Quenching of the 3P and 1P states of Mg by acetylene and possible formation of vinylidene. A theoretical ab initio SCF CI study

• Published in: Chemical physics Vol. 143; no. 1; pp. 39 - 45
• Main Authors: Chaquin, Patrick, Sevin, Alain, Papakondylis, Aristotelis
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.05.1990; Elsevier
• Subjects: Atomic and molecular physics; Electronic structure of atoms, molecules and their ions: theory; Exact sciences and technology; Physics; Potential energy surfaces; Acetylenic aliphatic compound; Exciplex; Hydrocarbon; Ab initio method; Electronically excited state; Theoretical study; Sigma complex; Conformational energy map; Acetylene; Magnesium Atoms; Gaussian orbital; SCF method; Polarization function; CI method; Potential surface; CIPSI method; Chemical reactivity; Moller Plesset partition; Organic compounds; Conformation
• ISSN: 0301-0104
• DOI: 10.1016/0301-0104(90)85004-G

Physical and chemical quenching of 3P and 1P states have been studied by theoretical ab initio SCF CI methods. The singlet and the triplet are attractive, yielding C 2v triangular π exiplexes. No secondary minimum corresponding to an open form has been found on the singlet surface, whereas the triplet surface exhibits a very shallow secondary minimum corresponding to a a complex. Physical quenching is expected to be efficient for both states. The initial energy of the singlet system is large enough to induce a hydrogen transposition yielding vinylidene magnesium, which, in turn, can easily undergo a CMg rupture and produce vinylidene. This channel might compete with an insertion reaction of Mg into a CH bond.