19529-00-1Relevant articles and documents
Yamamoto et al.
, p. 1089 (1968)
Solid-State structure and solution reactivity of [(Ph3P)4Ru(H)2] and related Ru(II) complexes used in catalysis: A reinvestigation
Samouei, Hamidreza,Miloserdov, Fedor M.,Escudero-Adn, Eduardo C.,Grushin, Vladimir V.
, p. 7279 - 7283 (2015/09/08)
X-ray analysis of [(Ph3P)4Ru(H)2] (1) prepared by a literature procedure [ Young, R.; Wilkinson, G. Inorg. Synth. 1990, 28, 337 ] shows that 1 is cocrystallized with PPh3, explaining the previously reported observations of free phosphine in solutions of 1. Lattice PPh3-free forms of 1 have also been obtained, structurally characterized, and found to generate small quantities of uncoordinated PPh3 and another species (A) in solution. Against previous beliefs, however, A is not [(Ph3P)3Ru(H)2] (2), but [(Ph3P)3Ru(H2)(H)2] (3) that forms in the reaction of 1 with adventitious water. This reaction apparently occurs via PPh3 loss from 1 to give 2, followed by H2O coordination, Ru(H)(OH2)/Ru(H2)(OH) rearrangement, H2 loss, and dimerization to give [(Ph3P)4Ru2(H)2(μ-OH)2] (4). The H2 thus produced is trapped with 2 to give 3. Complexes 3·0.5C6H6, 3·2THF, 4·2H2O, [(Ph3P)3Ru(N2)(H)2] (5), and [(Ph3P)2(H)Ru(μ-H)3Ru(PPh3)3]·0.5THF (6·0.5THF) have been structurally characterized for the first time. Also for the first time, a single-crystal X-ray diffraction study of the long-known [(Ph3P)4RuCl2] (7) has been performed to finally demonstrate that 7 is, in fact, [(Ph3P)3RuCl2]·PPh3, precisely as proposed by Hoffman and Caulton as early as 1975 [ Hoffman, P.R.; Caulton, K.G. J. Am. Chem. Soc. 1975, 97, 4221 ].
Michael reaction of stabilized carbon nucleophiles catalyzed by [RuH2(PPh3)4]
Gómez-Bengoa, Enrique,Cuerva, Juan M.,Mateo, Cristina,Echavarren, Antonio M.
, p. 8553 - 8565 (2007/10/03)
The Michael reaction of active methylene compounds lacking cyano groups such as malonates, β-ketoesters, 1,3-diketones, 1,1-disulfones, nitrocompounds, Meldrum acid, and anthrone with common acceptors proceeds in acetonitrile solution in the presence of [RuH2(PPh3)4] as the catalyst. Cyano acetates, more acidic than malonates in organic solvents, are also excellent substrates for this reaction. In a number of cases, intramolecular aldol reactions catalyzed by [RuH2(PPh3)4] were also observed as side reactions. Catalysis by other ruthenium and rhodium complexes has been examined. Selectivity studies performed with malonate and disulfone donors indicate that the catalyst selectively activates Michael donors that can coordinate with ruthenium(II). Additionally, it has been shown that the reaction requires the presence of free phosphine. Therefore, the Michael reaction of stabilized enolates appears to be a ruthenium- and phosphine-catalyzed reaction. From a practical point of view, the use of readily prepared [RuH2(PPh3)4] as the catalyst in acetonitrile provided the best solution for the Michael reaction of active methylene compounds.
