β-Diketiminato Nickel(I) Complexes with Very Weak Ligation Allowing for H2 and N2 Activation

Reaction of [L tBu NiBr] (L tBu = [HC(C(CMe 3 )NC 6 H 3 ( i Pr) 2 ) 2 ] − ) with KC 8 in toluene solution yields the complex [L tBu Ni(toluene)], 1, where toluene is bound in a η 2 mode via a C═C unit of the aromatic ring, as revealed by single-crystal X-ray crystallography and DFT calculations (B3LYP/6-31G*). Performing the same reaction in hexane as the solvent did not lead to a traceable product, so that the β-diketiminato ligand system was changed from L tBu to the less bulky L Me (L Me = [HC(CMeNC 6 H 3 ( i Pr) 2 ) 2 ] − ). Reduction of [L Me NiBr] 2 with KC 8 in diethyl ether led to [L Me Ni] 2, 2, with intramolecular Ni−aryl interactions, while employment of [L Me Ni(μ-Br) 2 Li(thf) 2 ] as a precursor for a reaction with KC 8 in OEt 2 led to the complex [L Me Ni(μ-Br)Li(thf) 2 ] 2, 3 . Both complexes 2 and 3 could be fully characterized, also with the aid of XRD, and their reactivity with respect to H 2 and N 2 was examined. It turned out that they oxidatively add H 2 to give the known compound [L Me Ni(μ-H)] 2, I, while the reaction with N 2 provides the dinitrogen complex [(L Me Ni) 2 (N 2 )], 4 .