On the Mechanism of the Spin-Nonconserving Chemical Reaction O(3P) + HCCH → CH2(ãA1) + CO(X1Σ+). I. Feasibility

Abstract

The mechanism of spin-forbidden reaction O(3P) + HCCH(X1 ) → HCCHO(1,23A) → HCCHO(1A) → CH2(a1A1) + CO(X1 ) is discussed. Portions of the 3A‘‘−1A‘, 3A‘−1A‘, and 3A‘‘−3A‘ surfaces of intersection and the spin−orbit coupling matrix elements are determined. An intermediate complex driven model is proposed. Intersystem crossing is expected to occur over the entire region between the intermediate complex, 3HCCHO, and the transition state for the spin-allowed rearrangement, 3HCCHO → 3H2CCO. The barrier for the reaction arises from the formation of the adduct 3HCCHO and is thus the same as that of the spin-allowed process forming CH2(X3B1).