In the VVO(ONO)(ON) and VIVO(ONO)(NN) families H2ONO = N-(2-hydroxyphenyl)salicylaldimine (H2amp), 2,2'-dihydroxyazobenzene (H2azp), N-(2-carboxyphenyl)salicylaldimine (H2amc), or 2-hydroxy-2'-carboxy-5-methylazobenzene (H2azc); ON = 8-quinolinol (Hhq); NN = 2,2'-bipyridine (bpy) or 1,10-phenanthroline (phen). Reaction of VO(acac)2 with a mixture of H2amp and bpy or Hhq in MeOH affords VIVO(amp)bpy) or VVO(amp)(hq) (oxidant is aerial O). Complexes of azp2- and amc2- are similarly made, while those of azc2- are synthesized from preformed VO(azc).3H2O. In both VO(azc)(hq).2MeOH and VO(azc)(bpy) the V(azc) and V(bidentate) fragments are resp. nonplanar and planar. The V-O distances within V(azc) are shorter in the former complex. Crystals of VO(azc)(hq).2MeOH are triclinic, space group P1̅, a 8.104(3), b 12.217(4), c 12.573(5) Å, a 100.62(3), β 92.26(3), γ 105.81(3)°, Z = 2, R = 0.0669, Rw = 0.0669. Crystals of VO(azc)(bpy) are monoclinic, space group P21/c, a 9.848(4), b 18.169(6), c 12.936(4) Å, β 111.78(3)°, Z = 4, R = 0.0625, Rw = 0.0639. In VO(ONO)(NN) and electrogenerated VO(ONO)(ON)- the 51V EPR hyperfine constants (Aav) are slightly larger in the amc2- and azc2- (∼102 G) than in the amp2- and azp2- (∼99 G) complexes. The more nucleophilic phenolato function delocalizes electron d. better. The VO3+-VO2+ E1/2 values shift considerably to more neg. values when neutral NN is replaced by anionic ON, which also provides better VO3+ binding via phenolato oxygen. For a given bidentate ligand E1/2 increases in the order amp2- < azp2- < amc2- < azc2- and correlates linearly with ∑pKa, which represents the sum of pKa's of the variable N and O functions.