Complexes of a bis-bidentate ligand with d10 ions:: a mononuclear complex with Ag(I), and a tetrahedral cage complex with Zn(II) which encapsulates a fluoroborate anion

Complexes of the bis-bidentate ligand 2,3-bis[{3-(2-pyridyl)-pyrazol-1-yl]methyl]naphthalene (L-2) with Ag(I) and Zn(II) have been prepared and structurally characterised. In [Ag(L-2)] [ClO4] both bidentate pyrazolyl-pyridine arms of L-2 interact with the same Ag(I) centre, which has two short Ag-N bonds and two much longer, weaker interactions such that the coordination is best described as linear and bidentate. In contrast, in [Zn-4(L-2) (BF4)][BF4](7) the ligands L-2 act as bis-bidentate bridges; the structure consists of a tetrahedral cage of Zn(II) ions with a bridging ligand L-2 along each of the six edges. The cavity at the centre of this three-dimensional tetrahedral cage accommodates a tetrafluoroborate anion which is completely encapsulated, and inverted with respect to the Zn-4 tetrahedron. The F atoms of this encapsulated anion are involved in close F-HC contacts with parts of the bridging ligands. B-11 and F-19 NMR spectra show that the encapsulated anion does not exchange with free tetrafluoroborate anions in MeCN solution, e ven up to 70 degreesC. (C) 2003 Elsevier Science Ltd. All rights reserved.