Unique Metal-Ligand Interplay in Directing Discrete and Polymeric Derivatives of Isomeric Azole-Carboxylate. Varying Electronic Form, C-C Coupling, and Receptor Feature

Maya Kumari; Souradip Dasgupta; Sanjib Panda; Sudip Kumar Bera; Anindya Datta; Goutam Kumar Lahiri

doi:10.1021/acs.inorgchem.3c00418

Unique Metal-Ligand Interplay in Directing Discrete and Polymeric Derivatives of Isomeric Azole-Carboxylate. Varying Electronic Form, C-C Coupling, and Receptor Feature

Inorg Chem. 2023 May 22;62(20):7779-7794. doi: 10.1021/acs.inorgchem.3c00418. Epub 2023 May 10.

Authors

Maya Kumari¹, Souradip Dasgupta¹, Sanjib Panda¹, Sudip Kumar Bera¹, Anindya Datta¹, Goutam Kumar Lahiri¹

Affiliation

¹ Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.

PMID: 37163348
DOI: 10.1021/acs.inorgchem.3c00418

Abstract

This article dealt with the ruthenium and osmium derivatives of isomeric 1H-indazole-3-carboxylic acid/2H-indazole-3-carboxylic acid (H₂L1) and 1H-benzimidazole-2-carboxylic acid (H₂L2) along with the π-acidic bpy (bpy = 2,2'-bipyridine) and pap (pap = 2-phenylazopyridine) co-ligands. It thus extended structurally authenticated monomeric ([(bpy)₂Ru^II(HL1^-)]ClO₄ [1]ClO₄, (pap)₂Ru^II(L1^2-) 2, (bpy)₂Os^II(L1^2-) 3, (pap)₂Os^II(L1^2-) 4, (bpy)₂Ru^II(L2^2-) 5, (bpy)₂Os^II(L2^2-) 8, and (pap)₂Os^II(L2^2-) 9) and dimeric ([(bpy)₂Ru^II(μ-L2^2-)Ru^II(bpy)₂](ClO₄)₂ [6](ClO₄)₂) complexes. It also described modified L2'^2- (L2'^2- = 2,2'-bisbenzimidazolate)-bridged [(pap)₂Ru^II(μ-L2'^2-)Ru^II(pap)₂](ClO₄)₂ [7](ClO₄)₂, where L2'^2- was developed selectively with the {Ru(pap)₂} metal fragment via in situ intermolecular C-C coupling of the two units of decarboxylated benzimidazolate. Moreover, chemical oxidation (Os^II to Os^III) of (bpy)₂Os^II(L1^2-) 3 (E⁰ = 0.11 V versus SCE) and (bpy)₂Os^II(L2^2-) 8 (E⁰ = 0.12 V versus SCE) by AgClO₄ yielded unprecedented Os^III-Ag^I derived polymeric {[(bpy)₂Os^III-L1^2--Ag^I(CH₃CN)](ClO₄)₂}_n {[10](ClO₄)₂}_n and dimeric [(bpy)₂Os^III-L2^2--Ag^I(CH₃CN)](ClO₄)₂ [11](ClO₄)₂ complexes as a function of trans and cis orientations of the active N2 donor with special reference to the carboxylate O2 of L^2-, respectively. Microscopic (FE-SEM, TEM-EDX, and AFM) and DLS experiments suggested a homogeneously dispersed hollow spherical shaped morphology of {[10](ClO₄)₂}_n with an average particle size of 200-400 nm as well as its non-dissociative feature in the aprotic medium. Experimental (structure, spectroscopy, and electrochemistry) and theoretical (DFT/TD-DFT) explorations revealed a redox non-innocent feature of L^2- in the present coordination situations and the selective anion sensing (X = F^-, CN^-, and OAc^-) event of [1]ClO₄ involving a free NH group at the backface of HL1^-, which proceeded via the NH···X hydrogen bonding interaction.