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Decamercuration of Ruthenocene.

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tadiene (3), in which the diametrically opposite pairs of
double bonds have undergone [2 + 21 ring closure.
Reaction between syn-bisnorborneno-l,4-benzoquinone
(4)'"l and cyclobutadiene (liberated from its iron tricarbonyl
complex with ceric ammonium nitrate) furnished two [4+ 21
endo adducts 5"- 61 and 6 [ 561
. in a 55:45 ratio and 70% yield.
On irradiation with a Hanovia 450 W Hg lamp through a
Pyrex filter, 5 and 6 underwent smooth intramolecular
[zb + 7 4 ring closure to give nonacyclic, annulated bishomocubdne diones 7['. (61 O h ) and 8Is1 (35%), respectively. The bishomocubanone moiety in 7 was opened through
the reductive scission of cyclobutyl bonds conjugating the
1,4-dicdrbonyl functionality.[*] Thus, reaction of 7 with Zn
in acetic acid under ultrasonication furnished 915]and
(1 6: 1. 85 Yo).The octacyclic dione 9 in which one bond has
been cleaved could be transformed to heptacycle lof5]on
further exposure to Zn in ethanol in 30-40 YOyield. Alterna-
e"', Me&
NHZ-NH,. f
11, R = 0
1, R = H 2
Scheme I .
tively, 10 could be accessed directly from 7 in a single-pot
reaction with Zn in ethanol, albeit in somewhat lower yield
(about 25%). The reductive opening of the cage in 7
rendered the two double bonds proximal, and irradiation of
10 from a 450 W Hanovia lamp led to the desired intramolecular [2 + 21 cycloaddition, and the nonacyclic dione
1I I51 (40 Yo)was readily realized. Its structure was secured
through X-ray crystal structure determination.['] Deoxygenation of 11 presented considerable difficulties, but eventually a modified Wolff- Kishner reduction could be carried
out to furnish the C,,H,,-hydrocarbon, golcondane (1, 10~ O Y O ) ,which
' ~ ] as expected exhibited a 3-line I3C NMR spectrum (6 = 45.63, 41.04, 39.21), while 11 showed a 6-line I3C
NMR spectrum. The energy-minimized structure of I determined with MMX force-field calculations (Scheme 1, strain
energy = 132.4 kcalmol-I, AH; =74.9 kcalmol-') exhibited structural parameters closely resembling those for its precursor dione 11 obtained by X-ray studies.
The nonacyclic, annulated bishomocubanedione 8 on
zinc/acetic acid reduction also furnished the corresponding
heptacyclic dione 12 (50 YO)through reductive scission of two
C-C bonds. Several attempts at thermal [2 + 21 cycloreversion in 12 to furnish the novel head-to-head 1,4-cyclic tetramer 13 of 1,3-cyclopentadiene have not borne fruit so far
Angew. C'hrm. Int. Ed. Engi. 1993, 32. No. X
Scheme 2
(Scheme 2). Nonetheless, 10 and 12 are potential precursors
for 3 and 13, respectively, besides many other novel polycycles. These possibilities are currently being explored.
Received: January 26. 1993 [Z5830 IE]
German version: Angew. Chem. 1993, 108, 1230
[ l ] a) Cage H,ydrocarbons (Ed.: G. Olah), Wiley. New York, 1990: b) Curhocjclic Cage Compounds. Chemisrr.v and Applications (Eds.: E. Osawa, 0.
Yonemitsu), VCH Publishers, New York, 1992; c) N. Anand, T. S . Bindrd,
S. Ranganathan, Art in Organic Synthesu, 2nd ed., Wiley, New York. 1988.
(21 a) Review: L. A. Paquette, Chem. Rev. 1989, 85, 1051; b) review. W. D.
Fessner, H. Prinzbach in Organic Synthesis. Modern Trends (Ed.: 0.
Chizov), Blackwell, Oxford, 1987, p. 23; c) W. D. Fessner, G Sedelmeier,
P. R. Spurr, G. Rihs, H. Prinzbach, J. Am. Chem. Soc. 1987, f09,4626;
d) R. Gleiter, M. Karcher. Angew. Chem. 1988,100,851;Angew. Chem. Int.
