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 [Ru6(μ3-H)2(μ5-κ2-ampy)(μ-CO)2(CO)14] (1; H2ampy = 2-amino-6-methylpyridine) with arenes at high temperature (>110 °C)
give [Ru6(μ3-H)2(μ5-κ2-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 [Ru6(μ3-H)(μ5-κ2-ampy)(η5-C7H9)(μ3-CO)(μ-CO)2(CO)11] (3), [Ru6(μ3-H)(μ5-κ2-ampy)(μ3-η7-C7H7)(μ-CO)2(CO)11] (4), [Ru6(μ5-κ2-ampy)(μ2-η7-C7H7)2(μ-CO)(CO)9] (5), and [Ru6(μ6-C)(μ3-η7-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 η5:η2-cycloheptatrienyl ligand, and 5 has two edge-bridging η4:η3-cycloheptatrienyl ligands. Compound 6, a
minor product of this reaction, contains an octahedral metallic skeleton with a μ6-carbide and two face-capping η3:η2:η2-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
[Ru2(η5-C5H5)2(μ-CO)2(CO)2] and three cluster derivatives, [Ru6(μ3-H)(μ5-κ2-ampy)(η5-C5H5)(μ3-CO)(μ-CO)2(CO)11] (7), [Ru6(μ3-H)2(μ5-κ2-ampy)(η5-C5H5)2(μ3-CO)(μ-CO)(CO)9] (8), and [Ru5(μ5-κ2-ampy)(μ4-η4-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 η2:η2-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 Ru6(μ5-κ2-ampy)
framework as compound 1 and have the apical Ru atom attached to hydrocarbon ligands.