title: Aromatic versus heteroradialene character in extended thiophloroglucinol ligands and their trinuclear nickel(II) complexes.
abstract: Extended phloroglucinol ligands and complexes are best described as nonaromatic heteroradialenes. Herein, the electronic structures of extended thiophloroglucinol ligands and their Ni(II) 3 complexes are evaluated by comparison to their phloroglucinol analogs by means of NMR, FTIR, UV/Vis, and structural parameters. To provide a full set of compounds for this comparison of S versus O substitution, a new triplesalen ligand, its Ni(II) 3 complex, and a new thiophloroglucinol were synthesized. (1) H and (15) N NMR chemical shifts and coupling constants prove that the thiophloroglucinol ligands exist as the N-protonated and not the O-protonated tautomer. (13) C and (15) N NMR chemical shifts and structural parameters further demonstrated that the extended thiophloroglucinol ligands must be described with a predominant thione-enamine (heteroradialene) character despite the participation of a CS double bond. In the Ni(II) 3 complexes, this heteroradialene character is reduced but still predominant.
authors: Lehrstuhl für Anorganische Chemie I, Fakultät für Chemie, Universität Bielefeld, Universitätsstrasse 25, 33615 Bielefeld (Germany).
authors: Bastian
authors: B
authors: Feldscher
authors: Anja
authors: A
authors: Stammler
authors: Hartmut
authors: H
authors: Bögge
authors: Thorsten
authors: T
authors: Glaser
keywords: electronic structure; heteroradialenes; ligand design; nickel; trinucleating ligands