Ranking the Stability of Transition-Metal Complexes by On-Surface Atom Exchange

Abstract

Surface-adsorbed macrocycles exhibit a number of interesting physical and chemical properties; many of them are determined by their transition-metal centers. The hierarchical exchange of the central metal atom in such surface-adsorbed complexes is demonstrated, specifically in the porphyrin-like macrocycle pyrphyrin adsorbed on Cu(111). Using scanning tunneling microscopy and X-ray photoelectron spectroscopy, we show that Cu as central metal atom is easily exchanged with Ni or Fe atoms supplied in trace amounts to the surface. Atom exchange of Ni centers with Fe atoms also occurs, with moderate yield. These results allow ranking the stability of the surface-adsorbed Cu, Ni, and Fe complexes. The fact that the atom exchange occurs at 423 K shows that surface-adsorbed macrocycles can be surprisingly easily transformed.

1D Coordination π–d Conjugated Polymers with Distinct Structures Defined by the Choice of the Transition Metal: Towards a New Class of Antiaromatic Macrocycles

“…[55] In contrast, the Fe2p 3/2 binding energy of FeQDI/Au(111) (707.3 eV) is surprisingly low for aF e II ion. Thes ame effect, that is,high Ni and low Fe binding energy,has been reported for {Fe,Ni}porphyrins,p hthalocyanines and related compounds [56] and is interpreted as ap artial shift of electron density from the substrate to the metal ion, in line with the original explanation of this effect. [57][58][59] Unfortunately,b ecause of the overwhelming substrate signals we cannot study Cu XP spectra of Cu 2 QDI/Cu(111).…”

1D Coordination π–d Conjugated Polymers with Distinct Structures Defined by the Choice of the Transition Metal: Towards a New Class of Antiaromatic Macrocycles

“…In contrast, the Fe2p 3/2 binding energy of FeQDI /Au(111) (707.3 eV) is surprisingly low for a Fe II ion. The same effect, that is, high Ni and low Fe binding energy, has been reported for {Fe,Ni}porphyrins, phthalocyanines and related compounds [56] and is interpreted as a partial shift of electron density from the substrate to the metal ion, in line with the original explanation of this effect [57–59] . Unfortunately, because of the overwhelming substrate signals we cannot study Cu XP spectra of Cu 2 QDI /Cu(111).…”

On-surface transmetalation of metalloporphyrins

“…Recently, the hierarchical exchange of Cu by additionally supplied Ni and Fe in organic macrocycles was reported at elevated temperatures. 29 Whereas these exchange reactions can be controlled regarding the exchanging metal centres, the reaction yield appears less controllable. Furthermore, so far systems with only one coordination environment, the porphyrin macrocycle, were investigated, limiting the exchange to this one site.…”