Abstract
In the elucidation of complex multistep reactions, it is easy to
overlook significant mechanistic hypotheses. Hence, the use of
computer programs to search for mechanisms is attractive, but these
programs must respect the prior knowledge held by the investigator.
Virtually all knowledge-based programs accommodate prior knowledge of
either what can or what cannot happen, but there are advantages in
exploiting both types of knowledge simultaneously. We report a novel
alliance of two programs that enables these advantages, and which
represents an advance in the capabilities of computational chemistry,
as illustrated here on the complex synthesis of acrylic acid from
acetylene, CO, and water catalyzed by palladium complexes. The
pathways reported by the programs were categorized as hydride,
hydroxycarbonyl (alcoholate-like), and metallocyclic, the mechanistic
types that are known from publications on hydrocarboxylation and
hydrocarbalkoxylation of unsaturated molecules in solutions of
transition metal complexes. Many specific pathways were not before
considered in the absence of computerized searches.
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