51
|
Abstract
It is well-recognized that N-heterocyclic carbene (NHC) ligands have provided a new dimension to the design of homogeneous catalysts. Part of the success of this type of ligands resides in the limitless access to a variety of topologies with tuned electronic properties, but also in the ability of a family of NHCs that are able to adapt their properties to the specific requirements of individual catalytic transformations. The term "smart" is used here to refer to switchable, multifunctional, adaptable, or tunable ligands and, in general, to all those ligands that are able to modify their steric or electronic properties to fulfill the requirements of a defined catalytic reaction. The purpose of this review is to comprehensively describe all types of smart NHC ligands by focusing attention on the catalytically relevant ligand-based reactivity.
Collapse
Affiliation(s)
- Eduardo Peris
- Institute of Advanced Materials , Universitat Jaume I , Avenida Vicente Sos Baynat s/n , Castellón E-12071 , Spain
| |
Collapse
|
52
|
Walz F, Moos E, Garnier D, Köppe R, Anson CE, Breher F. A Redox-Switchable Germylene and its Ligating Properties in Selected Transition Metal Complexes. Chemistry 2017; 23:1173-1186. [PMID: 27883244 DOI: 10.1002/chem.201605073] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Indexed: 12/22/2022]
Abstract
The synthesis, structure, and full characterization of a redox-switchable germylene based on a [3]ferrocenophane ligand arrangement, [Fc(NMes)2 Ge] (4), is presented. The mesityl (Mes)-substituted title compound is readily available from Fc(NHMes)2 (2) and Ge{N(SiMe3 )2 }2 , or from the dilithiated, highly air- and moisture-sensitive compound Fc(NLiMes)2 ⋅3 Et2 O (3) and GeCl2 . Cyclic voltammetry studies are provided for 4, confirming the above-mentioned view of a redox-switchable germylene metalloligand. Although several 1:1 RhI and IrI complexes of 4 (5-7) are cleanly formed in solution, all attempts to isolate them in pure form failed due to stability problems. However, crystalline solids of [Mo(κ1 Ge-4)2 (CO)4 ] (8) and [W(κ1 Ge-4)2 (CO)4 ] (9) were isolated and fully characterized by common spectroscopic techniques (8 by X-ray diffraction). DFT calculations were performed on a series of model compounds to elucidate a conceivable interplay between the metal atoms in neutral and cationic bimetallic complexes of the type [Rh(κ1 E-qE)(CO)2 Cl]0/+ (qE=[Fc(NPh)2 E] with E=C, Si, Ge). The bonding characteristics of the coordinated Fc-based metalloligands (qE/qE+ ) are strongly affected upon in silico oxidation of the calculated complexes. The calculated Tolman electronic parameter (TEP) significantly increases by approximately 20 cm-1 (E=C) to 25 cm-1 (E=Si, Ge) upon oxidation. The change in the ligand-donating abilities upon oxidation can mainly be attributed to Coulombic effects, whereas an orbital-based interaction appears to have only a minor influence.
Collapse
Affiliation(s)
- Florian Walz
- Institute of Inorganic Chemistry, Karlsruhe Institute of Technology (KIT), Engesserstr. 15, 76131, Karlsruhe, Germany
| | - Eric Moos
- Institute of Inorganic Chemistry, Karlsruhe Institute of Technology (KIT), Engesserstr. 15, 76131, Karlsruhe, Germany
| | - Delphine Garnier
- Institute of Inorganic Chemistry, Karlsruhe Institute of Technology (KIT), Engesserstr. 15, 76131, Karlsruhe, Germany.,Institute of Organic Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569, Stuttgart, Germany
| | - Ralf Köppe
- Institute of Inorganic Chemistry, Karlsruhe Institute of Technology (KIT), Engesserstr. 15, 76131, Karlsruhe, Germany
| | - Christopher E Anson
- Institute of Inorganic Chemistry, Karlsruhe Institute of Technology (KIT), Engesserstr. 15, 76131, Karlsruhe, Germany
| | - Frank Breher
- Institute of Inorganic Chemistry, Karlsruhe Institute of Technology (KIT), Engesserstr. 15, 76131, Karlsruhe, Germany
| |
Collapse
|
53
|
Oetzel J, Weyer N, Bruhn C, Leibold M, Gerke B, Pöttgen R, Maier M, Winter RF, Holthausen MC, Siemeling U. Redox-Active N-Heterocyclic Germylenes and Stannylenes with a Ferrocene-1,1'-diyl Backbone. Chemistry 2017; 23:1187-1199. [PMID: 27859833 DOI: 10.1002/chem.201605074] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 11/16/2016] [Indexed: 12/20/2022]
Abstract
We describe ferrocene-based N-heterocyclic germylenes and stannylenes of the type [Fe{(η5 -C5 H4 )NR}2 E:] (1 RE; E=Ge, Sn; R=neopentyl (Np), mesityl (Mes), trimethylsilyl (TMS)), which constitute the first examples of redox-functionalised N-heterocyclic tetrylenes (NHTs). These compounds are thermally stable and were structurally characterised by means of X-ray diffraction studies, except for the neopentyl-substituted stannylene 1 NpSn, the decomposition of which afforded the aminoiminoferrocene [fc(NHCH2 tBu)(N=CHtBu)] (2) and the spiro tin(IV) compound (1 Np)2 Sn (3). DFT calculations show that the HOMO of the NHTs of our study is localised on the ferrocenylene backbone. A one-electron oxidation process affords ions of the type 1 RE+. . In contrast to the NHC system 1 RC, the localised ferrocenium-type nature of the oxidised form does not compromise the fundamental tetrylene character of 1 RE+. .
