Volume 20, Issue 49 p. 16216-16227
Full Paper

Influence of Cyclopentadienyl Ring-Tilt on Electron-Transfer Reactions: Redox-Induced Reactivity of Strained [2] and [3]Ruthenocenophanes

Dr. Andrew D. Russell

Dr. Andrew D. Russell

School of Chemistry, University of Bristol, Bristol, BS8 1TS (UK)

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Prof. Joe B. Gilroy

Prof. Joe B. Gilroy

School of Chemistry, University of Bristol, Bristol, BS8 1TS (UK)

Present Address: Department of Chemistry, The University of Western Ontario, 1151 Richmond Street, London, ON (Canada) N6A 5B7

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Prof. Kevin Lam

Prof. Kevin Lam

Department of Chemistry, University of Vermont, Burlington VT 05405-0125 (USA)

Present Address: Nazarbayev University, School of Science and Technology, 53 Kabanbay Batyr Ave, Block 7, Office 7107, 0100000, Astana (Republic of Kazakhstan)

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Dr. Mairi F. Haddow

Dr. Mairi F. Haddow

School of Chemistry, University of Bristol, Bristol, BS8 1TS (UK)

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Prof. Jeremy N. Harvey

Corresponding Author

Prof. Jeremy N. Harvey

School of Chemistry, University of Bristol, Bristol, BS8 1TS (UK)

Jeremy N. Harvey, School of Chemistry, University of Bristol, Bristol, BS8 1TS (UK)

William E. Geiger, Department of Chemistry, University of Vermont, Burlington VT 05405-0125 (USA)

Ian Manners, School of Chemistry, University of Bristol, Bristol, BS8 1TS (UK)

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Prof. William E. Geiger

Corresponding Author

Prof. William E. Geiger

Department of Chemistry, University of Vermont, Burlington VT 05405-0125 (USA)

Jeremy N. Harvey, School of Chemistry, University of Bristol, Bristol, BS8 1TS (UK)

William E. Geiger, Department of Chemistry, University of Vermont, Burlington VT 05405-0125 (USA)

Ian Manners, School of Chemistry, University of Bristol, Bristol, BS8 1TS (UK)

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Prof. Ian Manners

Corresponding Author

Prof. Ian Manners

School of Chemistry, University of Bristol, Bristol, BS8 1TS (UK)

Jeremy N. Harvey, School of Chemistry, University of Bristol, Bristol, BS8 1TS (UK)

William E. Geiger, Department of Chemistry, University of Vermont, Burlington VT 05405-0125 (USA)

Ian Manners, School of Chemistry, University of Bristol, Bristol, BS8 1TS (UK)

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First published: 08 October 2014
Citations: 5

Graphical Abstract

Strained ruthenocenophanes undergo dimerization following electron loss to form stable and isolable dicationic dimer complexes. These species undergo homolytic cleavage of the RuRu bond upon addition of radical sources, facilitating new reactivity modes including reactivity at the metal centre and an unusual η5–η3 haptrotropic Cp ring slip.

Abstract

In contrast to ruthenocene [Ru(η5-C5H5)2] and dimethylruthenocene [Ru(η5-C5H4Me)2] (7), chemical oxidation of highly strained, ring-tilted [2]ruthenocenophane [Ru(η5-C5H4)2(CH2)2] (5) and slightly strained [3]ruthenocenophane [Ru(η5-C5H4)2(CH2)3] (6) with cationic oxidants containing the non-coordinating [B(C6F5)4] anion was found to afford stable and isolable metalmetal bonded dicationic dimer salts [Ru(η5-C5H4)2(CH2)2]2[B(C6F5)4]2 (8) and [Ru(η5-C5H4)2(CH2)3]2[B(C6F5)4]2 (17), respectively. Cyclic voltammetry and DFT studies indicated that the oxidation potential, propensity for dimerization, and strength of the resulting RuRu bond is strongly dependent on the degree of tilt present in 5 and 6 and thereby degree of exposure of the Ru center. Cleavage of the RuRu bond in 8 was achieved through reaction with the radical source [(CH3)2NC(S)SSC(S)N(CH3)2] (thiram), affording unusual dimer [(CH3)2NCS2Ru(η5-C5H4)(η3-C5H4)C2H4]2[B(C6F5)4]2 (9) through a haptotropic η5–η3 ring-slippage followed by an apparent [2+2] cyclodimerization of the cyclopentadienyl ligand. Analogs of possible intermediates in the reaction pathway [C6H5ERu(η5-C5H4)2C2H4][B(C6F5)4] [E=S (15) or Se (16)] were synthesized through reaction of 8 with C6H5EEC6H5 (E=S or Se).