Metallacarboranes as an anion and a cation in a single species: a unique example for ion pairs

Abstract

The reaction of closo- exo-5,6-Na(THF) 2-1-Na(THF) 2-2,4-(SiMe 3) 2-2,4-C 2B 4H 4 ( 1) with anhydrous NdCl 3, in a molar ratio of 2:1, produced the full-sandwiched neodymacarborane, 2,2 ′,4,4 ′-(SiMe 3) 4-5,6-[(μ-H) 2Na(THF) 2]-1,1 ′- commo-Nd(η 5-2,4-C 2B 4H 4) 2 ( 2), as a yellow-green crystalline solid in 80% yield. Compound 2 was further reacted with NdCl 3, in 3:1 molar ratio, in a solvent mixture of dry benzene and THF to produce, in 75% yield, the novel dimeric ion-pair, {[ closo-1-Nd(μ-H) 6-2,4-(SiMe 3) 2-2,4-C 2B 4H 4] +[1,1 ′-(THF) 2-2,2 ′,4,4 ′-(SiMe 3) 4-5,5 ′,6,6 ′-(μ-H) 4-1,1 ′- commo-Nd(η 5-2,4-C 2B 4H 4)] −(C 4H 8O)(C 6H 6) 2} 2 ( 3), consisting of a half-sandwich cationic neodymacarborane that is coordinated to anionic full-sandwiched neodymacarborane. Thus, a dual role of metallacarboranes as both the cation and the anion in a single species has been exemplified.