Synthesis and structure of self-complementary {2}-metallacryptates and their linear or meandering infinite arrangements in the solid state

Article abstract of DOI:10.1002/ejic.200700579

Reaction of bis(1,3-diketone) H₂L¹ in the presence of cesium acetate with magnesium acetate yielded crystalline one-dimensional coordination polymer rac-(2)_n. The {2}-metallacryptand core [Mg ₂(L¹)

Full text of DOI:10.1002/ejic.200700579

FULL PAPER
DOI: 10.1002/ejic.200700579
Synthesis and Structure of Self-Complementary {2}-Metallacryptates and
Their Linear or Meandering Infinite Arrangements in the Solid State[‡]
Rolf W. Saalfrank,*[a] Nicolai Mooren,[a] Andreas Scheurer,[a] Harald Maid,[a]
Frank W. Heinemann,[a] Frank Hampel,[b] and Walter Bauer[b]
Dedicated to Professor Herbert Mayr on the occasion of his 60th birthday
Keywords: Metallacryptate / Coordination polymers / O ligands / X-ray diffraction / Chirality
Reaction of bis(1,3-diketone) H2L1 in the presence of cesium
acetate with magnesium acetate yielded crystalline one-di-
mensional coordination polymer rac-(2)n. The {2}-metal-
lacryptand core [Mg2(L1)3]2– is composed of two magnesium
H2L2 instead of methyl-substituted H2L1 with cesium or ru-
bidium acetate and magnesium, cobalt or zinc acetate
yielded the meandering polymer meso-{[({M1ʚ[(∆,∆)-M2
-
2
(L2)3]}M1end)({M1ʚ[(Λ,Λ)-M22(L2)3]}M1side)][({M1ʚ[(Λ,Λ)-
M22(L2)3]}M1end)({M1ʚ[(∆,∆)-M22(L2)3]}M1side)]}n [meso-(3)n]
(M1 = Cs+, Rb+; M2 = Mg2+, Co2+, Zn2+). In this case, the {2}-
metallacryptates {M1ʚ[(∆,∆/Λ,Λ)-M22(L2)3]}– are linked by
only one cesium ion end-on to give the fragments meso-
[({M1ʚ[(∆,∆)-M22(L2)3]}M1end)({M1ʚ[(Λ,Λ)-M22(L2)3]}M1side)],
which are connected by the second cesium ions side-on. The
one-dimensional meander strands of isostructural meso-(3)n
are packed in the crystal in parallel. Reaction of 4 equiv. of
zinc acetate and 1 equiv. of cesium or rubidium acetate with
2 equiv. of H2L2 afforded the {M1ʚ[Zn2(L2)2OAc]} cryptates
4a,b (M1 = Cs+, Rb+).
centres linked through three bis(1,3-diketo) dianions (L1)2–
.
These {2}-metallacryptands are homochiral with either (∆,∆)-
fac or (Λ,Λ)-fac stereochemistry at the magnesium centres,
and they are capable to host a cesium ion in the cavity.
Charge compensation of the thus formed {2}-metallacryp-
tates {Csʚ[Mg2(L1)3]}– is achieved through extra external ce-
sium ions to give the neutral self-complementary building
blocks [{Csʚ[(∆,∆)/(Λ,Λ)-Mg2(L1)3]}Cs], which aggregate
end-on across the external cesium ions to give the homo-
chiral one-dimensional strings [{Csʚ[(∆,∆)-Mg2(L1)3]}Cs]n [∆-
(2)n] and [{Csʚ[(Λ,Λ)-Mg2(L1)3]}Cs]n [Λ-(2)n], which are
packed in the crystal in alternating homochiral layers. How-
ever, reaction of bulkier phenyl-substituted bis(1,3-diketone)
(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2007)
Introduction
In earlier work, we demonstrated that hexacoordinate
nickel(II) in the presence of cesium ions reacts with bis(1,3-
diketo) dianion (L1)2– to yield the neutral {2}-metallacrypt-
ate [{Csʚ[Ni2(L1)3]}Cs] with either (∆,∆)-fac or (Λ,Λ)-fac
stereochemistry at the nickel centres. These building blocks
are self-complementary and aggregate across the external
cesium ions alternately end-on to yield in the solid state the
one-dimensional coordination polymer meso-[({Csʚ[(∆,∆)-
Ni2(L1)3]}Cs)({Csʚ[(Λ,Λ)-Ni2(L1)3]}Cs)]n [meso-(1)n] (Fig-
ure 1).[2]
[‡] Chelate Complexes, Part 37. Part 36: Ref.[1]
[a] Institut für Anorganische Chemie, Universität Erlangen-
Nürnberg
Egerlandstraße 1, 91058 Erlangen, Germany
Fax: +49-9131-85-27396
E-mail: saalfrank@chemie.uni-erlangen.de
[b] Institut für Organische Chemie, Universität Erlangen-Nürnberg
91054 Erlangen, Germany
Figure 1. Schematic presentation of the repeating unit of crystalline
1D coordination polymer meso-(1)n (top) and the POVRAY
presentation of the repeating unit of the molecular structure of
meso-(1)n (bottom).
Eur. J. Inorg. Chem. 2007, 4815–4822
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
4815

