A silver bite: Crystalline heterometallic architectures based on Ag-π interactions with a bis-dipyrrin zinc helicate

Article abstract of DOI:10.1002/chem.201304319

An unprecedented mode of assembly of helical motives and Ag^Ia ions in the crystalline state is described. The combination of a Zn^II helicate based on a 2,2′-bisdpm bearing peripheral benzonitrile moieties with AgX salts, leads to the formation of a tetranuclear core containing Ag-π interactions. Depending on the coordinating ability of the X^- anion and the solvents used, the tetranuclear complex self-assembles into coordination polymers of varying dimensionality. From the sequence of coordination events (Ag-π or Ag-peripheral site), one may envisage two possible construction scenarios. However, the Ag-π as primary event seems reasonable owing to the rather weak binding propensity of the nitrile group and the chelating nature of the π-clefts. The π-clefts, formed by a 2,2′-bisdipyrrin benzonitrile appended ligand assembled into a double stranded helicate by two Zn^IIa ions, have been employed for the complexation of two Ag ^Ia ions by Ag-π interactions. Depending on the anion and solvent used, the tetranuclear Ag₂Zn₂ double stranded helical metallatecton leads to a variety of heterometallic species ranging from discrete to infinite periodic architectures in the crystalline state (see figure). Copyright

Full text of DOI:10.1002/chem.201304319

DOI: 10.1002/chem.201304319
Communication
&
Coordination Polymers
A Silver Bite: Crystalline Heterometallic Architectures Based on
Ag–p Interactions with a Bis-Dipyrrin Zinc Helicate
Hervꢀ Ruffin, Stꢀphane A. Baudron,* Domingo Salazar-Mendoza, and Mir Wais Hosseini*[a]
Abstract: An unprecedented mode of assembly of helical
motives and AgI ions in the crystalline state is described.
The combination of a ZnII helicate based on a 2,2’-bisdpm
bearing peripheral benzonitrile moieties with AgX salts,
leads to the formation of a tetranuclear core containing
Ag–p interactions. Depending on the coordinating ability
of the Xꢀ anion and the solvents used, the tetranuclear
complex self-assembles into coordination polymers of
varying dimensionality. From the sequence of coordina-
tion events (Ag–p or Ag–peripheral site), one may envis-
age two possible construction scenarios. However, the
Scheme 1. Representations of dipyrrin, 2,2’-bisdipyrrin, a ZnII double helicate,
Ag–p as primary event seems reasonable owing to the
and positional isomers of the heterometallic tetranuclear Ag2Zn2 species.
rather weak binding propensity of the nitrile group and
the chelating nature of the p-clefts.
ing to the peripheral coordinating pole.[5] Whereas this interac-
tion has been documented with aromatic compounds,[6] its ob-
Over the past decade, the sequential approach for the con-
struction of heterometallic coordination polymers (CPs) and
metal–organic frameworks (MOFs), relying on the use of li-
gands bearing differentiated coordination poles, has demon-
strated its efficiency.[1] In this strategy, coordination of a first
metal center leads to the formation of a discrete complex
bearing peripheral binding sites which may be regarded as
servation in the solid state with pyrrolic systems remains rather
rare.[5,7] In solution, it has been investigated with tetrapyrrolic
derivatives such as 3,3’-bisdipyrrin helicates and Ce(IV) double-
decker porphyrins.[8,9] In the latter type of compounds, two
pyrrolic rings of facing macrocycles form p-clefts interacting
with AgI ions, as determined by NMR, Raman, and UV/Vis spec-
troscopies.[9] Based on our previous investigations on Ag–p in-
teractions in the crystalline phase,[5] it appeared interesting to
exploit this type of interaction as a construction strategy for
the generation of extended heterometallic architectures. Such
an approach requires the design of metallatectons incorporat-
ing both p-clefts and peripheral coordinating sites. Interesting-
ly, bis- and oligo-pyrrolic ligands[10] have been shown to form
