Exploiting the Electronic Tuneability of Carboranes as Supports for Frustrated Lewis Pairs.

ABSTRACT: The first example of a carborane with a catecholborolyl substituent, [1-Bcat-2-Ph-closo-1,2-C?B₁₀H₁₀] (1), has been prepared and characterized and shown to act as the Lewis acid component of an intermolecular frustrated Lewis pair in catalyzing a Michael addition. In combination with B(C?F?)? the C-carboranylphosphine [1-PPh?-closo-1,2-C?B₁₀H₁₁] (IVa) is found to be comparable with PPh?(C?F?) in its ability to catalyze hydrosilylation, whilst the more strongly basic B-carboranylphosphine [9-PPh?-closo-1,7-C?B₁₀H₁₁] (V) is less effective and the very weakly basic species [?-2,2'-PPh-{1-(1'-1',2'-closo-C?B₁₀H₁₀)-1,2-closo-C?B₁₀H₁₀}] (IX) is completely ineffective. Base strengths are rank-ordered via measurement of the ¹J ³¹P-⁷⁷Se coupling constants of the phosphineselenides [1-SePPh?-closo-1,2-C?B₁₀H₁₁] (2), [9-SePPh?-closo-1,7-C?B₁₀H₁₁] (3), and [SePPh?(C?F?)] (4).

SUBMITTER: Benton A 

PROVIDER: S-EPMC6321043 | biostudies-literature | 2018 Nov

REPOSITORIES: biostudies-literature