Three isomers in a (hydrogen L-Cysteinato)-thallium(I): Crystal structure, spectroscopic and thermal properties

The isolation of thallium(I) complexes [Tl-2(HCys)(2)](n) (1) and [Tl-4(HCys)(4)](n) (2) {H(2)Cys = L-Cysteine} from aqueous solution by means of crystallization is reported herein. Polar crystals of 1 and 2 were crystallized in P2(1) and P2(1)2(1)2(1) space groups respectively. Elemental analysis, XRD, IR, UV-Vis, TG-DSC and a single crystal X-ray diffraction were applied for characterizing the compounds. Linkage isomers 1 and 2 have 1D and 2D coordination polymeric structures respectively. The lone pair electrons of thallium(I) in 1-2 are stereo-chemically active. In 1, each of two independent Tl+ ions is coordinated by three HCys(-) ions forming TlS3O irregular polyhedron that is linked to each other by vertexes in an infinite chain. In 2, four independent Tl+ ions are coordinated by HCys(-) ions through S and O atoms, forming Tl1S(3)O(2), Tl2S(4), Tl3S(3), Tl4S(3) irregular polyhedrons. The crystallographic independent HCys(-) ions are linked to the metal ion differently, two are mu(3)-S,S,S-, one is mu(4)-O,S,S,S-, and one is mu(4)-O,O',S,S,S-coordinated ligands. The amine group of compounds 1 and 2 is in the form of an ammonium ion (-NH3+). The structures of 1-2 are stabilized by N-H center dot center dot center dot O hydrogen bonds, thallophilic Tl center dot center dot center dot Tl and anagostic Tl center dot center dot center dot H-C interactions. The spectroscopic and thermal properties of compounds were analyzed. (C) 2019 Elsevier Ltd. All rights reserved.