A vanadium-promoted C–N bond cleavage

A C–N bond in one arm of the mixed-valence VIII–VIV 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 VIV complex, [bpbpH(Vdouble bond; length as m-dashO)(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 VIV–VIV complex [bpbp(VOCl)2]+ and C–N bond cleavage is suppressed.