Syntheses and Structures of Triple-Decker Complexes Incorporating Octamethylruthenocene and Nonamethylruthenocene

• Published in: Organometallics 2019-06, Vol.38 (12), p.2573-2581
• Main Authors: McBride, Joseph J, Casad, Timothy J, Cheung, Emina E, Pike, Robert D, Watson, Eric J
• Format: Article
• Language: English
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/acs.organomet.9b00250

Five new diruthenium triple-decker complexes were synthesized by the reaction of ruthenium electrophiles with metallocenes of ruthenium. At 40 °C, the reaction of [(C5R5)­Ru­(NCMe)3]+ (R = H, Me) with octamethylruthenocene, Cp′RuCp′ (Cp′ = C5Me4H), afforded orange diruthenium triple-decker complexes [(C5R5)­Ru­(μ-Cp′)­RuCp′]+ by electrophilic addition of [(C5R5)­Ru]+ to a Cp′ ring of octamethylruthenocene. However, at 100 °C, [(C5H5)­Ru]+ abstracted a Cp′ ring from Cp′RuCp′ generating [Cp′Ru]+ and CpRuCp′ (Cp = C5H5) by a ligand transfer reaction. Subsequent addition of the newly generated cation [Cp′Ru]+ to an equivalent of Cp′RuCp′ afforded a triple-decker complex with three tetramethylcyclopentadienyl rings, [Cp′Ru­(μ-Cp′)­RuCp′]+. Analogous reactions between [(C5R5)­Ru­(NCMe)3]+ and nonamethylruthenocene, Cp′RuCp* (Cp* = C5Me5), afforded orange triple-decker complexes [(C5R5)­Ru­(μ-Cp′)­RuCp*]+ by direct electrophilic addition. These reactions with the asymmetric metallocene, Cp′RuCp*, demonstrate a remarkable degree of regioselectivity such that electrophiles add only to the Cp′ ring and never to the Cp* ring of nonamethylruthenocene. The five diruthenium triple-decker complexes have been fully characterized by NMR spectroscopy, elemental analyses, and single crystal X-ray diffraction analyses, and nonamethylruthenocene, Cp*RuCp′, has been characterized by NMR and elemental analysis.