Mononuclear low-spin 3:1-type iron(ii) complexes of 4-substituted 3,5-bis(2-pyridyl)-and 3-phenyl-5-(2-pyridyl)-4h-1,2,4-triazoles

摘要

Two series of mononuclear 3:1-type iron(II) complexes were obtained by the reaction of Fe(C10_4)_2·6H_2O with nine previously reported 1,2,4-triazole-based ligands. The first series, [Fe ~(II)L~s_3](C10_4)_2· nH_2O, is based on symmetrical 4-substituted 3,5-bis(2pyridyl)-4H-l,2, 4-triazoles where L~s = medpt [4-methyl-3,5-bis(2pyridy1)-4H-l,2,4- triazole], ibdpt [4-isobutyl-3,5-bis(2-pyridy1)-4H1,2,4-triazole], pmdpt [4-(4-methylphenyl)-3,5-bis(2-pyridy1)-4H1,2,4-triazole], pydpt [3,5-bis(2-pyridyl)-4-(4-pyridyl)-4H-1,2,4-triazole] and pldpt [3,5-bis(2-pyridyl)-4-(ltf-pyrrol-1-yl)-4H-1,2,4-triazole], whereas the complexes of the second series, [Fe~(II)L~u_3](C10_4)_2·nH_2O, incorporate unsymmetrical 4-substituted 3-phenyl-5-(2-pyridyl)-4H-1,2,4-triazoles with L~U = meppt [4-methyl-5-phenyl3-(2-pyridyl)-4H-1,2,4-triazole], ibppt [4-isobutyl-3-phenyl-5-(2-pyridyl)-4H-l,2,4-triazole], pmppt [4-(4-methylphenyl)-3-phenyl-5-(2pyridyl)-4H-1,2,4-triazole] and pyppt [3-phenyl-5-(2-pyridyl)-4-(4pyridyl)-4H-1,2,4-triazole]. The complexes were investigated by ~1H NMR spectroscopy and found to be in the low-spin state at room temperature. Single crystal X-ray diffraction studies of the complexes [Fe~(II)(pmdpt)_3](C10_4) _2·CH_3CN.0.5H_2O(I), [Fe ~(II)(ibdpt)_3](C10_4)_2.2H_2O (II) and [Fe~(II)(ibppt)_3](BF_4) _2.1.34CH_3OH.0.16H_2O (III) revealed meridional arrangements of the ligands and distorted octahedral FeN_6 coordination environments around the respective low-spin iron(II) atoms.