A readily accessible CH anion transfer reagent for the preparation of a molybdenum methylidyne complex

TL;DR

Scientists created a new and efficient reagent to produce a molybdenum methylidyne complex using a CH anion, with a faster and clearer reaction pathway than previous methods.

Contribution

A new, readily accessible CH anion transfer reagent and a faster pathway for forming a molybdenum methylidyne complex are introduced.

Findings

The new reagent delivers a CH anion to form a molybdenum methylidyne complex rapidly and quantitatively.

The reaction proceeds via a stepwise pathway involving a radical intermediate, as shown by experimental and computational studies.

The bond cleavage rate is over six orders of magnitude faster than the previous method using a metal cyclopropyl complex.

Abstract

A route to a readily accessible source of an anionic methylidyne group (CH−) was developed via lithium–halogen exchange of 11-iodo-9,10-dihydro-9,10-methanoanthracene (MA-I). Upon reaction of this alkyllithium precursor with the complex (TMS-TREN)MoCl as a test platform, the methylidyne complex (TMS-TREN)Mo

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CH is quantitatively and rapidly delivered with concomitant loss of anthracene. The kinetics and mechanisms of this reaction are investigated experimentally and computationally and suggest the intermediacy of a metal cycloalkyl complex that releases anthracene through a stepwise pathway via a radical intermediate; the rate of this bond cleavage reaction is more than six orders of magnitude faster than the previously reported route to this complex via ethylene loss from a metal cyclopropyl complex.

A new reagent for delivering a “CH” anion is developed and demonstrated in the preparation of a molybdenum methylidyne complex. Computational and kinetic studies suggest a stepwise pathway via a radical intermediate.

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