Anionic effects on the formation of tridentate 4′-chloro-2,2′:6′,2″-terpyridine copper(II) complexes having 1:1 or 1:2 ratio of metal and ligand and their crystal symmetry

A facile synthetic procedure has been used to prepare one five-coordinate and four six-coordinate copper(II) complexes of 4′-chloro-2,2′:6′,2″-terpyridine (tpyCl) ligand with different counterions (SO42-, NO3-, BF4-, PF6-, and ClO4-) in high yields. They are formulated as [Cu(tpyCl-κ3N,N′,N′′)(SO4-κO)(H2O-κO)] · 2H2O (1), trans-[Cu(tpyCl-κ3N,N′,N″)(NO3-κO)2(H2O-κO)] (2), [Cu(tpyCl-κ3N,N′,N″)2](BF4)2 (3), [Cu(tpyCl-κ3N,N′,N″)2](PF6)2 (4) and [Cu(tpyCl-κ3N,N′,N″)2](ClO4)2 (5) and versatile interactions in supramolecular level including coordinative bonding, O–H⋯O, O–H⋯Cl, C–H⋯F, and C–H⋯Cl hydrogen bonding, π–π stacking play essential roles in forming different frameworks of 1–5. It is concluded that the difference of coordination abilities of the counterions used and the experimental conditions codominate the resulting complexes with 1:1 or 1:2 ratio of metal and ligand.

Graphical abstractFive tridentate 4′-chloro-2,2′:6′,2″-terpyridine copper(II) complexes with 1:1 or 1:2 metal/ligand ratio countered by five types of anions (SO42-, NO3-, BF4-, PF6-, and ClO4-) were described. Anionic effects on the formation of different metal/ligand ratio, crystallographic symmetry, molecular structures and packing patterns for these Cu(II) complexes were discussed.Figure optionsDownload full-size imageDownload as PowerPoint slide