TY - JOUR
T1 - Osmium Bisterpyridine Complexes with Redox-Active Amine Substituents
T2 - A Comparison Study with Ruthenium Analogues
AU - Sun, Meng Jia
AU - Shao, Jiang Yang
AU - Yao, Chang Jiang
AU - Zhong, Yu Wu
AU - Yao, Jiannian
N1 - Publisher Copyright:
© 2015 American Chemical Society.
PY - 2015/8/17
Y1 - 2015/8/17
N2 - Five osmium complexes with redox-active amine substituents, [Os(ttpy)(Ntpy)](PF6)2 (1(PF6)2), [Os(Ntpy)2](PF6)2 (2(PF6)2), [Os(ttpy)(NPhtpy)](PF6)2 (3(PF6)2), [Os(Ntpy)(NPhtpy)](PF6)2 (4(PF6)2), and [Os(NPhtpy)2](PF6)2 (5(PF6)2), have been prepared, where ttpy is 4′-tolyl-2,2′:6′,2″-terpyridine, Ntpy is 4′-(di-p-anisylamino)-2,2′:6′,2″-terpyridine, and NPhtpy is 4′-(di-p-anisylaminophen-4-yl)-2,2′:6′,2″-terpyridine. X-ray crystallographic data of 2(PF6)2 and 4(PF6)2 are presented. These complexes show rich visible absorptions attributed to the singlet metal-to-ligand charge-transfer (1MLCT), triplet MLCT, and intraligand charge-transfer transitions. Complexes 3(PF6)2 and 5(PF6)2 show weak emissions around 720 nm at room temperature. All complexes show stepwise oxidations of the osmium ion and the amine segment. However, the redox potentials and the order of the OsIII/II and N•+/0 processes vary significantly, depending on the electronic nature of the amine substituents. In the singly oxidized state, either Os(II) → N•+ MLCT or N → Os(III) ligand-to-metal charge-transfer transitions in the near-infrared region have been observed. For complexes 2(PF6)2, 4(PF6)2, and 5(PF6)2 with two amine substituents, no evidence has been observed for the presence of osmium-mediated amine-amine electronic coupling. Density functional theory (DFT) and time-dependent DFT calculations have been performed to complement these experimental results. The one-electron-oxidized forms 33+ and 53+ show distinct electron paramagnetic resonance (EPR) signals in CH3CN at room temperature. However, complexes 13+, 23+, and 43+ are EPR silent under similar conditions. In addition, a comparison study has been made between these osmium complexes and the previously reported ruthenium analogues. (Chemical Equation Presented).
AB - Five osmium complexes with redox-active amine substituents, [Os(ttpy)(Ntpy)](PF6)2 (1(PF6)2), [Os(Ntpy)2](PF6)2 (2(PF6)2), [Os(ttpy)(NPhtpy)](PF6)2 (3(PF6)2), [Os(Ntpy)(NPhtpy)](PF6)2 (4(PF6)2), and [Os(NPhtpy)2](PF6)2 (5(PF6)2), have been prepared, where ttpy is 4′-tolyl-2,2′:6′,2″-terpyridine, Ntpy is 4′-(di-p-anisylamino)-2,2′:6′,2″-terpyridine, and NPhtpy is 4′-(di-p-anisylaminophen-4-yl)-2,2′:6′,2″-terpyridine. X-ray crystallographic data of 2(PF6)2 and 4(PF6)2 are presented. These complexes show rich visible absorptions attributed to the singlet metal-to-ligand charge-transfer (1MLCT), triplet MLCT, and intraligand charge-transfer transitions. Complexes 3(PF6)2 and 5(PF6)2 show weak emissions around 720 nm at room temperature. All complexes show stepwise oxidations of the osmium ion and the amine segment. However, the redox potentials and the order of the OsIII/II and N•+/0 processes vary significantly, depending on the electronic nature of the amine substituents. In the singly oxidized state, either Os(II) → N•+ MLCT or N → Os(III) ligand-to-metal charge-transfer transitions in the near-infrared region have been observed. For complexes 2(PF6)2, 4(PF6)2, and 5(PF6)2 with two amine substituents, no evidence has been observed for the presence of osmium-mediated amine-amine electronic coupling. Density functional theory (DFT) and time-dependent DFT calculations have been performed to complement these experimental results. The one-electron-oxidized forms 33+ and 53+ show distinct electron paramagnetic resonance (EPR) signals in CH3CN at room temperature. However, complexes 13+, 23+, and 43+ are EPR silent under similar conditions. In addition, a comparison study has been made between these osmium complexes and the previously reported ruthenium analogues. (Chemical Equation Presented).
UR - http://www.scopus.com/inward/record.url?scp=84939455003&partnerID=8YFLogxK
U2 - 10.1021/acs.inorgchem.5b01420
DO - 10.1021/acs.inorgchem.5b01420
M3 - Article
AN - SCOPUS:84939455003
SN - 0020-1669
VL - 54
SP - 8136
EP - 8147
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 16
ER -