helicates with ZnII ions.[11] In particular, the 2,2’-bisdipyrrin ZnII
double helicate (Scheme 1) displays four p-clefts formed by
pyrrolic rings of two different strands. Owing to the proper dis-
position and distances between the p-bonds, such a helicate
should behave as a silver binder through Ag–p interaction
leading thus to three tetranuclear Ag2Zn2 heterometallic posi-
tional isomers (Scheme 1). Upon introducing two peripheral
coordinating sites at both positions 5 on the 2,2’-bisdipyrrin
backbone, the binuclear silver ZnII helicate should behave as
a self-complementary metallatecton displaying simultaneously
four coordinating sites and two secondary metal centers offer-
ing free coordination sites. The latter, in principle, should self-
assemble into CPs upon coordination of the peripheral binding
units to the AgI centers. Although helicate type complexes
have been investigated with a variety of organic ligands and
metals,[12] only very few have been employed as metallatectons
a
metallatecton.[1,2] The latter leads in the presence of
a second metal cation to a self-assembled heterometallic peri-
odic architecture. Although, following this strategy, a variety of
ligands has been employed, the bis-pyrrolic derivatives of the
dipyrrin type (dpm) appeared as particularly appealing.[3]
Indeed, not only the dpm moiety forms a monoanionic chelate
under mild basic conditions, but its straightforward functionali-
zation at position 5 by an additional peripheral coordinating
site leads to a family of differentiated ligands (Scheme 1).
Using this type of multipole ligand, several dpm-based hetero-
metallic CPs have been described, in particular with AgI as the
secondary metal center.[4,5] In some of these architectures, the
AgI ion is found to form Ag–p interactions[6] with C=C bonds
of the dpm chelate, in addition to the expected classical bind-
[a] H. Ruffin, Dr. S. A. Baudron, Dr. D. Salazar-Mendoza, Prof. M. W. Hosseini
Laboratoire de Tectonique Molꢀculaire, UMR UdS-CNRS 7140
icFRC, Institut Le Bel, Universitꢀ de Strasbourg
4 rue Blaise Pascal, CS 90032, 67081 Strasbourg cedex (France)
Fax: (+33)3-68-85-13-25
E-mail: sbaudron@unistra.fr
hosseini@unistra.fr
Supporting information for this article is available on the WWW under
http://dx.doi.org/10.1002/chem.201304319.
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respectively. Reaction of the latter with Zn(OAc)2 af-
forded quantitatively the helicate 5.
The crystal structures of all five compounds 1–5
determined by X-Ray diffraction (Table S1 in the Sup-
porting Information) are given in Figure 1. For 1, the
two pyrrolic rings are almost coplanar, owing to the
presence of an intramolecular hydrogen bond (NꢀHꢀ
N=2.716(3) ꢂ, 124.68) as observed for other dipyr-
rins.[17] The NiII ion in 2 is coordinated to two dpm
chelates in a pseudo-tetrahedral environment with
NiꢀN distances ranging from 1.889(3) to 1.906(3) ꢂ
(Figure 1), as expected for such compound.[16,18]
Upon oxidation leading to the formation of a bond
between the two chelates (3), the NiII ion adopts a dis-
torted square planar environment (Figure 1). This pla-
narization of the complex is apparent when compar-
ing the angle between the two dpm moieties, 53.1
vs. 20.38 for 2 and 3, respectively. However, complex
3 is not flat but helical, as a result of the repulsion
between the two remaining aCꢀHs, with both P and
M helices present in the crystal. Owing to the strain
resulting from the formation of the bis-dpm ligand,
two NiꢀN distances are shorter than the others
(1.8527(14) and 1.8582(14) vs. 1.8920(15) and
1.8979(14) ꢂ), as described for similar complexes.[19]
For the free 2,2’-bisdpm ligand 4 (Figure 1), the four
pyrrolic rings are almost coplanar and, as for 1, an in-
tramolecular hydrogen bond is observed within the
dpm (NꢀHꢀN=2.758(3) ꢂ, 122.18). For 5, the two bis-
dpm strands are arranged into a double helix main-
tained by the two ZnII ions (Figure 1). Again, the crys-
tal is a racemate containing both P and M helices.