Ed. Engl. 1988, 27, 840.
[3] In honor of the 400th anniversary of the founding of the city of Hyderabad,
in Southern India, we have named 1as golcondane, derived from Golconda.
the old name of Hyderabad; see the New Ox/ord Encyclopedic. Dictionur!,
Bay Books, Oxford University Press, Oxford, 1983, p. 720. IUPAC nomen1.09~'5.0'3~1q.014~'8]icoclature for 1: Nonacyclo[l0.7.1 .02~6.04~17.05~8.07~1
[4] a ) G . Mehta, S . Padma, S. R. Kana, K . R. Gopidas. D. R. Cyr. P. K. Das.
M. V. George, J Org. Chem. 1989,54, 1342; b) G. Mehta, S. H. K. Reddy.
Tetrahedron Lell. 1991, 32, 4989.
IS] All new compounds were characterized on the basis of 'H and "C NMR
spectra and analytical data (MS and/or elemental analysis). "C NMR data
in CDCI, for some key compounds: 1: I3C NMR (50MHz): 6 = 45.63,
41.04. 39.21; 5 : "C NMR (25.0 MHz): 6 =197.71, 170.60, 142.83. 140.18.
136.98, 73.88, 62.76, 49.29. 49.00, 48.47, 42.41; 6 : "C NMR (28.0 MHz).
6 =197.66, 171.00, 143.18, 138.06, 136.24. 72.65, 62.41, 50.89,
48.29; 7: 'T NMR (25.0 MHz). 6 = 213.07, 134.98, 68.71, 45.06, 43.83,
38.35; 8 : I3C NMR (28 MHz): 6 = 214.60, 136.88, 66.88. 49.82, 41.76.
37.41; 10: I3C NMR (28.0 MHz): 6 = 222.98, 134.41, 88.06, 41.88, 41.76.
38.17; 11: ',C NMR (25.0 MHz): 6 = 219.48. 84.06, 42.35, 41.94, 38.00,
161 The stereochemistry of 5 and 6 follows from the analyses of 'H NMR data
and chemical transformations. Further confirmation was obtained through
the X-ray crystal structure determination of an iirteresting photoproduct
derived from 5 ; see. G. Mehta, S. H. K. Reddy. V. Pattabhi, J. Chem. Soc.
Chem. Commun. 1992, 991.
[7] Besides 7, minor photoproduct(s) resulting from cleavage were also encountered during the photoirradiation.
[ X ] E. Wenkert, J. E. Yoder, J Org. Chem. 1970,35,2986; G . Mehta, K . S. Rao,
(bid. 1985, 50, 8837.
[9] The X-ray crystal structure of 11was kindly determined by Prof. V. Pattabhi, Department of Biophysics, Madras University, Madras, and will be
published elsewhere.
Decamercuration of Ruthenocene**
By Charles H . Winter,* Young-Hee Hun,
Robert L. Ostrander, and Arnold L. Rheingold
The mercuration of transition metal cyclopentddienyl
complexes has been largely limited to ferrocene and its
[*] Prof. Dr. C. H. Winter, Y:H. Han
Department of Chemistry, Wayne State University
Detroit, MI 48202 (USA)
Telepdx: Int. + (313)577-1377
Dr. R. L. Ostrander. Prof. Dr. A. L. Rheingold
Department of Chemistry, University of Delaware
Newark, DE 19716 (USA)
This work was supported by the Air Force Office of Scientific Research
(F49620-93-1-0072 to C.H.W.).
