N,N ''-Substituted thioureas and their metal complexes: syntheses, structures and electronic properties

Al-Riyahee, Ali A. A.; Horton, Peter N.; Coles, Simon J.; Berry, Colin; Horrocks, Paul D.; Pope, Simon J. A.; Amoroso, Angelo J.

Abstract

The synthesis of six N,N'-substituted thiourea ligands (L1a-L3b) was achieved in two steps. A corresponding extensive series of Cu(I), Cu(II), Ni(II) and Zn(II) complexes (1-24) with varying formulations were synthesised from these ligands by the reaction of a 1?:?1 or a 1?:?2 mixture of Cu(II), Ni(II) and Zn(II) perchlorate or chloride salts. Complexes 1-24 have been comprehensively characterised by mass spectrometry, elemental analysis, UV-vis., IR, and 1H and 13C{1H} NMR spectroscopies where applicable. The X-ray crystal structures were obtained for eight examples: [(L1a)2Cu]ClO4 (1), [(L1c)2Zn](ClO4)2 (4), [(L2a)2Cu]ClO4 (6), [(L2c)2Ni](ClO4)2 (7), [(L1b)2Cu](ClO4) (15), [(L1b)CuCl] (16), [(L4)2CuCl2] (19) and [(L3b)CuClO4] (21). These studies reveal that L1c and L2c represent ligands that have undergone cleavage during reaction with the metal salt; L4 represents an intramolecular rearrangement (via a Hugershoff reaction) of L2b; and in most cases Cu(II) is reduced to Cu(I) during the ligand reaction. The X-ray crystal structures also reveal that 1, 4, 6, 15 and 16 are monometallic species in the solid state; that Cu(I) in 1, 6, 15 and 16 and Zn(II) in 4 are arranged in a distorted tetrahedral geometry; that Cu(I) in 21 adopts a trigonal planar geometry; and that in 7 and 19 the Ni(II) and Cu(II) centres, respectively, possess square planar geometry. Preliminary studies on the biological activity (using the Malaria Sybr Green I Fluorescence assay) of the thiourea containing complexes suggests that the d10 complexes, and increased ligand stoichiometries, may afford higher potency.

Citation

Al-Riyahee, A. A. A., Horton, P. N., Coles, S. J., Berry, C., Horrocks, P. D., Pope, S. J. A., & Amoroso, A. J. (2022). N,N ''-Substituted thioureas and their metal complexes: syntheses, structures and electronic properties. Dalton Transactions, 51(9), 3531-3545. https://doi.org/10.1039/d1dt04091j

• Journal Article Type: Article
• Acceptance Date: Jan 30, 2022
• Online Publication Date: Feb 10, 2022
• Publication Date: Mar 1, 2022
• Publicly Available Date: Jun 27, 2023
• Journal: Dalton Transactions
• Print ISSN: 1477-9226
• Publisher: Royal Society of Chemistry
• Peer Reviewed: Peer Reviewed
• Volume: 51
• Issue: 9
• Pages: 3531-3545
• DOI: https://doi.org/10.1039/d1dt04091j
• Public URL: https://keele-repository.worktribe.com/output/422629
• Publisher URL: https://doi.org/10.1039/D1DT04091J