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Facile Synthesis of Pentaphenylnickelocene and Other Pentaphenylcyclopentadienylnickel and -cobalt Complexes.

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[I] R. Appel. W. Schuhn, F. Knoch, Angew. Chem. 97 (1985) 421; Angew.
Chem I n r . Ed. Engl 24 (1985) 420.
121 For example, F. A. Cotton, C . Wilkinson: Anorganische Chemie. 4th ed.,
Verlag Chemie, Weinheim 1982, p. 133; Advanced Inorganic Chemistry.
4th ed., Wiley-lnterscience, New York 1980, p. 131.
131 Experimental procedure: 3 : 1 (1.197 g, 4.18 mmol) [ I I] and 2 (1.165 g,
4.18 mmol) [I21 in 20 m L of toluene were stirred at 90°C for ca. 3.5 h.
After removal of all volatiles, the product was dried for several hours in
an oil-pump vacuum. 3 separated out quantitatively as a pure (NMR)
red oil, which could not be induced to crystallize ( N M R and IR data
141). 5 - 3 (1.901 g, 4.18 mmoi) and 4 (1.698g, 4.18 mmol) were refluxed
in 30 m L of xylene for ca. 15 h (end of reaction determined by 'HNMR). After removal of all volatiles, the product was dried for several
hours in a n oil-pump vacuum. The yellow, parlially viscous residue was
dissolved in cd. 30 mL of toluene, filtered through filter flocks and
cooled for 1 d at 0 ° C and again at -35°C After the toluene had been
decanted, the yellow crystals were washed with ca. 3 m L of cold toluene
and dried in vacuum (10 torr). Yield: 1.28 g (46Oh).
[4] "P{'HI-NMR(81.0 MHz, 20°C. GD,, 85% H3PO9ext.). During theconversion of 3 into 5 , a transient singlet appears at 6=234.9, which we
assign to the intermediate [Cp(CO),Mn+-P(NR,)(=NR) + Re(CO)aBr].
''C('HI-NMR (50.28 MHz, [D,]acetone, TMS int.) 3 (-60°C): 6=231.7
(d, CO, 'J(PC)=34.2 Hz), 85.8 ( s , CJHS),4.10, 3.63 (s, SiCH,). 5
( - 4 0 ' C ) : 8=232.9 (d, CO, Mn, 'J(PC)=19.8 Hz), 197.7, 191.7 (s, CO,
Re), 83.4 (s, C,H,), 1.6 (s, SiCH,). 'H-NMR(200 MHz. CjDg, TMS int.)
3(8O"C).ii=4.19(d,SH,'J(PH)=1.8Hz),0.32(~, lSH),O.21(s,9H).5
(20°C): 0'=4.08 (d, 5 H,'J(PH}= 1.5 Hz), 0.41 (s, I8H),IR: 3 (n-hexane)
v(CO)= 1970 (s), 1912 c m - ' ( s ) . 5 (C,H,): v(C0)=2020 (s), 1940 (sh),
1910 (vs, br), 1890 ( s , br), 1840 c m - ' (m, br).
[S] 5 : P2,2,2,,a=18.070(6),b=11.361(3),c=12.325(4)~,2=4,p,,,,~=1.87
g.cm '. 1417 observed of 1893 unique reflections (MoKn,f,i;:>-2.0cr(F&
2 f/5 45 '); R = 0.059, R, =0.053 Further details of the crystal structure
investigation are available on request from the Fachinformationszentrum tnergie, Physik, Mathematik GmbH, D-75 14 Eggenstein-Leopoldshafen 2. on quoting the depository number C S D 51 579, the names of the
authors. and the journal citation.
[6] a ) H. Lang, L. Zsolnai, G. Huttner, Angew. Chem. 95 (1983) 1016: Angens. Chem lnt. Ed. Engl. 22 (1983) 976: Angew. Chem Suppl. 1983.
1451: b) G. Huttner, H:D. Miiller, A. Frank, H.Lorenz, h i d . 8 7 (1975)
714 hrw. 14 (1975) 705.
[7] B. E. R. Schilling, R. Hoffmann, D. L. Lichtenberger, J . Am. Chem. Soc.
101 (1979) 585.
181 a) S. Pohl, J. Organomer. Chem. 142 (1977) 185,195; b) 0. J . Scherer, R.
Konrad, C. Kruger, Y:H. Tsay, Chem. Ber. 115 (1982) 411.
[9] R. Graziani, L. Toniolo, U. Casellato, R. Rossi, L. Magon, Inorg. Chim.
Acto 52 (1981) 119.
