Solid-State Chemistry of Molecular Metal Oxide Clusters. Ortho Metalation and Hydrogen Transport in 3PW12O40 Probed by 31P NMR Long-Range Deuterium Isotope Effects

Article abstract of DOI:10.1021/ja00188a017

Deuterium isotope effects on ³¹P shielding that are large relative to the accuracy with which they can be measured are reported.In (Ph3P)2IrH2(dmf)2⁺, substitution of one ²H for ¹H at the IR-H or at the ortho position in the Ph3P ligand leads to two- and three-bond isotope shifts of +0.094 and -0.110 ppm, respectively, with the effect being defined as <δ(²H form)-δ(¹H form)>.The ortho-deuterium effects on ³¹P for Ph3P, Ph3PO, Ph3PMe⁺I^-, and (Ph3P)2Ir(C8H12)⁺ are -0.110, -0.096, -0.035, and -0.077 ppm, respectively.These long-range isotope effects are used to demonstrate a thermally activated, solid-state exchange of deuterium between iridium and only in the ortho positions of the Ph3P ligands in <(Ph3P)2IrH2>3PW12O40.There occurs, additionally, an intermolecular hydrogen-deuterium exchange process.Slow exchange with c-C6D12 leads to incorporation of the deuterium label in the Ph3P rings.