Azo-anilido complexes of ruthenium(IV) and osmium(IV): Syntheses, characterization, electronic spectra and electron transfer properties

IF 2.4 3区化学 Q2 CHEMISTRY, INORGANIC & NUCLEAR

Polyhedron Pub Date : 2025-07-04 DOI:10.1016/j.poly.2025.117661

Jahar Lal Pratihar

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Abstract

The reaction of 2-(arylazo) aniline, (HL) [where HL is 2-(ArNN)C₆H₄NH₂; Ar = C₆H₅(for HL¹) and p-ClC₆H₄(for HL²) H represents the amino protons], with Ru(PPh₃)₃Cl₂ and (NH₄)₂OsBr₆ separately afforded the new tetravalent azo-anilido complexes Ru(L¹)₂Cl₂ (1) and Os(L²)₂Br₂ (2), respectively. Both the species Ru(L¹)₂Cl₂ (1) and Os(L²)₂Br₂ (2) were characterized by spectroscopic techniques and confirmed by x-ray structure determination. The azo-anilido chelate is six-membered; the phenyl ring adjacent to the chelate rings is distorted with four longer and two shorter bonds. This structural feature has been attributed to the delocalization of negative charge of the anionic ligands that formed in situ from the precursor (L⁻) due to dissociation of an amino proton. The ¹H NMR spectrum of (L¹)₂RuCl₂ confirms the low spin (S = 0) Ru(IV). Complexes 1 and 2 exhibited quasi-reversible reductive responses at −0.05 V, and −0.02 V respectively, vs. SCE. Both the complexes Ru(L¹)₂Cl₂ and Os(L²)₂Br₂ shows intense MLCT transitions in the visible region. The nature of the electronic spectra and electron transfer properties of both the complexes were rationalized employing DFT computation.

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钌（IV）和锇（IV）偶氮-苯胺配合物：合成、表征、电子能谱和电子转移性质

2-（芳偶氮）苯胺的反应，（HL）[其中HL为2-(ArNN)C6H4NH2；Ar = C6H5（对于HL1）和p-ClC6H4（对于HL2） H代表氨基质子]，Ru(PPh3)3Cl2和（NH4）2OsBr6分别生成新的四价偶氮-苯胺配合物Ru(L1)2Cl2(1)和Os(L2)2Br2(2)。Ru(L1)2Cl2(1)和Os(L2)2Br2(2)用光谱技术进行了表征，并通过x射线结构测定进行了证实。偶氮-苯胺螯合物是六元的；与螯合环相邻的苯基环被扭曲成四个较长的和两个较短的键。这种结构特征归因于阴离子配体的负电荷的离域，这些负电荷是由于氨基质子的解离而从前体（L−）原位形成的。（L1）2RuCl2的1H NMR谱证实了低自旋（S = 0） Ru（IV）。与SCE相比，配合物1和2分别在- 0.05 V和- 0.02 V下表现出准可逆的还原反应。配合物Ru(L1)2Cl2和Os(L2)2Br2在可见光区均表现出强烈的MLCT跃迁。利用DFT计算对这两种配合物的电子能谱性质和电子转移性质进行了理顺。

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来源期刊

Polyhedron 化学-晶体学

CiteScore

4.90

自引率

7.70%

发文量

515

审稿时长

2 months

期刊介绍： Polyhedron publishes original, fundamental, experimental and theoretical work of the highest quality in all the major areas of inorganic chemistry. This includes synthetic chemistry, coordination chemistry, organometallic chemistry, bioinorganic chemistry, and solid-state and materials chemistry. Papers should be significant pieces of work, and all new compounds must be appropriately characterized. The inclusion of single-crystal X-ray structural data is strongly encouraged, but papers reporting only the X-ray structure determination of a single compound will usually not be considered. Papers on solid-state or materials chemistry will be expected to have a significant molecular chemistry component (such as the synthesis and characterization of the molecular precursors and/or a systematic study of the use of different precursors or reaction conditions) or demonstrate a cutting-edge application (for example inorganic materials for energy applications). Papers dealing only with stability constants are not considered.