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Title: Similar ligand–metal bonding for transition metals and actinides? 5f 1 U(C 7H 7) 2 - versus 3d n metallocenes

Abstract

U(C 7H 7) 2- is an intriguing 5f 1 complex whose metal–ligand bonding was assigned in the literature as being very similar to 3d 7 cobaltocene, based on a crystal-field theoretical interpretation of the experimental magnetic resonance data. The present work provides an in-depth theoretical study of the electronic structure, bonding, and magnetic properties of the 5f 1 U(C 7H 7) 2-vs. 3d metallocenes with V, Co, and Ni, performed with relativistic wavefunction and density functional methods. The ligand to metal donation bonding in U(C 7H 7) 2- is strong and in fact similar to that in vanadocene, in the sense that the highest occupied arene orbitals donate electron density into empty metal orbitals of the same symmetry with respect to the rotational axis (3d π for V, 5f δ for U), but selectively with α spin (↑). For Co and Ni, the dative bonding from the ligands is β spin (↓) selective into partially filled 3d π orbitals. In all systems, this spin delocalization triggers spin polarization in the arene σ bonding framework, causing proton spin densities opposite to those of the carbons. Because of this, the proton spin densities and hyperfine coupling constants A$$1h\atop{iso}$$ are negative for the Co and Ni complex, but positive for vanadocene. The A$$1h\atop{iso}$$ of U(C 7H 7) 2- is negative and similar to that of cobaltocene, but only because of the strong spin–orbit coupling in the actinocene, which causes A$$1h\atop{iso}$$ to be opposite to the sign of the proton spin density. The study contributes to a better understanding of actinide 5f vs. transition metal 3d covalency, and highlights potential pitfalls when interpreting experimental magnetic resonance data in terms of covalent bonding for actinide complexes.

Authors:
ORCiD logo [1]; ORCiD logo [1]; ORCiD logo [1]
  1. Univ. at Buffalo, Buffalo, NY (United States)
Publication Date:
Research Org.:
Univ. of Maryland, College Park, MD (United States); Research Foundation (RF) for the State Univ. of New York (SUNY), Amherst, NY (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
OSTI Identifier:
1459033
Alternate Identifier(s):
OSTI ID: 1505227
Grant/Contract Number:  
SC0001160; SC0001136
Resource Type:
Journal Article: Published Article
Journal Name:
Chemical Science
Additional Journal Information:
Journal Volume: 9; Journal Issue: 29; Journal ID: ISSN 2041-6520
Publisher:
Royal Society of Chemistry
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

Citation Formats

Sergentu, Dumitru-Claudiu, Gendron, Frédéric, and Autschbach, Jochen. Similar ligand–metal bonding for transition metals and actinides? 5f1 U(C7H 7)2- versus 3dn metallocenes. United States: N. p., 2018. Web. doi:10.1039/c7sc05373h.
Sergentu, Dumitru-Claudiu, Gendron, Frédéric, & Autschbach, Jochen. Similar ligand–metal bonding for transition metals and actinides? 5f1 U(C7H 7)2- versus 3dn metallocenes. United States. doi:10.1039/c7sc05373h.
Sergentu, Dumitru-Claudiu, Gendron, Frédéric, and Autschbach, Jochen. Mon . "Similar ligand–metal bonding for transition metals and actinides? 5f1 U(C7H 7)2- versus 3dn metallocenes". United States. doi:10.1039/c7sc05373h.
@article{osti_1459033,
title = {Similar ligand–metal bonding for transition metals and actinides? 5f1 U(C7H 7)2- versus 3dn metallocenes},
author = {Sergentu, Dumitru-Claudiu and Gendron, Frédéric and Autschbach, Jochen},
abstractNote = {U(C7H7)2- is an intriguing 5f1 complex whose metal–ligand bonding was assigned in the literature as being very similar to 3d7 cobaltocene, based on a crystal-field theoretical interpretation of the experimental magnetic resonance data. The present work provides an in-depth theoretical study of the electronic structure, bonding, and magnetic properties of the 5f1 U(C7H7)2-vs. 3d metallocenes with V, Co, and Ni, performed with relativistic wavefunction and density functional methods. The ligand to metal donation bonding in U(C7H7)2- is strong and in fact similar to that in vanadocene, in the sense that the highest occupied arene orbitals donate electron density into empty metal orbitals of the same symmetry with respect to the rotational axis (3dπ for V, 5fδ for U), but selectively with α spin (↑). For Co and Ni, the dative bonding from the ligands is β spin (↓) selective into partially filled 3dπ orbitals. In all systems, this spin delocalization triggers spin polarization in the arene σ bonding framework, causing proton spin densities opposite to those of the carbons. Because of this, the proton spin densities and hyperfine coupling constants A$1h\atop{iso}$ are negative for the Co and Ni complex, but positive for vanadocene. The A$1h\atop{iso}$ of U(C7H7)2- is negative and similar to that of cobaltocene, but only because of the strong spin–orbit coupling in the actinocene, which causes A$1h\atop{iso}$ to be opposite to the sign of the proton spin density. The study contributes to a better understanding of actinide 5f vs. transition metal 3d covalency, and highlights potential pitfalls when interpreting experimental magnetic resonance data in terms of covalent bonding for actinide complexes.},
doi = {10.1039/c7sc05373h},
journal = {Chemical Science},
issn = {2041-6520},
number = 29,
volume = 9,
place = {United States},
year = {2018},
month = {6}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1039/c7sc05373h

Citation Metrics:
Cited by: 2 works
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Works referenced in this record:

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