Redox chemistry of the triplet complex (PNP)Co(I).
Reaction of PNPCo, where PNP is (tBu2PCH2SiMe2)2N-, with the persistent radical galvinoxyl, G, gives PNPCoIIG, a nonplanar S = 3/2 species. Reaction with PhCH2Cl or with 0.5 mol I2 gives PNPCoX (X = Cl or I, respectively), but additional I2, seeking CoIII, gives instead oxidation at phosphorus: (tBu2P(I)CH2SiMe2NSiMe2CH2PtBu2)CoI2. Hydrogen-atom transfer reagents fail to give PNPCoH, but H2 gives instead PNPCo(H)2, a result rationalized thermodynamically based on DFT calculations. Multiple equiv of PhSiH3 give a product of Co(V), where N/SiPh and P/Si bonds have formed. N2CH(SiMe3) gives a 1:1 adduct of PNPCo, whose metric parameters suggest partial oxidation above CoI; N2CHPh gives a 1:1 adduct but with very different spectroscopic features. PhN3 reacts fast, via several intermediates detected below 0 degrees C, to finally release N2 and form a CoI product where one phosphorus has been oxidized, PN(P=NPh)Co. Whereas PNPCo(N3) resists loss of N2 on heating, one electron oxidation gives a rapid loss of N2, and the remaining nitride nitrogen is quickly incorporated into the chelate ligand, giving [tBu2PCH2SiMe2NSiMe2NP(tBu2)=CH2Co]. O2 or PhI=O generally gives products where one or both phosphorus centers are converted to its oxide, bonded to cobalt.
Ingleson
Michael J
MJ
Department of Chemistry, Indiana University, Bloomington, Indiana 47405, USA.
Pink
Maren
M
Fan
Hongjun
H
Caulton
Kenneth G
KG
D001559:Benzhydryl Compounds / Q000737:chemistry; D003035:Cobalt / Q000737:chemistry*; D018360:Crystallography, X-Ray; D008024:Ligands; D008956:Models, Chemical; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D009943:Organophosphorus Compounds / Q000737:chemistry*; D017646:Organosilicon Compounds / Q000737:chemistry*; D010084:Oxidation-Reduction; D013816:Thermodynamics
D001559:Benzhydryl Compounds; D008024:Ligands; D009942:Organometallic Compounds; D009943:Organophosphorus Compounds; D017646:Organosilicon Compounds; D003035:Cobalt; C020338:galvinoxyl