Polypyridyl ruthenium(II) complexes with tetrazolate-based chelating ligands. Synthesis, reactivity, and electrochemical and photophysical properties.
Polypyridyl ruthenium(II) complexes with tetrazolate-based chelating ligands. Synthesis, reactivity, and electrochemical and photophysical properties.
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DOI：
10.1021/ic7011556
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发表时间：
2007-09
影响因子：
4.6
通讯作者：
Stefano Stagni;E. Orselli;A. Palazzi;L. De Cola;S. Zacchini;C. Femoni;M. Marcaccio;F. Paolucci;S. Zanarini
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文献类型：
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作者：
Stefano Stagni;E. Orselli;A. Palazzi;L. De Cola;S. Zacchini;C. Femoni;M. Marcaccio;F. Paolucci;S. Zanarini
本文报道了两个单核配合物[Ru（bpy）2L]~+（bpy为2，2 '-bipyridine）的合成、化学和物理性质，以及对亲电试剂的反应性。其中L分别由2-（1，H-四唑-5-基）吡啶（L1）和2-（1，H-四唑-5-基）吡嗪（L2）的去质子化形式表示。对配合物RuL 1和RuL 2进行的1H和13 C NMR实验使我们能够确定四唑基部分通过N-1氮键合到金属中心，而配位配体在配位时采用的共面排列和随后的环间共轭效应解释了四唑碳的出乎意料的低场共振。13 C NMR光谱对于确定在五元环的N-3氮上向RuL 1和RuL 2加成甲基的化学选择性和区域选择性也具有根本重要性。所有这些特征都通过RuL 1和甲基化化合物RuL 1 Me和RuL 2 Me的X-射线衍射结构得到证实。相对于这些后者的配合物，甲基部分的存在下，不会引起任何变形从共面性的协调四唑。通过循环伏安法研究了配合物的氧化还原性质，结果表明吡嗪基四唑和吡啶基四唑配合物之间的行为完全不同，这是由于吡嗪环具有较高的吸电子特性。的配合物的物理性质的研究也显示了显着的差异之间的发光RuL 1和相当差的发射RuL 2。有趣的是，甲基化的化合物RuL 1 Me和RuL 2 Me显示出辐射激发态衰变，寿命比它们的前体更长;这一特征表明甲基化是一种有用的反应，用于调节类似四唑配合物的发光性能。本文还报道了一种新型双核配合物[（bpy）_2 Ru-L_3-Ru（bpy）_2]~（2+），Ru（L_3）Ru，其中L_3为双-2，3-（1，H-四唑-5-基）吡嗪衍生的双阴离子。
In this contribution, we report the synthesis, the chemical and photophysical characterization, and the study of the reactivity toward electrophiles of two mononuclear complexes of the type [Ru(bpy)2L]+ (bpy is 2,2'-bipyridyl), in which L is represented by the deprotonated form of 2-(1,H-tetrazol-5-yl)pyridine (L1) or 2-(1,H-tetrazol-5-yl)pyrazine (L2). The 1H and 13C NMR experiments that were performed on complexes RuL1 and RuL2 allowed us to establish that the tetrazolate moiety is bonded to the metal center via the N-1 nitrogen, while the coplanar arrangement adopted by the coordinated ligand upon coordination and the consequent interannular conjugation effect accounts for the unexpectedly low field resonance of the tetrazole carbon. The 13C NMR spectroscopy is also of fundamental importance to determine the chemo- and regioselectivity of the addition of a methyl group to RuL1 and RuL2, which takes place at the N-3 nitrogen of the five-membered ring. All these features were confirmed by the X-ray diffraction structures of RuL1 and of the methylated compounds RuL1Me and RuL2Me. Relative to these latter complexes, the presence of a methyl moiety does not cause any distortion from coplanarity of the coordinated tetrazolates. The redox properties of the complexes were investigated by cyclic voltammetry and indicated a quite different behavior between the pyrazinyl-tetrazolate and the pyridyl-tetrazolate complexes as the consequence of the higher electron-withdrawing character of the pyrazine ring. The study of the photophysical properties of the complexes also shows a significant diversity between the luminescent RuL1 and the rather poorly emissive RuL2. Interestingly, the methylated compounds RuL1Me and RuL2Me display radiative excited-state decays with longer lifetimes than their precursors; this feature indicates that methylation is a useful reaction for the tuning of the light emission performances of similar tetrazolate complexes. The synthesis and the characterization of a novel dinuclear complex of type [(bpy)2Ru-L3-Ru(bpy)2]2+, Ru(L3)Ru, where L3 is the bis-anion derived from bis-2,3-(1,H-tetrazol-5-yl)pyrazine, is also reported.