Manganese(II) tetraphenylporphyrin

[31004-82-7] C44H28MnN4 (MW 667.66) InChI = 1S/C44H28N4.Mn/c1-5-13-29(14-6-1)41-33-21-23-35(45-33)42(30-15-7-2-8-16-30)37-25-27-39(47-37)44(32-19-11-4-12-20-32)40-28-26-38(48-40)43(31-17-9-3-10-18-31)36-24-22-34(41)46-36;/h1-28H;/q-2;+2/b41-33-,41-34-,42-35-,42-37-,43-36-,43-38-,44-39-,44-40-; InChIKey = SEVKCRJDNPAWQG-DAJBKUBHSA-N (catalyst for aerobic oxidation of alkenes and alkanes; model heme analog) Alternative Names: Mn(II)TPP; 5,10,15,20-tetraphenyl-21H,23H-porphyrin manganese(II). Physical Data: unknown. Solubility: unknown. Form Obtained in: usually formed in situ; purple crystals as toluene solvate: Mn(II)TPP·2PhMe.1 Analysis of Reagent Purity: UV/Vis Spectroscopy; ESR Spectroscopy. Preparative Methods: Mn(II)TPP is generally made in situ via reduction of the more common and more stable Mn(III)(TPP)Cl species. It is also possible to directly insert Mn(II)TPP into a metal-free porphyrin. In-situ Chemical Reduction Method: Mn(III)(TPP)Cl (18 mg, 1 equiv) was dissolved in DCM (3 mL) and the solution was degassed and kept under an argon atmosphere. Tetra-n-butylammonium borohydride (78 mg, 12 equiv) was added as a solid and the mixture was stirred at room temperature and used in situ for subsequent reactions.2 Chromous Reduction Method: Chromium(II) acetylacetonate was added to a mixture of Mn(III)(TPP)Cl in refluxing toluene until the color of the solution changed from green to deep purple. The hot solution was filtered quickly through a medium frit and heptane was added. After 1 h, the resulting precipitate was filtered to afford the crude product. Recrystallization from hot toluene/heptane provided purple crystals of desired product in 55% yield (eq 1).1 (1) Manganese Insertion Method:  A mixture of tetraphenylporphyrin, manganese bromide (MnBr2), and Proton Sponge (N,N,N′,N′-tetramethylnaphthalene-1,8-diamine) in toluene and THF was heated until, upon acidification of a sample, the visible spectrum indicated lack of protonated free porphyrin at 750 nm. Degassed alumina was added and the solvents were carefully removed under reduced pressure. The desired product was obtained by column purification on a short alumina column, eluting with toluene/THF. Recrystallization from hot toluene/heptane provided purple crystals of desired product in 55% yield.1 Handling, Storage, and Precautions: unknown; recommend to form and use in situ.