The reaction of aluminum atoms with methane

Abstract

. Can. J. Chem. 68, 633 (1990). Ab initio SCF and CISD calculations with split valence and larger basis sets have been carried out for several possible reactions of ground state ( 2~) aluminum atoms with methane. In particular, the barriers to insertion of A1 into a CH bond to give a CH3AIH intermediate and the abstraction of a hydrogen by A1 to give AIH and CH3 have been studied. At the SCF level, transition state structures have been located and verified by vibrational analyses. In addition, intrinsic reaction coordinates (IRC) have been followed from the transition state geometries down to reactants and to products. Calculated vibrational frequencies and lowest excitation energy for the CH3AlH intermediate are in good agreement with matrix isolation experimental results. As anticipated on the basis of MO natural correlation symmetry arguments, the energy barrier to the insertion reaction is high (-50 kcal rnol-' at the CI level). The energy requirement for the abstraction reaction is similar. A1 + CH4 + HAlCH3 Insertion A1 + CH4 + HA1 + CH3 Abstraction

Electronic Spectroscopy of the Al−CH4/CD4Complex

“…As with the previously studied Al−H 2 complex, chemical reaction within the Al−CH 4 complex to yield electronically excited AlH(A 1 Π) products is energetically allowed. An additional chemical reaction pathway to form AlCH 3 products is possible for the Al−CH 4 complex . Unfortunately, fluorescence from electronically excited AlCH 3 has not, to our knowledge, been observed, although the laser spectroscopic detection of AlCH 3 by resonance-enhanced multiphoton ionization has been reported .…”

“…The possible reaction pathways in this system have been investigated by quantum mechanical theoretical methods. 3 It was found that the lowest-energy CH 3 AlH product can be reached from the reaction of ground-state atoms with methane through a high-barrier insertion process.…”

“…The reaction between these species within a cryogenic matrix has been studied with various techniques, including UV electronic, IR vibrational absorption, and EPR spectroscopies. , A photoreversible reaction, leading to the formation of CH 3 AlH through an insertion mechanism, was found. The possible reaction pathways in this system have been investigated by quantum mechanical theoretical methods . It was found that the lowest-energy CH 3 AlH product can be reached from the reaction of ground-state atoms with methane through a high-barrier insertion process.…”

Evidence for Higher Reactivity of B2. Theoretical Studies of Insertions of B2 and B into Methane and Water

“…The reaction of bare atoms/clusters with compounds has been a very active field of research. As an important class of reactions, the insertion of bare atoms into molecules such as CH 4 , CH 3 -Hal, NH 3 , H 2 O, C 2 H 2 , and C 2 H 4 has interested scientists for many years. − However, there has been less attention paid to the insertion of atom dimers/clusters, and there is little knowledge about the reactivities of atom dimers/clusters vs atoms. To our knowledge, although several experimental and theoretical studies 2,11,12 have indirectly shown that some atom dimers/clusters are more reactive than bare atoms, no direct and detailed experimental and theoretical evidence to prove it has been reported.…”

Laser-Induced Fluorescence and Mass Spectrometric Studies of the Cu + HCl Reaction over a Wide Temperature Range. Formation of HCuCl

“…There appears to have been no previous observations of HCuCl. However, there have been numerous experimental, − and theoretical − examples of metal atoms inserting into covalent bonds.…”