The ZnII centers, distant of 3.287 ꢂ, are in a distorted
tetrahedral coordination environment with the two
dpm chelates forming an angle of 56.0 and 57.58.[11]
Within a strand, the two dipyrrin moieties are tilted
by 48.7 and 55.38.
In order to investigate the formation of the tetra-
nuclear Ag2Zn2 helical species as well as the role
played by the anion Xꢀ and by the solvent, the binu-
clear ZnII helicate 5 in CHCl3 or CH2Cl2 was combined
Figure 1. Synthetic pathway for the preparation of helicate 5 (left) and crystal structures
of compounds 1–5 (right).
for the preparation of heterometallic CPs using classical coordi-
nation bonds.[13]
with AgX salts (Xꢀ =TfOꢀ, BF4ꢀ, and SbF6ꢀ) in THF or AcOEt.
Single crystals of the heterometallic architectures 6–10 were
thus obtained after few weeks and studied by X-ray diffraction
on single crystals.
We report herein that, upon combining the ZnII helicate
based on a 2,2’-bisdpm bearing peripheral benzonitrile moiet-
ies (Complex 5, Figure 1) with AgX salts, a tetranuclear core is
formed by Ag–p interactions. The latter, depending on the
nature of the anion Xꢀ and the solvents used, leads to 0-, 1-,
2-, or 3D heterometallic architectures.
In the case of TfOꢀ, upon slow diffusion of a THF solution of
Ag(TfO) into a CHCl3 solution of 5, the discrete tetranuclear
complex 6, {(5)[(Ag(TfO)(THF)]2}(CHCl3)2 was obtained. As pre-
dicted, the crystal structure of 6 (monoclinic, C2/c) revealed
that two AgI ions are complexed by the helicate 5 through
Ag–p interactions with two pyrrolic ring belonging to a p-cleft
(Figure 2). The AgꢀC distances, ranging from 2.469(3) to
2.588(3) ꢂ, are similar to those observed with mono-dpm
based metallatectons.[5] The coordination sphere of Ag+ ion is
completed by a TfOꢀ anion and a THF molecule. Interestingly,
none of the peripheral nitrile groups are coordinated to the
AgI centers, leading thus to a discrete complex. While three po-
The synthetic scheme for the preparation of the target met-
allatecton 5 is presented in Figure 1 (for experimental details
see the Supporting Information). The Ni-templated method as
reported by Scott was used for the synthesis of bis-dipyrrin
4.[14] Reaction of the benzonitrile-appended dipyrrin 1[15] with
Ni(OAc)2 afforded complex 2 in 50% yield.[16] Subsequent oxi-
dation by DDQ followed by demetallation using HCl led to the
formation of complex 3 and bis-dipyrrin 4 in 65 and 80% yield
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Figure 3. Portion of the 1D network in the structure of 7. Hydrogen atoms
and CH2Cl2 molecules have been omitted for clarity. Note that only one posi-
tion of the disordered bridging triflate anion is presented.
Figure 2. a) Top and b) side views of the tetranuclear complex in the struc-
ture of 6. Hydrogen atoms, CHCl3 solvent molecules, and benzonitrile
groups have been omitted for clarity. Note that only one of the two posi-
tions of the disordered THF is presented.
sitional isomers may be expected for 6 (Scheme 1), the struc-
tural study revealed only the presence of the 1,4 isomer
(Figure 2). Furthermore, the crystal is a racemate containing
both P and M helicates. This discrete complex was also charac-
terized by mass spectrometry showing signals corresponding
to the helicate as well as the trinuclear complex [(5)Ag]+ (Fig-
1
ure S8 in the Supporting Information). In addition, H NMR in-
vestigation revealed that, in [D8]THF solution, the decomplexa-
tion of the AgI ions occurs, since only the spectrum of the free
helicate 5 was observed.
In order to avoid the binding of THF by Ag+ ion, as ob-
served for 6, and thus generate extended networks, AcOEt was
used instead. Upon diffusion of a AcOEt solution of Ag(TfO) in
Figure 4. Top and side views of portions of the 2D network in 8. Hydrogen
atoms, anions, and solvent molecules have been omitted for clarity. Note
that only one position of the one disordered AgI ion is presented.
