The syntheses, structures, and magnetic properties of the compounds of formula [Fe-III(sal(2)trien)](2)[Mn-2(II)(ox)(3)]center dot 4H(2)O center dot C3H7NO (1) and [In-III(sal(2)trien)](2)[Mn-2(II)(ox)(3)]center dot 3H(2)O center dot CH3OH (2) are reported The structure presents a homometallic 2D honeycomb anionic layer formed by Mn-II ions linked through oxalate ligands and a cationic double layer of [Fe(sal(2)trien)](+) or [In(sal(2)trien)](+) complexes intercalated between the 2D oxalate network. The magnetic properties and Mossbauer spectroscopy of 1 indicate the coexistence of a magnetic ordering of the Mn(II) oxalate network that behaves as a weak ferromagnet and a gradual spin crossover of the intercalated [Fe(sal(2)trien)](+) complexes.