Unique chemical properties of metal-carbon bonds in metal-carboranyl and metal-carboryne complexes

Abstract

The metal-carbon bonds in metal-carboranyl and metal-carboryne complexes behave very differently from those in classical organometallic complexes. The unique electronic and steric properties of icosahedral carboranyl moiety make the M-C bond in metal-carboranyl complexes inert toward unsaturated molecules, and on the other hand, the sterically demanding carborane cage can induce unexpected C-C coupling reactions. The M-C bonds in metal-carboryne complexes are, however, active toward various kinds of unsaturated molecules and the reactivity patterns are dependent upon the electronic configurations of the metal ions. This account provides an overview of our recent work in this area.boron cluster, carborane, carboryne, insertion, metal-carbon bond

Three‐Component [2+2+2] Cycloaddition of Carboryne, Unactivated Alkene, and Alkyne via Zirconacyclopentane Mediated by Nickel: One‐Pot Synthesis of Dihydrobenzocarboranes

“…[7] For example, nickelacyclopentene incorporating a carboranyl moiety is a reactive intermediate toward alkynes, [5,8] whereas the zirconacyclopentene analogue is inert.…”

“…Our previous work shows that the nature of transition metals dominates the reactivity pattern of the corresponding metallacycles. [7] For example, nickelacyclopentene incorporating a carboranyl moiety is a reactive intermediate toward alkynes, [5,8] whereas the zirconacyclopentene analogue is inert. [9] We have recently found that the zirconacyclopentane incorporating a carboranyl unit is also very thermally stable and inert toward alkenes and alkynes, which is significantly different from those zirconacyclopentanes without carboranyl groups.…”

“…In DME, both selectivity and yield decreased a little (Table 1, entry 5). Phosphine-coordinated nickel complexes all gave the product in yields higher than 91 % but with poor selectivity ( Table 1, entries [6][7][8][9][10][11].…”

Generation and reactivity of o-carborynes

“…It is noted that o-carboryne can also be trapped by transition metals to form a series of metal-carboryne complexes, which has been recently reviewed and will not be covered in this perspective. 7,8 In the following schemes, a black dot and an open cycle stand for a cage carbon and a cage boron atom, respectively; and an unmarked vertex in polyhedron represents a BH vertex.…”

Reaction of [η 5:σ-Me2C(C5H4)(C2B10H10)]Ru(NCCH3)2 with internal alkynes: Synthesis and structural characterization of ruthenium-cyclobutadiene and ruthenacyclopentatriene complexes

“…In view of the significant role of ligands in controlling both chemical and physical properties of the resultant metal complexes [25][26][27][28][29][30][31][32][33], we have introduced a carbon-bridged carboranyl-cyclopentadienyl ligand into ruthenium chemistry [34][35][36][37][38][39][40][41]. The resultant Ru complex [ 5 :-Me 2 C(C 5 H 4 )-(C 2 B 10 H 10 )]Ru(NCCH 3 ) 2 (1) shows a diverse reactivity pattern toward alkynes.…”