Synthesis of Hypervalent Pentavalent Carbon and Boron Compounds

Various carbon and boron compounds bearing a 1, 8-disubstituted anthracene skeleton were synthesized and characterized by X-ray analysis. They showed three types of structures based on the kinds of substituents. The first one is symmetrical and is a loose pentacoordinate structure, which has the sp2 carbon or boron atom and the two weak apical interactions. The next one is an unsymmetrical tetracoordinate structure, which has the sp3 central atom. The last one is symmetrical and is a tight pentacoordinate structure, which resulted from the special feature of the fluorine substituents on the boron. The existence of hypervalent interaction was proved by the Atoms In Molecules Theory, experimental electron distribution analysis and a comparison among the structures of tight and loose pentacoordinate species. The synthesis and structures of hypervalent carbon compounds with a 2, 6-bis (aryloxymethyl) benzene ligand are also discussed.