Synthesis of a Heterometallic Trinuclear Cluster Containing Ruthenium and Cobalt and Its Reactivity with Internal Alkynes

Abstract

A heterometallic tetrahydrido cluster composed by ruthenium and cobalt, (Cp*Ru) 2 (Cp*Co)(μ-H) 3 (μ 3 -H) (1) (Cp* = η 5 -C 5 Me 5 ), was exclusively synthesized by the reaction of Cp*Ru(μ-H) 4 RuCp* with (Cp*CoCl) 2 in the presence of LiBEt 3 H. X-ray diffraction and VT-NMR studies showed that 1 has a similar structure to the Ir and Rh analogues in terms of the positions of the hydrido ligands, but the size of the trinuclear site is considerably smaller than that of the iridium analogue because of the smaller covalent radius of cobalt. Like the iridium analogue, complex 1 reacted with internal alkynes to yield an equilibrated mixture of perpendicularly coordinated alkyne complexes. However, the structure of the major isomer was different from that of the iridium analogue: the alkyne ligand on the Ru 2 Co core was preferentially coordinated to one of the Ru−Co bonds.

Syntheses and Properties of Triruthenium Polyhydrido Complexes Composed of 1,2,4-tri-tert-butylcyclopentadienyl and p-Cymene Ruthenium Units

“…Each metal center is bound to three hydrides to form a three-legged piano-stool geometry. The positions of hydrides in 3a are similar to those in the isoelectronic Ru 2 Ir and Ru 2 Co complexes [(Cp*Ru) 2 (Cp*Ir)­(μ-H) 3 (μ 3 -H)] and [(Cp*Ru) 2 (Cp*Co) (μ-H) 3 (μ 3 -H)] and their positions were verified by DFT calculations as discussed below.…”

Selective Synthesis of a Triruthenium Pentahydrido Complex with Mixed-Cp Ligands (C5tBu3H2 and C5Me5) and Its Transformation into Face-Capping Benzene Complexes: Fluxionality of a Face-Capping Benzene Ligand Induced by Oxidation

“…However, the introduction of a different metal into the cluster core often results in reactivity different from that of its homometallic analogue. In fact, while we have synthesized various heterobimetallic trinuclear complexes supported by three Cp* groups, no face-capping benzene complexes have been obtained from these heterometallic clusters. Thus, a mixed-ligand triruthenium complex comprised of two types of cyclopentadienyl auxiliaries is desired to reveal the dynamic property of the face-capping benzene ligand.…”

Dehydrogenative Coupling of 4-Substituted Pyridines Catalyzed by a Trinuclear Complex of Ruthenium and Cobalt

“…Complex 1 was completely consumed at the end of the catalytic reaction. At that time, mononuclear species Cp*Co-(dmbpy) (10) and Cp* 2 Ru (11) were observed in the reaction mixture (eq 2). These complexes were characterized by comparing their 1 H NMR spectra with those of the authentic samples synthesized.…”

“…In order to push the limits of the coupling reaction by the ruthenium clusters, the catalytic activity of a heterometallic cluster composed of Ru and Co, (Cp*Ru) 2 (Cp*Co)(μ-H) 3 (μ 3 -H) (1), was investigated. 10 In the first-row transition metals, the metal−ligand interactions are weaker, and the ligand-field splitting is more contracted than those of the second-and thirdrow transition metals. 11 These distinctive features of the first-row transition metals would endow 1 with different reactivity from that of the polyhydrido clusters composed of second-and thirdrow transition metals.…”

“…In order to push the limits of the coupling reaction by the ruthenium clusters, the catalytic activity of a heterometallic cluster composed of Ru and Co, (Cp*Ru) 2 (Cp*Co)­(μ-H) 3 (μ 3 -H) ( 1 ), was investigated . In the first-row transition metals, the metal–ligand interactions are weaker, and the ligand-field splitting is more contracted than those of the second- and third-row transition metals .…”