Theoretical design of the biradical character in 1,3-diphosphacyclobutanediyl and homologous structures†‡
Abstract
The electronic nature of 1,3-diphosphacyclobutane-2,4-diyl is explored with wavefunction based and density functional methods. According to MCSCF calculations the singlet state of the title compound is a biradicaloid with closed shell character, the number of unpaired electrons, assigned upon the analysis of the natural orbitals, is close to one. The participation of closed shell contributions in the overall wavefunction arises from a strong mixing of canonical structures, which emphasizes (a) the