Stabilization of high-spin Mn ions in tetra-pyrrolic configuration on copper

By means of Mn-Cu transmetalation, we incorporated Mn atoms in an array of TCNQ (7,7,8,8-tetracyanoquinodimethane) grown on Cu(100), forming a long range ordered and commensurate metal-organic coordination network (MOCN). Preliminary Sn alloying of the Cu(100) surface allowed us to control the degree of substrate reactivity, thus preventing the chemical interaction of the Mn-TCNQ MOCN with the substrate. Mn2+ ions are stabilized in an artificial tetra-pyrrolic coordination, which mimics the macrocyle configuration of Mn-phthalocyanines/porphyrins. X-ray absorption spectroscopy at the Mn L-2,L-3-edge indicates that the Mn ions are in a high-spin state (S = 5/2), in agreement with DFT + U calculations which also shows that the electronic structure of this Mn-TCNQ MOCN is very similar to that of the corresponding unsupported MOCN.