N, N′-Substituted thioureas and their metal complexes: syntheses, structures and electronic properties. Issue 9 (10th February 2022)

• Record Type: Journal Article
• Authors: Al-Riyahee, Ali A. A.; Horton, Peter N.; Coles, Simon J.; Berry, Colin; Horrocks, Paul D.; Pope, Simon J. A.; Amoroso, Angelo J.
• Is Part Of: Dalton transactions. Volume 51:Issue 9(2022)
• Page Start: 3531
• Page End: 3545
• Publication Date: 2022-02-10
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/d1dt04091j
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : Six different N, N ′-substituted thiourea ligands were synthesised and their coordination chemistry with Cu(i ), Cu(ii ), Ni(ii ) and Zn(ii ) was extensively studied to reveal interesting ligand reactivities, and potential biological activity. Abstract : The synthesis of six N, N ′-substituted thiourea ligands (L 1a –L 3b ) 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 1 H and 13 C{ 1 H} NMR spectroscopies where applicable. The X-ray crystal structures were obtained for eight examples: [(L 1a )2 Cu]ClO4 (1 ), [(L 1c )2 Zn](ClO4 )2 (4 ), [(L 2a )2 Cu]ClO4 (6 ), [(L 2c )2 Ni](ClO4 )2 (7 ), [(L 1b )2 Cu](ClO4 ) (15 ), [(L 1b )CuCl] (16 ), [(L 4 )2 CuCl2 ] (19 ) and [(L 3b )CuClO4 ] (21 ). These studies reveal that L 1c and L 2c represent ligands that have undergone cleavage during reaction with the metal salt; L 4 represents an intramolecular rearrangement ( via a Hugershoff reaction) of L 2b ; 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 d 10 complexes, and increased ligand stoichiometries, may afford higher potency.