R. W. Saalfrank et al.
FULL PAPER
Results and Discussion
In the course of our ongoing studies on supramolecular
coordination chemistry with nickel(II)[2] and copper(II),[2–4]
we focused on the development of new oligonuclear com-
plexes by self-assembly[5] with the bis(1,3-diketo) dianion
(L1)2–. To this end, we treated H2L1 with magnesium ace-
tate in the presence of cesium acetate in methanol. As in
the nickel case, the cesium ions function as templates for
the formation of crystalline one-dimensional coordination
polymer rac-(2)n (Scheme 1). Cuboids obtained by vapour
diffusion of diethyl ether into a solution of the reaction
product in acetonitrile were subjected to X-ray crystal
analysis, which revealed that ∆/Λ-(2)n crystallizes in the tri-
[6]
¯
clinic space group P1 (Table 1). In ∆/Λ-(2)n, the {2}-
metallacryptand [Mg2(L1)3]2– core is composed of two mag-
nesium centres linked through three hexadentate cate-
cholate-spacered bis(1,3-diketo) dianions (L1)2–. Therefore,
each magnesium ion is coordinated octahedrally by six di-
keto oxygen donors. The resulting {2}-metallacryptands are
homochiral with either (∆,∆)-fac or (Λ,Λ)-fac stereochemis-
try at the magnesium centres and capable to host a cesium
ion in the cavity, which is coordinated by six carbonyl and
six catecholate oxygen donors each. Charge compensation
of the thus formed enantiomers {Csʚ[(∆,∆)/(Λ,Λ)-Mg2-
(L1)3]}– is achieved through extra external cesium ions to
give the neutral self-complementary building blocks
[{Csʚ[(∆,∆)/(Λ,Λ)-Mg2(L1)3]}Cs]. However, contrary to
meso-(1)n, these building blocks aggregate in the solid state
end-on across the external cesium ions to give the homo-
chiral strings [{Csʚ[(∆,∆)-Mg2(L1)3]}Cs]n [∆-(2)n] and
[{Csʚ[(Λ,Λ)-Mg2(L1)3]}Cs]n [Λ-(2)n],[6] which are packed in
the crystal in alternating homochiral layers (Figure 2). In
∆/Λ-(2)n, the coupling external cesium ions are coordinated
by two sets of three peripheral carbonyl oxygen donors and
two acetonitrile molecules. An additional noncoordinating
acetonitrile molecule per monomer unit, trapped in the
Scheme 1. Synthesis and schematic presentation of the repeating
units of the homochiral strings ∆-(2)n and Λ-(2)n [= rac-(2)n].
Figure 2. Stereo presentation (POVRAY) of a layer of Λ-(2)n in the
crystal together with the coordinating acetonitrile solvent mole-
cules. Mg grey, Cs light grey.
crystal, leads to the final overall stoichiometry ∆/Λ- In meso-(3e)n, two enantiomers {Csʚ[(∆,∆/Λ,Λ)-Co2-
(2·3MeCN)n. Therefore, the stereogenic metal centres are (L2)3]}– are linked by only one cesium ion end-on and a
controlled, simply by varying hexacoordinate NiII in meso- second one is coordinated side-on to connect these
(1)n to MgII in ∆/Λ-(2)n.
units to finally give meso-{[({Csʚ[(∆,∆)-Co2(L2)3]}Csend)-
To suppress the formation of self-complementary mono- ({Csʚ[(Λ,Λ)-Co2(L2)3]}Csside)][({Csʚ[(Λ,Λ)-Co2(L2)3]}-
mers and their aggregation in the solid state by making the Csend)({Csʚ[(∆,∆)-Co2(L2)3]}Csside)]}n [meso-(3e)n]. There-
external pockets of the cryptates too small to host the exter- fore, the Csend links two enantiomers {Csʚ[(∆,∆/Λ,Λ)-
nal cesium ions, we used H2L2 with bulkier phenyl groups Co2(L2)3]}–, whereas the Csside links the meso-[({Csʚ[(∆,∆)-
instead of H2L1 with methyl substituents at the end. For Co2(L2)3]}Csend)({Csʚ[(Λ,Λ)-Co2(L2)3]}Csside)] fragments
that purpose, the reaction of stoichiometric amounts of across their homochiral {2}-metallacryptate halves. The ex-
H2L2, cesium or rubidium acetate and magnesium, cobalt planation for the formation of this structure is the fact that
or zinc acetate in acetonitrile was performed, and we iso- when an external cesium splits the {2}-metallacryptate
lated microcrystalline materials after vapour diffusion of di- building block at one end, the pocket at the other end is
ethyl ether into a solution of the reaction products compressed and incapable to host another Csend. The Csside
(Scheme 2).
ion is coordinated to eight oxygen donors of four ligands
Single crystals obtained for meso-(3b,e)n were subjected (L2)2– (one carbonyl oxygen donor of one ligand and one
to X-ray crystal analyses (Table 1).[6] According to these carbonyl oxygen donor together with two catecholate oxy-
analyses, meso-(3b,e)n are isostructural and crystallize in the gen donors of another ligand of one cryptate each) and to
monoclinic space group P21/n. Therefore, only the structure two acetonitrile molecules. The meander strands of iso-
of meso-(3e)n is discussed in detail. Contrary to our expec- structural meso-(3b,e)n are packed in the crystal in parallel.
tation, a strand meso-(3e)n was obtained in the solid state. The repetitive unit of the structure in the crystal is therefore
4816
www.eurjic.org
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2007, 4815–4822

Synthesis and Structure of Self-Complementary {2}-Metallacryptates
Scheme 2. Synthesis and schematic presentation of the complex repeating unit of infinite one dimensional meander meso-(3)n.
rather complex. Figure 3 exemplarily exhibits the stereo
presentation of the repeating unit of meso-(3e)n. The stereo
view of Figure 4 presents only the metal centres of two
strands of meso-(3e)n.
Figure 4. Simplified stereo presentation (POVRAY) of meander
Figure 3. Stereo presentation (POVRAY) of the repeating unit of
meso-(3e)n in the crystal without solvent molecules. Co grey, Cs
light grey.
meso-(3e)n. The Csʚ, Csend and Co centres are connected by lines
and are arranged in angles, linked by the Csside ions. Co grey, Cs
light grey.
Eur. J. Inorg. Chem. 2007, 4815–4822
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4817

R. W. Saalfrank et al.
FULL PAPER
Surprisingly, when stoichiometric amounts of H2L2, zinc
acetate and cesium acetate were combined, a mixture of two
compounds was generated. However, both components can
be synthesized separately by using the appropriate stoichi-
ometry (Scheme 3). The reaction of 1 equiv. of zinc acetate
and 2 equiv. of cesium acetate with 3 equiv. of H2L2 in a
mixture of acetonitrile and methanol (3:1) yielded one-di-
mensional meander polymer meso-(3c)n. In contrast, the re-
action of 4 equiv. of zinc acetate and 1 equiv. of cesium ace-
tate with 2 equiv. of H2L2 afforded {Csʚ[Zn2(L2)2OAc]}
cryptate 4a, which readily crystallized from a mixture of
acetonitrile and methanol (3:1) (Scheme 3, Figure 5). Anal-
ogously, supramolecular meso-(3d)n as well as metallacrypt-
ate 4b are accessible with rubidium (Schemes 2 and 3).
