A. J. Metherell, M. Ward
Oct 3, 2018
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Journal
Supramolecular Chemistry
Abstract
Abstract The ligand L an contains two bidentate chelating pyrazolyl-pyridine termini connected to a central aminophenyl ring. In [Ag3(L an )2](ClO4)3 each ligand coordinates in a pentadentate 2+1+2 manner, connecting all three Ag(I) ions. In contrast, in the octanuclear cubic coordination cage [Co8(L an )12][BF4]16 each L an coordinates as a bis(pyrazolyl-pyridine) tetradentate chelate, with the externally-directed amine groups not coordinated. From its 1H NMR spectrum this cage has the S 6 symmetric structure containing two fac and six mer tris-chelate Co(II) centres of other octanuclear cages. Slow crystallisation afforded [Co8(L an )12Na][BF4]17, with S 4 symmetry arising from four fac and four mer tris-chelate Co(II) centres which alternate; the central cavity accommodates an Na+ cation and four fluoroborate anions which form a {Na(BF4)4}3– guest. The {Na(BF4)4}3– guest forms F•••HN hydrogen bonds through the cage windows with exterior amine groups. Rearrangement of the cage structure from S 6 to S 4 symmetry appears to facilitate inclusion of the fourfold symmetric guest.