1379690-67-1Relevant articles and documents
Characterization and dioxygen reactivity of a new series of coordinatively unsaturated thiolate-ligated manganese(II) complexes
Coggins, Michael K.,Toledo, Santiago,Shaffer, Erika,Kaminsky, Werner,Shearer, Jason,Kovacs, Julie A.
, p. 6633 - 6644 (2012)
The synthesis, structural, and spectroscopic characterization of four new coordinatively unsaturated mononuclear thiolate-ligated manganese(II) complexes ([MnII(SMe2N4(6-Me-DPEN))](BF4) (1), [MnII(SMe2N4(6-Me-DPPN))](BPh 4)·MeCN (3), [MnII(SMe2N 4(2-QuinoPN))](PF6)·MeCN·Et2O (4), and [MnII(SMe2N4(6-H-DPEN)(MeOH)](BPh 4) (5)) is described, along with their magnetic, redox, and reactivity properties. These complexes are structurally related to recently reported [MnII(SMe2N4(2-QuinoEN))](PF 6) (2) (Coggins, M. K.; Kovacs, J. A. J. Am. Chem. Soc.2011, 133, 12470). Dioxygen addition to complexes 1-5 is shown to result in the formation of five new rare examples of Mn(III) dimers containing a single, unsupported oxo bridge: [MnIII(SMe2N4(6-Me-DPEN)] 2-(μ-O)(BF4)2·2MeOH (6), [Mn III(SMe2N4(QuinoEN)]2-(μ-O) (PF6)2·Et2O (7), [Mn III(SMe2N4(6-Me-DPPN)]2-(μ-O) (BPh4)2 (8), [MnIII(SMe2N 4(QuinoPN)]2-(μ-O)(BPh4)2 (9), and [MnIII(SMe2N4(6-H-DPEN)] 2-(μ-O)(PF6)2·2MeCN (10). Labeling studies show that the oxo atom is derived from 18O2. Ligand modifications, involving either the insertion of a methylene into the backbone or the placement of an ortho substituent on the N-heterocyclic amine, are shown to noticeably modulate the magnetic and reactivity properties. Fits to solid-state magnetic susceptibility data show that the Mn(III) ions of μ-oxo dimers 6-10 are moderately antiferromagnetically coupled, with coupling constants (2J) that fall within the expected range. Metastable intermediates, which ultimately convert to μ-oxo bridged 6 and 7, are observed in low-temperature reactions between 1 and 2 and dioxygen. Complexes 3-5, on the other hand, do not form observable intermediates, thus illustrating the effect that relatively minor ligand modifications have upon the stability of metastable dioxygen-derived species.