Linearly Bridging N2 versus CO: Chemical Bonding and Spin‐Controlled Reactivity. Issue 11 (13th February 2023)

• Record Type: Journal Article
• Authors: Fritz, Maximilian; Demeshko, Serhiy; Würtele, Christian; Finger, Markus; Schneider, Sven
• Is Part Of: European journal of inorganic chemistry. Volume 26:Issue 11(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2023-02-13
• Subjects: carbon monoxide -- chemical bonding -- electronic structure -- nitrogen -- reaction mechanisms; Chemistry, Inorganic -- Periodicals; Organometallic chemistry -- Periodicals; Bioinorganic chemistry -- Periodicals; Solid state chemistry -- Periodicals; 546
• DOI: 10.1002/ejic.202300011
• Languages: English
• ISSNs: 1434-1948

Abstract

Abstract: The synthesis of the linearly N2 bridged, dichromium complex [( μ ‐N2 ){Cr(PNP)}2 ] (PNP=N(CHCHP t Bu2 )2 ) is reported. Experimental and computational data favor a three‐spin electronic structure model with high‐spin Cr II ions that are antiferromagnetically coupled to an N2 2− bridge due to spin‐polarized backbonding. Reaction with CO gave isocarbonyl complex [(PNP)(CO)2 Cr( μ ‐CO)Cr(PNP)] and [(PNP)(CO)2 Cr( μ ‐N2 )Cr(PNP)] could be trapped as intermediate. The latter is best described by a (ls‐Cr I )(N2 − )(hs‐Cr II ) ground state model, while more covalent bonding with the CO bridge is reflected by a (ls‐Cr 0 )(CO 0 )(hs‐Cr II ) electronic structure description. The selectivity of the carbonylation reaction is attributed to a spin transition after binding of the first CO ligand to [( μ ‐N2 ){Cr(PNP)}2 ]. Abstract : Chemical bonding of linearly bridging N2 vs. CO ligands in dichromium complexes with otherwise identical environments is compared. The bridging N2 ligand induces spin‐polarized metal‐to‐N2 backbonding with both metal ions. In contrast, the isocarbonyl ligand exhibits largely covalent π‐interactions that are localized at the C ‐terminus, resulting in a smaller degree of charge transfer.