1,1'-(p- or m-phenylene)bis(2,4,6-triphenylpyridinyl) diradicals: Ground state in a heteroatom-containing system in relation to the topology rule

Tetrahedron Letters

Volumn 38, Issue 34, 1997, Pages 6007-6010

  Okada, Keiji ^a   Matsumoto, Kouzou ^b   Masaji, Oda ^b   Akiyama, Kimio ^c   Ikegami, Yusaku ^c  

^a Osaka Prefecture University   (Japan)

^b OSAKA UNIVERSITY   (Japan)

^c TOHOKU UNIVERSITY   (Japan)

Author keywords

[No Author keywords available]

Indexed keywords

PHENYLENEDIAMINE DERIVATIVE; PYRIDINE DERIVATIVE; RADICAL;

ARTICLE; DRUG STRUCTURE; DRUG SYNTHESIS; ELECTRON SPIN RESONANCE; IN VITRO STUDY; MOLECULAR DYNAMICS; TEMPERATURE;

EID: 0030837380     PISSN: 00404039     EISSN: None     Source Type: Journal    
DOI: 10.1016/S0040-4039(97)01335-X     Document Type: Article

References (21)

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17. s = ±2 transition was also detected in 4.
18. The diradical 3 and 4 is unstable under aerated conditions but stable under inert atmosphere for long time at room temperature.
19. 2 = ca. 3.8 for the singlet states, ca. 4.8 for the triplet states); Greenberg, M. M.; Blackstock, S. C.; Stone, K. J.; Berson, J. A. J. Am. Chem. Soc., 1989, 111, 3671-3679.
20. 2-carbons linked to the nitrogen atom are in the range between 0.13-0.24 Å.
21. Interestingly, the triplet state of the para diradical 3 and the singlet state of the meta diradical 4 have two distinct dihedral angles, whereas the singlet state of 3 and the triplet state of 4 have nearly equal dihedral angles. Since the triplet (singlet) state has an a spin in one pyridinyl ring and an α (β) spin in the opposite ring, the triplet state of 3 (the singlet state of 4) would receive the electronic repulsion between the α (β) spin on the N1 atom and the α (β) spin on the N1-attached phenylene carbon, where the spin is induced by the α spin on the N1′ atom through the dynamic spin polarization as shown in D (p-phenylene triplet) and E (m-phenylene singlet). Such electronic repulsion must be released by increasing the dihedral angle in one of the pyridinyl rings. equation represented