Conversion of imine ligands in allyl–nickel(II) complexes

2D-NMR and EPR study of the activation of π-allyl group within the coordination sphere of the imine–amide complex of nickel(II) by the coordination of PMe

“…The consideration of the signals in the 13 S and 1 H NMR spectra together with the HSQC, HMBC, COSY, NOESY and 1 He 15 N HMBC spectra (detailed spectra in Supplementary material) and comparison of them with the reported data [8] let us see no rearrangement in the imineeamide ligand. In this respect the signal at 4.37 ppm in the 1 H NMR spectrum is most demonstrative because it correlates with the 13 S signal at 62.94 ppm in the HSQC as well as with the signals at 49.25 and 155.77 ppm in the HMBC that unambiguously points to the imineeamide character of the nitrogen-containing ligand and the presence of a NieN s-bond [8,9]. Thus, the combination of the NMR and elemental analysis data allows one to assert that the reaction of imineeamide complex 1 with trimethylphosphine gives birth to complex 3 (Scheme 3).…”

“…It was reported [8,9] that the reaction of phenanthroline-1,10 with Ni(allyl) 2 gave nickel(II) imineeamide allyl complex 1 (Scheme 1).…”

“…Complex 1 has interesting chemical properties. Despite the presence of allyl group, complex 1 does not react with olefins and acetylenes [9]. At the same time complex 1, when sealed in an evacuated ampoule as a solution in THF or C 6 H 6 , spontaneously and gradually disproportionates giving the nickel(I) allyl complex and hydrogen [10] (Scheme 2).…”

Intramolecular rearrangement of the imine–amide ligand within the nickel coordination sphere affected by carbon monoxide

“…According to an Xray structural analysis and multinuclear 2D NMR spectroscopy [20] 1 has a planar structure, contains a p-allyl group, an active fragment, and, besides, it is electron-deficient with its 16-electron pattern. On the whole complex 1 meets all the conventional requirements for a catalyst [21].…”

“…The possibility of a profound transformation of diimine ligands within the coordination sphere of a nickel p-allyl complex was demonstrated in [20]. The process involves formation of a nickelenitrogen s-bond and an imineeamide complex.…”