(101 S. Pohl, Chem. 5er. 112 (1979) 3159.
[I I ] G. Brauer: Handbuch der Prijparativen Anorganischen Chemie, Ed. 3,
Enke, Stuttgart 1981, p. 1887.
[I21 0. J. Scherer, N . Kuhn, Chem. Eer /07(1974) 2123.
Facile Synthesis of Pentaphenylnickelocene and
Other Pentaphenylcyclopentadienylnickeland -cobalt
Complexes**
By Wolfgang Klaui* and Ludwig Ramacher
Pentamethylcyclopentadienyl complexes have been extensively studied in recent years.''] They can be obtained
from halogeno-transition-metal complexes [ML,X,J and
alkali-metal-, Grignard- or thallium-cyclopentadienides.
Several reports show that the synthesis of transition-metalpentaphenylcyclopentadienyl complexes via this route is
The preparation of alkali-metal-pentaphenylcyclopentadienides is, however, not unproblematical.
When pentaphenylcyclopentadieneis allowed to react with
alkali metals, formation of the remarkably stable penta[*I
Prof. Dr W. KIiui, DiplLChem. L. Rdmacher
Institut fur Anorganische Chemie der Technischen Hochschule
Templergraben 55, D-5100Aachen (FRG)
1%") This work was supported by the Fonds der Chemischen lndustrie. We
thank Prof. Dr. H . Lueken for measuring the magnetic susceptibilities
and Mrs. S . Paul and Priv.-Doz. Dr. U . K d e for recording the cyclovoltammograms.
Angen. Chem. I n ! . Ed. Engl. 25 (1986) No. I
phenylcyclopentadienyl radical is frequently observed as a
side reaction. Furthermore, the secondary products of this
radical are often difficult to separate. We have therefore
searched for an alternative entry to perphenylated cyclopentadienyl-metal complexes.
Using the reaction of pentacarbonyliron with bromopentaphenylcyclopentadiene to give bromodicarbonyl(pentaphenylcyclopentadienyl)ironls]as starting point,
we found that the oxidative addition of bromopentaphenylcyclopentadiene is an elegant method for the preparation of pentaphenylcyclopentadienyl-nickel and -cobalt
complexes. C5PhSBris easier to obtain than CsPhSH and is
smoothly accessible in large amounts in analytically pure
form.[61 Reaction of stoichiometric amounts of CsPhSBr
and tetracarbonylnickel in tetrahydrofuran (TH F) leads to
the formation of di-p-bromobis(pentapheny1cyclopentadienylnickel) 1 in almost quantitative yield.
The chloro compound can be prepared in the same way.
1 is remarkably stable towards heat (no decomposition below 200°C), but is sensitive to air in solution. It is the second halogeno-bridged cyclopentadienylnickel compound
of this type so far reported. The corresponding pentamethylcyclopentadienyl compound, first synthesized by Ko11e
et al., is storable only below - 10°C."l The analogous unsubstituted cyclopentadienyl complex is not known. Depending upon the temperature, varying amounts of the carbony1 complex 2 are also found to be formed in addition
to the dimeric compound 1. The complex 2, which is
probably the primary product of the reaction, can be synthesized by reaction of 1 with CO at room temperature
and normal pressure in THF.IX1The method used for the
synthesis of 2 can also be used for the synthesis of 3Ix1
starting from C5PhsC1.161It is surprising that 2 and 3 are
the first stable compounds of type A that have become accessible. We have been able to prepare the iodo complex 4
for the first time by halide-exchange from 2 in acetone.[']
The carbonyl complexes 2, 3, and 4 are, like I , deep-red
crystalline compounds that are storable in presence of air
for weeks at room temperature but air-sensitive in solution.
They are of interest as starting substances for the synthesis
of sandwich complexes of the type B and C.1911 reacts
with thallium cyclopentadienide in T H F to give the previously unknown pentaphenylnickelocene 5.1'01
The air-sensitive, olive-green compound is, as expected,
paramagnetic in solution and in the solid state. The magnetic moment (dichloromethane, Evans method) is
perf=2.9 B.M. The magnetic moment of the solid was
found to be peff=3.2B.M. at 25°C.
