SYNTHESIS AND CHARACTERIZATION OF LEWIS-BASE ADDUCTS OF 1,1,1,5,5,5-HEXAFLUOROACETYLACETONATOSILVER(I)

The compounds [{Ag(hfacac)}(m)L(n)] [hfacac = 1,1,1,5,5,5-hexafluoroacetylacetonate, L = norbornadiene (nbd), m = 2, n = 1; L = SMe2, SEt2, SPrn2 or SBun2, m = 1, n = 1; L = 1,4-oxathiane, m = 1, n = 1 or 2] were prepared by the reaction between the Lewis bases, L, Hhfacac and Ag2O in the appropriate ratios. In addition, the intermediate [{Ag(hfacac)}2(H2O)], formed by the reaction of Ag2O with 2 equivalents of Hhfacac in the absence of L was isolated. These species were characterized by H-1 and C-13 NMR and Fourier-transform IR spectroscopy and by combustion elemental analysis. Three examples were structurally characterized by single-crystal X-ray diffraction. The compound [{Ag(hfacac)}2(H2O)] is oligomeric by virtue of intermolecular hydrogen bonding between the co-ordinated water molecule and the oxygen atoms in the hfacac ligand in an adjacent molecule. In addition there is a bonding interaction between the methine carbon in the hfacac ring of one molecule and the silver centre in an adjacent molecule. The compound [{Ag(hfacac)}2(nbd)] is dimeric leading to a tetranuclear molecular unit in which the hfacac ligands both chelate and bridge, with unidentate nbd ligands. The compound [Ag(hfacac)(C4H8OS)2] is monomeric in the solid state with the 1,4-oxathiane ligands co-ordinated to the silver(I) centre exclusively via the S atoms. The silver has a severely distorted tetrahedral geometry with an enlarged S-Ag-S angle [1 49.6(l )-degrees] and a reduced O-Ag-0 angle [74.4(2)-degrees] which is characteristic of (beta-diketonato)bis(ligand)metal compounds where M = Ag or Cu.