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

This article dealt with the ruthenium and osmium derivatives of isomeric 1-indazole-3-carboxylic acid/2-indazole-3-carboxylic acid (HL1) and 1-benzimidazole-2-carboxylic acid (HL2) along with the π-acidic bpy (bpy = 2,2'-bipyridine) and pap (pap = 2-phenylazopyridine) co-ligands. It thus extended structurally authenticated monomeric ([(bpy)Ru(HL1)]ClO []ClO, (pap)Ru(L1) , (bpy)Os(L1) , (pap)Os(L1) , (bpy)Ru(L2) , (bpy)Os(L2) , and (pap)Os(L2) ) and dimeric ((bpy)Ru(μ-L2)Ru(bpy) ) complexes. It also described modified L2' (L2' = 2,2'-bisbenzimidazolate)-bridged (pap)Ru(μ-L2')Ru(pap) , where L2' was developed selectively with the {Ru(pap)} metal fragment via in situ intermolecular C-C coupling of the two units of decarboxylated benzimidazolate. Moreover, chemical oxidation (Os to Os) of (bpy)Os(L1) ( = 0.11 V versus SCE) and (bpy)Os(L2) ( = 0.12 V versus SCE) by AgClO yielded unprecedented Os-Ag derived polymeric {(bpy)Os-L1-Ag(CHCN)} {} and dimeric (bpy)Os-L2-Ag(CHCN) complexes as a function of and orientations of the active N2 donor with special reference to the carboxylate O2 of L, respectively. Microscopic (FE-SEM, TEM-EDX, and AFM) and DLS experiments suggested a homogeneously dispersed hollow spherical shaped morphology of {} 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 in the present coordination situations and the selective anion sensing (X = F, CN, and OAc) event of []ClO involving a free NH group at the backface of HL1, which proceeded via the NH···X hydrogen bonding interaction.