¯
a CH2Cl2 solution of 5, crystals (triclinic, P1) of the network 7,
{(5)[(Ag(TfO)]2} (CH2Cl2)3, were obtained. As for 6, again the 1,4
/
isomer of the tetranuclear complex (Figure 3) with AgꢀC dis-
tances ranging from 2.393(3) to 2.692(3) ꢂ is formed. Com-
pounds 6 and 7 differ by the coordination sphere of the two
Ag+ ions. Indeed, for 7, the two crystallographically independ-
ent AgI centers are both coordinated to a bridging triflate
anion, but their surrounding differs by the presence of either
a peripheral CN group of a neighboring helicate (AgꢀN=
2.304(3) ꢂ) or of a terminal TfOꢀ anion. This leads to the forma-
tion of a 1D network comprising both P and M helices
(Figure 3). As anticipated, the replacement of THF by AcOEt
leads to the self-assembly of the tetranuclear core into a coordi-
nation polymer through binding of the secondary metal cen-
ters by the peripheral nitrile group.
and 7 is formed with similar AgꢀC distances ranging from
2.420(4) to 2.688(4) ꢂ. However, the 1,3 isomer is present here.
Furthermore, the triflate anions are not anymore bound to the
AgI centers (Figure 4). Instead, the two AgI ions are coordinated
to two nitrile groups of neighboring helicates (AgꢀN=2.253(4)
to 2.392(4) ꢂ), leading thus to a 2D CP with alternating P and
M helicity (Figure 4).
In order to investigate the role played by the anion on the
assembly process, a THF solution of AgX was diffused into
a CHCl3 solution of 5, affording crystals of the coordination
polymers {(5)Ag2} (X)2 (Xꢀ =BF4ꢀ, 9; SbF6ꢀ, 10). For both iso-
/
morphous racemic crystals (monoclinic, C2/c), the 1,3 position-
al isomer of the tetranuclear core {(5)Ag2}2+ self-assembles into
a 3D network. The formation of the latter results from mutual
interconnection of consecutive helical tetranuclear moieties
through CNꢀAg bonds (Figure 5). The 3D network is porous
with cavities occupied by anions as well as by solvent mole-
It is worth noting that the synthesis of 7 also leads to the
formation of crystals of network 8, {(5)Ag2} (TfO)2(CH2Cl2) (Tri-
/
¯
clinic, P1). For the latter, again the same type of tetranuclear
motif based on Ag–p interactions as the one observed for 6
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Experimental Section
Experimental details for the synthesis of 3--10 as well as analytical
data and Figures S1–S5 in color are available in the Supporting In-
formation. CCDC-963114 (1), CCDC-963115 (2), CCDC-963116 (3),
CCDC-963117 (4), CCDC-963118 (5), CCDC-963119 (6), CCDC-
963120 (7), CCDC-963121 (8), CCDC-963122 (9), and CCDC-963123
(10) contain the supplementary crystallographic data for this
paper. These data can be obtained free of charge from The Cam-
bridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/data_
request/cif.
Acknowledgements
We thank the Universitꢀ de Strasbourg, the Institut Universi-
taire de France, the International centre for Frontier Research
in Chemistry (icFRC), CONACYT, the CNRS, and the Ministꢃre de
l’Enseignement Supꢀrieur et de la Recherche for financial sup-
port.
Keywords: Ag–p interactions · helicates · molecular tectonics ·
self-assembly · silver
[1] a) S. Kitagawa, S. Noro, T. Nakamura, Chem. Commun. 2006, 701; b) M.
Andruh, Chem. Commun. 2007, 2565; c) S. J. Garibay, J. R. Stork, S. M.
Cohen, Prog. Inorg. Chem. 2009, 56, 335; d) A. D. Burrows, CrystEng-
Comm 2011, 13, 3623; e) M. C. Das, S. Xiang, Z. Zhang, B. Chen, Angew.
