Synthesis of multi-1,10-phenanthroline ligands with 1,3-phenylene linkers and their lithium complexes

Article abstract of DOI:10.1002/chem.200401264

The synthesis of two multisite ligands containing four and five 1,10-phenanthroline (phen) chelates in line, respectively, is presented. The connectors are 1,3-phenylene linkers. The two ligands were prepared following multistep procedures, the two key re

Full text of DOI:10.1002/chem.200401264

Synthesis of Multi-1,10-phenanthroline Ligands with 1,3-Phenylene Linkers
and Their Lithium Complexes
Christiane Dietrich-Buchecker, Benoît Colasson, Damien Jouvenot, and
Jean-Pierre Sauvage*[a]
Abstract: The synthesis of two multi-
site ligands containing four and five
1,10-phenanthroline (phen) chelates in
line, respectively, is presented. The
connectors are 1,3-phenylene linkers.
The two ligands were prepared follow-
ing multistep procedures, the two key
reactions being the Suzuki coupling re-
action between aromatic nuclei and the
nucleophilic addition of aryllithium de-
rivatives onto a phen fragment. The co-
ordination chemistry of both ligands
with Li+ ions was very clean and selec-
tive, whereas their reaction with cop-
per(i) led to intractable mixtures of in-
soluble complexes. The tetraphen and
the pentaphen compounds afforded
almost quantitatively the four- and
five-lithium double-stranded helical
complexes, respectively. The helical
systems are probably highly wound, as
indicated by NMR measurements. The
pronounced strain of the 5-Li+ com-
plex is reflected by the easy loss of a
lithium cation, as shown by electro-
spray mass spectrometry.
Keywords: chelates · coordination
chemistry
·
copper
·
helical
complexes · lithium · N ligands
Introduction
multiply interlocking [2]catenanes and knots, as depicted in
Figure 1.[9]
Transition metals have been used as three-dimensional tem-
plates with particular efficiency in the preparation of various
interlocking or knotted topologies. The key feature of this
approach is the ability of the metal centers to gather various
coordinating organic fragments and predispose them to a ge-
ometry which is very favorable for the formation of cate-
nanes, rotaxanes and knots.
Doubly interlocking catenanes have indeed been made[10]
following the strategy shown in Figure 1.[9] The Li+ ion was
Since the synthesis of the first [2]catenane built around a
copper(i) center,[1,2] many other novel topologies have been
synthesized in the course of the last two decades.[3] Recent
examples include catenanes and rotaxanes constructed
around an octahedral center[4] and the Borromean rings
built under thermodynamic control around six zinc cations.[5]
Multinuclear double-stranded helical complexes have
been synthesized by various groups[6,7] and triple-stranded
helices have also been reported.[8] Double-stranded helices
represent an interesting family of accessible precursors to
[a] Dr. C. Dietrich-Buchecker, Dr. B. Colasson, Dr. D. Jouvenot,
Dr. J.-P. Sauvage
Figure 1. Double-stranded helical complexes (“helicates”, as defined by
Lehn and co-workers[7]), which are topologically planar systems, can lead
to knots and “links” (i.e., catenanes) through appropriate connections be-
tween the ends of the strands. The number of metal centers used to
gather and orient the two strands will determine the number of crossings
and thus the topology of the final object.
Laboratoire de Chimie Organo-MinØrale
UMR 7513 du CNRS, Institut Le Bel, UniversitØ Louis Pasteur
4 rue Blaise Pascal, 67000 Strasbourg Cedex (France)
Fax : (+33)390-241-368
E-mail: sauvage@chimie.u-strasbg.fr
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DOI: 10.1002/chem.200401264
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FULL PAPER
used as the gathering metal which forms relatively labile
complexes with 1,10-phenanthroline (phen) derivatives, thus
allowing the three-metal double-stranded helical precursor
to be prepared under thermodynamic control.
Preparation of 2-bromo-9-(p-anisyl)phenanthroline (6): Bro-
mophenanthroline 6 was prepared in two steps starting from
2-chlorophenanthroline (3) which could be obtained on a
large scale (20 g) by following a previously reported proce-
dure.[13] p-Lithioanisole (4), obtained from p-bromoanisole
by an interconversion reaction with two equivalents of tert-
butyllithium, was added to 3 at a low temperature (3–48C)
without altering the position of the chloride. After hydroly-
Since the pentafoil knot 51 (see reference [11] for nomen-
2
clature) and the star of David 61 (or triply interlocking
[2]catenane) are particularly attractive, we decided to apply
the strategy shown in Figure 1 to the preparation of these
species. To achieve this it was
necessary to make multi-phen
ligands in which each phen che-
late is connected to its neigh-
bor(s) through 1,3-phenylene
linkers. From previous work,[12]
we know that this is an appro-
priate connector and, used in
conjunction with 2- and 9-sub-
stituted phen, it appeared very
likely that the desired helical
complexes would form once the
ligands have been made and
treated with Li+ or CuI.
The two target ligands are
represented in Scheme 1. In this
report we describe the synthesis
of these tetra- and pentaphen
ligands as well as the formation
of their helical complexes with
Li+ ions.
Scheme 1. Retrosynthetic analysis of the target compounds 1 and 2; compound 1 can be constructed by assem-
bling two mono-1,10-phenanthroline fragments to a central two-phen building block whereas the synthesis of
compound 2 involves a central mono-phen and two peripheral two-phen fragments. The thick oblique lines in-
dicate which bonds will be formed in the condensation reaction between the various building blocks.
Results and Discussion
A retrosynthetic analysis of the
preparation of 1 and 2 depicts
how both multichelates can be
synthesized from judicious com-
bination of several small func-
tionalized
building
blocks
(Scheme 1).
According to Scheme 1, both
the tetraphenanthroline and the
pentaphenanthroline should be
obtained by Suzuki cross-cou-
pling reactions between mono-
phenanthrolines or diphenan-
throlines that have either a bor-
onic or a reactive halide (bro-
mide or iodide) functionality.
Synthesis of the tetraphenan-
throline 1: After several at-
tempts the most convenient
strategy for the synthesis of the
tetraphenanthroline appeared
to be the one described in
Scheme 2.
Scheme 2. Strategy for the synthesis of an end-functionalized tetraphenanthroline by a double Suzuki cross-
coupling reaction.
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J.-P. Sauvage et al.
sis, rearomatization with MnO2, and column chromatogra-
phy over silica gel, 2-chloro-9-(p-anisyl)phenanthroline (5)
was obtained in 62% yield (Scheme 3).[14,15] Subsequent ex-
Synthesis of the diboronic diphenanthroline 12: The diboron-
ic ester 12 was obtained in several steps as depicted in
Scheme 4. In the first step the two phenanthrolines were
connected to a 1,3-phenylene bridge by reacting 1,3-dilithio-
benzene with two equivalents of 1,10-phenanthroline dis-
solved in THF at room temperature.[12] Diphenanthroline 8,
isolated in 40% yield after column chromatography over
silica gel, was subsequently treated with 1-lithio-3-trimethyl-
silylbenzene (9) at 5–78C for 3 h.[17] After hydrolysis and
rearomatization with MnO2, pure diphenanthroline 10 was
obtained in 58% yield after column chromatography over
silica gel. The third step, namely the exchange of the trime-
thylsilyl groups with iodine, involved the addition of a solu-
tion of ICl in CH2Cl2 to a degassed solution of 10 in CH2Cl2
at 08C under argon. After the addition of ICl, the solution
was allowed to warm to room temperature and then stirred
for 3 h. After extractive workup and purification of the
crude product by column chromatography over alumina, the
diiodide 11 was obtained as a colorless solid in 98% yield.
Whilst the formation of a boronic acid or ester of a sub-
strate containing one or several chelates by quenching the
corresponding lithio or magnesium intermediate with B-
(OMe)3 appeared impossible, the use of commercially avail-
able bis-neopentyl diboron in the presence of [Pd-
(dppf)Cl2]·CH2Cl2 as catalyst allowed the diester 12 to be
prepared in 58% yield.[18] In this work, this new methodolo-
gy developed by Miyaura and co-workers appeared destined
for success.
Scheme 3. Synthesis of 2-bromo-9-(p-anisyl)phenanthroline (6).
change of the chloride at the 2-position was performed by
following a modification of the procedure described in the
literature.[16] Chloride 5 and neat PBr3 (1708C) were re-
fluxed under argon for a short time (45 minutes). No major
degradation of 5 or 6 was observed despite the very harsh
reaction conditions as long as the reaction time was kept
short (here, a maximum of 45 min) and the reaction carried
out under an inert atmosphere (argon).
Bromide 6 was obtained in 81% yield after hydrolysis of
the crude product on crushed ice, neutralization, and filtra-
tion of the precipitate.
Formation of the tetraphenanthroline core (see Scheme 2):
Owing to the poor solubility of diphenanthroline 12, the
double cross-coupling reaction between 12 and two equiva-
lents of 6 could only be performed in DMF.[19] Synthesis of
the tetraphenanthroline 13 was thus easily achieved by heat-
ing a mixture of 6 and 12 (in a ratio of 2:1) dissolved in
DMF in the presence of the catalyst [Pd(PPh3)4] and K3PO4
for two days at 1008C under an argon atmosphere
(Scheme 2). After workup and column chromatography
over silica gel, tetraphenanthroline 13 was obtained as a
1
brown solid in 60% yield. Its H NMR spectrum as well as
its mass spectrum, with its large molecular ion peak found
at m/z 1156.3 [M+H]+ (calcd at 1156.3), were in full agree-
ment with the structure proposed for tetraphenanthroline 13.
Subsequent deprotection, achieved by refluxing 13 for
three hours in pyridinium hydrochloride (210–2208C), led to
[20]
the diphenol 14.
Despite such harsh conditions, diphenol
14 was nevertheless obtained as a poorly soluble brown
solid in 95% yield.
Synthesis of the diolefinic tetraphenanthroline 1: As shown in
Scheme 5, the diphenol 14 was functionalized with two ole-
finic chains derived from tetra(ethylene glycol).[21] Tetraphe-
nanthroline 1 appeared to be a good precursor with which
to achieve cyclization to the pentafoil knot by ring-closing
metathesis (RCM; see Figure 1). Incidentally, the solubility
of tetraphenanthroline 13 could be increased markedly by
the introduction of two such chains at its extremities.
