Infrared spectroelectrochemical studies have been conducted on the series of complexes [M(mnt)₂]^n–(mnt =cis-1,2-dicyanoethylene-1,2-dithiolate; M = Fe or Au, n= 1; M = Co, Ni, Cu, Pd or Pt, n= 2). The v(CN) values for related mono-, di-, and (for M = Cu or Au) tri-anions indicate that the extent of the metal contribution to the π orbital, which is delocalised over the mnt ligands, is directly comparable to that for the tri- and tetra-anionic forms of related tris(mnt) complexes, [M(mnt)₃]^n–(n= 3 or 4). Previous ESR-based assignments of the singly occupied molecular orbital for [M(mnt)₂]^2–, M = Cu or Au, to predominantly metal (Cu)- or ligand (Au)-based orbitals are supported by the trends in v(CN). For [M(mnt)₂]^–, M = Fe or Co, dimer formation and/or ligand association occurs to a significant extent in solution. While these reactions lead to irreversible electrochemical behaviour, well defined spectroelectrochemical results are obtained which are discussed in terms of the kinetics of the reaction and the electronic structure of the products.