The Chemistry of Triruthenium Hydrocarbyls (Metal Clusters)

Holmgren, Jennifer Salem

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Description

Title

The Chemistry of Triruthenium Hydrocarbyls (Metal Clusters)

Author(s)

Holmgren, Jennifer Salem

Issue Date

1986

Department of Study

Chemistry

Discipline

Chemistry

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

Ph.D.

Degree Level

Dissertation

Keyword(s)

Chemistry, Inorganic

Abstract

• The triruthenium methylidyne cluster, HRu(,3)(CO)(,10)((mu)(,3)-CH), was prepared by a hydride addition/protonation sequence from HRu(,3)(CO)(,10)((mu)-COCH(,3)). Variable temperature ('1)H and ('13)C NMR experiments suggest the intermediacy of a formyl complex, presumably HRu(,3)(CO)(,9)(C(H)O)((mu)-COCH(,3))('-) , in the preparation of HRu(,3)(CO)(,10)((mu)(,3)-CH). The methylidyne cluster, HRu(,3)(CO)(,10)((mu)(,3)-CH), rearranges rapidly (-10(DEGREES)C) to the isomeric carbonylmethylidyne cluster, H(,2)Ru(,3)(CO)(,9)((mu)(,3)-CCO), via intramolecular coupling of the carbyne ligand and a cluster-bound carbonyl. Hydrogenation of H(,2)Ru(,3)(CO)(,9)((mu)(,3)-CCO) yields H(,3)Ru(,3)(CO)(,9)((mu)(,3)-CH), demonstrating that this C-C coupling process is reversible.
• The carbonylmethylidyne cluster, H(,2)Ru(,3)(CO)(,9)((mu)(,3)-CCO), is reduced to the vinylidene cluster, H(,2)Ru(,3)(CO)(,9)((mu)-CCH(,2)), with BH(,3)(.)THF. The carbonylmethylidyne cluster, H(,2)Ru(,3)(CO)(,9)((mu)(,3)-CCO), reacts with nucleophiles at the apical carbon atom. Reaction with MeOH or H(,2)O provides H(,3)Ru(,3)(CO)(,9)((mu)(,3)-CC(O)OMe) and H(,3)Ru(,3)(CO)(,9)((mu)(,3)-CC(O)OH), respectively. A hydride addition/protonation sequence from the carbonylmethylidyne, H(,2)Ru(,3)(CO)(,9)((mu)(,3)-CCO), gives the formylmethylidyne complex, H(,3)Ru(,3)(CO)(,9)((mu)(,3)-CC(O)H). The latter reacts with H(,2) to give the ethylidyne cluster, H(,3)Ru(,3)(CO)(,9)((mu)(,3)-CCH(,3)).
• The triruthenium methylene cluster, Ru(,3)(CO)(,10)((mu)-CO)((mu)-CH(,2)), is prepared by the reaction of diazomethane and Ru(,3)(CO)(,12). Reactivity studies point to facile C-C bond formation involving the cluster bound methylene and added diazomethane or added CO. Reaction with added methylene provides the H(,2)Ru(,3)(CO)(,9)((mu)-CCH(,2)) while reaction with CO provides Ru(,3)(CO)(,12) and ketene. The methylene cluster, Ru(,3)(CO)(,10)((mu)-CO)((mu)-CH(,2)), thermally rearranges to the carbonylmethylidyne cluster, H(,2)Ru(,3)(CO)(,9)((mu)(,3)-CCO). This rearrangement probably involves the previously discussed methylidyne cluster, HRu(,3)(CO)(,10)((mu)(,3)-CH). The trimethylsilyl substituted alkylidene cluster, Ru(,3)(CO)(,10)((mu)-CO)((mu)-CH(,2)), has also been prepared and its reactivity investigated.
• Spin saturation transfer experiments on Ru(,3)(CO)(,10)((mu)-CO)((mu)-CH(,2)) suggest that the methylene unit can move over the cluster face, presumably via a bridge-to-terminal isomerization process.
• Reaction of diazomethane with the phosphine substituted triruthenium cluster, Ru(,3)(CO)(,10)(dppm), yields the novel cluster, Ru(,3)(CO)(,7)((eta)('3)-(C,C,O),(mu)(,3)-COCH(,2))((mu)-CH(,2))(dppm). This cluster was characterized spectroscopically as well as by a single crystal X-ray diffraction study. The cluster contains a ketene ligand and a bridging methylene ligand. Surprisingly, each of the three atoms in the C-C-O unit, the ketene ligand, is bound to a different metal atom in the cluster. On addition of CO, the ketene and methylene ligands in Ru(,3)(CO)(,7)((eta)('3)-(C,C,O),(mu)(,3)-COCH(,2))((mu)-CH(,2))(dppm) couple to form an oxaallyl unit, while the triruthenium cluster degrades to a ruthenium dimer, Ru(,2)(CO)(,5)((eta)('4)-(C,C,C,O),(mu)-CH(,2)C(O)CH(,2))(dppm), which was characterized by single crystal X-ray diffraction.

Graduation Semester

1986

Type of Resource

text

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