A calix[4]arene-based bipyridine podand as versatile ligand for transition metal cations

Article abstract of DOI:10.1002/1099-0682(200203)2002:4<901::AID-EJIC901>3.0.CO;2-9

The calix[4]arene-based podand 1 which incorporates two 2,2′-bipyridine units and two benzyl units in alternate positions at the lower rim has been subjected to complexation studies with copper(I), copper(II), cobalt(II), nickel(II), and zinc(II). The reaction of 1 with Cu(MeCN)₄PF₆, afforded the expected mononuclear Cu^I complex. With cobalt(II), nickel(II), and zinc(II) chloride, 1 gave dinuclear tetrahedral complexes in which each bipyridine unit is associated to two chlorine atoms around the metal centre. With Zn^II, replacing the chloride ion for the trifluoromethanesulfonate ion resulted in the formation of the mononuclear complex species. The complexes thus obtained were fully characterised, notably by NMR techniques and, for the dinuclear cobalt, nickel and zinc species, by X-ray crystal structure analyses. Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002.

Full text of DOI:10.1002/1099-0682(200203)2002:4<901::AID-EJIC901>3.0.CO;2-9

FULL PAPER
A Calix[4]arene-Based Bipyridine Podand as Versatile Ligand for
Transition Metal Cations
Jean-Olivier Dalbavie,[a] Jean-Bernard Regnouf-de-Vains,*[a] Roger Lamartine,[b]
Monique Perrin,[b] Sylvain Lecocq,[b] and Bernard Fenet[c]
Keywords: Calixarenes / Bipyridines / Podands / Cobalt / Nickel / Zinc / Copper
The calix[4]arene-based podand 1 which incorporates two
2,2Ј-bipyridine units and two benzyl units in alternate posi-
tions at the lower rim has been subjected to complexation
studies with copper(I), copper(II), cobalt(II), nickel(II), and
zinc(II). The reaction of 1 with Cu(MeCN)4PF6 afforded the
expected mononuclear CuI complex. With cobalt(II),
nickel(II), and zinc(II) chloride, 1 gave dinuclear tetrahedral
chlorine atoms around the metal centre. With ZnII, replacing
the chloride ion for the trifluoromethanesulfonate ion re-
sulted in the formation of the mononuclear complex species.
The complexes thus obtained were fully characterised, not-
ably by NMR techniques and, for the dinuclear cobalt, nickel
and zinc species, by X-ray crystal structure analyses.
(
Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany,
complexes in which each bipyridine unit is associated to two 2002)
1. Introduction
different coordination geometries. We thus attempted to
employ this behaviour in a selective metal extraction pro-
cess based on the use of the tetrahedral geometry. In this
sense, we have recently demonstrated the interest of such
kinds of complexing structures with the bis(bipyridyl) li-
gand 1 displaying in alternate positions two opposing 2,2Ј-
bipyridyl chelating subunits and two opposing lipophilic
pendant benzyl groups. Complex 1 showed a very interest-
ing selective and quantitative extraction behaviour towards
AgI against PbII from neutral aqueous media.[7]
The abundant literature related to calixarenes illustrates
their important role in supramolecular chemistry,[1] and
particularly, as recently reviewed by Asfari et al.[2] or by
Matt et al. or Roundhill et al.,[3] as ligands for metal cat-
ions. Their complexation properties are attractive in the de-
velopment of selective extracting agents for metallic cations,
notably for rare metals. This can be accomplished through
their own binding sites (oxygen atoms, aryl rings), or by
their ability to act as carriers and spatial organisers of vari-
ous types of chelating agents, such as ethers, esters, amides
and their thio analogues, ketones, alkenes, ammonium spe-
cies, amino acids, phosphanes, or heterocycles.
Among these chelating subunits, introduced at the upper
or lower rims at the calix[4]arene platform, the biheterocyc-
lic systems have been moderately studied, with a major at-
tention brought to the 2,2Ј-bipyridine group,[4] and to the
corresponding RuII, CuI, and AgI complexes. Other contri-
butions have been devoted to ligands incorporating 2,2Ј-
bithiazole[5] or 2,2Ј-bipyrazine,[6] and their CuI complexes.
Depending on the nature, the number and the position of
the chelating units, such podands should be able to provide
The objective of the present report was to verify the com-
plexing behaviour of 1 toward various transition metal cat-
ions. We found this necessary because, on the one hand,
except for the above-mentioned metallic cations, the coordi-
nating behaviour of such ligands towards transition metal
species has not been reported until now, and on the other
hand our extraction study necessitated a better knowledge
of the other available complexes.
As assessed by X-ray crystallographic study of its picolyl
parent compound A,[8] complex 1 should give a mononu-
clear CuI pro-helicoidal tetrahedral complex, which should
also be encountered with AgI in complex B.[7,9] With CoCl2,
we recently reported the synthesis and X-ray crystal struc-
ture determination of a mononuclear complex involving a
calix[4]arene podand at the upper rim by a 2,2Ј-bipyridyl
unit, and in which the metal centre was coordinated in a
tetrahedral mode by the two chloride ions and the two bipy-
ridyl nitrogen atoms.[4f] This structure was proposed some
years ago by Newkome et al. for 6,6Ј-dimethyl-2,2Ј-bipyrid-
ine and CoCl2, NiCl2, ZnCl2, CuCl2, as well as less com-
mon metal species.[10] With the two close bipyridyl units of
[a]
´
GEVSM, UMR 7565 CNRS-UHP, Faculte de Pharmacie,
5, rue Albert Lebrun, 54001 Nancy Cedex, France
Fax: (internat.) ϩ 33-3/83179057
E-mail: jean-bernard.regnouf@pharma.u-nancy.fr
SROMB, UMR 5078 CNRS-UCBL,
43 Bd. du 11 Novembre 1918, 69622 Villeurbanne Cedex,
France
Centre Commun de RMN, UCBL-CPE,
43 Bd. du 11 Novembre 1918, 69622 Villeurbanne Cedex,
France
[b]
[c]
Eur. J. Inorg. Chem. 2002, 901Ϫ909
WILEY-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002 1434Ϫ1948/02/0404Ϫ0901 $ 17.50ϩ.50/0
901

J.-B. Regnouf-de-Vains et al.