Metallacryptate 4a crystallizes in space group P21/c and has
idealized C2v molecule symmetry (Table 1).[6] Two hexaden-
tate bis(1,3-diketo) dianions (L2)2– together with an encap-
sulated cesium ion formally create a {2}-metallacoronate
that is folded by an acetate bridge. In the heteroleptic crypt-
ate, one acetate oxygen atom functions as a µ1-donor to one
zinc ion and the other as a µ2-donor to the other zinc ion,
but also to the cesium ion. In 4a, the cesium ion at one side
is coordinatively unsaturated and, therefore, two molecules
of 4a form a dimer due to cation–π interaction of neigh-
boring phenyl groups (Figure 5 bottom).[7]
Figure 5. Structure of heteroleptic cryptate 4a (top) and stereo
presentation (POVRAY) of the dimer of 4a (bottom). Zn grey, Cs
light grey.
of a 1:1 mixture of meso-(3a)n and meso-(3c)n in [D6]ace-
tone. A total of 22 signals was detected, which is twice the
number of signals for each individual compound. We thus
concluded that any Mg/Zn exchange process must be ex-
tremely slow on the NMR timescale. Unequivocally, we ob-
served intact cryptate monomers also in solution. For con-
venience, we present only the carbonyl 13C NMR signals for
cryptates meso-(3a)n and meso-(3c)n and their 1:1 mixture in
[D6]acetone (Figure 6).
Scheme 3. Synthesis of one-dimensional meandering polymers
meso-(3c,d)n and heteroleptic {2}-cryptates 4 (schematic presenta-
tion).
To prove the existence of the supramolecular cryptate
monomers of crystalline rac-(2)n and meso-(3)n also in solu-
tion, we carried out 1H and 13C NMR spectroscopic studies
of diamagnetic rac-(2)n and meso-(3a–d)n. It turned out that
Figure 6. 13C NMR signals for the carbonyl atoms of meso-(3a)n
and meso-(3c)n and their 1:1 mixture in [D6]acetone at ca. 25 °C.
The number of 13C NMR signals found for meso-(3a)n
the spectra of all five compounds were not very significant and meso-(3c)n observed in solution (11 each) suggests that
1
1
[5 H and 8 13C NMR signals for rac-(2)n and 7 H and 11 a homochiral (∆,∆/Λ,Λ) monomeric species exists as pro-
13C NMR signals for meso-(3a–d)n]. We were unable to de- posed from the X-ray data. However, the 13C NMR spec-
tect an AB pattern for the diastereotopic OCH2 protons, troscopic data would also match a heterochiral (∆,Λ) mono-
even by using variable temperature techniques.[8] The com- meric species. The monomeric homochiral species repre-
pounds meso-(3a)n and meso-(3c)n are identical except for sents the racemate, the heterochiral species is a monomeric
the metal ions magnesium or zinc. Exemplarily, their spec- meso compound. Therefore, provided that there are only
tra are discussed here in detail. They differ only slightly in minute chemical shift differences between the racemate and
their chemical shifts. To evaluate the intermolecular ex- meso compounds, there might be a mixture of both dia-
change processes, we also recorded a 13C NMR spectrum stereomers present. Normal 13C NMR spectroscopic pro-
4818
www.eurjic.org
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2007, 4815–4822

Synthesis and Structure of Self-Complementary {2}-Metallacryptates
H, OH), 6.98–6.95 (m, 2 H, Ar-H), 6.89–6.86 (m, 2 H, Ar-H), 5.98
(s, 2 H, CH), 4.65 (s, 4 H, CH2), 2.10 (s, 6 H, CH3) ppm. 13C NMR
(75.5 MHz): δ = 191.88 (2 C-OH), 190.50 (2 C=O), 148.04 (2 Ar-
C-O), 122.57 (2 Ar-C-H, m-C6H4), 114.69 (2 Ar-C-H, o-C6H4),
cessing yields only a single set of signals. However, we are
currently exploring whether these signals can be resolved
further. This requires 13C NMR spectroscopic data with
very high signal-to-noise ratios and resolution enhancement
techniques. We will report in forthcoming papers on these
results.
97.44 (2 CH), 70.24 (2 CH ), 24.47 (2 CH ) ppm. IR: ν = 2922,
˜
2
3
1609, 1589, 1509, 1225, 1124 cm–1. MS: m/z (%) = 307 (100) [M +
H]+, 222 (9) [M – COCH2COMe]+. C16H18O6 (306.32): calcd. C
62.74, H 5.92; found C 62.85, H 6.04.
H2L2: Acetophenone (11.67 mL). Yield: 10.3 g (48%), colorless
cotton-like crystals (methanol). M.p. 117 °C. 1H NMR
(300.1 MHz): δ = 15.87 (br. s, 2 H, OH), 7.78–7.76 (m, 4 H, Ar-H,
o-C6H5), 7.41–7.36 (m, 2 H, Ar-H, p-C6H5), 7.30–7.25 (m, 4 H, Ar-
H, m-C6H5), 6.93–6.86 (m, 4 H, Ar-H, C6H4), 6.66 (s, 2 H, CH),
4.72 (s, 4 H, CH2) ppm. 13C NMR (75.5 MHz): δ = 193.70 (2 C-
OH), 182.75 (2 C=O), 147.95 (2 Ar-C-O), 133.90 (2 Ar-C-C=O),
132.67 (2 Ar-C-H, p-C6H5), 128.62 (4 Ar-C-H, C6H5), 127.11 (4
Ar-C-H, C6H5), 122.54 (2 Ar-C-H, m-C6H4), 114.68 (2 Ar-C-H, o-
Conclusions
We presented the synthesis of the homochiral linear one-
dimensional polymers [{Csʚ[(∆,∆)-Mg2(L1)3]}Cs]n [∆-(2)n]
and [{Csʚ[(Λ,Λ)-Mg2(L1)3]}Cs]n [Λ-(2)n] and the one di-
mensional meander polymers meso-{[({M1ʚ[(∆,∆)-M2 -
2
(L2)3]}M1end)({M1ʚ[(Λ,Λ)-M22(L2)3]}M1side)][({M1ʚ
[(Λ,Λ)-M2 (L2)3]}M1end)({M1ʚ[(∆,∆)-M2 (L2)3]}M1side)]}n
2
2
[meso-(3)n] (M1 = Cs+, Rb+; M2 = Mg2+, Co2+, Zn2+). The
structures of complexes 1–4 were solved by the combination
C H ), 93.44 (2 CH), 70.73 (2 CH ) ppm. IR: ν = 3050, 2890, 2830,
˜
6
4
2
1610, 1575, 1509, 1262, 1227, 1127 cm–1. MS: m/z (%) = 431 (100)
[M]+. C26H22O6 (430.46): calcd. C 72.55, H 5.15; found C 72.19, H
5.13.
