Synthesis and characterization of new dicarbollide complexes

Abstract

The reaction of $Tl_2C_2B_9H_{11}$ with triphenyl phosphine in the presence of AgBr in dichloromethane generates the charge-compensated neutral carborane compound where triphenyl phosphine is attached to the boron next to carbon via oxidative coupling reaction. A single crystal X-ray structural determination was carried out on this compound. The $^{11}$B-NMR study revealed the existence of coupling between boron and phosphorous. The coupling constant was calculated to be 151 Hz. Thallium dicarbollide complex which had an intermolecular thallium-thallium interaction in crystal solid state was isolated and characterized by single X-ray diffraction studies. The $^{11}$B-NMR spectroscopic study on this compound showed the existance of $^{205}$Tl-${11}$B spin-spin coupling. The thallium ion is magnetically coupled to the three borons on the upper belt of dicarbollide ligand:ca 900 Hz coupling with the unique boron and 470 Hz coupling with the two symmetrical borons. The metal-metal interaction, along with the $^{205}$Tl-$^{11}$B coupling, supports a description for the metal-dicarbollide bonding interaction which is not completely ionic, as was originally believed.