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X-Ray Structure Analysis of the Triple-Decker Sandwich Complex Tris(-cyclopentadienyl)dinickel Tetrafluoroborate.

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= 1275 sh,
1248 vs both 6,CH3; 1018 m v,P=N; 945 s, br
v,,NSi,; 9.15 v P N ; a 8 6 5 sh, 838 vs, -830 sh all p,,CH3;
772 m, 756 m both psCH3; 685 m, ~ 6 7 sh,
5 639 m, 610
m-w all vSiC. Comparison of v,,.,(P=N) with the value for
a “pure” P=N stretching vibration of 1210-1220cm-1[’21
suggests that contributions from the polar resonance structure
[(CH
e
e
2N-P[-NSi(CH
d3]1
must also be taken into consideration in descriptions of the
bonding in (2)[l31.
The chemistry of the phosphorane (2) is largely determined
by the considerable electrophilic character of the phosphorus.
Thus, e.g., alcohols undergo ready addition to form the corresponding monophosphazenes (3).
(2) + HOR
R
= CH,
+
PR
K2N-P=NSiR3
I
HNSiR,
(3)
(3): yield 70%. IR: v(P=N)=1335; v(P0-R)=1182;
v(P-OR), v,,(PNSi)=1092,1062 cm-’. 31P-NMR: 6 = -1.8
ppm, 33,p=11.8Hz.
Experimental:
(CH3)3SiN3( I 5 g, 0.13 mol) is added dropwise with stirring
to [(CH3)3Si]2NPNSi(CH3)3(14g, 0.05mol) at 40°C in a
lOOml two-neck flask fitted with a dropping funnel and a
reflux condenser; the reaction mixture evolves N2 and warms
up to about 50 C . After evolution of gas has ceased, stirring
is continued for 2 to 3 h and unreacted silyl azide then drawn
off. The solid residue is fractionated by molecular distillation
at IOO--120 C, the phosphorane distilling over at 95 C/O.I
t o n . Renewed distillation affords 12 g (65 %) of pure product.
[ I I] M. M. Crutr.bfirld, D. H . Dunyan, L . H . Li,rc,hrr, V Marh. and J . R.
Van Wazrr, Top. Phosphorus Chem. 5, 391 (1967): M. Brrmann. ibid. 7.
325 ( 1972).
[I21 W Wiegriibr and H . B m k , Chem. Ber. 101, 1414 (1968).
[ I 3 1 A crystal structure analysis
[4] G. Murk/, Angew. Chem. 78, 907 (1966): Angew. Chem. internat. Edit.
5 , 846 ( 1966).
[5] E . Nirckr and W Flick, Angew. Chem. 85, 5x6 (1973): Angew. Chem.
internat. Edit. 12, 585 (1973).
[6] L. Birkofrr, A. Rirtrr, and P. Richter, Angew. Chem. 74, 293 (1962):
Angew. Chem. internat. Edit. i, 267 (1962). N . Wihurq, F . Raschiq. and
R. Sirsrmunn, ihid. 74. 38X (1962); I . 335 (1962).
[7] Subject to a detailed examination. we consider the intermediate formation
ofa phosphorane-silyl azide t o be highly probable on the basis of spectroscopic
evidencc.
[X] W Wolfihrrgrr, H . H . Pichrl. and H. S~hmidhairr,2. Naturforsch. 246,
979 (1971): and further literature cited therein.
[9] 0. J . Sdwrrr, Angew. Chem. H I , X71 (1969); Angew. Chem. internat.
Edit 8. X61 (1969): cf. also 0. J . Schrrrr and R. ThaIa<.Lrr.Z. Naturforsch.
276, 1429 (1972) and [5]
[lo]
The noise decoupled PFT ”Si-NMR spectrum was measured on a
70”4 solution in C6F6.
Angew. Chum. inrrrnot. Edi!. 1 Vol. 13 (1974) I N o . 2
in progress
X-Ray Structure Analysis of the Triple-Decker
Sandwich Complex Tris(q-cyclopentadieny1)dinickel
Tetrafluoroborate
By Erich Duhler, Marcia Textor, Hans-Rudolf Oswald, and
Albrecht Sa/zer[’]
We have performed an X-ray structure analysis on the complex
[Ni2(C5H5)3]BF4 recently synthesized by Werncr and
Salzed‘. 21 in order to confirm the “triple-decker sandwich”
structure proposed on the basis of chemical properties and
NMR spectra.
The single crystals prepared from a solution in propionic
anhydride are orthorhombic: space group P212121;
U = 17.019(2),
h= 11.454(2), c=8.074(1)A;
dexp=1.66,
deal,= l.69gcm-3; 2 = 4 . A total of 1216 independent reflections (180 not observed, I C 3 cI; 2 8 C 4 5 ” ; 0/2 0 scan)
were recorded on a Picker FACS 1 diffractometer with
Mo,, radiation.
