Bis(phosphine)hydridorhodacarborane Derivatives of 1,1′-Bis(ortho-carborane) and Their Catalysis of Alkene Isomerization and the Hydrosilylation of Acetophenone

• Published in: Inorganic chemistry Vol. 59; no. 3; pp. 2011 - 2023
• Main Authors: Chan, Antony P.Y, Parkinson, John A, Rosair, Georgina M, Welch, Alan J
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 03-02-2020
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/acs.inorgchem.9b03351

Deprotonation of [7-(1′-closo-1′,2′-C2B10H11)-nido-7,8-C2B9H11]− and reaction with [Rh­(PPh3)3Cl] results in isomerization of the metalated cage and the formation of [8-(1′-closo-1′,2′-C2B10H11)-2-H-2,2-(PPh3)2-closo-2,1,8-RhC2B9H10] (1). Similarly, deprotonation/metalation of [8′-(7-nido-7,8-C2B9H11)-2′-(p-cymene)-closo-2′,1′,8′-RuC2B9H10]− and [8′-(7-nido-7,8-C2B9H11)-2′-Cp*-closo-2′,1′,8′-CoC2B9H10]− affords [8-{8′-2′-(p-cymene)-closo-2′,1′,8′-RuC2B9H10}-2-H-2,2-(PPh3)2-closo-2,1,8-RhC2B9H10] (2) and [8-(8′-2′-Cp*-closo-2′,1′,8′-CoC2B9H10)-2-H-2,2-(PPh3)2-closo-2,1,8-RhC2B9H10] (3), respectively, as diastereoisomeric mixtures. The performances of compounds 1–3 as catalysts in the isomerization of 1-hexene and in the hydrosilylation of acetophenone are compared with those of the known single-cage species [3-H-3,3-(PPh3)2-closo-3,1,2-RhC2B9H11] (I) and [2-H-2,2-(PPh3)2-closo-2,1,12-RhC2B9H11] (V), the last two compounds also being the subjects of 103Rh NMR spectroscopic studies, the first such investigations of rhodacarboranes. In alkene isomerization all the 2,1,8- or 2,1,12-RhC2B9 species (1–3, V) outperform the 3,1,2-RhC2B9 compound I, while for hydrosilylation the single-cage compounds I and V are better catalysts than the double-cage species 1–3.