Studies of the binding modes of carboxylate donors with manganese(III) complexes containing tetradentate Schiff base ligands. Crystal structures of the complexes [Mn(3-CH(3)Osalpn)(HO2CC6H4CO2)](n) and [{Mn(5-NO(2)salpn)(OH)(H2O)} {Mn(5-NO(2)salpn)-(HO2CC6H4CO2)(H2O)}]center dot C2H5OH

Manganese(III) complexes of stoichiometry MnL(HO2CRCO2)(H2O)(n) (L = 3-CH(3 )Osalpn, 3,5-CH(3)Osalpn, 5-NO(2)salpn, 3-Br, 5-NO(2)salpn; R = o-C6H4, CH2 , C2H4, C3H6 and n = 0-3) have been synthesised. The compounds have been ch aracterised by elemental analyses, IR spectroscopy, fast atom bombardment m ass spectrometry (FAB) and magnetic susceptibility measurements. The X-ray structure of [Mn(3-CH(3)Osalpn)(HO2CC6H4CO2)](n) (1) has been determined. T he hydrogenphthalate ligands link the manganese centres into polymeric chai ns. Slow evaporation of an ethanol solution of [Mn(5-NO(2)salpn)(HO2CC6H4CO 2)(H2O)] yielded [{Mn(5-NO(2)salpn)(OH)(H2O)}{Mn(5-NO(2)salpn)(HO2CC6H4CO2) (H2O)}]. C2H5OH (2), also crystallographically characterised. The two cocry stallised Mn(III) complexes an monomeric, with a distorted octahedral geome try, and they interact by hydrogen bond and pi-pi stacking. In both 1 and 2 , the hydrogenphthalate ligand is monoanionic, however, the coordination mo de of this carboxylate is found to differ, showing the versatility of carbo xylates as ligands. (C) 1999 Elsevier Science S.A. All rights reserved.