We report the synthesis and emission properties of some europium compounds, which are highly luminescent under UV excitation, formed by the tetrakis complex anion of [Eu(dbm)4]− type with three different counter cations: N(C2H5)4+, P(C6H5)4+ and As(C6H5)4+. For (N(C2H5)4)[Eu(dbm)4], only one Eu3+ site, site (a), was observed with an emission lifetime of 0.301ms and an evaluated quantum efficiency of 27.0% at 77K. The presence of the P(C6H5)4+ or As(C6H5)4+ cations in the salts causes a decrease of the lifetime and the quantum efficiency of the Eu3+ ions occupying the site (a). Moreover, steric effects resulting from the incorporation of the larger counter ions into a crystal structure lead to a formation of another site, in which Eu3+ ions have significantly longer lifetimes and higher quantum efficiencies compared to the site (a), equal to 0.829ms and 41% for (P(C6H5)4)[Eu(dbm)4], and 0.815ms and 35% for (As(C6H5)4)[Eu(dbm)4], respectively.