Synthesis, Spectroscopic, Characterization and X-ray Structures of Lanthanide(III) Complexes Derived from 1,5-bis(phenyl(pyridin-2-yl)methylene)carbonohydrazide

The use of 1,5-bis (phenyl (pyridin-2-yl) methylene) carbonohydrazide (H2L) in the coordination chemistry of lanthanides (III) yielded complexes in which two ligand molecules are present. The synthesis was carried out using a Ln/H2L ratio of 1/2 to lead mononuclear complexes of [Ln(H2L)2(η -NO3)3-x](NO3)x (Ln=La (1), Sm (4), Gd (6) and Yb (7)), [Ln(H2L)2(NO3)3] (Ln=Pr(2), Eu(5) and a co-crystal {[Nd(H2L)2(η -NO3)2(η -NO3)], [Nd(H2L)2(η -NO3)(h NO3)(H2O)]}.(NO3).2CH3OH} (3). The structures of the complexes (2) and (3)were solved by X-ray crystallography on a single crystal. In the mononuclear complex of Pr, two neutral ligand molecules act in tridentate fashion. In the co-crystal complex, one of the Nd atom is coordinated by two ligand molecules acting tridentately in neutral form and three nitrate anions acting in bidentate fashion while the second Nd atom is coordinated by two ligand molecules acting tridentately in neutral form, one monodentate nitrate anion, one bidentate nitrate anion and one water molecule. The neutrality of the complex is ensured by one free nitrate anion. Two free methanol molecules are present. Complex (2) crystallizes in the triclinic space group P-1 with the following parameters: a=10.128 (2) Å, b=12.2285 (19) Å, c=20.816 (5) Å, α=85.634 (4), β=81.870 (4)°, γ=87.210 (5)°, V=2542.9 (9) Å, Z=2, R1=0.0640, wR2=0.1377. Complex (3) crystallizes in the monoclinic space group P21/c with the following parameters: a=10.4554 (12) Å, b=44.089 (6) Å, c=23.212 (3) Å, β=90.851 (2)°, V=10699 (2) Å, Z=4, R1=0.0630, wR2=0.1690. The coordination sphere of the twelve-coordinated Pr III atom is best described as distorted icosahedron. In the co-crystal one of the Nd atom is eleven-coordinated while the second Nd atom is ten-coordinated. The environments around the Nd atoms are respectively best described as distorted pentacapped trigonal prism and a distorted bicapped square antiprism, respectively. Supramolecular structures are consolidated by numerous hydrogen bonds.