The [3,3′-Co(1,2-C2B9H11)2]– anion as a platform for new materials: synthesis of its functionalized monosubstituted derivatives incorporating synthons for conducting organic polymers
[3,3′-Co(8-C5H10O-1,2-C2B9H10)(1′,2′-C2B9H11)] (2) was synthesized by reaction of the caesium salt of [Co(C2B9H11)2]− with dimethyl sulfate in the presence of sulfuric acid as catalyst and tetrahydropyrane as solvent; the zwitterionic compound (2) yielded [3,3′-Co(8-C4H4N-(CH2)5-O-1,2-C2B9H10)(1′,2′-C2B9H11)]− (6), [3,3′-Co(8-C8H6N-(CH2)5-O-1,2-C2B9H10)(1′,2′-C2B9H11)]− (7), and [3,3′-Co(8-C12H8N-(CH2)5-O-1,2-C2B9H10)(1′,2′-C2B9H11)]− (8) through the nucleophilic addition of potassium pyrrolyl, indolyl and carbazolyl, respectively. The nucleophilic addition of the same salts on [3,3′-Co(8-C4H8O2-1,2-C2B9H10)(1′,2′-C2B9H11)] (1) yielded, respectively, [3,3′-Co(8-C4H4N-(CH2)2-O-(CH2)2-O-1,2-C2B9H10)(1′,2′-C2B9H11)]− (3), [3,3′-Co(8-C8H6N-(CH2)2-O-(CH2)2-O-1,2-C2B9H10)(1′,2′-C2B9H11)]− (4), and [3,3′-Co(8-C12H8N-(CH2)2-O-(CH2)2-O-1,2-C2B9H10)(1′,2′-C2B9H11)]− (5). All these products were isolated, purified and characterized by means of 1H, 1H{11B}, 11B, 11B{1H} and 13C{1H}-NMR and IR spectroscopies, MS MALDI-TOF spectrometry and elemental analysis. The behavior of the exo-cluster chain has been proven to be, in solution, very similar irrespective of the nucleophilic agent introduced into the molecule. The X-ray diffraction study of the potassium salt of 3 has proven the evidence of B–HK+ interactions in solid state. The 1H{11B}-NMR spectra recorded in the range between 37 °C and −58 °C have proven the presence of the three intramolecular B–HK+ interactions in solution. The possible role of [Co(C2B9H11)2]− as a doping agent in conducting organic polymers is also discussed.