Polynuclear organometallic helices by means of novel coupling reactions of cyclomanganated complexes with aryl-substituted diazoalkanes: Syntheses of new manganospiralenes and appended (η5-fluoren-9-yl)M(CO)3 complexes (M = Mn, Re)

Article abstract of DOI:10.1021/om020116z

Novel reactions of various cis-(LC)Mn(CO)₄ complexes (LC = a three-electron chelating ligand) with diazodiphenylmethane and 9-diazofluorene allowed the synthesis of a new type of oligomeric polynuclear manganospiralene derived from quinoxaline

Full text of DOI:10.1021/om020116z

Organometallics 2002, 21, 3519-3535
3519
P olyn u clea r Or ga n om eta llic Helices by Mea n s of Novel
Cou p lin g Rea ction s of Cyclom a n ga n a ted Com p lexes w ith
Ar yl-Su bstitu ted Dia zoa lk a n es: Syn th eses of New
Ma n ga n osp ir a len es a n d Ap p en d ed
(η5-flu or en -9-yl)M(CO)3 Com p lexes (M ) Mn , Re)
Christophe Michon,† J ean-Pierre Djukic,*,† Zoran Ratkovic,†,‡ J ean-Paul Collin,§
Michel Pfeffer,*,† Andre´ de Cian,| and J ean Fischer|,
UMR 7513 CNRS, Institut de Chimie de Strasbourg, Universite´ Louis Pasteur 4,
rue Blaise Pascal, F-67070 Strasbourg Cedex, France
Dirk Heiser,# Karl Heinz Do¨tz,*,# and Martin Nieger#,¶
Kekule´ Institut fu¨r Organische Chemie und Biochemie und Institut fu¨r Anorganische Chemie
der Universita¨t Bonn, Gerhard-Domagk Strasse 1, D-53121 Bonn, Germany
Received February 13, 2002
Novel reactions of various cis-(LC)Mn(CO)4 complexes (LC ) a three-electron chelating
ligand) with diazodiphenylmethane and 9-diazofluorene allowed the synthesis of a new type
of oligomeric polynuclear manganospiralene derived from quinoxaline and the ready
preparation of a new class of appended (η5-fluorenyl)Mn(CO)3 complexes. Hence, bis-
cyclomanganated 2,3-diphenylquinoxaline cleanly reacted to afford a dinuclear dispiralene
in which the heterocycle is embedded between two phenyl rings introduced by diphenyldia-
zomethane. The reaction of cyclomanganated and rhenated aromatic compounds with
9-diazofluorene is shown to proceed efficiently under thermolytic conditions, which promote
the departure of one molecule of CO and the subsequent coordination of a fluorenylidene
fragment. Further rearrangements consisting of a cis-migration step and of a series of
haptotropic shifts lead to the final appended (η5-fluorenyl)M(CO)3 complex (M ) Mn, Re).
This new C-C bond-forming reaction has enabled the synthesis of a pentacyclic helical
compound derived from bis-cyclomanganated 2,3-diphenylquinoxaline and whose conforma-
tion could be locked by coordination to Ag+, affording a hybrid inorganic-organometallic
polyhelix. An overview of the electrochemical properties of selected mono- and binuclear
spiralenes is disclosed and shows that most spiralenes display electrochemically reversible
reduction processes. An ESR analysis of the radical anion of a dinuclear spiralene indicated
that the reduction process is ligand-centered and the spin density essentially located at the
heterocycle. The structures of new spiralenes and appended (fluorenyl)M(CO)3complexes,
obtained by crystal X-ray diffraction techniques, are described.
In tr od u ction
obtained by either electrochemical or chemical reduction
or oxidation of organic polymeric substrates. Electrolu-
minescence is another interesting property, which finds
its applications in electronic display devices. Polymers
containing polyaza aromatic units are particularly suit-
able for applications in so-called PLEDs as precursors
for n-doped conducting media and electroluminescent
layers.
Assembled arrays of aromatics obtained by means of
metal coordination at the nanoscale or by large-scale
polymerization are of interest for the design of electro-
active materials for optoelectronics.1 As shown by the
early reports of Heeger and other researchers, n- or
p-doped layers of organic polymers can be readily
* To whom correspondence should be addressed. E-mail: J .-P.D.,
djukic@chimie.u-strasbg.fr; M.P., pfeffer@chimie.u-strasbg.fr; K.H.D.,
doetz@uni-bonn.de.
Our long interest for the chemistry of transition-metal
centers chelated by aza-heterocyclic aromatic ligands2
naturally leads us to consider bringing a contribution
to this swiftly expanding field by applying some of our
recent achievements in the chemistry of Mn(I) chelates.3
The keystone of our project is the chemistry of a new
family of helical organometallic molecules, the metallo-
spiralenes, whose intramolecular ring π-π stacking
feature may establish the base for the design of a new
class of electron conducting medium.4 We recently
† Laboratoire de Synthe`ses Me´tallo-induites.
‡ Permanent address: Faculty of Science of the University of
Kragujevac, R. Domanovica 12, YU-34000 Kragujevac, FR Yugoslavia.
§ Laboratoire de Chimie Organo-Mine´rale.
| Laboratoire de Cristallochimie.
To whom requests pertaining to X-ray diffraction analyses should
be sent. E-mail: for compounds 1b,c, 2b, and 3c-e, J .F. at fischer@
chimie.u-strasbg.fr; for compounds 5a ,c, M.N. at m.nieger@
uni-bonn.de.
#
Kekule´ Institut fu¨r Organische Chemie und Biochemie.
Institut fu¨r Anorganische Chemie.
¶
10.1021/om020116z CCC: $22.00 © 2002 American Chemical Society
Publication on Web 07/23/2002

3520 Organometallics, Vol. 21, No. 17, 2002
Michon et al.
Sch em e 1
reported on the mechanistic issues of the formation of
manganospiralenes, a class of organometallic helical
molecules consisting of a polyaromatic ligand tightly
coiled around a M(CO)3 scaffold.5
These helical molecules arise from the stereoselective
insertion of an alkylidene species into the CAr-Mn bond
of a cyclomanganated cis-(LC)Mn(CO)4 complex, in
which LC stands for a three-electron chelating ligand
(Scheme 1). The alkylidene transient species can be
formed by two different experimental approaches: (1)
the classical “E. O. Fischer method”, which consists of
the sequential treatment of the starting metal-carbonyl
complex with an organolithium nucleophile, followed by
treatment with a hard alkylation agent, and (2) the
thermolysis of the cis-(LC)Mn(CO)4 complex in the
presence of a diazoalkane. We successfully applied the
first method in many cases with various types of
organolithium reagents.6 We found, however, the second
method to be softer and more reliable, as we now aim
in the first stage to build elaborated oligomeric spi-
ralenes and in the second stage to prepare the parent
organometallic polymers.4 Such a method involves
neutral diazoalkanes that have proven their versatility
in numerous applications in organic synthesis as pre-
cursors of reactive triplet alkylidene7 and, of course, in
organometallic chemistry.8 In the present article we
report on novel reactions of various Mn(I) chelates with
diphenyldiazomethane9 and 9-diazofluorene,10 which
allowed the ready preparation of a new class of ap-
pended (η5-fluorenyl)Mn(CO)3 complexes, and on the
synthesis of a new type of oligomeric polynuclear
spiralene3c derived from quinoxaline. We disclose an
overview of the electrochemical properties of selected
mono- and binuclear spiralenes, and we further present
the first synthesis of a hybrid inorganic-organometallic
polyhelix consisting of a single-strand arrangement of
pentacyclic helices locked by metal coordination.
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Resu lts a n d Discu ssion
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n ylp yr id in es. The use of diazoalkanes11 for the syn-
thesis of transition-metal alkylidene complexes was
described by Herrmann and co-workers in the 1970s.12
The method consists of a reaction between a transition-
metal complex possessing at least one available coor-
dination site and an alkylidene precursor such as a
diazoalkane. In reports dealing with M(CO)nLm-type
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Organometallics 1997, 16, 657. (b) Djukic, J . P.; Maisse, A.; Pfeffer,
M. J . Organomet. Chem. 1998, 567, 65. (c) De Cian, A.; Djukic, J .-P.;
Fischer, J .; Pfeffer, M.; Do¨tz, K. H. Chem. Commun. 2002, 638.
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Pfeffer, M.; Do¨tz, K. H.; De Cian, A.; Fischer, J . Chem. Eur. J . 2000,
6, 1064.
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Cian, A.; Fischer, J . Organometallics 2000, 19, 5484.
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M.; De Cian, A.; Fischer, J . Inorg. Chem. 1998, 37, 3649. (c) Djukic, J .
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1994, 63, 197.

Polynuclear Organometallics Helices
Organometallics, Vol. 21, No. 17, 2002 3521
F igu r e 1. (a) ORTEP diagram of complex 1b displayed at the 30% probability level with the corresponding atom numbering.
Hydrogen atoms have been omitted for clarity purposes. Selected interatomic distances (Å): Mn-Cr, 3.047(3); Mn-C18,
2.182(2); Mn-C8, 2.356(2); Mn-N, 2.074(1); Cr-C8, 2.443(2); C8-C18, 1.452(3); C19-C10, 2.896 (3); Mn-C9, 2.904 (3);
Cr-CAr (average), 2.226. Selected interatomic angles (deg): C2-Cr-C3, 93.93(8); C1-Cr-C2, 84.52(9); C1-Cr-C3, 81.46-
(9); C7-C8-C9, 113.9(2). Selected torsion angles (deg): C10-C9-C8-C18, 19.6; C8-C9-C10-N, 38.0. Angles between
mean planes P1 (C10-C11-C12-C13-C14-N), P2 (C9-C8-C7-C6-C5-C4) and P3 (C19-C20-C21-C22-C23-C24)
(deg): P1-P2, 37.6; P1-P3, 37.0. (b) ORTEP diagram of complex 2b displayed at the 30% probability level with the
corresponding atom numbering. Hydrogen atoms have been omitted for clarity purposes. Selected interatomic distances
(Å): Mn-C16, 2.173(2); Mn-C15, 2.221(2); Mn-C10, 2.361(2); Mn-N, 2.019(2); C15-C16, 1.468(3); C4-C23, 2.996(3).
Selected interatomic angles (deg): C14-C15-C10, 114.9(2); N-Mn-C16, 85.67(8). Selected torsion angles (deg): C16-
C15-C10-C4, 12.6; C15-C10-C4-N, 55.2.
complexes, the necessary vacant site at the metal center
is created by the photolytic decoordination of one
molecule of CO.13 The formation of transient metal-
alkylidene species by direct reaction of diazoalkanes
with electron-deficient metal centers constitutes the
essence of “metal-carbenoid” based transformations in
organic synthesis.14 Cyclomanganated complexes of the
formula cis-(LC)Mn(CO)4 can undergo a mono-de-
coordination of CO under chemical,15 photolytic16 or
thermolytic17 conditions enabling thus various sorts of
exogenous ligands to interact with the Mn(I) center. We
previously found that the thermolytic method was
indeed well suited for a reaction between cyclomanga-
nated 2-[tricarbonyl(η6-phenyl)chromium]pyridine (1a )
and diazodiphenylmethane (eq 1).4
(12) (a) Herrmann, W. A. Angew. Chem. 1974, 86, 556; Angew.
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200. (e) Herrmann, W. A. Chem. Ber. 1975, 108, 3412. (f) Herrmann,
W. A. Pure Appl. Chem. 1982, 54, 65. (g) Herrmann, W. A.; Planck, J .;
Kriechbaum, G. W.; Ziegler, M. L.; Pfisterer, H.; Atwood, J . L.; Rogers,
R. D. J . Organomet. Chem. 1984, 264, 327.
(13) (a) Wrighton, M. Chem. Rev. 1974, 74, 401. (b) Strohmeier, W.;
von Hobe, D.; Scho¨nauer, G.; Laporte, H. Z. Naturforsch. 1962, 17b,
502. (c) Strohmeier, W.; Guttenberger, J . F. Chem. Ber. 1964, 97, 1256.
(d) Strohmeier, W.; Guttenberger, J . F. Chem. Ber. 1964, 97, 1871. (e)
Strohmeier, W.; Gerlach, K. Chem. Ber. 1961, 94, 398. (f) Strohmeier,
W.; von Hobe, D. Chem. Ber. 1961, 94, 2031. (g) Giordano, P. J .;
Wrighton, M. S. Inorg. Chem. 1977, 16, 160. (h) Bengali, A. A.
Organometallics 2000, 19, 4000. (i) Braunschweig, H.; Ganter, B. J .
Organomet. Chem. 1997, 545, 163. (j) Hofmann, P. Angew. Chem. 1977,
89, 551; Angew. Chem., Int. Ed. Engl. 1977, 16, 536. (k) Ward, T. R.;
Schafer, O.; Daul, C.; Hofmann, P. Organometallics 1997, 16, 3207.
(l) Young, K. M.; Wrighton, M. S. Organometallics 1989, 8, 1063. (m)
Yang, H.; Asplund, M. C.; Kotz, K. T.; Wilkens, M. J .; Frei, H.; Harris,
C. B. J . Am. Chem. Soc. 1998, 120, 10154. (n) Fischer, E. O.;
Herberhold, M. In Essays in Coordination Chemistry, Exp. Suppl. IX:
Birkenheuser-Verlag: Basel, Switzerland, 1964.
The product, e.g. 1b, which was fully characterized
spectroscopically and analytically, displayed physical
properties similar to those of all known heterobimetallic
spiralenes.4 We succeeded in resolving the structure of
this complex by X-ray diffraction methods. An ORTEP
diagram is shown in Figure 1a. Acquisition and process-
ing data are listed in Table 1. The overall shape of this
heterobimetallic species is helical. The two metals face
each other: the Cr atom occupies one of the equatorial
positions of the pseudo-octahedron centered at the Mn
atom. The Cr-Mn distance of 3.047(2) Å is character-
(14) (a) Doyle, M. P. Chem. Rev. 1986, 86, 919. (b) Doyle, M. P. Recl.
Trav. Chim. Pays-Bas 1991, 110, 305. (c) Tomilov, Yu. V.; Dokichev,
V. A.; Dzemilev, U. M.; Nefedov, O. M. Russ. Chem. Rev. (Engl. Transl.)
1993, 62, 799. (d) Doyle, M. P. In Catalytic Asymmetric Synthesis;
Ojima, I., Ed.; VCH: New York, 1993; pp 63-99. (e) Ye, T.; McKervey,
M. A. Chem. Rev. 1994, 94, 1091. (f) Bernardi, F.; Bottoni, A.; Miscione,
G. P. Organometallics 2000, 19, 5529.
(15) (a) Liebeskind, L. S.; Gadaska, J . R.; McCallum, J . S. J . Org.
Chem. 1989, 54, 669. (b) Cambie, R. C.; Metzler, M. R.; Tutledge, P.
S.; Woodgate, P. D. J . Organomet. Chem. 1990, 381, C28.
(16) Grigsby, W. J .; Main, L.; Nicholson, B. K. Organometallics 1993,
12, 397.
(17) Cambie, R. S.; Metzler, M. R.; Rutledge, P. S.; Woodgate, P. D.
J . Organomet. Chem. 1992, 429, 41.

