om300432j_si_001.cif (18.99 kB)
New Acyclic (π-Allyl)-closo-rhodacarboranes with an Agostic CH3···Rh Bonding Interaction That Operate as Unmodified Rhodium-Based Catalysts for Alkene Hydroformylation
dataset
posted on 2016-02-20, 12:17 authored by Konstantin
I. Galkin, Sergey E. Lubimov, Ivan A. Godovikov, Fedor M. Dolgushin, Alexander F. Smol’yakov, Elena A. Sergeeva, Vadim A. Davankov, Igor T. ChizhevskyA series of new agostic (CH3···Rh)
(π-allyl)-closo-rhodacarboranes (π-allyl
= 1,1-dimethylallyl,
1,2-dimethylallyl, 1,1,2-trimethylallyl, 1,2,3-trimethylallyl), stable
in the solid state, have been synthesized via one-pot reactions between
the K+ salts of the [7-R-8-R′-7,8-nido-C2B9H10]− monoanions
(1a, R = R′ = Me; 1b, R,R′
= μ-(o-xylylene); 1c, R,R′ = μ-(CH2)3) and the di-μ-chloro
cyclooctene rhodium dimer [(η2-C8H14)4Rh2(μ-Cl)2] (2) in the presence of a 3-fold excess of the conjugated 1,3-dienes
2-methylbuta-1,3-diene (isoprene, 3), 2,3-dimethylbuta-1,3-diene
(4), and 3-methylpenta-1,3-diene (5). The
agostic structures of [3-{(1–3-η3)-1,1-dimethylallyl}-1,2-(CH3)2-3,1,2-closo-RhC2B9H9] (7a) and [3-{(1–3-η3)-1,1,2-trimethylallyl}-1,2-(CH3)2-3,1,2-closo-RhC2B9H9] (8a) have been unambiguously confirmed by single-crystal X-ray
diffraction studies. Two of these π-allyl complexes prepared
were evaluated for their efficacy in hydroformylation of the model
alkenes under syngas (CO/H2) using supercritical carbon
dioxide (scCO2) as the solvent, and both display excellent
conversion and high regioselectivity in the formation of aldehyde
products.