Rhodocenium Complexes Bearing the 1,2,3-Tri-tert-butylcyclopentadienyl Ligand:  Redox-Promoted Synthesis and Mechanistic, Structural and Computational Investigations

• Published in: Organometallics Vol. 17; no. 9; pp. 1716 - 1724
• Main Authors: Donovan-Merkert, Bernadette T, Clontz, C. Reid, Rhinehart, Leslie M, Tjiong, Howard I, Carlin, Clifford M, Cundari, Thomas R, Rheingold, Arnold L, Guzei, Ilia
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 27.04.1998; Amer Chemical Soc
• Subjects: Chemistry; Chemistry, Inorganic & Nuclear; Chemistry, Organic; Physical Sciences; Science & Technology; CYCLOPENTADIENYL LIGANDS; RHODIUM; HEXAFLUOROPHOSPHATE; MOLECULAR-STRUCTURE; CRYSTAL-STRUCTURE; ORGANOMETALLIC CHEMISTRY; 1,2-DI-TERT-BUTYLCYCLOPENTADIENYL LIGAND; IRON; COBALT; 1,3-DI-T-BUTYLCYCLOPENTADIENYL
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/om9707735

Single-electron oxidation of rhodium complexes containing the 1,2,3,5-η-penta-2,4-dienediyl ligand was conducted by electrochemical and chemical means. In all cases, rhodocenium complexes bearing the η5-1,2,3-tri-tert-butylcyclopentadienyl ligand were produced in good yield. The results of single-crystal X-ray diffraction studies revealed the solid-state structures of [Rh(η5-C5H5)(η5-C5 tBu3H2)][PF6] (10a + ) and [Rh(η5-C5H5)(η5-C5 tBu3H2)][BF4] (10b + ). The steric strain in these molecules is apparently relieved by in-plane distortions of the bond lengths and angles of the tri-tert-butylcyclopentadienyl ligand. The results of a deuterium-labeling study revealed the stereochemistry of the ring-closure reaction. Computational studies using the PM3 semiempirical Hamiltonian suggest that oxidation of the pentadienediyl complexes involves removal of an electron from a molecular orbital centered on the pentadienediyl ligand.