Cationic Hydrogen Complexes of Rhenium. 2. Synthesis, Reactivity, and Competition Studies

D. M. Heinekey,* Catherine E. Radzewich, Mark H. Voges, and Beth M. Schomber
Contribution from the Department of Chemistry, Box 351700, University of Washington, Seattle, Washington 98195-1700
J. Am. Chem. Soc., 1997, 119 (18), pp 4172–4181
DOI: 10.1021/ja9643228
Publication Date (Web): May 7, 1997
Copyright © 1997 American Chemical Society
*

In papers with more than one author, the asterisk indicates the name of the author to whom inquiries about the paper should be addressed.

Abstract

Cationic rhenium dihydrogen complexes, [Re(H2)(PR3)2(CO)3]B(Ar‘)4 (PR3 = PCy3, PiPr3, PiPrPh2, PPh3; Ar‘ = 3,5-(CF3)2C6H3), have been prepared by the protonation of ReX(PR3)2(CO)3 (X = H, CH3) with [H(Et2O)2]B(Ar‘)4 under a hydrogen atmosphere. Deuterium is incorporated into the H2 ligand when placed under a D2 atmosphere and large JHD values (30−33 Hz) are consistent with a dihydrogen formulation. Relaxation data indicate very short T1min for these complexes. These complexes are susceptible to heterolytic cleavage of dihydrogen, and the reactivity with several bases has been investigated. Under vacuum or argon atmosphere the complexes readily lose hydrogen to form 16-electron complexes. In the solid state, [Re(PCy3)2(CO)3]B(Ar‘)4 exhibits an agostic interaction to a β C−H bond of the phosphine ligand. Variable-temperature 31P{1H} NMR spectra of [Re(PCy3)2(CO)3]B(Ar‘)4 indicate a dynamic process involving hindered rotation about the Re−P bond. Competition studies have been conducted, and the hydrogen binding affinity is higher for [Re(H2)(PCy3)2(CNtBu)3]B(Ar‘)4 (5) than for [Re(H2)(PCy3)2(CO)3]B(Ar‘)4 (2a). Similar experiments also find that 5 also binds hydrogen preferentially over W(H2)(PCy3)2(CO)3.

View: Full Text HTML | Hi-Res PDF

Tools

History

  • Published In Issue May 07, 1997
  • Received December 16, 1996

Recommend & Share

Related Content

Other ACS content by these authors: