Formation and Reactivity of Transient Phosphanoxyl Manganese Complexes

Formation of thermally unstable complexes [Mn­(CO)2CpMe(R2PO-TEMP)] (Cp = cyclopentadienyl; Me = methyl; TEMP = 2,2,6,6-tetramethyl-piperidin-1-oxyl) is presented in this experimental and theoretical study; in case of R = Cy 31P NMR spectroscopic evidence is provided. Mechanistic details of the product formation and decomposition, due to a homolytic O–N bond cleavage, are revealed by high-level density functional theory calculations. Insights into stability and spin density distribution of transient phosphanoxyl complexes [Mn­(CO)2CpMe(R2PO·)] and preliminary results on the acidity of related complexes [Mn­(CO)2CpMe(R2P–OH)] and [W­(CO)5(R2P–OH)] toward TEMP–H are presented.