FULL PAPER
the two corresponding anchoring methylene groups. In the
grooves thus generated, the benzyl groups should have
place, resulting in the discrimination of the two enantio-
topic OCH2 protons, characterised by a strong AB system
at δ ϭ 3.82, 4.01.
1, one may expect the two coordinating chlorine atoms to
be replaced by the second bipyridine unit, thus affording
mononuclear complexes with CoII, NiII, ZnII, and CuII;
however, dinuclear complexes could be obtained.
1
Figure 1. H NMR spectra of 1, 2, B, 6 and 5 (500 MHz, CDCl3,
room temp.)
2. Synthesis and Analysis of Complexes
The bis(benzyl) bis(bipyridyl) podand 1 was prepared as
As previously experienced at the upper rim of the ca-
previously reported.[7] The air-stable orange copper(I) com- lix[4]arene (complexes C and D) and assessed by a crystal
plex, 2, was synthesised by mixing stoichiometric amounts structure (complex C),[4f] the cobalt(II) chloride can be
of ligand 1 and Cu(CH3CN)4PF6 in CH3CN. It was ob- complexed by a bipyridine unit in a tetrahedral mode invol-
tained in a pure state with a yield of 90% after chromato- ving two chloride ions and the two bipyridyl nitrogen
graphy on alumina with CH2Cl2 as eluent. The ML stoichi- atoms.[10]
ometry was preliminarily determined by UV titration, with
The blue-green complex 3 was prepared by adding an
the appearance of the characteristic MLCT (Metal-to-Li- excess of CoCl2 to 1 in a mixture of CH3CN and CH2Cl2
gand Charge Transfer) band at 447 nm; the ε value of 5500 at room temperature; due to its good solubility in CH2Cl2,
dm3·molϪ1·cmϪ1, measured with a CH2Cl2 solution of 2, is 3 was easily separated from excess CoCl2 in a highly pure
similar to those of the parent complexes.[4b,4e] Electrospray form. The dinuclear nature of 3 was indicated by UV/Vis
mass spectrometry (positive mode, 60 V) showed the pres- spectroscopy, which showed the presence of the expected
ence of the monocharged 1:1 adduct [1 ϩ Cu]ϩ, charac- metal-centred transition at 658 cmϪ1, with a molar extinc-
terised by a base peak at 1257.7 amu, and elemental ana- tion coefficient of ca. 1000 dm3·molϪ1·cmϪ1, twice the value
1
lysis was consistent with the proposed formula. H NMR reported for complex C, and identical to that of complex
study of 2 (Figure 1) showed strong similitude with parent D. Elemental analysis was consistent with the formula
species,[4e] and with its picolyl analogue A,[8] for which the C82H88Co2Cl4N4O4. Electrospray mass spectrometry (posit-
racemic pro-helicoidal metal-centred structure was demon- ive mode, 252 V) showed notably the presence of the ex-
strated by X-ray analysis. More particularly, the helicoidal pected mono-charged species [1 ϩ 2 CoCl2 Ϫ Cl]ϩ at 1417.5
arrangement of the two bipyridine units was evident by the amu (10%), accompanied by the ‘‘decomplexed’’ species,
presence of an AB system at δ ϭ 5.00, 6.35, attributed to such as [1 ϩ CoCl2 Ϫ Cl]ϩ at 1287.5 amu (40%), [1 ϩ Na]ϩ
902
Eur. J. Inorg. Chem. 2002, 901Ϫ909

Calix[4]arene-Based Bipyridine Podand
FULL PAPER
at 1216.7 amu (100%), [1 ϩ H]ϩ at 1193.7 amu (60%), and and 295.5 nm (curves fϪi; 1.2Ϫ2.0 equiv. of NiCl2·6H2O),
by various fragmentation products. which correspond to the formation of the mono- and the
1
In the standard H NMR spectrum of 3 (δ ϭ 0Ϫ15), the dinuclear species, respectively. Attempts to isolate the for-
absence of some resonance signals confirmed the paramag- mer have failed until now.
netic nature of the [Co/bpy] subunit, as was previously ob-
served.[4f] Recording data in a larger frequency domain
(65000 Hz; δ ϭ 216 at 300 MHz, δ ϭ 130 at 500 MHz)
showed 11 new resonance signals that were correlated by a
COSY experiment (Figure 2): two groups of three singlets
integrating 2 H each at δ ϭ 72.93 (∆ν1/2 ϭ 32 Hz), 42.28
(∆ν1/2 ϭ 34 Hz), Ϫ6.75 (s, ∆ν1/2 ϭ 77 Hz), and δ ϭ 72.72
(s, ∆ν1/2 ϭ 25 Hz), 49.18 (s, ∆ν1/2 ϭ 28 Hz), Ϫ14.76 (s,
∆ν1/2 ϭ 21 Hz) were attributed to the bipyridyl groups; one
group of two singlets integrating 4 H each at δ ϭ Ϫ9.70
(s, ∆ν1/2 ϭ 40 Hz) and δ ϭ Ϫ3.05 (s, ∆ν1/2 ϭ 22 Hz) was
attributed to the Ar-CH2-Ar protons. No correlation was
found between the groups of bipyridyl aromatic protons
and signals corresponding to the OCH2 and CH3 groups.
Nevertheless, due to their chemical shifts and their integra-
tion values, the large singlets found at δ ϭ Ϫ42.49 (br. s,
∆ν1/2 ϭ 317 Hz, 4 H) and Ϫ22.60 (br. s, ∆ν1/2 ϭ 196 Hz, 6
H) were assigned to the latter, respectively. Finally, the
sharp singlet (∆ν1/2 ϭ 4 Hz) found at δ ϭ Ϫ1.72 and
integrating 18 H was assigned to two of the four tert-butyl
groups.
Figure 3. UV/Vis titration of 1 by NiCl2·6H2O [CH3CN/CH2Cl2
(95:5); aϪd: 0.0Ϫ0.8 equiv. of NiCl2·6H2O; fϪi: 1.2Ϫ2.0 equiv. of
NiCl2·6H2O]
The reaction of 1 with 2 equiv. of NiCl2·6H2O at room
temp., followed by evaporation of solvents, re-dissolution in
CHCl3 and precipitation with hexane, afforded 4 as a sal-
mon-pink microcrystalline solid. Elemental analysis was
consistent with the formula C82H88Cl4N4Ni2O4·0.5CHCl3.
