Steric C–N bond activation on the dimeric macrocycle [{P(μ-NR)}2(μ-NR)]2

Abstract

Dimeric cyclophosphazanes [{P(μ-NR)}₂(μ-NR)]₂ [R = ^tBu ( 1) and ⁱPr ( 3)] were oxidized with elemental selenium. During these reactions an unexpected C–N bond cleavage and N–H bond formation occurred. Compound 1 produced P₄(μ-N^tBu)₃(μ-NH)₃Se₄ ( 2) where three ^tBu groups were lost in the form of isobutylene. In contrast, during the oxidation of the less sterically hindered 3, the resulting product, P₄(μ-NⁱPr)₅(μ-NH)Se₄ ( 4), showed only one substituent loss. Theoretical studies confirmed the steric nature of the driving force underlying the different outcomes.