P,C-bond cleavage in the ligand sphere of a nickel(ii) complex

Abstract

Reacting nickel(ii)perchlorate with a bidentate P,N-ligand in methanol leads to P,C-bond cleavage and gives a five-coordinate nickel complex wherein the nickel(ii) site is coordinated by a tridentate P,N,P-ligand and a bidentate N,C-ligand. The carbanion of the latter is the result of the P,C-bond cleaving process. The diamagnetic nickel(ii) complex was characterized by means of elemental analysis, NMR spectroscopy, cyclic voltammetry and X-ray structure analysis.

Coordination of Nickel(II) by 3‐(2‐(Diphenylphosphanyl)phenyl)‐1H‐pyrazole

“…Palladium(II) complexes derived from ligands bearing an aminopyrimidine group show catalytic activities, that strongly depend on the amino group attached to the pyrimidine ring: Tertiary amines give rise to a cyclopalladation reaction (P, C coordination) that takes place at the 6‐position of the pyrimidine ring and finally results in highly active Suzuki catalysts, while primary and secondary amines, leading to the expected P, N coordination, do not show this feature 12. Interestingly, the reaction of Ni(ClO 4 ) 2 with the same type of ligand leads to a splitting of the central P–C bond leaving a phenyl carbanion stabilized by coordination to the central nickel(II) cation and formally a Ph 2 P + fragment, that is stabilized by formation of a P–N bond with the amino group attached to the pyrimidine ring 13. From the according pyrazole derivatives being coordinated to palladium dichloride, catalysts for the Heck reaction are accessible.…”

Preorganized Bimetallic Nickel Complexes of Pyrazolate-Bridged Ligands for Cooperative Substrate Transformation

“…Since many pentacoordinate low spin Ni II systems are known and NMR based evidence suggests a diamagnetic compound, this option seems viable. [233][234][235][236][237][238][239] Nonetheless, a situation in which the CH proton is abstracted by a ligand nitrogen was excluded by the fact that no NH correlation was observed in 15 N-HMBC or HSQC ex periments. Furthermore, the NMR experiments imply a complex geometry similar to the compounds which were discussed in the earlier part of this work.…”