Influence of ring size on the strength of carbon bonding complexes between anions and perfluorocycloalkanes.

In this paper we combine high level theoretical calculations (RI-MP2/def2-TZVP) with Cambridge Structural Database (CSD) analysis to demonstrate the importance of carbon bonding in cyclobutane rings. The higher ability of four-membered rings to interact with electron rich molecules is rationalized using several computational tools, including molecular electrostatic potential surfaces, energetic and geometric features of the complexes and "atoms in molecules" analysis. We have found that the solid state architectures of several X-ray structures, retrieved from the CSD searches, strongly support the theoretical calculations. In particular, carbon bonding interactions are quite common in nitro-substituted cubanes.