VCH Verlugsgesellschafr mbH. 0-65451 Wernheini, 1993
057o-OX33~93jOXo8-tl61$10.00+ .2S/O
derivatives, due to the electron-rich character and high stability of the bis(cyclopentadienyl)iron(n) framework.['] An
early study by Fischer et al. on the mercuration of
ruthenocene reported impure mono- and dimercurated complexes,[2a1 while Nesmeyanov et al. demonstrated that
ruthenocene could be monomercurated in low yield.[2b]Subsequent investigations have revealed that the reaction of
ruthenocene with Hg" salts often affords adducts with RuHg bonds, rather than electrophilic substitution
We recently reported that pentamethylruthenocene is preferentially pentamercurated at the unsubstituted cyclopentadienyl ligand with mercuric acetate.I4] However, extension of
mercuration reactions to other transition metal cyclopentadienyl complexes remains speculative due to the electronpoor nature of many complexes relative to ferrocene and
pentamethylruthenocene. Herein we report that ruthenocene
can be decamercurated in nearly quantitative yield and that
the permercurated ruthenocene can be directly halogenated
to efficiently afford decahaloruthenocenes. Permercuration
of the electron-deficient ruthenocene suggests that a wide
variety of permercurated cyclopentadienyl complexes may
be accessible. Subsequent derivatization should then provide
entry to a variety of new pentahalogenated cyclopentadienyl
Treatment of ruthenocene with mercuric acetate
(1 0 equiv) in refluxing dichloroethane for 18 h afforded deca(acetoxymercurio)ruthenocene (1) in 88 % yield as an offwhite solid which precipitated from the reaction medium
(Scheme 1). Complex 1 was rigorously insoluble in all common solvents, which prevented its analysis by NMR spectroscopy. The complex was, however, characterized by microanalysis and IR spectroscopy. In particular, the IR
spectrum of 1 revealed strong absorption bands characteristic of the HgO,CCH, functionality at 1570, 1403, 1382,
1337, and 643 cm-'. By comparison, mercuric acetate
showed strong absorption bands at 1555, 1400, 1330, and
653 cm-'.
KX3, HzO
3, X = BI
Scheme 1. Synthesis and reactions of 1. The complexes 1 and 2 were prepared
under reflux.
0 VCH Verlagsgesellschaf! mbH. 0-69451
Weinheim, 1993
Fig. 1. An ORTEP view of 3 with 35% probability ellipsoids. Selected bond
lengths [A] and angles ["I: Ru-C(1) 2.153(23), Ru-C(2) 2.193(18), Ru-C(3)
2.1 67(16), Ru-C(4) 2.1 61(20), Ru-C(S) 2.176(24), Ru-C(6) 2.163(1X), Ru-C(7)
2.168(20), Ru-C(8) 2.175(20), Ru-C(9) 2.169(19), Ru-C(1O) 2.172(19), RuCp(1) 1.80(2), Ru-Cp(2) 1.81(2); Cp(l)-R~-Cp(2)179.4(8).
which two eclipsed $-C,Br, ligands are $-bonded to the
ruthenium atom. The mean Ru-C bond lengths are 2.17 A
and the mean C-C and C-Br bond lengths 1.42 and 1.87 A,
respectively. The ruthenium-cyclopentadienyl centroid distances are 1.80(2) and 1.81(2) A, with a (C,Br,)-Ru-(C,Br,)'
angle of 179.4(8)". The ring-to-ring distance is 3.61 A; thus
the distance between the eclipsed interannular bromine substituents is shorter than the sum of their covalent radii
(3.84 A).['] The bromine substituents are bent slightly out of
the plane of the cyclopentadienyl ligands (range 1.7-6.4",
mean 4.2"), away from the ruthenium atom. Despite such
close Br-Br contacts, the molecule retains an eclipsed conformation. The structure of 3 is very similar to that previously reported for 2.'6b*81
The halogen substituents are ecli sed
in both 2 and 3, and the interannular distances (3, 3.61
3.598 A) and average Ru-C distances (3, 2.17 A; 2, 2.17 A)
are nearly identical. Moreover, the halogen atoms in 2 and 3
show small displacements out of the plane of the C, ring
away from the ruthenium atom. Unlike 3, the position of the
halogen atoms in 2 could not be attributed to interannular
interactions, since the CI-CI distances were larger than the
sum of their van der Waals radii.
