TY - JOUR
T1 - Excited-state properties of octahedral hexarhenium(lll) complexes with redox-active N-heteroaromatic ligands
AU - Yoshimura, Takashi
AU - Suo, Chiaki
AU - Tsuge, Kiyoshi
AU - Ishizaka, Shoji
AU - Nozaki, Koichi
AU - Sasaki, Yoichi
AU - Kitamura, Noboru
AU - Shinohara, Atsushi
PY - 2010/1/18
Y1 - 2010/1/18
N2 - New sulflde-capped octahedral hexarhenium(lll) complexes containing 4-phenylpyridine (ppy) or 1,2-bis(4-pyridyl)ethane (bpe) ((n-C4H 9)4N)[mer-{Re6S8Cl 3(ppy)3}] ((Bu4N)[1]), ((n-C4H 9)4N)2[trans-{Re6S 8Cl4(ppy)2}] ((Bu4N) 2[2a]), ((n-C4H9)4N) 2[cis-{Re6S8Cl4(ppy)2}] ((Bu4N)2[2b]), ((n-C4H9) 4N)2[trans-{Re6S8Cl 4(bpe)2}] ((Bu4N)2[3a]), and ((n-C4H9)4N)2[cis-{Re 6S8Cl4(bpe)2}] ((Bu 4N)2[3b]) were prepared, and X-ray single-crystal structure determination was carried out for (Bu4N)2[2a] and (Bu4N)2[3a]. The photophysical properties of these complexes were studied both in acetonitrile at 298 K and in the solid state at 298 and 80 K, along with those of the known 4,4'-bipyridine (bpy) analogues ((n-C4H9)4N)[mer-{Re6S 8Cl3(bpy)3}] ((Bu4N)[4]), ((n-C 4H9)4N)2-[trans-{Re 6S8Cl4(bpy)2}] ((Bu 4N)2[5a]), and ((n-C4H9) 4N)2[cis-{Re6S8Cl 4(bpy)2}] ((Bu4N)2[5b]). The photophysical data of [5a]2- and [5b]2- in solution and in the solid state were significantly different from those of other complexes. On the basis of experimental observations of [2a]2- and [5a] 2- and density-functional theory (DFT) calculations, It was concluded that [5a]2- and [5b]2- exhibited metal (Re 6S8 core)-to-ligand (bpy) charge transfer (MLCT) type emission. This Is the first unambiguous demonstration of MLCT type emissions for the hexarhenium complexes. The MLCT components, where present, are only minor in the case of the emissions of [1]-, [2a]2-, [2b] , and [4]-; these can be explained primarily as the contributions of the intracore electronic transitions. The emissions of [3a]2- and [3b]2- can be assigned almost completely to the electronic transitions within the Re6S8 core. The different emission characteristics of the bis(bpy) complexes ([5a]2- and [5b] 2-) from the tris(bpy) complex ([4]-) are a result of the increase in the number of nitrogen donors on the Re6S8 core, which stabilizes the Re6S8 core energy to a lower level than the energy of the bpy ligand π* orbital. On the other hand, it has been shown that the emissions of the bis(ppy) ([2a]2- and [2b]2-) and bis(bpe) complexes ([3a]2- and [3b] 2-) are best characterized by the higher π* energy level of each N-heteroaromatic ligand, which lead to a stronger metal character In the emissive excited state of the complex.
AB - New sulflde-capped octahedral hexarhenium(lll) complexes containing 4-phenylpyridine (ppy) or 1,2-bis(4-pyridyl)ethane (bpe) ((n-C4H 9)4N)[mer-{Re6S8Cl 3(ppy)3}] ((Bu4N)[1]), ((n-C4H 9)4N)2[trans-{Re6S 8Cl4(ppy)2}] ((Bu4N) 2[2a]), ((n-C4H9)4N) 2[cis-{Re6S8Cl4(ppy)2}] ((Bu4N)2[2b]), ((n-C4H9) 4N)2[trans-{Re6S8Cl 4(bpe)2}] ((Bu4N)2[3a]), and ((n-C4H9)4N)2[cis-{Re 6S8Cl4(bpe)2}] ((Bu 4N)2[3b]) were prepared, and X-ray single-crystal structure determination was carried out for (Bu4N)2[2a] and (Bu4N)2[3a]. The photophysical properties of these complexes were studied both in acetonitrile at 298 K and in the solid state at 298 and 80 K, along with those of the known 4,4'-bipyridine (bpy) analogues ((n-C4H9)4N)[mer-{Re6S 8Cl3(bpy)3}] ((Bu4N)[4]), ((n-C 4H9)4N)2-[trans-{Re 6S8Cl4(bpy)2}] ((Bu 4N)2[5a]), and ((n-C4H9) 4N)2[cis-{Re6S8Cl 4(bpy)2}] ((Bu4N)2[5b]). The photophysical data of [5a]2- and [5b]2- in solution and in the solid state were significantly different from those of other complexes. On the basis of experimental observations of [2a]2- and [5a] 2- and density-functional theory (DFT) calculations, It was concluded that [5a]2- and [5b]2- exhibited metal (Re 6S8 core)-to-ligand (bpy) charge transfer (MLCT) type emission. This Is the first unambiguous demonstration of MLCT type emissions for the hexarhenium complexes. The MLCT components, where present, are only minor in the case of the emissions of [1]-, [2a]2-, [2b] , and [4]-; these can be explained primarily as the contributions of the intracore electronic transitions. The emissions of [3a]2- and [3b]2- can be assigned almost completely to the electronic transitions within the Re6S8 core. The different emission characteristics of the bis(bpy) complexes ([5a]2- and [5b] 2-) from the tris(bpy) complex ([4]-) are a result of the increase in the number of nitrogen donors on the Re6S8 core, which stabilizes the Re6S8 core energy to a lower level than the energy of the bpy ligand π* orbital. On the other hand, it has been shown that the emissions of the bis(ppy) ([2a]2- and [2b]2-) and bis(bpe) complexes ([3a]2- and [3b] 2-) are best characterized by the higher π* energy level of each N-heteroaromatic ligand, which lead to a stronger metal character In the emissive excited state of the complex.
UR - http://www.scopus.com/inward/record.url?scp=74549180993&partnerID=8YFLogxK
U2 - 10.1021/ic9015788
DO - 10.1021/ic9015788
M3 - 学術論文
C2 - 20000831
AN - SCOPUS:74549180993
SN - 0020-1669
VL - 49
SP - 531
EP - 540
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 2
ER -