Planar Four‐Coordinate Boron: A Single, Flat Boron Atom as a Ligand for Four Metals

You may now kiss the boride: Four-coordinate boron, carbon, and nitrogen are almost always tetrahedral. The first examples of compounds with near-planar four-coordinate boron atoms have been prepared from trinuclear coordinatively unsaturated borido complexes. The two resultant tetranuclear complexes (see scheme) both feature near-planar four-coordinate boron atoms, with angle sums of 362.4° and 364.6°.