Cyanido‐Bridged Fe II –M I Dimetallic Hofmann‐Like Spin‐Crossover Coordination Polymers Based on 2,6‐Naphthyridine

Two new 3D spin‐crossover (SCO) Hofmann‐type coordination polymers {Fe(2,6‐naphthy)[Ag(CN) 2 ][Ag 2 (CN) 3 ]} ( 1 ; 2,6‐naphthy = 2,6‐naphthyridine) and {Fe(2,6‐naphthy)[Au(CN) 2 ] 2 } · 0.5PhNO 2 ( 2 ) were synthesized and characterized. Both derivatives are made up of infinite stacks of {Fe[Ag(CN) 2 ] 2 [Ag 2 (CN) 3 ]} n and {Fe[Au(CN) 2 ] 2 } n layered grids connected by pillars of 2,6‐naphthy ligands coordinated to the axial positions of the Fe II centers of alternate layers. The in situ generated [Ag 2 (CN) 3 ] – linkers define wide rectangular windows that favor the interpenetration of three identical 3D networks, strong argentophilic interactions between them, and the generation of a densely packed structure without accessible void spaces. In contrast, the smaller rhombus‐shaped window in 2 affords a structure made up of doubly interpenetrated 3D networks with strong aurophilic interactions between them and accessible voids partially occupied by nitrobenzene molecules. Compound 1 displays a relatively abrupt two‐step SCO in the temperature interval 150–215 K, whereas 2 features an incomplete one‐step SCO behavior ( T 1/2 = 166 K) that extends over 150 K.