Comparison of two MnIVMnIV-bis-μ-oxo complexes {MnIV (N4(6-Me-DPEN))]2(μ-O)2}2+ and {MnIV (N4(6-Me-DPPN))]2(μ-O)2}2+

The addition of tert-butyl hydroperoxide ((BuOOH)-Bu-t) to two structurally related Mn-II complexes containing N,N-bis(6-methyl-2-pyridylmethyl)ethane-1,2-diamine (6-Me-DPEN) and N,N-bis(6-methyl-2-pyridylmethyl)propane-1,2-diamine (6-Me-DPPN) results in the formation of high-valent bis-oxo complexes, namely di-mu-oxido-bis{[N,N-bis(6-methyl-2-pyridylmethyl)ethane- 1,2-diamine] manganese (II)}(Mn - Mn) bis(tetraphenylborate) dihydrate, [Mn(C16H22N4)(2)O-2](C24H20B)(2)center dot 2H(2)O or [Mn-IV(N-4(6-Me-DPEN))](2)(mu-O)(2)}-(2BPh(4))(2H(2)O) (1) and di-mu-oxido-bis{[N,N-bis(6-methyl-2-pyridylmethyl)-propane- 1 ,3 -diamine] mang anese (II) }(Mn - Mn) bis(tetraphenylborate) diethyl ether disolvate, [Mn(C17H24N4)(2)O-2](C24H20B)(2)center dot 2C(4)H(10)O or {[Mn-IV(N-4(6-MeDPPN))](2)(mu-O)(2)}(2BPh(4))(2Et(2)O) (2). Complexes 1 and 2 both contain the 'diamond core' motif found previously in a number of iron, copper, and manganese high-valent bis-oxo compounds. The flexibility in the propyl linker in the ligand scaffold of 2, as compared to that of the ethyl linker in 1, results in more elongated Mn-N bonds, as one would expect. The Mn-Mn distances and Mn -O bond lengths support an Mn-IV oxidation state assignment for the Mn ions in both 1 and 2. The angles around the Mn centers are consistent with the local pseudo-octahedral geometry.