Electrochemical and Spectroscopic Studies of Molybdenumcatechol Complexes: Models for Molybdoenzymes and Biological Transport

A New Class of Complexes Possessing Cofacially-Oriented, Planar, Metal-Containing Subunits. Synthesis, Characterization, and Reactivity of [(MoO2)2(μ-O)]2+-Linked, Catechol-Functionalized, Tetraazamacrocyclic and Salicylideneamine Complexes

“…The anticipated reaction of (Bu 4 N) 2 [Mo 2 O 7 ] with 2 equiv of 3,5-di- tert- butylcatechol took place to yield 1 in 90% yield (Figure B). Spectroscopic properties of 1 obtained from this latter convenient synthesis were consistent with those reported previously. 14b,c The reaction is quite general and proceeds with carboxylic acids (vide infra) and also with the macrocyclic- and SALPHEN-catechol ligands and metal complexes thereof. The use of (Bu 4 N) 2 [(MoO 3 ) 2 (μ-O)] as a reagent in the low-yield synthesis of (Bu 4 N) 2 [Mo 4 O 10 (C 6 H 2 O 4 ) 2 ] from 2,5-dihydroxy-1,4-benzoquinone has been described previously .…”

“…(Bu 4 N) 2 [Mo 2 O 5 (D t BC) 2 ] (1). The spectroscopy and physical properties of this complex, previously obtained by a different synthetic route, were consistent with those reported. Anal.…”

“…The synthesis of the (Bu 4 N) 2 [Mo 2 O 5 (D t BC) 2 ] ( 1 ) complex previously described involves the reaction of MoO 2 (acac) 2 with 2 equiv of 3,5-di- tert- butylcatechol to afford the dimer [MoO(D t BC) 2 ] 2 . 14b,c, Reaction of this dimer with OH - yielded 1 (Figure A). The second step in this approach is rather vaguely defined with regard to the number of equivalents of OH - required and whether the synthesis requires O 2 as a “catalyst”.…”

“…A survey of the literature provides a number of examples of molecules with the general formulation [((L)(L‘)MoO 2 ) 2 (μ-O)] n - (L = L‘ = 9,10-phenanthrenesemiquinone, N -(2-mercaptoethyl)- N ‘, N ‘-dimethylethylenediamine, or N , N -bis(2-pyridylmethyl)-2-mercaptoethylamine, n = 0; L = phenanthroline, L‘ = NCS - , n = 0; L = L‘ = catecholate, , nitrilotriacetate (NTA), or citrate; n = 2; L = tetrachlorocatecholate, L‘ = pyridine 19 or L = oxalate, L‘ = H 2 O, n = 2). Except for (pyH) 2 [[(py)(Cl 4 -cat)MoO 2 ] 2 (μ-O)], these complexes are generally formed from the reaction of MoO 3 or MoO 4 2- and the conjugate acid of the ligand in aqueous medium or from MoO 2 (acac) 2 and the conjugate acid in organic solvents.…”

Bioinspired Mo, W and V complexes bearing a highly hydroxyl-functionalized Schiff base ligand

“…[29][30][31][32][33] There are also some reports for catecholate-containing molybdenum and even tungsten complexes. [34] In the case of vanadium(V) complexation of catechols may lead to a reduction in the metal center (V(V) → V(IV)), sometimes accompanied by cleavage of the oxido ligand. [30,31,33] The mechanism(s) of vanadium-catalyzed oxidation of catechols are still not fully understood.…”