Synthesis of protonated carboxylato and trifluoromethanesulfonato derivatives of vanadium(II) by redox reactions on bis(mesitylene)vanadium(0)

Bis(mesitylene)vanadium(0), V(mes) 2 , underwent a two-electron redox process in heptane with CF 3 SO 3 H affording the vanadium(II) derivative [V(CF 3 SO 3 ) 2 (CF 3 SO 3 H)], an example of a co-ordination compound containing both the acid and its conjugated base in its composition. The vanadium(0) complex and CF 3 CO 2 H gave a product resulting from a one-electron transfer process, namely [V(mes) 2 ][CF 3 CO 2 ]. This compound, which dissolves unchanged in neat CF 3 CO 2 H–(CF 3 CO) 2 O, evolves to the vanadium(II) derivative [H(thf) n ][V(CF 3 CO 2 ) 3 ] (thf = tetrahydrofuran) by addition of tetrahydrofuran. Deprotonation of the vanadium(II) complexes occurs in the presence of thf or heterocyclic nitrogen bases to form the ionic derivatives [HB][VA 3 ], B = thf or a heterocyclic nitrogen base; A = CF 3 SO 3 or CF 3 CO 2 . The trifluoroacetato derivative [H(thf) n ][V(CF 3 CO 2 ) 3 ] undergoes methylation with CH 2 N 2 to the vanadium(II) ester adduct [V(CF 3 CO 2 ) 2 (CF 3 CO 2 CH 3 )], and is oxidized to the vanadium(III) trifluoroacetato derivatives [V(CF 3 CO 2 ) 3 ] and [V(CF 3 CO 2 ) 2 C 14 H 8 O 2 ] by benzoyl peroxide (or dioxygen) and 9,10-phenanthrenedione, respectively.