Chem. 2011, 123, 10696; Angew. Chem. Int. Ed. 2011, 50, 10510; f) G.
Kumar, R. Gupta, Chem. Soc. Rev. 2013, 42, 9403.
Figure 5. Top and side view of the 3D network in 9. Hydrogen atoms and
anions have been omitted for clarity.
[2] a) M. Simard, D. Su, J. D. Wuest, J. Am. Chem. Soc. 1991, 113, 4696; b) S.
Mann, Nature 1993, 365, 499; c) M. W. Hosseini, Acc. Chem. Res. 2005,
38, 313; d) M. W. Hosseini, Chem. Commun. 2005, 5825.
[3] a) T. E. Wood, A. Thompson, Chem. Rev. 2007, 107, 1831; b) S. A. Bau-
dron, CrystEngComm 2010, 12, 2288; c) S. A. Baudron, Dalton Trans.
2013, 42, 7498.
cules. However, the latter showed important positional disor-
der and the SQUEEZE command was applied to refine the
structure.[20]
In conclusion, in order to take advantage of robust Ag–p in-
teractions in the crystalline phase, the benzonitrile appended
ZnII helicate 5 displaying both p-clefts and peripheral coordi-
nating sites was designed and prepared. Its combination with
AgX salts shows the recurrent formation of a tetranuclear
Ag2Zn2 double helical core resulting from Ag–p interactions.
Depending on the coordinating ability of Xꢀ anion and the sol-
vents used, the tetranuclear complex self-assembles into coor-
dination polymers of varying dimensionality. Although, de-
pending on the sequence of coordination events (Ag–p or Ag–
peripheral site), one may envisage two possible construction
scenarios, the Ag–p as primary event seems reasonable owing
to the rather weak binding propensity of the nitrile group and
the chelating nature of the p-clefts. This is further supported
by the formation of the discrete complex 6. It is worth noting
that the viable design principle reported purposely combines
three distinct binding modes (chelate Zn-dpm, Ag-p-cleft, Agꢀ
NC). The foregoing results not only illustrate an unprecedented
mode of assembly of helical motives and AgI ions in the crys-
talline state, but also represent rare examples of the use of hel-
icates as metallatectons for the construction of heterometallic
coordination polymers. Current investigation in our laboratory
focuses on the use of this motif with other helicates.
[4] a) S. R. Halper, S. M. Cohen, Inorg. Chem. 2005, 44, 486; b) D. L. Murphy,
M. R. Malachowski, C. F. Campana, S. M. Cohen, Chem. Commun. 2005,
5506; c) S. R. Halper, L. Do, J. R. Stork, S. M. Cohen, J. Am. Chem. Soc.
2006, 128, 15255; d) J. R. Stork, V. S. Thoi, S. M. Cohen, Inorg. Chem.
2007, 46, 11213; e) S. Garibay, J. R. Stork, Z. Wang, S. M. Cohen, S. G.
Telfer, Chem. Commun. 2007, 4881.
[5] a) D. Salazar-Mendoza, S. A. Baudron, M. W. Hosseini, Chem. Commun.
2007, 2252; b) D. Salazar-Mendoza, S. A. Baudron, M. W. Hosseini, Inorg.
Chem. 2008, 47, 766; c) D. Pogozhev, S. A. Baudron, M. W. Hosseini,
Inorg. Chem. 2010, 49, 331; d) B. Kilduff, D. Pogozhev, S. A. Baudron,
M. W. Hosseini, Inorg. Chem. 2010, 49, 11231; e) A. Bꢀziau, S. A. Baudron,
M. W. Hosseini, Dalton Trans. 2012, 41, 7227; f) A. Bꢀziau, S. A. Baudron,
D. Pogozhev, A. Fluck, M. W. Hosseini, Chem. Commun. 2012, 48, 10313;
g) A. Bꢀziau, S. A. Baudron, A. Fluck, M. W. Hosseini, Inorg. Chem. 2013,
52, 14439.
