Formation of a tetranickel octacarbonyl cluster from the CO2 reaction of a zero-valent nickel monocarbonyl species

The reaction of a zerovalent nickel complex {Na}{(PNP)Ni(CO)} (1) with CO2(g) results in the formation of a tetrameric cluster complex {(PNCOONaP)Ni(CO)2}4 (2) as the major product along with {(PNP)Ni}2-μ-CO3-κ2O,O (3), {(PNP)Ni}2-μ-CO2-κ2C,O (4) and (PNP)Ni(CO) (5). A labelling experiment with 13CO2(g) reveals that not only the carbamate moeity but also the CO ligand in 2 originate from CO2(g). The formation of both a carbonyl species 2 and a carbonate species 3 indicates that nickel-mediated reductive disproportionation of CO2 occurs. Alternatively, a direct CO2 oxidative reaction of 1 occurs to produce {(PNP)Ni}2-μ-CO2-κ2C,O (4) in a minor pathway. The synthesis and characterization of 2 and other products are described herein. © 2016 the Partner Organisations6611sciescopu