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Reactivity of Diphenylbutadiyne with a Hexaruthenium Dihydride. Unusual 1,1- and trans-1,2-Additions of Two Hydrogen Atoms to an Internal CC Triple Bond§

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posted on 13.03.2006, 00:00 by Javier A. Cabeza, Ignacio del Río, José M. Fernández-Colinas, Pablo García-Álvarez, Daniel Miguel
The reactions of the basal edge-bridged square pyramidal hexanuclear cluster [Ru63-H)252-ampy)(μ-CO)2(CO)14] (1; H2ampy = 2-amino-6-methylpyridine) with diphenylbutadiyne give mixtures of cluster compounds, the composition of which depends on the reaction time and temperature. The following products have been isolated and characterized:  [Ru652-ampy)(μ53-PhCCCCH2Ph)(μ-CO)(CO)14] (two isomers, 2 and 3), [Ru652-ampy)(μ54-trans-PhCCCHCHPh)(μ-CO)(CO)14] (4), and [Ru552-ampy)(μ42-trans-PhCCCHCHPh)(η6-PhMe)(μ-CO)(CO)9] (5). In all products, the ampy ligand is attached to five metal atoms through its nitrogen atoms, in the same way as in complex 1. These compounds represent unusual examples of 1,1- and trans-1,2-additions of two hydrogen atoms to an internal CC triple bond, since 2 and 3 contain a hydrocarbon ligand that arises from the migration of the original hydrides of 1 onto a terminal carbon atom of the diyne C4 chain, and 4 and 5 contain a 1,4-diphenyl-trans-butenyne ligand. The reaction pathway 1 + PhC2C2Ph → 2345 has been established by studying the individual thermolysis of compounds 24 and reactions of 1 with diphenylbutadiyne at different reaction times and temperatures.