Synthesis and characterization of Lewis-base adducts of 1,1,1,5,5,5-hexafluoroacetylacetonatosilver(I)

Abstract

The compounds [{Ag(hfacac)}_mL_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 ¹H and ¹³C 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 viathe S atoms. The silver has a severely distorted tetrahedral geometry with an enlarged S–Ag–S angle [149.6(1)°] and a reduced O–Ag–O angle [74.4(2)°] which is characteristic of (β-diketonato)bis(ligand)metal compounds where M = Ag or Cu.