Effect of metal-metal interactions on electron transfer: An STM study of one-dimensional metal string complexes

Linear metal string complexes of [MnL4(NCS)2] (Scheme 1, M = NiII, CoII, or CrII; n = 3 or 5; L = dpa- or tpda2- where dpa- is dipyridylamido anion and tpda2- is tripyridyldiamido dianion) are studied for the fundamental understanding of the effect of inter-nuclei interactions on electron transfer (ET). The metal strings are isolated within n-alkanethiol monolayers and the properties of ET through various metal strings are differentiated by scanning tunneling microscopy. Although very similar in physical dimension, their apparent heights against the same alkanethiol background are significantly different. The discrepancy is ascribed to electron localization-delocalization among the metal centers.