A vanadium-promoted C-N bond cleavage

A C-N bond in one arm of the mixed-valence V^III-V^IV complex bpbp(VOCl₂)(VCl₂), bpbpH = 2,6-bis((N,N-bis-(2-picolyl)amino)methyl)-4-tertbutylphenol, is cleaved in wet acetonitrile solution to give bpa(VOCl₂), bpa = bis(2-methypyridyl)amine, and 2-((N,N-bis-(2-picolyl)amino)methyl)-6-hydroxymethyl-4-tertbutylphenol. The reaction corresponds overall to hydrolysis of a tertiary amine to form a secondary amine and a primary alcohol. The structure of bpa(VOCl₂) was established by X-ray diffraction while 2-((N,N-bis-(2-picolyl)amino)methyl)-6-hydroxymethyl-4-tertbutylphenol was detected by ESI mass spectrometry. The phenol oxygen atom in bpbp(VOCl₂)(VCl₂) is proposed to be non-bridging and this asymmetry is likely to be important for the C-N bond cleavage reaction. A related asymmetrical V^IV complex, bpbpH(VO)(H₂O)](ClO₄)₂ ·  H₂O, containing bpbp⁻ bound to only one metal ion, has also been characterized by X-ray diffraction. In slightly more basic solution, bpbp(VOCl₂)(VCl₂) is oxidized to the V^IV-V^IV complex bpbp(VOCl)₂]⁺ and C-N bond cleavage is suppressed.