3522 Organometallics, Vol. 21, No. 17, 2002
Michon et al.
Ta ble 1. Acqu isition a n d Refin em en t Da ta for th e X-r a y Diffr a ction An a lyses of Com p lexes 1b,c, 2b, 3c-e,
a n d 5a ,ca
1b
1c
2b
3c
3d
3e
5a
5c
formula
C
30H18Cr-
MnNO6
C30H16Cr-
MnNO6
C28H20Mn-
NO3
C52H32
-
C52H28
-
C53H31AgMn2- C19H10Cr-
C32H18Cr-
NO7Re
Mn2N2O6
Mn2N2O6‚
N2O6‚BF4‚
NO7Re
CH2Cl2
2CH3OH
mol wt
cryst syst
595.42
monoclinic
593.40
monoclinic
473.41
ortho-
890.72
monoclinic
971.62
ortho-
rhombic
1176.48
ortho-
rhombic
602.48
monoclinic
766.67
triclinic
rhombic
Pbca
11.8883(2)
17.0308(2)
21.9813(4)
space group
a (Å)
b (Å)
P21/c
P21/c
P21/n
Pbca
P212121
P21/c
P1h
8.9761(2)
14.3301(5)
19.8900(7)
9.6538(3)
15.0319(5)
17.5379(5)
15.6887(7)
16.7698(9)
15.9857(7)
14.8379(2)
35.4532(3)
16.3323(5)
13.6186(5)
15.1375(7)
25.032(1)
14.5814(5)
7.1064(1)
18.5035(6)
10.6761(1)
15.5375(2)
16.4606(2)
76.462(1)
85.527(1)
84.046(1)
2636.22(5)
4
c (Å)
R (deg)
â (deg)
γ (deg)
V (Å3)
Z
100.134(6)
100.773(5)
93.588(5)
106.175(1)
2518.5(3)
4
2500.2(1)
4
4450.5(1)
8
4197.5(3)
4
8591.6(3)
8
5160.5(4)
4
1841.46(9)
4
color
cryst dimens
(mm)
red
orange
0.18 ×
0.12 ×
0.08
1.58
1200
red
dark blue
0.20 ×
0.14 ×
0.10
1.41
1824
yellow
0.16 ×
0.13 ×
0.10
red
orange
0.25 ×
0.15 ×
0.10
2.173
1144
orange
0.20 ×
0.10 ×
0.04
1.932
1488
0.20 ×
0.09 ×
0.05
0.20 ×
0.20 ×
0.16
0.12 ×
0.10 ×
0.08
Dcalcd (g cm-3
)
1.57
1.41
1.50
1.51
F000
1208
0.980
173
1952
0.624
173
3952
0.769
173
2372
0.930
173
µ (mm-1
)
0.987
173
0.657
294
7.201
123
5.054
123
temp. (K)
scan mode
hkl limits
ψ scans
-11 to +11/
-17 to +18/
-25 to +25
2.5-27.46
10 143
-12 to +12/
-17 to +19/
-22 to +22
2.5-27.46
10 230
-16 to +16/
-22 to +22/
-30 to +30
2.5-30.03
12 128
-20 to +20/
-21 to +20/
-20 to +20
2.5-27.51
16 708
-19 to +19/
-21 to +21/
-45 to +45
2.5-27.48
19 157
-17 to +17/
-19 to +19/
-32 to +32
2.5-27.48
11 811
-17 to +17/
-8 to +7/
-22 to +22
2.91-25.00
15 396
-12 to +12/
-18 to +18/
-19 to +19
2.55-25.00
57 909
θ limits (deg)
no. of data
measd
no. of unique
data
4184
3727
3412
3947
3614
3656
3245
9270
no. of variables 352
352
298
559
586
634
263
759
R
Rw
0.028
0.033
0.060
1.073
0.357
0.036
0.050
1.057
0.404
0.035
0.040
1.040
0.289
0.051
0.082
1.415
0.589
0.058
0.080
1.513
0.959
0.0210
0.0563
1.110
1.762
0.0266
0.0711
1.037
1.225
0.040
1.011
0.562
GOF
largest peak
in final diff
map (e Å-3
)
a
All measurements were performed with a Nonius KappaCCD diffractometer using Mo KR graphite-monochromated radiation (λ )
0.710 73 Å).
istic of a weak intermetal interaction and remains in
the heterocycle is an additional indication of the helical
shape of the molecule. In the structure depicted in
Figure 1b, the inter-ring distance C4-C23 has a value
of 2.996 Å. A solution IR spectrum of 2b, carried out in
CH2Cl2, further ascertains that the Mn(I) center is
bonded to the two above-mentioned aromatic carbon
atoms of the phenylpyridine ring: the CO stretching
band at 2000 cm-1 is typical of mononuclear Mn(I)
spiralenes.
Rea ction of P h 2CN2 w ith P r o-Helica l Bis-Cyclo-
m a n ga n a ted 2,3-Dip h en ylqu in oxa lin e. Bir th of a
Hom om eta llic Bis-Ma n ga n osp ir a len e. It is well
established that the conformational stability of helicenes
depends on the number of fused rings.19 It is also
directly related to geometrical parameters such as the
pitch, the number of turns, and the radius of the helix,
which defines with the handedness the “chirality” of
helicenes.20 Among all helicenes, pentahelicenes possess
the lowest barriers to conformational change and a
dynamic behavior in solution. Bis-cyclometalated 2,3-
diphenylquinoxaline and -pyrazine complexes can be
considered as dimetalla analogues of pentahelicenes.
Cyclopalladated 2,3-diphenylpyrazine, for example, has
been prepared, studied, and structurally characterized
the range of previously reported data.6 An interplanar
angle of 37° and the C10-C19 distance of 2.896(3) Å
characterize the overlap of one phenyl ring and the
pyridyl ring. The shortest distances between the last
two mean planes are indeed lower than the optimal
distance of 3.6 ( 0.1 Å observed in most cases for
parallel face-to-face π-π stacking interactions.18
The mononuclear complex 2a displayed a similar
behavior when treated with Ph2CN2 in refluxing n-
heptane (eq 2). The orange-yellow product of the reac-
tion was readily identified as the mononuclear spiralene
1
2b (Figure 1b). A combination of IR, H and 13C NMR,
and X-ray diffraction analyses assessed that in solution
as well as in the solid state the Mn(I) center is bonded
to the benzylic position (atom C16 in Figure 1b) and the
two vicinal aromatic carbons (atoms C15 and C10) of
the phenylpyridine fragment. The temperature depen-
dence of the shape and multiplicities of 1H NMR signals
of 2b produced by the overlap of one phenyl group with
(19) (a) Laarhoven, W. H.; Prinsen, W. J . C. In Stereochemistry;
Vo¨gtle, F., Weber, E., Eds.; Springer-Verlag: Berlin, 1984; p 63. (b)
J anke, R. H.; Haufe, G.; Wu¨rthwein, E. U.; Borkent, J . H. J . Am. Chem.
Soc. 1996, 118, 6031.
(20) Katzenelson, O.; Edelstein, J .; Avnir, D. Tetrahedron: Asym-
metry 2000, 11, 2695.
(18) Hunter, C. A. Chem. Soc. Rev. 1994, 23, 101.

Polynuclear Organometallics Helices
Organometallics, Vol. 21, No. 17, 2002 3523
by Steel and Caygill.21 Its helicity in the solid state has
been shown to stem from the steric repulsion operating
on the two palladated phenyl groups connected at the
2- and 3-positions of the pyrazine ring. Actually, in
solution, the latter pentacyclic Pd(II) complex is con-
formationally fluxional and exists under two swiftly
exchanging and equally populated forms of helices of
M and P handedness (in eq 3 the complex is drawn in
Sch em e 2
a Newman-type side view). As a consequence, such an
achiral fluxional helical system may be qualified as
being “pro-helical” rather than strictly helical.
metalating this heterocyclic ligand, neither with MeMn-
(CO)5 nor with (PhCH2)Mn(CO)5.
It is worth noting that the introduction of factors of
asymmetry in such a system could putatively modify
the population of the two isomers in solution, thus
enabling stereoselective reactions at the metal centers.
The stereochemical course of any reaction occurring in
the coordination sphere of each chelated metal should
be conditioned by the intrinsic conformational and steric
requirements of the substrate. As will be shown below,
the bis-manganation of ligand 3a affords a dinuclear
complex 3b, for which the structural features resemble
those of the Pd(II) analogue mentioned above (eq 4). The
The purple dinuclear complex 3b displayed good
stability to air and reacted smoothly with an excess
amount of Ph2CN2 in a mixture of boiling toluene and
n-heptane (eq 5). Unexpectedly, the color of the medium
quickly changed from deep purple to dark blue. The
product, 3c, was separated by conventional flash chro-
matography and recovered as an air-stable dark blue
powder. Obtaining crystals suitable for X-ray diffraction
analyses was complicated by the high solubility of 3c
in aliphatic nonpolar solvents. Only the slow evapora-
tion of an n-heptane solution of 3c at 4 °C afforded
crystals of sufficient quality.
Figure 2 displays an ORTEP diagram of complex 3c
with the atom-numbering scheme. The structure of this
binuclear complex indicates clearly that the reaction of
the 2 equiv of Ph2CN2 took place on opposite faces of
the substrate 3b: in other words, in an anti fashion (eq
5). In complex 3c, the heterocycle is embedded between
the two endo phenyl rings (Figure 3). The stacking of
the aromatic rings is characterized by interplanar
angles of ca. 20° and distances between centroids of
vicinal rings of ca. 3.4 Å (Figure 3). The phenylene rings
are twisted by a value of ca. 50° with respect to the
central heterocycle and are mutually involved in CH-π
interactions23 via the hydrogen atoms located at C21
and C50, respectively. The distortion of an η3 type bond
involving the organic ligand and the two manganese(I)
centers is similar to that previously encountered with
other manganospiralenes. The distortion of the geom-
etry of 3c from ideal C2 symmetry suggests some strains
stemming from crystal packing.
twisting of the two phenyl groups and by extension the
“pro-helicity” of 3b is expected to influence the stereo-
chemical course of the reaction with the diazoalkane R2-
CN2. The sequential double addition of R2CN2 in an anti
fashion (with respect to the mean plane of the chelate
3b) is rather favored, as it results in an increase of the
torsion angle between the planes of the two phenyl
groups and the heterocycle, thus yielding a less steri-
cally congested product (Scheme 2). A syn fashion
double addition of the diazoalkane is disfavored, since
it leads to a more sterically congested system (Scheme
2).
The bis-cyclomanganation of 2,3-diphenylquinoxaline
3a was achieved by carrying out the reaction with
(PhCH2)Mn(CO)5 at reflux of n-heptane. We observed
that the reaction conditions should be slightly forced by
reacting a concentrated mixture of a stoichiometric
amount of (PhCH2)Mn(CO)5 (2 equiv) and 3a over ca.
20 h, which contrasts with an earlier report by Bruce
and co-workers,22 who did not succeed in doubly ortho-
(23) (a) Nishio, M.; Hirota, M.; Umezawa, Y. In The CH/ π Interac-
tion, Evidence, Nature and Consequences; Wiley-VCH: New York,
1998. (b) Umezawa, Y.; Tsuboyama, S.; Takahashi, H.; Uzawa, J .;
Nishio, M. Tetrahedron 1999, 55, 10047.
(21) Steel, P. J .; Caygill, G. B. J . Organomet. Chem. 1990, 395, 359.
(22) Bruce, M. I.; Goodall, B. L.; Matsuda, I. Aust. J . Chem. 1975,
28, 1259.

