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Quantum Chemical Modeling of Pressure-Induced Spin Crossover in Octahedral Metal-Ligand Complexes |
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| Authors: | Prof. Dr. Tim Stauch Dr. Romit Chakraborty Prof. Dr. Martin Head-Gordon |
| Affiliation: | 1. University of Bremen, Institute for Physical and Theoretical Chemistry, Leobener Str. NW2, 28359 Bremen, Germany;2. Kenneth S. Pitzer Center for Theoretical Chemistry, Department of Chemistry, University of California, Berkeley, California, 94720 United States of America Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, 94720 United States of America These authors contributed equally to this work;3. Kenneth S. Pitzer Center for Theoretical Chemistry, Department of Chemistry, University of California, Berkeley, California, 94720 United States of America Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, 94720 United States of America |
| Abstract: | Spin state switching on external stimuli is a phenomenon with wide applicability, ranging from molecular electronics to gas activation in nanoporous frameworks. Here, we model the spin crossover as a function of the hydrostatic pressure in octahedrally coordinated transition metal centers by applying a field of effective nuclear forces that compress the molecule towards its centroid. For spin crossover in first-row transition metals coordinated by hydrogen, nitrogen, and carbon monoxide, we find the pressure required for spin transition to be a function of the ligand position in the spectrochemical sequence. While pressures on the order of 1 GPa are required to flip spins in homogeneously ligated octahedral sites, we demonstrate a fivefold decrease in spin transition pressure for the archetypal strong field ligand carbon monoxide in octahedrally coordinated Fe2+ in [Fe(II)(NH3)5CO]2+. |
| Keywords: | density functional theory metal−ligand complexes pressure quantum chemical modeling spin crossover |