Electrospray mass spectrometry (positive mode, 234 V)
showed, as for the cobalt complex 3, the presence of the
expected mono-charged species [1 ϩ 2 NiCl2 Ϫ Cl]ϩ at
1413.5, 1415.5, 1416.5, 1417.5, 1419.5 amu (10%), accom-
panied by the ‘‘decomplexed’’ species, such as [1 ϩ NiCl2
Ϫ Cl]ϩ at 1285.5, 1287.5 amu (30%), [1 ϩ Na]ϩ at 1216.7
amu (100%), [1 ϩ H]ϩ at 1193.7 amu (80%), and by various
fragmentation products. Expecting that, as for the cobalt
complex 3, the paramagnetic nature of the nickel(II) ion
should only influence the bipyridine unit resonance signals,
1
4 was analysed by NMR at 500 MHz. The H NMR spec-
trum, recorded in a large frequency domain (δ ϭ 0Ϫ85)
showed the presence of 18 resonance signals with ∆ν1/2
varying from 9 to 392 Hz. Among them, two sharp singlets
(∆ν1/2 ϭ 9 Hz) integrating 18 H each at δ ϭ 1.97 and 2.03
were attributed to the tert-butyl groups; four singlets integ-
rating 2 H each located at δ ϭ 58.22 (∆ν1/2 ϭ 46 Hz), 63.80
Figure 2. 2D COSY spectrum of cobalt complex 3 (500 MHz,
298 K, CDCl3)
(∆ν1/2 ϭ 38 Hz), 80.41 (∆ν1/2 ϭ 80 Hz), and 84.72 (∆ν1/2
ϭ
A preliminary study of the complexation of the nickel(II) 90 Hz) were suspected to be bipyridyl resonance signals. A
cation was conducted in solution by UV/Vis titration of 1 2D COSY experiment (Figure 4) confirmed this hypothesis,
with NiCl2·6H2O in CH3CN/CH2Cl2 (95:5) (Figure 3). The allowing us to build in two groups of three singlets at δ ϭ
new ligand-centred absorption band that appeared at 84.72 (∆ν1/2 ϭ 90 Hz), 58.22 (∆ν1/2 ϭ 46 Hz), 16.75 (∆ν1/2
318 nm upon complexation increased, up to exactly 2 equiv. ϭ 87 Hz), and δ ϭ 80.41 (∆ν1/2 ϭ 80 Hz), 63.80 (∆ν1/2
of the metal ion, confirming the formation of a dinuclear 38 Hz), 22.50 (∆ν1/2 ϭ 26 Hz). Another correlation was
complex. Two close isosbestic points (offset) were observed found between two signals located at δ ϭ 10.75 (s, ∆ν1/2
at 300.5 nm (curves aϪd; 0.0Ϫ0.8 equiv. of NiCl2·6H2O) 57 Hz) and 5.60 (s, ∆ν1/2 ϭ 50 Hz), integrating 4 H each,
ϭ
ϭ
Eur. J. Inorg. Chem. 2002, 901Ϫ909
903

J.-B. Regnouf-de-Vains et al.
FULL PAPER
which were attributed to the Ar-CH2-Ar groups (Figure 4, NMR spectrum (Figure 1) between δ ϭ 0 and 10, dis-
offset). The residual signals were not precisely assigned.
playing notably an AB system at δ ϭ 3.12, 4.48 (JAB ϭ
12.9 Hz) assigned to the Ar-CH2-Ar groups. Both benzyl
and bipyridyl methylene groups appear as singlets at δ ϭ
5.02 and 5.81, respectively, indicating the absence of con-
formational constraint on these pendant arms. All the res-
onance signals were attributed with the help of a COSY
experiment. 13C NMR Ar-CH2-Ar resonance signal was
found at δ ϭ 31.56, in the range accepted for the cone con-
formation.[11]
With the aim of preparing a mononuclear zinc(II) com-
plex displaying structural features equivalent to the above-
mentioned copper(I) and silver(I) complexes 2 and B, we
changed the chloride ions to the noncoordinating trifluoro-
methanesulfonate ion. UV/Vis titration of 1 by Zn(Tfo)2
(Tfo ϭ CF3SO3Ϫ) in CH2Cl2 resulted in the bathochromic
shift of the ligand-centred transition from 288 to 317 nm,
and confirmed the formation of the expected mononuclear
species. Complex 6 was thus prepared by mixing 1 and 1
equiv. of Zn(Tfo)2 in CH2Cl2 and methanol at room tem-
perature. Evaporation of the solvents and dissolution of the
residue in CHCl3, followed by filtration and addition of
hexane afforded 6 as a white precipitate, in a yield of 90%.
Electrospray mass spectrometry (positive mode, alcohol-
free CH2Cl2, ϩ90 V) showed the presence of the expected
mono-charged mononuclear species at 1405.7, 1409.6,
1410.7, and 1413.9 amu ([1 ϩ Zn ϩ Tfo]ϩ), accompanied
by a fragment resulting from the loss of one C6H5CH2O
group at 1301.8, 1303.8, 1304.8, and 1306.8 amu ([1 ϩ Zn
ϩ Tfo Ϫ C6H5CH2O ϩ H]ϩ); working at a lower voltage
(45 V) resulted in the appearance of a base peak at 628.5,
629.4, and 630.0 amu attributed to the doubly-charged spe-
cies ([1 ϩ Zn]2ϩ/2. Elemental analysis was consistent with
the formula C82H88N4O4·(CF3SO3)2·Zn·CHCl3. The two
Figure 4. 2D COSY spectrum of nickel complex 4 (500 MHz,
298 K, CDCl3)
Since zinc(II) accepts a tetrahedral geometry with 6,6Ј- Ar-CH2-Ar 13C NMR resonance signals located at δ ϭ
dimethyl-2,2Ј-bipyridine,[10] we attempted to prepare the di- 32.37 and 32.87 indicated that 6 was in a distorted cone
nuclear complex 5, in which, as for its cobalt and nickel conformation.[11]
A
1H NMR 2D COSY experiment al-
parents 3 and 4, each metallic centre should be coordinated lowed the full assignment of the resonance signals of 6. As
to one bipyridine unit and to two chloride ions. The com- for the tetrahedral species 2 and B (Figure 1), the Ar-CH2-
plexation of ZnCl2 by ligand 1 was studied by UV/Vis titra- Ar resonance signals appear as two AB systems at δ ϭ 2.67,
tion, which showed the presence of two close isosbestic 3.40 and 2.84, 4.02, indicating a distortion of the conic ca-
points at 299.4 and 303 nm. The two new ligand-centred lixarene platform; the benzyl methylene groups also appear
absorption bands that appeared at 310 and 321 nm upon as an AB system at δ ϭ 4.06, 4.21, resulting from an
addition of ZnCl2 increased, up to exactly 2 equiv. of metal environmental difference generated by the helicoidal com-
ion, confirming the formation of the expected dinuclear plex substructure. The latter is also characterised by a
species 5. The latter was prepared as a white microcrystal- strong AB system located at δ ϭ 5.55, 5.78, attributed to
line solid by mixing the ligand 1 and an excess of ZnCl2 in the OCH2-bpy groups. All attempts to obtain crystals suit-
MeOH and CH2Cl2 at room temp., followed by filtration able for a convenient X-ray analysis have failed until now.