[6] a) A. E. Hill, J. Am. Chem. Soc. 1921, 43, 254; b) H. G. Smith, R. E. Rundel,
J. Am. Chem. Soc. 1958, 80, 5075; c) E. A. Hall Griffith, E. L. Amma, J. Am.
Chem. Soc. 1974, 96, 743; d) K. Shelly, D. C. Finster, Y. J. Lee, R. Scheidt,
C. A. Reed, J. Am. Chem. Soc. 1985, 107, 5955; e) M. Munakata, L. P. Wu,
G. L. Ning, Coord. Chem. Rev. 2000, 198, 171; f) S. V. Lindeman, R. Ra-
thore, J. K. Kochi, Inorg. Chem. 2000, 39, 5707; g) E. L. Elliott, G. A.
Hernꢄndez; A. Linden, J. S. Siegel, Org. Biomol. Chem. 2005, 3, 407; A.
Linden, J. S. Siegel, Org. Biomol. Chem. 2005, 3, 407; h) T. C. W. Mak, L.
Zhao, Chem. Asian J. 2007, 2, 456; i) J. Burgess, P. J. Steel, Coord. Chem.
Rev. 2011, 255, 2094.
[7] C.-F. Chang, C.-H. Wang, H.-C. Lu, L.-S. Kan, I. Chao, W. H. Chen, A.
Kumar, L. Lo, M. A. C. dela Rosa, C.-H. Hung, Chem. Eur. J. 2011, 17,
11332.
[8] a) A. Thompson, D. Dolphin, Org. Lett. 2000, 2, 1315; b) A. Al-Sheikh Ali,
R. E. Benson, S. Blumentritt, T. S. Cameron, A. Linden, D. Wolstenholme,
A. Thompson, J. Org. Chem. 2007, 72, 4947.
Chem. Eur. J. 2014, 20, 2449 – 2453
www.chemeurj.org
2452
ꢁ 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim

Communication
[9] a) M. Ikeda, T. Tanida, M. Takeuchi, S. Shinkai, Org. Lett. 2000, 2, 1803;
b) M. Ikeda, M. Takeuchi, S. Shinkai, F. Tani, Y. Naruta, S. Sakamoto, K. Ya-
maguchi, Chem. Eur. J. 2002, 8, 5541.
[10] a) H. Maeda, Eur. J. Org. Chem. 2007, 5313; b) M. Brçring in Handbook of
Porphyrin Science, Vol. 8, 2010, p. 343.
Huang, Chem. Eur. J. 2008, 14, 8916; d) E. Terazzi, L. Guenꢀe, J. Varin, B.
Bocquet, J.-F. Lemonnier, D. Emery, J. Mareda, C. Piguet, Chem. Eur. J.
2011, 17, 184; e) X. Xi, Y. Fang, T. Dong, Y. Cui, Angew. Chem. 2011, 123,
1186; Angew. Chem. Int. Ed. 2011, 50, 1154.
ˇ
´
[14] H. S. Gill, I. Finger, I. Bozidarevic, F. Szydlo, M. J. Scott, New J. Chem.
[11] a) G. Struckmeier, U. Thewalt, J.-H. Furhop, J. Am. Chem. Soc. 1976, 98,
278; b) Y. Zhang, A. Thompson, S. J. Rettig, D. Dolphin, J. Am. Chem. Soc.
1998, 120, 13537; c) R. G. Khoury, L. Jaquinod, K. M. Smith, Tetrahedron
1998, 54, 2339; d) A. Thompson, D. Dolphin, J. Org. Chem. 2000, 65,
7870; e) Q. Chen, Y. Zhang, D. Dolphin, Tetrahedron Lett. 2002, 43, 8413;
f) L. Yang, Y. Zhang, Q. Chen, J. S. Ma, Monatsh. Chem. 2004, 135, 223;
g) T. E. Wood, N. D. Dalgeish, E. D. Power, A. Thompson, X. Chen, Y. Oka-
moto, J. Am. Chem. Soc. 2005, 127, 5740; h) T. E. Wood, A. C. Ross, N. D.
Dalgeish, E. D. Power, A. Thompson, X. Chen, Y. Okamoto, J. Org. Chem.
