Agostic bonding in pincer complexes of ruthenium

Citation
Dg. Gusev et al., Agostic bonding in pincer complexes of ruthenium, ORGANOMETAL, 19(9), 2000, pp. 1734-1739
Citations number
46
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Organic Chemistry/Polymer Science
Journal title
ORGANOMETALLICS
ISSN journal
0276-7333 → ACNP
Volume
19
Issue
9
Year of publication
2000
Pages
1734 - 1739
Database
ISI
SICI code
0276-7333(20000501)19:9<1734:ABIPCO>2.0.ZU;2-T
Abstract
High-yield preparations have been developed for 16-e square-pyramidal compl exes of ruthenium(II) RuCl(CO)[2,6-(CH2PBu2t)(2)C6H3] (1), RuHCl[1,3-(CH2PB u2t)(2)C6H4] (2), and RuHI[1,3-(CH2PBu2t)(2)C6H4] (3). NMR and X-ray studie s have revealed strong eta(2) CH bonding in the Ru[1,3-(CH2PBu2t)(2)C6H4] f ragment of 2 and 3. These complexes show stretched agostic C-H bonds, elong ated ipso-C-Ru distances, reduced (1)J(CH) couplings, and large IPR shifts in H-1 NMR. A consistent picture has emerged of a stronger agostic bonding and greater C-H bond activation in the eta(2) C-H trans to chloride in 2. T his finding is attributed to stronger pi-donor properties of chloride compa red to iodide and increased back-donation into the antibonding orbital of t he eta(2) C-H. Analysis of the X-ray and NMR T-1 data has also indicated th e presence of an attractive interaction, dihydrogen bonding, between the ag ostic C-H hydrogen and neighboring hydride in 2 and 3.