1
|
Duman S, Özhava D. Green Approaches to Dehydrogenation of DMAB Catalyzed by Starch Stabilized Ru(0), Cu(0) and Ni(0) Nanoparticles in the Absence of a Solvent. ChemistrySelect 2023. [DOI: 10.1002/slct.202204606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- Sibel Duman
- Department of Chemistry Bingol University 12000 Bingol Türkiye
| | - Derya Özhava
- Department of Chemistry and Chemical Processing Technologies Cumra Vocational School Selcuk University 42130 Konya Türkiye
| |
Collapse
|
2
|
Peng C, Liu W, Wang Y. Mechanistic insights into H 3B·NMeH 2 dehydrogenation by Co-based complexes: a DFT perspective. NEW J CHEM 2023. [DOI: 10.1039/d2nj06155d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/17/2023]
Abstract
Mechanistic insights into Co-catalyzed H3B·NMeH2 dehydrogenation and polyaminoborane formation are carefully investigated using density functional theory.
Collapse
Affiliation(s)
- Cheng Peng
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, P. R. China
| | - Wei Liu
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, P. R. China
| | - Yong Wang
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, P. R. China
| |
Collapse
|
3
|
Brodie CN, Sotorrios L, Boyd TM, Macgregor SA, Weller AS. Dehydropolymerization of H 3B·NMeH 2 Mediated by Cationic Iridium(III) Precatalysts Bearing κ 3- iPr-PN RP Pincer Ligands ( R = H, Me): An Unexpected Inner-Sphere Mechanism. ACS Catal 2022; 12:13050-13064. [PMID: 36313521 PMCID: PMC9594342 DOI: 10.1021/acscatal.2c03778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 09/27/2022] [Indexed: 11/30/2022]
Abstract
![]()
The dehydropolymerization of H3B·NMeH2 to form N-methylpolyaminoborane using neutral
and
cationic catalysts based on the {Ir(iPr-PNHP)} fragment [iPr-PNHP = κ3-(CH2CH2PiPr2)2NH] is reported. Neutral
Ir(iPr-PNHP)H3 or
Ir(iPr-PNHP)H2Cl
precatalysts show no, or poor and unselective, activity respectively
at 298 K in 1,2-F2C6H4 solution.
In contrast, addition of [NMeH3][BArF4] (ArF = 3,5-(CF3)2C6H3) to Ir(iPr-PNHP)H3 immediately starts catalysis, suggesting that a cationic
catalytic manifold operates. Consistent with this, independently synthesized
cationic precatalysts are active (tested between 0.5 and 2.0 mol %
loading) producing poly(N-methylaminoborane) with Mn ∼ 40,000 g/mol, Đ ∼1.5, i.e., dihydrogen/dihydride, [Ir(iPr-PNHP)(H)2(H2)][BArF4]; σ-amine-borane [Ir(iPr-PNHP)(H)2(H3B·NMe3)][BArF4]; and [Ir(iPr-PNHP)(H)2(NMeH2)][BArF4]. Density functional theory (DFT) calculations
probe hydride exchange processes in two of these complexes and also
show that the barrier to amine-borane dehydrogenation is lower (22.5
kcal/mol) for the cationic system compared with the neutral system
(24.3 kcal/mol). The calculations show that the dehydrogenation proceeds
via an inner-sphere process without metal–ligand cooperativity,
and this is supported experimentally by N–Me substituted [Ir(iPr-PNMeP)(H)2(H3B·NMe3)][BArF4] being
an active catalyst. Key to the lower barrier calculated for the cationic
system is the outer-sphere coordination of an additional H3B·NMeH2 with the N–H group of the ligand.
Experimentally, kinetic studies indicate a complex reaction manifold
that shows pronounced deceleratory temporal profiles. As supported
by speciation and DFT studies, a key observation is that deprotonation
of [Ir(iPr-NHP)(H)2(H2)][BArF4], formed upon amine-borane
dehydrogenation, by the slow in situ formation of NMeH2 (via B–N bond cleavage), results in the formation of essentially
inactive Ir(iPr-PNHP)H3, with a coproduct of [NMeH3]+/[H2B(NMeH2)2]+. While reprotonation
of Ir(iPr-PNHP)H3 results in a return to the cationic cycle, it is proposed, supported
by doping experiments, that reprotonation is attenuated by entrainment
of the [NMeH3]+/[H2B(NMeH2)2]+/catalyst in insoluble polyaminoborane.