[C,Ph,)Ni(CO)Br]
2
[(C,R,)Ni(CO)X]
A, X=CI, Br
[(C,Ph,)Ni(CO)CI]
3
[(C,Ph,)NiLX]
B
[(C5Ph5)NiL,]@
C
Pentaphenylnickelocene 5 can be reversibly oxidized at
+0.085 V and +0.98 V (SCE) in dichloromethane to the
mono- and dication, respectively (Fig. 1). The oxidation
potentials are shifted slightly compared to those of the unsubstituted nickelocene (-0.02 V, + -0.9 V under identical conditions). The markedly greater stability of the pen-
0 VCH Verlagsgesellschafi mhH. 0-6940 Weinheim, 1986
0570-0833/86/0101-0097 $ 02.50/0
91
taphenylnickelocinium dication compared to that of
[Ni(CsHs)z]2' is probably due to the sterically very bulky
pentaphenylcyclopentadienyl ring. By way of contrast
electronic effects are responsible for the stability of the
corresponding permethylated dication.'' 'I
A
I
10
05
- NI
oc
u
Fig. I . Cyclovoltammogram of 5 in CH&'12/[Bu,N]Pf-,+; Pt electrodes,
100 m V SKI
Reaction of CsPh5Br with octacarbonyldicobalt in T H F
led to a product mixture from which we were unable to
isolate any pentaphenylcyclopentadienyl complexes. However, we were able to synthesize dicarbonylpentaphenylcyclopentadienyl cobalt 6 in good yields by reaction of
CSPhjBr with K[CO(CO),].["~ This compound too is distinguished by its exceptional thermal stability compared to
that of the corresponding C,H,- and CsMej-compounds. It
is, e.g., sublimable in vacuo at 180°C. However, in the
solid state it is rather sensitive to oxidation. Preliminary
investigations have shown that 6 is suitable as starting
compound for the photochemical synthesis of cyclooctadiene(pentapheny1cyclopentadienyl)cobalt and probably
also for a series of analogous bis(olefin) complexes.
Five phenyl groups appear to stabilize cyclopentadienyl
complexes even more strongly than d o five methyl groups.
We have now found that the oxidative addition of halogenopentaphenylcyclopentadienes also constitutes a simple
strategy for the synthesis of C5Ph5complexes of 4d and 5d
metals.
Received: September 6, 1985 [Z 1454 IE]
German version: Angew. Chem. 98 (1986) I07
[ I ] See, e.g., P. T. Wolczanski, J. E. Bercaw, Ace. Chem. Res. 13 (1980) 121:
P. M. Maitlis, ibid. I 1 (1978) 301: R. B. King, Coord. Chem. Rev. 20
(1976) 155.
121 J. Powell, N . I. Dowling, Organomeralhcs 2 (1983) 1742.
(31 R. Zhang, M. Tsutsui, Youji Huaxue 1982, 435; Chem. Abstr. 98 (1983)
198374q.
[4] M. J. Heeg, C. Janiak, J. J. Zuckerman, J. Am. Chem. Soc. 106 (1984)
4259.
[5] S. McVey, P. L. Pauson, J . Chem. SOC.1965. 4312.
[6] We have prepared CSPhsBr and CsPh5Cl from tetracyclone on a 5 0 g
scale (see, e.g., A. K. Youssef, M. A. Ogliaruso, J . Org. Chem. 37 (1972)
2601. W. Broser, P. Siegle, H. Kurreck, Chem. Ber. I01 (1968) 69; K.
Ziegler, B. Schnell, Justus Liebigs Ann. Chem. 445 (1925) 266)
[7] U. Kolle, B. Fuss, F. Khouzami, J. Gersdorf, J. Organomef. Chem. 290
(1985) 77.
IS] Procedure. 1 : A solution of CrPhSBr(5.0 g, 9.5 mrnol) in anhydrous T H F
(30 mL) was treated with 1.25 rnL (9.6 mrnol) of Ni(CO),, and the mixture stirred for 24 h. The resulting reddish brown precipitate was filtered
off, washed with a small amount of THF, and then dried in a high vacuum. Yield 5.2g (90%). The product contained a small amount of 2
and was suitable in this form for further reactions.-2: Upon passage of
CO through a suspension of 1 in T H F at 25 "C a dark-red, clear solution
was obtained. The solvent was removed by bubbling with CO, and the
reddish brown product that separated was briefly dried in vacuo. 1R
(KBr): 2047 crn-' (v(CO)).-l, CI instead of Br: C,Ph5CI (I.Og, 2.1
mmol) and Ni(CO), (0.27 mL, 2.1 mmol) in T H F ( I 0 rnL), 50°C. analogously to the preparation of 1. Yield 0.99 g (SSo/o),correct C,H analysis.-3. By gassing a suspension of 1, CI instead of Br, with C O as de-
98
0 VCH Verlagsgeselischafi mbH. 0-6940 Weinheim. 1986
scribed for 2. IR (KBr): 2052 c m - ' (v(C0)).-4: A suspension of 2
(200 mg, 0.33 mmol) in acetone was treated with excess Nal. After 5 h
the solvent was removed by distillation and the residue was taken up in
dichloromethane; undissolved NaI and NaBr were removed by filtration, and the filtrate evaporated to dryness. Yield: 180 mg (83Oh). 1R
(KBr): 2039 cm - ' (v(C0)). The mass spectrometrically controlled bromideliodide exchange went to completion.
