| Abstract
| - Mixtures of deuterium labeled complexes (p-XPOCOP)IrH2-xDx (1−6-d0-2) {POCOP = [C6H2-1,3-[OP(tBu)2]2}; X = MeO (1), Me (2), H (3), F (4), C6F5 (5), and ArF = 3,5-(CF3)2-C6H3 (6)} have beengenerated by reaction of (p-XPOCOP)IrH2 complexes with HD gas in benzene followed by removal of thesolvent under high vacuum. Spectroscopic analysis employing 1H and 2D NMR reveals significanttemperature and solvent dependent isotopic shifts and HD coupling constants. Complexes 1−6-d1 in tolueneand pentane between 296 and 213 K exhibit coupling constants JHD of 3.8−9.0 Hz, suggesting the presenceof an elongated H2 ligand, which is confirmed by T1(min) measurements of complexes 1, 3, and 6 in toluene-d8. In contrast, complex 6-d1 exhibits JHD = 0 Hz in CH2Cl2 or CDCl2F whereas isotopic shifts up to −4.05ppm have been observed by lowering the temperature from 233 to 133 K in CDCl2F. The large andtemperature-dependent isotope effects are attributed to nonstatistical occupation of two different hydrideenvironments. The experimental observations are interpreted in terms of a two component model involvingrapid equilibration of solvated Ir(III) dihydride and Ir(I) dihydrogen structures.
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