Investigation of the MSO4 · xH2O (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

The reactions of methyl 2-pyridyl ketone oxime, (py)C(Me)NOH, with MSO4 · xH2O (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(SO4){(py)C(Me)NOH}(H2O)3] · H2O (1 · H2O) and [Zn2(SO4)2{(py)C(Me)NOH}4] · (py)C(Me)NOH [2 · (py)C(Me)NOH], and the coordination polymer [Cd(SO4){(py)C(Me)NOH}(H2O)]n · [Cd(SO4){(py)C(Me)NOH}(H2O)2]n (3). In the three complexes the organic ligand chelates through its nitrogen atoms. The sulfate anion in 1 · H2O is monodentate; the complex molecule is the mer isomer considering the positions of the aqua ligands. The ZnII centers in 2 · (py)C(Me)NOH are bridged by two syn, anti η1:η1:μ2SO42- 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.

Graphical abstractThe shown reaction schemes yield one mononuclear zinc complex, one dinuclear zinc compound with two sulfato bridges and a unique cadmium coordination polymer possessing two different (one linear, the other ladder) chains; π–π stacking interactions and/or hydrogen bonds create interesting supramolecular architectures.Figure optionsDownload full-size imageDownload as PowerPoint slide