Investigation of the MSO 4 · xH 2O (M = Zn, x = 7; M = Cd, x = 8/3)/methyl 2-pyridyl ketone oxime reaction system: A novel Cd(II) coordination polymer versus mononuclear and dinuclear Zn(II) complexes

Abstract

The reactions of methyl 2-pyridyl ketone oxime, (py)C(Me)NOH, with MSO 4 · xH 2O (M = Zn, x = 7; M = Cd, x = 8/3), in the absence of an external base, have been investigated. The synthetic study has led to the two new complexes [Zn(SO 4){(py)C(Me)NOH}(H 2O) 3] · H 2O ( 1 · H 2O) and [Zn 2(SO 4) 2{(py)C(Me)NOH} 4] · (py)C(Me)NOH [ 2 · (py)C(Me)NOH], and the coordination polymer [Cd(SO 4){(py)C(Me)NOH}(H 2O)] n · [Cd(SO 4){(py)C(Me)NOH}(H 2O) 2] n ( 3). In the three complexes the organic ligand chelates through its nitrogen atoms. The sulfate anion in 1 · H 2O is monodentate; the complex molecule is the mer isomer considering the positions of the aqua ligands. The Zn II centers in 2 · (py)C(Me)NOH are bridged by two syn, anti η 1:η 1:μ 2 SO 4 2 - ligands; each metal ion has the cis– cis– trans disposition of the coordinated sulfate oxygen, pyridyl nitrogen and oxime nitrogens, respectively. The molecular structure of 3 is unique consisting of two different linear and ladder – type chains. π–π stacking interactions and/or hydrogen bonds lead to the formation of interesting supramolecular architectures in the three complexes. The thermal decomposition of complex 3 has been studied. Characteristic vibrational (IR, Raman) bands are discussed in terms of the nature of bonding and the structures of the three complexes.