Syntheses, structures and properties of cadmium(II) halide complexes containing tridentate Schiff bases

Abstract

<span style="mso-bidi-font-weight:bold" lang="EN-GB">Three neutral mononuclear complexes of the type [Cd(L1)I₂] (<b style="mso-bidi-font-weight:normal">1</b>) [L1 = (N,N-diethyl,N'-(pyridin-2-yl)formylidene)ethane-1,2-diamine] and [Cd(L2)X₂] [L2 = (N,N-diethyl,N'-(pyridin-2-yl)benzylidene)ethane-1,2-diamine; X = Br_­^- (<b style="mso-bidi-font-weight:normal">2</b>), I^- (<b style="mso-bidi-font-weight:normal">3</b>)] are isolated using one-pot reactions of cadmium(II) halides and tridentate Schiff bases (L1 and L2) in a 1:1 molar ratio in MeOH solutions at room temperature. The compounds are characterized by elemental analyses and spectroscopic and other physicochemical data. Single-crystal X-ray diffraction analyses of (<b style="mso-bidi-font-weight: normal">1</b>)-(<b style="mso-bidi-font-weight:normal">3</b>) show that cadmium(II) center in each complex adopts a distorted square pyramidal geometry bound by three N atoms of L1/L2 and two terminal halides.Intermolecular π…π interactions in (<b style="mso-bidi-font-weight:normal">1</b>), cooperative C-H…Br hydrogen bonds and C-H…π interactions in (<b style="mso-bidi-font-weight:normal">2</b>) and C-H…π interactions in (<b style="mso-bidi-font-weight:normal">3</b>) lead to different crystalline architectures. T<span style="mso-bidi-font-style:italic">hermogravimetric analyses show that the compounds have reasonable thermal stabilities. The complexes display ligand-centered π–π^* fluorescence in DMF solutions at room temperature.

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