A spectroscopic, electrochemical and structural study of polarizable, dipolar ruthenium(II) arsine complexes as models for chromophores with large quadratic non-linear optical responses
作者:Benjamin J. Coe、Tim Beyer、John C. Jeffery、Simon J. Coles、Thomas Gelbrich、Michael B. Hursthouse、Mark E. Light
DOI:10.1039/a909336b
日期:——
The new series of complex salts trans-[RuIICl(pdma)2L][PF6]2 [pdma = 1,2-phenylenebis(dimethylarsine); L = N-methyl-4,4′-bipyridinium (MeQ+) 2, N-phenyl-4,4′-bipyridinium (PhQ+) 3, N-(4-acetylphenyl)-4,4′-bipyridinium (4-AcPhQ+) 4, N-(2,4-dinitrophenyl)-4,4′-bipyridinium (2,4-DNPhQ+) 5 or N-(2-pyrimidyl)-4,4′-bipyridinium (2-PymQ+) 6] have been prepared. The known complex salt trans-[RuIICl(pdma)2(4,4′-bpy)]PF6 (4,4′-bpy = 4,4′-bipyridine) 1 exhibits an intense dπ(RuII)→π*(4,4′-bpy) metal-to-ligand charge-transfer (MLCT) absorption with λmax at 418 nm in acetonitrile, whilst 2–6 display dπ(RuII)→π*(L) MLCT bands with λmax values in the region 486–544 nm. The MLCT energy decreases as the electron-accepting ability of L increases, in the order L = MeQ+ < PhQ+ < 4-AcPhQ+ < 2,4-DNPhQ+ < 2-PymQ+. Cyclic voltammetric studies show that within the series 2–6, the energy of the Ru-based HOMO is almost constant, whilst that of the L-based LUMO decreases by ca. 0.4 eV moving from 2 to 6. Single-crystal structures of the complete series 1·DMF, 2, 3·MeCN, 4·Me2CO, 5·MeCN and 6 have been determined. Analysis of bond lengths and dihedral angles provides no evidence for ground state charge-transfer, despite the strongly dipolar, polarizable nature of these complexes.
新系列复盐反式-[RuIICl(pdma)2L][PF6]2 [pdma = 1,2-亚苯基双(二甲基
砷);L = N-甲基-4,4′-联
吡啶鎓(MeQ+)2,N-苯基-4,4′-联
吡啶鎓(PhQ+)3,N-(4-
乙酰苯基)-4,4′-联
吡啶鎓(4-AcPhQ+)4、制备了 N-(2,4-
二硝基苯基)-4,4′-联
吡啶鎓(
2,4-DNPhQ+)5 或 N-(2-
嘧啶基)-4,4′-联
吡啶鎓(2-PymQ+)6]。已知的复盐反式-[RuIICl(
钯)2(4,4′-bpy)]PF6(4,4′-bpy = 4,4′-联
吡啶)1 显示出强烈的 dπ(RuII)→π*(4、4′-bpy)
金属-
配体电荷转移(MLCT)吸收,在
乙腈中的 λmax 值为 418 nm,而 2-6 则显示出 dπ(RuII)→π*(L)MLCT 带,λmax 值在 486-544 nm 区域。MLCT 能量随着 L 的电子接受能力的增加而降低,顺序为 L = MeQ+ < PhQ+ < 4-AcPhQ+ < 2,4-DNPhQ+ < 2-PymQ+。循环伏安研究表明,在 2-6 系列中,Ru 基 HOMO 的能量几乎保持不变,而 L 基 LUMO 的能量则从 2 到 6 降低了约 0.4 eV。我们已经确定了完整系列 1-
DMF、2、3-MeCN、4-Me2CO、5-MeCN 和 6 的单晶结构。尽管这些复合物具有很强的双极性和可极化性,但对键长和二面角的分析没有提供基态电荷转移的证据。