Planar hypercoordinate carbon

In this chapter, we aim to deliver a brief review of the planar hypercoordinate carbon compounds. The conventional idea of carbon centers in organic molecules is that they have a maximum of four coordination numbers with tetrahedral geometries, i.e., the attached atoms or groups occupy four vertices of a tetrahedron. But the planar tetracoordinate carbon (ptC) molecules violate this conventional tetrahedral concept of tetracoordinate carbons. In the case of planar geometry with carbons, the maximum coordination is usually three. So, when four or more atoms or groups are attached to a planar carbon in the same plane, the system is considered to be a planar hyper coordination.