| Abstract
| - Salts of the ruthenocenylmethylium cation, 1+, can be synthesized from the reaction ofruthenocenylmethanol with either Brønsted or Lewis acids. The X-ray crystal structures ofthe tetrakis{3,5-bis(trifluoromethyl)phenyl}borate and trifluoromethanesulfonate salts of1+ reveal that the methylium carbon is bound to the ruthenium with Ru−C bond lengths inthe range 2.251(9)−2.40(1) Å and confirm the description of the cation structure asη5-cyclopentadienyl-η6-fulvene-ruthenium(II). The UV−vis spectrum of 1+ shows a d−dtransition at an energy similar to those of ruthenocene and the η5-cyclopentadienyl-η6-benzeneruthenium(II) cation, but with increased absorptivity. Cyclic voltammetry indicatesthat 1+ is reduced at considerably less negative potential than its isomer, the η5-cyclopentadienyl-η6-benzene-ruthenium(II) cation. Chemical reduction with sodium amalgamin tetrahydrofuran leads to the formation of methylruthenocene, 1,2-bis(ruthenocenyl)ethane,and bis(ruthenocenylmethyl)ether. Reaction of 1+ with triphenylphosphine affords the(ruthenocenylmethyl)triphenylphosphonium cation; the crystal structure of the dichloromethane solvate of its tetrafluoroborate salt has been determined. Density functionalcalculations closely reproduce the crystallographically determined geometry of 1+ and allowrationalization of some characteristics of its structure, spectroscopy, and reactivity. Thecalculations suggest that the ferrocenylmethylium cation, 3+, has a geometry similar to 1+with similar orbital structure, albeit with considerably more d-character to the occupiedfrontier orbitals.
- Salts of the ruthenocenylmethylium cation have been isolated by reaction of ruthenocenylmethanol with acids; X-ray crystal structures are consistent with the description of the cation as η5-cyclopentadienyl-η6-fulveneruthenium(II). The electronic structure of the cation has been investigated by spectroscopic, electrochemical, and density functional methods.
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