Modelling studies show that the anion pentacyanocyclopentadienide, 1, can complex linearly coordinating cations such as silver(I) and copper(I) to form a spheroidal complex [M30(1)12]18+ with minimum distortion. The anion 1 complexes transition metal ions to give species which appear to be polymers in the solid state. The structure of Ag(1) was determined by powder diffraction and shows a one-dimensional polymeric structure with three coordinate AgI and two CN functions of the ligand 1 non-coordinated. No evidence for the formation of the spheroidal complex was found.