Theoretical study on a family of organic molecules with planar tetracoordinate carbon

Based on the most stable structure of C 3 B 2 H 4 and its substitution of H with -Cl, -CH 2 OH, -CHOH, -C O and -COOH groups, a series of derivatives containing the planar tetracoordinate carbon (ptC) atoms as well as crown ether-like compounds from the assembling of C 3 B 2 H 4 units have been constructed. At the B3LYP/6-311++G** and MP2/6-31G** levels of theory, these ptC compounds were predicted to be stable and they generally have large HOMO–LUMO gaps. The IR characteristic bands arising from the symmetrical and asymmetrical stretching vibrations of C–ptC, the stretching vibrations of C–B and B–H as well as the breath vibration of the two three-membered rings of C 3 B 2 appear at 1000, 1250, 1600, 2800, and 1700 cm −1 , respectively. Calculations also show that these ptC molecules have strong aromaticities and the ptC atom obeys the octal rule. Furthermore, the derivatives C 3 B 2 H 2 (COOH) 2 and tetra-C 3 B 2 H 2 -16-crown-4 can serve as the chelate ligands and form stable complexes with uranyl.