[CuL2][ClO4] and [AgL2][BF4], where L = 6,6 '-dibromo-2,2 '-bipyridine

The complexes bis(6,6'-dibromo-2,2'-bipyridine-N,N')copper(I) perchlorate, [Cu(C10H6Br2N2)(2)]ClO4, and bis(6,6'-dibromo-2,2'-bipyridine-N,N')silver(I ) tetrafluoroborate, [Ag(C10H6Br2N2)(2)]BF4, both contain four-coordinate p seudo-tetrahedral metal centres, in which the two bidentate chelating ligan ds are nearly mutually perpendicular; the average dihedral angle between th e two MN2 planes is 87.9 degrees for M = Cu but only 75 degrees for M = Ag, which reflects the lesser inter-ligand steric interactions in the silver(I ) complex, arising from the greater metal-ligand bond distances. For both c omplexes, the crystal packing is dominated by intermolecular Br ... Br inte ractions.