1
of mass spectroscopy, single-crystal X-ray analyses and H
and 13C NMR spectroscopy. Most importantly, the 13C
NMR spectrum of a mixture of meso-(3a,c) unequivocally
proved the existence of the intact cryptates {Csʚ[Mg2-
(L2)3]}– of meso-(3a)n and {Csʚ[Zn2(L2)3]}– of meso-(3c)n
in solution.
∆/Λ-(2)n: A solution of cesium acetate (25 mg, 131 µmol) in MeOH
(1 mL) was added to a solution of ligand H2L1 (40 mg, 131 µmol)
in MeOH (3 mL). The mixture was heated to boiling. Then a solu-
tion of Mg(OAc)2·4H2O (19 mg, 87 µmol) in MeOH (1 mL) was
prepared at boiling heat and added dropwise. After cooling and
filtration of the resulting mixture, the crude product was obtained
in the form of microcrystals by vapour diffusion of diethyl ether
into the filtrate. Recrystallisation from acetonitrile by vapour dif-
fusion of diethyl ether gave colourless crystals of ∆/Λ-(2·3CH3-
CN)n, suitable for X-ray structure determination. Yield: 25 mg
(47%) of ∆/Λ-(2)n after drying for 8 h under reduced pressure
(10–3 mbar). M.p. Ͼ260 °C (decomp). 1H NMR (300.1 MHz,
XXXX): δ = 6.76 (br. s, 6 H, Ar-H), 6.46 (br. s, 6 H, Ar-H), 4.75
(br. s, 6 H, CH), 4.03 (br. s, 12 H, CH2), 1.78 (br. s, 18 H, CH3)
ppm. 13C NMR (100.5 MHz, XXXX): δ = 191.66 (6 C=O), 183.23
(6 C=O), 146.42 (6 Ar-C-O), 120.67 (6 Ar-C-H), 111.67 (6 Ar-C-
Experimental Section
General Techniques: All solvents used were purified according to
standard procedures. All reagents employed were commercially
available, high-grade purity materials and used as supplied (Fluka,
Aldrich and Acros). Melting points were determined with a
WAGNER-MUNZ apparatus and are uncorrected. IR spectra
were recorded as powder films with a ASI React IR-1000 spectrom-
eter. NMR spectra were obtained from dilute solutions in CDCl3,
unless stated otherwise, and recorded with a JEOL EX400 or a
BRUKER Avance 300 spectrometer. The residual solvent signals
were used as internal standards: CDCl3 (1H 7.27 ppm, 13C
77.0 ppm); [D6]acetone (1H 2.05 ppm; 13C 29.85 ppm).[9] The reso-
nance multiplicity is indicated as s (singlet), d (doublet) and m
(multiplet). MS (FAB) spectra were recorded with a Micromass
ZAB-Spec (Cs+) spectrometer with m-NBA as matrix. Elemental
analyses were performed with a Carlo Erba EA1110 CHN instru-
ment and with a HERAEUS CHN-Mikroautomat.
H), 95.11 (6 CH), 68.24 (6 CH ), 28.21 (6 CH ) ppm. IR: ν = 3065,
˜
2
3
2910, 1613, 1521, 1235, 1127, 1054 cm–1. MS: m/z (%) = 1359 (15)
[CsʚMg2L3 + 2Cs]+, 1227 (22) [CsʚMg2L3 + Cs]+, 789 (100)
[Mg2L2 + Cs]+, 691 (16) [Mg2L2 + Cs – CH2COCHCOCH3]+.
C48H48Cs2Mg2O18 (1227.40): calcd. C 46.97, H 3.95; found C
46.47, H 4.13.
General Procedure for meso-(3a,b,e)n: A solution of cesium or ru-
bidium acetate (77 µmol) in MeOH (1 mL) was added to a solution
of ligand H2L2 (50 mg, 116 µmol) in acetonitrile (3 mL). The mix-
ture was heated to boiling. Then a solution of M2(OAc)2·xH2O
(77 µmol) in MeOH (1 mL) was prepared at boiling heat and added
dropwise. After cooling and filtration of the resulting mixture, the
product was obtained in the form of crystals by vapour diffusion
of diethyl ether into the filtrate.
General Procedure for H2L1,2 [2,10]
To a suspension of sodium amide
:
(7.8 g, 200 mmol) in THF (200 mL) was added a solution of the
corresponding methyl ketone (100 mmol) in THF (20 mL) by a
dropping funnel. After 15 min, a solution of ester 1,2-bis(methyl-
acetoxy)benzene[11] (12.71 g, 50 mmol) in THF (20 mL) was added.
After heating at reflux for 4 h, cooling to room temp. and the ad-
dition of water (5 mL), the mixture was concentrated under re-
duced pressure. The residue was taken up in water (100 mL) and
acidified with concentrated HCl (30 mL). Extraction of the aque-
ous phase with chloroform (3ϫ100 mL), drying (over sodium sul-
fate) and evaporation of the combined organic phases yielded the
crude reaction product, which was further purified by recrystalli-
zation. In solution, the ligands H2L1,2 are present as a tautomeric
mixture of the diketo, monoenol and bisenol species. Below, only
signals of the dominating bisenol form are listed.
meso-(3a)n: CsOAc (15 mg) and Mg(OAc)2·4H2O (17 mg). Yield:
38 mg (62%), colorless crystals after drying for 8 h under reduced
pressure (10–3 mbar). M.p. Ͼ220 °C (decomp). 1H NMR
(300.1 MHz, [D6]acetone): δ = 7.88–7.85 (m, 12 H, Ar-H, o-C6H5),
7.41–7.31 (m, 18 H, Ar-H, m- and p-C6H5), 6.61–6.58 (m, 6 H, Ar-
H, C6H4), 6.33–6.30 (m, 6 H, Ar-H, C6H4), 5.63 (br. s, 6 H, CH),
4.33 (br. s, 12 H, CH2) ppm. 13C NMR (75.5 MHz, [D6]acetone):
δ = 186.32 (6 C=O), 184.80 (6 C=O), 147.65 (6 Ar-C-O), 142.54 (6
Ar-C-C=O), 130.71 (6 Ar-C-H, p-C6H5), 128.64 (12 Ar-C-H,
C6H5), 128.16 (12 Ar-C-H, C6H5), 121.41 (6 Ar-C-H, m-C6H4),
112.57 (6 Ar-C-H, o-C6H4), 92.30 (6 CH), 69.60 (6 CH2) ppm. IR:
H2L1: Acetone (7.34 mL). Yield: 5.5 g (36%), bright-beige crystals
(methanol). M.p. 92 °C. H NMR (300.1 MHz): δ = 15.26 (br. s, 2
1
Eur. J. Inorg. Chem. 2007, 4815–4822
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4819

