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Drummond Turnbull R, Bell NL. f-Block hydride complexes - synthesis, structure and reactivity. Dalton Trans 2024. [PMID: 38953848 DOI: 10.1039/d4dt00776j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/04/2024]
Abstract
Complexes formed between the heaviest and lightest elements in the periodic table yield the f-block hydrides, a unique class of compounds with wide-ranging utility and interest, from catalysis to light-responsive materials and nuclear waste storage. Recent developments in syntheses and analytics, such as exploiting low-oxidation state metal ions and improvements in X-ray diffraction tools, have transformed our ability to understand, access and manipulate these important species. This perspective brings together insights from binary metal hydrides, with molecular solution phase studies on heteroleptic complexes and gas phase investigations. It aims to provide an overview of how the f-element influences hydride formation, structure and reactivity including the sometimes-surprising power of co-ligands to tune their behaviour towards a variety of applications.
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Affiliation(s)
| | - Nicola L Bell
- School of Chemistry, University of Glasgow, Glasgow, UK, G12 8QQ.
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Zgrabik J, Bhowmick R, Eckstrom FD, Harrison AR, Fetrow TV, Blake AV, Vlaisavljevich B, Daly SR. The Influence of Phosphorus Substituents on the Structures and Solution Speciation of Trivalent Uranium and Lanthanide Phosphinodiboranates. Inorg Chem 2024; 63:9451-9463. [PMID: 38011639 PMCID: PMC11134491 DOI: 10.1021/acs.inorgchem.3c02773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 11/02/2023] [Accepted: 11/03/2023] [Indexed: 11/29/2023]
Abstract
Here, we report the mechanochemical synthesis and characterization of homoleptic uranium and lanthanide phosphinodiboranates with isopropyl and ethyl substituents attached to phosphorus. M(H3BPiPr2BH3)3 complexes with M = U, Nd, Sm, Tb, and Er were prepared by ball milling UI3(THF)4, SmBr3, or MI3 with three equivalents of K(H3BPiPr2BH3). M(H3BPEt2BH3)3 with M = U and Nd were prepared similarly using K(H3BPEt2BH3), and the complexes were purified by extraction and crystallization from Et2O or CH2Cl2. Single-crystal XRD studies revealed that all five M(H3BPiPr2BH3)3 crystallize as dimers, despite the significant differences in metal radii across the series. In contrast, Nd(H3BPEt2BH3)3 with smaller ethyl substituents crystallized as a coordination polymer. Crystals of U(H3BPEt2BH3)3 were not suitable for structural analysis, but crystals of U(H3BPMe2BH3)3 isolated in low yield by solution methods were isostructural with Nd(H3BPEt2BH3)3. 1H and 11B NMR studies in C6D6 revealed that all of the complexes form mixtures of monomer and oligomers when dissolved, and the extent of oligomerization was highly dependent on metal radius and phosphorus substituent size. A comprehensive analysis of all structurally characterized uranium and lanthanide phosphinodiboranate complexes reported to date, including those with larger Ph and tBu substituents, revealed that the degree of oligomerization in solution can be correlated to differences in B-P-B angles obtained from single-crystal XRD studies. Density functional theory calculations, which included structural optimizations in combination with conformational searches using tight binding methods, replicated the general experimental trends and revealed free energy differences that account for the different solution and solid-state structures. Collectively, these results reveal how steric changes to phosphorus substituents significantly removed from metal coordination sites can have a significant influence on solution speciation, deoligomerization energies, and the solid-state structure of homoleptic phosphinodiboranate complexes containing trivalent f-metals.
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Affiliation(s)
- Joshua
C. Zgrabik
- Department
of Chemistry, The University of Iowa, E331 Chemistry Building, Iowa City, Iowa 52242, United States
| | - Rina Bhowmick
- Department
of Chemistry, The University of South Dakota, 414 E Clark St., Vermillion, South Dakota 57069, United States
| | - Francesca D. Eckstrom
- Department
of Chemistry, The University of Iowa, E331 Chemistry Building, Iowa City, Iowa 52242, United States
| | - A. Rayford Harrison
- Department
of Chemistry, The University of Iowa, E331 Chemistry Building, Iowa City, Iowa 52242, United States
| | - Taylor V. Fetrow
- Department
of Chemistry, The University of Iowa, E331 Chemistry Building, Iowa City, Iowa 52242, United States
| | - Anastasia V. Blake
- Department
of Chemistry, The University of Iowa, E331 Chemistry Building, Iowa City, Iowa 52242, United States
| | - Bess Vlaisavljevich
- Department
of Chemistry, The University of South Dakota, 414 E Clark St., Vermillion, South Dakota 57069, United States
| | - Scott R. Daly
- Department
of Chemistry, The University of Iowa, E331 Chemistry Building, Iowa City, Iowa 52242, United States
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Fetrow TV, Zgrabik J, Bhowmick R, Eckstrom FD, Crull G, Vlaisavljevich B, Daly SR. Quantifying the Influence of Covalent Metal-Ligand Bonding on Differing Reactivity of Trivalent Uranium and Lanthanide Complexes. Angew Chem Int Ed Engl 2022; 61:e202211145. [PMID: 36097137 PMCID: PMC9828012 DOI: 10.1002/anie.202211145] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Indexed: 01/12/2023]
Abstract
Qualitative differences in the reactivity of trivalent lanthanide and actinide complexes have long been attributed to differences in covalent metal-ligand bonding, but there are few examples where thermodynamic aspects of this relationship have been quantified, especially with U3+ and in the absence of competing variables. Here we report a series of dimeric phosphinodiboranate complexes with trivalent f-metals that show how shorter-than-expected U-B distances indicative of increased covalency give rise to measurable differences in solution deoligomerization reactivity when compared to isostructural complexes with similarly sized lanthanides. These results, which are in excellent agreement with supporting DFT and QTAIM calculations, afford rare experimental evidence concerning the measured effect of variations in metal-ligand covalency on the reactivity of trivalent uranium and lanthanide complexes.
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Affiliation(s)
- Taylor V. Fetrow
- Department of ChemistryThe University of IowaE331 Chemistry BuildingIowa CityIA 52242USA
| | - Joshua Zgrabik
- Department of ChemistryThe University of IowaE331 Chemistry BuildingIowa CityIA 52242USA
| | - Rina Bhowmick
- Department of ChemistryThe University of South Dakota414 East Clark StreetVermillionSouth Dakota57069USA
| | - Francesca D. Eckstrom
- Department of ChemistryThe University of IowaE331 Chemistry BuildingIowa CityIA 52242USA
| | - George Crull
- Department of ChemistryThe University of IowaE331 Chemistry BuildingIowa CityIA 52242USA
| | - Bess Vlaisavljevich
- Department of ChemistryThe University of South Dakota414 East Clark StreetVermillionSouth Dakota57069USA
| | - Scott R. Daly
- Department of ChemistryThe University of IowaE331 Chemistry BuildingIowa CityIA 52242USA
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