Decamercuration of the relatively electron-poor ruthenocene ( E o = 1.03 V,191 compared to ferrocene (El,2=
0.31 Vt6']) and pentamethylruthenocene (E,,? = 0.54 Vr6"]))
suggests that a wide variety of other transition metal cyclopentadienyl complexes should undergo pentamercuration. In analogy with 1, ferrocene can be decamercurated
with mercuric acetate in refluxing dichloroethane to afford
deca(acetoxyrnercurio)ferrocene, which can be halogenated
The fully mercurated nature of 1 was confirmed by its
reaction with halogenating agents. Treatment of 1 with
CuCl, (50 equiv) in refluxing acetone for 12 h afforded
decachlororuthenocene (2) in 73% yield as a white crystalline solid after workup (Scheme 1). 'H NMR spectra of
the crude product 2 showed no signals that could be attributed to partially chlorinated ruthenocenes. Reaction of 1 with
KBr, and KI, (prepared from KX and X, in water where
X = Br or I) afforded decabromoruthenocene (3,47 %) and
decaiodoruthenocene (4, 39 %) as white and yellow-ochre
solids, respectively.
In order to gain insight into the bonding involved in the
decahalometallocenes, the X-ray crystal structure of 3 was
determined.[5.61Figure 1 shows a perspective view of 3, in
0570-0833/93/0808-11628 10.00f.25/0
Angew. Chem. Inf. Ed. Engl. 1993,32, No. 8
to afford decahaloferrocenes."O1Chlorination, bromination,
and iodination of 1 provides the complexes 2-4 in 39-73 YO
yields. Complex 2 was previously prepared in 14% yield by
repetitive lithiation/chlorination of ruthenocene."'' The
present synthesis of 2 from 1 is clearly superior.
In summary, pentamercurated cyclopentadienyl ligands
should not be viewed as exotic species, but rather as potentially accessible and useful synthetic intermediates.
Experimental Procedure
1 : A 250 mL round-bottomed flask was charged with Cp,Ru (0.231 g,
1.00 mmol), Hg(OAc), (3.187 g, 10.0 mmol), and dichloroethane (100 mL).
The mixture was refluxed for 18 h, during which time an off-white solid precipitated. The precipitate was collected on a medium glass frit and was washed with
hexane (40 mL). Vacuum drying afforded 1 as an off-white powder (2.492 g,
88 %). M.p. 200- 220 "C (decomposition range, with evolution of elemental
mercury); IR (KBr): F[cm"] =1570 (vs, C=O); correct C,H analysis.
2: A 250 mL round-bottomed flask was charged with 1 (1.00 g, 0.355 mmol),
CuCI, (3.03 g. 17.8 mmol). and acetone (80 mL). The resultant mixture was
refluxed for 12 h. The volatiles were removed under reduced pressure to give a
dark oily solid. The solid was extracted with hexane (100 mL). The hexane
extract was applied to a 3 cm column of silica gel on a coarse frit and was eluted
with hexane (100 mL) to afford a colorless solution. Removal of the volatile
components under reduced pressure, followed by vacuum drying afforded 2 as
a white powder (0.149 g, 73%). M.p. > 300°C (sublimes) [Ill; l3C('H} NMR
(CDCI,): 6 = 91.46 (s, C,CI,); IR (KBr): G[crn-'] =1386 (m). 1351 (s), 1310
(m), 1095 (w). 928 (w). 811 (w). 703 (s), 564 (w). 409 (s); MS (20 eV): mjz 576
( M i , loo%), the isotope distribution pattern of the parent mass envelope was
identical with the calculated pattern.
3: A 100 mL round-bottom flask was charged with KBr (0.484 g, 4.07 mmol),
bromine (0.208 mL, 4.07 mmol), and water (50 mL). The resultant mixture was
stirred at ambient temperature for 0.5 h, and then l(1.146 g, 0.407 mmol) was
added. The mixture was stirred at ambient temperature for 3 h, during which
time a white precipitate formed. The crude product was collected on a mediumporosity glass frit and washed with methanol (20 mL). The precipitate was then
extracted with dichloromethane (100 mL) to afford a colorless solution. This
solution was applied to a 3 cm pad of silica gel on a coarse glass frit. Elution
with dichloromethane (50 mL) afforded a colorless solution. Removal of the
volatile components under reduced pressure afforded 3 as an analytically pure
white powder (0.194g, 47%). M.p. (sealed tube) > 300°C; "C{'H} NMR
(cDCI,): d = 84.51 (s, C,Br,); IR (KBr): B[crn-'] =1379 (m), 1302 (s), 1274
(w). 589 ( s ) ;MS (20 eV): m/r 1020 ( M ' , loo%), the isotope distribution pattern
of the parent mass envelope was identical with the calculated pattern; correct
C,H analysis.