R. W. Saalfrank et al.
FULL PAPER
ν = 3065, 2918, 1610, 1575, 1502, 1247, 1127, 1042 cm–1. MS: m/z
C=O), 147.33 (6 Ar-C-O), 141.95 (6 Ar-C-C=O), 130.21 (6 Ar-C-
H, p-C6H5), 128.11 (12 Ar-C-H, C6H5), 127.60 (12 Ar-C-H, C6H5),
˜
(%) = 1732 (83) [CsʚMg2L3 + 2Cs]+, 1601 (23) [CsʚMg2L3
+
Cs]+, 1038 (100) [Mg2L2 + Cs]+, 877 (32) [Mg2L2 + Cs – 120.87 (6 Ar-C-H, m-C6H4), 112.15 (6 Ar-C-H, o-C6H4), 92.02 (6
CH2COCHCOC6H5]+, 718 (21) [Mg2L2 + Cs – 2CH2COCH-
COC6H5]+. C78H60O18Cs2Mg2 (1599.82): calcd. C 58.56, H 3.79;
found C 57.71, H 3.93.
CH), 69.22 (6 CH ) ppm. IR: ν = 3065, 2918, 1598, 1571, 1513,
˜
2
1247, 1127, 1038 cm–1. MS: m/z (%) = 1671 (32) [RbʚZn2L3
+
2Rb]+, 1587 (17) [RbʚZn2L3 + Rb]+, 1073 (100) [Zn2L2 + Rb]+,
913 (27) [Zn2L2 + Rb – CH2COCHCOC6H5]+. C78H60O18Rb2Zn2
(1587.10): calcd. C 59.02, H 3.82; found C 58.76, H 3.97.
meso-(3b)n: RbOAc (11 mg) and Mg(OAc)2·4H2O (17 mg), color-
less crystals of meso-(3b·2CH3CN)n suitable for X-ray structure de-
termination. Yield: 21 mg (36%) of meso-(3b)n after drying for 8 h
under reduced pressure (10–3 mbar). M.p. Ͼ190 °C (decomp). 1H
NMR (300.1 MHz, [D6]acetone): δ = 7.88–7.85 (br. s, 12 H, Ar-H,
o-C6H5), 7.40–7.30 (m, 18 H, Ar-H, m- and p-C6H5), 6.57 (br. s, 6
H, Ar-H, C6H4), 6.26 (br. s, 6 H, Ar-H, C6H4), 5.60 (br. s, 6 H,
CH), 4.28 (br. s, 12 H, CH2) ppm. 13C NMR (75.5 MHz, [D6]ace-
tone): δ = 185.79 (6 C=O), 184.40 (6 C=O), 147.34 (6 Ar-C-O),
141.86 (6 Ar-C-C=O), 130.15 (6 Ar-C-H, p-C6H5), 128.03 (12 Ar-
C-H, C6H5), 127.63 (12 Ar-C-H, C6H5), 120.85 (6 Ar-C-H, m-
C6H4), 112.07 (6 Ar-C-H, o-C6H4), 92.12 (6 CH), 69.24 (6 CH2)
General Procedure for 4a,b: A solution of cesium or rubidium ace-
tate (29 µmol) in MeOH (1 mL) was added to a solution of ligand
H2L2 (25 mg, 58 µmol) in acetonitrile (3 mL). The mixture was
heated to boiling. Then a solution of Zn(OAc)2·2H2O (25 mg,
116 µmol) in MeOH (1 mL) was prepared at boiling heat and
added dropwise. After cooling and filtration of the resulting mix-
ture, the product precipitated from the filtrate during 12 h in the
form of crystals.
4a: CsOAc (6 mg). Colorless crystals of 4a·3CH3CN suitable for
X-ray structure determination by vapour diffusion of diethyl ether
into a mother liquor of 4a in acetonitrile. Yield: 59 mg (86%) of
4a after drying for 8 h under reduced pressure (10–3 mbar). M.p.
Ͼ210 °C (decomp). 1H NMR (300.1 MHz): δ = 7.93–7.91 (m, 8 H,
Ar-H, o-C6H5), 7.42–7.31 (m, 12 H, Ar-H, m- and p-C6H5), 6.95
ppm. IR: ν = 3065, 2922, 1606, 1575, 1502, 1247, 1127, 1038 cm–1.
˜
MS: m/z (%) = 1590 (27) [RbʚMg2L3 + 2 Rb]+, 1505 (28)
[RbʚMg2L3 + Rb]+, 991 (100) [Mg2L2 + Rb]+, 831 (25) [Mg2L2 +
Rb – CH2COCHCOC6H5]+. C78H60Mg2O18Rb2 (1504.94): calcd.
C 62.26, H 4.02; found C 63.00, H 3.89.
2
(ps-s, 8 H, Ar-H, C6H4), 5.97 (s, 4 H, CH), 4.71 (d, J = 12.0 Hz,
4 H, CH2), 4.36 (d, 2J = 12.0 Hz, 4 H, CH2), 2.20 (s, 3 H, CH3)
ppm. 13C NMR (75.5 MHz): δ = 188.30 (4 C=O), 186.51 (4 C=O),
180.38 (H3C-CO2), 148.46 (4 Ar-C-O), 139.72 (4 Ar-C-C=O),
131.05 (2 Ar-C-H, p-C6H5), 128.03 (4 Ar-C-H, C6H5), 127.57 (8
Ar-C-H, C6H5), 122.82 (4 Ar-C-H, m-C6H4), 115.95 (4 Ar-C-H, o-
meso-(3e)n: CsOAc (15 mg) and Co(OAc)2·4H2O (19 mg), red crys-
tals of meso-(3e·10CH3CN·18CH3OH)n suitable for X-ray structure
determination. Yield: 45 mg (70%) of meso-(3e)n after drying for
8 h under reduced pressure (10–3 mbar). M.p. Ͼ220 °C (decomp).
