).
Received: March 6, 1978 [Z 961 b IE]
German version: Angew. Chem. 90,491 (1978)
Publication delayed at authors’ request
CAS Registry numbers:
( 3 ~ ) 2570-00-5;
,
( 3 b ) , 66633-01-0; ( 3 c ) , 66633-02-1; ( 4 ~ ) ,34390-60-8;
( 4 b ) , 66652-80-0; ( 4 c ) , 66446-50-2; ( S ) , 66652-79-7; (6), 66652-78-6;
( 7 ) , 66633-04-3; (S), 66633-06-5
p]
[2]
[3]
(V,,Y6I.
To our knowledge, (5) and (6) are the first coordinatively
unsaturated transition metal-substituted cyclopropenylium
systems[’! Such species are expected to undergo demetalating
SE reactions[’a1.We have been able to confirm this for two
model reactions: thus (6) can be subjected to electrophilic
chlorination by SbCI5, giving (7)f41, and to protonolysis by
conc. H2S04[’], giving (8)[41.
[4]
[5]
[6]
[7]
[8]
[9]
[l O]
[Ill
It seems logical to attempt to correlate the increasing tendency of palladium to release C1- in the series ( 4 a ) - ( 4 c )
with the donor properties of RL9]and thus with the increasing
weight of the polar resonance structure B. The ready formation
of ( 5 ) and (6) might possibly be rationalized by assuming
the three-membered ring in ( 5 ) and (6) to act as a four-electron donor according to the [3]radialene resonance structure[”] C. Hindered rotation of the NR2 substituent has not
yet been detected by ‘H-NMR spectroscopy, possibly owing
to the coordinating properties of the solvent CD3CN.
If the formulations ( 5 ) and (6) correctly represent the
structural situation, then the compounds are formally tricoordinate d8 complexes[“]. Such 14-electron systems play an
important role in homogeneous catalysis‘ ‘I.
a) R. Weiss, C . Priesner, H . WOK Angew. Chem. 90, 486 (1978); Angew.
Chem. In:. Ed. Engl. 17, 446 (1978); b) R . Weiss, C . Schlierf, K . Schloter,
J. Am. Chem. SOC.98,4668 (1 976).
K . ofel,, J. Organomet. Chem. 22, C 9 (1970).
The new dichlorides ( 3 b ) and ( 3 c ) were prepared by standard methods
from the parent cyclopropenones; see J. Ciabattoni, E. C. Nathan I l l ,
J. Am. Chem. SOC.90, 4495 (1968); Z. Yoshida, H. Konishi, Y. Tawara,
H.Ogoshi, ibid. 95, 3043 (1973); in contrast to ( 3 b ) , ( 3 c ) is a salt-like
compound [4].
C . Priesner, Dissertation, Universitat Munchen 1977.
CDJCN can he assumed to coordinatively saturate the Pd(1i) complex,
cf. also [2].
W Warrhmann, A. Schmidt, 2. Anorg. Allg. Chem. 418, 57 (1975).
After completion of our work [4], Gompper and Bartmann synthesized
some mono-[Fpl-substituted cyclopropenylium salts; [Fp] =
Fe(C0)2(q5-CsHS);R. Gompper. E. Burrniuiin, Angew. Chem. 90. 490
(1978); Angew. Chem. Int. Ed. Engl. 17,456 (1978).
No attempt was made to work under milder conditions.
Z. Yoshida, Top. Curr. Chem. 40, 47 (1973).
In hisdonor-monoacceptor-substituted cyclopropenium systems, the
[3]radialene character is generally very pronounced: R. Weiss, C .
Priesner, H . WOK M . Hertel, to be published.
Z Yared, S . L. Miles, R . Bau, C . A. Reed, J. Am. Chem. SOC. 99,
7076 (1978).
Double Deprotonation of 3-Nitropropene and 4-Nitro1-butene: Derivatives of Their Dianions as Novel Reagents for CC-Linkage
By Dieter Seebach, Rainer Henning, and Friedrich Lehrr]
To our knowledge, C-C linkage reactions with the allylic
nitronate (1) have not been reported in the literature; nucleophiles can add to the nitrobutadiene (2) in positions 2 or
4‘11.
Under the reaction conditions previously described by us
(2 equiv. of n-butyllithium at - 80 to -90°C in THF containing HMPT)[’I for generation of simple nitroalkane dianions,
N02Li2
(5)
/
-
’
Procedure
Synthesis of (6): A well stirred suspension of ( 3 c ) (612 mg,
2mmol) and pretreated[’] Pd black (212mg) in anhydrous
benzene (35ml) is refluxed for 2h. The new precipitate is
extracted with CH2C12and the carbene complex ( 4 c ) precipitated with ether; yield 520mg (63 %) of analytically pure
( 4 c ) . SbC15(297 mg, 1 mmol) in CH2C12(5ml) is added dropwiseat room temperature to a stirred solution of ( 4 c ) (411 mg,
0.5mmol) in CH2C12(5ml). A crystalline precipitate of (6)
is rapidly formed. After 20 minutes’ stirring, anhydrous CCI4
458
E
T
N
E
(7)
(8ai
O
z
-02
E
(86)
[*I Prof. Dr. D. Seebach, DipLChem. F. Lehr
Laboratorium fiir Organische Chemie der Eidgenossischen Technischen
Hochschule
Universitltsstrasse 16. CH-8092 Zurich (Switzerland)
Dr. R. Henning
Institut fiir Organische Chemie der Universitat
Heinrich-Bur-Ring 58, D-6300 Lahn-Giessen (Germany)
Angew. Chem. lnt. Ed. Engl. 17 (1978) No. 6
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metali, coordinatively, unsaturated, system, transitional, cyclopropenylium, substituted
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