Bonding and electron delocalization in ruthenium(III) σ-arylacetylide radicals [trnsCl(η2-dppe)2Rue≡C(4-C 6H4X)]+ (X = NO2, C(O)H, C(O)Me, F, H, OMe, NMe2): Misleading aspects of the ESR anisotropy

Nicolas Gauthier, Noureddine Tehouar, Frédéric Justaud, Gilles Argouarch, Marie P. Cifuentes, Loic Toupet, Daniel Touchard, Jean Francois Halet, Stéphane Rigaut, Mark G. Humphrey, Karine Costuas, Frédéric Paul*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

69 Citations (Scopus)

Abstract

The bonding within the series of [trans-Cl(η2-dppe) 2RuC≡C(4-C6H4X)]n+ complexes (1-Xn+; n = 1, 0 and X = NO2, C(O)H, C(O)Me, F, H, OMe, NMe2) has been examined by IR, ESR, and UV-vis-near-IR spectroscopy together with computational modeling. A strong substituent effect is evidenced for radical delocalization from the metal to the functional arylacetylide fragment. This effect is also apparent in the large anisotropy change of their ESR signatures. DFT calculations substantiate these experimental observations and permit discussion of the influence of the X substituent on spin delocalization in compounds containing isolobal metal fragments. Evidence is given that the ESR anisotropy alone cannot reliably be used to compare the metallic character of the unpaired electrons in closely related families of pseudo-octahedral cationic Ru(III) functional arylacetylides with rhombic symmetry when the complexes possess different coordination spheres. ESR anisotropy constitutes nevertheless a useful benchmark for this purpose within the presently investigated 1-X+ family.

Original languageEnglish
Pages (from-to)2253-2266
Number of pages14
JournalOrganometallics
Volume28
Issue number7
DOIs
Publication statusPublished - 13 Apr 2009
Externally publishedYes

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