Universität zu Köln

Vogt, Nicolas, Sandleben, Aaron, Kletsch, Lukas, Schaefer, Sascha ORCID: 0000-0001-6035-1281, Chin, Mason T., Vicic, David A., Hoerner, Gerald ORCID: 0000-0002-3883-2879 and Klein, Axel ORCID: 0000-0003-0093-9619 (2021). Role of the X Coligands in Cyclometalated [Ni(Phbpy)X] Complexes (HPhbpy=6-Phenyl-2,2 '-bipyridine). Organometallics, 40 (11). S. 1776 - 1786. WASHINGTON: AMER CHEMICAL SOC. ISSN 1520-6041

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Abstract

The coligand X was varied in the organonickel complexes [Ni(Phbpy)X] (X = F, Cl, Br, I, C6F5) carrying the anionic tridentate C boolean AND N boolean AND N ligand 6-(phen-2-ide)-2,2'-bipyridine (Phbpy(-)) to study its effect on electronic structures of these complexes and their activity in Negishi-like C-C cross-coupling catalysis. The complexes were synthesized from the precursor [Ni(COD)(2)] (COD = 1,5-cyclooctadiene) by chelate-assisted oxidative addition into the phenyl C-X bond of the protoligand 6-(2-halidophenyl)-2,2'-bipyridine) and were obtained as red powders. Protoligands X-Phbpy carrying the halide surrogates X = OMe, OTf (triflate) failed in this reaction. Single-crystal XRD allowed us to add the structures of [Ni(Phbpy)Cl] and [Ni(Phbpy)I] to the previously reported Br derivative. Cyclic voltammetry showed reversible reductions for X = C6F5, F, Cl, while for Br and I the reversibility is reduced through rapid splitting of X - after reduction (EC mechanism). UV-vis spectroelectrochemistry confirmed the decreasing degree of reversibility along the series C6F5 > F > CI >> Br > I, which parallels the leaving group character of the X coligands. This method also revealed mainly bpy centered reduction and essentially Ni(II)/Ni(III) oxidations, as corroborated by DFT calculations. The rather X-invariant long-wavelength UV-vis absorptions and excited states were analyzed in detail using TD-DFT and were consistent with predominant metal to ligand charge transfer (MLCT) character. Initial catalytic tests under Negishi-like conditions showed the complexes to be active as catalysts in C-C cross-coupling reactions but did not display marked differences along the series from Ni-F to Ni-I.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Vogt, Nicolas UNSPECIFIED UNSPECIFIED UNSPECIFIED Sandleben, Aaron UNSPECIFIED UNSPECIFIED UNSPECIFIED Kletsch, Lukas UNSPECIFIED UNSPECIFIED UNSPECIFIED Schaefer, Sascha UNSPECIFIED orcid.org/0000-0001-6035-1281 UNSPECIFIED Chin, Mason T. UNSPECIFIED UNSPECIFIED UNSPECIFIED Vicic, David A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Hoerner, Gerald UNSPECIFIED orcid.org/0000-0002-3883-2879 UNSPECIFIED Klein, Axel UNSPECIFIED orcid.org/0000-0003-0093-9619 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-580475
DOI:	10.1021/acs.organomet.1c00237
Journal or Publication Title:	Organometallics
Volume:	40
Number:	11
Page Range:	S. 1776 - 1786
Date:	2021
Publisher:	AMER CHEMICAL SOC
Place of Publication:	WASHINGTON
ISSN:	1520-6041
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language ORGANONICKEL COMPLEXES; NICKEL(II) COMPLEXES; ELECTRONIC-STRUCTURE; PLANAR NICKEL(II); ALPHA-DIIMINES; LIGAND; ALKYL; REACTIVITY; 6-PHENYL-2,2'-BIPYRIDINE; SPECTROSCOPY Multiple languages Chemistry, Inorganic & Nuclear; Chemistry, Organic Multiple languages
URI:	http://kups.ub.uni-koeln.de/id/eprint/58047