Spin Crossover in the {Fe(pz)[Pt(CN)4]} Metal–Organic Framework upon Pyrazine Adsorption

• Published in: The journal of physical chemistry letters 2016-10, Vol.7 (19), p.4022-4026
• Main Authors: Pham, C. Huy, Paesani, Francesco
• Format: Article
• Language: English
• ISSN: 1948-7185; 1948-7185
• DOI: 10.1021/acs.jpclett.6b01788

The spin-crossover behavior of the {Fe­(pz)­[Pt­(CN)4]} metal–organic framework (MOF) upon pyrazine adsorption is investigated through hybrid Monte Carlo/molecular dynamics (MC/MD) simulations. In contrast to previous theoretical studies, which reported a transition temperature of ∼140 K, the present MC/MD simulations predict that the high-spin state is the most stable state at all temperatures, in agreement with the experimental observations. The MC/MD simulations also indicate that the pyrazine molecules adsorbed in the MOF pores lie nearly parallel but staggered by 60° relative to the pyrazine ligands of the framework. The analysis of the magnetization curve as a function of the temperature demonstrates that the staggered configuration assumed by the guest pyrazine molecules within the framework is responsible for the stabilization of the high-spin state. Both the guest pyrazine molecules and the pyrazine ligands of the framework are effectively locked into the minimum-energy configuration and do not display any rotational mobility.