Bonding in Barium Boryloxides, Siloxides, Phenoxides and Silazides: A Comparison with the Lighter Alkaline Earths

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Title: Bonding in Barium Boryloxides, Siloxides, Phenoxides and Silazides: A Comparison with the Lighter Alkaline Earths
Authors: Le Coz, Erwann, Hammoud, Joanna, Roisnel, Thierry, Cordier, Marie, Dorcet, Vincent, Kahlal, Samia, Carpentier, Jean-Francois, Saillard, Jean-Yves, Sarazin, Yann
Contributors: Jonchère, Laurent
Source: Chemistry – A European Journal. 27:11966-11982
Publisher Information: Wiley, 2021.
Publication Year: 2021
Subject Terms: Barium, [CHIM] Chemical Sciences, alkaline-earth metals, O-based ligands, Bonding analysis, DFT, 01 natural sciences, 0104 chemical sciences
Description: Barium complexes ligated by bulky boryloxides [OBR2]− (where R=CH(SiMe3)2, 2,4,6‐iPr3‐C6H2 or 2,4,6‐(CF3)3‐C6H2), siloxide [OSi(SiMe3)3]−, and/or phenoxide [O‐2,6‐Ph2‐C6H3]−, have been prepared. A diversity of coordination patterns is observed in the solid state for both homoleptic and heteroleptic complexes, with coordination numbers ranging between 2 and 4. The identity of the bridging ligand in heteroleptic dimers [Ba(μ2‐X1)(X2)]2 depends largely on the given pair of ligands X1 and X2. Experimentally, the propensity to fill the bridging position increases according to [OB{CH(SiMe3)2}2)]−3)2]−3)3]−2‐C6H3)]−iPr3‐C6H2)2]−. This trend is the overall expression of 3 properties: steric constraints, electronic density and σ‐ and π‐donating capability of the negatively charged atom, and ability to generate Ba ⋅ ⋅ ⋅ F, Ba ⋅ ⋅ ⋅ C(π) or Ba ⋅ ⋅ ⋅ H−C secondary interactions. The comparison of the structural motifs in the complexes [Ae{μ2‐N(SiMe3)2}(OB{CH(SiMe3)2}2)]2 (Ae = Mg, Ca, Sr and Ba) suggest that these observations may be extended to all alkaline earths. DFT calculations highlight the largely prevailing ionic character of ligand‐Ae bonding in all compounds. The ionic character of the Ae‐ligand bond encourages bridging coordination, whereas the number of bridging ligands is controlled by steric factors. DFT computations also indicate that in [Ba(μ2‐X1)(X2)]2 heteroleptic dimers, ligand predilection for bridging vs. terminal positions is dictated by the ability to establish secondary interactions between the metals and the ligands.
Document Type: Article
File Description: application/pdf
Language: English
ISSN: 1521-3765
0947-6539
DOI: 10.1002/chem.202101687
Access URL: https://hal.archives-ouvertes.fr/hal-03282741/document
https://pubmed.ncbi.nlm.nih.gov/34121256
https://europepmc.org/article/MED/34121256
https://chemistry-europe.onlinelibrary.wiley.com/doi/10.1002/chem.202101687
https://www.infona.pl/resource/bwmeta1.element.wiley-chem-v-27-i-46-chem202101687
https://hal.archives-ouvertes.fr/hal-03282741
https://hal.science/hal-03282741v1
https://hal.science/hal-03282741v1/document
https://doi.org/10.1002/chem.202101687
Rights: Wiley Online Library User Agreement
Accession Number: edsair.doi.dedup.....caf2c4c372b742c506cc1dbcbb53e727
Database: OpenAIRE
Description
Abstract:Barium complexes ligated by bulky boryloxides [OBR2]− (where R=CH(SiMe3)2, 2,4,6‐iPr3‐C6H2 or 2,4,6‐(CF3)3‐C6H2), siloxide [OSi(SiMe3)3]−, and/or phenoxide [O‐2,6‐Ph2‐C6H3]−, have been prepared. A diversity of coordination patterns is observed in the solid state for both homoleptic and heteroleptic complexes, with coordination numbers ranging between 2 and 4. The identity of the bridging ligand in heteroleptic dimers [Ba(μ2‐X1)(X2)]2 depends largely on the given pair of ligands X1 and X2. Experimentally, the propensity to fill the bridging position increases according to [OB{CH(SiMe3)2}2)]−3)2]−3)3]−2‐C6H3)]−iPr3‐C6H2)2]−. This trend is the overall expression of 3 properties: steric constraints, electronic density and σ‐ and π‐donating capability of the negatively charged atom, and ability to generate Ba ⋅ ⋅ ⋅ F, Ba ⋅ ⋅ ⋅ C(π) or Ba ⋅ ⋅ ⋅ H−C secondary interactions. The comparison of the structural motifs in the complexes [Ae{μ2‐N(SiMe3)2}(OB{CH(SiMe3)2}2)]2 (Ae = Mg, Ca, Sr and Ba) suggest that these observations may be extended to all alkaline earths. DFT calculations highlight the largely prevailing ionic character of ligand‐Ae bonding in all compounds. The ionic character of the Ae‐ligand bond encourages bridging coordination, whereas the number of bridging ligands is controlled by steric factors. DFT computations also indicate that in [Ba(μ2‐X1)(X2)]2 heteroleptic dimers, ligand predilection for bridging vs. terminal positions is dictated by the ability to establish secondary interactions between the metals and the ligands.
ISSN:15213765
09476539
DOI:10.1002/chem.202101687