Byabartta Prithwiraj
Departmento de Quimica Inorganica, The Universidad de Zaragaza, Zaragaza, Spain.
Spectrochim Acta A Mol Biomol Spectrosc. 2007 Mar;66(3):521-33. doi: 10.1016/j.saa.2006.03.028. Epub 2006 Apr 6.
A facile reaction of cis-trans-cis-RuCl(2)(RaaiR')(2) [RaaiR'=1-alkyl-2-(arylazo)imidazole, m-R-C(6)H(4)-NN-C(3)H(2)-NN-1-R', where R=H (a), OMe (b), NO(2) (c) and R'=Me (1), Et (2) and CH(2)Ph (3)] either with 2,2'-bipyridine (bpy) and AgNO(3) followed by NaClO(4) or Ag(bpy)(2) in boiling acetone has isolated red-brown Ru(bpy)(RaaiR')(2)(2) (1a-c, 2a-c, 3a-c). The maximum molecular peak of Ru(bpy)(OMeaaiMe)(2)(2) (1b) is observed at m/z 888.01 (100%) in the FAB mass spectrum. IR spectra of the complexes show CN and NN stretching at 1590 and 1370cm(-1) which is red shifted by 40 and 90cm(-1) from the free ligand value supports Ru-azo nitrogen pi bonding interaction. The emission spectra in frozen glass (77K) are sharper and considerably more intense than the room temperature spectra. The (1)H NMR spectral measurements suggest methylene, -CH(2)-, in RaaiEt gives a complex AB type multiplet while in RaaiCH(2)Ph it shows AB type quartets. Considering two arylazoimidazole moieties there are 20 different carbon atoms in the molecule which gives a total of 20 different peaks in the (13)C NMR spectrum. In the (1)H-(1)H COSY spectrum of the present complexes, absence of any off-diagonal peaks extending from delta=14.12 and 9.55ppm confirm their assignment of no proton on N(1) and N(3), respectively. Contour peaks in the (1)H-(13)C HMQC spectrum in the present complexes, the absence of any contours at delta=147.12, 160.76, 155.67 and 157.68 ppm assign them to the C(2), C(6), C(8) and C(e and e'') carbon atoms, respectively. Cyclic voltammogram shows Ru(III)/Ru(II) redox couple along with three successive ligand reductions. The plot of difference in potential of first oxidation and reduction versus energy of main MLCT band (nu(CT)) is linear. Electrochemical parametrisation of Ru(III)/Ru(II) redox couple determines ligand potential E(L)(L).
顺 - 反 - 顺式RuCl₂(RaaiR')₂[RaaiR' = 1 - 烷基 - 2 - (芳基偶氮)咪唑，m - R - C₆H₄ - NN - C₃H₂ - NN - 1 - R'，其中R = H (a)、OMe (b)、NO₂ (c)且R' = Me (1)、Et (2)和CH₂Ph (3)]与2,2'-联吡啶(bpy)和AgNO₃反应，随后加入NaClO₄，或者在沸腾的丙酮中与Ag(bpy)₂反应，得到了红棕色的Ru(bpy)(RaaiR')₂₂(1a - c、2a - c、3a - c)。在快原子轰击质谱中，Ru(bpy)(OMeaaiMe)₂₂(1b)的最大分子峰出现在m/z 888.01 (100%)处。配合物的红外光谱显示，CN和NN伸缩振动分别在1590和1370cm⁻¹处，与游离配体值相比，分别红移了40和90cm⁻¹，这支持了Ru - 偶氮氮π键相互作用。在冷冻玻璃(77K)中的发射光谱比室温光谱更尖锐且强度大得多。¹H NMR光谱测量表明，在RaaiEt中的亚甲基 - CH₂ - 给出复杂的AB型多重峰，而在RaaiCH₂Ph中它显示AB型四重峰。考虑到两个芳基偶氮咪唑部分，分子中有20个不同的碳原子，这在¹³C NMR光谱中总共给出20个不同的峰。在本配合物的¹H - ¹H COSY光谱中，没有从δ = 14.12和9.55ppm延伸的任何非对角峰，分别证实了它们在N(1)和N(3)上没有质子的归属。在本配合物的¹H - ¹³C HMQC光谱中的等高线峰，在δ = 147.12、160.76、155.67和157.68ppm处没有任何等高线，分别将它们归属为C(2)、C(6)、C(8)和C(e和e'')碳原子。循环伏安图显示Ru(III)/Ru(II)氧化还原对以及三个连续的配体还原。第一次氧化和还原电位差与主要MLCT带能量(νCT)的关系图是线性的。Ru(III)/Ru(II)氧化还原对的电化学参数化确定了配体电位E(L)(L)。