Scheme 4. Multistep preparation of diboronic ester 12.
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Synthesis of Multi-phenanthroline Ligands
FULL PAPER
(CH3CN)4·PF6
dissolved
in
CH3CN to a CH2Cl2 solution of
ligand 1 under argon led only
to an intractable mixture of oli-
gomeric dark red copper(i)
complexes.
This
surprising
result can only be explained in
terms of the high stability and
the inertness of the kinetic
polynuclear copper(i) com-
plexes which precludes any self-
repair process. Indeed, no equi-
libration was observed on re-
fluxing the oligomeric copper(i)
complexes in acetonitrile for
several days. According to the
literature and from our own ex-
Scheme 5. Synthesis of diolefinic tetraphenanthroline 1.
perience, the use of lithium cat-
ions should lead to much less
The nucleophilic substitution reaction between the diphe-
nolate derived from 14 and the bromo-allyl-poly(ethylene
glycol) chain took place under classic conditions, that is, by
heating diphenol 14 dissolved in DMF in the presence of a
large excess of the bromo-allyl chain and Cs2CO3 at 658C
for one day. Column chromatography of the crude product
over silica gel afforded pure 1 in 80% yield.
stable complexes that are able to equilibrate in favor of the
thermodynamically most stable complex with a double helix
structure.[10,12,22,23] Addition, under argon, of LiPF6 dissolved
in methanol to ligand 1 dissolved in CH2Cl2 (ratio of Li+/
ligand 1 =4:2) led upon addition of a small amount of basic
Li2CO3, necessary to neutralize the residual acidity of LiPF6
(traces of HPF6), to
a single pale yellow complex
(Scheme 6).
1
Coordination properties of ligand 1: Owing to the well-
The H NMR spectrum of this latter complex exhibits a
strong chemical upfield shift for some of the protons in the
aromatic region. Interestingly the most affected protons, for
which Dd<À2 ppm, are the protons H-3’, H-3, H-8, H-a’,
and H-a, which are located very
À
known high affinity of copper(i) towards –N N- chelate-
containing ligands, we investigated the coordination chemis-
try of copper(i) with ligand 1 first.[22] Addition of Cu-
close to the crossing points of
the
double-stranded
helix
(Table 1). Previous studies of
helices and molecular knots
have shown that the signature
for such intertwined or knotted
structures was precisely
a
strong chemical upfield shift for
all the protons located in close
proximity to the crossing points.
Moreover, the high-resolution
ES-MS spectrum has a major
peak at m/2 1718.6457 for
[(1)2·4Li]4+·(2PF6)2À
(calcd
1718.6466). It is therefore clear
that the complex [(1)2·4Li]4+
·(4PF6)4À most probably has a
double-helix structure.[12,24,25]
Scheme 6. Formation of a double helix around four lithium cations.
[a]
Table 1. Chemical shifts [ppm] for 1 and [(1)2·4Li]4+·(4PF6)4À
.
H-o
H-m
H-3’
H-a’
H-b’
H-d’
8.52
H-c’
7.76
H-8
8.30
H-3
8.30
H-a
9.75
H-b
8.58
H-c
7.75
H-A
4.18
H-B
3.88
1
8.42
7.02
8.30
9.70
8.63
(1)2·4Li
6.70
À1.72
5.59
À1.43
6.20
À2.10
7.45
À2.25
6.70
À1.93
6.70
À1.82
6.94
À0.82
6.00
À2.30
6.00
À2.30
7.45
À2.30
6.70
À1.88
6.89
À0.86
3.25
À0.93
3.47
À0.41
Dd[b]
[a] Solvent: CD2Cl2 for 1, CD3CN for [(1)2·4Li]4+·(4PF6)4À. [b] Dd=d[(1)2·4Li]Àd(1).
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J.-P. Sauvage et al.
Scheme 7. Strategy and building blocks for the synthesis of a pentaphenanthroline.
Synthesis of the pentaphenanthroline 2: The strategy used
for the synthesis of pentaphenanthroline is shown in
Scheme 7.
bromine atom in intermediate compound 17 was then sub-
mitted to a second interconversion reaction with 1.3 equiva-
lents of nBuLi at 38C to afford the aromatic lithio inter-
mediate 18. TLC performed on a small aliquot withdrawn
from the reaction mixture showed that this interconversion
was complete after stirring for 2 h at 5–108C. The last step,
the addition of the solution containing 18 to a degassed so-
lution of 2-chlorophenanthroline in toluene, was also per-
formed at 2–48C. After stirring and warming to room tem-
perature, the mixture was hydrolyzed with water and rear-
omatized with MnO2. Column chromatography over silica
gel afforded pure diphenanthroline 19 in 34% yield. It
should be emphasized here that the rearomatization of 17
followed by interconversion with nBuLi and addition of 3
did not yield any trace of 19. We had previously observed
that a free chelate (phenanthro-
Synthesis of diphenanthroline 19: Starting from mono-p-ani-
sylphenanthroline 15, which can be easily prepared on a
10 g scale, diphenanthroline 19 was obtained by following
the multistep procedure depicted in Scheme 8.[15]
A diethyl ether solution of 1-lithio-3-bromobenzene (16),
prepared from 1,3-dibromobenzene by interconversion with
one equivalent of nBuLi at a low temperature (2–48C), was
added to a degassed suspension of 15 in diethyl ether also
maintained at 28C.[17] Monitoring by TLC allowed us to see
that after 2 h of stirring at 2–48C, 15 had been entirely
transformed into the disubstituted phenanthroline 17. The
line or terpyridine) inhibits the
interconversion step. As a con-
sequence, it is necessary to use
the intermediate 17, in which
the coordinating site is occu-
pied by a Li+ ion, immediately.
Repetition of this multistep
process clearly showed that its
success was strongly related to
the temperature and reaction
time used in each sequence in
order to preserve the potential-
ly reactive sites that are the
bromine in compound 16 and
17 and the chlorine in 19.
Preparation of bromide 20:
Several attempts to perform the
cross-coupling reaction between
chloride 19 and the diboronic
ester 23 or acid 24 (see later)
Scheme 8. Multistep synthesis of diphenanthroline 19.
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Synthesis of Multi-phenanthroline Ligands
FULL PAPER
following the procedure developed by Fu and co-workers
failed owing to the very low solubility of the diphenanthro-
line 19 in dioxane or THF.[26] Therefore it appeared necessa-
ry to exchange the chlorine for the more reactive bromine
atom. Bromide 20 was obtained in 65% yield after stirring
the chloride 19 for 40 min in refluxing neat PBr3
(Scheme 8).[16]
Preparation of the diboronic ester 23: Following the method-
ology developed by Miyaura and co-workers, the diboronic
ester 23 was obtained in 90% yield by refluxing the dibro-
mide 22 with bis-pinacolatodiboron in dioxane for 12 h
in the presence of Pd(dppf)Cl2·CH2Cl2 as catalyst
(Scheme 10).[18]
The diboronic acid 24 was obtained in 99% yield by stir-
ring a solution of 23 in THF (30 mL) and 3m HCl (30 mL)
at room temperature for four days.[29]
Synthesis of the 2,9-disubstituted phenanthroline 22: The
presence of the reactive bromine atom in 1-lithio-3-bromo-
benzene (16) precludes its use in excess at room tempera-
ture, which are the classic conditions used in the direct for-
mation of a 2,9-disubstituted phenanthroline.[14,27] This dif-
ficulty was easily circumvented by performing two succes-
Synthesis of pentaphenanthroline 25: The double Suzuki
cross-coupling reaction between two bromo-diphenanthro-
lines 20 and one central diboronic phenanthroline 24 was
again performed in DMF at 1008C in the presence of K3PO4
and [Pd(PPh3)4] as catalyst over a period of two days
(Scheme 11).
sive monosubstitution reactions at
a low temperature
(Scheme 9).[15,28]
Although the coupling proce-
dure used was similar to the
one which afforded the tetra-
phenanthroline 13, workup and
isolation had to be adapted to
the special features exhibited
by the pentachelate 25. Indeed
the poor solubility of 25, relat-
ed to its strong tendency to
Scheme 9. Preparation of the 2,9-disubstituted phenanthroline 22 by two distinct monosubstitution reactions.
bind or coordinate trace
amounts of cations (Li+, Na+,
H+, K+, etc.) present in sol-
Anhydrous 1,10-phenanthroline was treated with a slight
excess of 1-lithio-3-bromobenzene (16) in diethyl ether at 2–
48C for 2 h. After hydrolysis, rearomatization with MnO2,
and purification by column chromatography over silica gel,
pure 2-(m-bromophenyl)phenanthroline 21 was obtained in
32% yield as a colorless solid. Subsequently, 21 was submit-
ted to a second monosubstitution reaction by 16 under the
same conditions as described above to afford the 2,9-disub-
stituded phenanthroline 22 in 24% yield. The low yields can
be explained by secondary cascade interconversions that
occur on the bromine atoms present in 21 and 22 even at 2–
48C. An attempt to reduce the occurrence of these secon-
dary interconversion reactions by lowering the temperature
to À58C was very disappointing since no reaction at all oc-
curred at this temperature. Thus it appeared that 21 and 22
can only be prepared in a very narrow range of tempera-
tures.
vents, glassware, and solid supports like silica gel or alumi-
na, prohibited the use of classic column chromatography in
the purification process.
