Quantum Chemical Exploration of Intermolecular Reactions of Acetylene

Quantum chemical explorations of potential energy surfaces showed that acetylene produces various products starting from molecular arrays in short distances of 1.3–2.5 Å. Arrays of (C 2 H 2 ) 2 gave cyclobutadiene, tetrahedrane, and acetylene dimers. Arrays of (C 2 H 2 ) 3 gave benzene, prismane, benzvalene, Dewar benzene, and acetylene trimers. Arrays of (C 2 H 2 ) 4 gave cubane, cyclooctatetranene, and acetylene tetramers. Different forms of initial arrays yielded different sets of products; a parallel array of two monomers gave cyclobutadiene, whereas a cross array gave tetrahedrane. Initial molecular arrays with unusually close contacts were estimated to require local forces of 1–9 × 10 −8  N. © 2019 Wiley Periodicals, Inc.