of unchanged ZnCl2 and slow concentration of the filtrate.
In parallel, attempts to prepare, on the base of the results
Surprisingly, with regards to complexes 3 and 4, elec- obtained with zinc(II), the mononuclear cobalt(II) and
trospray mass spectrometry (positive mode, 80 V) gave poor nickel(II) species by anion metathesis were unsuccessful.
information on the complex composition, with the presence
On the other hand, the different experiments performed
of one partially ‘‘decomplexed’’ species at 1255.8, 1258.7, to obtain a di- or mononuclear copper(II) complex species
and 1259.8 amu [1 ϩ Zn2ϩ Ϫ Hϩ]ϩ, and the presence of a resulted in the slow partial to full formation of red cop-
fragment of ligand at 1032.9, 1033.8, and 1034.9 amu [1 ؊ per(I) species. This phenomenon had been previously ob-
2 (CH2C6H5) ϩ Naϩ]ϩ. Elemental analysis was consistent served, but as a spontaneous reaction, during the study of
with the formula C82H88Cl4N4O4Zn2·0.5CH2Cl2. Due to its
diamagnetism, complex 5 gave a perfectly well-resolved H ving an oxidisable substrate and a base in the presence of
A
[8] and was explained by an oxido reduction process invol-
1
904
Eur. J. Inorg. Chem. 2002, 901Ϫ909

Calix[4]arene-Based Bipyridine Podand
FULL PAPER
copper(II) and the bipyridyl calixarene podand. This par- creasing from 24.8(1)° for 3, to 31.65(7)° for 5 and 47.39(9)°
ticular reactivity is currently under investigation.
for 4. Distances from the metal ion to the mean plane of
˚
˚
each bipyridine unit vary from 0.006 A to 0.103 A, while
˚
˚
the chloride distances vary from 1.626 A to 2.311 A.
Distances and angles have been calculated around each
metal ion (Tables 1 and 2). The geometry is very similar
with a mean angle value NϪmetalϪN of 81.6°. Mean dis-
3. X-ray Crystal Structure Analyses
At the end of the above-mentioned investigations de-
veloped in solution, we obtained single crystals suitable for
X-ray analysis with the dinuclear cobalt, nickel and zinc
complexes 3, 4 and 5. In each case the results of the X-ray
crystal structure analyses confirmed that two divalent metal
ions are complexed by a podand unit in the expected, more
or less distorted, tetrahedral mode,[4f,10] with the participa-
tion of the two nitrogen atoms of each bipyridine unit and
two coordinating chloride ions.
˚
˚
tances metalϪN have values of 2.033 A in 3, 2.005 A in 4
˚
and 2.050 A in 5, while the mean value for metalϪCl is 2.21
˚
A for the 3 compounds.
Comparison of cobalt complex subunits in C and 3
shows a high similarity in the coordination mode; in 3, the
Co1 coordination appears less distorted than that of Co2
and that in C. A similar difference in distortion is also ob-
served between the two complex subunits in 4 and in 5.
In each compound, one of the benzyl groups (E) is always
found in the same position, in such a way that the benzene
ring is almost parallel to the corresponding phenolic ring
of the calixarene. The second benzyl group (F) is oriented
out of the cone (Figure 6).
In the study of the packing of the zinc complex 5, we can
note some πϪπ interactions between one ring of a bipyrid-
ine unit (B) and another one (D) of the macrocycle ob-
tained by a 21 axis (Figure 7). The same situation is found
in 3.
The study of the calixarene platform subunit shows that
the three compounds display a similar cone conformation.
The inclination angles versus the mean plane of the methyl-
ene groups are very similar: two of the phenolic rings are
near 90° (values between 90.8 and 98.5°) and the two others
carrying the bipyridine units lie outside (values between
129.9 and 135.7°; Figure 5, ORTEP view of nickel com-
plex 4).
The bipyridine units are very planar (χ2 from 0.01 to
0.08), but the angles between their planes are different, in-
Figure 5. ORTEP side-view and numbering scheme of complex 4 (carbon atoms 8, 9, 26, 225 and 226 are omitted for clarity)
Eur. J. Inorg. Chem. 2002, 901Ϫ909
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J.-B. Regnouf-de-Vains et al.
