Exploring Imidazole Binding Flexibility in 2D and 3D Frameworks Using Hypercoordinated Triorganotin Carboxylates Featuring a Nitrogen-Rich Ligand with Benzoic Acid, Diazenyl, and Imidazole Functionalities: Insights into Sn − N, N → Sn, and N − H⋅⋅⋅X (X = N, O) Interactions†

The multitopic heterofunctional pro-ligand 4-[(E)-(1H-imidazol-2-yl)diazenyl]benzoic acid (H′HL) was synthesized by diazotization of 4-aminobenzoic acid followed by coupling with imidazole. Reactions of H′HL (where H = imidazole proton and H′ = carboxylic acid proton) with the triorganotin precursors ⁿPr₃SnCl, (ⁿBu₃Sn)₂O and Ph₃SnOH provided three hypercoordinated triorganotin complexes, viz., [ⁿPr₃Sn(μ⁴-L)SnⁿPr₃]_n⋅1/8nEtOH (1), [ⁿBu₃Sn(μ-HL)]_n (2) and [Ph₃Sn(HL)]⋅0.5C₆H₆ (3), with complex 2D and 3D frameworks based on Sn − O, O → Sn, Sn − N and N → Sn metal–ligand bonds as well as N − H⋅⋅⋅N, N − H⋅⋅⋅O and π-interactions. The compositions and structures of 1–3 in solution and in the solid-state were unambiguously established by NMR (¹H, ¹³C, ¹¹⁹Sn) and IR spectroscopy, UV‒Vis spectral analysis, high-resolution mass spectrometry (HRMS) and single-crystal X-ray diffraction (scXRD) studies accompanied by Hirshfeld surface maps and 2D fingerprint plots. The binding potential of a heterotopic ligand carrying strong metal-coordinating carboxylate and imidazole functions and a color-providing diazenyl group, all embedded in an overall planar skeleton, was examined in 1:1 and 1:2 combinations with triorganotin moieties, yielding the frameworks illustrated in the graphical abstract. [ABSTRACT FROM AUTHOR]