For example, in 1991, Schleyer and Alexander I. Boldyrev, who is now at Utah State University, designed a set of square-planar carbon compounds, including CSi 2 Al 2.

M. J. Hynes, Patricia F. Brannick, The Rates and Mechanisms of Substitution of Square-Planar Complexes of Ni (II), Pd (II), AND Pt (II) Containing Bidentate Sulphur Ligands in Water and Methanol, ...

Several examples of square-planar carbon compounds exist, but boron has so far only been forced into three-coordinate T-shaped planar geometries.