RESUMEN
Schiff condensation of 2,6-diformyl 4-methylphenol with semicarbazide hydrochloride in 1:2 molar ratio produces the bis(semicarbazone) ligand, herein called H3L. A comprehensive spectroscopic analysis of the compound was performed by (1)H and (13)C NMR, FTIR and electronic spectroscopies. Assignments to the UV-vis spectrum of H3L were supported by semi-empirical quantum mechanics ZINDO/S calculations. The ligand H3L forms monoclinic crystals in the space group P21/c and its structure is stabilized by classic hydrogen bonds with propanone molecules. It promptly reacts with first row metal ions to produce the following coordination compounds: [Co2(L)(µ-NO3)]·DMF, [Ni2(H2L)(µ-CH3COO)(CH3COO)2]·2H2O, [Cu2(L)(µ-NO3)(H2O)2]·H2O, [Cu2(L)(µ-CH3COO)(H2O)2]·H2O and [Cu2(H2L)(µ-Cl)Cl2]·3H2O, that have different compositions, depending on the degree of deprotonation of the ligand upon coordination. Electronic and EPR spectroscopies as well as effective magnetic moment measurements of the complexes were used in an attempt to better understand their mode of coordination, the microsymmetry around the metal ions and magnetic properties.
RESUMEN
The mol-ecule of the title compound C7H8N4O·0.5H2O, alternatively called (E)-1-(pyridin-4-yl-methyl-ene)semi-carb-azide hemihydrate, is in the E conformation and is almost planar; the r.m.s. deviation of the positions of the atoms of the pyridine ring from the best-fit plane is 0.0039â Å. The C, N and O atoms of the rest of the mol-ecule sits close on this plane with a largest deviation of 0.115â (4)â Å for the O atom of the semicarbazone moiety. There is an intra-molecular N-Hâ¯N hydrogen bond. In the crystal, mol-ecules are linked into an infinite three-dimensional network by classical N-Hâ¯Os (s = semicarbazone) and Ow-Hâ¯N (w = water) hydrogen bonds.
