Spin–spin interaction between phenoxyl radicals through σ–π system

Modulation of Open‐shell Characters of Amine‐inserted Diphenoquinones via Structural Modification

“…The structure and closed‐shell nature of 1 demonstrated that the extended quinoid structure could be maintained even after the insertion of the three‐coordinate nitrogen atom to the diphenoquinone similar to the insertion of benzene, thiophene, and thieno[3,2‐ b ]thiophene . Although extended para ‐quinones with heteroatom‐insertion like 1 are of interest from the viewpoints of structural and physical organic chemistry, there have been few examples of such molecules due to their instability leading to removal of the heteroatom . In this context, it is interesting to explore the structure‐property relationships of amine‐inserted extended para ‐quinones having exceptional stability.…”

“…[5À8] For this reason, 1 couldb er egardeda sa ne xtended para-quinone having an amino nitrogen inserted in the middle of a tert-butyl (tBu) protected diphenoquinone (Scheme1). [13,14] In this context, it is interesting to explore the structure-property relationships of amine-inserted extended para-quinones havinge xceptional stability.I nt his work, we aimed to modulate the strength of antiferromagnetics pin-spin coupling in 1 ande nhancet he open-shell character by modifying systematically the structure of 1.A safirst step, we designed ad erivative of 1 having four phenylg roups instead of tBu groups (2a). [12] Although extended para-quinones with heteroatom-insertionl ike 1 are of interest from the viewpoints of structurala nd physical organic chemistry,t here have been few examples of such molecules due to their instability leadingt or emoval of the heteroatom.…”

“…[12] Although extended para-quinones with heteroatom-insertionl ike 1 are of interest from the viewpoints of structurala nd physical organic chemistry,t here have been few examples of such molecules due to their instability leadingt or emoval of the heteroatom. [13,14] In this context, it is interesting to explore the structure-property relationships of amine-inserted extended para-quinones havinge xceptional stability.I nt his work, we aimed to modulate the strength of antiferromagnetics pin-spin coupling in 1 ande nhancet he open-shell character by modifying systematically the structure of 1.A safirst step, we designed ad erivative of 1 having four phenylg roups instead of tBu groups (2a). [15,16] In 2a,t he open-shell state could be stabilized compared with that of 1 because of the further delocalization of the radical spins on the outer four phenyl groups ( Figure S24), and therefore the energy gap between the closed-shell singlet and triplet states (DE CS-T )c ould be reduced.…”

Preparation and Properties of Perarylated 3,4-Disila-1,5-hexadienes. A Fluorescent Disilane Accommodated in the Crystal Lattice

“…On the other hand, the Si–Si and CC bonds of 4b , c , e , f are twisted with larger torsion angles (30.9(3)–49.2(3)°), as shown in Figure g. The crystal structures of diaryldisilanes prefer a perpendicular conformation of the Si–Si bond to the attached aromatic rings, which favors overlap of the Si–Si σ orbitals and CC π orbitals (σ–π conjugation) . The Si–Si bond distance of 4a (2.402(3) Å) is longer than those of 4b , c , e , f (2.362(2)–2.395(1) Å) regardless of the electronic effects of the substituents and is longer than normal Si–Si bond distances (2.33–2.37 Å) .…”

Electron spin resonance (some chemical applications)

“…When the bridging diphenylenesilanylene unit was arranged such that the two phenoxyl moieties were substituted respectively at a meta and a para position, this led to either a triplet ground state or to the degeneracy of the triplet and singlet states; in contrast, when both phenoxyl groups were para-substituted, a singlet ground state was observed instead. 85…”