3524 Organometallics, Vol. 21, No. 17, 2002
Michon et al.
F igu r e 2. ORTEP diagram of complex 3c displayed at the 30% probability level. Hydrogen atoms have been omitted for
clarity purposes. Selected interatomic distances (Å): Mn1-N1, 2.057(3); Mn1-C4, 2.161(4); Mn1-C17, 2.203(3); Mn1-
C22, 2.401(3); Mn2-N2, 2.043(3); Mn2-C33, 2.154(4); Mn2-C46, 2.220(3); Mn2-C51, 2.388(3). Torsion angle absolute
value (deg): C22-C23-C52-C51, 8.5. Selected angles between mean planes P1 (C34-C35-C36-C37-C38-C39), P2 (N1-
C23-C52-N2-C25-C26-C27-C28-C29-C24), P3 (N1-C23-C52-N2-C25-C24), and P4 (C51-C50-C49-C48-C47-
C46) (deg): P1-P2, 22.3; P3-P4, 53.5. Distance between centroids, Cgn, of planes Pn (Å): Cg1-Cg3, 3.43 Å.
F igu r e 3. Representations of complex 3c: (a) a sketch outlining the helical shape; (b) space-filling representation
emphasizing the intramolecular stacking of aromatic rings.
Th er m olytic Rea ction of 9-Dia zoflu or en e w ith
cis-(LC)Mn (CO)4 Com p lexes: New Meth od for th e
Syn th esis of Ap p en d ed η5-Coor d in a ted F lu or e-
n yls. Diazocyclopentadienyl24 and its indenyl25a and
fluorenyl25b analogues have been intensively studied for
their reactivity with transition-metal centers. As far as
mononuclear rhenium carbonyl and manganese carbo-
nyl type complexes are concerned, Herrmann and co-
workers carried out the very first investigations in the
1970s.12 The most recent achievements have been made
in the late 1990s.26 Katzenellenbogen and co-workers
synthesized a variety of appended tricarbonyl(η5-cyclo-
pentadienyl)rhenium analogues as well as other tech-
(25) (a) Rewicki, D.; Tuschcherer, C. Angew. Chem. 1972, 84, 31.
(b) Pfeiffer, J .; Nieger, M.; Do¨tz, K. H. Chem. Eur. J . 1998, 4, 1843. (c)
Pfeiffer, J .; Do¨tz, K. H. Organometallics 1998, 17, 4353. (d) Pfeiffer,
J .; Do¨tz, K. H. Angew. Chem. 1997, 109, 2948; Angew. Chem., Int. Ed.
Engl. 1997, 36, 2828. (e) Pfeiffer, J .; Nieger, M.; Do¨tz, K. H. Eur. J .
Org. Chem. 1998, 1011.
(24) (a) Doering, W. v. E.; DePuy, C. H. J . Am. Chem. Soc. 1953,
75, 5955. (b) Weil, T.; Cais, M. J . Org. Chem. 1963, 28, 2472.

Polynuclear Organometallics Helices
Organometallics, Vol. 21, No. 17, 2002 3525
netium derivatives by an elegant “one pot” procedure
consisting of a reaction between a XL3M(CO)3 complex
(X ) a one-electron ligand, L ) a two-electron ligand),
diazocyclopentadiene, N2C5H4, and a “nucleophile”, Nu,
such as an arylboronic acid. In a comprehensive report27
the authors demonstrated that the formation of the final
appended RCpM(CO)3 complex results from the reaction
of N2C5H4 with a putative Nu-ML3(CO)3 species via a
transient metal-alkylidene intermediate. The latter
evolves by cis migration of Nu on the carbene carbon to
give a η1-Cp intermediate, which undergoes a series of
ring slippages to afford the final η5-Cp complex. This
multistep mechanism strongly resembles the one we
have established for the formation of manganospi-
ralenes5 and confirms the major role played by transient
alkylidene-type species.
We decided to study the behavior of cis-(LC)Mn(CO)4
versus the readily available 9-diazofluorene, which can
be made by oxidation of fluorene hydrazone with yellow
HgO. For instance, the treatment of complex 1a with
9-diazofluorene in a refluxing mixture of n-heptane and
toluene afforded the heterobimetallic compound 1c in
54% yields (eq 6). In this reaction the diazoalkane
F igu r e 4. ORTEP diagram of complex 2c given at the 40%
probability level. Hydrogen atoms have been omitted for
clarity purposes. Selected interatomic distances (Å): Cr-
C12, 2.229(3); Cr-C11, 2.260(3); Cr-C10, 2.212(3); Cr-
C9, 2.215(3); Cr-C8, 2.207(3); Cr-C7, 2.206(3); Mn-C18,
2.137(3); Mn-C19, 2.180(3); Mn-C24, 2.197(3); Mn-C25,
2.198(3); Mn-C26, 2.199(3). Metal to plane centroid dis-
tances (π-coordinated ligands) (Å): Mn-Cg, 1.8051(14); Cr-
Cg, 1.7168(13). Selected angles between mean planes P1
(C12-C11-C10-C9-C8-C7), P2 (N-C13-C14-C15-
C16-C17), and P3 (C18-C19-C24-C25-C26) (deg): P1-
P2, 77.4; P2-P3, 38.8.
undergoes a competing decomposition into dimerization
products,28 which can challenge the C-C coupling
reaction with the cyclometalated substrate. The proce-
dure was optimized significantly by using mixtures of
aliphatic solvents and toluene and by reacting ca. 2
equiv of diazoalkane in a boiling solution containing the
starting complex. The course of the reaction could be
monitored by IR spectroscopy. The experiment was
stopped when the IR measures indicated the disappear-
ance of the characteristic four CO stretching bands of
the Mn(CO)4 fragment of the substrate and the clear
appearance of two new CO stretching bands corre-
sponding to a typical fac-L3M(CO)3 species beside the
two CO stretching bands originating from the Cr(CO)3
group. The change in color of the reaction medium was
also a good indicator of the rate of the reaction. In the
case of the reaction of 1a with 9-diazofluorene, the color
of the medium changed from deep red to canary yellow
in ca. 30 min. The product, e.g. complex 1c, could be
successfully recrystallized to afford a suitable sample
for X-ray diffraction analyses. Figure 4 presents an
ORTEP diagram of compound 1c.
by the corresponding planes P1(C11-C12-C7-C8-C9-
C10) and P3(C18-C19-C24-C25-C26); the correspond-
ing interplanar angle P1-P3 is 77.4°. The nitrogen atom
of the pyridyl fragment points outward, probably as a
result of an electrostatic repulsion with the π system of
the vicinal fluorenyl group. This effect added to the
hindrance caused by the 1,2-substitution pattern of the
Cr-bound phenylene group disables a trans relationship
between the two M(CO)3 fragments, as observed by
Quian29 in a similar but less hindered case.
Scheme 3 rationalizes the mechanism of formation of
1c. The first step is the departure of one molecule of
CO from the starting M(CO)4 moiety and its replace-
ment by the Fischer-type electrophilic alkylidene frag-
ment. The second step is the cis migration of the aryl
group bonded to the central metal atom and the forma-
tion of a labile Mn(I) chelate that can readily undergo
several haptotropic shifts and rearrangements between
various η3 bonding modes (vide infra). The key step is
clearly the cleavage of the N-Mn bond. The driving
force of the overall process is the formation of a stable
(η5-fluorenyl)Mn(CO)3 species.
In Figure 4, one can notice the particular arrange-
ment of the two metal-bound aromatic rings represented
Complex 2a reacted similarly with 9-diazofluorene (eq
7). The reaction was carried out in pure refluxing
(26) (a) Minutolo, F.; Katzenellenbogen, J . A. J . Am. Chem. Soc.
1998, 120, 13264. (b) Spradau, T. W.; Katzenellenbogen, J . A. Orga-
nometallics 1998, 17, 2009. (c) Minutolo, F.; Katzenellenbogen, J . A.
Angew. Chem. 1999, 111, 1730. (d) Cesati, R. R.; Katzenellenbogen, J .
A. J . Am. Chem. Soc. 2001, 123, 4093. (e) For a case involving Re2-
(CO)8(MeCN)2 see: Arce, A. J .; Muchado, R.; De Sanctis, Y.; Isea, R.;
Atencio, R.; Deeming, A. J . J . Organomet. Chem. 1999, 580, 339.
(27) Minutolo, F.; Katzenellenbogen, J . A. Organometallics 1999,
18, 2519.
(28) Bertani, R.; Michelin, R. A.; Mozzon, M.; Sassi, A.; Basato, M.;
Biffis, A.; Martinati, G.; Zecca, M. Inorg. Chem. Commun. 2001, 4,
281.
toluene and afforded the polar (η5-fluorenyl)Mn(CO)3

3526 Organometallics, Vol. 21, No. 17, 2002
Michon et al.
Sch em e 3
species appended with a 2-(3′-methylpyridin-2′-yl)phe-
nyl group, e.g. 2c, in 62% yield. The chiral complex 4a 4
reacted readily with 9-diazofluorene (eq 8) to give in 85%
yield the corresponding (η5-fluorenyl)Mn(CO)3 deriva-
tive, whose chirality was evidenced by polarimetry ([R]D-
(293 K) ) -33 ( 1° dm-1 g-1 mL).
The cyclorhenated complex 5a 6c also reacted with
9-diazofluorene (eq 9). The reaction was slower than in
with fac-(η1-C5H5)Re(CO)3(PMe3)2.30 Intramolecular clut-
tering caused by the Re(CO)4-bound ligand accounts for
the particularly long Cr-C11 distance of 2.337(4) Å.
On the basis of our experience of the chemistry of Mn-
(I) and Re(I) chelates, we thought it unlikely that
compound 5c could arise from a direct homolytic cleav-
age of the CAr-Re bond in 5a followed by a coupling
with some “alkylidenoid” species. We carried out an
additional experiment aiming at proving that complex
5c stems from a reaction of 5b with dissolved CO. Such
a hypothesis would imply that formation of 5c results
from successive haptotropic shifts of the fluorenyl-bound
rhenium center upon coordination of both endogenous
and exogenous ligands. Such processes are well docu-
mented for CpM(CO)3-type complexes (M ) Mn, Re).31
A concise mechanistic proposal is provided in Scheme
4. In a first step, the endogenous ligand L coordinates
the Re center and induces an η5-η3 haptotropic shift.
In a second step, the intermediate equilibrates with a
η1-type isomer, presenting a vacant coordination site.
Dissolved carbon monoxide arising from the decomposi-
tion of some reactive species bonds to the rhenium atom
in the last step to give the chelated cis-(LC)Re(CO)4
product. This proposal was checked by submitting a
solution of 5b to heat under an atmosphere of CO.
Within a few minutes, IR spectral analysis of the
reaction mixture indicated the conversion of 5b into 5c
the case of the manganese analogue 1a . In fact, not only
did the experiment require longer reaction times to
reach optimum conversion, but also the medium under-
went some decomposition and the overall conversion
was quite low. Chromatographic separation of the crude
mixture afforded minute amounts of the starting com-
plex and delivered two new reaction products. The
structures of the last two compounds (eq 9), 5b,c, were
assessed firmly only after analyses of their respective
13C NMR spectra and the X-ray diffraction analysis of
a crystal of 5c. Figure 5b displays the structure of
complex 5c, and Figure 5a presents an unprecedented
ORTEP diagram of substrate 5a , which is given for
comparison purposes. The structure of complex 5a is
typical of cyclorhenated aromatics. The molecule, which
possesses no peculiar distortions, presents geometrical
trends that are similar to those of known Mn(I) ana-
logues. The particularly long Cr-C8 interatomic dis-
tance of 2.334(3) Å mostly arises from the steric
hindrance created by the Re(CO)4 fragment. The aro-
matic rings are slightly twisted by a value of 16.2° for
the corresponding torsion angle C8-C7-C1-N. In
complex 5c (Figure 5b), the two metal carbonyl frag-
ments are positioned anti to each other. The coordina-
tion environment about the rhenium atom is nearly
octahedral. The six-membered metallacycle consisting
of atoms Re-C13-C11-C6-C5-N adopts a folded
envelope-like conformation. The valence angles around
atom C13 do not fully fit the standard features of a
carbon sp3 type hybridization, although the Re-C13
distance of 2.357(4) Å corresponds to that of a single
Re-CCp bond distance (2.360(10) Å) found, for instance,
(29) Quian, C.; Guo, J .; Sun, J .; Chen, J .; Zheng, P. Inorg. Chem.
1997, 36, 1286.
(30) Casey, C. P.; O’Connor, J . M.; J ones, W. D.; Haller, K. J .
Organometallics 1983, 2, 535.
(31) (a) Stradiotto, M.; McGlinchey, M. J . Coord. Chem. Rev. 2001,
219-221, 311. (b) Casey, C. P.; Kraft, S.; Powell, D. R. Organometallics
2001, 20, 2651. (c) Abernethy, C. D.; Cowley, A. H.; J ones, R. A.;
Macdonald, C. L. B.; Shukla, P.; Thompson, L. K. Organometallics
2001, 20, 3629. (d) Veiros, L. F. Organometallics 2000, 19, 5549. (e)
Khayatpoor, R.; Shapley, J . R. Organometallics 2000, 19, 2382. (f) Lee,
S.; Lovelace, S. R.; Cooper, N. J . Organometallics 1995, 14, 1974. (g)
Biagioni, R. N.; Luna, A. D.; Murphy, J . L. J . Organomet. Chem. 1994,
476, 183. (h) Treichel, P. M.; J ohnson, J . W. Inorg. Chem. 1977, 16,
749. (i) Lee, S.; Cooper, N. J . J . Am. Chem. Soc. 1991, 113, 716. (j)
Casey, C. P.; O’Connor, J . M. Chem. Rev. 1987, 87, 307. (k) Basolo, F.;
Rerek, M. E.; J i, L. N. Organometallics 1984, 3, 740. (l) Yezernitskaya,
M. G.; Lokshin, B. V.; Zdanovich, V. I.; Lobanova, I. A.; Kolobova, N.
E. J . Organomet. Chem. 1982, 234, 329. (m) Casey, C. P.; O’Connor,
J . M. Organometallics 1985, 4, 384. (n) King, R. B.; Efraty, A. J .
Organomet. Chem. 1970, 23, 527. (o) Casey, C. P.; Kraft, S.; Kavana,
M. Organometallics 2001, 20, 3795.

