title: Solvent-Dependent Structure of Iridium Dihydride Complexes: Different Geometries at Low and High Dielectricity of the Medium.
abstract: The hydride iridium pincer complex [(PCyP)IrH2] (PCyP=cis-1,3-bis[(di-tert-butylphosphino)methyl]cyclohexane, 1) reveals remarkably solvent-dependent hydride chemical shifts, isotope chemical shifts, JHD and T1(min), with rHH increasing upon moving to more polar medium. The only known example of such behaviour (complex [(POCOP)IrH2], POCOP=2,6-(tBu2PO)2C6H3) was explained by the coordination of a polar solvent molecule to the iridium (J. Am. Chem. Soc. 2006, 128, 17114). Based on the existence of an agostic bond between α-C-H and iridium in 1 in all solvents, we argue that the coordination of solvent can be rejected. DFT calculations revealed that the structures of 1 and [(POCOP)IrH2] depend on the dielectric permittivity of the medium and these compounds adopt trigonal-bipyramidal geometries in non-polar media and square-pyramidal geometries in polar media.
authors.affiliation: Centre for Analysis and Synthesis, Department of Chemistry, Lund University, PO Box 124, 22100, Lund, Sweden.
authors.forename: Alexey V
authors.initials: AV
authors.lastname: Polukeev
authors.affiliation: Division of Theoretical Chemistry and Biology, School of Biotechnology, KTH Royal Institute of Technology, 106 91, Stockholm, Sweden.
authors.forename: Rocío
authors.initials: R
authors.lastname: Marcos
authors.affiliation: Division of Theoretical Chemistry and Biology, School of Biotechnology, KTH Royal Institute of Technology, 106 91, Stockholm, Sweden.
authors.forename: Mårten S G
authors.initials: MS
authors.lastname: Ahlquist
authors.affiliation: Centre for Analysis and Synthesis, Department of Chemistry, Lund University, PO Box 124, 22100, Lund, Sweden. ola.wendt@chem.lu.se.
authors.forename: Ola F
authors.initials: OF
authors.lastname: Wendt
keywords: density functional calculations; hydrides; iridium; pincer complexes; solvent effects