Assessment of the "T1 criterion" for distinguishing between classical and nonclassical transition-metal hydrides: hydride relaxation rates in tris(triarylphosphine)osmium tetrahydrides and related polyhydrides

Selective B–H versus N–H Bond Activation in Ammonia Borane by [Ir(dppm)2]OTf

“…No boron-containing species was present, as shown by the absence of 11 B NMR signals. The classical dihydrides 2 (T 1min = 490.4 ms, 257 K; 566.2 ms, 308 K for 2a and 2b, respectively) [21][22][23][24] were also obtained independently by gently bubbling H 2 ( A small amount of dark precipitate was formed during the reaction and was found to be insoluble in most common organic solvents and poorly soluble in polar solvents such as dmso and MeCN. Preliminary 11 B NMR and IR analyses suggest the formation of (poly)borane derivatives.…”

Activation of Hydrogen by Palladium(0): Formation of the Mononuclear Dihydride Complextrans‐[Pd(H)2(IPr)(PCy3)]

“…Dihydrides and dihydrogen complexes can be distinguished by their minimum T 1 value, by following the method of Halpern and coworkers. [17] This method is not straightforward when multiple nuclei contribute to the overall relaxation rate, defined as R (R=1/T 1 ). For complex 2, the contributions of the phosphorus atom and the other H atoms present in the molecule have to be considered.…”

Solvent‐Dependent Dihydrogen/Dihydride Stability for [Mo(CO)(Cp*)H2(PMe3)2]+[BF4]− Determined by Multiple Solvent⋅⋅⋅Anion⋅⋅⋅Cation Non‐Covalent Interactions

“…This is suggested by the broad shape of the hydride resonance at d = À5.14 ppm in the 1 H NMR spectrum and confirmed by the low T 1 min value of 24 ms at 190 K (500 MHz). Application of the method of Halpern and co-workers gives an HÀH length of 1.1 in the slow rotation regime, [24] or 0.88 in the fast rotation regime. [25] Other selected NMR and IR spectroscopic properties of this compound can be found in Table 1, together with those of the starting material (the complete characterisation is provided in the Supporting Information).…”