Phenylene Coupling of Methylene Sites. The Spin States of Bis(X-methylene)-p-phenylenes and Bis(chloromethylene)-m-phenylene

摘要

We judge the energetic equence of spin states in substituted methylenes by ab initio multiconfigurational conputations and, where feasible, density functional modeling techniques. The best of these calculations reproduce well-established singlet-triplet gaps in X-C-Y species, in which X can be phenyl and Y can be H, methyl, or chloro. Similar computations on p-phenylene-coupled Y-methylenes and meta-coupled Y-methylenes support the suggestion by Zuev and Sheridan that bis(chloromethylene)-p-phenylene has a singlet diradical ground state.