Structural diversity in Cu(i) complexes of the PNP ligand: from pincer to binuclear coordination modes and their effects upon the electrochemical and photophysical properties. Issue 39 (26th September 2017)

• Record Type: Journal Article
• Authors: Arce, Pablo; Vera, Cristian; Escudero, Dayra; Guerrero, Juan; Lappin, Alexander; Oliver, Allen; Jara, Danilo H.; Ferraudi, Guillermo; Lemus, Luis
• Is Part Of: Dalton transactions. Volume 46:Issue 39(2017)
• Page Start: 13432
• Page End: 13445
• Publication Date: 2017-09-26
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c7dt02244a
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : The versatility of PNP ligand in coordinating to Cu(i ) resulted in the formation of emissive complexes with notable structural differences. Abstract : 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 (PPh3, phen or dmp) allows the formation of new complexes: a bimetallic helicate [CuI2(PNP)2 (phen)] 2+, (2), a mononuclear pincer complex [Cu I (PNP)(PPh3 )] +, (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 –PPh2 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).