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

• Published in: Inorganic chemistry Vol. 62; no. 20; pp. 7779 - 7794
• Main Authors: Kumari, Maya, Dasgupta, Souradip, Panda, Sanjib, Bera, Sudip Kumar, Datta, Anindya, Lahiri, Goutam Kumar
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 22-05-2023
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.3c00418

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)2RuII(HL1–)]­ClO4 [1]­ClO4, (pap)2RuII(L12–) 2, (bpy)2OsII(L12–) 3, (pap)2OsII(L12–) 4, (bpy)2RuII(L22–) 5, (bpy)2OsII(L22–) 8, and (pap)2OsII(L22–) 9) and dimeric ([(bpy)2RuII(μ-L22–)­RuII(bpy)2]­(ClO4)2 [6]­(ClO4)2) complexes. It also described modified L2′2– (L2′2– = 2,2′-bisbenzimidazolate)-bridged [(pap)2RuII(μ-L2′2–)­RuII(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 (OsII to OsIII) of (bpy)2OsII(L12–) 3 (E 0 = 0.11 V versus SCE) and (bpy)2OsII(L22–) 8 (E 0 = 0.12 V versus SCE) by AgClO4 yielded unprecedented OsIII-AgI derived polymeric {[(bpy)2OsIII-L12–-AgI(CH3CN)]­(ClO4)2} n {[10]­(ClO4)2} n and dimeric [(bpy)2OsIII-L22–-AgI(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 L2–, 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 L2– 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.