Title
Cooperative Metal–Ligand Influence on the Formation of Coordination Polymers, Conducting and Photophysical Properties of Tl(I) β-oxodithioester Complexes
Author
Chote Lal Yadav, Gunjan Rajput, Krishna Kumar Manar, Kavita Kumari, Michael Drew, Nanhai Singh
Year
2018
Journal
Dalton Transactions
Abstract
Eight novel Tl(I) β-oxodithioester complexes, [TlL]n (1–8) with ligands, L = methyl-3-hydroxy-3-(2-furyl)-2-propenedithioate (L1), methyl-3-hydroxy-3-(2-thienyl)-2-propenedithioate (L2), methyl-3-hydroxy-3-(3-pyridyl)-2-propenedithioate (L3), methyl-3-hydroxy-3-(4-pyridyl)-2-propenedithioate (L4), methyl-3-hydroxy-3-(9-anthracenyl)-2-propenedithioate (L5), methyl-3-hydroxy-3-(4-fluorophenyl)-2-propenedithioate (L6), methyl-3-hydroxy-3-(4-chlorophenyl)-2-propenedithioate (L7) and methyl-3-hydroxy-3-(4-bromophenyl)-2-propenedithioate (L8) have been synthesized and thoroughly characterized by elemental analysis, IR, UV-Vis., 1H, 13C{1H} NMR spectroscopy and their structures have been ascertained by X-ray crystallography. Complexes 1 and 2 crystallized in P21 and P212121 chiral space groups respectively and have been studied by Circular Dichroism (CD) spectra. The solid state structural analyses revealed the β-oxodithioester ligands are bonded to Tl(I) ions in a (O,S) chelating and chelating-bridging mode, thereby forming different types of 1D and 2D coordination polymeric structures. By considering the metal-assisted bonding interactions, varied coordination numbers of 5–8 and 10 have been established around the metal centre. Except for 5 and 7a which have Tl•••Tl separations at 3.724(1) and 3.767(1), 3.891(1) Å respectively, the remaining complexes have no Tl•••Tl distances <4.0 Å. This indicates the majority of structures contain only weak inter- and intramolecular thallophilic interactions. The structures of 1–8 highlight the role played by variations in substituents on the dithioester unit on the structure and properties of the complexes. The multi-dimensional assembly in these complexes rests on important non-covalent C–H•••π(TlOSC3, chelate), C–H•••X (X = F, Cl, O, N), C–H•••π, H•••H and rare Tl•••H–C intermolecular anagostic interactions. The Tl•••H–C anagostic interactions togetherwith C–O•••Tl and C–S•••Tl interactions formed 7-, 11- and 12-membered chelate ring about the metal centers. The anagostic interactions in 1, 2 and 7b have been assessed by theoretical calculations. All the complexes showed bright green luminescent emissions in solution and solid phases. Time-resolved emission spectra revealed a triexponential decay curve and short mean lifetime for fluorescence behavior.
Instrument
J-815
Keywords
Circular dichroism, Organic chemistry, Coordination chemistry, Solid state