FULL PAPER
Table 1. Selected geometric parameters around the cobalt centres in complexes C and 3
C
3
Bond angles [°]
Cl2ϪCoϪCl3
N52ϪCoϪN6
N52ϪCoϪCl2
N52ϪCoϪCl3
N61ϪCoϪCl2
N61ϪCoϪCl3
118.4(9)
182.3(2)
119.6(2)
108.7(2)
112.0(2)
110.1(2)
Cl10ϪCo1ϪCl11
N27MϪCo1ϪN27F
N27MϪCo1ϪCl11
N27FϪCo1 ϪCl11
N27MϪCo1ϪCl10
N27FϪCo1ϪCl10
115.2(9)
82.3(3)
114.4(2)
111.7(2)
116.0(2)
112.9(2)
Cl20ϪCo2ϪCl21
119.3(1)
80.8(3)
119.2(2)
113.9(2)
110.1(2)
115.3(2)
N25BϪCo2ϪN25M
N25BϪCo2ϪCl20
N25BϪCo2ϪCl21
N25MϪCo2ϪCl20
N25MϪCo2ϪCl21
˚
Bond lengths [A]
CoϪCl2
CoϪCl3
CoϪN52
CoϪN61
2.2213(2)
2.222(2)
2.021(5)
2.027(6)
Co1ϪCl11
Co1ϪCl10
Co1ϪN27F
Co1ϪN27M
2.201(2)
2.225(2)
2.029(6)
2.015(6)
Co2ϪCl20
Co2ϪCl21
Co2ϪN25M
Co2ϪN25B
2.210(3)
2.212(3)
2.050(7)
2.036(6)
Table 2. Selected geometric parameters around the metal centres in
complexes 4 and 5
4
5
Bond angles [°]
Cl1BϪNi1ϪCl1A
N26BϪNi1ϪN25A
N26BϪNi1ϪCl1B
N25AϪNi1ϪCl1B
N26BϪNi1ϪCl1A
N25AϪNi1ϪCl1A
Cl2BϪNi2ϪCl2A
N27BϪNi2ϪN27A
N27BϪNi2ϪCl2B
N27AϪNi2ϪCl2B
N27BϪNi2ϪCl2A
N27AϪNi2ϪCl2A
118.6(5)
82.0(2)
126.7(1)
123.1(1)
98.0(1)
100.1(1)
133.0(7)
82.1(2)
110.5(1)
109.2(1)
105.3(1)
104.9(1)
Cl3ϪZn1ϪCl4
116.95(5)
81.6(2)
N261ϪZn1ϪN266
N261ϪZn1ϪCl4
N261 ϪZn1ϪCl3
N266ϪZn1ϪCl4
N266ϪZn1ϪCl3
Cl5ϪZn2ϪCl6
N281ϪZn2ϪN286
N281ϪZn2ϪCl6
N281ϪZn2ϪCl5
N286ϪZn2ϪCl6
N286ϪZn2ϪCl5
114.9(1)
110.7(1)
120.9(1)
106.5(1)
118.01(6)
80.9(2)
105.7(1)
116.4(1)
113.6(1)
116.2(1)
Figure 7. Interactions between rings B and D in complex 5 (tert-
˚
Bond lengths [A]
butyl groups and chlorine atoms were omitted for clarity
Ni1ϪCl1A
Ni1ϪCl1B
Ni1ϪN25A
Ni1ϪN26B
Ni2ϪCl2A
Ni2ϪCl2B
Ni2ϪN27A
Ni2ϪN27B
2.240(1)
2.180(2)
2.010(4)
2.003(4)
2.228(1)
2.188(2)
2.002(4)
2.003(4)
Zn1ϪCl3
Zn1ϪCl4
Zn1ϪN261
Zn1ϪN266
Zn2ϪCl5
Zn2ϪCl6
Zn2ϪN281
Zn2ϪN286
2.222(1)
2.196(1)
2.051(4)
2.038(4)
2.204(2)
2.236(2)
2.070(4)
2.041(4)
The corresponding calixarenes are obtained both by the
centre of symmetry and by translation along b axis (Fig-
ure 8).
Figure 8. Interactions between the bipyridine units A and B, and
C and D in nickel complex 4 (solvent atoms, tert-butyl groups and
chlorine atoms are omitted for clarity)
Figure 6. Side views of complex 4 and labelling of pendant bipyri-
dyl and benzyl arms[14]
Each complex crystallises with solvents which are not
shown in the figures: 4 with three molecules of toluene, 3
The nickel complex 4, which crystallises in the triclinic with one molecule of dichloromethane, and 5 with two mo-
system, shows interactions between bipyridine units A and lecules of dichloromethane and two of ethanol. For the lat-
B on one part, and pyridine rings C and D on another part. ter, one of the ethanol molecules displays a short contact
906
Eur. J. Inorg. Chem. 2002, 901Ϫ909

Calix[4]arene-Based Bipyridine Podand
FULL PAPER
(pos.
mode):
m/z
ϭ
1255.6
[1
ϩ
CuI]ϩ.
with a chlorine atom of one dichloromethane molecule
(Cl···O ϭ 3.208 A).
˚
C82H88CuF6N4O4P·0.8CH2Cl2 (1470.09): calcd. C 68.30, H 6.08,
N 3.77; found C 68.06, H 6.03, N 3.86.
Dinuclear Cobalt(II) Chloride Complex 3: A solution of 0.016 g of
CoCl2 (1.26 10Ϫ4 mol) in 5 mL of acetonitrile was added to a solu-
tion of 0.05 g of 1 (4.2 10Ϫ5 mol) in 10 mL of CH2Cl2. The resulting
blue-green solution was stirred at room temp. during 1 h and then
concentrated to dryness. The residue was treated with 5 mL of
CH2Cl2 and the excess of CoCl2 was removed by filtration. Slow
concentration of the filtrate gave blue-green crystals of 3 (0.060 g,
Conclusion
The bipyridyl-containing calix[4]arene podand 1 de-
scribed in this report shows interesting versatile complexing
properties towards various common transition metal cat-
ions, giving in all cases complexes with tetrahedral coor-
dination geometry. Depending on the nature of the cation,
but also of the coordinating ability of the counter-anion,
these complexes are of the L/M or L/M2 stoichiometry, as
demonstrated by UV/Vis spectroscopy, high resolution
NMR spectroscopy and X-ray diffraction analysis. This ver-
˜
98%). M.p. 235 °C. IR: ν ϭ 1570, 1601 (CϪN), 2956 (CϪH). UV/
Vis (CH2Cl2): λ ϭ 317 (30700), 568 (550), 658 (1000). 1H NMR
(500 MHz, CDCl3): δ ϭ Ϫ42.49 (br. s, ∆ν1/2 ϭ 317 Hz, 4 H,
OCH2bpy), Ϫ22.60 (br. s, ∆ν1/2 ϭ 196 Hz, 6 H, Mebpy), Ϫ14.76
(s, ∆ν1/2 ϭ 21 Hz, 2 H, bpy), Ϫ9.70 (s, ∆ν1/2 ϭ 40 Hz, 4 H, 2 Ar-
CH2-Ar), Ϫ 6.75 (s, ∆ν1/2 ϭ 77 Hz, 2 H, bpy), Ϫ3.05 (s, ∆ν1/2
ϭ
satile behaviour is currently the subject of competitive ex- 22 Hz, 4 H, 2 Ar-CH2-Ar), Ϫ1.72 (s, ∆ν1/2 ϭ 4 Hz, 18 H, Me3C),
Ϫ0.13 (s, ∆ν1/2 ϭ 6 Hz, 18 H, Me3C), 1.75 (s, ∆ν1/2 ϭ 6 Hz, 4 H,
ArH), 1.78 (s, ∆ν1/2 ϭ 6 Hz, 4 H, ArH), 4.17 (s, ∆ν1/2 ϭ 18 Hz, 4
H, 2 OCH2C6H5), 8.63 (s, ∆ν1/2 ϭ 22 Hz, 4 H, C6H5), 9.77 (s, ∆ν1/
traction studies, which necessitates developing in parallel
the synthesis of the corresponding heterodinuclear com-
plexes.
