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Salts of the ethynyl-closo-dodecaborate dianion [HC≡C-closo-B12H11]2– (1) were synthesized by a microwave-assisted palladium-catalyzed cross-coupling reaction starting from the iodinated cluster [I-closo-B12H11]2– and Me3SiC≡CMgBr. The dianion was characterized in its [nBu4N]+ and Cs+ salt by multi-NMR and vibrational spectroscopy as well as by (–)-MALDI mass spectrometry. A crystal of [nBu4N]2[HC≡C-closo-B12H11] was studied by X-ray diffraction. The experimental bond properties and the spectroscopic data are compared to values derived from density functional and (RI)-MP2 calculations. The charge distribution in the ethynyl substituents of the isoelectronic boron clusters 1, [12-HC≡C-closo-1-CB11H11]–,and 9-HC≡C-closo-1, 2-CB11H11 is compared. Furthermore, the crystal structure of the [nBu4N]+ salt of the intermediate[Me3SiC≡C-closo-B12H11]2– (2) is described. |
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