Square‐Planar 2‐Toluenido(triphenylphosphane)nickel(II) Complexes Containing Bidentate N,O Ligands: An Example of Planar Chirality

Abstract

Nickel(II) complexes comprising electronically delocalised N,O‐chelating ligands are active catalysts in the copolymerisation of carbon monoxide and ethene. Elucidating the mechanism of catalysis presupposes the basic understanding of the intramolecular flexibility of such transition metal complexes. Several nickel(II) complexes with or without planar chirality were synthesised and characterised by NMR spectroscopic techniques and X‐ray diffraction.

Catalyst Deactivation by β‐Hydride Elimination: Olefin and Alkyne Insertion into Arenido–Nickel(II) Bonds

“…Unless otherwise stated chemicals were purchased from commercial sources, used as received and dried and degassed by standard methods. 4,4,5,5,6,6,6-Heptafluoro-3-oxo-2-[(2Z)-pyrrolidin-2-ylidene]hexanenitrile [12] (4) and the complexes 3a [4] and 3b [35] were prepared according to literature procedures. (14) The magnetic moment µ eff = 3.1 BM was determined in methanolic solution by a standard Evans setup.…”

Square-planar mesitylenido(triphenylphosphane)nickel(II) complexes containing bidendate N,O-ligands: Changes in catalytic efficiency upon small alterations in the ligand backbone

“…Complex K 1 was synthesised as previously described [14]. The synthesis of K 2 and K 3 involves the deprotonation of the protonated N,O-ligand HL 2 or HL 3 and the following reaction of the deprotonated ligand (L 2 ) À or (L 3 ) À , respectively, with (SP-4-3)-[NiBr(mes)(PPh 3 ) 2 ] in a toluene solution.…”

“…The nickel complexes K 1 and K 1 0 comprising a N,O-chelate ligand with a five-membered heterocycle are catalysts for the copolymerisation of ethene and carbon monoxide [12,14]. We reported new nickel complexes in which the five-membered heterocycle of the bidentate N,O-ligand was altered to six-and seven-membered rings, K 2 , K 2 0 , K 3 and K 3 0 .…”

“…The synthesis was carried out as previously described [14]. Single crystals of the complex suitable for X-ray diffraction were obtained upon cooling by slow crystallisation from hot methanol.…”

“…Single crystals of HL 1e3 suitable for X-ray diffraction were obtained by slow evaporation of a saturated diethyl ether solution of each ligand HL 1e3 . The synthesis of (SP-4-3)-[Ni(L 1 )(2-tol)(PPh 3 )] K 1 0 was carried out as described previously [14].…”