Use of [SbF6]- to Isolate Cationic Copper and Silver Adducts with More than One Ethylene on the Metal Center

A cationic tris(ethylene)copper(I) and tris(ethylene)silver(I) adduct has been isolated using hexafiuoroantimonate counterion. X-ray crystallographic analysis shows that the metal atom in these adducts coordinates to three ethylene molecules in a trigonal planar fashion, forming a spoke-wheel arrangement. In [M(C2H4)(3)][SbF6] adducts (M = Cu, Ag, Au), the average M-C distances of 2.189 angstrom for Cu and 2.410 angstrom for Ag can be compared with the corresponding distance of 2.268 angstrom for Au and show that the copper(I) complex has the shortest while the silver adduct displays the longest M-C distances. These agree well with the computed values (2.172, 2.408, and 2.308 angstrom for Cu, Ag, and Au analogues, respectively) and follow the same trend as the covalent radii of M(I). Structural data on [mu(3)-Cl{Cu(C2H4)(2)}(3)][SbF6]2(,) which features bis(ethylene)copper(I) moieties, are also presented. It has a trigonal planar Cu3Cl core with a triply bridging chloride ion bonded to three trigonal planar copper centers. Ethylene molecules are bonded in an eta(2)-fashion. The data indicate that while these [M(C2H4)(3)](+) complexes may be primarily electrostatic in their metal-ethylene binding, there remains an important covalent contribution, particularly for the copper and gold congeners.