Three zinc iodide complexes based on phosphane ligands: Syntheses, structures, optical properties and TD-DFT calculations

Article abstract of DOI:10.1107/S2053229618002607

Three zinc iodide complexes based on phosphane ligands, namely diiodidobis(triphenylphosphane-κP)zinc(II), [ZnI₂(C₁₈H₁₅P₂)₂], (1), diiodidobis[tris(4-methylphenyl)phosphane-κP]zinc(II), [ZnI₂(C₂₁H₂₁P₂)₂], (2), and [bis(diphenylphosphoryl)methane-κ²O,O′]zinc(II) tetraiodidozinc(II), [Zn(C₂₅H₂₂O₂P₂)₃][ZnI₄], (3), have been synthesized and characterized. Single-crystal X-ray diffraction revealed that the structures of (1) and (2) are both mononuclear four-coordinated ZnI₂ complexes containing two monodentate phosphane ligands, respectively. Surprisingly, (2) spontaneously forms an acentric structure, suggesting it might be a potential second-order NLO material. The crystal structure of complex (3) is composed of two parts, namely a [Zn(dppmO₂)₃]²⁺ cation [dppmO₂ is bis(diphenylphosphoryl)methane] and a [ZnI₄]^2- anion. The UV-Vis absorption spectra, thermal stabilities and photoluminescence spectra of the title complexes have also been studied. Time-dependent density functional theory (TD-DFT) calculations reveal that the low-energy UV absorption and the corresponding light emission both result from halide-ligand charge-transfer (XLCT) excited states.ZnI₂(PPh₃)₂ and ZnI₂[(p-Tol)₃P]₂ (p-Tol is p-toluene) are both mononuclear four-coordinated ZnI₂ complexes, while [Zn(dppmO₂)₃][ZnI₄] [dppmO₂ is bis(diphenylphosphoryl)methane] is composed of a [Zn(dppmO₂)₃]²⁺ cation and a [ZnI₄]^2- anion. The acentric space group of ZnI₂[(p-Tol)₃P]₂ suggests it as a potential second-order NLO material. A TD-DFT study demonstrates that the photoluminescence should be derived from the emissive XLCT excited state.

Full text of DOI:10.1107/S2053229618002607

Acta Cryst. (2018). C74, doi:10.1107/S2053229618002607
Supporting information
Volume 74 (2018)
Supporting information for article:
Syntheses, structures, optical properties and TD–DFT calculations
of three zinc iodide complexes based on phosphane ligands
Di Chen, Qiu-Hua Wang, Wen-Xiang Chai and Li Song

Acta Cryst. (2018). C74, doi:10.1107/S2053229618002607
Supporting information, sup-1
Figure S1 Experimental and calculated IR spectra of: (a) complex 1, and (b) complex 2.