title: Ambidentate coordination in hydrogen bonded dimethyl sulfoxide, (CH3)2SO...H3O+, and in dichlorobis(dimethyl sulfoxide) palladium(II) and platinum(II) solid solvates, by vibrational and sulfur K-edge X-ray absorption spectroscopy.
abstract: The strongly hydrogen bonded species (CH3)2SO...H3O+ formed in concentrated hydrochloric acid displays a new low energy feature in its sulfur K-edge X-ray absorption near edge structure (XANES) spectrum. Density Functional Theory-Transition Potential (DFT-TP) calculations reveal that the strong hydrogen bonding decreases the energy of the transition S(1s) --> LUMO, which has antibonding sigma*(S-O) character, with about 0.8 eV. Normal coordinate force field analyses of the vibrational spectra show that the SO stretching force constant decreases from 4.72 N cm(-1) in neat liquid dimethyl sulfoxide to 3.73 N cm(-1) for the hydrogen bonded (CH3)2SO...H3O+ species. The effects of sulfur coordination on the ambidentate dimethyl sulfoxide molecule were investigated for the trans-Pd((CH3)2SO)2Cl2, trans-Pd((CD3)2SO)2Cl2 and cis-Pt((CH3)2SO)2Cl2 complexes with square planar coordination of the chlorine and sulfur atoms. The XANES spectra again showed shifts toward low energy for the transition S(1 s) --> LUMO, now with antibonding sigma*(M-Cl, M-S) character, with a larger shift for M = Pt than Pd. DFT-TP calculations indicated that the differences between the XANES spectra of the geometrical cis and trans isomers of the M((CH3)2SO)2Cl2 complexes are expected to be too small to allow experimental distinction. The vibrational spectra of the palladium(II) and platinum(II) complexes were recorded and complete assignments of the fundamentals were achieved. Even though the M-S bond distances are quite similar the high covalency especially of the Pt-S bonds induces significant increases in the S-O stretching force constants, 6.79 and 7.18 N cm(-1), respectively.
authors.affiliation: Department of Physical, Inorganic and Structural Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden.
authors.forename: Emiliana Damian
authors.initials: ED
authors.lastname: Risberg
authors.forename: János
authors.initials: J
authors.lastname: Mink
authors.forename: Alireza
authors.initials: A
authors.lastname: Abbasi
authors.forename: Mikhail Yu
authors.initials: MY
authors.lastname: Skripkin
authors.forename: Laszló
authors.initials: L
authors.lastname: Hajba
authors.forename: Patric
authors.initials: P
authors.lastname: Lindqvist-Reis
authors.forename: Eva
authors.initials: E
authors.lastname: Bencze
authors.forename: Magnus
authors.initials: M
authors.lastname: Sandström
mesh_terms: D004121:Dimethyl Sulfoxide / Q000737:chemistry*; D006860:Hydrogen Bonding; D017550:Spectroscopy, Fourier Transform Infrared; D013057:Spectrum Analysis / Q000379:methods*; D013455:Sulfur / Q000737:chemistry; D013463:Sulfuric Acid Esters / Q000737:chemistry*; D014965:X-Rays
chemical_list: D013463:Sulfuric Acid Esters; D013455:Sulfur; C033522:methyl sulfate; D004121:Dimethyl Sulfoxide