LAUSR

Proposing new valence electron counting rules and new structural motifs are both very important in chemistry. In this work, we unexpectedly found that by introducing a π-type skeleton YCCY (Y = Al/Ga/In/Tl), a total of sixteen novel planar tetracoordinate heavier group 14 species, that is, ptM (M = Si/Ge/Sn/Pb) in neutral, can be designed as global minima. The underlying bonding situation contrasts sharply both with the well-known 18ve-ptC and the limited 18ve-ptM, for which there is little multiple bonding character within the skeleton. The fact that each YCCY (Y = Al/Ga/In/Tl) can stabilize all heavier group 14 atoms in a planar tetracoordinate fashion strongly demonstrates the universality of such a π-type skeleton. The present work firmly demonstrates that introducing the π-type ligand skeleton can effectively enrich the planar tetracoordinate chemistry with the heavier group atoms.