Attempts at generating metathesis-active Fe(IV) and Co(IV) complexes via the reactions of (silox)2M(THF)2, [(silox)3M][Na(THF)2] (M = Fe, Co), and related species with propellanes and triphenylboron

Metathetical syntheses of (silox)(2)M(THF)(2) (1-M, Fe, Co), [(silox)3M]Na(THF)(2) (2-M, Fe, Co), and (silox)(3)Fe(THF) (3) are presented, as are X-ray structural studies of 1-Co, 2-Fe, and 2-Co. Exposure of these complexes to 1.1.1propellane (111P, C5H(6)) and 1,3-dehydroadamantane (AdP), which are known progenitors of ROMP-active alkylidenes with ruthenium, failed to elicit similar reactivity. A total of 28 complexes were subjected to 111P in attempts to make Fe(IV) alkylidenes capable of some form of olefin metathesis with no success. At best, catalytic ring-opening to 3-exo-methylene cyclobutylidene was evidenced. The addition of triphenylboron as a Lewis acid failed to aid in metal complex formation of the propellanes, but an unusual rearrangement of AdP was noted. In addition, 2-Fe catalyzed the conversion of 111P to 3-exo-methylene cyclobutylidene, which added twice to Ph3B, affording a structurally characterized product, Ph(kappa-CH=CMeCH2BPh(cC(4)H(4)-1-Ph,3-CH2) (4), which features cyclobutyl-ring-opening, migration, and phenyl migration.

Automated summary

This article presents the metathetical syntheses of a series of complexes and X-ray structural studies of some of them. However, the reactivity of these complexes towards 1.1.1propellane and 1,3-dehydroadamantane did not yield the expected results. The best outcome observed was catalytic ring-opening to 3-exo-methylene cyclobutylidene.