Organostannoxane‐Supported Multiferrocenyl Assemblies: Synthesis, Novel Supramolecular Structures, and Electrochemistry

Abstract

Organostannoxane-based multiredox assemblies containing ferrocenyl peripheries have been readily synthesized by a simple one-pot synthesis, either by a solution method or by room-temperature solid-state synthesis, in nearly quantitative yields. The number of ferrocenyl units in the multiredox assembly is readily varied by stoichiometric control as well as by the choice of the organotin precursors. Thus, the reaction of the diorganotin oxides, R2SnO (R = Ph, nBu and tBu) with ferrocene carboxylic acid affords tetra-, di-, and mononuclear derivatives [{Ph2Sn[OC(O)Fc]2}2] (1), [{[nBu2SnOC(O)Fc]2O}2] (2), [nBu2Sn{OC(O)Fc}2] (3), [{tBu2Sn(OH)OC(O)Fc}2] (4), and [tBu2Sn{OC(O)Fc}2] (5) (Fc = eta(5)C5H4-Fe-eta(5)C5H5). The reaction of triorganotin oxides, R3SnOSnR3 (R = nBu and Ph) with ferrocene carboxylic acid leads to the formation of the mono-nuclear derivatives [Ph3SnOC(O)Fc] (6) and [{nBu3SnOC(O)Fc}(n)] (7). Molecular structures of the compounds 1-4 and 6 have been determined by single-crystal X-ray analysis. The molecular structure of compound 1 is new among organotin carboxylates. In this compound, ferrocenyl carboxylates are involved in both chelating and bridging coordination modes to the tin atoms to form an eight-membered cyclic structure. In all of these compounds, the acidic protons of the cyclopentadienyl groups are hydrogen bonded to the carboxylate oxygens (C-HO) to form rich supramolecular assemblies. In addition to this, pi-pi, T-shaped, L-shaped, and side-to-face stacking interactions involving ferrocenyl groups also occur. Compound 6 shows an interesting and novel intermolecular CO2-pi stacking interaction. Electrochemical analysis of the compounds 1-4, 6, and 7 shows a single, quasi-reversible oxidation peak corresponding to the simultaneous oxidation of four, two, and one ferrocenyl substituents, respectively. Compound 5 shows two quasi-reversible oxidation peaks. This is attributed to the positional difference among the ferrocenyl substituents on the tin atom. Additionally, while compounds 2 and 4 are electrochemically quite robust and do not decompose even after ten continuous CV cycles, compounds 1, and 3, 5-7 start to show decomposition after five cycles.

Luminescence and Electrochemical Properties of Organostannoxane Coordination Polymer Based on Ferrocenyl-2-Cyano Carboxylate Ligand

“…The singlet at 8.58 ppm is due to aromatic proton. The 1 H NMR spectrum of ferrocenylorganostannoxane compared in litreature [13]. The 13 C NMR spectrum of the compound showed at 70.5 ppm is corresponding to the unsubstituted carbon of cyclopentadienyl ring in ferrocene moiety whereas substituted cyclopentadienyl ring carbon appears at 73.7 and 76.3 ppm, respectively.…”

“…The 1 H NMR spectrum of ferrocenylorganostannoxane compared in litreature [13]. The 13 C NMR spectrum of the compound showed at 70.5 ppm is corresponding to the unsubstituted carbon of cyclopentadienyl ring in ferrocene moiety whereas substituted cyclopentadienyl ring carbon appears at 73.7 and 76.3 ppm, respectively. Aliphatic CH3 appear 30.9 ppm and corresponding n-butyl (CH2-CH2-CH-) carbon appear at 128-137 ppm due to bulky organostannoxane.The nitrile group of (C≡N) appears at 117.5 ppm and carbonyl group appears at 207.0 ppm.…”

“…The compound was characterized by FT-IR, 1 H and 13 C NMR. It is further supported by absorbance spectra shows high-energy ligand-centred π-π * electronic transition and metal ligand charge transfer.…”

Multi-functional architectures supported on organostannoxane scaffolds

“…Utilizing this strategy other multi-ferrocene assemblies were prepared. 39 It is to be noted that the nuclearity of the organostannoxanes dictates the number of ferrocenes present in the peripheries (scheme 5).…”

“…This has been achieved in near quantitative yields (scheme 4). [38][39] These compounds represent inorganic-core supported multi-ferrocene assemblies. These are electrochemically quite robust and do not decompose under cyclic voltammetric conditions.…”