The positions of the Ni atoms could be determined from
Patterson syntheses. A series of consecutive least-squares
refinements and difference Fourier syntheses revealed the
positions of the C, B, and F atoms. It became apparent that
assumption of fixed geometry of the rings, particularly with
regard to twisting in the plane of the ring, led to an incomplete
description of the positions of the C atoms in the three crystallographically distinct cyclopentadienyl ligands (“cp rings”).
Received: October 2, 1973 [Z 955 IE]
German version: Angew. Chem. 86. 128 11974)
[I] R. F. Hudson. Structureand Mechanism in Organo-Phosphorus Chemistry. Acddcmic Press, New York 1965: A. J . Kirby and S. G. Warren: The
Organic Chemistry of Phosphorus. Elsevier, Amsterdam 1967. A . F. Grrrard
and N . K . Homer. J. Chem. Soc. BIY6K. 539: D. L. Miller and T lihenu,
J . Amer. Chem. SOC.91, 3050 (1969): E. Lindner, H. D. Eherr, K . Geihl,
and A. Hoag,Chem. Ber. 104. 3121 11971): D. C . Gorrnsrrin. J. Amer. Chem.
Soc. Y4, 2.523 11972).
[2] 7: c‘. Bruicr and S. Bmkocic: Bioorganic Mechanisms. Benjamin. New
York 1966.
[3] Experimental proofhas recently been obtained for the intermediate formation of a monomeric alkyl metaphosphate in the gaseous phase: F. H . Wesrheimer, personal communication.
is
0
Fig. I . Structure ofthe tris(q-cyclopentadieny1)dinickel cation, [NidCsHs),]
+.
This is probably due less to true thermal vibrations than
to characteristic disorder phenomena in the crystals. Refinement converged to a value of R =6.3 %.
The structure of the complex cation [Ni2(~p)3]+,as shown
in Figure 1, agrees essentially with the proposed triple-decker
sandwich structure”]. Neglecting the observed disorder with
regard to twisting in the ring plane, the cp ring atoms are
depicted in an idealized manner (most probable positions
from difference Fourier syntheses).
The average distances between the Ni atoms and the C atoms
of the two terminal cp rings are 2.09 and 2.08A, whereas
[“I
Prof.
Dr. H. R. Oswald, Dr. E. Dubler. Dr. M. Textor, and A. Salzer
Anorganisch-chemjsches Institut der Universitat
CH-8001 Zurich, Ramistrdsse 76 (Switzerland)
135
values of 2.13 and 2.16A were found for the average Ni-C
distances to the bridging cp ring; the distances from the Ni
atoms to the centers of the rings are found to be: outer
cp rings 1.745 and 1.711 A, inner cp ring 1.771 and 1.805A.
The findings that the metal -C distances to the two terminal
cp rings are shorter than to the bridging cp ring accords
well with the picture obtained from the substitution reactions
of the [Ni2(cp)3]+ ion with Lewis basesE3].
Received: October 3, 1973;
revised: October 12, 1973 [Z 956 IE]
German version: Angew. Chem. 86. 125 (1974)
[l] H . Werner and A. Safzrr, Synth. Inorg. Metal-org. Chem. 2, 239 (1972).
[2] A. Salzer and H . Werner, Angew. Chem. 84, 949 (1972): Angew. Chem.
internat. Edit. 1 1 , 930 (1972).
[3] A. Salzer and H. Werner, Synth. Inorg. Metal-org. Chem. 2 , 249 11972).
Simple Synthesis of BicycIo[3.2.2]nona-6,8dien-3-ones
from A r e n e s [ * * I
By H . M . R. H o f f a n n and A . E. hill^*^
Dedicated to Professor Heinrich Hellmann on the occasion of his
60th birthday
We have found a simple one-stage transformation of benzene
into bicyclo[3.2.2]nona-6,8-dien-3-one ( I ), which uses the
silver salt promoted reaction with 2-methoxyallyl bromide[‘’
and proceeds at room temperature. After work-up with
dilute acid one isolates I-phenyl-2-propanone and ( I ) ,
m. p. 56 “C, IR (CCI,) 1698 cm- NMR (CCI,)[zJ: 6 =6.2-6.4
(m, 4Ha), 3.1-3.4 (br m, 2Hb), 2.35 ppm (d, 4Hc, J z 4 H ~ ) [ ~ l .
Interestingly, bicyclo[3.2.2]nona-6,8-dien-3-ones are sensitive
to acid, which is liberated throughout the silver trifluoroacetate
induced reaction. In neat deuteriotrifluoroacetic acid the parent bicyclic ( I ) was cleanly transformed into phenylacetone
after 3 h at room temperature. While this cleavage will lower
the yields, it is clear that a range of new and interesting
bicyclics has now become readily accessible.
Bicyclo[3.2.2]nona-6,8-dien-3-one( 1 )
Benzene (40 ml) and 2-methoxyallyl bromidec6](5g, 33 mmol)
are diluted with isopentane (100ml) and mixed with Na2C03
(2g). The resulting suspension is stirred with a vibromixer
(lOOcps), while a mixture of silver trifluoroacetate (log,
46mmol) and N a 2 C 0 3 (4g) is added in small portions at
room temperature over a period of 9 h. The reaction mixture
is stirred for a further 16h in the dark and then worked
lOOml), evaporation
up by careful addition of nitric acid (10 YO,
of the bulk of isopentane, and extraction of the resulting
suspension with CHC13 (3 x IOOml). The combined organic
layer is washed with water, dried, and the solvent removed.
