cis-Dicyanoosmium(II) Diimine Complexes Bearing Phosphine or Sulfoxide Ligands: Spectroscopic and Luminescent Studies
详细信息 查看全文
- 作者：Siu-Wai Lai ; Queenie K.-W. Chan ; Nianyong Zhu ; Chi-Ming Che
- 刊名：Inorganic Chemistry
- 出版年：2007
- 出版时间：December 24, 2007
- 年：2007
- 卷：46
- 期：26
- 页码：11003 - 11016
- 全文大小：550K
- 年卷期：v.46,no.26(December 24, 2007)
- ISSN：1520-510X
文摘
A series of cis-dicyanoosmium(II) complexes [Os(PPh3)2(CN)2(NN)] (NN = Ph2phen (2a), bpy (2b), phen (2c),Ph2bpy (2d), tBu2bpy (2e)) and [Os(DMSO)2(CN)2(NN)] (3a-3e, NN = Br2phen (3f), Clphen (3g)), were synthesizedand their spectroscopic and photophysical properties were examined, and [Os(PMe3)2(CN)2(phen)] (4) with axialPMe3 ligands was similarly prepared. The molecular structures of 2a, 2c, [2c·Zn(NO3)2], 2d, 2e, 3b, 3d, 3e, and4 were determined by X-ray crystallographic analyses. The two CN ligands are cis to each other with mean Os-Cbond distance of 2.0 Å. The two PR3 (R = Ph, Me) or DMSO ligands are trans to each other with P/S-Os-P/Sangles of ~177. The UV-vis absorption spectra of 2a-2e display an intense absorption band at 268-315 nm (= ~(1.54-4.82) × 104 M-1 cm-1) that are attributed to *(NN) and/or *(PPh3) transitions. Themoderately intense absorption bands with max at 387-460 nm ( = ~ (2.4-11.3) × 103 M-1 cm-1) are attributedto a 1MLCT transition. A weak, broad absorption at 487-600 nm ( = ~390-1900 M-1 cm-1) is assigned to a3MLCT transition. Excitation of 2a-2e in dichloromethane at 420 nm gives an emission with peak maximum at654-703 nm and lifetime of 0.16-0.67 s. The emission energies, lifetimes, and quantum yields show solvatochromicresponses, and plots of max, , and , respectively, versus ET (solvent polarity parameter) show linear correlations,indicating that the emission is sensitive to the local environment. The broad structureless solid-state emission of2a-2e at 298 (max 622-707 nm) and 77 (max 602-675 nm) K are assigned to 3MLCT excited states. The 77 KMeOH/EtOH (1:4) glassy solutions of 2a-2e also exhibit 3MLCT emissions with max = 560-585 nm. The 1MLCTabsorption and 3MLCT emission of 3a-3g occur at max = 332-390 nm and 553-644 nm, respectively. In thepresence of Zn(NO3)2, both the 1MLCT absorption and 3MLCT emission of 2c in acetonitrile blue-shift from 397 to341 nm and 651 to 531 nm, respectively. The enhancement of emission intensity (I/Io) of 2e at 531 nm reacheda maximum of ~810 upon the addition of two equivs of Zn(NO3)2. The crystallographic and spectroscopic evidencesuggests that 2c undergoes binding of Zn2+ ions via the cyano moieties.
© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号 地址：北京市海淀区学院路29号 邮编：100083 电话：办公室：(+86 10)66554848；文献借阅、咨询服务、科技查新：66554700 |