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A Comprehensive Analysis of the Metal-Nitrile Bonding in an Organo-Diiron System. Molecules 2021; 26:molecules26237088. [PMID: 34885670 PMCID: PMC8659010 DOI: 10.3390/molecules26237088] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Revised: 11/18/2021] [Accepted: 11/19/2021] [Indexed: 11/17/2022] Open
Abstract
Nitriles (N≡CR) are ubiquitous in coordination chemistry, yet literature studies on metal-nitrile bonding based on a multi-technique approach are rare. We selected an easily-available di-organoiron framework, containing both π-acceptor (CO, aminocarbyne) and donor (Cp = η5-C5H5) ligands, as a suitable system to provide a comprehensive description of the iron-nitrile bond. Thus, the new nitrile (2-12)CF3SO3 and the related imine/amine complexes (8-9)CF3SO3 were synthesized in 58-83% yields from the respective tris-carbonyl precursors (1a-d)CF3SO3, using the TMNO strategy (TMNO = trimethylamine-N-oxide). The products were fully characterized by elemental analysis, IR (solution and solid state) and multinuclear NMR spectroscopy. In addition, the structures of (2)CF3SO3, (3)CF3SO3, (5)CF3SO3 and (11)CF3SO3 were ascertained by single crystal X-ray diffraction. Salient spectroscopic data of the nitrile complexes are coherent with the scale of electron-donor power of the R substituents; otherwise, this scale does not match the degree of Fe → N π-back-donation and the Fe-N bond energies, which were elucidated in (2-7)CF3SO3 by DFT calculations.
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Grigoropoulos A, Whitehead GFS, Perret N, Katsoulidis AP, Chadwick FM, Davies RP, Haynes A, Brammer L, Weller AS, Xiao J, Rosseinsky MJ. Encapsulation of an organometallic cationic catalyst by direct exchange into an anionic MOF. Chem Sci 2016; 7:2037-2050. [PMID: 29899929 PMCID: PMC5968521 DOI: 10.1039/c5sc03494a] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 12/01/2015] [Indexed: 11/21/2022] Open
Abstract
Metal-Organic Frameworks (MOFs) are porous crystalline materials that have emerged as promising hosts for the heterogenization of homogeneous organometallic catalysts, forming hybrid materials which combine the benefits of both classes of catalysts. Herein, we report the encapsulation of the organometallic cationic Lewis acidic catalyst [CpFe(CO)2(L)]+ ([Fp-L]+, Cp = η5-C5H5, L = weakly bound solvent) inside the pores of the anionic [Et4N]3[In3(BTC)4] MOF (H3BTC = benzenetricarboxylic acid) via a direct one-step cation exchange process. To conclusively validate this methodology, initially [Cp2Co]+ was used as an inert spatial probe to (i) test the stability of the selected host; (ii) monitor the stoichiometry of the cation exchange process and (iii) assess pore dimensions, spatial location of the cationic species and guest-accessible space by single crystal X-ray crystallography. Subsequently, the quasi-isosteric [Fp-L]+ was encapsulated inside the pores via partial cation exchange to form [(Fp-L)0.6(Et4N)2.4][In3(BTC)4]. The latter was rigorously characterized and benchmarked as a heterogeneous catalyst in a simple Diels-Alder reaction, thus verifying the integrity and reactivity of the encapsulated molecular catalyst. These results provide a platform for the development of heterogeneous catalysts with chemically and spatially well-defined catalytic sites by direct exchange of cationic catalysts into anionic MOFs.
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Affiliation(s)
| | | | - Noémie Perret
- Department of Chemistry , University of Liverpool , Liverpool L69 7ZD , UK .
| | | | - F Mark Chadwick
- Department of Chemistry , Chemistry Research Laboratories , University of Oxford , Mansfield Road , Oxford OX1 3TA , UK .
| | - Robert P Davies
- Department of Chemistry , Imperial College London , South Kensington , London SW7 2AZ , UK
| | - Anthony Haynes
- Department of Chemistry , University of Sheffield , Brook Hill , Sheffield S3 7HF , UK
| | - Lee Brammer
- Department of Chemistry , University of Sheffield , Brook Hill , Sheffield S3 7HF , UK
| | - Andrew S Weller
- Department of Chemistry , Chemistry Research Laboratories , University of Oxford , Mansfield Road , Oxford OX1 3TA , UK .
| | - Jianliang Xiao
- Department of Chemistry , University of Liverpool , Liverpool L69 7ZD , UK .
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