Ruthenium, copper and ruthenium-copper complexes of an unsymmetrical phosphino pyridyl 1,8-naphthyridine PNNN ligand

• Published in: Dalton transactions : an international journal of inorganic chemistry 2024-11, Vol.53 (44), p.1837-1846
• Main Authors: Wu, Jingyun, Stevens, Michael A, Gardiner, Michael G, Colebatch, Annie L
• Format: Article
• Language: English
• Subjects: Coordination; Copper chloride; Copper compounds; Ligands; Ruthenium
• ISSN: 1477-9226; 1477-9234; 1477-9234
• DOI: 10.1039/d4dt02755h

A new unsymmetrical dinucleating phosphino pyridyl 1,8-naphthyridine ligand PNNN is reported. Reaction with CuCl gave the dicopper complex [Cu 2 (μ-Cl) 2 (PNNN)] ( 1 ). In contrast, complexation of [RuCl 2 (cymene)] 2 yielded a monometallic species [RuCl(cymene)(PNNN)]Cl ( [2]Cl ) in which the Ru is bound to the κ 2 -N,N, rather than κ 2 -P,N, binding pocket. The selective formation of the monoruthenium complex [2]Cl enabled synthesis of heterobimetallic complexes [RuCuCl 3 (cymene)(PNNN)] ( 3 ) and [RuCuCl 2 (cymene)(PNNN)] 2 [PF 6 ] 2 ( [4] 2 [PF 6 ] 2 ), which both exhibit κ 1 -P coordination of Cu. Complexes 1 and [4] 2 [PF 6 ] 2 exhibit reversible dearomatisation-aromatisation behaviour at the metal-ligand cooperative methylene site upon sequential treatment with base (KO t Bu) and acid (HCl). Notably, deprotonation of [4] 2 [PF 6 ] 2 induces a shift in the coordination mode of Cu to κ 2 -P,N. A new unsymmetrical dinucleating PNNN ligand is reported, the versatility of which is demonstrated by formation of heterobimetallic, homobimetallic and monometallic complexes.