Synthesis, Ethanolysis, and Hydrolysis of Bismuth(III) ortho-Nitrobenzoate Complexes en Route to a Pearl Necklace-like Polymer of Bi₁₀ Oxo-Clusters

Abstract

In exploring the formation of heteroleptic bismuth benzoates and their conversion to polynuclear bismuth oxo-clusters through hydrolysis, ortho-nitrobenzoic acid (= LH) was treated with triphenylbismuth under various reaction conditions. The simple 2:1 stoichiometric reaction in ethanol produced four crystalline products; [{BiL 2 (OEt)(EtOH)} 2 ] ¥ (2) and [Ph 2 BiL] ¥ (4) initially crystallized together, while [BiL 3 (H 2 O)] ¥ (1) appeared later from the filtered mother liquor. Compound 2 results from the in situ ethanolysis of [PhBiL 2 ] n (3) and subsequently undergoes hydrolysis to give crystals of the Bi 10 oxo-cluster [Bi 10 O 8 L 14 (EtOH) x .(EtOH) y (H 2 O) z ] ¥ (5). This latter process was confirmed through the formation of the moisture-sensitive compound [PhBiL 2 ] n under solvent-free, inert atmosphere conditions, which on treatment with dry ethanol produced [{BiL 2 (OEt)(EtOH)} 2 ] ¥ (2). Compound 4 was obtained as a single isolable product from the 1:1 reaction of o-(NO 2 )-C 6 H 4 CO 2 H with BiPh 3 in diethyl ether at room temperature. Single-crystal X-ray diffraction studies on four of the five compounds (1, 2, 4, and 5) show them all to be polymeric in the solid state, having distinct coordination modes and methods of polymer formation. Complexes 1, 4, and 2 are carboxylate-bridged (1, 4) or carboxylate-and ethoxide-bridged (2) polymers in which Bi is nine, eight, and five (with additional Bi-π(Ar) interactions) coordinate respectively. In 5, Bi 10 O 8 L 14 cluster units are linked in a pearl necklace motif by bridging carboxylate groups. These oxo-clusters have a distorted rhombic dodecahedral Bi 6 O 8 core with four additional Bi atoms sited above alternate oxygen atoms.

Anti-Leishmanial activity of homo- and heteroleptic bismuth(III) carboxylates

“…Bi(III) alone is not responsible for high toxicity, evidenced by the NSAID complexes and the inorganic compounds. That the ligand plays a role in moderating the toxicity is also clear from the difference in toxicity observed between the NSAID complexes (10-13) and the substituted benzoates (17)(18)(19)(20)(21). So the low IC 50 numbers of the Bi(III) complexes in this study suggest that such bismuth compounds are good candidates for killing L. major promastigotes, however, their highly toxic behaviour against human fibroblasts makes them unsuitable candidates for treating Leishmaniasis.…”

“…Using a method similar to that which previously allowed us to synthesise and characterise [PhBi(o-NO 2 C 6 H 4 CO 2 ) 2 ] (18) [17], the heteroleptic bis-carboxylato complexes 19, 20 and 21, derived from omethoxybenzoic acid (5), m-methoxybenzoic acid (6), and 5-[(R/S)-2,3-dihydroxypropyl carbamoyl]-2-pyridine carboxylic acid (9) were synthesised by the reaction of the substituted benzoic acid with BiPh 3 in a 2:1 ratio under reflux in either methanol or ethanol (Table 1).…”

Synthesis and structural studies of the simplest bismuth(iii) oxo-salicylate complex: [Bi4(μ3-O)2(HO-2-C6H4CO2)8]·2Solv (Solv = MeCN or MeNO2)

“…These distances are similar to the other known bismuth carboxylates. [24][25][26] The solvent to Bi distances are long (3.06(2) Å) for MeCN and 3.103(4) for MeNO 2 ) but the solvents are clearly oriented so that they interact, albeit weakly, with the metal center. We expect the Bi 4 O 2 core will prove to be the simplest bismuth oxo salicylate.…”

Bismuth–ferrocene carboxylates: synthesis and structure

“…Another interesting feature of 2 is the absence of the (BiO) 2 core which is generally present in bismuth carboxylate coordination polymers. 13 Compound 3, unlike 1 and 2 is a molecular dinuclear complex that has co-crystallized with two ferrocenecarboxylic acid molecules. Each bismuth is bound to three ferrocene carboxylate ligands; of these, two function as chelating anisobidentate ligands.…”