Polynuclear Organometallics Helices
Organometallics, Vol. 21, No. 17, 2002 3527
Sch em e 4
Sch em e 5
d in a tion P olym er . Complex 3b was treated with
9-diazofluorene to subsequently afford the new bimetal-
lic product 3d (Scheme 5). The reaction was carried out
in pure toluene, and 3d was recovered in 79% yield after
chromatographic purification. A color change from deep
purple to canary yellow took place within the few
minutes that followed the addition of 2 equiv of 9-dia-
zofluorene. We recrystallized 3d and submitted a crystal
to X-ray diffraction analysis. An ORTEP diagram of 3d
is presented in Figure 6.
The structure of 3d is clearly helical in shape as a
result of the compact arrangement of the three central
1,2-disubstituted aromatics. The two Mn(CO)3 moieties
point outward to minimize steric interactions and allow
stabilizing intramolecular π-π stacking. The overall
“molecular compactness” can be described by the in-
tramolecular π-π contacts existing between the free
face of the two (η5-fluorenyl)Mn(CO)3 groups and the
two phenylene fragments. In the crystal lattice, 3d is
packed in a columnar fashion, intermolecular interac-
tion being established between Mn(CO)3 moieties of
each molecule. As can be noticed in Figure 6, a quite
cluttered environment surrounds the two nitrogen
atoms of the heterocycle. The geometry of 3d deviates
slightly from the ideal C2-type symmetry. These discrete
distortions consist of slight twists and folding such as
the dihedral angle C25-C26-C29-C34, which amounts
to 3.1°.
F igu r e 5. (a) ORTEP diagram of complex 5a given at the
30% probability level. Hydrogen atoms have been omitted
for clarity purposes. Selected interatomic distances (Å): Cr-
C7, 2.207(3); Cr-C8, 2.334(3); Cr-C9, 2.259(3); Cr-C10,
2.201(3); Cr-C11, 2.211(3); Cr-C12, 2.201(3); Re-C8,
2.169(3); Re-N, 2.202(2). Selected interatomic angles (deg):
C9-C8-C7, 117(3); C8-Re-N, 75.73(10). Selected torsion
angles (deg): C8-C7-C1-N, 16.2(4); C1-C7-C8-Re,
10.7(3). (b) ORTEP diagram of complex 5c given at the 30%
probability level. Hydrogen atoms have been omitted for
clarity purposes. The geometrical data of one molecule of
the asymmetric unit are given. Selected interatomic dis-
tances (Å): Re1-N1, 2.227(3); Re1-C13, 2.357(4); Cr1-
C6, 2.266(4); Cr1-C7, 2.206(4); Cr1-C9, 2.189(4); Cr1-
C10, 2.202(4); C11-C13, 1.505(6). Metal-to-centroid distance
(Å): Cr1-Cg, 1.725(3). Selected interatomic bond angles
(deg): C25-C13-C14, 102.2(3); C10-C11-C6, 115.8(4).
Selected values of absolute torsion angles (deg): N1-C5-
C6-C11, 44.4(6); C5-C6-C11-C13, 3.8(6).
and the presence of some other minor species that could
not be identified. Furthermore, we observed that, upon
cooling and replacement of the CO blanket by argon,
the medium would evolve to afford the starting complex
5b. This result conspicuously confirms that the decom-
position process taking place in the reaction between
5a and 9-diazofluorene actually provides the carbon
monoxide that is incorporated into 5b to give 5c. To the
best of our knowledge, complex 5c represents one new
case of rhenium(I) complex in which the fluorenyl ligand
is η1-bonded to the metal center.
Quinoxalines, pyrazines, and other bis-monodentate
ligands based on two interconnected pyridine rings are
often used in the synthesis of inorganic-organic hybrid
polymers,32 applied in crystal engineering and derived
in the synthesis of electroluminescent organic polymers.
When silver cation is used as the “cement”, these ligands
are also appropriate synthons for the construction of
single-strand linear hybrid inorganic/organic polymers
and even more sophisticated supramolecular assem-
Syn th esis of a n Or ga n om eta llic Qu in oxa lin e: A
F lu xion a l Helix Lock ed by In clu sion in to a Coor -

3528 Organometallics, Vol. 21, No. 17, 2002
Michon et al.
Sch em e 6
stabilize the helical architecture and gain a higher
conformational stability, the dynamic conformational
change has to be restricted by dramatically increasing
the energetic barrier to interconversion. With 3d , this
can be achieved by locking the molecular helix through
an increase of the degree of substitution at the two
nitrogen atoms of the central heterocycle, either by
current methods of organic chemistry, i.e., by bis-
alkylation of the two N atoms, or by means of coordina-
tion chemistry methods, i.e., by bonding these hetero-
atoms to the electrophilic metal “M” (Scheme 6).
We chose the second method. In our hands, the
reaction of 3d with stoichiometric amounts of AgBF4 in
acetone cleanly afforded, after slow crystallization, a
new bright red linear hybrid inorganic/organometallic
polymer 3e (Scheme 5). The latter displayed a reason-
able stability to air. Surprisingly, in this reaction we
did not notice any decomposition of 3d that could have
been initiated by the known oxidizing properties of Ag+
salts. Slow recrystallization of a crude sample of 3e from
a THF/MeOH solution by diffusion in n-heptane af-
forded crystals suitable for the X-ray diffraction analy-
sis. An ORTEP diagram of 3e is displayed in Figure 7
with a detailed atom-numbering scheme.
F igu r e 6. ORTEP diagram of complex 3d given at the 40%
probability level. Molecules of solvent and hydrogen atoms
have been omitted for clarity purposes. Selected inter-
atomic distances (Å): Mn1-C15, 2.147(8); Mn1-C7, 2.190-
(7); Mn1-C14, 2.201(7); Mn1-C13, 2.207(7); Mn1-C12,
2.233(7). Selected interatomic angles (deg): C14-C15-C7,
105.5(6); C15-C14-C13, 110.5(6); C14-C13-C12, 106.8-
(7); C13-C12-C7, 107.9(6). Absolute value of torsion angle
C25-C26-C29-C34 (deg): 3.1(12).
blies.33 As shown in Figure 6, complex 3d contains a
quinoxaline nucleus shielded by the two (η5-fluoren-9-
yl)Mn(CO)3 fragments. Of course, such a conformation
must be considered as a limit, since free rotation of these
aromatic fragments is allowed in solution (Scheme 6).
It is understood that one given (η5-fluorenyl)Mn(CO)3
group changes its position only in synergy with the other
one, in a so-called flip-flop movement (Scheme 6). To
Polymer 3e crystallizes in the noncentrosymmetric
space group P212121. In the analyzed crystal of 3e, each
local coordinated helix is of M handedness. Figure 7
shows an emphasized view of one polymeric single
strand with the atom-numbering scheme. Similarly to
(32) (a) Schmaltz, B.; J ouaiti, A.; Hosseini, M. W.; De Cian, A. Chem.
Commun. 2001, 1242. (b) Fitchett, C. M.; Steel, P. J . New J . Chem.
2000, 24, 945. (c) Maggard, P. A.; Stern, C. L.; Poeppelmeier, K. R. J .
Am. Chem. Soc. 2001, 123, 7742. (d) Bourne, S. A.; Kilkenny, M.;
Nassimbeni, L. R. J . Chem. Soc., Dalton Trans. 2001, 1176. (e)
Hartmann, H.; Berger, S.; Winter, R.; Fiedler, J .; Kaim, W. Inorg.
Chem. 2000, 39, 4977. (f) Blake, A. J .; Champness, N. R.; Crew, M.;
Parsons, S. New J . Chem. 1999, 13. (g) Blake, A. J .; Champness, N.
R.; Khlobystov, A. N.; Lemenovskii, D. A.; Li, W. S.; Schro¨der, M. Chem.
Commun. 1997, 1339.
(33) (a) Khlobystov, A. N.; Blake, A. J .; Champness, N. R.; Lemen-
ovskii, D. A.; Majouga, A. G.; Zyk, N. V.; Schro¨der, M. Coord. Chem.
Rev. 2001, 222, 155. (b) Munakata, M.; Wu, L. P.; Ning, G. L. Coord.
Chem. Rev. 2000, 198, 171. (c) Klein, C.; Graf, E.; Hosseini, M. W.; De
Cian, A. New J . Chem. 2001, 25, 207. (d) Lo¨ı, M.; Hosseini, M. W.;
J ouaiti, A.; De Cian, A.; Fischer, J . Eur. J . Inorg. Chem. 1999, 1981.
(e) Kaes, C.; Hosseini, M. W.; Rickard, C. E. F.; Skelton, B. W.; White,
A. H. Angew. Chem. 1998, 110, 970; Angew. Chem., Int. Ed. Engl. 1998,
37, 920.

Polynuclear Organometallics Helices
Organometallics, Vol. 21, No. 17, 2002 3529
F igu r e 8. Stick-type diagram displaying a portion of a
strand of the hybrid inorganic-organometallic polymer
3e: (a) view from the top, showing the alternating qui-
noxaline rings in a “head-to-tail” configuration; (b) view
from the side, showing the zigzag shape conferred to the
polymeric chain by the coordination of one molecule of
MeOH (not shown) to the Ag center. The solvated MeOH
-
as well as disordered BF4 have been omitted for clarity
purposes.
F igu r e 7. ORTEP diagram of a unit of polymer 3e drawn
at the 20% probability level. The solvated MeOH molecule,
disordered BF4- molecule, and hydrogen atoms have been
omitted for clarity purposes. Selected interatomic distances
(Å): Ag-N1, 2.251(9); Ag-N2, 2.281(9); Ag-O7, 2.32(1);
Mn1-C28, 2.14(1); Mn1-C29, 2.19(1); Mn1-C34, 2.19(1);
Mn1-C35, 2.22(1); Mn1-C40, 2.19(1); Mn2-C42, 2.19(1).
Selected valence angles (deg): N1-Ag-N2, 141.3(3); N1-
Ag-O7, 109.4(4); N2-Ag-O7, 109.2(4); C29-C28-C40,
106(1). Selected absolute torsion angle (deg): C21-C20-
C13-C12, 3.4(14); C20-C21-C28-C41, 1.3(16). Selected
angles between mean planes P1 (C20-C13-C19-C14-
N1-N2a), P2 (C7-C12-C11-C10-C9-C8), P3 (C28-
C29-C34-C35-C40), P4 (C21-C22-C23-C24-C25-C26)
(deg): P3-P4, 12.8; P2-P4, 56.9; P3-P2, 44.9; P1-P2, 57.1.
Selected distances between centroids of corresponding
planes (Å): Cg3-Cg4, 3.59; Cg3-Cg1, 4.66.
with a 2-acetylphenyl fragment at the 9 position, e.g.
6b in 82% yield (eq 10). Further advances on this topic
shall be disclosed in due time.
Electr och em ical Beh avior of Man gan ospir alen es.
The electrochemical properties of several spiralenes
were studied by cyclic voltammetry in CH3CN and THF,
using mostly a polished flat Pt-bead working electrode.
Electrochemical data are reported in Table 2. Complexes
1b, 2b, and 7-11 (Chart 1) all displayed only one
reversible reduction wave at potentials higher than -1.8
V vs SCE (saturated calomel electrod), while oxidation
proved to be in most cases irreversible electrochemically,
likely as a result of a metal-centered ECE-type process
(Table 2).36 Anodic/cathodic peak-potential separations
for the processes related to reduction in cyclic voltam-
metry experiments were found to depend on the nature
of both the working electrode and the solvent. Smaller
∆E (∆E ) Ep,c - Ep,a) values, e.g. close to the value of
59 mV for a monoelectronic process, could be obtained
with a hanging-Hg-drop working electrode. The high
values of ∆E obtained with a Pt-bead electrode can be
related to uncompensated solution resistance and to
3d , in each subunit of the polymer, the pentacyclic
ligand adopts the shape of an helix. The polymer is not
strictly linear, as can be seen in Figure 8. Indeed,
coordination of one molecule of MeOH per silver atom
induces a zigzag shape, which is often observed with
other Ag+-based coordination polymers. This red poly-
mer was analyzed by IR spectroscopy: a spectrum taken
with a KBr pellet sample of 3e displayed no difference
from a reference spectrum of 3d measured under the
same conditions, thus suggesting there is no significant
effect of the coordinated silver atom on the electron
density at the manganese atoms.
The above-mentioned results motivate us now to
closely investigate the synthetic application of such a
new carbon-carbon bond-forming reaction, to address
the reactivity of other cyclomanganated complexes
versus diazocyclopentadiene derivatives, and to study
the chemical properties of this new class of appended
CpMn(CO)3-like complexes for which a few examples
have already been reported.34 For instance, the reaction
of the acetophenone derivative 6a 35 with 9-diazofluorene
affords a new (η5-fluorenyl)Mn(CO)3 complex appended
(34) (a) Top, S.; Kaloun, E. B.; Toppi, S.; Herrbach, A.; McGlinchey,
M. J .; J aouen, G. Organometallics 2001, 20, 4554 and references
therein. (b) Le Bideau, F.; Salmain, M.; Top, S.; J aouen, G. Chem. Eur.
J . 2001, 7, 2289. (c) Enders, M.; Kohl, G.; Pritzkow, H. J . Organomet.
Chem. 2001, 622, 66.
(35) (a) McKinney, R. J .; Firestein, G.; Kaesz, H. D. Inorg. Chem.
1975, 14, 2057. (b) Knobler, C. B.; Schreiber-Crawford, S.; Kaesz, H.
D. Inorg. Chem. 1975, 14, 2062.
(36) Herschberger, J . W.; Amatore, C.; Kochi, J . K. J . Organomet.
Chem. 1983, 250, 345.

