Pii: S0020-1693(98)00354-5

The chemistry of the iron complexes of two Schiff-base ligands namely, N-2-mercaptophenyl-20-pyridylmethylenimine (PyASH, 1) and N-2-mercapto-2-methylpropyl-20-pyridylmethylenimine (PyMSH, 2) has been explored in a systematic manner. Use of DMF as solvent allows one to isolate the Fe(II) complexes in pure forms. The Fe(III) complexes [Fe(PyAS)2]X (X ˆ BF4, BPh4 (3)) and [Fe(PyMS)2]BPh4 (4) have been synthesized via oxidation of the corresponding Fe(II) complexes with ferrocenium salts. In 3 and 4, the deprotonated ligands are coordinated in mer fashion with two thiolato S donors cis to each other. The deprotonated PyASÿ ligand frames in 3 are essentially planar due to extensive electron delocalization. The Fe(III) centers of these two complexes remain low-spin in the temperature range 8± 300 K and exhibit rhombic EPR signals with small (gmax ÿ gmin) values. Results of this and other previously reported works suggest that tridentate Schiff-base ligands with N2S donor set (L) readily afford low-spin Fe(III) centers in [Fe (L)2] ‡ complexes. # 1999 Elsevier Science S.A. All rights reserved.