Single atom coordination in a manganese-cobalt bi-metallic framework on graphene: geometric and electronic structures

Manganese tetra-pyridyl-porphyrins are found to self-organize in an ordered monolayer on graphene. Moreover, post deposition of cobalt ad-atoms steers the geometric reordering of the layer, yielding the formation of a self-assembled bimetallic network, where both Mn and Co are tetra-coordinated with nitrogen. While manganese shifts from Mn(ii) towards the +2/+3 oxidation state range, depending on the local Co concentration and not reaching a full Mn(iii) configuration, pyridinic cobalt is stabilized in the rarer +1 oxidation state. The actual geometric and electronic structures of the framework are defined by lateral interactions, dominating over the weaker network-graphene bonding.