3530 Organometallics, Vol. 21, No. 17, 2002
Michon et al.
Ta ble 2. Ch a r a cter iza tion of Va r iou s Sp ir a len es a n d An a logu es by Cyclic Volta m m etr y
Hg hanging drop
working electrode, acetonitrile
E1/2(redn) (∆E)
Pt-bead working electrode, acetonitrile
Pt-bead working electrode, THF
compd
E
1/2(redn) (∆E)
-1.58 (0.33)
scan rate
E(oxidn)
E1/2(redn) (∆E)
scan rate
100
E(oxidn)
1b
2b
3c
-1.67 (0.12)
-1.04 (0.06)d
-0.93 (0.16)
-1.69 (0.11)
-1.56b
100
100
+0.78b
+1.04b
+1.01b
+1.19b
+0.72b
-0.90 (0.11)
-1.83 (0.12)
200
3d
7
8
9
10
11
-1.39 (0.95)
-1.56 (0.99)
-1.37 (0.10)
-1.69b
100
100
100
400
100
-1.43 (0.23)
200
200
-1.04 (0.07)c
-1.56 (0.17)
+0.75b
-1.61 (0.17)
+0.24b
Potentials are expressed in V vs SCE and scan rates in mV s-1
.
Slow or nonreversible system. c Scan rate 200 mV s-1
.
Scan rate
a
b
d
100 mV s-1
.
Ch a r t 1
partial adsorption of reduced species on the surface of
the Pt electrode. However, at this stage of our study,
we cannot rule out the possible existence of underlying
ECE processes similar to those evidenced by Amatore,
Ceccon, and co-workers37 with a parent system, i.e., syn-
and anti-facial {µ-(1,2,3,4,5,6-η:7,8,9-η)]-indenyl}(CO)3Cr-
Rh(cod) complexes. Most measures carried out with
heterobinuclear spiralenes displayed in reduction the
classical behavior of reversible systems though. In all
cases, the variation of the peak current associated with
the reduction wave(s) with the scan rate was that of a
reversible electrochemical system.
Interestingly, complex 3c displayed at room temper-
ature in THF two electrochemically reversible reduction
waves at -0.90 and -1.83 V vs SCE (Figure 9a)
similarly to unsubstituted quinoxaline in DMF as
reported by Mubarak and Peters.38a This contrasts with
the behavior of 2,3-diphenylquinoxaline, which is known
to undergo only one-electron reversible reduction at
-1.63 V vs SCE.38b It is worthy to note that further
reduction of 2,3-diphenylquinoxaline at a more negative
cathodic potential leads to a reactive dianion, which
irreversibly evolves by a C-C coupling reaction to yield
the corresponding dibenzo[a,c]phenazine dianion.39 Simi-
F igu r e 9. Cyclic voltammetry of spiralenes at room
temperature (Pt-bead working electrode, Pt-wire counter
electrode, Ag-wire pseudo reference electrode, a 0.1 N
solution of (n-Bu)4NPF6 as support electrolyte): (a) volta-
mmogram of a THF solution of complex 3c containing
ferrocene as internal reference (1.66 × 10-4 M, 200 mV s-1);
(b) voltammogram of a solution of complex 9 in CH3CN
(2.50 × 10-3 M, 100 mV s-1) containing ferrocene as
internal reference.
larly, 2-ferrocenyl-3-phenylquinoxalines undergo an ir-
reversible two-electron-reduction process leading to
untraceable products.40
By carrying out controlled-potential electrolysis ex-
periments and cyclic voltammetry-based titrations with
solutions of compounds 8 and 3c in CH3CN at room
temperature, we could ascertain that the spiralene’s
reduction process involved the transfer of one electron.
Complexes 3c and 8 were reduced at a spiral-shaped
Pt wire at -1.20 and -1.60 V vs SCE, respectively. For
the electrolysis of 8 in CH3CN the decay of the cathodic
current as a function of time followed the expected
exponential decay (see the Supporting Information). The
transfer of one electron per molecule (0.25 C) of 8 was
(37) Amatore, C.; Ceccon, A.; Santi, S.; Verpeaux, J . N. Chem. Eur.
J . 1999, 5, 3357.
(38) (a) Mubarak, M. S.; Peters, D. G. J . Electroanal. Chem. 2001,
507, 110. (b) Bock, H.; J ohn, A.; Na¨ther, C.; Ruppert, K. Helv. Chim.
Acta 1994, 77, 1505.
(39) Rabinovitz, M.; Cohen, Y.; Meyer, A. Y. J . Am. Chem. Soc. 1986,
108, 7039.
(40) Zanello, P.; Fontani, M.; Ahmed, S. Z.; Glidewell, C. Polyhedron
1998, 17, 4155.

Polynuclear Organometallics Helices
Organometallics, Vol. 21, No. 17, 2002 3531
complete, under these conditions, after ca. 580 s of
electrolysis. After this period of time a slight increase
of the cathodic current was observed, which was symp-
tomatic of the degradation of the radical anion 8-. A
similar experiment carried out with 4.38 × 10-3 mmol
of 3c led to the observation of a complete transfer of
one electron per molecule of 3c (0.42 C) after ca. 1000 s
of electrolysis.
A complementary comparative cyclic voltammetry
was carried out with a solution of 8 (3.32 × 10-3 M)
using the hexafluorophosphate salt of methyl viologen
(c(PQ2+,2PF6-) ) 2.62 × 10-3 M) as a reference. The
latter displays two consecutive one-electron reversible
redox processes.41 The values of the ratios Ip,c/Ip,a for the
two couples PQ2+/PQ+ and PQ+/PQ corresponding to the
two one-electron processes were estimated, within ex-
perimental errors, as 1.2 and 1.0, respectively. A value
of 1.0 for the Ip,c/Ip,a ratio of the couple 8/8- was also
determined (see the Supporting Information). A solution
of a mixture of 8 and PQ2+,2PF6- (ratio of concentrations
c(PQ2+,2PF6-)/c (8) ) 0.79) afforded the value of 0.80
F igu r e 10. Solvatochromism of complex 3c in the region
450-700 nm characterized by the variation of the extinc-
tion coefficient ꢀ (dm2 mol-1) and the value of λmax (nm)
with the polarity of the solvent: (-) in hexane (9.8 × 10-5
M, λmax 586 nm, ꢀ586 ) 5.0 × 104); (- - -), in dichloromethane
(9.8 × 10-5 M, λmax 569 nm, ꢀ569 ) 2.8 × 104); (‚‚‚) in
acetonitrile (9.4 × 10-5 M, λmax 561 nm, ꢀ561 ) 2.5 × 104).
for the two ratios of cathodic peak currents Ip,c(PQ2+
/
PQ+)/Ipc(8/8-) and Ip,c(PQ+/PQ)/Ipc(8/8-), thus further
supporting the notion that reduction of 8 involves one
electron.
2. The values of KC in acetonitrile (KC(CH3CN,298 K)
) 7.9 × 1012, ∆E1/2 ) 0.76 V) and in tetrahydrofuran
(KC(THF,298 K) ) 6.2 × 1015, ∆E1/2 ) 0.93 V) are typical
of a radical anion of the class III in which the “single”
electron is delocalized between the two manganese
centers over the bridging diaza heterocycle.43
Complex 3c is a blue compound which displays a net
negative solvatochromism44 associated with the rela-
tively intense metal-to-ligand charge-transfer transition
(MLCT) band located at ca. 590 nm, as illustrated in
Figure 10. Negative solvatochromism understands that
more polar solvents stabilize more the ground state than
the excited state, thus leading to a decrease of both the
wavelength and the extinction coefficient of the corre-
sponding transition.45 However, solvatochromism of a
binuclear nonpolar complex such as 3c questions the
nature of both the ground and the Franck-Condon
excited states.46
A similar system has been studied by Kaim and co-
workers: the binuclear dark blue and air-sensitive
complexes of the formula (CpR)(CO)2Mn(pyrazine)Mn-
(CO)2(CpR).47 The latter revealed some similarities in
their spectrochemical properties with Ru(II) analogues.
The authors reported only one reversible reduction wave
at around -1.38 V vs SCE that is at potentials more
negative than those reported herein for 3c but close to
those reported for uncoordinated pyrazine38a (-1.40 V
in DMF with a glassy-carbon working electrode). Wor-
thy of note, the authors did not report any other
reduction wave at a more negative potential.
In the heterobimetallic Cr(0)/Mn(I) complexes 7 and
9 the potentials of couples 7/7- and 9/9- are more
positive by a value of ca. 190 mV than for those of the
corresponding mononuclear analogues 11/11- and 8/8-.
This increase in potential can be intuitively correlated
to the known electron-accepting properties of the Cr-
(CO)3 moiety or interpreted by a significant lowering of
the energy of the LUMO, which with likelihood is
centered at the heterocyclic ligand of the considered
binuclear species. It must be recalled that typical (η6-
arene)Cr(CO)3 complexes undergo irreversible two-
electron-reduction processes, yielding a reactive dia-
magnetic dianion.42
Red u ction of 3c. In acetonitrile, the reduction of 3c
affords successively the radical anion 3c- (E ) -0.93
V) and the anion 3c2- (E ) -1.69 V), as demonstrated
before by cyclic voltammetry. This behavior is reminis-
cent of that observed in mixed-valence compounds43 that
incorporate a pyrazine unit as bridge between two
metallic ions or radicals in identical environments. The
issues related to spin density localization and an anal-
ogy with the so-called mixed-valence species were
preliminarily addressed by determining the compropor-
tionation constant KC for the process
3c + 3c2- a 2 3c-
(KC ) 10∆E/0.059, with ∆E in V) from the electrochemical
potentials of couples 3c/3c- and 3c-/3c2- given in Table
Chemical reduction of a solution of 3c in THF by
reaction with a potassium mirror revealed a spectral
(41) (a) Michaelis, L. Biochem. Z. 1932, 250, 564. (b) Michaelis, L.;
Hill, E. S. J . Am. Chem. Soc. 1933, 55, 1491. (c) Michaelis, L. J . Prakt.
Chem. 1959, 9, 164.
(42) (a) Rieke, R. D.; Arney, J . S.; Rich, W. E.; Willeford, B. R.;
Poliner, B. S. J . Am. Chem. Soc. 1975, 97, 5951. (b) Rieke, R. D.; Henry,
W. P.; Arney, J . S. Inorg. Chem. 1987, 26, 420.
(44) (a) Drago, R. S. J . Chem. Soc., Perkin Trans. 2 1992, 1827. (b)
Drago, R. S. J . Org. Chem. 1992, 57, 6547. (c) Drago, R. S.; Hirsh, M.
S.; Ferris, D. C.; Chronister, C. W. J . Chem. Soc., Perkin Trans. 2 1994,
219. (d) Marcus, Y. Chem. Soc. Rev. 1993, 22, 409. (e) Thomas, J . A.;
Hutchings, M. G.; J ones, C. J .; McCleverty, J . A. Inorg. Chem. 1996,
35, 289.
(45) Developments in the Chemistry and Technology of Organic
Dyes; Griffiths, J ., Ed.; Blackwell Scientific: Oxford, U.K., 1983.
(46) Dodsworth, E. S.; Lever, A. B. P. Coord. Chem. Rev. 1990, 97,
271.
(43) (a) Richardson, D. E.; Taube, H. Inorg. Chem. 1981, 20, 1278.
(b) Richardson, D. E.; Taube, H. Coord. Chem. Rev. 1984, 60, 107. (c)
Ward, M. D. Chem. Soc. Rev. 1995, 121. (d) Kaim, W.; Klein, A.;
Glo¨ckle, M. Acc. Chem. Res. 2000, 33, 755. (e) Demadis, K. D.;
Hartshorn, C. M.; Meyer, T. J . Chem. Rev. 2001, 101, 2655. (f) Lambert,
C.; No¨ll, G. J . Am. Chem. Soc. 1999, 121, 8434. (g) Bonvoisin, J .;
Launay, J . P.; Rovira, C.; Veciana, J . Angew. Chem. 1994, 106, 2190;
Angew. Chem., Int. Ed. Engl. 1994, 33, 2106.
(47) Gross, R.; Kaim, W. Inorg. Chem. 1986, 25, 498.

