Reactivity of Arenes, Cycloheptatriene, and Dicyclopentadiene with a Basal Edge-Bridged Square Pyramidal Hexaruthenium Dihydride

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 arenes at high temperature (>110 °C) give [Ru63-H)252-ampy)(η6-arene)(μ-CO)2(CO)11] (arene = C6H6 2a, C6H5Me 2b, 1,4-C6H4Me2 2c). These complexes result from the substitution of the arene for the three CO ligands of the apical Ru atom of 1. Cycloheptatriene reacts with complex 1 in chlorobenzene at reflux temperature to give a mixture of products from which the hexanuclear cluster complexes [Ru63-H)(μ52-ampy)(η5-C7H9)(μ3-CO)(μ-CO)2(CO)11] (3), [Ru63-H)(μ52-ampy)(μ37-C7H7)(μ-CO)2(CO)11] (4), [Ru652-ampy)(μ27-C7H7)2(μ-CO)(CO)9] (5), and [Ru66-C)(μ37-C7H7)2(μ-CO)2(CO)8] (6) have been isolated and characterized. While compound 3 has a terminal η5-cycloheptadienyl ligand, 4 contains a face-capping η52-cycloheptatrienyl ligand, and 5 has two edge-bridging η43-cycloheptatrienyl ligands. Compound 6, a minor product of this reaction, contains an octahedral metallic skeleton with a μ6-carbide and two face-capping η322-cycloheptatrienyl ligands. It has been established that the thermolysis of complex 3 gives 4 and that complex 5 arises from the reaction of 4 with cycloheptatriene. Treatment of dicyclopentadiene with complex 1 in chlorobenzene at reflux temperature has allowed the isolation of [Ru25-C5H5)2(μ-CO)2(CO)2] and three cluster derivatives, [Ru63-H)(μ52-ampy)(η5-C5H5)(μ3-CO)(μ-CO)2(CO)11] (7), [Ru63-H)252-ampy)(η5-C5H5)23-CO)(μ-CO)(CO)9] (8), and [Ru552-ampy)(μ44-C10H10)(μ-CO)2(CO)10] (9). Compounds 7 and 8 are hexanuclear and contain one and two terminal cyclopentadienyl ligands, respectively. The pentanuclear derivative 9 features an unprecedented η22-enyne ligand that derives from the activation of two adjacent H−C(sp2) bonds of dicyclopentadiene. With the exception of compounds 6 and 9, the remaining clusters have the same Ru652-ampy) framework as compound 1 and have the apical Ru atom attached to hydrocarbon ligands.