ϭ 12 Hz, 2 H, C6H5), 11.38 (s, ∆ν1/2 ϭ 22 Hz, 4 H, C6H5), 42.28
2
(s, ∆ν1/2 ϭ 34 Hz, 2 H, bpy), 49.18 (s, ∆ν1/2 ϭ 28 Hz, 2 H, bpy),
72.72 (s, ∆ν1/2 ϭ 25 Hz, 2 H, bpy), 72.93 (s, ∆ν1/2 ϭ 32 Hz, 2 H,
bpy). ES-MS (pos. mode, 252 V): m/z ϭ 1417.5 [1 ϩ 2 (CoCl2) Ϫ
ClϪ]ϩ, 1288.5 [1 ϩ CoCl2 Ϫ ClϪ]ϩ, 1215.7 [1 ϩ Na]ϩ, 1193.7 [1 ϩ
H]ϩ. C82H88Cl4Co2N4O4 (1453.32): calcd. C 67.77, H 6.10, N 3.86;
found C 68.00, H 6.25, N 3.65.
Experimental Section
General: Melting points (°C, uncorrected values) were determined
with an Electrothermal 9100 (capillary apparatus). 1H and 13C
NMR spectra were recorded with a Bruker AM 300 or DRX 300
and DRX 500 (CDCl3, TMS as internal standard, chemical shifts
in ppm). Mass spectra (electrospray, ES) were recorded with a Plat-
form Micromass apparatus at the Service Central d’Analyse du
CNRS, Solaize. Infrared spectroscopy was performed with a Matt-
son 5000 FT apparatus (KBr, ν in cmϪ1) and UV spectra were
recorded with a Shimadzu UV 2401 PC or a SAFAS UV mc2 ap-
paratus, λmax in nm, ε in dm3·molϪ1·cmϪ1. Elemental analyses were
Dinuclear Nickel(II) Chloride Complex 4: A solution of 0.020 g of
1 (1.67 10Ϫ5 mol) and 0.0081 g of NiCl2·6H2O (3.35 10Ϫ5 mol) in
a mixture of CH2Cl2 (1 mL), acetonitrile (10 mL) and methanol (1
mL) was stirred at room temp. during 1 h. The resulting salmon-
pink solution was concentrated to dryness; the residue was dis-
solved in CHCl3 and the addition of 10 mL of hexane resulted in
the precipitation of 4 as a pink microcrystalline solid (0.017 g;
´
performed at the Service Central de Microanalyse, Ecole Superie-
˜
71%). M.p. 295 °C. IR: ν ϭ 2957 (CH), 1574, 1603 (CϪN). UV/
Vis (CH2Cl2): λ ϭ 310 (40200), 488 (325). 1H NMR (500 MHz,
ure de Chimie, Montpellier. MachereyϪNagel TLC plates were
used for chromatography analysis (SiO2, Polygram SIL G/UV254,
ref. no. 805021). All commercially available products were used
without further purification unless otherwise specified.
CDCl3): δ ϭ 1.97 (s, ∆ν1/2 ϭ 9 Hz, 18 H, Me3C), 2.03 (s, ∆ν1/2
9 Hz, 18 H, Me3C), 5.60 (s, 4 H, Ar-CH2-Ar), 10.75 (s, ∆ν1/2
57 Hz, 4 H, Ar-CH2Ar), 16.75 [s, ∆ν1/2 ϭ 87 Hz, 2 H, bpy(1)], 22.50
[s, ∆ν1/2 ϭ 26 Hz, 2 H, bpy(2)], 58.22 [s, ∆ν1/2 ϭ 46 Hz, 2 H,
ϭ
ϭ
Mononuclear Copper(I) Hexafluorophosphate Complex 2: A solu-
tion of 0.0156 g of Cu(CH3CN)4PF6 (4.2 10Ϫ5 mol) in 5 mL of
acetonitrile was added to a suspension of 0.05 g of 1 (4.2 10Ϫ5 mol)
in 20 mL of acetonitrile. Upon complexation, 1 was dissolved, giv-
ing an orange-coloured solution. The solvent was evaporated to
dryness and the residue was chromatographed (Al2O3, CH2Cl2) to
give 2 (0.055 g, 90%). Orange powder. M.p. 308 °C. IR: ν˜ ϭ 1570
(CϪN), 2960 (CϪH). UV/Vis (CH2Cl2): λ ϭ 266 (29900), 302
(34700), 447 (5500, MLCT). 1H NMR (300 MHz, CDCl3): δ ϭ
0.76 (s, 18 H, Me3C), 1.34 (s, 18 H, Me3C), 1.85 (s, 6 H, Mebpy),
2.58, 3.75 (‘‘q’’, AB, JAB ϭ 13.3, 4 H, Ar-CH2-Ar), 2.78, 3.53 (‘‘q’’,
bpy(1)], 63.80 [s, ∆ν1/2 ϭ 38 Hz, 2 H, bpy(2)], 80.41 [s, ∆ν1/2
80 Hz, 2 H, bpy(2)], 84.72 [s, ∆ν1/2 ϭ 90 Hz, 2 H, bpy(1)],1.72 (s,
∆ν1/2 ϭ 28 Hz, 6 H), 5.32 (s, 4 H), 5.67 (s, 4 H), 6.25 (s, ∆ν1/2
ϭ
ϭ
16 Hz, 2 H), 6.77 (s, ∆ν1/2 ϭ 28 Hz, 4 H), 8.60 (s, ∆ν1/2 ϭ 14 Hz,
4 H), 8.94 (s, ∆ν1/2 ϭ 12 Hz, 4 H), 26.82 (s, ∆ν1/2 ϭ 392 Hz, 4 H)
(Mebpy, OCH2C6H5, C6H5, ArH, OCH2bpy). ES-MS (pos. mode,
234 V): m/z ϭ 1417.5 [1 ϩ 2 (NiCl2) Ϫ ClϪ]ϩ, 1287.5 [1 ϩ (NiCl2)
Ϫ
ClϪ]ϩ, 1215.7 [1 Na]ϩ. C82H88Cl4N4Ni2O4·0.5CHCl3
ϩ
(1512.52): calcd. C 65.51, H 5.90, N 3.70; found C 65.48, H 6.15,
N 3.64.