3532 Organometallics, Vol. 21, No. 17, 2002
Michon et al.
tigated by Kaim and Gross, the values of g for three
Mn(I) complexes, whose differences are ascribed to
different degrees of substitution at the Cp fragment, are
lower than that of the free electron (ge ) 2.002 32).49
McConnell’s postulate defines a linear relationship
between hyperfine coupling constants and the π-spin
population in aromatic radical ions. A comparison of the
hyperfine coupling constants a(H) and a(14N) assigned
to the radical anion 3c- with the values reported by
Bock and co-workers for the radical anion of 2,3-
diphenylquinoxaline (a(H5,8) ) 2.39 G, a(H6,7) ) 1.40 G,
a(14N) ) 5.25 G) clearly suggests a lower π-spin density
at the benzo fragment of the quinoxaline nucleus of 3c
and a significant transfer of spin density to the two
nitrogen atoms and the two manganese centers. A
similar fact has been pointed out for the pyrazine-based
dinuclear Mn(I) complexes by Kaim and Gross, who
furthermore underscored the absence of spin density at
the surrounding Cp ligands. With the radical anion 3c-,
we seemingly have a similar situation where spin
density is negligible both at the two phenylene frag-
ments and at the two endo-phenyl groups overlapping
the heterocycle. This is not exceptional, as the π-system
presents discontinuities at the benzylic positions and
at the junction of the heterocycle with the two twisted
phenylene groups. Therefore, like 3c, the dinuclear
radical anion 3c- is homovalent.
F igu r e 11. Spectral changes of a THF solution of complex
3c (c ≈ 2.75 × 104 Μ, ꢀ568 ≈ 4 × 104) upon reduction over
a potassium mirror (absorption vs wavelength in nm):
continuous curve, solution of 3c in THF; dashed curve,
spectrum after reaction with K. Main changes in the
absorption spectrum occur in the 400-750 nm region.
Con clu sion
In this article we report on new C-C bond-forming
reactions between a series of cyclometalated aromatic
ligands and the two symmetrically substituted diazoal-
kanes Ar2CN2. These reactions are promoted by heat,
which enables the partial decarbonylation of the cis-
(LC)Mn(CO)4 substrate, thus creating a vacant coordi-
nation site. The formation of a metal-alkylidene inter-
mediate is followed by a series of molecular rearrange-
ments that lead in one case (Ar2CN2 ) (C6H5)2CN2) to
stable chelated (η3-trihaptobenzyl)Mn(CO)3 complexes
and in the other case (Ar2CN2 ) C12H8CN2) to a new
class of stable mono- and dinuclear appended (η5-
fluorenyl)Mn(CO)3 complexes. In most cases these reac-
tions are efficient and the conversions are higher than
50%. These new coupling reactions might show some
interesting applications, especially for the synthesis of
organometallic C-C bond-based polymers. For this
latter purpose, bis-diazoalkanes and poly-cyclometa-
lated aromatics are the substrates of choice. Of course,
we have shown here only the results pertaining to the
use of two symmetrically substituted diaryldiazoal-
kanes. We are currently addressing the stereoselectivity
issues raised by the use of unsymmetrically substituted
diazoalkanes and further investigate the synthetic
applications of our new method of preparation of
substituted CpM(CO)3-type complexes described herein.
Electrochemical studies of various mono- and dinuclear
spiralenes demonstrate that reduction processes are
F igu r e 12. Measured (a) and simulated (b) X-band ESR
spectra of the radical anion 3c- (c ≈ 1.1 × 10-3 Μ, g )
2.003 45) in THF at 293 K, formed by reaction of 3c with
potassium metal: microwave power, 2 mW; modulation
frequency, 100 kHz; modulation amplitude, 0.5 G; sweep
time, 83.9 s.
dependence of the solute over its oxidation state in
solution. This reduction reaction induced relevant
changes in the 400-750 nm region of the visible ab-
sorption spectrum in THF (Figure 11) and clearly
obliterated the MLCT transition of 3c observed at 570
nm in THF.
An X-band ESR analysis of a solution containing
reduced 3c indicated the presence of a paramagnetic
species, putatively 3c-, having a half-life time of ca. 30
min, at 298 K, under an argon atmosphere. A value of
2.003 45 was determined for the g factor (Figure 12a).
Unfortunately, all our attempts at acquiring ENDOR
spectra and therefore at gaining a better estimation of
the aCH hyperfine coupling constants failed so far.
However, the hyperfine structures were thoroughly
analyzed from the ESR spectrum (Figure 12a), satis-
factorily simulated,48 and refined (Figure 12b). The
following hyperfine coupling constants were extracted,
considering that spin density was very probably es-
sentially located mostly at the quinoxaline nucleus and,
to a lesser extent, at the two metal centers: a(55Mn,I )
(48) Winsim program from the Public EPR Software Tools distribu-
tion (National Institute of Environmental Health Sciences, http://
EPR.niehs.nih.gov): Duling, D. R. J . Magn. Reson., Ser. B 1994, 104,
105.
(49) (a) Weil, J . A.; Bolton, J . R.; Wertz, J . E. In Electron Paramag-
netic Resonance, Elementary Theory and Practical Applications;
Wiley: New York, 1994. (b) Kaim, W. Inorg. Chem. 1984, 23, 3365. (c)
Gerson, F. In Hochauflo¨sende ESR-Spektroskopie, dargestellt anhand
aromatischer Radikal-Ionen; Fo¨rst, W., Gru¨newald, H., Eds.; Verlag
Chemie: Weinheim, Germany, 1967.
3
5/2) ) 4.6 G, a(14N, I ) /2) ) 6.1 G, a(H,C-H) ) 1.3 G,
a(H,CH) ) 1.6 G. In the pyrazine-based system inves-

Polynuclear Organometallics Helices
Organometallics, Vol. 21, No. 17, 2002 3533
Coulometric experiments were carried out using a cell consist-
ing of a spiral-shaped Pt wire as cathode, a straight Pt wire
as anode, and a KCl-saturated calomel reference electrode. The
last two were separated from the solution containing the
analyte by a bridge consisting of a fritted-glass tube containing
a 0.1 M solution of supporting electrolyte. Cathodic reductions
were carried out at a potential ca. 200 mV lower than the E1/2
potential of the studied redox couple.
Exp er im en ta l P r oced u r e for th e X-r a y Diffr a ction
An a lysis of Com p ou n d s 1b,c, 2b, 3c-e, a n d 5a ,c. Acquisi-
tion and processing parameters are displayed in Table 1.
Reflections were collected with a Nonius KappaCCD diffrac-
tometer using Mo KR graphite-monochromated radiation (λ
) 0.710 73 Å). The structures of 5a and 5c were refined on
F2: the programs used for structure solution and refinement
were SHELXS97 and SHELXL-97.51 For both compounds 5a
and 5c an empirical absorption correction was applied (mini-
mum/maximum transmission 0.3227/0.4063 (5a ) and 0.5026/
0.6296 (5c)). The other structures were solved using direct
methods and were refined against |F|, and for all pertaining
computations the Nonius OpenMoleN package was used.52
Hydrogen atoms were introduced as fixed contributors. The
absolute structure of 3e was determined by refining Flack’s x
parameter (x ) 0.03).
Gen er a l P r oced u r e for Rea ction s of Cyclom eta la ted
Su bstr a tes w ith Dia r yld ia zom eth a n es. The complex was
dissolved in either pure n-heptane or toluene (or a mixture of
both). The resulting solution was brought to reflux, and a sol-
ution of diaryldiazomethane in toluene was added dropwise
via a syringe. The reaction mixture was further stirred, the
solution was cooled to room temperature, and the solvents
were evaporated under reduced pressure. The crude residue
was dissolved in CH2Cl2, and SiO2 was added to the resulting
solution. The solvent was removed under reduced pressure and
the coated silica gel loaded on the top of a chromatographic
column packed in hexane at subambient temperature for fur-
ther separation of the main product from organic byproducts.
P r ep a r a tion of 2-[Tr ica r bon yl{η6-2′-[tr ica r bon yl(η5-
flu o r e n -9-y l)m a n g a n e s e (I )]p h e n y l}c h r o m i u m (0)]-
p yr id in e (1c). Conditions and reagents for this reaction are
as follows: complex 1a (200 mg, 0.43 mmol), heptane (10 mL),
toluene (10 mL), ebullition; 9-diazofluorene (168 mg, 0.87
mmol) in toluene (5 mL), dropwise addition over 30 min via a
syringe; further stirring for 1 h. The crude residue was dis-
solved in CH2Cl2, and SiO2 was added to the resulting solution.
Chromatography on SiO2 at 10 °C: 1c (1:1 CH2Cl2/acetone),
recrystallization (CH2Cl2/hexane), air-stable bright yellow-
mostly ligand-based and involve the reversible transfer
of one electron. With complex 3c, the scaffolds constist-
ing of coordinated Mn(CO)3 fragments prevent the
aromatic groups surrounding the central heterocycle
from coupling.
The electron-accepting character of these helical
complexes motivates further studies of their application
in the building of electroactive materials, whereby
conduction is based on charge transport mechanisms
such as those suspected for DNA, i.e. charge “hopping”.50
Spiralenes consist of intramolecular stacks of covalently
linked nonconjugated aromatic rings, for which elec-
tronic properties (Lewis-type acceptors or donors) can
be varied by the judicious choice of substituents at both
precursor substrates: in the future, this property could
be used for the synthesis of spiralene-type prototypes
of molecular charge-transfer complexes, by the reaction
of (LC)Mn(CO)4 complexes containing an electron-
accepting pyrazine or quinoxaline nucleus, such as in
3b, with diazoalkanes bearing a strong electron donor
aromatic such as tetrathiafulvalenyl or benzotetrathi-
afulvalenyl. Further studies are now underway to
evaluate such applications.
Exp er im en ta l Section
Gen er a l Con sid er a tion s. All experiments were carried out
under a dry atmosphere of argon with dry and degassed
solvents. Starting (η6-arene)tricarbonylchromium complexes
were synthesized according to published procedures.3,6d NMR
1
spectra were acquired on Bruker DRX 500 (13C and H nuclei)
and AC 300 (1H nucleus) spectrometers at room temperature
unless otherwise stated. Chemical shifts are reported in parts
per million downfield of Me4Si. X-Band ESR spectra (9.376 11
GHz) were recorded at room temperature with a Bruker ESP
300 spectrometer using a 3 mm inner-diameter sample tube
loaded under argon with a freshly prepared analyte. IR spectra
were measured with a Perkin-Elmer FT spectrometer. Mass
spectra were recorded at the Service of Mass Spectrometry of
the University Louis Pasteur (FAB+) and at the Analytical
Center of the Chemical Institute of the University of Bonn (EI).
Elemental analyses (reported in percent mass) were performed
at the Service d’Analyses of the “Institut de Chimie de
Strasbourg” and at the analytical center of the “Institut
Charles Sadron” in Strasbourg.
Electr och em ica l Exp er im en ts. All electrochemical ex-
periments were carried out at room temperature (25 °C) under
an atmosphere of argon with a Princeton Applied Research
273 potentiostat (Model 270/250) computer-controlled with a
EGCS Research Electrochemistry software version 4.23. Tetra-
n-butylammonium hexafluorophosphate was used as support-
ing electrolyte in 0.1 M solutions of dry and deaerated solvents.
orange crystals (140 mg, 54% yield). Anal. Calcd for C24H16
NO6CrMn: C, 60.74; H, 2.36; N, 2.72. Found: C, 60.40; H, 2.29;
N, 2.76. IR (CH2Cl2): ν(CO) 2021 (m), 1969 (s), 1936 (m), 1897
-
1
3
(m) cm-1. H NMR (CDCl3): δ 8.36 (d, 1H, J ) 3.2 Hz), 8.14
3
3
3
(t, 2H, J ) 7.5 Hz), 7.97 (d, 1H, J ) 8.5 Hz), 7.50 (t, 1H, J
3
3
) 7.7 Hz), 7.30 (t, 1H, J ) 7.6 Hz), 7.10 (t, 1H, J ) 7.3 Hz),
6.92-6.85 (m, 4H), 6.54 (d, 1H, 3J ) 7.3 Hz), 6.47 (d, 1H, 3J )
Solid n-Bu4N+PF6 was dried under vacuum for 2 days at 70
-
3
3
6.3 Hz, HArCr), 6.07 (d, 1H, J ) 6.1 Hz, HArCr), 5.87 (t, 1H, J
) 6.1 Hz, HArCr), 5.66 (t, 1H, 3J ) 6.2 Hz, HArCr). 13C NMR
(CDCl3): δ 232.7, 224.3, 153.9, 148.9, 135.0, 128.6, 127.2, 125.4,
125.3, 124.9, 124.7, 123.9 (2C), 123.6, 123.0, 112.2, 107.3,
106.3, 102.7, 101.4, 95.1, 94.8, 92.4, 91.5, 90.7, 78.0.
°C prior to use in electrochemical experiments. Cyclic volta-
mmetry experiments were carried out under an atmosphere
of Ar using an undivided cell comprising a ca. 2 mm diameter
Pt-bead working electrode, a 1 mm diameter Pt wire as counter
electrode, and a ca. 1 mm diameter Ag wire as the pseudo-
reference electrode. Unless otherwise stated, measures were
referenced against the ferrocene-ferrocenium (Fc+/Fc) couple.
Values of potentials were extrapolated against the SCE.
Syn th esis of Tetr a ca r bon yl[3-m eth yl-2-(p h en yl-KC2′)-
p yr id in e-KN]m a n ga n ese(I) (2a ). A solution of (PhCH2)Mn-
(CO)5 (5.64 g, 19.7 mmol) and 3-methyl-2-phenylpyridine (4.0
g, 23.6 mmol) in dry and degassed heptane (25 mL) was
brought to reflux and stirred for 24 h. The resulting mixture
was cooled to room temperature and the solvent evaporated
under reduced pressure. The crude oily mixture was redis-
(50) (a) Grinstaff, M. W. Angew. Chem., Int. Ed. 1999, 38, 3629;
Angew. Chem. 1999, 111, 3845. (b) Ly, D.; Sanii, L.; Schuster, G. B. J .
Am. Chem. Soc. 1999, 121, 9400. (c) Giese, B. Acc. Chem. Res. 2000,
33, 631. (d) Giese, B.; Spichty, M. Chem. Phys. Chem. 2000, 1, 195. (e)
Grozema, F. C.; Berlin, Yu. A.; Siebbeles, L. D. A. J . Am. Chem. Soc.
2000, 122, 10903. (f) Berlin, Yu. A.; Burin, A. L.; Ratner, M. A. J . Am.
Chem. Soc. 2001, 123, 260. (g) Bixon, M.; J ortner, J . J . Am. Chem.
Soc. 2001, 123, 12556. (h) Cai, Z.; Gu, Z.; Sevilla, M. D. J . Phys. Chem.
B 2000, 104, 10406.
(51) (a) SHELXS97: Sheldrick, G. M. Acta Crystallogr.. Sect. A 1990,
46, 467. (b) Sheldrick, G. M. SHELXL-97; University of Go¨ttingen,
Go¨ttingen, Germany, 1997.
(52) Fair, C. K. In MolEN: An Interactive Intelligent System for
Crystal Structure Analysis; Nonius: Delft, The Netherlands, 1990.