IR: ν = 3061, 2918, 1598, 1571, 1502, 1243, 1127, 1038 cm–1. MS:
˜
m/z (%) = 1799 (42) [CsʚCo2L3 + 2Cs]+, 1669 (74) [CsʚCo2L3 +
Cs]+, 1536 (31) [CsʚCo2L3]+, 1107 (100) [Co2L2 + Cs]+, 947 (27)
[Co2L2 + Cs – CH2COCHCOC6H5]+. C78H60O18Co2Cs2 (1669.06):
calcd. C 56.13, H 3.63; found C 56.68, H 3.81.
C H ), 93.79 (4 CH), 73.90 (4 CH ), 24.56 (CH -CO ) ppm. IR: ν
˜
6
4
2
3
2
= 3065, 2903, 2849, 1598, 1567, 1521, 1254, 1119, 1034 cm–1. MS:
m/z (%)
= –
1121 (84) [CsʚZn2L2]+, 959 (11) [CsʚZn2L2
CH2COCHCOC6H5]+, 625 (17) [ZnL + Cs]+. C54H43O14CsZn2
(1179.66): calcd. C 54.98, H 3.68; found C 54.81, H 3.69.
General Procedure for meso-(3c,d)n: A solution of cesium or rubid-
ium acetate (116 µmol) in MeOH (1 mL) was added to a solution
of ligand H2L2 (75 mg, 174 µmol) in acetonitrile (5 mL). The mix-
ture was heated to boiling. Then a solution of Zn(OAc)2·2H2O
(13 mg, 58 µmol) in MeOH (1 mL) was prepared at boiling heat
and added dropwise. After cooling and filtration of the resulting
mixture, the product precipitated from the filtrate during 12 h in
the form of crystals.
4b: RbOAc (4 mg). Colorless crystals of 4b·2CH3CN·CH3OH suit-
able for X-ray structure determination by vapour diffusion of di-
ethyl ether into a mother liquor of 4b in acetonitrile. Yield: 47 mg
(72%) of 4b after drying for 8 h under reduced pressure
1
(10–3 mbar). M.p. Ͼ210 °C (decomp). H NMR (300.1 MHz): δ =
7.94–7.91 (m, 8 H, Ar-H, o-C6H5), 7.43–7.32 (m, 12 H, Ar-H, m-
and p-C6H5), 6.99 (ps-s, 8 H, Ar-H, C6H4), 5.94 (s, 4 H, CH), 4.71
(d, 2J = 12.6 Hz, 4 H, CH2), 4.37 (d, 2J = 12.6 Hz, 4 H, CH2), 2.25
(s, 3 H, CH3) ppm. 13C NMR (75.5 MHz): δ = 188.10 (4 C=O),
186.79 (4 C=O), 180.67 (H3C-CO2), 148.76 (4 Ar-C-O), 139.69 (4
Ar-C-C=O), 131.05 (2 Ar-C-H, p-C6H5), 128.04 (4 Ar-C-H, C6H5),
127.53 (8 Ar-C-H, C6H5), 123.07 (4 Ar-C-H, m-C6H4), 116.71 (4
Ar-C-H, o-C6H4), 93.31 (4 CH), 73.78 (4 CH2), 24.74 (CH3-CO2)
meso-(3c)n: CsOAc (22 mg). Yield: 32 mg (66%), colorless crystals
of meso-(3c)n after drying for 8 h under reduced pressure
(10–3 mbar). M.p. Ͼ190 °C (decomp). 1H NMR (300.1 MHz, [D6]-
acetone): δ = 7.85–7.83 (m, 12 H, Ar-H, o-C6H5), 7.31–7.41 (m, 18
H, Ar-H, m- and p-C6H5), 6.57 (br. s, 6 H, Ar-H, C6H4), 6.35 (br.
s, 6 H, Ar-H, C6H4), 5.56 (br. s, 6 H, CH), 4.27 (br. s, 12 H, CH2)
ppm. 13C NMR (100.5 MHz, [D6]acetone): δ = 187.14 (6 C=O),
185.68 (6 C=O), 147.65 (6 Ar-C-O), 142.61 (6 Ar-C-C=O), 130.74
(6 Ar-C-H, p-C6H5), 128.68 (12 Ar-C-H, C6H5), 128.10 (12 Ar-C-
H, C6H5), 121.43 (6 Ar-C-H, m-C6H4), 112.57 (6 Ar-C-H, o-C6H4),
ppm. IR: ν = 3065, 2903, 2845, 1594, 1563, 1521, 1254, 1119,
˜
1034 cm–1. MS: m/z (%) = 1073 (100) [RbʚZn2L2]+, 913 (23)
[RbʚZn2L2 – CH2COCHCOC6H5]+, 579 (39) [ZnL + Rb]+.
C54H43O14RbZn2 (1132.22): calcd. C 57.28, H 3.84; found C 56.82,
H 3.91.
92.11 (6 CH), 69.58 (6 CH ) ppm. IR: ν = 3065, 2918, 1598, 1571,
˜
2
1502, 1243, 1127, 1038 cm–1. MS: m/z (%) = 1813 (33) [CsʚZn2L3
+ 2Cs]+, 1683 (11) [CsʚZn2L3 + Cs]+, 1121 (100) [Zn2L2 + Cs]+,
961 (16) [Zn2L2 + Cs – CH2COCHCOC6H5]+. C78H60O18Cs2Zn2
(1681.98): calcd. C 55.70, H 3.60; found C 55.56, H 3.69.
