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Experimental and computational studies of high-valent nickel and palladium complexes

Citation

Camasso, NM and Canty, AJ and Ariafard, A and Sanford, MS, Experimental and computational studies of high-valent nickel and palladium complexes, Organometallics, 36, (22) pp. 4382-4393. ISSN 0276-7333 (2017) [Refereed Article]


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DOI: doi:10.1021/acs.organomet.7b00613

Abstract

This article describes a detailed comparison of the organometallic chemistry of high-valent nickel and palladium model complexes supported by tris(pyrazolyl)borate and cycloneophyl ligands. The accessibility of the MIII and MIV oxidation states with each metal is investigated through electrochemical and chemical oxidation of the MII precursors. These studies show that the NiII precursor readily undergoes both one- and two-electron oxidations to generate stable NiIII and NiIV products. In contrast, under the conditions examined, the PdII analogue undergoes exclusively two-electron-oxidation reactions to form PdIV. Reactivity studies of isolated NiIV and PdIV complexes show that both participate in C(sp3)–heteroatom coupling reactions and that the reactions at NiIV are approximately 2 orders of magnitude faster than those at PdIV. Experimental and computational mechanistic studies implicate outer-sphere SN2-type pathways for these processes. With most nucleophiles (e.g., phenoxide, acetate, thiophenoxide), the C(sp3)–heteroatom coupling reaction yields a TpMII(σ-aryl) product. However, with azide as the nucleophile, the NiII product of initial C(sp3)–N3 coupling undergoes a subsequent C(sp2)–N insertion reaction. Computations implicate an anionic NiIII–nitrene intermediate in this process and show that the Pd analogue of this species is a much higher energy species. Overall, the combined experimental and computational studies demonstrate remarkable similarities in the chemistry of NiIV and PdIV but an enhanced role for NiIII in enabling reactivity which is distinct from that of palladium.

Item Details

Item Type:Refereed Article
Keywords:nickel, palladium, density functional theory, organometallic
Research Division:Chemical Sciences
Research Group:Other Chemical Sciences
Research Field:Organometallic Chemistry
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Chemical Sciences
Author:Canty, AJ (Professor Allan Canty)
Author:Ariafard, A (Associate Professor Alireza Ariafard)
ID Code:122766
Year Published:2017
Deposited By:Chemistry
Deposited On:2017-11-28
Last Modified:2017-11-28
Downloads:0

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