Syntheses, X-ray structures and characterisation of luminescent chromium(III) complexes incorporating 8-quinolinato ligands. (1st January 2019)

• Record Type: Journal Article
• Authors: Al-Riyahee, Ali A.A.; Horton, Peter N.; Coles, Simon J.; Amoroso, Angelo J.; Pope, Simon J.A.
• Is Part Of: Polyhedron. Volume 157(2019)
• Page Start: 396
• Page End: 405
• Publication Date: 2019-01-01
• Subjects: Quinolate -- Chromium -- Structures -- Luminescence -- Complex; Chemistry, Inorganic -- Periodicals; Chimie inorganique -- Périodiques; Organometaalverbindingen; Anorganische chemie; 546.05
• DOI: 10.1016/j.poly.2018.10.019
• Languages: English
• ISSNs: 0277-5387

Abstract

Graphical abstract: A series of Cr(III) complexes have been synthesised that incorporate (substituted) 8-quinolinato type ligands into the coordination sphere. Both homo- and heteroleptic examples are described together with X-ray structures and luminescence properties. Abstract: A series of six coordinate homoleptic and heteroleptic Cr(III) complexes have been formed that incorporate 8-quinolinato ligands. Three classes of complex have been synthesised and characterised: (i) [Cr(Q)3 ]; (ii) [Cr(Q)2 (H2 O)2 ]Cl; (iii) [Cr(Q)(N^N)2 ](PF6 )2 (where Q is a ligand, 8-hydroxyquinoline, 8-hydroxy-2-methyl-quinoline, or 8-hydroxy-5-nitroquinoline; N^N = 1, 10-phenanthroline or 2, 2′-bipyridine). Single crystal X-ray structures were obtained for four complexes giving examples of [Cr(Q)2 (H2 O)2 ]Cl, two [Cr(Q)(bipy)2 ](PF6 )2 and [Cr(Q)(phen)2 ](PF6 )2 . Each complex shows the ligands in the expected coordination mode with a distorted octahedral geometry evident at the metal centre. The UV–Vis. absorption data allowed assignments of the quinolinato-centred electronic transitions together with a much weaker spin allowed d–d transition ( 4 A2 → 4 T2 ) around 550 nm. Each complex was found to be luminescent in aerated MeCN solution at room temperature, which was attributed to a ligand-centred fluorescence based on the coordinated quinolinato ligand.