Conformational flexibility of 2,6-bis(pyrazol-1-ylmethyl)pyridine (L5) in [(L5)CoII(H2O)3]Cl2 and [(L5)NiII(H2O)2Cl]Cl·H2O. Molecular structures and non-covalent interactions

Using a non-planar tridentate ligand 2,6-bis(pyrazol-1-ylmethyl)pyridine (L5) two new coordination complexes [(L5)CoII(H2O)3]Cl2 (1) and [(L5)NiII(H2O)2Cl]Cl·H2O (2) have been synthesized and structurally characterized. Complex 1 has N3O3 distorted octahedral environment around CoII with coordination by L5 (two pyrazole and a pyridine nitrogen in a facial mode) and three water molecules. Complex 2 has N3O2Cl distorted octahedral geometry around NiII with meridional L5 coordination, two water molecules, and a Cl− ion. Analysis of the crystal packing diagram reveals the involvement of solvent (water as metal-coordinated and as solvent of crystallization) and counteranion (Cl−) to play significant roles in generating 1D chains, involving O–H···Cl, and O–H···O interactions.