Different complexation behavior of a proton transfer compound obtained from 1,10-phenanthroline and pyridine-2,6-dicarboxylic acid with InIII and CeIII: Synthesis, crystal structures and solution studies

Abstract

The different complexation methods of a proton transfer compound LH 2 , (phenH) 2 (pydc) (phenZ1,10-phenanthroline; pydcH 2 Z pyridine-2,6-dicarboxylic acid), are discussed and formation of [In 2 SO 4 (pydc) 2 (phen) 2 (H 2 O) 2 ]$5.5H 2 O (1) and {[Ce(pydc)(pydcH)(H 2 O) 2 ] $4H 2 O} n (2) are reported. The complexes were synthesized by reaction of LH 2 with In 2 (SO 4 ) 3 $xH 2 O and Ce(NO 3 ) 3 $6H 2 O, respectively. The characterization was performed using IR spectroscopy and X-ray diffraction. The complex 1 crystallizes in the space group P 1 of the triclinic system, with two molecules per unit cell. The unit cell parameters are aZ11.9547(6) Å , bZ12.8482(7) Å , cZ16.1313(8) Å , aZ89.532(1)8, bZ72.007(1)8 and gZ68.066(1)8. The crystal system of the complex 2 is monoclinic with space group P2 1 /c and four molecules per unit cell. The unit cell parameters are aZ14.0273(8) Å , bZ11.2184(6) Å , cZ12.9441(8) Å and bZ102.177(5)8. The complex 1 is a binuclear mixed-ligand system in which both phen and (pydc) 2K have contributed to the molecular structure as tri-and bi-dentate ligands, respectively. The complex 2 is a polymeric system in which only one of the fragments of LH 2 has acted as a ligand. In both complexes 1 and 2 a large number of hydrogen bonds are observed. These interactions especially in case of complex 2 play an important role in the formation of self associated systems in the crystal lattices. Results of the potentiometric pH titration studies in aqueous solution strongly confirm the formation of In III and Ce III complexes in solution with stoichiometries very similar to those of the crystalline complexes 1 and 2, respectively.

A brief review on structural concepts of novel supramolecular proton transfer compounds and their metal complexes

“…In [59] complex, 1,10-phenanthroline is removed completely upon complexation. The (pydc) 2-anion has a bridging role linking the fragments of the polymeric system through one of its carboxylate groups.…”

“…Distorted tricapped anti-prism [38] (pydaH) 2 Distorted square planar [53] (pydaH 2 )(phendc) a IR, NMR, UV-Vis, Es-Ms, elemental analysis -- [54] (pydaH) 2 [56] (phenH) 2 (pydc) a IR, 1 H, 13 [59] [HgCl 2 (phen) 2 ] b IR, crystal structure Monoclinic, P2 1 /c Distorted octahedral [60] (phenH) 2 …”

A novel proton transfer compound (a new molybdate salt) and its X-ray structure

“…An interesting report in this area was investigation of the mechanism of proton transfer from intra-molecularly hydrogen-bonded acids and differences between nitrogen-tooxygen and nitrogen-to-nitrogen proton transfer [6,7]. Whenever the hydrogen bonding associations result in complete proton transfer to the nitrogen atom, an ionic self-assembled compound is produced [8] and considerable stability upon structure-making process which can be used in designing of novel layered crystalline material is achieved [9,10].…”

Crystal structure of {(oxalato)-bis-[(pyridine-2,6-di-carboxylato)-diaqua)- indium(III)]}dihydrate: [In(C2O4)(C7H3N1O4)2(H2O)4]·2H2O, C16H18In2N2O18

“…Each carboxylate group of the oxa ligand functions as m 2 -bridge to link two different In(III)ions, forming adinuclear unit. The In1-N1 bond length is 2.236(4) Å, and the In1-O bond legnths are in the range of 2.139(4)Å to 2.306(3)Å,inaccordance with typical bond distances of reported In(III) complexes [11][12][13][14]. The O8-In1-O7 angle of the pentagonal bipyramid is 171.85(13)°and the other angles are in the range from 70.01 (13) to 146.92 (13) v ]w ith uncoordinated carboxylate oxygen atoms (O4) from an pdc ligand and coordinated water molecules (O8), respectively.…”