Me2NN]Co(eta6-toluene): O=O, N=N, and O=N bond cleavage provides beta-diketiminato cobalt mu-oxo and imido complexes

The synthesis and structure of a novel beta-diketiminato Co(I) arene adduct Me2NN]Co(eta6-toluene) (2) are described, that serves as a synthon to the reactive, "naked" 12-electron Me2NN]Co fragment via loss of toluene in its reactions with dioxygen, organoazides, and a nitrosobenzene. Exposure of 2 to dioxygen in ether leads to {Me2NN]Co}2(mu-O)2 (3), a rare example of a cobalt-oxo complex thermally stable at room temperature. The X-ray structure of 3 reveals a short Co-Co separation of 2.716(4) A and exhibits positional disorder for the bridging oxo groups; the predominant configuration contains oxygen atoms in square-planar sites with short Co-O distances (1.784(3) and 1.793(4) A). Reaction of 2 with organoazides N3R (R = 3,5-Me2C6H3 (Ar) or 1-adamantyl (Ad)) results in the formation of imido complexes whose structure depends on the nature of the azido substituent. The synthesis and structures of both {Me2NN]Co}2(mu-NAr)2 (4) with arylimido groups in tetrahedral bridging sites or the three-coordinate, 16-electron Me2NN]CoNAd (5) are described. The X-ray structure of terminal imide 5 reveals a short Co-N bond distance (1.624(4) A) and only somewhat bent imido linkage (Co-N-C = 161.5(3) degrees ) consistent with a significant degree of multiple bond character. Complex 2 cleaves the O=N bond of the nitrosobenzene O=NAr (Ar = 3,5-Me2C6H3) to form the binuclear oxo-imido complex {Me2NN]Co}2(mu-O)(mu-NAr) (6) that possesses a structure intermediate between square-planar 3 and tetrahedral 4 in which the Me2NN]Co fragments are mutually orthogonal.