4: A 100 mL round-bottom flask was charged with KI (0.830 g, 5.00 mmol),
iodine (1.269 g, 5.00 mmol), water (50 mL), and a stir bar. The resultant mixture was stirred at ambient temperature for 1 hand then 1 (1.409 g, 0.50 mmol)
was added. The mixture was stirred at ambient temperature for 5 h, during
which time an orange-colored precipitate formed. The crude product was coilected on a medium-porosity glass frit and was washed with aqueous potassium
iodide (0.1 M, 100 mL), water (20 mL), water (20 mL), and methanol (100 mL)
to remove mercury impurities. The residue was placed in a paper thimble and
was extracted with acetone in a Soxhlet extractor for 24 h to remove additional
mercury impurities. Vacuum drying in a drying pistol for 24 h afforded 4 as a
yellow-ochre powder (0.292 g, 39%). M.p. 240-260 "C (decomposition range);
'3C{iH] NMR ([DJDMSO): 6 = 69.94 (s, CsIs); IR (KBr): F[cm-'] =I246
(m). 506 (m); MS (20eV): m/z 1110 ( [ M - 311'. 3%), the isotope distribution
pattern of the [ M - 311' mass envelope was identical with the calculated pattern; correct C,H analysis.
Received: March 4, 1993 [Z 5903 IE]
German version: Angew. Chem 1993, I M , 1247
[I] For leading references, see: C. W. Fung, R. M. G. Roberts, Tetrahedron
1980, 3289; B. Floris, G. Illuminati, Coord. Chem. Rev. 1975, 16,107; W.
Kitching, Organomer. Chem. Rev. 1968, 3, 35; L . G. Makarova in
Organomerallic Reacrions, Val. I (Eds.: E. I. Becker, M. Tsutsui), WileyInterscience, New York, 1970, p. 119; V. I. Popov, M. Lieb, A. Haas, Ukr.
Khim. Zh. 1990, 56, 1115. See also: G. Amiet, K. Nicholas, R. Pettit, J.
Chem. SOC. Chem. Commun. 1970, 161; A. N. Nesmeyanov, K. N.
Anisimov, 2. P. Valuava, Izv. Akad. Nauk. SSSR Ordel. Khim. Nauk.
1962, 1683; M. D. Rausch, R. A. Genetti, 1 Org. Chem. 1970,35, 3888.
[2] a) M. D. Rausch, E. 0. Fischer, H. Grubert, J. Am. Chem. Sac. 1960,82,
76: b) A. N. Nesmeyanov, A. A. Lubovich, S. P. Gubin, Izv. Akad. Nauk.
SSSR Ser. Khim. 1972, 1823.
[3] W. H. Morrison, D. H. Hendrickson, Inorg. Chem. 1972, 11, 2912; A. I.
Gusev, Y. T.Struchkov. Zh. Strukr. Khim. 1972,6, 1121; L. I. Denisovich,
N. V. Zakurin, A. A. Bezrukova, S . P. Gubin, J Orgunomet. Chem. 1974,
81. 207.
Angett. Chem. Inr. Ed. Engl. 1993, 32, No. 8
[4] C. H. Winter, Y.-H. Han, M. J. Heeg, Organomerallics 1992, 11, 3169. For
the decamercuration of ferrocene, see: V. I. Boev, A. V. Dombrovskii, Zh
Obshch. Khim. 1977, 47, 727; lzv. Vyssh. Uchebn. Zaved. Khim. Khim.
Tekhnol. 1977,20, 1789.
[5] C,,Br,,Ru (3): M =1020.3, triclinic, Pi , a =7.600(2), b = 8.915(3), c =
14.617(5)A, a = 89.50(3), 9, = 84.88(2), y =78.14(2)", V = 965.3(5) A3,
2 = 2, e,,,,, = 3.510 g ~ m - ~(Mo,.)
= 214.97cm-', T = 295 K, 3398
independent reflections with 4" < 2 6 I50" were collected (Siemens P4), of
which 1624 reflections with Fo greater than 50(F,) were used in refinement.
