Ligand reactivity in diarylamido/Bis(phosphine) PNP complexes of Mn(CO)3 and Re(CO)3

Abstract

The syntheses of meridionally ligated trlcarbonyl complexes (PNP)Mn(CO)3 and (PNP)Re(CO)3 are described (PNP= [2-P(CHMe2)2-4-MeC6H3] 2N-). Cyclic voltammograms show reversible one-electron redox couples for both parent compounds (-0.34 V vs Cp2Fe 0/+ for (PNP)Mn(CO)3, -0.25 V vs Cp2Fe 0/+ for (PNP)Re(CO)3), and chemical oxidation with AgOTf results in formation of the corresponding paramagnetic triflate salts [(PNP)Mn(CO)3]OTf and [(PNP)Re(CO)3]OTf. Electron paramagnetic resonance spectra and computational results indicate that this event is primarily ligand centered; allylation of the organic ligand moiety of [(PNP)Mn(CO)3]OTf with allyltrlbutylstannane Is consistent with this assignment. The oxidation (PNP)Mn(CO)3 to [(PNP)Mn(CO) 3]OTf results in a shift in average CO stretching frequency of 30 cm-1; protonation of (PNP)Mn(CO)3 with TfOH to form [(PNHP)Mn(CO)3]OTf results In a similar magnitude shift. © 2009 American Chemical Society.