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

Abstract Using a non-planar tridentate ligand 2,6-bis(pyrazol-1-ylmethyl)pyridine (L 5 ) two new coordination complexes [(L 5 )Co II (H 2 O) 3 ]Cl 2 ( 1 ) and [(L 5 )Ni II (H 2 O) 2 Cl]Cl·H 2 O ( 2 ) have been synthesized and structurally characterized. Complex 1 has N 3 O 3 distorted octahedral environment around Co II with coordination by L 5 (two pyrazole and a pyridine nitrogen in a facial mode) and three water molecules. Complex 2 has N 3 O 2 Cl distorted octahedral geometry around Ni II with meridional L 5 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.