New family of Hofmann-like coordination polymers constructed with imidazole ligands and associated with spin crossover and anisotropic thermal expansions

Abstract

Instead of conventional utilized pyridine derivatives ligands for Hofmann-like SCO structure, five-membered aromatic ring ligands afforded a new Hofmann-like compounds series Fe(L)2[Ni(CN)4] (L = imidazole (1), 1-Methylimidazole (2)). The synthesis,...

Fe(L)2[M(CN)4] with L = 4-Ethyl Isonicotinate and M = Ni, Pd, Pt.─A Series of Hofmann-Type Frameworks with Spin Crossover: The Dominant Role of the Fe–NC Coordination Bond

“…Cyanide-based coordination polymers form a vast family of solids where the SCO has been reported, e.g., ferrous dicyanides, − tetracyanides, ,,− ,− hexacyanides, − octacyanides, − and nitroprussides. − Except for ferrous hexacyanometallates, where the SCO is observed for the iron atom with a coordination sphere formed by six N ends of CN ligands, − in the remaining series, two organic molecules (L) participate in the coordination environment of the iron atom, Fe­(L) 2 (N CN ) 4 , resulting an MOF-type framework. The tetracyanide-based series, Fe­(L) n [M­(CN) 4 ] with n = 1,2, and M = Ni, Pd, Pt, and their nitroprusside analogs, Fe­(L) n [Fe­(CN) 5 NO], are known as Hofmann-like coordination polymers.…”

Surface stabilisation of the high-spin state of Fe(ii) spin-crossover complexes

“…29–31 While there are multiple Fe( ii ) SCO complexes, the model Fe( ii ) SCO compound Fe(phen) 2 (NCS) 2 and the Hofmann-like Fe( ii ) SCO complexes have gathered quite a lot of research interest over the past two decades, in particular. 4,23,32–36…”

“…[29][30][31] While there are multiple Fe(II) SCO complexes, the model Fe(II) SCO compound Fe(phen) 2 (NCS) 2 and the Hofmann-like Fe(II) SCO complexes have gathered quite a lot of research interest over the past two decades, in particular. 4,23,[32][33][34][35][36] Since Fe(II) experiences a considerable electronic change with a spin-state transition 37 (the occupancy diagram for the LS and HS electronic configurations is presented in Fig. 1a), these transitions can be easily detected by monitoring the temperature-dependent changes in the Fe 2p core-level XPS spectra of Fe(II) SCO complexes.…”

Guest-triggered “Soma–Iwamoto-type” penetration complex {Fe(4-methoxypyrimidine)2[M(CN)2]2}·Guest (M = Ag, Au)

“…To date, the reported "Hofmann-type" complexes can be divided into two types. The first type is bridged by square planar tetra-coordinated divalent cyanometalate [M(CN) 4 ] 2− (M = Ni, Pd, Pt) [3][4][5][6][7][8][9][10] such as Fe(pz)[M(CN) 4 ]•H 2 O (M = Ni, Pd, Pt), 10 while the other is bridged by linear coordinated monovalent cyanometalate [M(CN) 2 ] − (M = Ag, Au). [11][12][13][14][15][16] The first complex possessing the latter type of structure is [Cd(4,4′-bpy) 2 {Ag (CN) 2 } 2 ], 17 while the second is [Cd( py) 2 {Ag(CN) 2 } 2 ], 18,19 which were both reported by Soma and Iwamoto, and therefore, the latter type of structures are denoted as "Soma-Iwamoto types".…”