Substitution and Reaction Chemistry of Cobalt Complexes Supported by [N₂P₂] Ligands

The coordination chemistry of mono- and divalent cobalt complexes supported by the monoanionic multidentate ligands, [N2P2] (where [N2P2] = tBuN(−)SiMe2N(CH2CH2PiPr2)2) and [N2P2tolyl] (where [N2P2tolyl] = MeC6H4N(−)SiMe2(CH2CH2PiPr2)2), is presented. The Co(II) halide complex [N2P2]CoI (2) serves as a precursor to the alkyl, hydride, and amide species [N2P2]CoMe (3), [N2P2]CoCH2SiMe3 (4), [N2P2]CoH (5), [N2P2]CoNHPh (10), and [N2P2]CoNHC6H4Me (11). Reduction of 2 results in the formation of a stable, monomeric Co(I) species, [N2P2]Co (6). Compound 6 can be trapped with CO to form either [N2P2]Co(CO) (7) or [tBuN(CO)SiMe2N(CH2CH2PiPr2)2]Co(CO)2 (8) depending on the number of equivalents of CO introduced. Compound 6 also serves as a precursor to transient Co(III) imido species. The Co(II) halide complex [N2P2tolyl]CoI (16) is synthesized through an analogues reaction to that of 2. Reduction of 16 results in the formation of [N2P2tolyl]Co (17), and differences in the coordination and reaction chemistry of 6 and 17 are described.