AB, JAB ϭ 12.6, 4 H, Ar-CH2-Ar), 3.82, 4.01 (‘‘q’’, AB, JAB ϭ 11.5, Dinuclear Zinc(II) Chloride Complex 5: A solution of 0.030 g of
4 H, OCH2C6H5), 5.00, 6.35 (‘‘q’’, AB, JAB ϭ 12.9, 4 H,
OCH2bpy), 6.22, 6.30 (AB, JAB ϭ 2.0, 4 H, ArH), 6.47 (dd, J ϭ
ZnCl2 (22.0 10Ϫ5 mol) in 5 mL of methanol was added to a solution
of 0.060 g of 1 (5.0 10Ϫ5 mol) in 10 mL of CH2Cl2. The solution
7.7 J ϭ 1.4, 4 H, C6H5), 7.02, 7.09 (AB, JAB ϭ 2.0, 4 H, ArH), was stirred at room temp. during 1 h, and the excess of ZnCl2 which
7.06Ϫ7.29 (m, 6 H, C6H5), 7.39 (d, J ϭ 7.7, 4 H, bpy), 7.93 (t, J ϭ
8.1, 2 H, bpy), 8.16 (t, J ϭ 8.1, 2 H, bpy), 8.19 (d, J ϭ 8.1, 2 H,
bpy), 8.44 (d, J ϭ 8.1, 2 H, bpy). 13C NMR (75 MHz, CDCl3):
δ ϭ 23.7 (Mebpy), 31.8, 32.4 (Ar-CH2-Ar), 31.1, 31.7 (Me3C), 33.6, (36500). H NMR (500 MHz, CD2Cl2): δ ϭ 0.93 (s, 18 H, Me3C),
34.2 (Me3C), 77.4 (OCH2C6H5), 79.3 (OCH2bpy), 119.8, 121.9, 1.38 (s, 18 H, Me3C), 3.05 (s, 6 H, Mebpy), 3.12, 4.48 (‘‘q’’, AB,
124.1, 124.54, 125.50, 126.7, 126.9, 127.8, 127.9, 128.9, 138.7, 139.0 JAB ϭ 12.9, 8 H, Ar-CH2-Ar), 5.02 (s, 4 H, OCH2C6H5), 5.81 (s, 4
(aromatic CH), 131.1, 131.4, 134.8, 135.8, 137.0, 144.5, 145.9, H, OCH2bpy), 6.60 (s, 4 H, ArH), 7.11Ϫ7.22 (m, 10 H, C6H5), 7.21
precipitated was removed by filtration. Slow concentration of the
filtrate afforded 5 as white crystals (0.068 g, 90%). M.p. 245 °C. IR:
˜
ν ϭ 1576, 1601 (CϪN). UV/Vis (CH2Cl2): λ ϭ 321 (32400), 310
1
151.96, 151.98, 152.1, 154.0, 157.7, 157.8 (aromatic C). ES-MS
(s, 4 H, ArH), 7.64 (d, J ϭ 8.1, 2 H, bpy), 7.67 (d, J ϭ 7.4, 2 H,
Eur. J. Inorg. Chem. 2002, 901Ϫ909
907

J.-B. Regnouf-de-Vains et al.
FULL PAPER
bpy), 7.71 (t, J ϭ 7.7, 2 H, bpy), 7.96 (d, J ϭ 8.1, 2 H, bpy), 8.11
matic CH), 128.05, 128.2, 131.2, 131.3, 134.8, 135.8, 136.8, 145.3,
(t, J ϭ 7.9, 2 H, bpy), 9.24 (d, J ϭ 7.9, 2 H, bpy). 13C NMR 147.1, 148.9, 149.6, 152.0, 153.7, 159.9, 161.0 (aromatic C). ES-MS
(125.75 MHz, CD2Cl2): δ ϭ 24.7 (Mebpy), 31.4, 31.8 (Me3C), 31.6 (pos. mode, 90 V): m/z ϭ 1405.7, 1409.6, 1410.7, 1413.9 [1 ϩ
(Ar-CH2-Ar), 34.1, 34.4 (Me3C), 75.7 (OCH2C6H5), 78.9 Zn(Tfo)2 Ϫ TfoϪ]ϩ; (45 V): m/z ϭ 628.5, 629.4, 630.0 [1 ϩ Zn]2ϩ
/
(OCH2bpy), 119.3, 120.0, 125.2, 126.88, 126.94, 127.7, 128.2, 128.4,
2. C84H88F6N4O10S2Zn·CHCl3 (1676.55): calcd. C 60.89, H 5.35,
130.6, 142.0 (aromatic CH), 132.6, 134.9, 137.1, 145.5, 146.9, 147.9, N 3.34; found C 60.80, H 5.62, N 3.38.
149.2, 150.7, 154.8, 160.2, 160.9 (aromatic C). ES-MS (pos. mode,
80 V): m/z ϭ 1255.8, 1258.7, 1259.8 [1 ϩ Zn2ϩ Ϫ Hϩ]ϩ, 1032.9,
X-ray Crystallographic Study of Complexes 3, 4 and 5: The data
were collected with a Nonius Kappa CCD diffractometer using
monochromated Mo-Kα radiation. Structures were solved by direct
1033.8,
1034.9
[1
؊
2
CH2C6H5
ϩ
Naϩ]ϩ.
