Syntheses, Structures And Properties Of Transition Metal Complexes Based On Pyridyl Ligands

The syntheses, magnetic properties and catalytic activities of transition metal complexes based on pyridyl ligands were reported. Fifteen coordination complexes were synthesized by reactions of transition metal ions with the pyridyl ligands. The catalytic behaviors of two complexes toward ketalization reaction of 2-butanone and ethylene glycol were determined. The magnetic properties of four complexes were investigated, and the fluorescence properties of two complexes were studied. The main results are as follows:Four polynuclear coordination polymers of the compositions {Ni₂(C₂H₅OH) (C₆NO₂H₄)(L1)₂Cl₃} (1), [{Ni₆(L1)₆(C₇H₅O₂)₆}]·2EtOH (2), [{Ni₆(L1)₆(C₇H₅O₂)₆ Cl₆}]·3EtOH (3), {Cu₄(OCH₃)₂(C₅H₆N₂O₂)₂(L1)₂(NO₃)₂} (4) were synthesized by using pyridyl ligand HL1 (HL1 = 2-pyridinealdoxime) as primary ligand and aromatic or 2-picolinic acids as the ancillary ligands. X-ray single crystal diffraction and IR analyses showed that 1-4 are carboxyl oxygen- or chloro-bridged complexes. Variable-temperature magnetic susceptibilities of 1 have been measured in the temperature range of 2-300 K, and ferromagnetic interactions are present in 1. In complex 4, the ligand HL1 was changed to N-hydroxypicolinamide, and the possible reaction mechanism was proposed.Five novel coordination polymers of the formula [Cu4ICuII(L2)₄(H₂O)2Cl₂]_n(5),{[Co(L2)₂]·H₂O}_n (6), {[Ni(L2)₂]·H₂O}_n (7), {[Mn(mtpo)₂]·CH₃OH}n (8), [Zn(at)Cl]_n (9) based on HL2 (HL2 = Hmtpo) ligand were synthesized. Mixed valence state CuI/CuII was found in 5. Complex 5 can catalyze the ketalization reaction of 2-butanone and ethylene glycol. Variable-temperature magnetic susceptibilities of 6 have been determined in the temperature range of 2-300 K, and anti-ferromagnetic interactions are present in 6. Complexex 7 and 8 exhibited the similar 3-D network structure. The at- ligand of 9 was formed in situ by the C-N cleavage of the HL2 ligand. Complex 9 can also be synthesized by using Hat as the starting material.Six novel coordination polymers of the compositions [Co₂(HL5)₂Cl₄]·EtOH (10), [Cu2(HL4)2Cl4] (11), [Cu(HL4)(SCN)]_n (12), [Fe(HL3)₂(SCN)Cl] (13), [Fe(HL3)₂ (SCN)₂] (14), [Mn(HL3)₂Cl₂] (15) were synthesized based on the ligands HL3-HL5 (HL3 = 2-(4,5-bis(3-chlorophenyl)-1H-imidazol-2-yl)pyridine, HL4 = 2-(4,5-bis (4-chlorophenyl)-1H-imidazol-2-yl)pyridine, HL5 = 2-(4,5-bis(2-chlorophenyl) -1H-imidazol-2-yl) pyridine) and ancillary ligand KSCN. Variable- temperature magnetic susceptibilities of 10 and 11 have been examined in the temperature range of 2-300 K. Anti-ferromagnetic interactions are present in 10, and ferromagnetic interactions are determined in 11. Complex 12 can catalyze the ketalization reaction of methyl ethyl ketone and ethylene glycol ketal. The fluorescence properties of 13 and 15 were investigated.