The Instability of Ni{N(SiMe3)2}2: A Fifty Year Old Transition Metal Silylamide Mystery

The characterization of the unstable Ni-II bis(silylamide) Ni{N(SiMe3)(2)}(2) (1), its THF complex Ni{N(SiMe3)(2)}(2)(THF) (2), and the stable bis(pyridine) derivative trans-Ni{N(SiMe3)(2)}(2)(py)(2) (3), is described. Both 1 and 2 decompose at ca. 25 degrees C to a tetrameric Ni-I species, [Ni{N(SiMe3)(2)}](4) (4), also obtainable from LiN(SiMe3)(2) and NiCl2(DME). Experimental and computational data indicate that the instability of 1 is likely due to ease of reduction of Ni-II to Ni-I and the stabilization of 4 through dispersion forces.