Single Crystal X-ray Structure Analyses: Details of crystal data,
data collection and refinement are given in Table 1. X-ray data for
∆/Λ-(2)n, meso-(3e)n, 4a and 4b were collected with a Nonius
Kappa CCD area detector by using Mo-Kα radiation (λ =
0.71073 Å). The structures were solved by direct methods with
SHELXS-97[12] and refined with full-matrix least-squares against
F2 using the SHELXL-97 program system.[13] All non-hydrogen
atoms were refined anisotropically. The positions of the hydrogen
meso-(3d)n: RbOAc (17 mg). Yield: 14 mg (45%), colorless crystals
of meso-(3d)n after drying for 8 h under reduced pressure
(10–3 mbar). M.p. Ͼ180 °C (decomp). 1H NMR (300.1 MHz, [D6]-
acetone): δ = 7.81 (br. s, 12 H, Ar-H, o-C6H5), 7.38–7.32 (m, 18 H,
Ar-H, m- and p-C6H5), 6.56 (br. s, 6 H, Ar-H, C6H4), 6.30 (br. s, 6 atoms were fixed in ideal positions (riding model) and were in-
H, Ar-H, C6H4), 5.52 (br. s, 6 H, CH), 4.24 (br. s, 12 H, CH2) ppm. cluded without refinement and with fixed isotropic U. Data for
13C NMR (75.5 MHz, [D6]acetone): δ = 186.70 (6 C=O), 185.30 (6 meso-(3b)n were collected with a Bruker-Nonius KappaCCD dif-
4820
www.eurjic.org
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2007, 4815–4822

Synthesis and Structure of Self-Complementary {2}-Metallacryptates
Table 1. Crystal and structure refinement data for complexes ∆/Λ-(2)n, meso-(3b)n, meso-(3e)n, 4a and 4b.
∆/Λ-(2)n
meso-(3b)n
meso-(3e)n
Empirical formula
Mr [gmol–1
C48H48Cs2Mg2O18·3CH3CN
1350.47
C156H120Mg4O36Rb4·2CH3CN
3091.84
C312H240Co8Cs8O72·10CH3CN·18CH3OH
7663.06
]
Crystal size [mm]
0.35ϫ0.20ϫ0.15
triclinic
P1
0.18ϫ0.16ϫ0.13
monoclinic
P21/n
25.643(2)
21.655(2)
0.25ϫ0.20ϫ0.20
monoclinic
P21/n
25.9749(3)
21.6357(2)
30.2700(3)
Crystal system
Space group
a [Å]
b [Å]
c [Å]
¯
11.9122(3)
16.1944(2)
17.7467(3)
114.852(1)
96.960(1)
95.055(1)
3046.65(10)
2
1.472
173(2)
1.286
1360
29.756(2)
α [°]
β [°]
90.502(6)
90.077(3)
γ [°]
V [Å3]
Z
16523(2)
4
1.243
100(2)
1.263
17011.3(3)
2
1.496
173(2)
1.308
ρcalcd. [Mgm–3
T [K]
]
Absorption coeff. [mm–1
F(000)
]
6336
7776
θ range [°]
Index ranges
1.74 to 27.50
–15ՅhՅ15
–21ՅkՅ21
–23ՅlՅ23
26391
3.38 to 27.00
–32ՅhՅ32
–27ՅkՅ27
–37ՅlՅ37
166961
1.03 to 26.01
–31ՅhՅ32
–24ՅkՅ26
–37ՅlՅ37
88290
Reflections collected
Independent reflections
13968
35804
31901
Refl. observed [IՆ2σ(I)]
Absorption correction
Refinement method
Max./Min. transm.
10176
22949
19074
Scalepack
full-matrix least-squares on F2
0.8305/0.6617
0.0226
SADABS
full-matrix least-squares on F2
0.850/0.783
0.0699
Scalepack
full-matrix least-squares on F2
0.7799/0.7357
0.0705
[Rint
]
Data/parameters
13968/732
0.983
0.0430
0.1470
2.019/–1.330
35804/1922
1.067
0.0537
0.1425
2.913/–1.162
31901/2093
0.929
0.0484
0.1520
1.263/–1.252
Goodness-of-fit on F2
Final R1 [IՆ2σ(I)]
wR2 (all data)
Largest residuals [eÅ–3
]
4a
4b
Empirical formula
C54H43CsO14Zn2·3CH3CN
1302.70
C54H43O14RbZn2·2CH3CN·CH3OH
1246.24
Mr [gmol–1
]
Crystal size [mm]
0.30ϫ0.30ϫ0.30
monoclinic
P21/c
19.0036(3)
14.4150(2)
0.20ϫ0.20ϫ0.20
monoclinic
P21/c
18.7116(4)
14.6150(3)
20.3408(4)
Crystal system
Space group
a [Å]
b [Å]
c [Å]
20.5309(3)
α [°]
β [°]
103.511(1)
103.419(1)
γ [°]
V [Å3]
Z
5468.52(14)
4
1.582
173(2)
1.605
5410.73(19)
4
1.530
173(2)
1.852
ρcalcd. [Mgm–3
T [K]
]
Absorption coeff. [mm–1
F(000)
]
2640
2552
θ range [°]
Index ranges
1.10 to 27.49
–24ՅhՅ24
–18ՅkՅ17
–26ՅlՅ26
23739
2.06 to 27.48
–24ՅhՅ24
–18ՅkՅ17
–26ՅlՅ26
22634
Reflections collected
Independent reflections
12546
12355
Refl. observed [IՆ2σ(I)]
Absorption correction
Refinement method
Max./Min. transm.
9906
7781
Scalepack
full-matrix least-squares on F2
0.6446/0.6446
0.0247
Scalepack
full-matrix least-squares on F2
0.7083/0.7083
0.0417
[Rint
]
Data/parameters
12546/721
1.022
0.0328
0.1049
0.745/–0.841
12355/712
1.000
0.0479
0.1321
1.149/–0.583
Goodness-of-fit on F2
Final R1 [IՆ2σ(I)]
wR2 (all data)
Largest residuals [eÅ–3
]
Eur. J. Inorg. Chem. 2007, 4815–4822
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjic.org
4821

R. W. Saalfrank et al.
FULL PAPER
J. Rebek Jr, Angew. Chem. 2002, 114, 1556–1578; Angew. Chem.
Int. Ed. 2002, 41, 1488–1508; g) B. J. Holliday, C. A. Mirkin,
Angew. Chem. 2001, 113, 2076–2098; Angew. Chem. Int. Ed.
2001, 40, 2022–2043; h) S. R. Seidel, P. J. Stang, Acc. Chem.
Res. 2002, 35, 972–983; i) L. R. MacGillivray, J. L. Atwood,
Angew. Chem. 1999, 111, 1080–1096; Angew. Chem. Int. Ed.
