Coumarin-naphthohydrazone ligand with a rare coordination mode to form Mn(II) and Co(II) 1-D coordination polymers: synthesis, characterization, and crystal structure

The hydrazone (E)-3-hydroxy-N'-(1-(2-oxo-2H-chromen-3-yl)ethylidene)-2-naphthohydrazide (H2L) was synthesized from the reaction of 3-acetylcoumarin and 3-hydroxy-2-naphthoic hydrazide in methanol. Compounds [Mn(H2L)(NO3)(2)(CH3OH)]?CH3OH (1a), [Mn(HL)(NO3)(CH3OH)](n) (1b), [Co(HL)(NO3)(CH3OH)](n) (2), and [Cu(HL)(NO3)] (3) were obtained by reaction of an equimolar amount of H2L with nitrate salts of Mn(II), Co(II), or Cu(II) in methanol. The reaction of ligand and Mn(NO3)(2)4H(2)O was also carried out in the presence of sodium azide which led to the 1-D coordination polymer, [Mn(HL)(N-3)(CH3OH)](n) (4). All of the synthesized compounds were characterized by elemental analyses and spectroscopic methods. Single-crystal X-ray analysis of 1-4 indicated that H2L is neutral (in 1a) or mononegative ligand (in 1b, 2, 3 and 4). In 1b, 2 and 4 the 1-D polymeric chain is found by a rare coordination mode of this kind of hydrazone ligand since the naphtholic oxygen is coordinated to the neighboring metal ions while the NH moiety of hydrazone remains intact, also confirmed by FT-IR spectroscopic studies. The thermal stability of 2 and 4 were also studied from 30-1000 degrees C. [GRAPHICS] .