As a result of the special features of compound 25, the
solid crude product, obtained by addition of a large amount
of water to a DMF solution and filtration of the precipitated
crude solid, was suspended in CH2Cl2 and poured onto a dry
silica gel column. All products other than 25 were eluted
with CH2Cl2 containing increasing amounts of MeOH. De-
sorption of 25 from the solid support was achieved by
taking advantage of its coordination properties, namely its
strong affinity towards lithium cations. The silica gel from
the column was poured into a beaker and recovered with a
CH2Cl2/MeOH (93:7) solution before a large excess of
LiPF6 was added under a stream of argon. After stirring for
four days, the heterogeneous mixture was filtered through a
1
sintered glass. The H NMR spectrum of the filtrate showed
that it contained both lithium complexes and protonated
ligand 25. Subsequent addition
of CF3COOH to the filtrate af-
forded fully protonated, soluble
25 in 83% yield. Complex
À
(25·5H)5+·5PF6 was fully char-
1
acterized by H NMR spectros-
copy and by its mass spectrum,
with intense peaks at m/z
1410.5
[M+H]+,
705.5
[M+2H]2+
,
470.7 [M+3H]3+
,
Scheme 10. Synthesis of diboronic ester 23 and diboronic acid 24.
and 353.3 [M+4H]4+
.
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J.-P. Sauvage et al.
Synthesis of the diolefinic penta-
phenanthroline 2:The dipheno-
late of 26 formed in DMF at
658C in the presence of Cs2CO3
was treated with an excess of
the bromo-allyl-poly(ethylene
glycol) chain derived from pen-
ta(ethylene glycol).[21] Owing to
the coordination properties ex-
pected of a pentachelate like 2,
use of column chromatography
in the purification process was
avoided. The solid crude prod-
uct was merely washed first
with diethyl ether in order to
remove excess of the bromo-
allyl chain and thereafter with
water to eliminate Cs2CO3. This
very simple purification proce-
dure afforded the very soluble
diolefinic pentaphenanthroline
2 in 62% yield (Scheme 12).
Scheme 11. Double cross-coupling reaction affording pentaphenanthroline 25.
Coordination properties of 2:
Lithium complex [(2)2·5Li]5+
·
(5PF6)5À: Pentachelate 2 exhib-
its the same, although en-
hanced, coordination properties
as tetrachelate 1. Like 1, ligand
2 forms only a mixture of oligo-
meric complexes in the pres-
ence of copper(i) whereas it
forms, in the presence of LiPF6,
a single, well-defined complex
[(2)2·5Li]5+·(5PF6)5À
(Scheme 13).
1
Its H NMR spectrum, char-
acterized by large chemical up-
field shifts for most of the pro-
tons of the aromatic region (see
Table 2), is in good agreement
Scheme 12. Synthesis of diolefinic pentaphenanthroline 2 with the numbering scheme.
Synthesis of the diphenol pentaphenanthroline 26: Deprotec-
tion of the methoxy groups of 25 was performed in refluxing
pyridinium hydrochloride following the procedure already
used for the preparation of diphenol 14.[20] Diphenol 26 was
obtained in 93% yield as an ochre solid almost insoluble in
all solvents but DMF (Scheme 11).
with a double-helix structure. Its mass spectrum confirms
the ratio of two molecules of ligand 2 to five Li+ ions with
the peaks for m/2 observed at 2136.8278 (calcd 2137.0241)
for [(2)2·5Li]5+·(3PF6)3À, m/3 at 1376.1988 (calcd 1376.3613)
for [(2)2·5Li]5+·(2PF6)2À, m/4 at 995.9139 (calcd 996.0299) for
[(2)2·5Li]5+·(PF6)À, m/5 at 767.7443 (calcd 767.8311) for
[a]
Table 2. Chemical shifts [ppm] for 2, [(2)2·5Li]5+·(5PF6)5À and [(2)2·3Li·2Cu]5+·(5PF6)5À
.
H-o
H-m
H-3,8
H-3’
H-8’
H-3’’
H-a
H-a’
H-4,7
H-4’
8.10
7.47
À0.63
7.46
H-7’
8.36
7.50
À0.86
7.48
H-4’’
H-7’’
H-A
4.17
3.32
À0.85
3.34
H-B
3.87
3.60
À0.27
3.55
2
8.41
7.03
8.29
5.90
À2.39
5.90
0
8.27
8.36
8.30
6.05
9.78
9.69
7.64
8.05
7.37
8.04
7.53
8.21
8.14
(2)2·5Li
6.65
À1.76
6.75
5.56
À1.47
5.52
À0.04
5.94
À2.33
6.11
6.10
À2.26
5.95
À0.15
7.24
À2.54
7.23
À0.01
D1d[b]
À2.25
À2.05
À0.68
À0.51
À0.07
(2)2·2Cu·3Li
D2d[b]
6.04
8.33
7.38
7.52
8.16
0.10
0.17
À0.01
0.69
0.01
À0.01
À0.02
À0.01
0.02
0.02
À0.05
[a] Measured in CD2Cl2. [b] D1d=d[(2)2·5Li]Àd(2); D2d=d[(2)2·2Cu·3Li]Àd[(2)2·5Li].
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Synthesis of Multi-phenanthroline Ligands
FULL PAPER
served chemical shifts d occur at the extremities of the com-
plex and reflect the differences in size of the Cu+ and Li+
cations. In the ES-MS spectrum, along with the m/z peaks
expected for complex [(2)2·3Li·2Cu]5+·(5PF6)5À, peaks
appear that correspond to the complex [(2)2·2Li·2Cu]4+
·(4PF6)4À in which the strain has been relieved by expulsion
of the central lithium cation.
Scheme 13. Formation of complexes [(2)2·5Li]5+·(5PF6)5À and [(2)2·4Li]4+
·(4PF6)4À
.
Conclusions
Two new multi-phenanthroline ligands 1 and 2 have been
synthesized. After preliminary work aimed at selecting the
best synthetic strategy, the following retrosynthetic ap-
proaches were defined: the tetraphen compound was con-
structed from a central phen-1,3-phenylene-phen motif and
two peripheral 2,9-diaryl-phen building blocks. In contrast,
the synthetic strategy for the pentaphen molecule involves
the coupling of a central 2,9-disubsituted-phen to two
diphen fragments.
[(2)2·5Li]5+. The occurrence of a series of peaks correspond-
ing to the m/z for the complex [(2)2·4Li]4+·(4PF6)4À strongly
suggests the presence of a highly wound structure in which
the lithium cation in the central cavity could very easily be
expelled under the conditions of mass spectrometry. No evi-
dence for the presence of [(2)2·4Li]4+·(4PF6)4À in solution
1
could be found from careful analysis of the H NMR spec-
trum. Nevertheless, if such a species exists, the symmetrical
spectrum (in this case, the superposition of the spectra of
[(2)2·5Li]5+·(5PF6)5À and [(2)2·4Li]4+·(4PF6)4À) tends to indi-
cate that the cavity must be in the central position of the
double helix.
Two double-helical structures based on 1 or 2 were ob-
tained which display similar properties. Both helices are as-
sembled around lithium cations and are very strained, as
1
proved by H NMR and mass spectrometry studies.
1H NMR studies confirm the presence of a double-helix
structure which is very strained in its central part. Indeed,
the difference in the chemical shifts (Dd) increases on going
from the centre of the double helix to its extremities: Dd=
À2.39 (H-3,8), À2.33 (H-3’), À2.26 (H-8’), À2.25 (H-3’’),
À2.54 (H-a), and À2.05 ppm (H-a’).
Cyclization reactions under ring-closing metathesis condi-
tions were attempted with the tetraphen and pentaphen lith-
ium complexes attached to olefinic fragments. Unfortunate-
ly, the desired topologies (pentafoil knot 51 and the star of
2
David 61 , respectively) could not be isolated as yet.
Metal-exchange reactions conducted on the lithium com-
plex of the pentaphen ligand showed that selective replace-
ment of the terminal lithium cations by copper(i) takes
place, the kinetic inertness of the more central Li+ ions pre-
venting them from being substituted for CuI. A Cu–Li–Li–
Li–Cu complex was thus obtained. These helical complexes
are likely to be electronically or electrostatically highly cou-
pled, in analogy with previous observations of the two-
copper system. This is partly due to the conjugated charac-
ter of the ligands. This feature, combined with the length of
the helical complexes, makes them particularly promising
compounds for long-range electron transfer. Interestingly,
the five-Li+ compound contains two sets of 16 six-mem-
bered aromatic groups attached to one another and the
overall length of the helical complex has been estimated to
be 28 Š.
Heteronuclear lithium-copper(i) complex [(2)2·3Li·2Cu]5+
·(5PF6)5À: Although obtained easily and in good yield
(76%), the lithium complex [(2)2·5Li]5+·(5PF6)5À is not very
stable. In particular it completely decomposes in the pres-
ence of polar solvents containing oxygen, for example, in
DMF. Addition of two equivalents of the copper(i) salt Cu-
(CH3CN)4·PF6 afforded in quantitative yield a dark red com-
plex [(2)2·3Li·2Cu]5+·(5PF6)5À whose helical structure is
locked by a copper(i) cation located at each end of the com-
1
plex (Scheme 14). Its H NMR spectrum is characterized by
Experimental Section
General: All chemicals were of the best commercially available grade
and used without further purification. Dry solvents were distilled from
suitable desiccants (Et2O, THF, and dioxane from Na/benzophenone).
Column chromatography was performed with silica gel 60 (Merck 9385,
230–400 mesh) or aluminium oxide 90 (neutral, act. II–III, Merck 1097).
