title: Reductive nitrosylation and proton-assisted bridge splitting of a (mu-oxo)dimanganese(III) complex derived from a polypyridine ligand with one carboxamide group.
abstract: Aerobic oxidation of the Mn(II) complex [Mn(Papy3)(H2O)](ClO4) (1, PaPy3- is the anion of the designed ligand N,N-bis(2-pyridylmethyl)amine-N-ethyl-2-pyridine-2-carboxamide) in acetonitrile affords the (mu-oxo)dimanganese(III) complex [(Mn(PaPy3))2(mu-O)](ClO4)2 (3) in high yield. The unsupported single oxo bridge between the two high-spin Mn(III) centers in 3 is readily cleaved upon addition of proton sources such as phenol, acetic acid, and benzoic acid, and complexes of the type [Mn(PaPy3)(L)](ClO4) (5, L = PhO-; 6, L = AcO-; 7, L = BzO-) are formed. The basicity of the bridge is evident by the fact that simple addition of methanol to a solution of 3 in acetonitrile affords the methoxide complex [Mn(PaPy3)(OMe)](ClO4) (4). The structures of 3-5 and 7 have been determined. Passage of NO through a solution of 3 in acetonitrile produces the [Mn-NO]6 nitrosyl [Mn(PaPy3)(NO)](ClO4) (2) via reductive nitrosylation. Complexes 4-7 also afford the [Mn-NO]6 nitrosyl 2 upon reaction with NO. In the latter case, the anionic O-based ligands (such as MeO- and PhO-) act as built-in bases and promote reductive nitrosylation of the Mn(III) complexes.
authors.affiliation: Department of Chemistry and Biochemistry, University of California, Santa Cruz, California 95064, USA.
authors.forename: Kaushik
authors.initials: K
authors.lastname: Ghosh
authors.forename: Aura A
authors.initials: AA
authors.lastname: Eroy-Reveles
authors.forename: Marilyn M
authors.initials: MM
authors.lastname: Olmstead
authors.forename: Pradip K
authors.initials: PK
authors.lastname: Mascharak
mesh_terms: D018360:Crystallography, X-Ray; D009682:Magnetic Resonance Spectroscopy; D008280:Magnetics; D008345:Manganese / Q000737:chemistry*; D008958:Models, Molecular; D009569:Nitric Oxide / Q000737:chemistry; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D010084:Oxidation-Reduction; D010472:Perchlorates / Q000138:chemical synthesis* / Q000737:chemistry; D011725:Pyridines / Q000138:chemical synthesis* / Q000737:chemistry; D013056:Spectrophotometry, Ultraviolet; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D009942:Organometallic Compounds; D010472:Perchlorates; D011725:Pyridines; D009569:Nitric Oxide; D008345:Manganese