In context of the growing interest to single molecule magnetism much attention has been attracted to an unique layered large vanadium cluster K6[VIV 15As6O42(H2O)]·8H2O (hereafter V15, left figure) containing 15 VIV ions strongly coupled through antiferromagnetic exchange to give low spin frustrated ground state. Studies of the adiabatic magnetization and quantum dynamics show that despite the absence of the barrier for spin reversal the V15 exhibits the hysteresis of magnetization of a purely molecule origin and thus can be referred to as nano-size (mesoscopic) system. Middle figure shows the pathways for the isotropic exchange interactions and the scheme of frustrated spin arrangement in the ground manifold.figureHere we present an overview of the concepts of single molecule magnetism and study of the magnetic properties and EPR of the fascinating V15 cluster. The model includes isotropic and antisymmetric (AS) exchange interaction resulting in non-collinear (canted) spin structure. It was found that the energy pattern is influenced by two parameters, namely, normal Dn and effective in-plane D┴ components of the AS exchange vector. The zero-field splitting is shown to depend mainly on the normal part of AS exchange as well as the positions of two low lying crossing points in the Zeeman pattern. This part of AS exchange affects the low field behavior of magnetization in perpendicular field. At the same time the gap in the avoided crossing point giving rise to a tunneling of magnetization is affected only by the in-plane AS exchange that gives rise to a smoothening of the low-temperature step in magnetization vs. field at 2.8 Tesla. The model provides perfect fit to the experimental data on staircase M(T, H) as shown in the right figure (solid line – theoretical modeling). We were able to find the key parameters of V15 cluster: isotropic exchange J = –0.855 cm –2, g-factor g┴= 1.94 and for the first time reliably estimate two components of the AS exchange, namely, Dn = –0.054 cm –1, and Dt = –0.238 cm –1 . We discuss low-temperature experimental data on high-frequency EPR (ν1 = 57.831 GHz and ν2 = 108 GHz) of V15 cluster at ultra-low temperature (T = 1 ÷ 4K). We conclude AS exchange is concluded to give a significant contribution to the linewidth in ν1 spectrum while the results show the importance of other mechanisms of broadening in ν2 spectrum.