The valence state of ionic molecular solids composed of biferrocene derivatives (D) and tetracyanoquinodimethane (TCNQ) derivatives (A), either monovalent ([D] + [A2] −) or divalent ([D] 2+ [A2] 2−), can be controlled by changing the redox potentials and molecular volumes of the components.
The crystal architecture, magnetic properties, and thermodynamic properties of [n-butylferrocene][Ni(mnt)2] (1), [tert-butylferrocene][Ni(mnt)2] (2), [1,1'-diethylferrocene][Ni(mnt)2] (3), and [1,1'-diisopropylferrocene][Ni(mnt)2] (4) were investigated (mnt=maleonitriledithiolate). These complexes exhibit a unique supramolecular structure in which the ferrocenium cations constitute honeycomb-like assembled structures surrounding columns of the anions. For 1, the cations form a dimer through a very short intermolecular ferrocene-ferrocene distance of 3.28 A, which mediates an antiferromagnetic interaction with a singlet-triplet energy gap of 5 K. First-order phase transitions occur in 1-3 at 364, 361, and 350 K, respectively, accompanied by thermal hysteresis.
Preparation and structures of biferrocenes with alicyclic substituents: Order-disorder of substituents in the crystal structures of cyclohexenylbiferrocene and its charge-transfer salt
Decamethyl-and octamethyl-ferrocenium salts of F n TCNQ (n = 1, 2) were prepared and their crystal structures characterized. The 2,5-F 2 TCNQ salts [Fe(C 5 Me 5) 2 ](2,5-F 2 TCNQ) (1) and [Fe(C 5 Me 4 H) 2 ](2,5-F 2 TCNQ) (2) exhibit one-dimensional ...[D] + [A] − [D] + [A] − ... mixed-stack structures, while the salts with polar acceptors [Fe(C 5 Me 5) 2 ][A] (A = F 1 TCNQ (3), 2,3-F 2 TCNQ (4), 2,6-F 2 TCNQ (5)) and [Fe(C 5 Me 4 H) 2 ][A] (A = 2,3-F 2 TCNQ (6), 2,6-F 2 TCNQ (7)) consist of [D] + [A 2 ] 2− [D] + units involving a diamagnetic dimer of the acceptors. These salts are isomorphous to the corresponding TCNQ salts. 1 and 2 exhibit small ferromagnetic interactions at low temperatures. 1 undergoes an antiferromagnetic phase transition at T N = 3.9 K, which is higher than T N = 2.1 K of the metamagnetic polymorph of [Fe(C 5 Me 5) 2 ](TCNQ).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.