Synthesis and structural characterization of Ni(II) complexes with the chiral CpH(PNMent) tripod ligand

Treatment of NiCl2 with the tripod ligand (L-Ment, S-C)-1H led to (L-Ment, S-C)-[Cp(PNMent) NiCl] in which the potentially tridentate ligand coordinated to the metal center in a bidentate way via the cyclopentadienyl system and the phosphorus atom. In the presence of NH4PF6 [(L-Ment, S-C)[Cp(PNMent) NiCl] readily underwent Cl/PPh3 exchange to give (L-Ment, S-C)-[Cp(PNMent) NiPPh3] PF6. Reaction of (L-Ment, S-C)-[Cp(PNMent) NiCl] with 0.5 eq. of dppe afforded [{(L-Ment, S-C)-[Cp(PNMent) Ni]}(2) dppe](PF6)(2). (L-Ment, S-C)-[Cp(PNMent) NiPPh3] PF6 and [{(L-Ment, S-C)-[Cp(PNMent) Ni]}(2) dppe] (PF6)(2) were characterized by NMR and MS spectroscopy, and also by single crystal X-ray diffraction. The cyclopentadienyl ligand of (L-Ment, S-C)[Cp(PNMent) NiPPh3] PF6 shows a distortion intermediate between the ene-allyl and diene types, while the two cyclopentadienyl ligands of [{(L-Ment, S-C)-[Cp(PNMent) Ni]}(2) dppe](PF6)(2) have intermediate and diene distortions, respectively. According to the temperature dependent NMR spectra of (L-Ment, S-C)-[Cp(PNMent) NiPPh3] PF6 and [{(L-Ment, S-C)[Cp(PNMent) Ni]}(2) dppe](PF6)(2) two different conformations of the tether in the Cp(PNMent) Ni system could be frozen out at low temperatures. [GRAPHICS] .