Synthesis, Crystal Structure, and Magnetic Studies of Oxo-Centered Trinuclear Chromium(III) Complexes: [Cr3(μ3-O)(μ2-PhCOO)6(H2O)3]NO3· 4H2O·2CH3OH, a Case of Spin-Frustrated System, and [Cr3(μ3-O)- (μ2-PhCOO)2(μ2-OCH2CH3)2(bpy)2(NCS )3], a New Type of [Cr3O] Core | Publicación