Mononuclear anionic octahedral cobalt(III) complexes based on N-salicylidene-o-aminophenol and its derivatives: Synthetic, structural and spectroscopic studies

• Octahedral cobalt(III) complexes of tridentate Schiff bases have been prepared.
• The structures of the complexes have been determined by X-ray crystallography.
• The complexes were studied by spectroscopic techniques (IR, Raman, UV/VIS, NMR).

The reactions of Co(II) sources with N-salicylidene-o-aminophenol (H2saph), N-salicylidene-o-amino-4-methylphenol (H2saph-4Me) and N-salicylidene-o-amino-4-chlorophenol (H2saph-4Cl) were studied in MeOH. The new solid complexes (Bu4nN)[CoIII(saph)2] (1), (Et3NH)[CoIII(saph-4Me)2]⋅MeOH⋅MeCO2H (2⋅MeOH⋅MeCO2H) and (Et3NH)[CoIII(saph-4Cl)2]⋅MeOH⋅MeCO2H (3⋅MeOH⋅MeCO2H) have been isolated and their structures determined by single-crystal, X-ray crystallography. The three compounds contain the mononuclear, low- spin octahedral anion [CoIIIL2]-[CoIIIL2]- (H2L = H2saph, H2saph-4Me, H2saph-4Cl), in which both L2− ligands act as tridentate chelating, meridional ONO donors. The crystal structures of 2⋅MeOH⋅MeCO2H and 3⋅MeOH⋅MeCO2H are built through H-bonding and π–π stacking interactions. The new complexes were characterized by elemental analyses and spectroscopic (IR, Raman, UV/VIS, 1H NMR) data. All data are discussed in terms of the nature of bonding and known structures.

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