R = 0.0525, R, = 0.060, G O F = 1.19. The centrosymmetric space group
was chosen on the initial basis of E values and was retained on the basis
of the refinement statistics. A semiempirical absorption correction based
on 216data ($-scans of 6reflections at 10" increments) was applied,
T(max)/T(min) = 4.82. There were no unusual bond lengths or angles. All
atoms were refined anisotropically. Further details of the crystal structure
investigation may be obtained from the Fachinformationszentrum Karlsruhe, Gesellschaft fur wissenschaftlich-technische Information mbH, D76 344 Eggenstein-Leopoldshafen (FRG), on quoting the depository number CSD-57327, the names of the authors, and the journal citation.
[6] For crystal structure determinations of complexes containing pentachlorocyclopentadienyl and pentabromocyclopentadienyl ligands, see: a) V. W.
Day, K. J. Reimer, A. Shaver, J. Chem. Sac. Chem. Commun. 1975, 403;
b)G. M. Brown, F. L. Hedberg, H. Rosenberg, ibid. 1972, 5; c) P. G.
Gassman, C. H. Winter, J. Am. Chem. Sac. 1988, 100,6130; d) W. Priebsch, M. Hoch, D. Rehder, Chem. Ber. 1988, 121, 1971. See also: 0.J.
Curnow, R. P. Hughes, J. Am. Chem. SOC.1992, 114, 5895.
[7] A. Bondi, J. Phys. Chem. 1964,68,441.
[8] For selected structure determinations of ruthenocenes, see: P. Seiler, J. D.
Dunitz, Acra Cryslallogr. Secr. B 1980.36.2946; D. C. Liles, A. Shaver, E.
Singleton, M. B. Wiege, J. Organomer. Chem. 1985, 288, C33; J. Trotter,
Acta Crysfallogr.1963, 16, 571; G. Small, J. Trotter, Can. J. Chem. 1964,
42, 1746; H. Schmid, M. L. Ziegler, Chem. Ber. 1976, 109, 125; E. 0.
Fischer, F. J. Gammel, J. 0. Besenhard. A. Frank, D. Neugebauer. J.
Organomer. Chem. 1980, 191, 261.
[9] M. G. Hill, W. M. Lamanna, K. R. Mann, Inorg. Chem. 1991, 30, 4690.
1101 Y. H. Han, C . H. Winter, unpublished results.
[ l l ] F. L. Hedberg, H. Rosenberg, J. Am. Chem. Sac. 1973, 95, 870.
Synthesis and Structure of a
By Kozo Toyota, Katsuya Tashiro, and Masaaki Yoshifuji*
Sterically protected phosphorus-containing multiplebonded comDounds are currentlv of interest. Our studies
have centered on compounds that contain cumulative
double bonds or conjugated n-electron systems with phosphorus atom(s) in low coordination states,[''21 as well as
diphosphenesr31 and ph~sphaethenes.'~]
Recently Appel
et al.,[51Mark1 et a1.,L6]and o ~ r s e l v e s [ have
~ - ~ ~reported the
preparation and isolation of diphosphinidenecyclobutenes 1 a-c, which utilizes 2,4,6-tri-tert-butylphenyl (Ar) as a
protecting group. We now report the synthesis and structure
of a diphosphinidenecyclobutene with an extended n-electron system, namely a diphospha[4]radialene (1,2-dimethylene-3,4-diphosphinidenecyclobutane)
la: R = SiMe3
Ic: R = H
Ar = 2,4,6-tBu3C6H2
Prof. Dr. M. Yoshifuji, Dr. K. Toyota, K. Tashiro
Department of Chemistry, Faculty of Science
Tohoku University, Aoba, Sendai 980 (Japan)
Telefax: Int. code + (22)224-2029
This work was supported in part by the Japanese Ministry of Education,
Science and Culture (Grants-in-Aid for Scientific Research), and Funds
from the Asahi Glass Foundation. We thank Tosoh Akzo Co., Ltd. and
Shin-Etsu Chemical Co., Ltd. for chemicals.
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ruthenocene, decamercuration
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