Fourier-transform infrared study of short-lived highly reduced dithiolene complexes by potential-modulation spectroelectrochemical techniques

The reduction of [M(mnt)3]3–(M = V, Mo or Re; mnt = maleonitriledithiolate) has been examined by potential-modulation spectroelectrochemical techniques. Despite the highly reducing potentials required to effect the reductions (–1.57 to –2 V) and the highly unstable character of the reduction products the values of ν(CN) have been obtained for [M(mnt)3]4–(M = V, Re or Mo)(2164, 2133 and 2134 cm–1 respectively). The sensitivity of the ν(CN) values to the identity of the metal for [M(mnt)3]4– is greater than that found for the corresponding trianions suggesting an increased metal contribution to the frontier orbitals. The application of potential-modulation techniques to the examination of bulk solution species is described and shown to offer significant advantages for highly reactive electrochemically generated species.