Effects of ancillary ligands in acceptorless benzyl alcohol dehydrogenation mediated by phosphine-free cobalt complexes
Yan Xu1, Lu Wang1,3, Junwei Wu1, Guanzhong Zhai1, Daohua Sun1,2()
1. Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China 2. Department of Chemical and Biochemical Engineering, National Engineering Laboratory for Green Chemical Productions of Alcohols−Ethers−Esters, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China 3. Luoyang Ship Material Institute, Luoyang 471039, China
Acceptorless alcohol dehydrogenation stands out as one of the most promising strategies in hydrogen storage technologies. Among various catalytic systems for this reaction, cost-effective molecular catalysts using phosphine-free ligands have gained considerable attention. However, the central challenge for using non-precious metals is to overcome the propensity of reacting by one-electron pathway. Herein, we synthesized a phosphine-free η5-C5Me5-Co complex by using the metal–ligand cooperative strategy and compared its activity with analogous catalysts toward acceptorless alcohol dehydrogenation. The catalyst showed excellent performance with a turnover number of 130.4 and a selectivity close to 100%. The improved performance among the class of η5-C5Me5-Co complexes could be attributed to the more accessible Co center and its cooperation with the redox-active ligand. To further study the systematic structure-activity relationship, we investigated the electronic structures of η5-C5Me5-Co complexes by a set of characterizations. The results showed that the redox-active ligand has a significant influence on the η5-C5Me5-Co moiety. In the meantime, the proximal O−/OH group is beneficial for shuttling protons. For the catalytic cycle, two dehydrogenation scenarios were interrogated through density functional theory, and the result suggested that the outer-sphere pathway was preferred. The formation of a dihydrogen complex was the rate-determining step with a ΔG value of 16.9 kcal∙mol‒1. The electron population demonstrated that the η5-C5Me5 ligand played a key role in stabilizing transition states during dehydrogenation steps. This work identified the roles of vital ligand components to boost catalytic performance and offered rationales for designing metal–ligand cooperative nonprecious metal complexes.
T Schaub, M Trincado, H Grützmacher. Hydrogen Storage: Based on Hydrogenation and Dehydrogenation Reactions of Small Molecules. Berlin: Walter de Gruyter GmbH & Co KG, 2019,
2
C Gunanathan, D Milstein. Applications of acceptorless dehydrogenation and related transformations in chemical synthesis. Science, 2013, 341(6143): 1229712 https://doi.org/10.1126/science.1229712
3
A K Bains, Y Ankit, D Adhikari. Bioinspired radical-mediated transition-metal-free synthesis of N-heterocycles under visible light. ChemSusChem, 2021, 14(1): 324–329 https://doi.org/10.1002/cssc.202002161
4
S Budweg, K Junge, M Beller. Catalytic oxidations by dehydrogenation of alkanes, alcohols and amines with defined (non)-noble metal pincer complexes. Catalysis Science & Technology, 2020, 10(12): 3825–3842 https://doi.org/10.1039/D0CY00699H
5
K Sarkar, K Das, A Kundu, D Adhikari, B Maji. Phosphine-free manganese catalyst enables selective transfer hydrogenation of nitriles to primary and secondary amines using ammonia-borane. ACS Catalysis, 2021, 11(5): 2786–2794 https://doi.org/10.1021/acscatal.0c05406
6
M Valencia, H Muller-Bunz, R A Gossage, M Albrecht. Enhanced product selectivity promoted by remote metal coordination in acceptor-free alcohol dehydrogenation catalysis. Chemical Communications, 2016, 52(16): 3344–3347 https://doi.org/10.1039/C6CC00267F
7
T J Mazzacano, N P Mankad. Base metal catalysts for photochemical C–H borylation that utilize metal-metal cooperativity. Journal of the American Chemical Society, 2013, 135(46): 17258–17261 https://doi.org/10.1021/ja408861p
8
C Hou, Z Zhang, C Zhao, Z Ke. DFT study of acceptorless alcohol dehydrogenation mediated by ruthenium pincer complexes: ligand tautomerization governing metal ligand cooperation. Inorganic Chemistry, 2016, 55(13): 6539–6551 https://doi.org/10.1021/acs.inorgchem.6b00723
9
D R Pradhan, S Pattanaik, J Kishore, C Gunanathan. Cobalt-catalyzed acceptorless dehydrogenation of alcohols to carboxylate salts and hydrogen. Organic Letters, 2020, 22(5): 1852–1857 https://doi.org/10.1021/acs.orglett.0c00193
10
D Lupp, K W Huang. The importance of metal–ligand cooperativity in the phosphorus-nitrogen PN3P platform: a computational study on Mn-catalyzed pyrrole synthesis. Organometallics, 2019, 39(1): 18–24 https://doi.org/10.1021/acs.organomet.9b00102
11
K Fujita, R Tamura, Y Tanaka, M Yoshida, M Onoda, R Yamaguchi. Dehydrogenative oxidation of alcohols in aqueous media catalyzed by a water-soluble dicationic iridium complex bearing a functional N-heterocyclic carbene ligand without using base. ACS Catalysis, 2017, 7(10): 7226–7230 https://doi.org/10.1021/acscatal.7b02560
12
