Reactions of co-ordinated ligands. Part 34. Synthesis, structure, and reactivity of cationic dieneruthenium complexes; crystal structures of [Ru(η4-C6H8)(CO)(η-C5H 5)][BF4] and [Ru(η3-C6H9)(CO)(η-C5H 5)]

Mark Crocker, Michael Green, Carolyn E. Morton, Katharine R. Nagle, A. Guy Orpen

Research output: Contribution to journalArticlepeer-review

36 Scopus citations

Abstract

Ultraviolet irradiation of a solution of [Ru(NCMe)(CO)2(η-C5H5)][BF4] in MeCN affords [Ru(NCMe)2(CO)(η-C5H5)][BF4] (1) in high yield. The acetonitrile ligands in complex (1) are substitution labile and reaction with buta-1,3-diene, isoprene, 1,4-diphenylbuta-1,3-diene, and cyclohexa-1,3-diene gives the complexes [Ru(η4-1,3-diene)(CO)(η-C5H5)][BF 4]. An X-ray crystallographic study on the cyclohexa-1,3-diene cation established that the molecule adopts an exo configuration, the C6 ring showing substantial folding. Whereas trans-penta-1,3-diene reacts with complex (1) to form an analogous complex, cis-penta-1,3-diene affords an isomeric mixture of exo and endo isomers of both the cis- and trans-penta-1,3-diene complexes. This is discussed in terms of a hydrogen-shift process involving a RuII → RuIV redox reaction. Cyclo-octa-1,3-diene does not react with complex (1), however, both cyclo-octa-1,5-diene and cyclo-octatetraene react to form [Ru(η4-1,5-C8H12)(CO)(η-C 5H5)][BF4] and [Ru(η4-C8H8)(CO)(η-C5H 5)][BF4], u.v. irradiation of the latter complex affording [Ru(η6-C8H8)(η-C5H 5)][BF4]. This is possibly related to a close relationship between the fragments Ru(CO)(η-C5H5)+ and Cr(CO)4. Reaction of the buta-1,3-diene and isoprene cations with Li[CuPh2] and Na[BH3(CN)] respectively affords η3-allyl complexes. An X-ray crystallographic study on the η3-cyclohexenyl complex, [Ru(η3-C6H9)(CO)(η-C5H 5)], obtained on reaction of the cyclohexa-1,3-diene cation with Na[BH3(CN)] showed that the C6 ring adopts a boat conformation. Consideration of this observation along with 1H n.m.r. data is used to show that nucleophilic reagents attack the opposite face of the C6 ring to which the ruthenium is bonded. The cyclo-octa-1,5-diene complex reacts with Na[BH3(CN)] to form a 1,4,5-η3-C8H13 complex, which does not isomerise to a 1,2,3-η3-bonded species.

Original languageEnglish
Pages (from-to)2145-2153
Number of pages9
JournalJournal of the Chemical Society, Dalton Transactions
Issue number10
DOIs
StatePublished - 1985

ASJC Scopus subject areas

  • General Chemistry

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