title: The binuclear dual emitter [Br(CO)3Re(PN)(NP)Re(CO)3Br] (PN): 3-chloro-6-(4-diphenylphosphinyl)butoxypyridazine, a new bridging P,N-bidentate ligand resulting from the ring opening of tetrahydrofuran.
abstract: Lithium diphenylphosphide unexpectedly provokes the ring-opening of tetrahydrofuran (THF) and by reaction with 3,6-dichloropyridazine leads to the formation of the ligand 3-chloro-6-(4-diphenylphosphinyl)butoxypyridazine (P⋯N), which was isolated. The reaction of this ligand with the (Re(CO)3(THF)Br)2dimer yields the novel complex [Br(CO)3Re(μ-3-chloro-6-(4-diphenylphosphinyl)butoxypyridazine)2Re(CO)3Br] (BrRe(P⋯N)(N⋯P)ReBr), which was crystallized in the form of a chloroform solvate, (C46H40Br2Cl2N4O8P2Re2)·(CHCl3). The monoclinic crystal (P21/n) displays a bimetallic cage structure with a symmetry inversion centre in the middle of the rhenium to rhenium line. The molecule shows two oxidation signals occurring at +1.50 V and +1.76 V which were assigned to the ReI/ReIIand ReII/ReIIImetal-centered couples, respectively, while signals observed at -1.38 V and -1.68 V were assigned to ligand centered reductions. Experimental and DFT/TDDFT results indicate that the UV-Vis absorption maximum of BrRe(P⋯N)(N⋯P)ReBr occurring near 380 nm displays a metal to ligand charge transfer (MLCT) character, which is consistent with CV results. Upon excitation at this wavelength, a weak emission (Φem< 1 × 10-3) is observed around 580 nm (in dichloromethane) which decays with two distinct lifetimes τ1and τ2of 24 and 4.7 ns, respectively. The prevalence of non-radiative deactivation pathways is consistent with efficient internal conversion induced by the high conformational flexibility of the P⋯N ligand's long carbon chain. Measurements in a frozen solvent at 77 K, where vibrational deactivation is hindered, show intense emission associated with the3MLCT state. These results demonstrate that BrRe(P⋯N)(N⋯P)ReBr preserves the dual emitting nature previously reported for the mononuclear complex RePNBr, with emission associated with and states.
authors.affiliation: Universidad Andres Bello, Facultad de Ciencias Exactas, Departamento de Ciencias Químicas. Quillota 980, Viña del Mar, Chile. andresvega@unab.cl.
authors.forename: Marianela
authors.initials: M
authors.lastname: Saldías
authors.affiliation: Universidad De Chile, Facultad de Ciencias Físicas y Matemáticas, Departamento de Ciencias de los Materiales, Av. Tupper 2460, Santiago, Chile.
authors.forename: Jorge
authors.initials: J
authors.lastname: Manzur
authors.affiliation: Universidad Nacional de Rio Cuarto y CONICET, Facultad de Ciencias Exactas Fisicoquímicas y Naturales, Departamento de Química, Campus Universitario, 5800 Río Cuarto, Córdoba, Argentina.
authors.forename: Rodrigo E
authors.initials: RE
authors.lastname: Palacios
authors.affiliation: Universidad Nacional de Rio Cuarto y CONICET, Facultad de Ciencias Exactas Fisicoquímicas y Naturales, Departamento de Química, Campus Universitario, 5800 Río Cuarto, Córdoba, Argentina.
authors.forename: María L
authors.identifier: http://orcid.org/0000-0002-3542-1038
authors.initials: ML
authors.lastname: Gómez
authors.affiliation: Universidad De Chile, Facultad de Ciencias Químicas y Farmacéuticas, Departamento de Química Orgánica y Fisicoquímica, Sergio Livingstone 1007, Santiago, Chile.
authors.forename: Julio De La
authors.initials: J
authors.lastname: Fuente
authors.affiliation: Universidad De Chile, Facultad de Ciencias Químicas y Farmacéuticas, Departamento de Química Orgánica y Fisicoquímica, Sergio Livingstone 1007, Santiago, Chile.
authors.forename: Germán
authors.initials: G
authors.lastname: Günther
authors.affiliation: Universidad Andres Bello, Facultad de Ciencias Exactas, Departamento de Ciencias Químicas. Quillota 980, Viña del Mar, Chile. andresvega@unab.cl.
authors.forename: Nancy
authors.initials: N
authors.lastname: Pizarro
authors.affiliation: Universidad Andres Bello, Facultad de Ciencias Exactas, Departamento de Ciencias Químicas. Quillota 980, Viña del Mar, Chile. andresvega@unab.cl and Centro para el Desarrollo de la Nanociencia y la Nanotecnología, CEDENNA, Chile.
authors.forename: Andrés
authors.identifier: http://orcid.org/0000-0001-6501-4161
authors.initials: A
authors.lastname: Vega