Preparation and electrochemistry of six-coordinate monooxo molybdenum(VI) complexes containing bidentate catecholate and tridentate NOS-donor Schiff base ligands

Six-coordinate monooxo molybdenum(VI) complexes with N-4-diethylaminosalicylidene-N′-4-nitrobenzoyl hydrazine and catechol ligands: preparation and spectroscopic properties

“…The long wave-length band at 655-658 nm attributed to cat ! Mo charge transfer is consistent with absorptions at similar energies in other MoO 4+ -catecholate complexes [11][12][13]. The MoO(cat)L complexes are assigned the structure shown in 3.…”

“…However many seven-coordinate [4-8] and some six-coordinate [9] complexes with MoO 4+ moiety have been prepared and examined for spectroscopic and redox properties [10]. We have synthesized a number of six-coordinate monooxo Mo(VI) complexes by coordinating bidentate catecholate (cat 2À ) and tridentate Schiff base ligands with ONO, ONS, and OSO donor-atom sets to MoO 4+ [11][12][13]. The present paper reports the preparation and spectroscopic characterization of several Mo(VI) complexes containing the Schiff base N-4-diethylaminosalicylidene-N 0 -4-nitrobenzoyl hydrazine (LH 2 , 1) and catechol (2a-d) ligands.…”

“…The negative shift of m C@N at 1593 cm À1 and the positive shift of m N-N at 1132 cm À1 of the free ligand by 10-12 and 6-9 cm À1 , respectively, in all Mo(VI) complexes indicate coordination of the azomethine nitrogen to Mo [16,17]. MoO(cat)L complexes exhibit a single IR absorption at 935-938 cm À1 which is characteristic of Mo@O stretching vibration of the MoO 4+ group in the six-coordinate complexes containing Schiff base ligands [9,11,12]. The geometrical isomerism for the unsymmetrically substituted catechol complexes, MoO (Mecat)L and MoO(DTBcat)L is possible [8(a),12].…”