Arene−Ruthenium Complexes of 1,1′-Bis(ortho-carborane): Synthesis, Characterization, and Catalysisстатья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
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Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 27 сентября 2019 г.
Авторы:
Jeans Rebekah J.,
Chan Antony P.Y,
Riley Laura E.,
James Taylor,
Rosair Georgina M.,
Welch Alan J.,
Sivaev Igor B.
Аннотация:Deprotonation of 1,1′-bis(ortho-carborane) with n-BuLi in THF followed by reaction with [RuCl2(p-cymene)]2 affords, in addition to the known compound [Ru(κ3-2,2′,3′-{1-(1′-closo-1′,2′-C2B10H10)-closo-1,2-C2B10H10)}(pcymene)] (I), a small amount of a new species, [Ru(κ3-2,2′,11′-{1-(7′-nido-
7′,8′-C2B9H11)-closo-1,2-C2B10H10)}(p-cymene)] (1a), with two B-agostic B−H⇀Ru bonds, making the bis(carborane) unit a closo-nido-X(C)L2 ligand, a previously unreported bonding mode. Similar species were also formed with arene = benzene (1b), mesitylene (1c), and hexamethylbenzene (1d), although in the last two cases the metallacarborane-carborane species [1-(1′-closo-1′,2′-C2B10H11)-3-(arene)-closo-3,1,2-RuC2B9H10)], 2c and 2d, were also isolated. With the bis(ortho-carborane) transfer reagent [Mg(κ2-2,2′-{1-(1′-closo-1′,2′-C2B10H10)-closo-1,2-C2B10H10)}(DME)2], the target compounds [Ru(κ3-2,2′,3′-{1-(1′-closo-1′,2′-C2B10H10)-closo-1,2-C2B10H10)}(arene)], 4b and 4d, were prepared in reasonable-to-good yields, although for arene = benzene and mesitylene small amounts of the unique paramagnetic species [{Ru(arene)}2(μ-Cl)(μ-κ4-2,2′,3,3′-{1-(1′-closo-1′,2′-C2B10H9)-closo-1,2-C2B10H9})], 3b and 3c, were also formed. In compounds 3, the bis(carborane) acts as a closo-closo-
X4(C,C′,B,B′) ligand to the Ru2 unit. In I, 4b, and 4d, the B-agostic B−H⇀Ru bond is readily cleaved by MeCN, affording compounds [Ru(κ2-2,2′-{1-(1′-closo-1′,2′-C2B10H10)-closo-1,2-C2B10H10})(arene)(NCMe)] (5a, 5b, and 5d) and suggesting that I, 4b, and 4d could act as Lewis acid catalysts, which is subsequently shown to be the case for the Diels−Alder cycloaddition reactions between cyclopentadiene and methacrolein, ethylacrolein and E-crotonaldehyde. All new species were
characterized by multinuclear NMR spectroscopy and 1a, 1c, 1d, 2c, 2d, 3b, 3c, 4b, 4d, 5a, 5b, and 5d were also characterized crystallographically.