Year: 2026
Type: article
Abstract: High Resolution Image Download MS PowerPoint Slide Hofmann-type Fe(II) frameworks, [Fe(pz)M(CN) 4 ] (pz = pyrazine; M = Pd, Pt), exhibit a dual-mode response to ammonia, arising from its strong Lewis basicity. Short-term NH 3 exposure produces reversible clathrates ( 1-Pd@NH 3, 1-Pt@NH 3 ) that change from orange to pale yellow, with the parent framework preserved. In these clathrates, spin-crossover behavior is strongly modulated, with transition temperatures shifted by up to 150 K and partial stabilization of the high-spin state. Prolonged exposure induces irreversible pyrazine-to-ammonia substitution at Fe(II) axial sites, forming red, diamagnetic phases ([Fe(NH 3 ) 2 M(CN) 4 ]·2H 2 O; M = Pd ( 2 ), Pt ( 3 )). Substitution kinetics are metal-dependent: the Pd framework transforms rapidly (∼1 h), consistent with slightly longer Pd–C/N bonds and more labile Fe–N(pz) coordination, whereas the Pt framework transforms more slowly (∼24 h), correlating with shorter Pt–C/N bonds and higher lattice rigidity. Other polar guests (H 2 O, alcohols, pyridine) induce only reversible clathrate formation, highlighting the unique chemical reactivity of NH 3 . These results establish clear links between guest Lewis basicity, metal–ligand covalency, framework stability, and functional response, demonstrating how host–guest chemistry can be leveraged to precisely tune structural, electronic, and magnetic properties in heterometallic coordination frameworks.
Source: Inorganic Chemistry
Language: English
Subfield: Inorganic Chemistry
Field: Chemistry
Domain: Physical Sciences
Open Access status: hybrid
Estimated APC paid: $4,500
Awards: G2103759246, G3399646272, G4486377272
OpenAlex ID: W7146997894