1H and 13C NMR spectra were recorded with a Bruker WP 200 SY
(200 MHz), AVANCE 300 (300 MHz), AVANCE 400 (400 MHz), or
AVANCE 500 (500 MHz) spectrometer using deuteriated solvent as the
lock. The spectra were collected at 258C and the chemical shifts were ref-
Scheme 14. Heteronuclear complexes [(2)2·3Li·2Cu]5+·(5PF6)5À and
[(2)2·2Li·2Cu]4+·(4PF6)4À
.
chemical shifts similar to those of the lithium complex
[(2)2·5Li]5+·(5PF6)5À with Dd close to zero for most of the
protons (see Table 2). The only small variations in the ob-
Chem. Eur. J. 2005, 11, 4374 – 4386
www.chemeurj.org
ꢀ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
4381

J.-P. Sauvage et al.
erenced to residual solvent protons as internal standards (1H: CDCl3
7.27 ppm, [D6]DMSO 2.50 ppm, CD2Cl2 5.32 ppm, CD3CN 1.94 ppm; 13C:
CD3Cl 77 ppm, CD2Cl2 53.7 ppm. Mass spectra were obtained with a VG
ZAB-HF spectrometer (FAB) and a VG-BIOQ triple quadrupole in pos-
itive mode (ES-MS).
with water at 08C. The mixture was evaporated to dryness and the
orange residue was taken up in CH2Cl2/H2O, the organic layer decanted
and rearomatized with MnO2 (27 g). An equivalent amount of MgSO4
was added to the stirred mixture. After stirring for 1 h, the MgSO4/MnO2
slurry was filtered through a sintered glass and the solvent evaporated to
dryness to afford 6.05 g of a crude mixture which was submitted to
column chromatography over alumina (eluent: CH2Cl2/hexane, 80:20). A
second chromatography over silica gel (eluent: CH2Cl2/2 to 5% MeOH)
afforded pure 8 (1.939 g, 4.46 mmol) in 40% yield as a white solid. 1H
NMR (300 MHz, CDCl3): d=9.26 (dd, J1 =4.4, J2 =1.8 Hz, 2H, H-9),
9.19 (t, J=1.7 Hz, 1H, H-a), 8.55 (dd, J1 =7.9, J2 =1.7 Hz, 2H, H-b), 8.36
(AB, J=8.4 Hz, 2H, H-3,4), 8.28 (dd, J1 =8.2, J2 =1.8 Hz, 2H, H-7), 7.83
(AB, J=8.9 Hz, 4H, H-5,6), 7.78 (d, J=7.9 Hz, 1H, H-c), 7.66 ppm (dd,
J1 =8.2, J2 =4.4 Hz, 2H, H-8); 13C NMR (75 MHz, CDCl3): d=157.51,
150.24, 145.99, 140.09, 136.92, 136.33, 129.48, 129.25, 129.14, 127.76,
127.18, 126.55, 126.27, 122.97, 122.35, 121.19 ppm; HR FAB-MS: m/z:
435.1608 [M+H]+, calcd 435.1610.
2-Chloro-9-(p-anisyl)phenanthroline (5): 2-Chlorophenanthroline 3 was
prepared in three steps from commercial 1,10-phenanthroline according
to the literature procedure,[13] whereas p-lithioanisole 4 was prepared by
interconversion of p-bromoanisole with two equivalents of tBuLi; a THF
solution (50 mL) of p-lithioanisole 4 (15 mmol) was obtained by slow ad-
dition of tBuLi (30 mmol) to a THF solution (40 mL) of p-bromoanisole
(2.806 g, 15 mmol) at À788C under argon. The lithioanisole solution was
thereafter added to a degassed suspension of 3 (2.147 g, 10 mmol) in tolu-
ene (100 mL) maintained at 3–48C. The initial pale yellow suspension of
3 turned dark red instantaneously. After addition of this lithioanisole so-
lution, the dark solution was stirred under argon at +48C for an addi-
tional 2 h. Thereafter the reaction was quenched by addition of water
(20 mL) and the resulting mixture was evaporated to dryness. The
orange-brown residue thus obtained was taken up in a mixture of CH2Cl2
and water and decanted. The aqueous layer was washed and extracted
with more CH2Cl2. The bright yellow organic phase was then rearomat-
ized by successive addition of batches of MnO2 (12 g). The rearomatiza-
tion was monitored by TLC. After the quite slow rearomatization step
the solution was dried by addition of MgSO4. The black MnO2/MgSO4
slurry was filtered through sintered glass. After evaporation of the sol-
vent a dark yellow glass (3.190 g) was obtained as the crude product
which was purified by column chromatography over silica gel (eluent:
CH2Cl2 and MeOH). Pure compound 5 was obtained as a pale yellow
Diphenanthroline 10: A THF solution (70 mL) containing lithio deriva-
tive 9 [7 mmol, prepared from 1-bromo-3-trimethylsilylbenzene (1.603 g,
[17]
7 mmol) and tBuLi (14 mmol)]
was added through a cannula to a de-
gassed suspension of diphenanthroline 8 (0.950 g, 2.18 mmol) in anhy-
drous toluene (120 mL) at 68C. Upon addition of 9 onto 8 the initial
pale-yellow suspension turned dark red. The mixture was stirred under
argon for 3 h at 78C. Subsequent hydrolysis with water at 08C afforded a
bright yellow mixture from which THF was distilled under vacuum. After
the mixture had been decanted, the aqueous phase was extracted with
CH2Cl2 (3”100 mL) and the combined organic phases were rearomatized
with MnO2 (7 g). MgSO4 (10 g) was added to dry the organic phase and
the MnO2/MgSO4 slurry was filtered through sintered glass (porosity 4).
Evaporation of the solvents yielded 1.510 g of a pale yellow glass. Pure
compound 10 was obtained after column chromatography over silica gel
1
solid (1.980 g, 6.17 mmol) in 62% yield. H NMR (200 MHz, CDCl3): d=
8.36 (d, J=8.8 Hz, 2H, H-o), 8.26 (d, J=8.6 Hz, 1H, H-7), 8.18 (d, J=
8.3 Hz, 1H, H-4), 8.08 (d, J=8.6 Hz, 1H, H-8), 7.77 (AB, J=8.6 Hz, 2H,
H-5,6), 7.61 (d, J=8.3 Hz, 1H, H-3), 7.08 ppm (d, J=8.8 Hz, 2H, H-m);
13C (100 MHz, CD2Cl2): d=161.18, 156.97, 150.75, 146.21, 144.93, 139.03,
136.80, 131.83, 129.03, 127.94, 127.72, 126.92, 125.02, 123.94, 120.19,
114.26, 55.42 ppm; HR FAB-MS: m/z: 321.0790 [M+H]+, calcd 321.0795.
1
(eluent: CH2Cl2/2% MeOH) in 58% yield (0.924 g, 1.26 mmol). H NMR
(300 MHz, CD2Cl2): d=9.35 (t, J=1.8 Hz, 1H, H-ap), 8.80 (dd, J1 =7.7,
J2 =1.8 Hz, 2H, H-bp), 8.74 (brs, 2H, H-d), 8.46 (m, 2H, H-a), 8.41 (brs,
4H, H-3,4), 8.35 (d, J=8.4 Hz, 2H, H-7), 8.21 (d, J=8.4 Hz, 2H, H-8),
7.85 (s, 4H, H-5,6), 7.84 (t, J=7.7 Hz, 1H, H-cp), 7.68 (dt, J1 =7.7, J2 =
1.6 Hz, 2H, H-c), 7.56 (t, J=7.7 Hz, 2H, H-b), 0.40 ppm (s, 18H, SiMe3);
13C NMR (75 MHz, CDCl3): d=157.02, 156.49, 146.18, 146.16, 141.04,
139.72, 138.56, 136.94, 136.91, 134.53, 132.72, 129.62, 129.13, 128.09,
128.06, 127.92, 126.21, 126.09, 126.01, 120.04, 119.97, À0.95 ppm; HR
FAB-MS: m/z: 731.3020 [M+H]+, calcd 731.3026.
2-Bromo-9-(p-anisyl)phenanthroline (6): Exchange for the chlorine in 5
by a bromine atom was performed following a modification to a proce-
dure described in the literature.[16] Under a stream of argon, neat PBr3
(30 mL) was poured into a small two-necked round-bottom flask contain-
ing 5 (600 mg, 1.95 mmol). The resulting bright yellow mixture was then
refluxed at 1708C for 45 min under argon. The yellow color progressively
turned greenish-black during the heating process. After reflux the dark
suspension was stirred overnight at room temperature under argon. Sub-
sequent careful hydrolysis on crushed ice afforded a yellow suspension of
6 in a strongly acidic medium (pH 1). NaOH pellets were then added
until the solution became slightly basic (pH 8), and the bromide 6 was ex-
tracted with a mixture of CH2Cl2 and CHCl3. After decanting the mix-
ture, the organic phase was dried over MgSO4, filtered, and evaporated
to dryness to yield 620 mg of a colorless solid. This crude product was pu-
rified by column chromatography over silica gel (eluent: CH2Cl2/hexane
1:1 to pure CH2Cl2) to afford pure 6 in 81% yield (577 mg, 1.58 mmol).
1H NMR (300 MHz, CDCl3): d=8.36 (d, J=9.0 Hz, 2H, H-o), 8.27 (d,
J=8.5 Hz, 1H, H-7), 8.09 (d, J=8.5 Hz, 1H, H-8), 8.08 (d, J=8.8 Hz,
1H, H-4), 7.98 (AB, J=8.7 Hz, 2H, H-5,6), 7.72 (d, J=8.8 Hz, 1H, H-3),
7.09 (d, J=9.0 Hz, 2H, H-m), 3.90 ppm (s, 3H, OCH3); 13C (75 MHz,
CDCl3): d=161.16, 157.29, 146.81, 144.84, 142.45, 138.27, 136.80, 131.77,
129.28, 127.95, 127.73, 127.49, 127.01, 125.06, 120.24, 114.26, 55.43 ppm;
ES-MS: m/z: 366.2 [M+H]+, calcd 366.2.
Diiodo-diphenanthroline 11: Diphenanthroline 10 (570 mg, 0.8 mmol)
was placed in a two-necked round-bottom flask and dissolved in CH2Cl2
(100 mL). The solution was purged three times with Ar/vacuum and
cooled to 08C in an ice-bath. ICl (160 mg, 1.02 mmol) in CH2Cl2 (10 mL)
was added and the ice-bath was removed. After 4 h, the solution was
quenched with a saturated solution of Na2S2O5. The aqueous layer was
extracted with CH2Cl2 and dried with MgSO4. After purification by chro-
matography on alumina (CH2Cl2), 11 was isolated as a white solid
1
(650 mg, CH2Cl2 adduct) in 98% yield. H NMR (300 MHz, CD2Cl2): d=
7.19 (t, J=7.8 Hz, 2H, H-b), 7.78 (dt, J=7.8, J=1.6 Hz, 2H, H-c), 7.86
(t, J=7.6 Hz, 1H, H-cp), 7.87 (d, J=8.8 Hz, 2H, H-6), 7.91 (d, J=8.8 Hz,
2H, H-5), 8.12 (d, J=8.4 Hz, 2H, H-8), 8.38 (d, J=8.4 Hz, 2H, H-7),
8.45 (d, 4H, H-3,4), 8.47 (m, 2H, H-a), 8.65 (dd, J=7.7, J=1.8 Hz, 2H,
H-bp), 8.80 (t, J=1.6 Hz, 2H, H-d), 9.59 ppm (t, J=1.8 Hz, 1H, H-ap);
13C NMR (75 MHz, CDCl3): d=159.82, 159.30, 155.63, 155.40, 143.06,
141.39, 140.36, 138.02, 137.71, 136.46, 135.09, 131.34, 130.76, 129.19,
129.09, 128.12, 127.63, 127.03, 124.81, 124.29, 116.97, 113.15 ppm; FAB-
MS: m/z: 839.1 [M+H]+, calcd 839.4.
