Enhanced Interplay between Host-Guest and Spin-Crossover Properties through the Introduction of an N Heteroatom in 2D Hofmann Clathrates

[EN] Controlled modulation of the spin-crossover (SCO) behavior through the sorption-desorption of invited molecules is an extensively exploited topic because of its potential applications in molecular sensing. For this purpose, understanding the mechanisms by which the spin-switching properties are altered by guest molecules is of paramount importance. Here, we show an experimental approach revealing a direct probe of how the interplay between SCO and host-guest chemistry is noticeably activated by chemically tuning the host structure. Thus, the axial ligand 4-phenylpyridine (4-PhPy) in the 2D Hofmann clathrates {Fe(4-PhPy)(2) [M(CN)(4)]} (PhPyM; M = Pt, Pd) is replaced by 2,4-bipyridine (2,4-Bipy), resulting in the isomorphous com- pounds {Fe(2,4-Bipy)(2) [M(CN)(4)]) (BipyM; M = Pt, Pd), which basically differ from the former in that they have a noncoordinated N heteroatom in the ancillary aromatic substituent, i.e., 2-pyridyl instead of phenyl. Our chemical, magnetic, calorimetric, and structural characterizations demonstrate that this subtle chemical composition change provokes outstanding modifications not only in the capability to adsorb small guests as water or methanol but also in the extent to which these guests affect the SCO characteristics.This work was supported by the Spanish Ministerio de Ciencia e Innovacion (MICINN) and FEDER funds (Grant PID2019-106147GB-I00), Unidad de Excelencia Maria de Maeztu (Grants MDM2015-0538-18-2 and CEX2019-000919-M), and EU Framework FET-OPEN project COSMICS (Grant Agreement 766726). R.T.-C. and M.M.-S. thank the MICINN for a predoctoral grant.Meneses-Sánchez, M.; Turo-Cortés, R.; Bartual-Murgui, C.; Da Silva, I.; Muñoz Roca, MDC.; Real, JA. (2021). Enhanced Interplay between Host-Guest and Spin-Crossover Properties through the Introduction of an N Heteroatom in 2D Hofmann Clathrates. Inorganic Chemistry. 60(16):11866-11877. https://doi.org/10.1021/acs.inorgchem.1c019251186611877601