The chemistry of molybdenum and tungsten. Part 7. Oxomolybdenum(V) and oxotungsten(V) complexes of neutral aromatic Schiff-base ligands

Synthesis, Structure, and Bonding of d3 Molybdenum–Oxo Complexes

“…Magnetic moments of similar magnitude have been observed for (d xy ) 1 molybdenum-oxo compounds (1.5-1.7 m B ). [14,16] TheEPR spectrum of 5 ( Figure S17) is consistent with the low-spin configuration (g eff = 1.89), as are DFT calculations,w hich predict that the 2 [(d xy ) 2 (p a *(MoO)) 1 ] (Table S9). Thec alculated spin density of the doublet radical indicates that it is localized on the MoO unit (Mo,7 2%;O ,2 7%; Figure S29), as expected for the observed electron configuration.…”

“…Electrochemical Studies. Thee lectrochemistry of the d 2 compounds 1[PF 6 ], [12] 2[BPh 4 ], [13] 3[BPh 4 ], [13] 4[PF 6 ], [14] 5-[BF 4 ], [15] and 6[BPh 4 ] [16] was studied by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in order to assess the stability and possible synthetic accessibility of their d 3 redox congeners.T he CV and DPV data ( Table 1, Figures S21-S26) exhibit an oxidation assigned to the M IV/V couple and ar eduction assigned to the M IV/III couple.T he electrochemical reversibility of the reductions of these ions is af unction of the extent to which their oxo ligands are sterically shielded by the phosphine substituents.The data for 5[BF 4 ]( Figure 3A)a re representative of those for compounds with phosphine Rgroups that shield their oxo ligands (3 + -6 + ). Fort hese ions,t he reductions are reversible: Randles-Sevcik plots of the scan-rate dependence of the anodic and cathodic peak currents are linear and, for agiven compound, possess slopes that are equal in magnitude but opposite in sign.…”

Synthesis and antioxidant activities of Schiff bases and their complexes: a review

“…The numerous molybdenum(VI) Schiff base complexes have been extensively investigated for over twenty years. Owing to their importance in the domains of stereochemistry and structural and analytical chemistry and as model systems for the interaction of organic substrates with catalytic oxide surfaces, some of them are also interesting due to their ability to oxidize thiols, hydrazines, polyketones and tertiary phosphines . Their oxygen atom transfer properties play a significant role in investigating the functioning mechanism of molybdenum oxotransferase .…”

Synthesis, characterization and catalytic activity of dioxidomolybdenum(VI) complexes of tribasic pentadentate ligands

“…The significant enzymatic role of molybdenum in biochemical reactions, especially in the oxidation of aldehydes, purines and sulfides [1,2], has attracted researchers to use high-valent molybdenum complexes with a cis-[Mo VI O 2 ] functionality as biomimetic catalysts in the oxygenation of organic compounds [3][4][5]. The oxygen atom transfer properties of these complexes play a significant role in investigating the functioning mechanism of molybdenum transferase enzymes, which also consist of a cis-[Mo VI O 2 ] moiety as the active site [6][7][8][9][10][11][12].…”