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ABSTRACT: Reaction of a tris-bidentate ligand L(1) (which can cap one triangular face of a metal polyhedron), a bis-bidentate ligand L(2) (which can span one edge of a metal polyhedron), and a range of M(2+) ions (M = Co, Cu, Cd), which all have a preference for six coordination geometry, results in assembly of the mixed-ligand polyhedral cages [M12(mu(3)-L(1))4(mu-L(2))12](24+). When the components are combined in the correct proportions [M(2+):L(1):L(2) = 3:1:3] in MeNO2, this is the sole product. The array of 12 M(2+) cations has a cuboctahedral geometry, containing six square and eight triangular faces around a substantial central cavity; four of the eight M3 triangular faces (every alternate one) are capped by a ligand L(1), with the remaining four M3 faces having a bridging ligand L(2) along each edge in a cyclic helical array. Thus, four homochiral triangular {M3(L(2))3}(6+) helical units are connected by four additional L(1) ligands to give the mixed-ligand cuboctahedral array, a topology which could not be formed in any homoleptic complex of this type but requires the cooperation of two different types of ligand. The complex [Cd3(L(2))3(ClO4)4(MeCN)2(H2O)2](ClO4)2, a trinuclear triple helicate in which two sites at each Cd(II) are occupied by monodentate ligands (solvent or counterions), was also characterized and constitutes an incomplete fragment of the dodecanuclear cage comprising one triangular {M3(L(2))3}(6+) face which has not yet reacted with the ligands L(1). (1)H NMR and electrospray mass spectrometric studies show that the dodecanuclear cages remain intact in solution; the NMR studies show that the Cd 12 cage has four-fold (D2) symmetry, such that there are three independent Cd(II) environments, as confirmed by a (113)Cd NMR spectrum. These mixed-ligand cuboctahedral complexes reveal the potential of using combinations of face-capping and edge-bridging ligands to extend the range of accessible topologies of polyhedral coordination cages.
Journal of the American Chemical Society 10/2008; 130(35):11641-9. · 9.91 Impact Factor
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Berichte der deutschen chemischen Gesellschaft 08/2007; 2007(30):4770 - 4780. · 2.94 Impact Factor
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ABSTRACT: The addition of enantiopure TRISPHAT anions to chiral cationic cages of type [Co(4)(L)(6)(BF(4))](7+) leads to the enantiodifferentiation of the ligands of the racemic salts and, even more effectively, of the achiral tetrafluoroborate anion trapped inside.
Chemical Communications 04/2007; · 6.17 Impact Factor
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ABSTRACT: Incorporation of ligands containing substituted naphthalene cores into coordination cages results in extensive aromatic pi-stacking between ligands; this results in a red-shifted 'excimer-like' luminescence component from the naphthyl groups compared to the free ligands, which is diagnostic of, and can be used to monitor, cage assembly.
Dalton Transactions 11/2006; · 3.84 Impact Factor
