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

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[triple bond, length as m-dash]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.