p-Quinquephenyl diamine, C6H5–p-C6H4–p-C6H2(2,3-NH2)–p-C6H4–C6H5, and its corresponding diimine–Ru(II) complex: Crystal structure and electrochemical and optical properties
                                
                                    
                                        作者:Take-aki Koizumi、Bong-Jin Choi、Takakazu Yamamoto                                    
                                    
                                        DOI:10.1016/j.ica.2007.10.036
                                    
                                    
                                        日期:2008.5
                                    
                                    The molecular structure of an o-phenylenediamine unit-containing oligophenylene (1), Ph-Ph'-Ph'(2,3-NH2)-Ph'-Ph (Ph = phenyl; Ph' = p-phenylene; Ph'(2,3-NH2) = 2,3-diamino-p-phenylene), was determined by X-ray crystallography. 1 has a twisted structure, and forms an intermolecular C-H center dot center dot center dot p interaction network. The-NH2 group of 1 was air-oxidized to an imine, =NH, group in the presence of [RuCl2(bpy)(2)] (bpy = 2,2'-bipyridyl) and gave a ruthenium(II)-benzoquinone diimine complex [Ru(2)(bpy)(2)](PF6)(2) (2: Ph-Ph'-Ph'(2,3-imine)-Ph'-Ph). The molecular structure of [Ru(2)(bpy)(2)](PF6)(2) was confirmed by X-ray crystallography. [Ru(2)(bpy)(2)](PF6)(2) underwent two-step electrochemical reduction with E-1/2 = -0.889 V and -1.531 V versus Fc(+)/Fc. The E(1/2,)s were located at higher potentials by 91 mV and 117 mV, respectively, than those of reported [Ru(bqdi)(bpy)(2)](PF6)(2) (bqdi = benzoquinone diimine). Electrochemical oxidation of [Ru(2)(bpy)(2)](PF6)(2) occurred at a lower potential by 180 mV than that of [Ru(bqdi)(bpy)(2)](PF6)(2). Occurrence of the easier reduction and oxidation of [Ru(2)(bpy)(2)](PF6)(2) than those of [Ru(bqdi)(bpy)(2)](PF6)(2) is ascribed to the presence of a large pi-conjugation system in 2. (C) 2007 Elsevier B.V. All rights reserved.