Diphenanthroline 8: 1,3-Dilithiobenzene (7) was prepared by adding four
equivalents of tBuLi (45 mmol, 25 mL of a 1.8 molLÀ1 solution) dropwise
to a degassed THF solution (70 mL) of 1,3-dibromobenzene (2.832 g,
12 mmol) at À788C. After all the tBuLi had been added, the solution
was allowed to warm to +58C twice. The clear pale yellow dilithioben-
zene solution was then added through a cannula to a degassed solution
of anhydrous phenanthroline (4.0 g, 22.2 mmol) in THF (140 mL) at
room temperature under argon. The initial pale yellow solution of phe-
nanthroline in THF immediately turned dark red. This mixture was stir-
red for 48 h at room temperature under argon before being quenched
Diphenanthroline diboronic ester 12: Diiodo-diphenanthroline 11
(650 mg, 0.68 mmol), bis-neopentyl diboron (340 mg, 1.49 mmol), KOAc
(400 mg, 4.10 mmol), and [Pd(dppf)Cl2]·CH2Cl2 (33 mg, 0.04 mmol) were
dissolved in freshly distilled dioxane (60 mL). The mixture was stirred
under argon at 808C for five days. The solution was then cooled to room
temperature and water (60 mL) was added. The product was extracted
from the aqueous phase with CH2Cl2. The organic phase was dried with
MgSO4, filtered, and evaporated. The resulting black solid was then puri-
fied by chromatography over silica using CH2Cl2/MeOH as eluent. The
4382
ꢀ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Chem. Eur. J. 2005, 11, 4374 – 4386

Synthesis of Multi-phenanthroline Ligands
FULL PAPER
product underwent substantial decomposition on the column (hydrolysis
of the diol protecting group). A black solid (320 mg) was recovered. 1H
NMR and mass spectrometric analyses were in good agreement with the
expected structure of 12 (58% yield). 1H NMR (300 MHz, CDCl3): d=
1.04 (s, 12H, CH3), 3.80 (s, 8H, CH2), 7.63 (t, J=7.7 Hz, 2H), 7.84 (m,
4H), 7.98 (dt, J1 =7.3, J2 =1.1 Hz, 2H), 8.28 (d, J=8.4 Hz, 2H), 8.33 (d,
J=8.4 Hz, 2H), 8.39 (d J=8.4 Hz, 2H), 8.50 (d, J=8.4 Hz, 2H), 8.78 (dd,
J1 =7.7, J2 =1.6 Hz, 2H), 8.80 (brs, 2H), 8.87 (dt, J1 =7.9, J2 =1.5 Hz,
2H), 9.74 ppm (t, J=1.8 Hz, 1H); FAB-MS: m/z: 811.4 [M+H]+, calcd
811.5.
chromatography over silica gel (CH2Cl2/MeOH) to yield diallyl-tetraphe-
nanthroline 1 (260 mg, 80% yield). H NMR (300 MHz, CD2Cl2): d=3.60
1
(m, 24H, H-C,D,E,F,G,H), 3.88 (t, 4H, H-B), 3.97 (dt, 4H, H-I), 4.18 (t,
4H, H-A), 5.20 (m, 4H, H-K), 5.89 (m, 2H, H-J), 7.02 (d, J=8.7 Hz, 4H,
H-m), 7.46 (d, J=8.8 Hz, 2H, H-5’), 7.59 (d, J=8.8 Hz, 2H, H-5), 7.60
(d, J=8.7 Hz, 2H, H-6’), 7.70 (d, J=8.8 Hz, 2H, H-6), 7.75 (t, 1H, H-c),
7.76 (t, J=7.6 Hz, 2H, H-c’), 8.04 (d, J=8.7 Hz, 2H, H-4’), 8.07 (d, J=
8.7 Hz, 2H, H-8’), 8.13 (d, J=8.5 Hz, 2H, H-4), 8.30 (m, 10H, H-
7,8,3,3’,7’), 8.42 (d, J=8.7 Hz, 4H, H-o), 8.52 (d, J=7.0 Hz, 2H, H-d’),
8.58 (d, J=7.8 Hz, 2H, H-b), 8.63 (d, J=7.8 Hz, 2H, H-b’), 9.70 (brs,
2H, H-a’), 9.75 ppm (brs, 1H, H-a); FAB-MS: m/z: 1560.6 [M+H]+,
calcd 1560.8.
Tetraphenanthroline 13: Diphenanthroline 12 (295 mg, 0.36 mmol), bro-
mophenanthroline
6
(265 mg, 0.728 mmol), Pd(PPh3)4 (60 mg,
0.04 mmol), and K3PO4 (230 mg, 1.1 mmol) were added to DMF (20 mL).
After the mixture was degassed, the solution was stirred at 1008C for
two days. The reaction mixture was then allowed to cool to room temper-
ature. Upon addition of water (30 mL), a precipitate was formed. The
solid was filtered and purified over silica (CH2Cl2/CHCl3/4 to 7%
MeOH) to give the product 13 (252 mg) as a brown solid in 60% yield.
1H NMR (400 MHz, CDCl3): d=3.83 (s, 6H, OCH3), 6.99 (d, J=8.3 Hz,
4H, H-m), 7.38 (d, J=8.1 Hz, 2H, H-5’), 7.49 (d, J=8.7 Hz, 2H, H-5),
7.53 (d, J=8.1 Hz, 2H, H-6’), 7.61 (d, J=8.7 Hz, 2H, H-6), 7.68 (t, J=
7.9 Hz, 1H, H-c), 7.73 (t, J=7.9 Hz, 2H, H-c’), 8.00 (d, J=8.4 Hz, 2H,
H-4’), 8.04 (d, J=8.5 Hz, 2H, H-8’), 8.06 (d J=9.6 Hz, 2H, H-4), 8.21 (d,
J=8.3 Hz, 2H, H-7’), 8.30–8.39 (m, 12H, H-7,8,3,3’, H-o), 8.48 (brd, 2H,
H-d’), 8.56 (dd, 2H, H-b), 8.64 (brd, 2H, H-b’), 9.68 (brs, 2H, H-a’),
9.72 ppm (brs, 1H, H-a); FAB-MS: m/z: 1156.3 [M+H]+, calcd 1156.3.
[(1)2·4Li]4+·(4PF6)4À: DiOH-tetraphenanthroline 1 (145 mg, 0.092 mmol)
was dissolved in CH2Cl2/MeOH (8:2, 10 mL) under argon and LiPF6
(32 mg, 0.21 mmol) was added to the solution. Li2CO3 (3 mg) was also
added to adjust the pH to 7. The solution was stirred for 3 h and then the
solvent was removed to quantitatively afford 176 mg of the double helix.
1H NMR (300 MHz, CD3CN): d=3.25 (m, 8H, H-A), 3.47 (m, 8H, H-B),
3.50–3.70 (m, 48H, H-C,D,E,F,G,H), 4.00 (dt, 8H, H-I), 5.20 (m, 8H, H-
K), 5.59 (d, J=8.4 Hz, 8H, H-m), 5.92 (m, 4H, H-J), 6.00 (dd, 8H, H-
8,3), 6.20 (d, J=8.4 Hz, 4H, H-3’), 6.75–6.68 (m, 20H, H-o, H-b,b’,d’),
6.89 (t, J=7.5 Hz, 2H, H-c), 6.94 (t, J=7.9 Hz, 4H, H-c’), 7.54–7.40 (m,
22H, H-4,4’,7,8’,a,a’), 7.65 (m, 12H, H-5,5’,6), 7.81 (d, J=8.8 Hz, 4H, H-
6’), 8.22 ppm (d, J=8.5 Hz, 4H, H-7’); HR ES-MS: m/z: 1718.6457
[MÀ2PF6]2+, 1097.4533 [MÀ3PF6]3+, 786.8472 [MÀ4PF6]4+; calcd for
C200H172N16O20Li4P2F12 [MÀ2PF6]2+: 1718.6466.
Diphenol 14: Pyridine (17 mL) was poured into a three-necked flask.
While stirring, HCl (36%, 19 mL) was slowly added. The reaction was
highly exothermic and fuming. After addition of HCl the flask was fitted
with a distillation head. To distil the water from the mixture the flask
was heated with a mantle until the internal temperature reached 210–
2208C (boiling point of anhydrous pyridine hydrochloride). The distilla-
tion head was then removed and the mixture was allowed to cool to
1408C. A powder funnel was placed in the large middle neck and, whilst
bubbling argon gas through the right neck, tetraphenanthroline 13
(252 mg, 0.22 mmol) was poured in one batch into the flask through the
left neck. The reaction flask was then fitted with a water condenser
equipped with a two-way Claisen adaptor connected on one side to a
source of Ar and on the other side to a mineral oil bubbler. After estab-
lishing an argon atmosphere in the flask, the contents were stirred under
reflux for 3 h (internal temperature 210–2208C).The hot brown stirred
mixture was cooled to 1108C and diluted by slow and careful injections
of hot water. The resulting brown suspension was poured into a conical
flask containing hot water (60 mL). The solution was allowed to cool to
room temperature and then the suspension was neutralized by the addi-
tion of KOH pellets to the flask until a pH of 7.3 was obtained. Then the
solid was filtered and air-dried on a porous dish overnight and finally
dried in a vacuum desiccator in the presence of KOH to obtain diOH-tet-
raphenanthroline 14 as a brown solid (235 mg, 95% yield). 1H NMR
(300 MHz, [D6]DMSO): d=6.88 (d, J=8.4 Hz, 4H), 7.62 (t, J=8.0 Hz,
3H), 7.70 (d, J=8.8 Hz, 2H), 7.82 (d, J=8.8 Hz, 2H), 7.91 (d, J=8.8 Hz,
2H), 7.98 (d, J=8.8 Hz, 2H), 8.24 (d, J=8.6 Hz, 2H), 8.29 (d, J=8.6 Hz,
2H), 8.40 (d, J=8.4 Hz, 4H), 8.44–8.74 (m, 18H), 9.68 (brs, 2H), 9.82
(brs, 1H), 9.88 ppm (brs, 2H); FAB-MS: m/z: 1128.4 [M+H]+, calcd
1128.3.
