Chemists synthesize 'flat' silicon compounds

Chemists have synthesized extremely unusual compounds. Their central building block is a silicon atom. Different from usual, however, is the arrangement of the four bonding partners of the atom, which are not in the form of a tetrahedron around it, but flat like a trapezoid. This arrangement is usually energetically extremely unfavorable, yet the molecules are very stable.

source https://www.sciencedaily.com/releases/2020/12/201222141530.htm