2005, 70, 9967; i) M. Brçring, S. Link, C. D. Brandt, E. Cꢅnsul Tejero, Eur. J.
Inorg. Chem. 2007, 1661; j) T. Hashimoto, T. Nishimura, J. M. Lin, D. Khim,
H. Maeda, Chem. Eur. J. 2010, 16, 11653; k) H. Maeda, T. Nishimura, R.
Akuta, K. Takaishi, M. Uchiyama, A. Muranaka, Chem. Sci. 2013, 4, 1204.
[12] a) J.-M. Lehn, A. Rigault, J. Siegel, J. Harrowfield, B. Chevrier, D. Moras,
Proc. Natl. Acad. Sci. USA 1987, 84, 2565; b) C. Piguet, G. Bernardinelli,
G. Hopfgartner, Chem. Rev. 1997, 97, 2005; c) A. Williams, Chem. Eur. J.
1997, 3, 15; d) M. Albrecht, Chem. Soc. Rev. 1998, 27, 281; e) J.-M. Lehn,
Chem. Eur. J. 2000, 6, 2097; f) M. Albrecht, Chem. Rev. 2001, 101, 3457;
g) T. Kreickmann, F. E. Hahn, Chem. Commun. 2007, 1111; h) H. Miyake,
H. Tsukube, Chem. Soc. Rev. 2012, 41, 6977.
2005, 29, 68.
[15] a) S. J. Vigmond, M. C. Chang, K. M. R. Kallury, M. Thompson, Tetrahedron
Lett. 1994, 35, 2455; b) P. D. Rao, S. Dhanalekshmi, B. J. Littler, J. S. Lind-
sey, J. Org. Chem. 2000, 65, 7323.
[16] Q. Miao, J.-Y. Shin, B. O. Patrick, D. Dolphin, Chem. Commun. 2009, 2541.
[17] a) J.-Y. Shin, B. O. Patrick, D. Dolphin, CrystEngComm 2008, 10, 960; b) J.-
Y. Shin, B. O. Patrick, B. S. Son, J. R. Hahn, D. Dolphin, Bull. Korean Chem.
Soc. 2010, 31, 1004; c) S. A. Baudron, D. Salazar-Mendoza, M. W. Hossei-
ni, CrystEngComm 2009, 11, 1245; d) D. Pogozhev, S. A. Baudron, M. W.
Hosseini, Dalton Trans. 2011, 40, 437.
[18] a) C. Brꢆckner, V. Karunaratne, S. J. Rettig, D. Dolphin, Can. J. Chem.
1996, 74, 2182; b) D. Pogozhev, S. A. Baudron, M. W. Hosseini, CrystEng-
Comm 2010, 12, 2238.
[19] a) M. Brçring, C. D. Brandt, J. Lex, H.-U. Humpf, J. Bley-Esrisch, J.-P. Gis-
selbrecht, Eur. J. Inorg. Chem. 2001, 2549; b) M. Brçring, C. D. Brandt, J.
Bley-Esrisch, J.-P. Gisselbrecht, Eur. J. Org. Chem. 2002, 910; c) M. Brçr-
ing, C. D. Brandt, Monatsh. Chem. 2002, 133, 623; d) M. Brçring, S. Link,
M. Cordes, C. D. Brandt, Z. Anorg. Allg. Chem. 2007, 633, 211.
[20] A. L. Spek, PLATON, The University of Utrecht, Utrecht, The Netherlands,
1999.
[13] a) P. Cucos, M. Pascu, R. Sessoli, N. Avarvari, F. Pointillart, M. Andruh,
Inorg. Chem. 2006, 45, 7035; b) S. N. Semenov, A. Y. Rogachev, S. V. Eli-
seeva, C. Pettinari, F. Marchetti, A. A. Drozdov, S. I. Troyanov, Chem.
Commun. 2008, 1992; c) S.-Z. Zhan, M. Li, J.-Z. Hou, J. Ni, D. Li, X.-C.
Received: November 4, 2013
Published online on January 30, 2014
Chem. Eur. J. 2014, 20, 2449 – 2453
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