title: Interaction of thioether groups at the open coordination sites of palladium(II) and platinum(II) complexes probed by luminescence spectroscopy at variable pressure.
abstract: The crystal structures of [PtCl(2)(ttcn)], [PdCl(2)(ttcn)], [Pt(ethylenediamine)(ttcn)](PF(6))(2), and [Pd(ethylenediamine)(ttcn)](PF(6))(2) (ttcn = 1,4,7-trithiacyclononane) show short apical metal---S(ttcn) distances, qualitatively indicating an interaction. Luminescence spectroscopy was used to study these crystalline complexes at room temperature and variable hydrostatic pressure. The luminescence band maximum of [PdCl(2)(ttcn)] shows a pressure-induced blue shift of +6 cm(-1)/kbar, while the platinum(II) compounds show a red shift of approximately -20 cm(-1)/kbar. This difference is rationalized in terms of a competition between blue shifts due to pressure-induced metal-ligand bond shortening in the equatorial plane and increasing out-of-plane distance of the metal center, and a red shift due to the approach of the apical sulfur donor to the metal center. Density functional theory (DFT) calculations indicate d-d luminescence transitions and a different nature of the highest occupied molecular orbital (HOMO) for [PdCl(2)(ttcn)] than for [PtCl(2)(ttcn)], while the lowest unoccupied molecular orbitals (LUMOs) are identical in character. This electronic structure difference is used to rationalize the different pressure effects.
authors.affiliation: Département de Chimie, Université de Montréal, QC H3C 3J7, Canada.
authors.forename: Esther
authors.initials: E
authors.lastname: Pierce
authors.forename: Etienne
authors.initials: E
authors.lastname: Lanthier
authors.forename: Caroline
authors.initials: C
authors.lastname: Genre
authors.forename: Yurii
authors.initials: Y
authors.lastname: Chumakov
authors.forename: Dominique
authors.initials: D
authors.lastname: Luneau
authors.forename: Christian
authors.initials: C
authors.lastname: Reber
mesh_terms: D001665:Binding Sites; D003198:Computer Simulation; D018360:Crystallography, X-Ray; D008163:Luminescent Measurements; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000737:chemistry*; D010165:Palladium / Q000737:chemistry*; D010984:Platinum / Q000737:chemistry*; D011312:Pressure; D013440:Sulfides / Q000737:chemistry*
chemical_list: D009942:Organometallic Compounds; D013440:Sulfides; D010984:Platinum; D010165:Palladium