Diphenanthroline 19: A solution of 1-lithio-3-bromobenzenze (16) [pre-
pared from 1,3-dibromobenzene (2.08 g, 8.8 mmol) and n-BuLi
(8.8 mmol) at a temperature of between 2 and 48C] in Et2O (60 mL) was
added through a cannula to a degassed suspension of 15 (2.29 g, 8 mmol)
in Et2O (100 mL) maintained at 28C. The dark red mixture of 17 ob-
tained after addition of the lithio-derivative 16 was maintained with stir-
ring at 48C under argon for a further 2 h. nBuLi (6.8 mL, 10.6 mmol) was
then injected rapidly (5 min) into this mixture at 38C to give a solution
of phenanthroline 18. This solution was stirred at 5–108C for 2 h before
being added through a cannula to a degassed solution of 2-chlorophenan-
throline (3) (1.932 g, 9 mmol) in toluene (150 mL) at 2–48C. The result-
ing dark red solution was stirred overnight while the temperature slowly
returned to room temperature. After hydrolysis at 08C, the organic phase
was decanted and the aqueous phase extracted with CH2Cl2 (3”100 mL).
The combined organic layers were treated with MnO2 (47 g), dried with
MgSO4, and evaporated to dryness after filtration of the MnO2/MgSO4
slurry to afford a dark-brown crude. This was subjected to column chro-
matography over silica gel twice (eluent: CH2Cl2/1% MeOH) to give
1
pure 19 in 34% yield (1.565 g, 2.72 mmol). H NMR (500 MHz, CD2Cl2):
d=9.35 (t, J=1.6 Hz, 1H, H-a), 8.59 (dd, J1 =7.9, J2 =1.7 Hz, 2H, H-b),
8.45 (d, J=8.9 Hz, 2H, H-o), 8.42 (AB, 2H, H-3’, H-4’), 8.39 (d, J=
8.4 Hz, 1H, H-4), 8.33 (d, J=8.4 Hz, 1H, H-3), 8.31 (d, J=8.4 Hz, 1H,
H-7), 8.25 (d, J=8.4 Hz, 1H, H-7’), 8.12 (d, J=8.4 Hz, 1H, H-8), 7.82 (d,
J=8.8 Hz, 1H, H-5’), 7.75 (t, J=7.9 Hz, 1H, H-c), 7.73 (d, J=8.9 Hz,
1H, H-6’), 7.74 (s, 2H, H-5,6), 7.57 (d, J=8.2 Hz, 1H, H-8’), 7.05 (d, J=
8.9 Hz, 2H, H-m), 3.87 ppm (s, 3H, OMe); FAB-MS: m/z: 576.0 [M+H]+
, calcd 576.0.
Diphenanthroline 20: Exchange of the chlorine atom by the bromine
atom was performed following a modification to the procedure described
in the literature.[3] Under a stream of argon, pure PBr3 (25 mL) was
poured onto the neat solid diphenanthroline 19 (1.030 g, 1.79 mmol) in a
two-necked round-bottom flask fitted with a reflux condenser. The result-
ing bright yellow mixture was then refluxed for 40 min at 1708C. During
the heating, the initial yellow color rapidly turned greenish-black. The re-
sulting dark suspension was stirred overnight at room temperature under
argon. Subsequent careful hydrolysis on crushed ice afforded a yellow-
greenish precipitate of 20 in a strongly acidic medium (pH 1). KOH pel-
lets were added until the medium was slightly basic (pH 7.30), and then
the bromide 20 was extracted with a mixture of CH2Cl2 and CHCl3.
After decanting the mixture, the combined organic phases were dried
over MgSO4, filtered, and evaporated to dryness to afford 975 mg of
crude bromide 20. This crude was purified by column chromatography on
Diolefinic tetraphenanthroline 1: DiOH-tetraphenanthroline 14 (230 mg,
0.20 mmol) was dissolved in dry DMF (50 mL) and the solution was de-
gassed and heated at 658C. Cs2CO3 (1.32 g, 4.10 mmol) was then added
and the solution stirred for 45 min. Bromo-allyl-poly(ethylene glycol)
(0.422 g, 1.42 mmol) was dissolved in dry and degassed DMF (15 mL)
and placed in an addition funnel. The bromo compound was then added
dropwise to the diOH-tetraphenanthroline 14. After 6 h, further Cs2CO3
(800 mg) and the bromo compound (400 mg) were added, and the solu-
tion was stirred for 1 day. Then DMF was removed under vacuum. The
solid was washed with diethyl ether and then dissolved in CH2Cl2/H2O
(50:50 mL). The aqueous phase was extracted with CH2Cl2 (50 mL) and
the organic layers were combined. The solvent was removed under
vacuum to afford a clear brown solid (400 mg) which was purified by
Chem. Eur. J. 2005, 11, 4374 – 4386
www.chemeurj.org
ꢀ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
4383

J.-P. Sauvage et al.
silica gel (eluent: CH2Cl2/0–10% MeOH) to afford pure 20 in 65% yield
(715 mg, 1.15 mmol). H NMR (300 MHz, CD2Cl2): d=9.35 (t, J=1.5 Hz,
H-a), 8.73 (brs, 2H, H-d), 8.31 (d, J=8.4 Hz, 2H, H-4,7), 8.27 (d, J=
8.4 Hz, 2H, H-3,8), 7.96 (dt, J1 =7.3, J2 =1.2 Hz, 2H, H-c), 7.79 (s, 2H,
H-5,6), 7.65 (t, J=7.9 Hz, 2H, H-b), 1.41 ppm (s, 24H, CH3); 13C NMR
(75 MHz, CDCl3): d=156.69, 146.14, 138.67, 136.8, 135.94, 133.53, 131.39,
131.07, 128.46, 127.96, 126.00, 120.11, 83.92, 24.99; HR FAB-MS: m/z:
585.3107 [M+H]+ , calcd 585.3096.
1
1H, H-a), 8.59 (dd, J1 =7.7, J2 =1.5 Hz, 2H, H-b), 8.46 (d, J=9.0 Hz, 2H,
H-o), 8.43 (brs, 2H, H -3’,4’), 8.40 (d, J=8.4 Hz, 1H, H-4), 8.37 (d, J=
8.4 Hz, 1H, H-3), 8.31 (d, J=8.4 Hz, 1H, H-7), 8.14 (d, J=8.4 Hz, 1H,
H-7’), 8.12 (d, J=8.4 Hz, 1H, H-8), 7.93 (d, J=8.8 Hz, 1H, H-5’), 7.85 (t,
J=7.7 Hz, 1H, H-c), 7.82 (d, J=8.8 Hz, 1H, H-6’), 7.81 (s, 2H, H-5,6),
7.78 (d, J=8.4 Hz, 1H, H-8’), 7.07 (d, J=9.0 Hz, 2H, H-m), 3.89 ppm (s,
3H, OMe); 13C NMR (75 MHz, CDCl3): d=160.88, 157.69, 156.38,
156.19, 142.45, 139.54, 139.48, 138.35, 137.21, 137.02, 136.89, 131.99,
129.49, 129.31, 129.07, 128.76, 128.08, 127.99, 127.92, 127.83, 127.49,
127.01, 126.89, 126.04, 125.64, 125.52, 121.25, 120.16, 119.59, 114.09,
55.33 ppm; HR ES-MS: m/z: 619.1150 [M+H]+, calcd 619.1133.
Diboronic acid 24: 3m HCl (30 mL) was added, at room temperature, to
diester 23 (521 mg, 0.892 mmol) dissolved in THF (30 mL). The resulting
ochre-beige suspension was stirred at room temperature for four days.
Subsequent evaporation of THF afforded a yellow precipitate in the re-
maining acidic aqueous phase. The latter was neutralized (pH 7.1) by ad-
dition of a concentrated KOH solution. The resulting neutral beige pre-
cipitate was isolated by filtration through paper, washed with water, and
air-dried to afford pure diboronic acid 24 (373 mg, 0.888 mmol) in 99%
yield. 1H NMR (300 MHz, CD3OD and 3 drops of a DCl solution in
D2O): d=8.88 (d, J=8.6 Hz, 2H, H-4,7), 8.50 (brs, 2H, H-d), 8.41 (d, J=
8.6 Hz, 2H, H-3,8), 8.24 (m, 2H, H-a), 8.18 (s, 2H, H-5,6), 7.92 (d, J=
7.3 Hz, 2H, H-c), 7.54 ppm (t, J=7.5 Hz, 2H, H-b); HR FAB-MS: m/z:
449.1867 [M+H]+ (the dimethyl ester was formed in the conditions used
for this product), calcd 449.1844.
Monosubstituted phenanthroline 21: A solution of 1-lithio-3-bromoben-
zene 16 [prepared from 1,3-dibromobenzene (9.44 g, 40 mmol) by inter-
conversion with nBuLi (25 mL, 40 mmol) at 2–48C] in diethyl ether
(120 mL) was added to a degassed solution (150 mL) of anhydrous 1,10-
phenanthroline (6.84 g, 38 mmol) in THF also maintained at 2–48C.
