Estimating the Wavenumber of Terminal Metal-Hydride Stretching Vibrations of Octahedral d⁶ Transition Metal Complexes

Abstract

The wavenumbers of 774 terminal hydride infrared active stretching modes of 478 distinct classes of structures of d6 octahedral complexes of Mn­(I), Re­(I), Fe­(II), Ru­(II), Os­(II), Co­(III), Rh­(III), Ir­(III), and Pt­(IV) were collected from the literature. A fair correlation (R 2 0.95 with standard deviation 31 cm–1) is found for the data with the equation νMH calc = ν0 + Δν t + Δν n , where ν0 is the base wavenumber for the metal ion in question, Δν t is the parameter of influence of the ligand trans to the hydride, and Δν n is a correction for the charge of the complex [MHL5] n+. The introduction of a cis influence parameter has little effect on the correlation, showing that the trans influence dominates in this case. The equation is useful in identifying anomalous data reported in the literature, validating future assignments of νMH, understanding better metal-hydride bonding, and possibly assisting in identifying superior hydride-based catalysts.

Photo‐Initiated Cobalt‐Catalyzed Radical Olefin Hydrogenation

“…The CoÀ H stretching frequency of 1 (ν = 1756 cm À 1 ; Δν H/D = 487 cm À 1 ), ranges at the lower end when compared with other neutral cobalt(II) pincer hydride complexes (~1820-2030 cm À 1 ), [3I,18] reflecting a large trans-influence of the divinylamide ligand. [19] The three paramagnetically shifted and broadened solution 1 Scheme 1. Hydrogen activation by the cobalt pincer platform reported by Choi and Lee.…”

Oxidative Addition of Secondary Phosphine Oxides through Rh(I) Center: Hydrido‐Phosphinito‐Rh(III) Complexes and their Catalytic Activity in Hydrophosphinylation of Alkynes

“…The IR spectra show a stretching in the ν(P=O) range, in the 1094 to 1098 cm −1 range. The band due to ν(Rh−H) appears as expected for a rhodium‐bonded hydride trans to bipyridine, [21] but for complexes 1 d and 1 e , appearing at higher frequency, 2195 and 2166 cm −1 , respectively. A correlation frequently observed in transition metal hydrides [24] is thus found between δ(Rh−H) and ν(Rh−H), which could indicate a lower σ‐donor strength of the bulkier ligands.…”

“…for [M−Cl] + 663.08) and suggests 1 a to be a mononuclear hexacoordinated 18e species. The IR spectrum shows a band at 2081 cm −1 due to ν(Rh−H), in the range expected for a hydride trans to bipyridine [21] and a stretching at 1097 cm −1 , in the ν(P=O) range [22] . Compound 1 a was also characterized by single crystal X‐ray structural determination (Figure 1).…”

NNN Pincer‐functionalized Porous Organic Polymer Supported Ru(III) as a Heterogeneous Catalyst for Levulinic Acid Hydrogenation to γ‐Valerolactone

“…In addition, the IR spectrum of the spent catalyst was almost identical to that of the fresh catalyst, confirming high robustness of the catalyst support. Importantly, the freshly emerged peak at 1960 cm −1 for the spent catalyst indicates the generation of a Ru‐hydride species during hydrogenation (Figure 5c), which was stable under ambient conditions also [76,77] . The porosity of the spent catalyst was also evaluated with N 2 adsorption‐desorption analysis at 77 K. The porosity of the catalyst was very similar to that of the fresh catalyst, indicating that no structural degradation or decomposition of the support occurred during hydrogenation (Figure 5d).…”

“…Importantly, the freshly emerged peak at 1960 cm À 1 for the spent catalyst indicates the generation of a Ru-hydride species during hydrogenation (Figure 5c), which was stable under ambient conditions also. [76,77] The porosity of the spent catalyst was also evaluated with N 2 adsorption-desorption analysis at 77 K. The porosity of the catalyst was very similar to that of the fresh catalyst, indicating that no structural degradation or decomposition of the support occurred during hydrogenation (Figure 5d). However, in a 24 hterm catalyst recycling test, a decrease in catalytic activity was observed, reaching a TON of 9718 in the third cycle ( Figure 4b and Table S3).…”