Theoretical descriptions of novel silicon analogs of cyclo[18]carbon

Abstract

AbstractThe effects of substituting silicon atoms on the stability, geometrical parameters, and electronic properties of cyclo[18]carbon (C18), C17Si, and nine isomers of C16Si2 (C16Si2(0) to C16Si2(8)) are compared and contrasted at CAM‐B3LYP/6‐311G* level of theory. Among C16Si2 isomers, the trend of stability (based on total and binding energy [Eb]) is C16Si2(8) > C16Si2(4) > C16Si2(2) > C16Si2(7) > C16Si2(6) > C16Si2(5) > C16Si2(3) > C16Si2(1) > C16Si2(0), at B3LYP/6‐311G*, B3LYP/6‐311++G**, WB97XD/6‐311G*, and CAM‐B3LYP/6‐311G* level of theories. Respectively, the highest and lowest band gaps belong to C18 and C17Si, which also have the smallest and largest conductivities. According to the heat of atomization per carbon (ΔHat/C) and heat of formation (ΔHf), the least thermodynamic stable species, C16Si2(0), suffers from the highest inter‐atomic interaction of neighboring silicon atoms (Si‐Si repulsion) and the most thermodynamic stable species, C16Si2(8), that has the furthest silicon atoms from each other. Theoretical analysis indicates that the most chemically reactive isomers are C16Si2(1), (3), and (5), which have high nucleophilicity (N = 2.752, 2.665, and 2.573 eV, respectively) and electrophilicity (ω = 0.126, 0.128, and 0.128 eV, respectively). The Si substitution increases the polarizability and activity of rings to interact with their surrounding polar species.