Abstract
Advances in the molecular variety and the elucidation of the physical properties of 1,10-phenanthroline annulated with 1,2,5-thiadiazole and 1,2,5-thiadiazole 1,1-dioxide moieties have been achieved, and are described herein. A 1,2,5-thiadiazole compound, [1,2,5]thiadiazolo[3,4-f][1,10]phenanthroline (tdap), was used as a ligand to create multidimensional network structures based on S•••S and S•••N intermolecular interactions. A 1,2,5-thiadiazole 1,1-dioxide compound, [1,2,5] thiadiazolo[3,4-f][1,10]phenanthroline, 1,1-dioxide (tdapO2), was designed to create a stable radical anion, as well as good network structures. Single crystal X-ray structure analyses revealed that transition metal complexes of tdap, and radical anion salts of tdapO2 formed multidimensional network structures, as expected. Two kinds of tdap iron complexes, namely [Fe(tdap)2(NCS)2] and [Fe(tdap)2(NCS)2]•MeCN exhibited spin crossover transitions, and their transition temperatures showed a difference of 150 K, despite their similar molecular structures. Magnetic measurements for the tdapO2 radical anion salts revealed that the magnetic coupling constants between neighboring radical species vary from strongly antiferromagnetic (J = −320 K) to ferromagnetic (J = 24 K), reflecting the differences in their π overlap motifs.
Highlights
As a result of the major efforts to enhance the dimensionality of intermolecular interactions, heterocyclic sulfur nitrogen (SN) compounds, which consist of nitrogen atoms and sulfur atoms, have arisen, and their solid-state properties have been investigated in relation to their crystal structures
The temperature dependences of χp of these radical anion salts were calculated with diamagnetic susceptibilities that were obtained as fitting parameters of the Bonner-Fisher model and Bleaney-Boweres model, respectively
The effect of the intermolecular interaction on the physical properties was shown in the spin-crossover complex by the shift in their transition temperatures. [Fe(tdap)2(NCS)2]MeCN and
Summary
The electrical and magnetic properties of molecular crystals have been studied extensively, and various molecule-based conductors [1,2,3,4,5,6,7], superconductors [6,8,9,10,11,12,13,14], and magnetic materials [15,16,17,18,19,20,21,22,23,24,25,26,27]. The synthesis of a closed-shell SN compound, [1,2,5]thiadiazolo[3,4-f][1,10]phenanthroline (tdap, Scheme 1a), was reported in 2006 [34] Using this compound as a ligand, the intermolecular interactions and electron spins which are the remarkable features of SN radicals can be separated into the 1,2,5-thiadiazole moieties and the transition metal ions, respectively. Radical anion salts of [1,2,5]thiadiazolo[3,4-f][1,10]phenanthroline 1,1-dioxide (tdapO2, Scheme 1b) were reported and shown to be stable under ambient conditions and to have multidimensional network crystal structures [47,48].
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