Chem. Eur. J.

Conversions of Osmabenzyne and Isoosmabenzene

We report herein the first example of the conversion of metallabenzyne II and isometallabenzene III. The osmium hydride vinylidene complex 1 reacts with HCCCH(OEt)2 to give osmabenzyne 3 via isoosmabenzene 2. Compound 3 exhibits high thermal stability in air. Nonetheless, nucleophilic attack at 3 provides isoosmabenzenes 4 a and 4 b, or opens the ring to produce 5 a and 5 b.

Silicon-Containing Formal 4 pi-Electron Four-Membered Ring Systems: Antiaromatic, Aromatic, or Nonaromatic?

Density functional theory calculations (B3LYP) have been carried out to investigate the 4π-electron systems of 2,4-disila-1,3-diphosphacyclobutadiene (compound 1) and the tetrasilacyclobutadiene dication (compound 2). The calculated nucleus-independent chemical shift (NICS) values for these two compounds are negative, which indicates that the core rings of compounds 1 and 2 have a certain amount of aromaticity.