3534 Organometallics, Vol. 21, No. 17, 2002
Michon et al.
1
3
solved in CH2Cl2 and silica gel added to the resulting solution.
The solvent was removed under reduced pressure and the coat-
ed SiO2 loaded on the top of a silica gel column packed in dry
deaerated hexane. A yellow band containing 2a was eluted
with a 7:3 CH2Cl2/hexane mixture. Evaporation of the solvents
afforded compound 2a as a pure yellow solid (3.74 g, 50%
yield). Anal. Calcd for C16H10NO4Mn: C, 57.33; H, 3.01; N, 4.18.
Found: C, 57.43; H, 3.05; N, 4.14. IR (CH2Cl2): ν(CO) 2074 (m),
(s), 1941 (s). H NMR (CDCl3): δ 8.59 (m, 2H), 8.19 (d, 2H, J
3
) 7.3 Hz), 7.99 (d, 2H, J ) 8.0 Hz), 7.80 (m, 2H), 7.28 (t, 2H,
3J ) 7.3 Hz), 7.01 (t, 2H, J ) 8.1 Hz). 13C NMR (CDCl3, 263
3
K): δ 220.6 (CO), 213.9 (CO), 212.7 (CO), 181.1, 161.9, 149.3,
141.5, 131.6, 130.9, 130.6, 127.6, 123.6, 115.1.
Syn th esis of lk-{2,3-Di[1′2′7′:η-2′-(d ip h en ylm eth ylen e)-
p h en yl]qu in oxa lin e-KN1,KN2}bis(tr ica r bon ylm a n ga n ese-
(I)) (3c). A solution of diphenyldiazomethane (784 mg, 4 mmol)
in toluene (5 mL) was added to a boiling solution of 3b (411
mg, 0.67 mmol) in a 1:4 heptane/toluene mixture within 10
min. The color of the medium quickly changed from deep
purple to dark blue. The solution was further stirred for 30
min and subsequently cooled to room temperature. The
solvents were evaporated under reduced pressure, and the
crude residue was dissolved in CH2Cl2. Silica gel was added
to the resulting dark solution and the solvent evaporated
subsequently. The coated silica gel was loaded on the top of a
SiO2 column packed in hexane. The main blue band containing
3c was eluted with pure CH2Cl2. Evaporation of the solvent
afforded compound 3c as a dark blue powder (358 mg, 60%
yield) soluble in almost any organic solvent. Crystals suitable
for X-ray diffraction analysis were obtained at +4 °C by the
slow evaporation of a solution of 3c in pure n-heptane. Anal.
Calcd for C52H32N2O6Mn2: C, 70.12; H, 3.65; N, 3.15. Found:
C, 70.17; H, 3.65; N, 3.04. High-resolution MS (FAB+): calcd
for C52H32N2O6Mn2 890.102 13, found 890.101 33. IR (CH2-
Cl2): ν(CO) 2000 (m), 1931 (s), 1907 (s) cm-1. UV-visible
(hexane; λmax, nm (ꢀ, dm2 mol-1)): 351 (1.17 × 105), 586 (5.0 ×
104). UV-visible (CH2Cl2; λmax, nm (ꢀ, dm2 mol-1)): 347 (7.4 ×
104), 569 (2.8 × 104). UV-visible (CH3CN; λmax, nm (ꢀ, dm2
mol-1)): 344 (6.8 × 104), 561 (2.5 × 104) nm. 1H NMR
(CDCl3, 273 K): δ 7.87 (broad d, 4H, Ho-Ph,exo), 7.60 (m, 2H,
1
1989 (s), 1974 (s), 1929 (s) cm-1. H NMR (CDCl3, 400 MHz):
3
3
δ 8.77 (d, 1H, J ) 5.4 Hz), 8.06 (m, 2H), 7.63 (d, 1H, J ) 7.6
3
3
Hz), 7.28 (t, 1H, J ) 7.5 Hz), 7.22 (d, 1H, J ) 7.6 Hz), 7.03
(t, 1H, 3J ) 6.6 Hz), 2.80 (s, 3H). 13C NMR (CDCl3, 100 MHz):
δ 220.2 (CO), 214.2 (2CO), 213.9 (CO), 176.2, 164.8, 152.1,
148.5, 142.2, 141.7, 132.6, 129.2, 128.5, 123.6, 121.5, 24.0.
P r ep a r a t ion of Tr ica r b on yl{3-m et h yl-2-[1′,2′,7′-η:2-
(d ip h en ylm et h ylen e)p h en yl]p yr id in e-KN}m a n ga n ese-
(I) (2b). Conditions and reagents for this reaction are as
follows: complex 2a (400 mg, 1.43 mmol), n-heptane (10 mL),
ebullition; diazodiphenylmethane (1.18 g, 5.71 mmol), toluene
(5 mL), dropwise addition over 30 min; further stirring under
reflux for 1 h. Chromatography with a SiO2 column packed in
dry hexane at 5 °C: 2b (CH2Cl2), recrystallization from ether
and hexane, orange powder (376 mg, 63% yield). Anal. Calcd
for C28H20NO3Mn: C, 71.04; H, 4.26; N, 2.96. Found: C, 70.92;
H, 4.32; N, 2.64. IR (CH2Cl2): ν(CO) 2000 (m), 1913 (s), 1901
1
3
(s) cm-1. H NMR (CDCl3, 500 MHz): δ 7.76 (d, 2H, J ) 9.1
Hz, Ho-Ph,exo), 7.60 (d + t, 2H, HR-Py + Hm-phenylene), 7.47 (d,
1H, 3J ) 9.8 Hz, Ho-Ph,endo), 7.34 (m, 5H, 2Hm-Ph,exo
+
2Ho-phenylene + Hm-phenylene), 7.21 (t, 1H, 3J ) 9.2 Hz, Hp-Ph-exo),
7.12 (d, 1H, 3J ) 9.8 Hz, Hγ-Py), 6.84 (t, 1H, 3J ) 9.5 Hz,
3
Hm-Ph,endo), 6.59 (m, 2H, Hp-Ph,endo + Hâ-Py), 6.48 (t, 1H, J )
9.3 Hz, Hm-Ph,endo), 6.18 (d, 1H, 3J ) 8.7 Hz, Ho-Ph,endo), 2.18 (s,
3H, Me). 13C NMR (CDCl3): δ 231.7 (CO), 221.4 (CO), 220.8
(CO), 156.8, 148.9, 148.2, 147.8, 138.7, 136.3, 134.5, 133.2,
132.1, 130.9, 129.9, 128.5, 128.1, 126.0, 125.8, 125.7, 125.4,
123.9, 123.8, 114.3, 97.3, 77.7, 17.0.
H
quinoxaline), 7.54 (m, 2H, Hquinoxaline), 7.39 (broad m, 6H,
Hm-Ph,exo+Hm-phenylene), 7.27 (broad m, 4H, Hp-Ph,exo + Ho-Ph,endo),
7.18 (broad m, 4H, Hm-phenylene + Ho-phenylene), 7.09 (d, 2H, 3J )
3
8.8 Hz, Ho-phenylene), 6.90 (t, 2H, J ) 7.2 Hz, Hm-Ph,endo), 6.65
(d, 2H, 3J ) 7.2 Hz, Ho-Ph,endo), 6.39 (t, 2H, 3J ) 6.9 Hz,
P r ep a r a tion of 3-Meth yl-2-{2′-[tr ica r bon yl(η5-flu or en -
9-yl)m a n ga n ese(I)]p h en yl}p yr id in e (2c). Conditions and
reagents for this reaction are as follows: complex 2a (400 mg,
1.24 mmol), toluene (10 mL), ebullition; 9-diazofluorene (549
mg, 2.86 mmol), toluene (5 mL), dropwise addition over 45 min;
further stirring under reflux of toluene for 45 min. Chroma-
tography with a SiO2 column packed in dry hexane and cooled
at 5 °C: 2c (7:3 hexane/acetone), bright canary yellow powder
(367 mg, 71% yield). Anal. Calcd for C28H18NMnO3: C, 71.34;
H, 3.85; N, 2.97. Found: C, 71.39; H, 3.96; N, 2.84. IR (CH2-
H
p-Ph,endo), 6.30 (t, 2H, 3J ) 7.4 Hz, Hm-Ph,endo). 1H NMR (C6D6,
293 K): δ 7.87 (d, 4H), 7.54 (m, 4H), 7.49 (d, 2H), 7.23 (t, 4H),
7.16 (m, 2H), 7.06 (t, 4H), 6.83 (t, 2H), 6.66 (t, 4H), 6.60 (m,
2H), 6.35 (t, 2H), 6.13 (t, 2H). 13C NMR (CDCl3, 273K): δ 230.3
(CO), 220.9 (CO), 219.8 (CO), 146.2, 146.1, 139.4, 134.9, 133.4,
133.2, 131.9, 131.6, 131.4, 128.7, 127.6, 126.3, 125.4, 124.9,
124.6, 124.1, 115.6, 86.9, 76.2. MS (FAB+): m/Hz 890 [M]+,
806 [M - 3CO]+, 778 [M - 4CO]+, 722 [M - 6CO]+.
Syn t h esis of 2,3-Di{2′-[t r ica r b on yl(η5-flu or en -9-yl)-
m a n ga n ese(I)]p h en yl}qu in oxa lin e (3d ). A solution of 9-di-
azofluorene (500 mg, 2.6 mmol) in toluene (5 mL) was added
to a boiling solution of 3b (500 mg, 0.81 mmol) in toluene over
30 min. The color of the medium progressively changed from
deep purple to orange-yellow. The solution was further stirred
for 30 min and subsequently cooled to room temperature. The
solvent was evaporated under reduced pressure and the crude
residue dissolved in CH2Cl2. Silica gel was added to the
resulting solution and the solvent evaporated under reduced
pressure. The coated silica gel was loaded on the top of a SiO2
column packed in hexane. The first orange fraction was eluted
with a 1:4 CH2Cl2/hexane mixture and assigned to unreacted
amounts of 9-diazofluorene. A yellow band containing 3d was
eluted with a 7:3 CH2Cl2/hexane mixture. Evaporation of the
solvent afforded compound 3d as a canary yellow powder (570
mg, 79% yield). Crystals suitable for X-ray diffraction analysis
were obtained at -20 °C by the diffusion method in a narrow
glass tube containing a concentrated CH2Cl2 solution of 3d
(lower layer) and pure heptane (upper layer). Anal. Calcd for
1
Cl2): ν(CO) 2076 (m), 1933 (s) cm-1. H NMR (CDCl3): δ 8.32
3
3
3
(d, 1H, J ) 7.8 Hz), 8.12 (d, 1H, J ) 4.2 Hz), 7.96 (d, 2H, J
3
3
) 8.3 Hz), 7.70 (t, 1H, J ) 7.1 Hz), 7.60 (t, 1H, J ) 7.4 Hz),
3
3
7.52 (d, 1H, J ) 7.1 Hz), 7.31 (d, 1H, J ) 8.3 Hz), 7.08 (m,
4H), 6.96 (d, 1H, J ) 7.6 Hz), 6.75 (m, 1H), 1.57 (s, 3H). 13C
3
NMR (CDCl3, 100 MHz, 263 K): δ 225.2 (3CO), 157.9, 146.4,
141.9, 137.3, 135.3, 131.4, 131.1, 130.5, 128.8, 128.5, 127.8,
126.3, 125.5 (2C), 124.8, 124.4, 123.5, 123.1, 121.8, 107.5,
105.5, 94.5, 91.0, 83.9, 19.1.
P r ep a r a t ion of [2,3-(Dip h en yl-KC2′,KC2′′]q u in oxa lin e-
KN1,KN2)bis(tetr a ca r bon ylm a n ga n ese(I)) (3b). A solution
of 3a (2 g, 7 mmol) and (PhCH2)Mn(CO)5 (4 g, 14 mmol) in
heptane (30 mL) was brought to reflux and stirred for 20 h.
The resulting deep purple-red solution was then cooled to room
temperature and the solvent evaporated under reduced pres-
sure. The crude solid mixture was dissolved in CH2Cl2, silica
gel was added, and the solvent was evacuated under reduced
pressure. The resulting coated silica gel was loaded on the top
of a SiO2 column packed in dry hexane. A deep purple band
containing compound 3a was eluted with a 1:1 CH2Cl2/hexane
mixture. Removal of the solvents under reduced pressure
afforded a purple powder (3 g, 63% yield) that was recrystal-
lized from a mixture of CH2Cl2 and hexane. Anal. Calcd for
C
52H28N2O6Mn2: C, 70.44; H, 3.18; N, 3.16. Found: C, 70.60;
H, 3.25; N, 3.21. High-resolution MS (FAB+): calcd for
C
52H29N2O6Mn2 (MH+) 887.078 655, found 887.078 307. IR
(CH2Cl2): ν(CO) 2015 (m), 1937 (s) cm-1. H NMR (C6D6): δ
8.01 (d, 2H), 7.90 (m, 2H, Hquinoxaline), 7.61 (d, 2H), 7.49 (d, 2H),
7.25 (m, 2H, Hquinoxaline), 7.09 (d, 2H), 6.86-6.72 (m, 6H), 6.43
1
C
28H12N2O8Mn2: C, 54.75; H, 1.97; N, 4.56. Found: C, 54.87;
H, 1.79; N, 4.53. IR (CH2Cl2): ν(CO) 2076 (m), 1999 (s), 1981

