[en] This work is dedicated to investigations of structural and magnetic properties of the colloidal Fe/Fe_xO_y nanocubes (13 nm) and the Fe_xRh_100-x core/shell nanoparticles (2 nm). As compared with other works, where the measurements on oxidized nanoparticles were carried out, we additionally performed investigations on nanoparticles in an oxide free state. In order to make the measurements on oxide free particles possible, oxygen- and hydrogenplasma was used to remove the ligands and reduce the oxide shell of the Fe nanocubes. The oxide free Fe nanocubes were covered with a Ag/Pt protective coating to prevent them from new oxidation. This method allowed carrying out the magnetic measurements on oxide free Fe nanocubes. Micromagnetic simulations as well as simulations of the high frequency susceptibility were used for the data analysing. It was found that both the g-factor g=2.09±0.01 and the anisotropy constant K₄=(4.8±0.5).10⁴ J/m³ coincide with that of bulk iron. However, the saturation magnetization M_S(5 K)=(1.2±0.12).10⁶ A/m differs from the bulk value by 30%. The reduction by 30% compared to the bulk value in the case of nanoparticles may be caused by the following possible reasons: a) the presence of inner oxide layer (approx. 10 at.%) that cannot be reduced; b) the anti-parallel order between magnetic moments of iron core and magnetic moments of antiferomagnetic iron oxide; c) some structural changes of the surface after plasma treatment. The obtained damping parameter α=0.03±0.005 is ten times larger than that of the Fe layers as it is known for nanoparticles systems in general. The core/shell Fe_xRh_100-x nanoparticles (x=80,50) were produced under Ar-atmosphere and were sealed into a quartz tube to prevent oxidation. The analysis of g-factors shows that the value for the FePh nanoparticles with Fe-rich core is larger (g=2.08±0.01) than that for the nanoparticles with Rh-rich core and coincides within error bars with the g-factor of bulk iron (g=2.09). The analysis of anisotropy constants K_A and average magnetic moment per particle m gives also larger values for the given nanoparticles: K_A(T_B,SQUID=3.3 K)=2.20.10⁵ J/m³ and m=358.7 μ_B than for nanoparticles with Rh-rich core: K_A(T_B,SQUID=2.3 K)=2.07.10⁵ J/m³ and m=182.2 μ_B. The smallest values were obtained for the FeRh nanoparticles with Rh-rich core. These differences in the parameters are due to the alloy formation and canted order in the core/shell interface. (orig.)