Synthesis and characterisation of new PCsp3P-supported nickel complexes

• A cyclohexyl based phosphine pincer ligand was studied with respect to cyclometalation.
• The first nickel pincer complexes with this ligand are reported.
• Despite long Ni–X bonds the complexes show a low reactivity.

The coordination behaviour of the aliphatic pincer ligand cis-1,3-bis-((di-tert-butylphosphino)methyl)cyclohexane with NiCl2 and NiBr2 was studied. Reflux in toluene afforded cyclometalated, tridentate PCsp3P pincer complexes, that were characterised by elemental analysis and NMR spectroscopy; the solid state structures were determined by X-ray diffraction showing an unusually long Ni–Br bond in the bromo complex. A preliminary account of their reactivity is reported and they were found to be unreactive towards base and hydride sources and to be poor catalysts in Kumada coupling reactions.

Two new PCsp3P nickel pincer complexes with a cyclohexyl skeleton are reported and found to have a comparatively low reactivity towards electrophiles, nucleophiles, hydride sources and base.Figure optionsDownload as PowerPoint slide