Polynuclear Organometallics Helices
Organometallics, Vol. 21, No. 17, 2002 3535
1
(t, 2H), 6.35 (d, 2H), 6.25 (t, 2H), 6.19 (d, 2H), 5.75 (t, 2H). H
NMR (CDCl3, 283 K): δ 8.13 (d, 2H, 3J ) 7.5 Hz, Hphenylene),
8.00 (d, 2H, 3J ) 8.6 Hz, Hfluorenyl), 7.96 (m, 2H, Hquinoxaline),
7.79 (d, 2H, 3J ) 7.3 Hz, Hfluorenyl), 7.74 (m, 2H, Hquinoxaline),
7.25-7.19 (m, 4H, Hphenylene), 7.10 (d, 2H, 3J ) 7.8 Hz, Hphenylene),
mixture of 5b and 5c was eluted with pure CH2Cl2. The
corresponding solution was stripped of solvents under reduced
pressure and submitted to a second chromatography on SiO2
(15 µm) at 5 °C. Complex 5c was first eluted with a 1:2 mixture
of n-hexane and CH2Cl2 (109 mg, 20%). Complex 5b was
recovered by elution with pure CH2Cl2 (70 mg, 13%). Data for
complex 5b are as follows. High-resolution MS (FAB+): calcd
for C31H18NO652Cr187Re 739.009 687, found 739.010 585. IR
(CH2Cl2): ν(CO) 2022, 1976, 1928, 1901 cm-1. 1H NMR (C3D6O,
500 MHz): δ 8.74 (d, 1H, 3J ) 5.0 Hz), 8.33 (d, 1H, 3J ) 7.8
3
3
7.06 (t, 2H, J ) 7.5 Hz, Hfluorenyl), 6.93 (dd, 2H, J ) 6.6 Hz,
3J ) 8.2 Hz, Hfluorenyl), 6.43 (t, 2H, J ) 7.5, Hfluorenyl), 6.14 (d,
3
3
3
3
2H, J ) 8.9 Hz, Hfluorenyl), 6.05 (dd, 2H, J ) 6.6 Hz, J ) 8.4
Hz, Hfluorenyl), 5.86 (d, 2H, 3J ) 7.8 Hz, Hfluorenyl). 13C NMR
(CDCl3, 283 K): δ 224.9 (3CO), 153.7, 141.1, 138.0, 133.6,
132.6, 130.3, 129.9, 129.5, 128.6, 128.5, 126.7, 125.7, 125.3,
125.1, 124.6, 124.0, 123.4, 122.5, 108.1, 102.5, 96.6, 90.5, 83.3.
MS (FAB+): m/Hz 887 [MH]+, 802 [M - 3CO]+, 746 [MH -
5CO]+, 718 [M - 6CO]+, 663 [M - 6CO - Mn]+, 608 [M -
6CO - 2Mn]+.
3
3
Hz), 7.99 (d, 1H, J ) 8.0 Hz), 7.81 (d, 1H, J ) 7.5 Hz), 7.74
3
3
3
(d, 1H, J ) 7.7 Hz), 7.62 (t, 1H, J ) 6.8 Hz), 7.37 (t, 1H, J
3
3
) 7.6 Hz), 7.07 (t, 1H, J ) 7.2 Hz), 6.98 (t, 1H, J ) 7.1 Hz),
6.67 (t, 1H, 3J ) 7.7 Hz), 6.32 (d, 1H, 3J ) 6.6 Hz), 6.29 (d,
3
3
3
1H, J ) 6.6 Hz), 6.04 (t, 1H, J ) 6.4 Hz), 5.82 (d, 1H, J )
8.3 Hz), 5.69 (t, 1H, 3J ) 6.4 Hz), 3.12 (s, 3H). 13C NMR (C3D6O,
125 MHz): δ 234.7 (CO), 198 (CO), 197.5 (CO), 193.0 (CO),
158.5, 152.8, 150.1, 145.7, 145.6, 136.8, 135.0, 134.9, 126.7,
126.6, 125.5, 123.7, 123.1, 123.0, 122.6, 122.5, 120.1, 119.1,
103.2, 102.2, 96.0, 91.0, 90.2, 61.2, 24.0. Data for complex 5c
are as follows. Anal. Calcd for C32H18NO7ReCr‚2/3CH2Cl2:
C, 47.66; H, 2.37; 1.70. Found: C, 47.53; H, 2.22; N, 1.73.
High-resolution MS (FAB+): calcd for C32H18NO752Cr187Re
767.004 602, found 767.004 281. IR (CH2Cl2): ν(CO) 2094 (w),
P r ep a r a tion of P oly([2,3-d i{2′-[tr ica r bon yl(η5-flu or en -
9-yl)m a n ga n ese(I)]p h en yl}q u in oxa lin e)silver (I)]t et r a -
flu or obor a te) (3e). A stoichiometric mixture of complex 3d
and AgBF4 in dry acetone was boiled for 10 min until the color
changed from yellow to red. The solution was then filtered
through Celite and the solvent evaporated. The crude mixture
was then recrystallized from a mixture of MeOH, CH2Cl2, and
hexane and the red microcrystalline powder washed thrice
with 20 mL of dry n-hexane. Crystals suitable for X-ray dif-
fraction analysis were obtained by the slow diffusion at -20
°C of a concentrated solution of the former red crystals in a
1:1 MeOH/tetrahydrofuran mixture (lower layer) into an upper
layer of dry heptane. Anal. Calcd for C52H28Mn2N2O6AgBF4‚CH2-
Cl2‚CH3OH: C, 54.13; H, 2.86; N, 2.34. Found: C, 54.11, H,
2.70; N, 2.34.
1
1997 (s), 1963 (vs), 1936 (s), 1896 (s) cm-1. H NMR (CDCl3,
500 MHz): δ 8.87 (d, 1H, 3J ) 5.0 Hz), 8.11 (d, 1H, 3J ) 7.3
3
3
Hz), 7.94 (d, 1H, J ) 7.7 Hz), 7.87 (m, 2H), 7.43 (t, 1H, J )
3
3
7.5 Hz), 7.30 (m, 1H), 7.20 (t, 1H, J ) 7.3 Hz), 7.10 (t, 1H, J
3
3
) 7.2 Hz), 6.82 (t, 1H, J ) 7.7 Hz), 6.20 (d, 1H, J ) 5.7 Hz),
5.86 (d, 1H, 3J ) 8.0 Hz), 5.69 (t, 2H, 3J ) 6.0 Hz), 5.32 (t, 1H,
3J ) 6.4 Hz), 3.10 (s, 3H). 13C NMR (CDCl3, 125 MHz): δ 232.5
(CO), 189.6 (CO), 187.9 (CO), 187.3 (CO), 187.1 (CO), 159.2,
156.4, 153.9, 152.6, 145.1, 135.7, 134.5, 134.4, 125.9, 125.8,
125.7, 125.5, 123.9, 123.6, 123.0, 120.6, 120.5, 119.5, 100.8,
99.6, 93.5, 88.9, 87.7, 50.6, 24.8.
Syn t h esis of 2-{2′-[Tr ica r b on yl(η5-flu or en -9-yl)m a n -
ga n ese(I)]p h en yl}a za b en zo-6,6-d im et h ylb icyclo[3.1.1]-
h ep ta n e (4b). Conditions and reagents for this reaction are
as follows: complex 4a (230 mg, 0.55 mmol), n-hexane/toluene
(10:1, 11 mL), ebullition; 9-diazofluorene (212 mg, 1.10 mmol),
toluene (2.5 mL), dropwise addition over 30 min; further
stirring for 3 h. Flash chromatography on SiO2 at 6 °C: 4b
(n-hexane/acetone, 1:1), light yellow-orange powder (260 mg,
0.47 mmol, 85% yield). [R]D(CH2Cl2, 20 °C) ) -33 ( 1° dm-1
g-1 mL (c ) 3.05 mM). Anal. Calcd for C34H26NO3Mn: C, 74.04;
H, 4.75; N, 2.54. Found: C, 73.88; H, 4.90; N, 2.34. High-resolu-
tion MS (FAB+): calcd for C34H27NO3Mn (MH+) 552.137 168,
Syn th esis of 2-[Tr icar bon yl(η5-flu or en -9-yl)m an gan ese]-
a cetop h en on e (6b). Conditions and reagents for this reaction
are as follows: complex 6a (344 mg, 1.20 mmol), n-hexane/
toluene (1:1, 15 mL), ebullition; 9-diazofluorene (461 mg, 2.40
mmol), toluene (5 mL), dropwise addition for 45 min. Flash
chromatography with a SiO2 column packed in n-hexane at 5
°C: 6b (3:2 CH2Cl2/acetone), yellow light cotton-like solid (0.41
g, 0.98 mmol, 82% yield). Anal. Calcd for C24H15O4Mn: C, 68.26;
H, 3.58. Found: C, 67.51; H, 3.75. High-resolution MS (EI):
calcd for C24H15O4Mn m/Hz 422.0351, found 422.0350. IR (CH2-
Cl2): ν(CO) 2017 (s), 1934 (vs); ν(CdO) 1721 (w). 1H NMR
found 552.137 140 amu. IR (CH2Cl2): ν(CO) 2014, 1931 cm-1
1H NMR (CDCl3, 20 °C, 500 MHz): δ 8.30 (d, 1H, 3J ) 7.1
.
3
3
Hz), 7.98 (d, 2H, J ) 8.7 Hz), 7.71 (d, 1H, J ) 7.6 Hz), 7.66
(m, 1H), 7.59 (t, 1H, 3J ) 7.5 Hz), 7.29 (m, 1H), 7.24 (d, 1H, 3J
3
3
(CDCl3, 500 MHz): δ 8.30 (d, 1H, J ) 7.5 Hz), 8.15 (m, 2H),
) 8.7 Hz), 7.12 (m, 3H), 7.03 (t, 1H, J ) 7.4 Hz), 6.61 (d, 1H,
7.79 (t, 1H, 3J ) 7.5 Hz), 7.73 (d, 1H, 3J ) 7.7 Hz), 7.59 (t, 1H,
3J ) 7.7 Hz), 7.29 (m, 6H), 1.84 (s, 3H). 13C NMR (CDCl3, 125
MHz): δ 224.9 (CO), 201.9, 142.4, 136.9, 132.1, 130.5, 128.8,
128.7, 128.4 (2C), 125.3 (2C), 125.0 (2C), 123.2 (2C), 107.9,
93.1, 84.1, 29.2. MS (EI): m/Hz 422 [M]+, 394 [M - CO]+, 366
[M - 2CO]+, 338 [M - 3CO]+, 333 [M - 3CO - Mn]+, 289 [M
- 3CO - Mn - HC(O)CH3]+.
3J ) 7.5 Hz), 6.43 (d, 1H, J ) 7.7 Hz), 2.50 (m, 3H), 2.13 (m,
3
1H), 1.25 (m, 4H), 0.88 (m, 1H), 0.20 (s, 3H). 13C NMR (CDCl3,
125 MHz): δ 225.4 (CO), 155.9, 155.6, 143.1, 139.5, 136.0,
132.3, 130.6, 129.9, 128.8 (2C), 127.6, 127.4, 124.9, 124.6, 124.4
(2C), 124.2, 123.8, 120.1, 108.0, 107.5, 93.3, 92.5, 85.3, 45.9,
40.0, 39.2, 36.0, 31.9, 26.0, 21.1. MS (FAB+): m/Hz 552.0 [M]+,
467.1 [M - 3CO - H]+, 412.1 [M - Mn(CO)3 - H]+.
R ea ct ion of 5a w it h 9-Dia zoflu or en e: F or m a t ion of
2-[Tr icar bon yl{η6-2′-[tr icar bon yl(η5-flu or en -9-yl)r h en iu m -
(I)]ph en yl}ch r om iu m (0)]-3-m eth ylpyr idin e (5b)an d Tetr a-
ca r b on yl[2-{η6-2′-[t r ica r b on yl(9′′-η:flu or e n -9′′-yl-KC9)-
p h en yl}ch r om iu m (0)]-3-m et h ylp yr id in e-KN]r h en iu m -
(I) (5c). To a boiling solution of complex 5a (472 mg, 0.71
mmol) in n-heptane/toluene (3:1) (20 mL) was added a solution
of 9-diazofluorene (272 mg, 1.42 mmol) in toluene (6 mL) over
a total period of 4 h. The reaction mixture was further stirred
and boiled for 4 h and cooled to room temperature. The
solvents were removed under reduced pressure and the crude
mixture dissolved in CH2Cl2. Silica gel was added to the
resulting solution and the solvent removed under vacuum. The
coated silica gel was loaded on the top of a SiO2 column packed
in n-hexane at 5 °C. The orange band containing the unreacted
starting complex 5a was recovered with a 1:2 mixture of
n-hexane and CH2Cl2 (66.7 mg). A red band containing a
Ack n ow led gm en t. We gratefully acknowledge the
support provided by the Centre National de la Recher-
che Scientifique and the Deutsche Forschungsgemein-
schaft. Z.R. particularly thanks the CNRS for the
financial support provided through an associate-re-
searcher fellowship. We also thank Maxime Bernard
and Professor J ean-J acques Andre´ from the Institute
Charles Sadron for their contribution in the acquisition
and analysis of the ESR data.
Su p p or tin g In for m a tion Ava ila ble: Listings of crystal-
lographic and structural data for compounds 1b,c, 2b, 3c-e,
and 5a ,c; these data are also available as CIF files. This
material is available free of charge via the Internet at
http://pubs.acs.org.
OM020116Z