A yellow oil is obtained; preparative glc (carbowax 20M,
206°C) affords I-phenyl-2-propanone (0.89 g, 20%) as a
colorless oil and bicycle[ 3.2.2]-nona-6,8-dien-3-one( I )
(0.27 g, 6 % ; work-up by fractional distillation gave a yield of
11 %).
Received: October IS, 1973 [Z 960 IE]
German version: Angew. Chem. 86, 127 (1974)
[l] A. E. Hill, G.Greenwood, and H. M . R. Hofmann, J. Amer. Chem. SOC.95,
1338 (1973); see also H . M . R. Hofmonn, Angew. Chem. 85, 877 (1973);
Angew. Chem. internat. Edit. 12,918 (1973).
[2] We thank Dr. A. J . Baker for sending us the NMR spectrum of ( I ) ,
see A. J . Baker, A . M . Chalmers, U! W Flood, D. D. MacNicol, A. B. Pmrose,
and R. A. Raphael, Chem. Commun. 1970, 166.
[3] The mass spectrum is in agreement with the quoted structure.
[4] Yield after isolation by preparative gas-liquid chromatography.
[S] Some polyalkylbenzenes give a minor amount of substituted 1,4-cyclohexadiene on nitration in solvent acetic anhydride: A. Fischer and J . N .
Ramsay, J. C. S . Perkin I1 1973,237, and references therein; see also P. C. Myhre,
J. Amer. Chem. SOC. 94, 7921 (1972); J . H. Ridd: Studies on Structure and
Reactivity. Methuen, London 1966, p. 133.
[63 G.Greenwood and H. M . R. Hofmonn, J. Org. Chem. 37,611 (1972).
Synthesis of 2,6,10,14Pentadecanetetrone, a 6-Tetraketone (“Harries’ Tetraketone”)
The analogous reaction with p-xylene afforded p-xylylacetone
(0.54g, 10%) and the 6,8-dimethyl derivative ( 2 ) (0.19g,
3.5%)[41, IR (CCI4): 1695cm- l, NMR (CC14): 6 = 5.7-6.0
(complex d, 2Ha), 2.7-3.0 (br m, 2Hb), 2.28, 2.32 (4H‘), 1.80
(d, 6Hd, J = 1 . 4 H ~ ) ‘ ~ l As
.
a minor bicyclic isomer
[(2) : (3)=3.5: 11 the symmetric 1,Sdimethyl derivative ( 3 )
was isolated. NMR (CCI,): 6=5.92 (s, 4H”), 1.32 (s, 6Hb),
2.20 (s, 4H’)13’. Toluene reacted in similar fashion.
Since dihydroindanones as, e.g., ( 5 ) in the case of benzene,
are not formed under our conditions, we suggest that the
bicyclics described arise in a concerted cycloaddition rather
than stepwise via the conventional cyclohexadienyl cation
( 4 ) , the exclusive formation of which might have been expected
in the reaction of benzene with a carbenium ion or electrophile[’].
[*] Dr. H. M. R. Hoffmann and Dr. A. E. Hill
William Ramsay and Ralph Forster Laboratories
University College, London WC 1 H OAJ (England)
[**I We thank the Science Research Council for selective support in the
field of organometallic chemistry.
136
By Burchard Franck, Volker Scharf, and Marieiuise Schrameyer“]
After hydrolysis of 1706g of the ozonide of a caoutchouc
sample previously subjected to partial isomerization by addition of HCI and subsequent dehydrohalogenation, Harried’]
succeeded, in 1914, in isolating a 0.05 % yield of a tetraketone
C 1 5 H 2 4 0 4(m. p. 123°C) which he suspected to have the structure ( I )[’I. This “Harries’ tetraketone”, although of unproven
structure, permitted the dramatic disproof of the cyclic formula
of caoutchouc ( 2 ) in favor of a higher molecular formula[’].
Moreover, if the compound really is the 2,6,10,14-pentadecanetetrone (Z), it represents the highest known member in the
series of poly-6-carbonyl compounds whose importance as
synthetic and biosynthetic precursors[’- 1‘ arises from their
ability to undergo diverse intramolecular condensations. We
have now been able to prepare the highly reactive &-tetraketone
( I ) , to establish its identity with Harries’ tetraketone, and
to convert it into condensation products.
[*I
Prof. Dr. B. Franck, Dr. V. Scharf, and DipLChem. M. Schrameyer
Organisch-Chemisches Institut der Universitat
44 Miinster, OrlCans-Ring 23 (Germany)
Angew. Chem. internat. Edit. 1 Vol. 13 (1974) / No. 2
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structure, complex, decker, dinickel, tetrafluoroborat, triple, analysis, trish, sandwich, cyclopentadienyl, ray
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