After stirring for 2 h at 3–48C, the mixture was hydrolyzed by injection
of water (50 mL) at a low temperature (0–58C). The solvents were
evaporated and the dark-yellow crude taken up in CH2Cl2/H2O. After de-
canting the mixture, the aqueous layer was extracted with CH2Cl2 (3”
100 mL). The combined organic phases were subsequently rearomatized
with MnO2 (30 g) and dried with MgSO4. Filtration of the MnO2/MgSO4
slurry through sintered glass (porosity 4) and evaporation of the solvent
afforded crude 21. Pure 21 was obtained by column chromatography
over silica gel (eluent: CH2Cl2/0–5% MeOH) as a pale-yellow glass in
32% yield (4.085 g, 12.194 mmol). 1H NMR (300 MHz, CDCl3): d=9.25
(dd, J1 =4.2, J2 =1.7 Hz, 1H, H-9), 8.47 (dd, J1 =2.0, J2 =1.7 Hz, 1H, H-
d), 8.33 (d, J=8.4 Hz, 1H, H-4), 8.29 (m, 2H, H-7, H-a), 8.06 (d, J=
8.4 Hz, 1H, H-3), 7.81 (s, 2H, H-5,6), 7.66 (dd, J1 =8.1, J2 =4.2 Hz, 1H,
H-8), 7.62 (ddd, J=7.9 Hz, 1H, H-c), 7.42 ppm (t, J=7.9 Hz, 1H, H-b);
13C NMR (75 MHz, CDCl3): d=155.86, 150.40, 146.21, 146.02, 141.65,
136.97, 136.08, 132.17, 130.78, 130.23, 129.72, 127.72, 126.60, 126.53,
126.52, 126.20, 123.02, 120.48 ppm. HR FAB-MS: m/z: 335.0160 [M+H]+
, calcd 335.0184.
Pentaphenanthroline 25: Diphenanthroline 20 (715 mg, 1.154 mmol), di-
boronic acid 24 (267 mg, 0.635 mmol), [Pd(PPh3)4] (60 mg, 0.05 mmol),
and K3PO4 (735 mg, 3.46 mmol) were poured as solids into a three-
necked round-bottom flask under a stream of argon at room tempera-
ture. The mixture of solids was stirred and degassed three times before it
was covered with dry and degassed DMF (50 mL) and heated to 1008C.
Except for K3PO4, all the solids dissolved at this temperature. The mix-
ture was then stirred and heated for 48 h and further [Pd(PPh3)4] was
added (60 mg after 3 and 27 h). The resulting dark-brown reaction mix-
ture was cooled to room temperature and diluted with water (200 mL).
The beige precipitate which appeared was filtered through paper, washed
with water and air-dried on a porous dish to afford 1.268 g of an ochre
solid. The latter was suspended in CH2Cl2 (50 mL) and filtered through a
column of dry silica gel. By using CH2Cl2 containing increasing amounts
of MeOH (0–7%) as eluent all the organic compounds were eluted other
than 25 which remained on the solid silica support. The silica gel in the
column was then poured into
a round-bottom flask, covered with
2,9-Bis(m-bromophenyl)-1,10-phenanthroline (22): A solution of 1-lithio-
3-bromobenzene 16 [prepared from 1,3-dibromobenzene (3.54 g,
15 mmol) by interconversion with nBuLi (12 mL, 16 mmol) at 2–48C] in
diethyl ether (40 mL) was added to a degassed solution of phenanthro-
line 21 (3.35 g, 10 mmol) in THF/Et2O (40:50 mL) maintained at 2–48C.
After stirring for 2 h at 3–48C, the mixture was hydrolyzed by injection
of water (50 mL) at 08C. The solvents (THF and Et2O) were evaporated
and the dark yellow-brown crude taken up in CH2Cl2/H2O. After decant-
ing the mixture, the aqueous layer was extracted with CH2Cl2 (3”
50 mL). The combined organic phases were subsequently rearomatized
with MnO2 (26 g) and dried with MgSO4. Filtration of the MnO2/MgSO4
slurry through sintered glass (porosity 4) and evaporation of the solvent
afforded crude 22. Pure 22 was obtained by column chromatography
over silica gel (eluent: CH2Cl2/hexane, 80:20) as a colorless solid in 24%
yield (1.19 g, 2.43 mmol). 1H NMR (200 MHz, CD2Cl2): d=8.71 (dd, J1 =
2.0, J2 =1.7 Hz, 2H, H-d), 8.36 (m, 4H, H-4,7, H-a), 8.13 (d, J=8.4 Hz,
2H, H-3,8), 7.82 (s, 2H, H-5,6), 7.64 (ddd, J=7.9 Hz, 2H, H-c), 7.47 ppm
(t, J=7.9 Hz, 2H, H-b).
CH2Cl2/MeOH (93:7) (150 mL) before LiPF6 (680 mg, 4.5 mmol) was
added under a stream of argon. The heterogeneous mixture was there-
after gently stirred at room temperature for four days under argon. The
mixture was then decanted, filtered through sintered glass, and the silica
gel washed with CH2Cl2 (100 mL) and CH3CN (100 mL). CF3COOH
(1 mL) was added to the combined filtrate and washings. The bright
yellow solution obtained was evaporated to dryness to afford fully pro-
tonated 25 (1.024 g, 0.794 mmol) in 83% yield. 1H NMR (300 MHz,
CD3CN): d=9.74 (brs, 2H), 9.08 (d, J=8.8 Hz, 2H), 8.63 (brs, 2H), 8.86
(d, J=8.6 Hz, 2H), 8.35 (d, J=8.5 Hz, 2H), 8.22 (d, J=8.9 Hz, 2H), 8.12
(d, J=8.9 Hz, 2H), 8.05–7.89 (m, 10H), 7.72 (m, 4H), 7.65 (s, 2H), 7.47
(m, 6H), 7.35 (m, 6H), 7.19 (m, 6H), 6.94 (d, J=8.8 Hz, 2H), 5.97 (d, J=
8.7 Hz, 4H), 3.27 ppm (s, 6H); ES-MS: m/z: 1410.5 [M+H]+, calcd
1410.6; 705.5 [M+2H]2+, calcd 705.7; 470.7 [M+3H]3+, calcd 470.8; 353.3
[M+4H]4+, calcd 353.3.
À
Diphenol pentaphenanthroline 26: Starting from (25·5H)5+·5PF6
(1.024 g, 0.479 mmol) and excess pyridinium chloride [prepared from pyr-
idine
(16 mL)
and
HCl
(36%,
17.6 mL)],
diphenol
26
Diboronic ester 23: Under a stream of argon, dibromide 22 (490 mg,
1 mmol), bis-neopentyl diboron (558 mg, 2.2 mmol), and KOAc (589 mg,
6 mmol) were poured into a three-necked round-bottom flask. The solid
mixture of compounds was covered with freshly distilled dioxane
(70 mL). The resulting suspension was degassed three times and warmed
to reflux (808C) before the catalyst [Pd(dppf)Cl2] (49 mg, 0.06 mmol)
was added as a solid in one batch. Monitoring by TLC showed that the
reaction was completed after heating overnight. The dark brown solution
was poured into cold water (100 mL). The gray precipitate which was
formed was filtered through paper and washed three times with cold
water. The air-dried crude gray solid was redissolved in CH2Cl2 and puri-
fied by rapid column chromatography over silica gel (eluent: CH2Cl2/0–
5% MeOH) to afford pure 23in 90% yield (524 mg, 0.90 mmol). 1H
NMR (300 MHz, CDCl3): d=8.88 (m, J1 =7.9, J2 =1.8, J3 =1.2 Hz, 2H,
(617 mg,0.446 mmol) was obtained in 93% yield by following the proce-
dure used for the preparation of diphenol 14. Owing to the very low solu-
bility of 26, no satisfactory NMR analysis could be obtained. ES-MS:
m/z: 1382.5 [M+H]+, calcd 1382.5; 1404.5 [M+Na]+, calcd 1404.5; 691.5
[M+2H]2+, calcd 691.7; 461.4 [M+3H]3+, calcd 461.5; 346.3 [M+4H]4+
,
calcd 346.4.
Diolefinic pentaphenanthroline 2: Diphenol pentaphenanthroline 26
(O.612 g, 0.443 mmol) was suspended in dry DMF (200 mL). The mixture
was degassed and warmed to 658C and then Cs2CO3 (2.02 g, 8.86 mmol)
was added. The mixture was stirred at 658C for 1 h before a degassed so-
lution of bromo-allyl-poly(ethylene glycol) (1.05 g, 3.10 mmol) in DMF
(15 mL) was slowly added through an addition funnel (over a period of
half an hour). The mixture was stirred at 658C for 6 h after which addi-
4384
ꢀ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
Chem. Eur. J. 2005, 11, 4374 – 4386

Synthesis of Multi-phenanthroline Ligands
FULL PAPER
tional Cs2CO3 (1.8 g) and olefinic chain (0.700 g, 2.05 mmol) were added.