C82H88Cl4N4O4Zn2·0.5CH2Cl2 (1508.69): calcd. C 65.68, H 5.95,
N 3.71; found C 65.63, H 6.18, N 3.82.
methods and refined using full-matrix least squares with
[12]
SHELXS97
and SHELXL97 programmes.[13] All non-H atoms
Mononuclear Zinc(II)trifluoromethanesulfonate Complex 6: A solu-
tion of 0.019 g of Zn(CF3SO3)2 (5.0 10Ϫ5 mol) in 10 mL of CH2Cl2/
methanol was added to a solution of 0.060 g of 1 (5.0 10Ϫ5 mol) in
20 mL of CH2Cl2. The solution was stirred at room temp. during
1 h, and the solvent was evaporated to dryness. The residue was
dissolved in 4 mL of CHCl3 and 20 mL of hexane was added,
affording 6 as a white precipitate (0.076 g, 90%). M.p. 202 °C. UV/
were refined anisotropically. Hydrogen atoms were calculated at
their idealised positions and refined isotropically riding on previous
atoms. Details for the experimental conditions, cell data, structure
and refinement data are given in Table 3. CCDC-167144 (3), -
167143 (4) and -167145 (5) contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge at www.ccdc.cam.ac.uk/conts/retrieving.html or from the
Cambridge Crystallographic Data Centre, 12, Union Road, Cam-
bridge CB2 1EZ, UK [Fax: (internat.) ϩ 44-1223/336-033; E-mail:
deposit@ccdc.cam.ac.uk].
1
Vis (CH2Cl2): λ ϭ 317 (31700). H NMR (300 MHz, CDCl3): δ ϭ
0.76 (s, 18 H, Me3C), 1.34 (s, 18 H, Me3C), 1.91 (s, 6 H, Mebpy),
2.67, 3.40 (‘‘q’’, AB, JAB ϭ 12.9, 4 H, Ar-CH2-Ar), 2.84, 4.02 (‘‘q’’,
AB, JAB ϭ 13.6, 4 H, Ar-CH2-Ar), 4.06, 4.21 (‘‘q’’, AB, JAB ϭ 11.8,
4 H, OCH2C6H5), 5.55, 5.78 (‘‘q’’, AB, JAB ϭ 14.0, 4 H,
OCH2bpy), 6.24 (s, 4 H, ArH), 6.48 (d, J ϭ 7, 4 H, C6H5), 7.09(s,
4 H, ArH), 7.04Ϫ7.17 (m, 6 H, C6H5), 7.60 (d, J ϭ 7.7, 2 H, bpy),
7.62 (d, J ϭ 7.7, 2 H, bpy), 8.18 (t, J ϭ 7.9, 2 H, bpy), 8.36 (t, J ϭ
7.9, 2 H, bpy), 8.60 (d, J ϭ 8.1, 2 H, bpy), 8.81 (d, J ϭ 8.1, 2 H,
Acknowledgments
bpy). 13C NMR (75 MHz, CDCl3): δ ϭ 23.7 (Mebpy), 31.4, 32.0 We are grateful to the MRES for financial support, especially J.-O.
(Me3C), 32.4, 32.9 (Ar-CH2-Ar), 33.9, 34.6 (Me3C), 78.1 D. for a PhD fellowship; to SAFAS (Monaco) and BRUKER S.
(OCH2C6H5), 78.2 (OCH2bpy), 122.2, 124.4, 124.6, 125.0, 126.2,
128.0, 128.5, 128.6, 128.8, 129.2, 129.5, 130.0, 144.1, 144.6 (aro-
A. for UV spectroscopy and WinNMR facilities, respectively. The
authors thank Mrs. Nicole Marshall for correcting the manuscript.
Table 3. Crystal data and structure refinement of 3, 4 and 5
3
4
5
Empirical formula
Formula mass
Temperature [K]
C83H90Cl8.5Co2N4O4
1538.15
293
C103H112Cl9N4O4Ni2
C87H102Cl7N4O6Zn2
1685.63
123
1729.19
293
triclinic, P1
¯
Crystal system, space group
Unit cell dimensions
monoclinic, C2/c
monoclinic, C2/c
˚
a [A]
45.852(9)
15.054(3)
23.798(5)
11.691(2)
17.225(3)
24.510(5)
48.501(9)
14.798(3)
24.082(5)
˚
b [A]
˚
c [A]
α [°]
β [°]
γ [°]
90
91.78(3)
90
16419(6)
92.94(3)
94.08(3)
105.98(3)
4719.8(16)
90
92.019(3)
90
17273.2(4)
8
1.291
0.825
883
3
˚
V [A ]
Z
8
2
Dcalcd. [MgmϪ3
]
1.244
0.648
804
1.217
0.564
914
Absorption coefficient [mmϪ1
F(000)
]
Crystal size [mm]
θ range for data collection [°]
Limiting indices
0.35 ϫ 0.30 ϫ 0.25
2.07 to 25.63
0 Յ h Յ 50
0 Յ k Յ 18
Ϫ27 Յ l Յ 27
12921/12921
0.8547 and 0.8049
12921/0/892
0.961
0.35 ϫ 0.30 ϫ 0.04
2.83 to 28.16
0 Յ h Յ 15
Ϫ21 Յ k Յ 21
Ϫ31 Յ l Յ 31
18423/18423
0.9778 and 0.8270
18423/1/1041
0.952
0.44 ϫ 0.30 ϫ 0.18
1.02 to 23.26
0 Յ h Յ53
Ϫ16 Յ k Յ 16
Ϫ26 Յ l Յ 26
117262/12367
0.866 and 0.712
12367/2/964
1.080
Reflections collected/unique
Max./min. transmission
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I Ͼ 2σ(I)]
R indices (all data)
Densities (max./min.) [e·A
R1 ϭ 0.0882, wR2 ϭ 0.2433
R1 ϭ 0.1731, wR2 ϭ 0.2960
0.894 and Ϫ1.084
R1 ϭ 0.0748, wR2 ϭ 0.1362
R1 ϭ 0.1907, wR2 ϭ 0.1669
0.534 and Ϫ0.520
R1 ϭ 0.0620, wR2 ϭ 0.1506
R1 ϭ 0.0798, wR2 ϭ 0.1590
1.00 and Ϫ0.82
Ϫ3
˚
]
908
Eur. J. Inorg. Chem. 2002, 901Ϫ909

Calix[4]arene-Based Bipyridine Podand
FULL PAPER
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´
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