Cobalt complexes of redox noninnocent azo-aromatic pincers. Isolation, characterization, and application as catalysts for the synthesis of quinazolin-4(3H)-ones.,Dalton Transactions

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Cobalt complexes of redox noninnocent azo-aromatic pincers. Isolation, characterization, and application as catalysts for the synthesis of quinazolin-4(3H)-ones.
Dalton Transactions ( IF 3.5 ) Pub Date : 2020-03-04 , DOI: 10.1039/d0dt00394h
Suman Sinha ₁ , Siuli Das , Rakesh Mondal , Sutanuva Mandal , Nanda D Paul

Affiliation

Herein we report the synthesis, characterization and catalytic application of three new cobalt(II)-complexes of redox noninnocent arylazo ligands, 2-(phenylazo)-1,10-phenanthroline (L^1a), 2-(4-chlorophenylazo)-1,10-phenanthroline (L^1b) and 2,9-bis(phenyldiazo)-1,10-phenanthroline (L²) respectively. The reaction of L^1a with Co^IICl₂·6H₂O produced a μ-dichloro bridged binuclear cobalt(II)-complex [Co^II₂(L^1a)₂Cl₂] (1a) while the same reaction when carried out with 2-(4-chlorophenyl)azo-1,10-phenanthroline (L^1b) and 2,9-bis(phenyldiazo)-1,10-phenanthroline (L²) ligands produced two new mononuclear five-coordinate cobalt(II)-complexes 1b and 2 respectively. In complex 1a and 1b, the ligands L^1a and L^1b are coordinated to the cobalt(II)-center in a tridentate mode utilizing all of its nitrogen donor sites while in complex 2 one of the azo-donor sites of the ligand L² remain pendant. All these complexes were characterized using available spectroscopic techniques and DFT studies. We further explored the potential of these complexes as catalysts for the synthesis of pharmaceutically important organic compounds via the functionalization of alcohols. A variety of substituted quinazolin-4(3H)-ones were synthesized under aerobic conditions via the coupling of alcohols and 2-aminobenzamide using 1b as the catalyst. Mechanistic investigations revealed that both cobalt and the arylazo scaffold act synergistically during catalysis.

中文翻译：

氧化还原非纯偶氮芳族钳的钴配合物。分离，表征和用作合成喹唑啉-4（3H）-one的催化剂。

在这里我们报告了氧化还原非纯芳基偶氮配体2-（苯基偶氮）-1,10-菲咯啉（L ^1a），2-（4-氯苯基偶氮）-1的三种新型钴（II）配合物的合成，表征和催化应用分别是，10-菲咯啉（L ^1b）和2,9-双（苯基重氮）-1，10-菲咯啉（L ²）。的反应大号^1A用Co ^II氯₂ ·6H ₂ O产生一个μ二氯桥接的双核钴（II） -配合物[CO ^II₂（大号^1A）₂氯₂ ]（1a中），而与2-（4-氯苯基）偶氮-1,10-菲咯啉（L ^1b）和2,9-双（苯基重氮）-1,10-菲咯啉（L ²）配体进行相同反应时，会产生两个新的单核五配位钴（II）配合物1b和2。在配合物1a和1b中，配体L ^1a和L ^1b利用其所有氮供体位点以三齿模式配位到钴（II）中心，而在配合物2中，配体L ²的偶氮供体位点之一保持吊坠。使用可用的光谱技术和DFT研究对所有这些复合物进行了表征。我们进一步探讨了这些配合物作为通过醇官能化合成重要的有机化合物的催化剂的潜力。在好氧条件下，通过醇和2-氨基苯甲酰胺的偶联，使用1b作为催化剂，合成了多种取代的喹唑啉-4（3 H）-1 。机理研究表明，钴和芳基偶氮支架在催化过程中均协同作用。

更新日期：2020-03-04

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