After stirring at 658C under argon overnight, the mixture was evaporated
to dryness. The solid residue was washed four times with Et2O ( to
remove excess olefinic chain) and thereafter suspended in water. The
ochre-beige precipitate was filtered through paper and washed with
water before being dried in air on a porous dish. Compound 2 thus ob-
tained in 62% yield (0.520 g, 0.273 mmol) was used without further puri-
fication. 1H NMR (500 MHz, CD2Cl2): d=9.78 (brs, 2H, H-a), 9.69 (brs,
2H, H-a’), 8.63 (d, J=7.9 Hz, 2H, H-d’), 8.60 (d, J=7.3 Hz, 2H, H-d),
8.54 (m, 4H, H-b,b’), 8.41 (d, J=8.6 Hz, 4H, H-o), 8.36 (brs, 4H, H-
7’,8’), 8.30 (d, J=7.9 Hz, 2H, H-3’’), 8.29 (d, J=7.7 Hz, 2H, H-3,8), 8.27
(d, J=8.2 Hz, 2H, H-3’), 8.21 (d, J=8.6 Hz, 2H, H-7’’), 8.10 (d, J=
8.2 Hz, 2H, H-4’), 8.08 (d, J=8.6 Hz, 2H, H-8’’), 8.05 (d, J=7.7 Hz, 2H,
H-4,7), 8.04 (d, J=7.9 Hz, 2H, H-4’’), 7.72 (t, J=7.9 Hz, 2H, H-c’), 7.66
(t, J=7.3 Hz, 2H, H-c), 7.64 (d, J=8.6 Hz, 2H, H-6’), 7.57 (d, J=8.6 Hz,
2H, H-6’’), 7.55 (d, J=8.6 Hz, 2H, H-5’), 7.45 (d, J=8.6 Hz, 2H, H-5’’),
7.37 (s, 2H, H-5,6), 7.03 (d, J=8.6 Hz, 4H, H-m), 5.88–5.85 (m, 2H, H-
L), 5.26–5.11 (m, 4H, H-M), 4.17 (t, J=4.1 Hz, 4H, H-A), 3.97–3.93 (m,
4H, H-K), 3.87 (t, J=4.1 Hz, 4H, H-B), 3.76–3.50 (m, 32H, H-C,D,E,F,-
(d, J=8.5 Hz, 8H, H-m), 5.27–5.14 (m, 8H, H-M), 3.97 (td, J=5.6 Hz,
8H, H-K), 3.75–3.59 (m, 64H, H-C,D,E,F,G,H,I,J), 3.55 (m, 8H, H-B),
3.34 ppm (m, 8H, H-A); HR ES-MS: m/z: m/3 at 1414.1270
([(2)2·3Li·2Cu]5+·(2PF6)2À), calcd 1414.O986; m/4 at 1024.3433
([(2)2·3Li·2Cu]5+·(PF6)À),
calcd
1024.3329;
m/5
at
790.4849
([(2)2·3Li·2Cu]5+), calcd 790.4735; m/3 at 1363.4724 ([(2)2·2Li·2Cu]4+
·(PF6)À), calcd 1363.4639; m/4 at 986.3486 ([(2)2·2Li·2Cu]4+), calcd
986.3569.
[1] a) For early work, see: G. Schill, Catenanes, Rotaxanes and Knots,
Academic Press, New York and London, 1971; b) for the first cop-
per(i)-templated synthesis of a catenane, see: C. O. Dietrich-Bu-
checker, J.-P. Sauvage, J.-P Kintzinger, Tetrahedron Lett. 1983, 24,
5095.
[2] a) C. O. Dietrich-Buchecker, J.-P. Sauvage, J.-M. Kern, J. Am. Chem.
Soc. 1984, 106, 3043; b) C. O. Dietrich-Buchecker, J.-P. Sauvage, Tet-
rahedron 1990, 46, 503.
[3] a) Molecular Catenanes, Rotaxanes and Knots, (Eds.: J.-P. Sauvage,
C. Dietrich-Buchecker), Wiley-VCH, Weinheim, 1999; b) F. Vçgtle,
T. Dꢁnnwald, T. Schmidt, Acc. Chem. Res. 1996, 29, 451; c) M.
Fujita, Acc. Chem. Res. 1999, 32, 53; d) Special Issue of New. J.
Chem. 1993, 17, June issue; guest editor: J.-P. Sauvage; e) C. O. Die-
trich-Buchecker, J.-P. Sauvage, Angew. Chem. 1989, 101, 192;
Angew. Chem. Int. Ed. Engl. 1989, 28, 189; f) C. O. Dietrich-Bu-
checker, J. Guilheim, C. Pascard, J.-P. Sauvage, Angew. Chem. 1990,
102, 1202; Angew. Chem. Int. Ed. Engl. 1990, 29, 1154.
[4] a) L. Hogg, D. A. Leigh, P. J. Lusby, A. Morelli, S. Parsons, J. K. Y.
Wong, Angew. Chem. 2004, 116, 1238; Angew. Chem. Int. Ed. 2004,
43, 1218; b) D. A. Leigh, P. J. Lusby, S. J. Teat, A. J. Wilson, J. K. Y.
Wong, Angew. Chem. 2001, 113, 1586; Angew. Chem. Int. Ed. 2001,
40, 1538.
G,H,I,J); ES-MS: m/z: 1902.8 [M+H]+, calcd 1903.2; 952.0 [M+2H]2+
calcd 952.1; 634.9 [M+3H]3+, calcd 635.0.
,
Lithium complex [(2)2·5Li]5+C(5PF6)5À: LiPF6 (145 mg, 0.95 mmol) dis-
solved in MeOH (30 mL) was added to the brown solution of 2 (565 mg,
0.297 mmol) in CH2Cl2 (100 mL) at room temperature under a stream of
argon. Upon addition of LiPF6 the acidic solution (pH 3) was neutralized
by the addition of small amounts of solid Li2CO3 and three drops of
water. The resulting mixture was stirred under argon overnight. Monitor-
ing by 1H NMR spectroscopy allowed us to determine the necessary
amount of Li2CO3 needed for the formation of the lithium complex. At
the end of the reaction the solvents were evaporated to dryness to afford
crude complex [(2)2·5Li]5+·(5PF6)5À (515 mg, 0.113 mmol) as an ochre
glass in 76% yield. 1H NMR (300 MHz, CD2Cl2): d=8.14 (d, J=8.4 Hz,
4H, H-7’’), 7.76 (d, J=9.0 Hz, 4H, H-6’’), 7.64 (m, 16H, H-a’, H-5’’,5’,6’),
7.54 (s, 4H, H-5,6), 7.53 (d, J=8.4 Hz, 4H, H-4’’), 7.50 (d, J=8.4 Hz, 4H,
H-7’), 7.47 (d, J=8.4 Hz, 4H, H-4’), 7.37 (d, J=8.8 Hz, 4H, H-4,7), 7.34
(d, J=8.4 Hz, 4H, H-8’’), 7.24 (brs, 4H, H-a), 6.96 (t, J=7.7 Hz, 4H, H-
c’), 6.88 (t, J=7.5 Hz, 4H, H-c), 6.66 (d, J=7.7 Hz, 4H, H-d’), 6.65 (d,
J=8.6 Hz, 8H, H-o), 6.59 (d, J=6.4 Hz, 4H, H-b’), 6.57 (d, J=8.2 Hz,
4H, H-d), 6.49 (d, J=7.5 Hz, 4H, H-b), 6.10 (d, J=8.4 Hz, 4H, H-8’),
6.05 (d, J=8.4 Hz, 4H, H-3’’), 5.94 (d, J=8.4 Hz, 4H, H-3’), 5.90 (d, J=
8.8 Hz, 4H, H-3,8), 5.90–5.77 (m, 4H, H-L), 5.56 (d, J=8.6 Hz, 8H, H-
m), 5.26–5.14 (m, 8H, H-M), 3.98 (td, J=5.9 Hz, 8H, H-K), 3.75–3.63
(m, 64H, H-C,D,E,F,G,H,I,J), 3.60 (m, 8H, H-B), 3.32 ppm (m, 8H, H-
A); HR ES-MS: m/z: m/2 at 2136.8278 ([(2)2·5Li]5+·(3PF6)3À), calcd
2137.0241; m/3 at 1376.1988 ([(2)2·5Li]5+·(2PF6)2À), calcd 1376.3613; m/4
at 995.9139 ([(2)2·5Li]5+·(PF6)À), calcd996.0299; m/5 at 767.7443
([(2)2·5Li]5+), calcd 767.8311; m/2 at 2060.8009 ([(2)2·4Li]4+·(2PF6)2À),
calcd 2061.0720; m/3 at 1325.5394 ([(2)2·4Li]4+·(PF6)À) calcd 1325.7266;
m/4 at 958.1637 ([(2)2·4Li]4+), calcd 958.0539.
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Heteronuclear
Li–Cu
complexes
[(2)2·3Li·2Cu]5+·(5PF6)5À
and
À
[(2)2·2Li·2Cu]4+·(4PF6)4À: A degassed solution of [Cu(CH3CN)4]+·PF6
(44 mg, 0.118 mmol) in CH3CN (30 mL) was slowly added through a can-
nula to the degassed, ochre solution of [(2)2·5Li]5+·(5PF6)5À (262 mg,
0.0574 mmol) in CH2Cl2 (70 mL) at room temperature. After half an
hour all the copper had been added and the resulting solution was stirred
at room temperature and under argon for 48 h during which time the ini-
tial ochre solution gradually turned dark red. The solvents were then
evaporated to dryness to afford [(2)2·3Li·2Cu]5+·(5PF6)5À (267 mg,
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0.057 mmol) in quantitative yield as
a
dark-red solid. 1H NMR
(500 MHz, CD2Cl2 + MeOD + ascorbic acid): d=8.33 (brs, 4H, H-a’),
8.16 (d, J=8.5 Hz, 4H, H-7’’), 7.78 (d, J=9.0 Hz, 4H, H-6’’), 7.65 (d, J=
9.0 Hz, 4H, H-5’’), 7.63 (AB, J=8.8 Hz, 8H, H-5’,6’), 7.56 (s, 8H, H-5,6),
7.52 (d, J=8.4 Hz, 4H, H-4’’), 7.48 (d, J=8.2 Hz, 4H, H-7’), 7.46 (d, J=
8.1 Hz, 4H, H-4’), 7.41 (d, J=8.5 Hz, 4H, H-8’’), 7.38 (d, J=8.2 Hz, 4H,
H-4,7), 7.23 (brs, 4H, H-a), 6.91 (t, J=7.5 Hz, 4H, H-c’), 6.88 (t, J=
7.5 Hz, 4H, H-c), 6.75 (d, J=8.5 Hz, 8H, H-o), 6.61 (d, J=7.5 Hz, 4H,
H-d’), 6.59–6.55 (m, 8H, H-d,b’), 6.50 (d, J=7.5 Hz, 4H, H-b), 6.11 (d,
J=8.1 Hz, 4H, H-3’), 6.04 (d, J=8.4 Hz, 4H, H-3’’), 5.95 (d, J=8.2 Hz,
4H, H-8’), 5.90 (d, J=8.2 Hz, 4H, H-3,8), 5.93–5.85 (m, 4H, H-L), 5.52
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Received: December 9, 2004
Published online: May 4, 2005
4386
ꢀ 2005 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.chemeurj.org
Chem. Eur. J. 2005, 11, 4374 – 4386