Simultaneous Occurrence of Quadruple Lewis Acid-Base Interactions between Selenium Atoms in Selenocarbonyl Dimers

High¿level quantum chemical calculations are performed to investigate C=Se¿¿¿Se=C interactions. Bounded structures are found with binding energies between ¿4 and ¿7¿kJ¿mol¿1. An energy decomposition analysis shows that dispersion is the more attractive term, and in all cases save one, the electrostatic interaction is attractive despite each selenium atom having a positive ¿¿hole at the extension of the C=Se bond. The topological analysis of the molecular electrostatic potential and L(r)=¿¿2¿(r) function, and natural bond orbital analysis reveal that these particular Se¿¿¿Se contacts can be considered to be quadruple Lewis acid¿base interactions.G.J.B., D.J.R.D., and N.M.P. acknowledge SEGCYT-UNNE and CONICET for financial support. I.A. thanks the financial support from the Spanish Ministerio de Econom&a y Competitividad (Project No. CTQ2015-63997-C2-2-P) and Comunidad Autónoma de Madrid (Project FOTOCARBON, ref. S2013/MIT-2841). The authors also acknowledge the use of CPUs from the CECONEA. N.M.P. is a career research of CONICET, Argentina.Peer Reviewe