191 Complexes of type B are formed upon reaction of 1 with stoichiometric
amounts of L, e.g. tertiary phosphltes, at room temperature in dichloromethane. Purification by column chromatography on silica gel; yield ca.
70%. Cationic complexes C are formed upon reaction of 1 with an excess of L in the presence of TIBF, in dichloromethane. Purification o n a
silica gel column with acetone. Yield ca. 80%
[lo] Procedure. 5 : A suspension of 1 (300 mg, 0.26 mmol) in freshly distilled
T H F (10 mL) was treated with 140 mg (0.52 mrnol) of thallium cyclopentadienide. After 2 h the green solution was filtered and evaporated to
dryness. Subsequent purification by chromatography on silica gel with
T H F (2 x ) under nitrogen followed by removal of the eluent by dlstillation afforded 260 rng (88"h) of 5 as an olwe-green microcrystalline
powder. Correct C.H analysis. MS (El, 70eV, 160°C) m / z 568 ( M a ,
IXNi).
[ I 11 U. Kolle, F. Khouzami, Angenz. Cbem. 92 (1980) 658: Angew. Chem. Int.
Ed. Engl. 19 (1980) 640.
1121 Procedure. 6 0 : A solution of K[Co(CO),] ( 0 6 9 g, 3.3 mmol) i n T H F
(50 mL) was treated with 1.72 g (3.3 mmol) of CiPh5Br and the mixture
stirred for 3 d at room temperature. The solvent was then removed by
distillation and the reddish-brown residue chromatographed at + 10°C
o n a silica gel column (eluent: first hexane, then etherldichloromethane
I : I). The dicarbonyl complex 6 was eluted as a purple solution, which,
after evaporation to dryness, furnished 1.50g (81°/u) of 6 as a reddish
brown, microcrystalline powder. The product is air-sensitive and can be
purified by sublimation at 180°C in vacuo. Correct C,H analysis. IR
(CH2CI,): 2010, 1952 c m - ' (v(C0)). MS ( E l , 70eV, 25°C) m/z 560
(Me).
Di- and Trifluoro-Substituted Dilithium Compounds
for Organic Syntheses**
By Dieter Seebach,* Albert K . Beck, and Philippe Renaud
Fluoroorganic compounds are of increasing interest,
mainly for the synthesis of biologically active products.[']
Fluoro substitution can cause problems in synthetic transformations, since fluoride can act as a leaving group.[*]
Thus, the b-fluoro-substituted nitroalkanes 1") d o not undergo base-catalyzed nitroaldol additions to carbonyl compounds:f41b-elimination is so strongly favored that reaction
of 1 with N,N-dimethyl(trimethylsilyl)carbarnate affords
fluorine-free nitroenamines 2. To our great surprise, the
dilithio derivatives 3 and 4 of the fluoronitroalkanes l a ,
la: R = H,X = F
lb: R
lc: R
=
=
X= H
Me, X = F
Za: R = H,X = NMe, (75%)
2b: R = X = H (62%)
2c: R = Me, X = NMez (67%)
l b could be generated with butyllithium, were of comparable stability (up to -70°C) to the nonfluorinated anal o g u e ~ , ' and
~ ] reacted with aldehydes and ketones to give
the adducts 6-9 (Table 1 ; for experimental procedure see
ref. 151). The adducts were formed in 50-60% yield but
[*I
Prof. Dr. D. Seebach, A. K. Beck, DipLChem. P. Renaud
Ldboratorium fur Organische Chemie der
Eidgenossischen Technischen Hochschule
ETH-Zentrum, Universitatstrasse 16, CH-8092 Zurich (Switzerland)
[**I Partially from the projected Ph. D. thesis of P. R.-The
ethanes were supplied by Bayer AG, Leverkusen.
0570-0833/86/0101-0098 $ 02.50/0
fluoronitro
Angew. Chem. Int. Ed. Engl. 25 (1986) No. I
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pentaphenylnickelocene, synthesis, pentaphenylcyclopentadienylnickel, complexes, faciles, cobalt, othet
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