Two Types of Intramolecular Lewis-Base Adducts with the [2-(Dimethylamino)ethyl]cyclopentadienyl Ligand: Synthesis and Crystal Structures of {η:η-C5H4[(CH2)2NMe2]}Ni-I and {η-μ-C5H4[(CH2)2NMe2]}(Me3P)Ni-InI2

The synthesis and reactivity of nickel complexes with the [2-(dimethylamino)ethyl]cyclopentadienyl ligand (CpN) are described. The reaction of NiBr2 with CpNLi leads to the new paramagnetic nickelocene derivative (Cp)2Ni (1), which has been characterized by 1H and 13C NMR, elemental analysis, and mass spectroscopy. Synproportionation of this complex with Ni(CO)4 affords quantitatively the dimeric nickel complex [Cp(CO)Ni]2 (2). Reductive cleavage of 2 with KC8 and trapping of the anionic intermediate with Me3SnCl gives the stannyl-nickel complex Cp(CO)Ni-SnMe3 (4). Reaction of 2 with Ga2Cl4 yields the gallium-nickel complex (η-μ-Cp)(CO)Ni-GaCl2 (7) with intramolecular coordination of the dimethylamino group to the gallium center. Oxidative cleavage of 2 with iodine and liberation of CO leads to the intramolecular chelate (η5:η1-CpN)Ni-I (3). The compounds (η-μ-Cp)(PR3)Ni-InI2 with R ) C6H5 (5) and CH3 (6) are obtained in good yields by insertion of low-valent indium halides InX (X ) Br, I) into the Ni-I bond of 3. X-ray diffraction determinations were carried out for 3 and 6, and for 6, a comparably short Ni-In distance of 241.80(7) pm was found.