Group 12 Metal Complexes of Semirigid 2,6-Pyridinediylbis(3-pyridinyl)methanone: Role of Counteranions and Solvent in Product Formation

Abstract

In a series of nine group 12 metal complexes of 2,6-pyridinediylbis(3-pyridinyl)methanone (abbreviated as L), namely, [Cd(L)2Cl2] (1), [Cd(L)2(NO3)2]·3.5H2O (2), [Cd(L)2(H2O)2](NO3)2 (3), [Cd(L)2(H2O)2](ClO4)2·H2O (4), {[Cd(L)(H2O)2](ClO4)2·1.5H2O}∞ (5), {[Cd(L)2SO4(H2O)]·2.8H2O}∞ (6), [Cd(L)2(CH3CO2)2]∞ (7), [Zn(L)2(CH3CO2)2]∞(8), and [Hg(L)2(CH3CO2)2]∞ (9), the semirigid multidentate ligand L exhibits flexible ligation modes I–IV in response to the cooperative effect of counteranions and solvent medium, leading to mononuclear (1–4), helical-chain (6), zigzag-chain (7), and 3D net (5) coordination motifs. The presence of the ancillary aqua ligand is essential for the crystallization of 3 and 5 by addition of deionized water to an organic mixed-solvent medium containing 2 and 4, respectively. The acetate complexes 7 (Cd2+), 8 (Zn2+), and 9 (Hg2+) are isostructural. Unconventional anion−π(pyridine), C═O···C═O, O(NO3–/ClO4–)···C═O, and cohesive nitrate···nitrate interactions are manifested in supramolcular ...