  Two-dimensional (2D) materials have wide applications towards electronic
devices, energy storages, and catalysis, et al. So far, most of the pure
element 2D materials are composed of group IIIA,IVA, and VA elements. Beyond
the scope, the orbit hybrid configuration becomes a key fact to influence 2D
structure stably. Here we show a sp2d3 hybridization in the outmost electrons
with O-shell for Iodine and P-shell for astatine element, builds up triangle
configuration (beta-type) to form 2D structures beta-iodiene and
beta-astatiene. Each atom is connected by pi bonds, and surrounded by 6 atoms.
The pi bonds become possible, and band gap approaches zero because of
interaction of unpaired single electron to each atom, depending on reducing
bond length. By applying compression strain or spin orbit coupling (SOC), the
Dirac points or topological nontrivial points can be available in the
beta-iodiene and beta-astatiene. Our discovery has paved a new way to
construction of 2D materials.
