ja074378+_si_003.cif (37.58 kB)

# Redox Chemistry of the Triplet Complex (PNP)Co^{I}

dataset

posted on 2020-04-02, 13:40 authored by Michael J. Ingleson, Maren Pink, Hongjun Fan, Kenneth G. CaultonReaction of PNPCo, where PNP is (

^{t}^{}Bu_{2}PCH_{2}SiMe_{2})_{2}N^{-}, with the persistent radical galvinoxyl, G, gives PNPCo^{II}G, a nonplanar*S*=^{3}/_{2}species. Reaction with PhCH_{2}Cl or with 0.5 mol I_{2}gives PNPCoX (X = Cl or I, respectively), but additional I_{2}, seeking Co^{III}, gives instead oxidation at phosphorus: (^{t}^{}Bu_{2}P(I)CH_{2}SiMe_{2}NSiMe_{2}CH_{2}P^{t}^{}Bu_{2})CoI_{2}. Hydrogen-atom transfer reagents fail to give PNPCoH, but H_{2}gives instead PNPCo(H)_{2}, a result rationalized thermodynamically based on DFT calculations. Multiple equiv of PhSiH_{3}give a product of Co(V), where N/SiPh and P/Si bonds have formed. N_{2}CH(SiMe_{3}) gives a 1:1 adduct of PNPCo, whose metric parameters suggest partial oxidation above Co^{I}; N_{2}CHPh gives a 1:1 adduct but with very different spectroscopic features. PhN_{3}reacts fast, via several intermediates detected below 0 °C, to finally release N_{2}and form a Co^{I}product where one phosphorus has been oxidized, PN(PNPh)Co. Whereas PNPCo(N_{3}) resists loss of N_{2}on heating, one electron oxidation gives a rapid loss of N_{2}, and the remaining nitride nitrogen is quickly incorporated into the chelate ligand, giving [^{t}^{}Bu_{2}PCH_{2}SiMe_{2}NSiMe_{2}NP(^{t}^{}Bu_{2})CH_{2}Co]. O_{2}or PhIO generally gives products where one or both phosphorus centers are converted to its oxide, bonded to cobalt.