title: trans-W(Cmesityl)(dmpe)2H: revealing a highly polar W-H bond and H-mobility in liquid and solid state.
abstract: The isotopomeric complexes trans-W(Cmesityl)[(C(H,D)3)2PCH2CH2P(C(H,D)3)2]2(H,D) 1-4 were prepared. 2 (W(Cmesityl)(dmpe)2D) was used to study the Deuterium Quadrupole Coupling Constant (DQCC) and the ionicity of the W-D bond (DQCC=34.1 kHz; ionicity 85%). 1 (W(Cmesityl)(dmpe)2H) shows several dynamic exchange processes in solution, such as HW/HW, HW/ortho-Memesityl, and HW/H2 exchanges observed by NMR in combination with deuterium labeling studies and double label crossover experiments. Except for the HW/H2, these reactions comprise elementary steps, which also appear along the isomerization pathway of 1 into (2,3,5-trimethylphenylcarbyne)(dmpe)2WH (5) at 60 degrees C. 5 was characterized by an X-ray diffraction study. In the solid state only an HW/Mep exchange process prevails appearing at higher temperatures, which was identified by NMR and by Quasielastic Neutron Scattering. The latter also provided an activation barrier of 5 kcal/mol and a "jump width" for the moving H nucleus in agreement with the HW...Mep distance of the X-ray diffraction study of 1.
authors.affiliation: Anorganisch-chemisches Institut, Universität Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.
authors.forename: Fenglou
authors.initials: F
authors.lastname: Zou
authors.forename: Franck
authors.initials: F
authors.lastname: Furno
authors.forename: Thomas
authors.initials: T
authors.lastname: Fox
authors.forename: Helmut W
authors.initials: HW
authors.lastname: Schmalle
authors.forename: Heinz
authors.initials: H
authors.lastname: Berke
authors.forename: Jürgen
authors.initials: J
authors.lastname: Eckert
authors.forename: Zema
authors.initials: Z
authors.lastname: Chowdhury
authors.forename: Peter
authors.initials: P
authors.lastname: Burger