Divalent Titanium via Reductive N−C Coupling of a TiIV Nitrido with π-Acids

Bhunia M, Sandoval-Pauker C, Fehn D, Grant LN, Senthil S, Gau MR, Ozarowski A, Krzystek J, Telser J, Pinter B, Meyer K, Mindiola DJ (2024)

Publication Type: Journal article

Publication year: 2024

Journal

Angewandte Chemie International Edition Wiley

DOI: 10.1002/anie.202404601

Abstract

The nitrido-ate complex [(PN)2Ti(N){μ2-K(OEt2)}]2 (1) (PN⁻=(N-(2-PⁱPr2-4-methylphenyl)-2,4,6-Me3C6H2) reductively couples CO and isocyanides in the presence of DME or cryptand (Kryptofix222), to form rare, five-coordinate Ti^II complexes having a linear cumulene motif, [K(L)][(PN)2Ti(NCE)] (E=O, L=Kryptofix222, (2); E=NAd, L=3 DME, (3); E=N^tBu, L=3 DME, (4); E=NAd, L=Kryptofix222, (5)). Oxidation of 2–5 with [Fc][OTf] afforded an isostructural Ti^III center containing a neutral cumulene, [(PN)2Ti(NCE)] (E=O, (6); E=NAd (7), N^tBu (8)) and characterization by CW X-band EPR spectroscopy, revealed unpaired electron to be metal centric. Moreover, 1e⁻ reduction of 6 and 7 in the presence of Kryptofix222cleanly reformed corresponding discrete Ti^II complexes 2 and 5, which were further characterized by solution magnetization measurements and high-frequency and -field EPR (HFEPR) spectroscopy. Furthermore, oxidation of 7 with [Fc*][B(C6F5)4] resulted in a ligand disproportionated Ti^IV complex having transoid carbodiimides, [(PN)2Ti(NCNAd)2] (9). Comparison of spectroscopic, structural, and computational data for the divalent, trivalent, and tetravalent systems, including their ¹⁵N enriched isotopomers demonstrate these cumulenes to decrease in order of backbonding as Ti^II→Ti^III→Ti^IV and increasing order of π-donation as Ti^II→Ti^III→Ti^IV, thus displaying more covalency in Ti^III species. Lastly, we show a synthetic cycle whereby complex 1 can deliver an N-atom to CO and CNAd.

Authors with CRIS profile

Dominik Fehn Lehrstuhl für Anorganische und Allgemeine Chemie Karsten Meyer Lehrstuhl für Anorganische und Allgemeine Chemie

Involved external institutions

University of Pennsylvania

United States (USA) (US) The University of Texas at El Paso

United States (USA) (US) Florida State University (FSU)

United States (USA) (US) Roosevelt University

United States (USA) (US)

How to cite

APA:

Bhunia, M., Sandoval-Pauker, C., Fehn, D., Grant, L.N., Senthil, S., Gau, M.R.,... Mindiola, D.J. (2024). Divalent Titanium via Reductive N−C Coupling of a TiIV Nitrido with π-Acids. Angewandte Chemie International Edition. https://doi.org/10.1002/anie.202404601

MLA:

Bhunia, Mrinal, et al. "Divalent Titanium via Reductive N−C Coupling of a TiIV Nitrido with π-Acids." Angewandte Chemie International Edition (2024).

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