Unique molecular distortion in the 2,4,6-tri-t-butylphenyl group

Ito, Shigekazu; Miyake, Hideaki; Yoshifuji, Masaaki

doi:10.3998/ark.5550190.0013.202

Cited by 1 publication

(1 citation statement)

References 6 publications

(6 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The dihedral angle between the Mes* aromatic ring and the biradical skeleton of τ = 69.1° indicates a small contribution from the conjugation effect. The C ipso –C ortho and C ortho – t Bu lengths in the Mes* moiety indicate a distortion corresponding to a boat conformation, probably arising from the steric hindrance. The X-ray structure of 7 is almost identical to the DFT-calculated structure [M06-2X/6-31G(d)]…”

Section: Results and Discussionmentioning

confidence: 99%

Direct Arylations for Study of the Air-Stable P-Heterocyclic Biradical: From Wide Electronic Tuning to Characterization of the Localized Radicalic Electrons

et al. 2013

Self Cite

View full text Add to dashboard Cite

We have developed methods for installing aryl substituents directly on the phosphino groups of the 1,3-diphosphacyclobutane-2,4-diyl system. The aryl substituents tuned the electronic and structural characteristics of the biradical unit both in solution and in the solid state. 1-tert-butyl-2,4-bis(2,4,6-tri-tert-butylphenyl)-1,3-diphosphacyclobuten-4-yl anion, prepared from phosphaalkyne (Mes*C≡P; Mes* = 2,4,6-tBu3C6H2) and t-butyllithium, was allowed to react with an electron-deficient N-heterocyclic reagent. The corresponding N-heteroaryl-substituted P-heterocyclic biradicals were produced via SNAr reactions. Biradicals bearing perfluorinated pyridyl substituents exhibited photoabsorption properties comparable to those of previously reported derivatives because the highest occupied and lowest unoccupied molecular orbit levels were reduced by a similar amount. In contrast, the triazine substituent reduced the band gap of the biradical unit, and the large red shift in the visible absorption and high oxidation potential were further tuned via subsequent SNAr and Negishi coupling reactions. The amino-substituted triazine structure provided a strongly electron-donating biradical chromophore, which produced unique p-type semiconducting behavior even though there was no obvious π-overlap in the crystalline state. The single-electron transfer reaction involving Mes*C≡P, phenyllithium, and iodine afforded 1,3-diphenyl-2,4-bis(2,4,6-tri-tert-butylphenyl)-1,3-diphosphacyclobutane-2,4-diyl via the intermediate P-heterocyclic monoradical. The tetraaryl-substituted symmetric biradical product was used to determine the electron density distribution from the X-ray diffraction data. The data show highly localized radicalic electrons around the skeletal carbon atoms, moderately polarized skeletal P-C bonds in the four-membered ring, and no covalent transannular interaction.

show abstract

Section: Results and Discussionmentioning

confidence: 99%