Structural diversity in the reactions of 4′-(pyridyl)-2,2′:6′,2″-terpyridine ligands and bis{4′-(4-pyridyl)-2,2′:6′,2″-terpyridine}iron(II) with copper(II) salts

We have demonstrated that treatment of [Fe(1)2]2+ (1 = 4′-(4-pyridyl)-2,2′:6′,2″-terpyridine) with an excess of CuCl2·2H2O leads to competition between coordination of copper(II) by the pendant pyridine donors in [Fe(1)2]2+, and transfer of ligand 1 from iron(II) to copper(II) to yield [{Cl3Cu(µ-1)Fe(µ-1)}2CuCl2(OH2)2]Cl2·4H2O and [Cu(H1)Cl2]Cl·4H2O, respectively. Direct reaction of 1 with CuCl2·2H2O and variation in crystallization conditions results in the formation of either monomeric or polymeric complexes: [Cu(1)Cl2]·4.75H2O, [Cu(1)Cl2]·H2O·MeOH and [Cu(1)Cl2·2H2O]n. The reaction of 1 with Cu(NO3)2·3H2O gives the coordination polymer [Cu(1)(ONO2)2·H2O]n. Magnetic data for [Cu(1)Cl2·2H2O]n and [Cu(1)(ONO2)2·H2O]n are consistent with antiferromagnetically-coupled chains. Reactions of CuCl2·2H2O with ligands 2 and 3 (2 = 4′-(3-pyridyl)-2,2′:6′,2″-terpyridine, 3 = 4′-(2-pyridyl)-2,2′:6′,2″-terpyridine) lead to monomeric complexes. With the exception of [Cu(3)Cl2], the mononuclear complexes show a propensity for the incorporation of water into their crystal lattices; in the case of [Cu(H1)Cl2]Cl·4H2O and [Cu(H1)Cl2]Cl·4.75H2O, the small change in water content leads to the assembly of (5.82)2(5.6.8)4(52.6)2 or (42.62)3(4.62)6water–chloride ion nets.