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

Abstract

The reactions of the basal edge-bridged square pyramidal hexanuclear cluster [Ru6(μ3-H)2(μ5-κ2-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: [Ru6(μ5-κ2-ampy)(μ5-η3-PhCCCCH2Ph)(μ-CO)(CO)14] (two isomers, 2 and 3), [Ru6(μ5-κ2-ampy)(μ5-η4-trans-PhCCCHCHPh)(μ-CO)(CO)14] (4), and [Ru5(μ5-κ2-ampy)(μ4-η2-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 → 2 → 3 → 4 → 5 has been established by studying the individual thermolysis of compounds 2−4 and reactions of 1 with diphenylbutadiyne at different reaction times and temperatures.