Interaction of thioether groups at the open coordination sites of palladium(II) and platinum(II) complexes probed by luminescence spectroscopy at variable pressure.
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.
Pierce
Esther
E
Département de Chimie, Université de Montréal, QC H3C 3J7, Canada.
Lanthier
Etienne
E
Genre
Caroline
C
Chumakov
Yurii
Y
Luneau
Dominique
D
Reber
Christian
C
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*
D009942:Organometallic Compounds; D013440:Sulfides; D010984:Platinum; D010165:Palladium