51321-10-9Relevant academic research and scientific papers
Synthesis, structure, and properties of [Mn(salpn)(EtOH)2](ClO4) and its aerobic oxidation product [Mn(salpn)O]2
Gohdes, Joel W.,Armstrong, William H.
, p. 368 - 373 (2008/10/08)
Preparation and isolation of the mononuclear MnIII complex [Mn(salpn)(EtOH)2](ClO4) (1a) (H2salpn = N,N′-bis(salicylidene)-1,3-diaminopropane) were accomplished by air oxidation of a solution containing H2salpn, NaOH, and Mn(ClO4)2·6H2O in MeOH/EtOH (1:1), followed by addition of Et2O. Compound 1a·EtOH·H2O crystallizes in the triclinic space group P1 with a = 11.649 (3) A?, b = 13.902 (6) A?, c = 19.849 (7) A?, α = 70.18 (2)°, β = 70.52 (2)°, γ = 60.33 (2)°, V = 2726 (2) A?3, and Z = 4. For 1a·EtOH·H2O there are two mononuclear MnIII complexes in the crystallographic asymmetric unit. The Mn-O and Mn-N distances for 1 are in good agreement with those found for other MnIII Schiff base complexes. The 1H NMR spectrum of 1 in CD3CN has well-resolved, paramagnetically shifted resonances at 19.8, 11.6, 7.4, -2.8, -24.8, -26.2, and -94.2 ppm, Compound 1 has a MnIII/II reduction potential of -0.154 V vs SSCE as measured by cyclic voltammetry in DMSO. Compound 1 was converted into [Mn2O2(salpn)2] (2) by air oxidation in basic MeOH followed by recrystallization from DMF. Alternatively, 2 can be prepared by air oxidation of Mn(salpn)(H2O) in pyridine, followed by crystallization from CH2Cl2/cyclohexane. Compound 2·2DMF crystallizes in the monoclinic space group P21/c with a = 10.722 (2) A?, b = 10.163 (3) A?, c = 17.564 (4) A?, β = 100.67 (2)°, V = 1890 (1) A?3, and Z = 2. Using an isotropic spin-exchange Hamiltonian ? = 2JS?1·S?2, variable-temperature magnetic data for 2 were fit well with a J value of -82 cm-1. The magnitude of J is significantly less than that for several other species containing the {Mn2O2}4+ core yet comparable to the value obtained for [Mn2O2(pic)2] (pic = 2-pyridinecarboxylate) (Inorg. Chem. 28, 4037). The reduction potential for 2 in (-0.39 V vs SSCE) for the IV,IV/IV,III couple is the lowest determined for a bis(μ-oxo)dimanganese complex.
