Cobalt(II) and Nickel(II) Complexes of a PNN Type Ligand as Photoenhanced Electrocatalysts for the Hydrogen Evolution Reaction

Abstract

Hydrogen will be an important energy vector of the future, and improved efficiency in electrohydrolysis will accelerate this transition. In a fundamental study, we have prepared Co­(II) and Ni­(II) complexes of a new PNN type ligand N-((diphenylphosphanyl)­methyl)-2-amino-1,10-phenanthroline (dppmaphen) incorporating the photoactive 1,10-phenanthroline group and the strongly coordinating diphenylphosphine to obtain photoelectrochemical (PEC) catalysts [Co­(dppmaphen)2(NO3)2] (1) and [Ni­(dppmaphen)2Cl]Cl (2) which catalyzed the hydrogen evolution reaction (HER) in alkaline media (1 M KOH). Overpotentials (η10) of 430 (1) and 364 mV (2) could be reduced to 345 (1) and 284 mV (2) under Xe light irradiation. This irradiation generated photocurrent responses of 528 (1) and 357 uA/cm2 (2). Density function theory (DFT) calculation on the frontier orbitals of 1 and 2 were useful in understanding these differences in catalytic performance.

Phospha-Mannich reactions of RPH2, R2PH, and R3P

“…Ar' Ar Yield, % d P , ppm 77 [209,210] -18.5 (CDCl 3 ) 48 [211] -20.4 (CDCl 3 ) 59, [210] 79, [212] 95 [213] -17.4 (DMSO-d 6 ), -18.1 (CDCl 3 ), -18.5 (CDCl 3 ) 87 [212] -16.8 (DMSO-d 6 ) 87 [214] -17.4 (CDCl 3 ) 88 [215] -18.1 (CDCl 3 ) 60 [215] -19.3 (CDCl 3 ) 59, [216] 71, [217] 78 [218] -18.9 (CDCl 3 ), -19.4 (CDCl 3 ), -22.2 (DMSO-d 6 ) 64, [219] 93 [220] -17.1 (CDCl 3 ) 61 [221] -17.2 (CDCl 3 ) 87 [222] -18.6 (CDCl 3 ) 37 [223] -17.8 (CD 2 Cl 2 ) 23 [143] -19.6 (CDCl 3 ) 93 [210] -18.8 (CDCl 3 ) 51 [148] -33.2 (CDCl 3 ) 73 [148] -31.7 (CDCl 3 )…”

Low-Dimensional Architectures in Isomeric cis-PtCl2{Ph2PCH2N(Ar)CH2PPh2} Complexes Using Regioselective-N(Aryl)-Group Manipulation

“…We [11][12][13][14][15][16]29], and others [17,[19][20][21][22], have previously used Mannich condensations as a versatile method for the synthesis of aminomethylphosphines. Accordingly, two equivalents of Ph 2 PCH 2 OH were reacted with one equivalent of the amine, for 24 h at r.t. under N 2 , yielding the desired phenol-substituted ditertiary phosphines 1a-e and 3 (Scheme 1).…”

“…For a number of years, we [11][12][13][14][15][16], and others [17][18][19][20][21][22], have been interested in aminomethylphosphines, readily amenable by Mannich condensation reactions. Such interest stems from the relative ease of accessing P-monodentate ligands based on a P-C-N linker [11,15,16,19,20,22] or P/P-bidentate derivatives bearing a P-C-N-C-P backbone [12][13][14][17][18][19]21]. Previously, we have shown that the N-arene group can be easily tuned with, for example, various H-bonding donor/acceptor sites based on -CO 2 H/OH groups [12][13][14][15][16].…”

Mild intramolecular P–C(sp3) bond cleavage in bridging diphosphine complexes of RuII RhIII and IrIII

“…Chelating diphosphines are widely used in transition metal chemistry and can also be susceptible to thermal/chemical induced P−C bond activation at one (or more) metal centres [5]. We [6], and others [7,8],…”