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Article

Structure and Dynamics of a Compressed Dihydride Complex of Osmium

Nils Schloerer,^† Vincent Pons,^† Dmitry G. Gusev,*^‡ and D. Michael Heinekey*^†

Departments of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, and Wilfred Laurier University, Waterloo, Ontario N2L 3C5, Canada

Organometallics, 2006, 25 (14), pp 3481–3485

DOI: 10.1021/om060284h

Publication Date (Web): May 25, 2006

†

University of Washington.

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

‡

Wilfred Laurier University.

Abstract

The complex OsCl(NHC(Ph)C₆H₄)(PiPr₃)₂(H₂) (1) has been characterized by Esteruelas and co-workers (Organometallics 1998, 17, 4065−4076) as an elongated dihydrogen complex based on relaxation time measurements and observation of J_H_-_D = 6.3 Hz in 1-d₁. Variable-temperature NMR studies were reported in which the single hydride resonance observed at ambient temperature decoalesced into two signals at low temperature (193 K), which was attributed to hindered rotation of the bound H₂ ligand. Reinvestigation of the low-temperature NMR spectra of 1 reveals a more complex situation. Examination of the ¹H and ³¹P NMR spectra of 1 and 1-d₁ at lower temperatures than previously studied demonstrates that quantum mechanical exchange coupling is observed between the metal-bonded hydrogen atoms. This coupling is quenched in 1-d₁. Hindered rotation around Os−P bonds in 1 also contributes to the observed NMR spectra.