The role of [NMeH3]+/[H2B(NMeH2)]+ as chain control agents is also noted.
Collapse
Affiliation(s)
| | - Lia Sotorrios
- Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K
| | - Timothy M. Boyd
- Department of Chemistry, University of York, York YO10 5DD, U.K
- Chemistry Research Laboratories, University of Oxford, Oxford OX1 3TA, U.K
| | - Stuart A. Macgregor
- Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K
| | | |
Collapse
|
4
|
Linke A, Decker D, Drexler HJ, Beweries T. Iridium(III) bis(thiophosphinite) pincer complexes: synthesis, ligand activation and applications in catalysis. Dalton Trans 2022; 51:10266-10271. [PMID: 35748648 DOI: 10.1039/d2dt01633h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Iridium(III) bis(thiophosphinite) complexes of the type [(RPSCSPR)Ir(H)(Cl)(py)] (RPSCSPR = κ3-(2,6-SPR2)C6H3) (R = tBu, iPr, Ph) can be prepared from the ligand precursors 1,3-(SPR2)C6H4 by C-H activation at Ir using [Ir(COE)2Cl]2 or [Ir(COD)Cl]2. Optimisation of the protocol for complexation showed that direct cyclometallation in the absence or presence of pyridine, as well as C-H activation in the presence of H2 are viable options that, depending on the phosphine substituent furnish the five-coordinate Ir(III) hydride chloride complexes 2-R or the base stabilised species 3-R in good yields. In case of the PhPSCSPPh ligand, P-S activation results in the formation of a thiophosphine stabilised Ir(III) hydride complex [(PhPSCSPPh)Ir(H)(Cl)(PPh2SH)] (4). Reaction of 2-tBu with H2 in the presence of base furnishes an Ir(III) dihydride complex (5) via a labile Ir(III) dihydride-dihydrogen complex (6). All complexes are inactive for transfer dehydrogenation of cyclooctane in the presence of NaOtBu and tert-butylethylene, likely due to decomposition of the Ir complex in the presence of base at higher temperature.
Collapse
Affiliation(s)
- Alexander Linke
- Leibniz-Institut für Katalyse e.V., Albert-Einstein-Str. 29a, 18059 Rostock, Germany.
| | - David Decker
- Leibniz-Institut für Katalyse e.V., Albert-Einstein-Str. 29a, 18059 Rostock, Germany.
| | - Hans-Joachim Drexler
- Leibniz-Institut für Katalyse e.V., Albert-Einstein-Str. 29a, 18059 Rostock, Germany.
| | - Torsten Beweries
- Leibniz-Institut für Katalyse e.V., Albert-Einstein-Str. 29a, 18059 Rostock, Germany.
