How general is the effect of the bulkiness of organic ligands on the basicity of metal-organic catalysts? H2-evolving Mo oxides/sulphides as case studies
Rovaletti, Anna ; Ryde, Ulf LU
; Moro, Giorgio
; Cosentino, Ugo
and Greco, Claudio
LU
(2022)
In Physical chemistry chemical physics : PCCP
24(48).
p.29471-29479
- Abstract
- Tailoring the activity of an organometallic catalyst usually requires a
targeted ligand design. Tuning the ligand bulkiness and tuning the
electronic properties are popular approaches, which are somehow
interdependent because substituents of different sizes within ligands
can determine inter alia the occurrence of different degrees of
inductive effects. Ligand basicity, in particular, turned out to be a
key property for the modulation of protonation reactions occurring in vacuo
at the metals in complexes bearing organophosphorus ligands; however,
when the same reactions take place in a polar organic solvent, their
energetics becomes dependent on the trade-off between ligand... (More) - Tailoring the activity of an organometallic catalyst usually requires a
targeted ligand design. Tuning the ligand bulkiness and tuning the
electronic properties are popular approaches, which are somehow
interdependent because substituents of different sizes within ligands
can determine inter alia the occurrence of different degrees of
inductive effects. Ligand basicity, in particular, turned out to be a
key property for the modulation of protonation reactions occurring in vacuo
at the metals in complexes bearing organophosphorus ligands; however,
when the same reactions take place in a polar organic solvent, their
energetics becomes dependent on the trade-off between ligand basicity
and bulkiness, with the polarity of the solvent playing a key role in
this regard [Bancroft et al., Inorg. Chem., 1986, 25, 3675; Rovaletti et al., J. Phys. Org. Chem., 2018, 31,
e3748]. In the present contribution, we carried out molecular dynamics
and density functional theory calculations on water-soluble Mo-based
catalysts for proton reduction, in order to study the energetics of
protonation reactions in complexes where the incipient proton binds a
catalytically active ligand (i.e., an oxide or a disulphide).
We considered complexes either soaked in water or in a vacuum, and
featuring N-based ancillary ligands of different bulkiness (i.e.
cages constituted either by pyridine or isoquinoline moieties). Our
results show that the energetics of protonation events can be affected
by ancillary ligand bulkiness even when the metal center does not play
the role of the H+ acceptor. In vacuo,
protonation at the O or S atom in the α position relative to the metal
in complexes featuring the bulky isoquinoline-based ligand is more
favored by around 10 kcal mol−1 when compared
to the case of the pyridine-based counterparts, a difference that is
almost zero when the same reactions occur in water. Such an outcome is
rationalized in light of the different electrostatic properties of
complexes bearing ancillary ligands of different sizes. The overall
picture from theory indicates that such effects of ligand bulkiness can
be relevant for the design of green chemistry catalysts that undergo
protonation steps in water solutions. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/3a64fdda-6108-4044-a36a-fca949fd66ec
- author
- Rovaletti, Anna
; Ryde, Ulf
LU
; Moro, Giorgio
; Cosentino, Ugo
and Greco, Claudio
LU
- organization
- publishing date
- 2022-12-14
- type
- Contribution to journal
- publication status
- published
- subject
- in
- Physical chemistry chemical physics : PCCP
- volume
- 24
- issue
- 48
- pages
- 9 pages
- publisher
- Royal Society of Chemistry
- external identifiers
-
- scopus:85143225636
- pmid:36437742
- ISSN
- 1463-9084
- DOI
- 10.1039/d2cp03996f
- language
- English
- LU publication?
- yes
- id
- 3a64fdda-6108-4044-a36a-fca949fd66ec
- date added to LUP
- 2023-01-21 10:59:31
- date last changed
- 2024-06-09 11:31:06
@article{3a64fdda-6108-4044-a36a-fca949fd66ec,
abstract = {{Tailoring the activity of an organometallic catalyst usually requires a <br>
targeted ligand design. Tuning the ligand bulkiness and tuning the <br>
electronic properties are popular approaches, which are somehow <br>
interdependent because substituents of different sizes within ligands <br>
can determine <em>inter alia</em> the occurrence of different degrees of<br>
inductive effects. Ligand basicity, in particular, turned out to be a <br>
key property for the modulation of protonation reactions occurring <em>in vacuo</em><br>
at the metals in complexes bearing organophosphorus ligands; however, <br>
when the same reactions take place in a polar organic solvent, their <br>
energetics becomes dependent on the trade-off between ligand basicity <br>
and bulkiness, with the polarity of the solvent playing a key role in <br>
this regard [Bancroft <em>et al.</em>, <em>Inorg. Chem.</em>, 1986, <strong>25</strong>, 3675; Rovaletti <em>et al.</em>, <em>J. Phys. Org. Chem.</em>, 2018, <strong>31</strong>,<br>
e3748]. In the present contribution, we carried out molecular dynamics <br>
and density functional theory calculations on water-soluble Mo-based <br>
catalysts for proton reduction, in order to study the energetics of <br>
protonation reactions in complexes where the incipient proton binds a <br>
catalytically active ligand (<em>i.e.</em>, an oxide or a disulphide). <br>
We considered complexes either soaked in water or in a vacuum, and <br>
featuring N-based ancillary ligands of different bulkiness (<em>i.e.</em><br>
cages constituted either by pyridine or isoquinoline moieties). Our <br>
results show that the energetics of protonation events can be affected <br>
by ancillary ligand bulkiness even when the metal center does not play <br>
the role of the H<sup>+</sup> acceptor. <em>In vacuo</em>,<br>
protonation at the O or S atom in the α position relative to the metal <br>
in complexes featuring the bulky isoquinoline-based ligand is more <br>
favored by around 10 kcal mol<sup>−1</sup> when compared <br>
to the case of the pyridine-based counterparts, a difference that is <br>
almost zero when the same reactions occur in water. Such an outcome is <br>
rationalized in light of the different electrostatic properties of <br>
complexes bearing ancillary ligands of different sizes. The overall <br>
picture from theory indicates that such effects of ligand bulkiness can <br>
be relevant for the design of green chemistry catalysts that undergo <br>
protonation steps in water solutions.}},
author = {{Rovaletti, Anna and Ryde, Ulf and Moro, Giorgio and Cosentino, Ugo and Greco, Claudio}},
issn = {{1463-9084}},
language = {{eng}},
month = {{12}},
number = {{48}},
pages = {{29471--29479}},
publisher = {{Royal Society of Chemistry}},
series = {{Physical chemistry chemical physics : PCCP}},
title = {{How general is the effect of the bulkiness of organic ligands on the basicity of metal-organic catalysts? H<sub>2</sub>-evolving Mo oxides/sulphides as case studies}},
url = {{http://dx.doi.org/10.1039/d2cp03996f}},
doi = {{10.1039/d2cp03996f}},
volume = {{24}},
year = {{2022}},
}