The hangman effect boosts hydrogen production by a manganese terpyridine complex

Abstract

A manganese terpyridine complex 1 with a coordinated carboxylate in the axial position was obtained in situ. By virtue of a hangman effect, complex 1 catalyzes electrochemical hydrogen evolution from...

Exploring the Parameters Controlling Product Selectivity in Electrochemical CO2 Reduction in Competition with Hydrogen Evolution Employing Manganese Bipyridine Complexes

“…This is in accordance with a high-overpotential pathway, in which the hydride species 4 is reduced and subsequently enters the catalytic cycle . The trace crossing in Figure and Figures S3 and S4 indicates an acceleration of the catalytic behavior on the reverse scan (see Section 5 in the Supporting Information for a detailed explanation) . The specific catalytic effect of residual water (∼0.034 M) in combination with CO 2 (Figure ) is discussed thoroughly in Section 6 of the Supporting Information.…”

“… 9 The trace crossing in Figure 4 and Figures S3 and S4 indicates an acceleration of the catalytic behavior on the reverse scan (see Section 5 in the Supporting Information for a detailed explanation). 39 The specific catalytic effect of residual water (∼0.034 M) in combination with CO 2 ( Figure 4 ) is discussed thoroughly in Section 6 of the Supporting Information. Upon sequential addition of either 2,2,2-trifluoroethanol (TFE, p K a = 35.4 in MeCN, 40 Figure S7 ) or 2-propanol ( i PrOH, p K a ≈ 42 in MeCN, 37 Figure S8 ), the catalytic current continues increasing, until it levels off or even drops once very high concentrations of TFE (2.0 M) or i PrOH (1.0 M) are employed.…”

Proton Tunneling Distances for Metal Hydrides Formation Manage the Selectivity of Electrochemical CO2 Reduction Reaction

“…CV of complex 2 p reveals a reversible couple at −1.55 V with a peak to peak separation of 48 mV (Figure 5a). Based on the IR‐SEC studies of 2 p (black line, Figure 5b) and our previous study in the analogues, [13] complex 2 p undergoes a coordination switch from k 2 ‐N,N′,N′′‐tpy (k 2 ‐tpy, 2023, 1934, and 1916 cm −1 ) to k 3 ‐N,N′,N′′‐tpy (k 3 ‐tpy, 1946, 1927, 1877, and 1856 cm −1 , red line, Figure 5b) prior to the redox event, and eventually fully transforms to 2 transforms to 2 . Maintaining the potential at −1.55 V, the in situ generated complex 2 behaviors two successive one‐electron reduction and results in a doubly reduced species [ 2 2 − −Br − ] featuring two absorption bands at 1838 and 1772 cm −1 [14] .…”

“…CV of complex 2 p reveals a reversible couple at À 1.55 V with a peak to peak separation of 48 mV (Figure 5a). Based on the IR-SEC studies of 2 p (black line, Figure 5b) and our previous study in the analogues, [13] complex 2 p undergoes a coordination switch from k 2 -N,N',N''-tpy (k 2 -tpy, 2023, 1934, and 1916 cm À 1 ) to k 3 -N,N',N''-tpy (k 3 -tpy, 1946, 1927, 1877,…”

Effects of proton tunneling distance on CO2 reduction by Mn terpyridine species

“…Initially, we obtained two precursors 1p and 2p and a control complex 3 by refluxing [MnBr(CO) 5 ] with the corresponding ligands in methanol for 3 hours under dark conditions (Schemes S1-S6 †). 13 These complexes were unambiguously characterized by FTIR, 1 H NMR, high-resolution mass spectroscopy (HR-MS) and elemental analyses (Fig. S1-S10 †).…”