3 research outputs found
Metal–Ligand Cooperation as Key in Formation of Dearomatized Ni<sup>II</sup>–H Pincer Complexes and in Their Reactivity toward CO and CO<sub>2</sub>
The
unique synthesis and reactivity of [(<sup>R</sup>PNP*)ÂNiH]
complexes (<b>1a</b>,<b>b</b>), based on metal–ligand
cooperation (MLC), are presented (<sup>R</sup>PNP* = deprotonated
PNP ligand, R = <sup>i</sup>Pr, <sup>t</sup>Bu). Unexpectedly, the
dearomatized complexes <b>1a</b>,<b>b</b> were obtained
by reduction of the dicationic complexes [(<sup>R</sup>PNP)ÂNiÂ(MeCN)]Â(BF<sub>4</sub>)<sub>2</sub> with sodium amalgam or by reaction of the free
ligand with Ni<sup>0</sup>(COD)<sub>2</sub>. Complex <b>1b</b> reacts with CO via MLC, to give a rare case of a distorted-octahedral
PNP-based pincer complex, the Ni(0) complex <b>3b</b>. Complexes <b>1a</b>,<b>b</b> also react with CO<sub>2</sub> via MLC to
form a rare example of η<sup>1</sup> binding of CO<sub>2</sub> to nickel, complexes <b>4a</b>,<b>b</b>. An unusual
CO<sub>2</sub> cleavage process by complex <b>4b</b>, involving
C–O and C–P cleavage and C–C bond formation,
led to the Ni–CO complex <b>3b</b> and to the new complex
[(P<sup>i</sup>Pr<sub>2</sub>NC<sub>2</sub>O<sub>2</sub>)ÂNiÂ(PÂ(O)<sup>i</sup>Pr<sub>2</sub>)] (<b>5b</b>). All complexes have been
fully characterized by NMR and X-ray crystallography
Highly Selective, Efficient Deoxygenative Hydrogenation of Amides Catalyzed by a Manganese Pincer Complex via Metal–Ligand Cooperation
Deoxygenative
hydrogenation of amides to amines homogeneously catalyzed
by a complex of an Earth-abundant metal is presented. This manganese-catalyzed
reaction features high efficiency and selectivity. A plausible reaction
mechanism, involving metal–ligand cooperation of the manganese
pincer complex, is proposed based on NMR studies and relevant stoichiometric
reactions
Highly Selective, Efficient Deoxygenative Hydrogenation of Amides Catalyzed by a Manganese Pincer Complex via Metal–Ligand Cooperation
Deoxygenative
hydrogenation of amides to amines homogeneously catalyzed
by a complex of an Earth-abundant metal is presented. This manganese-catalyzed
reaction features high efficiency and selectivity. A plausible reaction
mechanism, involving metal–ligand cooperation of the manganese
pincer complex, is proposed based on NMR studies and relevant stoichiometric
reactions