Substituent Effect in the Cation Radicals of Monosubstituted Benzenes.

In 30 monosubstituted benzene cation radicals, studied at the ωB97XD/aug-cc-pVTZ level, the phenyl rings usually adopt a compressed form, but a differently compressed form-equivalent to an elongated one-may coexist. The computational and literature ionization potentials are well correlated. The geometrical and magnetic aromaticity, estimated using HOMA and NICS indices, show the systems to be structurally aromatic but magnetically antiaromatic or only weakly aromatic.

Substituent Effect in the First Excited Triplet State of Monosubstituted Benzenes.

The structure of 30 monosubstituted benzenes in the first excited triplet T state was optimized with both unrestricted (U) and restricted open shell (RO) approximations combined with the ωB97XD/aug-cc-pVTZ basis method. The substituents exhibited diverse σ- and π-electron-donating and/or -withdrawing groups. Two different positions of the substituents are observed in the studied compounds in the T state: one distorted from the plane and the other coplanar with a quinoidal ring.

Substituent Effect in the First Excited Singlet State of Monosubstituted Benzenes.

sEDA, pEDA, and cSAR descriptors of the substituent effect were determined for >30 monosubstituted benzenes in the first excited singlet S state at the LC-ωB97XD/aug-cc-pVTZ level. It was found that in the S state, the σ- and π-valence electrons are a bit less and a bit more affected, respectively, than in the S state, but basically, the effect in both states remains the same. In the S and S states, the d(C-X) distances to the substituent's first atom and the ring perimeter correlate with the sEDA and pEDA in the appropriate states, respectively.

On constitutional isomers and tautomers of oxadiazolones and their mono- and disulfur analogues (CHNXY; X, Y = S, O).

The constitutional isomers and tautomers of oxadiazolones, as well as their mono- and disulfur analogues, were calculated at the B3LYP/aug-cc-pVDZ level. Four groups of 30 molecules each were considered: oxadiazolone, oxadiazolthione, thiadiazolone, and thiadiazolthione isomers. The compounds were categorized into six groups according to permutations of three heteroatoms in the five-membered ring.

Role of ultrasonography in diagnosis and differentiation of pleomorphic adenomas: work in progress.

Objective: To estimate the utility of ultrasonography in diagnosis and differentiation of pleomorphic adenomas.

Design: From the group of 88 patients examined by ultrasound, who were referred because of the tumor in the preauricular area, submandibular area, or cheek, pleomorphic adenoma was finally diagnosed in 24 (with multiple recurrent tumors in 2 patients).

Results: Ultrasound was able to differentiate between benign and malignant lesions with 96% accuracy in this study.