5.1 Experimental details

The STM experiments were performed at 78 K in an ultra-high-vacuum system consisting of an analysis chamber (with a base pressure of 2 × 10-11 mbar) and a preparation chamber (5 × 10-11 mbar). An electrochemically etched polycrystalline tungsten tip was used to record STM images in constant current mode. The voltage V sample corresponds to the sample bias with respect to the tip. No drift corrections have been applied to any of the STM images presented herein.

The Ag(111) crystal (Surface Preparation Laboratory) was cleaned in situ by repeated cycles of argon ion sputtering (Ek = 0.8keV) and annealing at 820 K. The substrate cleanliness was verified by STM and LEED before deposition of the MnClTPP. MnClTPP was synthesized according to a published procedure [212] by Dr Natalia Sergeeva in the School of Chemistry, TCD. The molecules were evaporated in a preparation chamber isolated from the STM chamber at a rate of about 0.2 ML per minute from a tantalum crucible in a homemade deposition cell operated at a temperature of approximately 600 K. The total pressure during porphyrin deposition was in the 10-10 mbar range. Before evaporation, the NiDPP powder was degassed for about 10 hours to remove water vapour.

XAS and XPS measurements were performed at the D1011 beamline at MAX II storage ring in Lund, Sweden by Dr Sergey Krasnikov and Dr Tony Cafolla, and their work and guidance are gratefully acknowledged. The XPS spectra were measured with a Scienta SES-200 electron energy analyzer. The kinetic energy resolution was set to 100 meV for the Cl 2p spectra. The photon energy resolution was set to 150 meV at the Mn L3-edge (640 eV). The XAS spectra were recorded in the partial electron yield mode (U = -100V) by a multichannel plate detector and normalized to the background curves recorded from the clean substrate.

DFT calculations were performed under the guidance of Dr Olaf Lübben using the Vienna Ab initio Simulation Package (VASP) program. VASP implements a projected augmented basis set (PAW) [70] and periodic boundary conditions. The electron exchange and correlation was simulated by generalised gradient approximation (GGA) pseudopotentials with a Perdew-Burke-Ernzerhof (PBE) exchange-correlation density functional [62]. A single k-point (Γ) was used for all calculations to sample the Brillouin zone. The applied energy cut-off was 400 eV. The global break condition for the electronic self-consistent loops was set to a total energy change of less than 1 × 10-4 eV, and all conformations were fully relaxed (forces < 0.01eV/Ċ ).