L V A Hale, N K Szymczak. Hydrogen transfer catalysis beyond the primary coordination sphere. ACS Catalysis, 2018, 8(7): 6446–6461 https://doi.org/10.1021/acscatal.7b04216
13
U Hintermair, J Campos, T P Brewster, L M Pratt, N D Schley, R H Crabtree. Hydrogen-transfer catalysis with Cp*Ir(III) complexes: the influence of the ancillary ligands. ACS Catalysis, 2013, 4(1): 99–108 https://doi.org/10.1021/cs400834q
14
M C Lehman, J B Gary, P D Boyle, M S Sanford, E A Ison. Effect of solvent and ancillary ligands on the catalytic H/D exchange reactivity of Cp*Ir(III)(L) complexes. ACS Catalysis, 2013, 3(10): 2304–2310 https://doi.org/10.1021/cs400420n
15
G Zeng, S Sakaki, K Fujita, H Sano, R Yamaguchi. Efficient catalyst for acceptorless alcohol dehydrogenation: interplay of theoretical and experimental studies. ACS Catalysis, 2014, 4(3): 1010–1020 https://doi.org/10.1021/cs401101m
16
R Kawahara, K Fujita, R Yamaguchi. Cooperative catalysis by iridium complexes with a bipyridonate ligand: versatile dehydrogenative oxidation of alcohols and reversible dehydrogenation–hydrogenation between 2-propanol and acetone. Angewandte Chemie International Edition, 2012, 51(51): 12790–12794 https://doi.org/10.1002/anie.201206987
17
N Johnee Britto, A S Rajpurohit, K Jagan, M Jaccob. Unravelling the reaction mechanism of formic acid dehydrogenation by Cp*Rh(III) and Cp*Co(III) catalysts with proton-responsive 4,4′- and 6,6′-dihydroxy-2,2′-bipyridine ligands: a DFT study. Journal of Physical Chemistry C, 2019, 123(41): 25061–25073 https://doi.org/10.1021/acs.jpcc.9b05880
18
D B Burks, M Vasiliu, D A Dixon, E T Papish. Thermodynamic acidity studies of 6,6′-dihydroxy-2,2′-bipyridine: a combined experimental and computational approach. Journal of Physical Chemistry A, 2018, 122(8): 2221–2231 https://doi.org/10.1021/acs.jpca.7b11441
19
W H Wang, J T Muckerman, E Fujita, Y Himeda. Mechanistic insight through factors controlling effective hydrogenation of CO2 catalyzed by bioinspired proton-responsive iridium(III) complexes. ACS Catalysis, 2013, 3(5): 856–860 https://doi.org/10.1021/cs400172j
20
Y Zhao, D G Truhlar. Density functionals with broad applicability in chemistry. Accounts of Chemical Research, 2008, 41(2): 157–167 https://doi.org/10.1021/ar700111a
21
P J Hay, W R Wadt. Ab initio effective core potentials for molecular calculations. Potentials for the transition metal atoms Sc to Hg. Journal of Chemical Physics, 1985, 82(1): 270–283 https://doi.org/10.1063/1.448799
22
W R Wadt, P J Hay. Ab initio effective core potentials for molecular calculations. Potentials for main group elements Na to Bi. Journal of Chemical Physics, 1985, 82(1): 284–298 https://doi.org/10.1063/1.448800
23
W J Hehre, R Ditchfield, J A Pople. Self-consistent molecular orbital methods. XII. Further extensions of Gaussian-type basis sets for use in molecular orbital studies of organic molecules. Journal of Chemical Physics, 1972, 56(5): 2257–2261 https://doi.org/10.1063/1.1677527
24
H B Schlegel. Optimization of equilibrium geometries and transition structures. Journal of Computational Chemistry, 1982, 3(2): 214–218 https://doi.org/10.1002/jcc.540030212
25
V S Bryantsev, M S Diallo, W A III Goddard. Calculation of solvation free energies of charged solutes using mixed cluster/continuum models. Journal of Physical Chemistry B, 2008, 112(32): 9709–9719 https://doi.org/10.1021/jp802665d
26
C P Kelly, C J Cramer, D G Truhlar. Aqueous solvation free energies of ions and ion-water clusters based on an accurate value for the absolute aqueous solvation free energy of the proton. Journal of Physical Chemistry B, 2006, 110(32): 16066–16081 https://doi.org/10.1021/jp063552y
27
A E Reed, L A Curtiss, F Weinhold. Intermolecular interactions from a natural bond orbital, donor−acceptor viewpoint. Chemical Reviews, 1988, 88(6): 899–926 https://doi.org/10.1021/cr00088a005
28
T Avilés, A Dinis, Gonçalves J Orlando, V Félix, M J Calhorda, Â Prazeres, M G B Drew, H Alves, R T Henriques, V Gama, P Zanello, M Fontani. Synthesis, X-ray structures, electrochemistry, magnetic properties, and theoretical studies of the novel monomeric [CoI2(dppfO2)] and polymeric chain. Dalton Transactions, 2002, (24): 4595–4602 https://doi.org/10.1039/B205942H
29
M Nielsen, E Alberico, W Baumann, H J Drexler, H Junge, S Gladiali, M Beller. Low-temperature aqueous-phase methanol dehydrogenation to hydrogen and carbon dioxide. Nature, 2013, 495(7439): 85–89 https://doi.org/10.1038/nature11891
30
Y M Badiei, W H Wang, J F Hull, D J Szalda, J T Muckerman, Y Himeda, E Fujita. Cp*Co(III) catalysts with proton-responsive ligands for carbon dioxide hydrogenation in aqueous media. Inorganic Chemistry, 2013, 52(21): 12576–12586 https://doi.org/10.1021/ic401707u
31
P Sanchez, M Hernandez-Juarez, N Rendon, J Lopez-Serrano, L L Santos, E Alvarez, M Paneque, A Suarez. Hydrogenation/dehydrogenation of N-heterocycles catalyzed by ruthenium complexes based on multimodal proton-responsive CNN(H) pincer ligands. Dalton Transactions, 2020, 49(28): 9583–9587 https://doi.org/10.1039/D0DT02326D