1999, 38, 1018–1033; j) E. Barea, J. A. R. Navarro, J. M. Salas,
M. Quirós, M. Willermann, B. Lippert, Chem. Eur. J. 2003, 9,
4414–4421; k) R. E. P. Winpenny in Perspectives in Supramolec-
ular Chemistry (Ed.: J. P. Sauvage), Wiley-VCH, Weinheim,
1999, vol. 5, pp. 193–223; l) A. D. Cutland, R. G. Malkani,
J. W. K a m p f, V. L . Pe c o r a ro, Angew. Chem. 2000, 112, 2801–
2803; Angew. Chem. Int. Ed. 2000, 39, 2689–2691; m) H. Oshio,
N. Hoshino, T. Ito, M. Nakano, F. Renz, P. Gütlich, Angew.
Chem. 2003, 115, 233–235; Angew. Chem. Int. Ed. 2003, 42,
223–225; n) M. Albrecht, Chem. Rev. 2001, 101, 3457–3497;
o) S. P. Watton, P. Fuhrmann, L. E. Pence, S. J. Lippard, A.
Caneschi, A. Cornia, G. L. Abbati, Angew. Chem. 1997, 109,
2917–2919; Angew. Chem. Int. Ed. Engl. 1997, 36, 2774–2776.
[6] CCDC-637293 [for meso-(3b)n], -641321 (for 4b), -641322 [for
meso-(3e)n], -641323 [for ∆/Λ-(2)n] and -641652 (for 4a) contain
the supplementary crystallographic data for this paper. These
data can be obtained free of charge from the Cambridge Crys-
tallographic data centre via www.ccdc.cam.ac.uk/data_request/
cif. For further details of crystal data, data collection and re-
finement, see Table 1 and the Experimental Section.
fractometer by using Mo-Kα radiation (λ = 0.71073 Å), and a
graphite monochromator. The structure was solved by direct meth-
ods; full-matrix least-squares refinements were carried out on F2
using SHELXTL NT 6.12.[14] A semiempirical absorption correc-
tion based on multiple scans (SADABS)[15] was performed. All
non-hydrogen atoms were refined anisotropically. The H atoms
were geometrically positioned with isotropic displacement param-
eters being either 1.2 U(eq) or 1.5 U(eq) of the proceeding C atom.
Disorder: Two of the aromatic rings (C99–C104 and C125–C130)
are disordered with 42.6(5) and 57.4(5)% and 47.8(4) and
52.2(4)%, respectively. In the crystal structure two huge cavities are
present that are occupied by different disordered solvent molecules.
Attempts to solve this disorder did not lead to reasonable results
and therefore the SQUEEZE algorithm was employed to treat the
rest electron density in this part of the structure.[16]
Acknowledgments
This work was supported by the Deutsche Forschungsgemeinschaft
Sa 276/27-1-2, SFB 583, GK 312, SPP 1137 “Molecular Magnet-
ism” (Sa 276/26-1-3), the Bayerisches Langzeitprogrammm Neue
Werkstoffe, and the Fonds der Chemischen Industrie. N. M. thanks
the Freistaat Bayern for a scholarship. The generous allocation of
premises by Prof. Dr. K. Meyer at the Institut für Anorganische
Chemie (University of Erlangen-Nürnberg) is gratefully acknowl-
edged.
[7] a) A. Åhman, M. Nissinen, Chem. Commun. 2006, 1209–1211;
b) A. B. Rozhenko, W. W. Schoeller, M. C. Letzel, B. Decker,
C. Agena, J. Mattay, J. Mol. Struct. (Theochem.) 2005, 732, 7–
20; c) M. T. Gamer, P. W. Roesky, Inorg. Chem. 2005, 44, 5963–
5965.
[8] Geminal diastereotopic nuclei are inherently nonisochronous.
However, chemical shift differences and/or coupling constants
may be vanishingly small.
[1] R. W. Saalfrank, A. Scheurer, R. Prakash, F. W. Heinemann,
T. Nakajima, F. Hampel, R. Leppin, B. Pilawa, H. Rupp, P.
Müller, Inorg. Chem. 2007, 46, 1586–1592.
[2] R. W. Saalfrank, H. Maid, N. Mooren, F. Hampel, Angew.
Chem. 2002, 114, 323–326; Angew. Chem. Int. Ed. 2002, 41,
304–307.
[3] R. W. Saalfrank, A. Scheurer, R. Puchta, F. Hampel, H. Maid,
F. W. Heinemann, Angew. Chem. 2007, 119, 269–272; Angew.
Chem. Int. Ed. 2007, 46, 265–268.
[9] H. E. Gottlieb, V. Kotlyar, A. Nudelman, J. Org. Chem. 1997,
62, 7512–7515.
[10]
[11]
D. E. Fenton, J. R. Tate, U. Casellato, S. Tamburini, P. A. Vi-
gato, M. Vidali, Inorg. Chim. Acta 1984, 83, 23–31.
D. T. Gryko, P. Piatek, J. Jurczak, Tetrahedron 1997, 53, 7957–
7966.
˛
[4] R. W. Saalfrank, C. Schmidt, H. Maid, F. Hampel, W. Bauer,
A. Scheurer, Angew. Chem. 2006, 118, 322–325; Angew. Chem.
Int. Ed. 2006, 45, 315–318.
[5] a) R. W. Saalfrank, B. Demleitner in Perspectives in Supramo-
lecular Chemistry (Ed.: J. P. Sauvage), Wiley-VCH, Weinheim,
1999, vol. 5, pp. 1–51; b) E. Uller, B. Demleitner, I. Bernt,
[12] G. M. Sheldrick, C. Krüger, P. Goddard, Crystallographic
Computing 3, Oxford University Press, Oxford, 1985, p. 175.
[13] G. M. Sheldrick, SHELXL-97, Program for Crystal Structure
Refinement, University Göttingen, 1997.
[14] SHELXTL NT 6.12, Bruker AXS Inc., Madison, WI, USA,
2002.
R. W. Saalfrank in Structure and Bonding (Ed.: M. Fujita), [15] SADABS 2.06, Bruker AXS Inc., Madison, WI, USA, 2002.
Springer, Berlin, 2000, vol. 96, pp. 149–175; c) D. L. Caulder,
K. N. Raymond, Acc. Chem. Res. 1999, 32, 975–982; d) M.
Fujita, Chem. Soc. Rev. 1998, 27, 417–425; e) C. J. Jones, Chem.
Soc. Rev. 1998, 27, 289–299; f) F. Hof, S. L. Craig, C. Nuckolls,
[16] P. v. d. Sluis, A. L. Spek, Acta Crystallogr., Sect. A 1990, 46,
194–201.
Received: June 4, 2007
Published Online: August 28, 2007
4822
www.eurjic.org
© 2007 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
Eur. J. Inorg. Chem. 2007, 4815–4822