Structural characterization and electrochemical behavior of oxovanadium(V) complexes with N-salicylidene hydrazides

Mixed‐Ligand Oxidovanadium(V) Complexes with N′‐Salicylidenehydrazides: Synthesis, Structure, and 51V Solid‐State MAS NMR Investigation

“…These electrochemical features are basically similar to what has been observed for mixedligand oxidovanadium(V) complexes based on non-functionalized NЈ-salicylidenehydrazide ligands, [35] although the two half-wave potentials for the latter cases are somewhat shifted to more negative values (U 1 1/2 = -0.460 V and U 2 1/2 = -2.453 V). The frequency dependence of the peak current of the reduction steps related to Equation (1) and (2) as well as that of the accompanying pre-wave of the second step is depicted in Figure 2.…”

“…Nevertheless, the CSA tensor is very sensitive towards changes in the local environment of vanadium(V) nuclei and in the presence of an oxido group dominated by the V=O bond. [35] All other reagents were used as received without further purification.…”

“…[35] Somewhat larger effects are observed for the hydroxyl-functionalized side chains with an observed range of about 40 ppm (see Table 1). Interestingly, the two complexes [VO(salhyhp)(hq)] and [VO(salhyhh)(hq)] exhibit a value of δ = -408 ppm about the same anisotropy, whereas for the complex with the shortest alkyl spacer [VO(salhyhb)(hq)] a value of δ = -449 ppm is observed.…”

“…[35] ) are very small (bond lengths Ͻ 2 pm; bond angles Ͻ 5°). In addition, for all complexes large discrepancies have been observed between the isotropic chemical shifts in the solid state and in solution, which ranges from about 10 to 40 ppm.…”

A journey into the electrochemistry of vanadium compounds

“…Ten years later, Plass obtained VO 3+ complexes, prepared coordinating N-acyloylhydrazones (butanoyl, pentanoyl, and hexanoyl) from salicyl aldehyde and 8-hydroxyquinoline [176]. Electrochemical investigations showed quasi-reversible square wave voltammograms with two one-electron reduction steps for all complexes, the first one relative to V(V) → V(IV), while the second involved the ligand 8-hydroxyquinoline; electrochemistry was discussed in detail only for VO(salhyp)(quinol) ( Table 5, entry 66), but all have the same potentials, within ±2 mV.…”