Structural diversity in Cu(i) complexes of the PNP ligand: from pincer to binuclear coordination modes and their effects upon the electrochemical and photophysical propertiesElectronic supplementary information (ESI) available: Additional tables and figures for NMR characterization and fluxional behavior, and emission information in PDF file. X-Ray crystallographic files of (1)-(4). CCDC 1522539, 1522540, 1522541 and 1522542. For ESI and crystallographic data in CIF or other electronic format se

• Main Authors: Arce, Pablo, Vera, Cristian, Escudero, Dayra, Guerrero, Juan, Lappin, Alexander, Oliver, Allen, Jara, Danilo H, Ferraudi, Guillermo, Lemus, Luis
• Format: Article
• Language: English
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c7dt02244a

A set of new copper( i ) complexes is synthesized and characterized using a labile PNP pincer ligand (PNP = N , N ′-bis(diphenylphosphine)-2,6-diaminopyridine). A homoleptic Cu( i ) complex [Cu(PNP-κ P 1 :κ N 1 ) 2 ] + , (1) , was prepared, and taking advantage of the uncoordinated phosphorus atoms in (1) , reaction with a second Cu( i ) atom bearing secondary ligands (PPh 3 , phen or dmp) allows the formation of new complexes: a bimetallic helicate [Cu I 2 (PNP) 2 (phen)] 2+ , (2) , a mononuclear pincer complex [Cu I (PNP)(PPh 3 )] + , (3) , and a heteroleptic complex [Cu I (PNP)(dmp)] + , (4) . All complexes were characterized by X-ray crystallography, NMR (VT-NMR for (1) and (4) ), cyclic-voltammetry, and steady-state and time-resolved luminescence spectroscopy. The fluxional behavior in (1) was studied by 31 P VT-NMR, where an E a value of 47.42 kJ mol −1 was calculated for the intramolecular alternating coordination of -PPh 2 moieties in PNP to the metal atom. This set of compounds reveals the versatility of the PNP ligand when added to the coordinating properties of Cu( i ). The four complexes exhibit emission in solution and complexes (2)-(4) display intense luminescence in the solid state. The oscillographic traces showing the decay of the luminescence were fitted to biexponential functions with time constants: 8.0 μs > τ em,1 > 0.37 μs and 50 μs > τ em, 2 > 2.2 μs for complexes (2) , (3) and (4) , respectively. Radiative relaxation is associated with electronic transitions in both the ligand PNP and metal-to-ligand charge transfer (MLCT). The versatility of PNP ligand in coordinating to Cu( i ) resulted in the formation of emissive complexes with notable structural differences.