New nine and ten coordinated complexes of lanthanides with bidentate 2-pyrazinecarboxylate containing hydrazinium cation

The new hydrazinium lanthanide metal complexes of 2-pyrazinecarboxylic acid of the formulae (N2H5)2[Ln(pyzCOO)5] · 2H2O (1), where Ln = La or Ce and (N2H5)3[Ln(pyzCOO)4(H2O)] · 2NO3 (2), where Ln = Pr, Nd, Sm or Dy have been synthesized by the addition of an aqueous solution of corresponding metal nitrate hydrates to an aqueous mixture of carboxylic acid and hydrazine hydrate in an appropriate ratios. The structure of (N2H5)2[La(pyzCOO)5] · 2H2O (1a) and (N2H5)3[Nd(pyzCOO)4(H2O)] · 2NO3 (2a) have been determined from single crystal X-ray analysis. Coordination numbers from six to twelve have been established in lanthanide compounds but ten coordination appears rarely. This work reports the first ten coordinated hydrazinium lanthanide complexes with carboxylate anions. The structure contains lanthanum ions joined by 2-pyrazinecarboxylate groups forming two-dimensional sheets parallel to (0 0 1) plane. 2a is monomeric in nature and the structure comprises of N2H5+ cations, [Nd(pyzCOO)4(H2O)]− and View the MathML sourceNO3- anions. The neodymium is nine coordinated with four pyzCOO lignads, bidentate (N,O) to the metal and the lone water molecule completes the coordination sphere and the sheets like pattern in all are interlinked via multiple hydrogen bonds leading to three dimensional structure.