The hemilabile [2-(dimethylamino)ethyl]cyclopentadienyl ligand and nickel:Preparation and structural analysis of new cationic and neutral complexes

Various new compounds containing the [2-(dimethylamino)ethyl]cyclopentadien yl (Cp-N) moiety coordinated to a nickel centre have been synthesized. A ne w derivative (Me3SiCpNiI)-Ni-N (1b) was obtained by a previously described pathway, while the reaction of its older analogue (CpNiI)-Ni-N (1a) with Tl [PF6] and the subsequent interception of the intermediate cation in THF wit h two equivalents of PPh3 or dmpe (Me2PCH2CH2PMe2) yielded the two ionic sp ecies [(CpNi)-Ni-N(PPh3)]+PF6- (4) and [(CpNi)-Ni-N(dmpe)]+PF6- (5), respec tively. The direct substitution of the halide functionality in la with MesM gBr (Mes = 2,4,6-trimethylphenyl) in THF gave the pentane-soluble neutral c omplex Cp(N)NiMes (6). Compounds Ib, 4, 5, and 6 were characterized by H-1, C-13, and P-31 (if phosphorous is present) NMR spectroscopy, elementary an alyis, mass spectrometry, and single crystal X-ray diffractometry, The mode l compounds [(CpNi)-Ni-N(PH3)](+) (CpNiMe)-Ni-N, (CpNiPh)-Ni-N, and [(CpNi) -Ni-N(OH2)](+) were further studied by DFT calculations at the B3LYP level of theory.