| |
Collapse
|
5
|
Brodie CN, Boyd TM, Sotorríos L, Ryan DE, Magee E, Huband S, Town JS, Lloyd-Jones GC, Haddleton DM, Macgregor SA, Weller AS. Controlled Synthesis of Well-Defined Polyaminoboranes on Scale Using a Robust and Efficient Catalyst. J Am Chem Soc 2021; 143:21010-21023. [PMID: 34846131 DOI: 10.1021/jacs.1c10888] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The air tolerant precatalyst, [Rh(L)(NBD)]Cl ([1]Cl) [L = κ3-(iPr2PCH2CH2)2NH, NBD = norbornadiene], mediates the selective synthesis of N-methylpolyaminoborane, (H2BNMeH)n, by dehydropolymerization of H3B·NMeH2. Kinetic, speciation, and DFT studies show an induction period in which the active catalyst, Rh(L)H3 (3), forms, which sits as an outer-sphere adduct 3·H3BNMeH2 as the resting state. At the end of catalysis, dormant Rh(L)H2Cl (2) is formed. Reaction of 2 with H3B·NMeH2 returns 3, alongside the proposed formation of boronium [H2B(NMeH2)2]Cl. Aided by isotopic labeling, Eyring analysis, and DFT calculations, a mechanism is proposed in which the cooperative "PNHP" ligand templates dehydrogenation, releasing H2B═NMeH (ΔG‡calc = 19.6 kcal mol-1). H2B═NMeH is proposed to undergo rapid, low barrier, head-to-tail chain propagation for which 3 is the catalyst/initiator. A high molecular weight polymer is formed that is relatively insensitive to catalyst loading (Mn ∼71 000 g mol-1; Đ, of ∼ 1.6). The molecular weight can be controlled using [H2B(NMe2H)2]Cl as a chain transfer agent, Mn = 37 900-78 100 g mol-1. This polymerization is suggested to arise from an ensemble of processes (catalyst speciation, dehydrogenation, propagation, chain transfer) that are geared around the concentration of H3B·NMeH2. TGA and DSC thermal analysis of polymer produced on scale (10 g, 0.01 mol % [1]Cl) show a processing window that allows for melt extrusion of polyaminoborane strands, as well as hot pressing, drop casting, and electrospray deposition. By variation of conditions in the latter, smooth or porous microstructured films or spherical polyaminoboranes beads (∼100 nm) result.
Collapse
Affiliation(s)
- Claire N Brodie
- Department of Chemistry, University of York, Heslington, York YO31 1ES, U.K
| | - Timothy M Boyd
- Department of Chemistry, University of York, Heslington, York YO31 1ES, U.K.,Department of Chemistry, University of Oxford, Oxford OX1 3TA, U.K
| | - Lia Sotorríos
- Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K
| | - David E Ryan
- Department of Chemistry, University of York, Heslington, York YO31 1ES, U.K.,Department of Chemistry, University of Oxford, Oxford OX1 3TA, U.K
| | - Eimear Magee
- International Institute for Nanocomposites Manufacturing, WMG, University of Warwick, Coventry CV4 7AL, U.K
| | - Steven Huband
- Department of Physics, University of Warwick, Coventry CV4 7AL, U.K
| | - James S Town
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
| | - Guy C Lloyd-Jones
- School of Chemistry, University of Edinburgh, Edinburgh EH9 3FJ, Scotland, U.K
| | - David M Haddleton
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, U.K
| | - Stuart A Macgregor
- Institute of Chemical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K
| | - Andrew S Weller
- Department of Chemistry, University of York, Heslington, York YO31 1ES, U.K
| |
Collapse
|
6
|
Lindenau K, Jannsen N, Rippke M, Al Hamwi H, Selle C, Drexler HJ, Spannenberg A, Sawall M, Neymeyr K, Heller D, Reiß F, Beweries T. Mechanistic insights into dehydrocoupling of amine boranes using dinuclear zirconocene complexes. Catal Sci Technol 2021. [DOI: 10.1039/d1cy00531f] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Catalytic dehydrocoupling of H3B·NMe2H using Cp2Zr(Cl)(μ-Me3SiC3SiMe3)Zr(Cl)Cp2 (1)/MeLi was studied. Spectroscopic monitoring and stoichiometric experiments show the formation and interconversion of several catalytically active Zr species.
Collapse
Affiliation(s)
| | - Nora Jannsen
- Leibniz-Institut für Katalyse e.V
- 18059 Rostock
- Germany
| | - Mirko Rippke
- Leibniz-Institut für Katalyse e.V
- 18059 Rostock
- Germany
| | | | - Carmen Selle
- Leibniz-Institut für Katalyse e.V
- 18059 Rostock
- Germany
| | | | | | - Mathias Sawall
- Institut für Mathematik
- Universität Rostock
- 18055 Rostock
- Germany
| | - Klaus Neymeyr
- Leibniz-Institut für Katalyse e.V
- 18059 Rostock
- Germany
- Institut für Mathematik
- Universität Rostock
| | - Detlef Heller
- Leibniz-Institut für Katalyse e.V
- 18059 Rostock
- Germany
| | - Fabian Reiß
- Leibniz-Institut für Katalyse e.V
- 18059 Rostock
- Germany
| | | |
Collapse
|