Collapse
Affiliation(s)
- Jan Oetzel
- Institute of Chemistry, University of Kassel, Heinrich-Plett-Strasse 40, 34132, Kassel, Germany
| | - Nadine Weyer
- Institute of Chemistry, University of Kassel, Heinrich-Plett-Strasse 40, 34132, Kassel, Germany
| | - Clemens Bruhn
- Institute of Chemistry, University of Kassel, Heinrich-Plett-Strasse 40, 34132, Kassel, Germany
| | - Michael Leibold
- Institute of Chemistry, University of Kassel, Heinrich-Plett-Strasse 40, 34132, Kassel, Germany
| | - Birgit Gerke
- Institut für Anorganische und Analytische Chemie, Universität Münster, Corrensstrasse 30, 48149, Münster, Germany
| | - Rainer Pöttgen
- Institut für Anorganische und Analytische Chemie, Universität Münster, Corrensstrasse 30, 48149, Münster, Germany
| | - Markus Maier
- Fachbereich Chemie, Universität Konstanz, Universitätsstrasse 10, 78453, Konstanz, Germany
| | - Rainer F Winter
- Fachbereich Chemie, Universität Konstanz, Universitätsstrasse 10, 78453, Konstanz, Germany
| | - Max C Holthausen
- Institut für Anorganisch und Analytische Chemie, Johann Wolfgang Goethe-Universität Frankfurt, Max-von-Laue-Strasse 7, 60438, Frankfurt am Main, Germany
| | - Ulrich Siemeling
- Institute of Chemistry, University of Kassel, Heinrich-Plett-Strasse 40, 34132, Kassel, Germany
| |
Collapse
|
54
|
Helmdach K, Dörk S, Villinger A, Seidel WW. Sterically encumbered metalla-diphosphines: unlocking alkyne rotation by PtII coordination. Dalton Trans 2017. [DOI: 10.1039/c7dt01803g] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Chelate coordination of a redoxactive metalla-diphosphine at PtCl2 changes the electronic structure at the alkyne complex moiety significantly, which is reflected in the onset of rotational isomerism.
Collapse
Affiliation(s)
- Kai Helmdach
- Institut für Chemie
- Universität Rostock
- 18059 Rostock
- Germany
| | - Stephan Dörk
- Institut für Chemie
- Universität Rostock
- 18059 Rostock
- Germany
| | | | | |
Collapse
|
55
|
Feyrer A, Breher F. Palladium complexes of ferrocene-based phosphine ligands as redox-switchable catalysts in Buchwald–Hartwig cross-coupling reactions. Inorg Chem Front 2017. [DOI: 10.1039/c7qi00125h] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Redox-switchable catalysis: Palladium(ii) complexes of two differently substituted [1]phosphaferrocenophanes FcPR (R = Mes, biaryl) and of diphenylferrocenyl phosphine Ph2PFc were applied in redox-switchable Buchwald–Hartwig cross-coupling reactions.
Collapse
Affiliation(s)
- Alexander Feyrer
- Institute of Inorganic Chemistry
- Karlsruhe Institute of Technology (KIT)
- 76131 Karlsruhe
- Germany
| | - Frank Breher
- Institute of Inorganic Chemistry
- Karlsruhe Institute of Technology (KIT)
- 76131 Karlsruhe
- Germany
| |
Collapse
|
56
|
Ibáñez S, Poyatos M, Peris E. A D3h-symmetry hexaazatriphenylene-tris-N-heterocyclic carbene ligand and its coordination to iridium and gold: preliminary catalytic studies. Chem Commun (Camb) 2017; 53:3733-3736. [DOI: 10.1039/c7cc00525c] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A planar star-shaped tris-NHC ligand with a hexaazatriphenylene core was coordinated to gold and iridium. The tris–Au(i) complex shows enhanced catalytic activities due to the electron-deficient character of the HAT core.
Collapse
Affiliation(s)
- S. Ibáñez
- Institute of Advanced Materials (INAM)
- Universitat Jaume I
- Castellón 12071
- Spain
| | - M. Poyatos
- Institute of Advanced Materials (INAM)
- Universitat Jaume I
- Castellón 12071
- Spain
| | - E. Peris
- Institute of Advanced Materials (INAM)
- Universitat Jaume I
- Castellón 12071
- Spain
| |
Collapse
|
57
|
Ibáñez S, Poyatos M, Peris E. A Ferrocenyl-Benzo-Fused Imidazolylidene Complex of Ruthenium as Redox-Switchable Catalyst for the Transfer Hydrogenation of Ketones and Imines. ChemCatChem 2016. [DOI: 10.1002/cctc.201601025] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Susana Ibáñez
- Institute of Advanced Materials (INAM); Universitat Jaume I, Avda. Sos Baynat.; E-12071- Castellón Spain
| | - Macarena Poyatos
- Institute of Advanced Materials (INAM); Universitat Jaume I, Avda. Sos Baynat.; E-12071- Castellón Spain
| | - Eduardo Peris
- Institute of Advanced Materials (INAM); Universitat Jaume I, Avda. Sos Baynat.; E-12071- Castellón Spain
| |
Collapse
|