First principles electronic structure calculations guided by energetic and magnetic principles of stability are conducted to predict and investigate a series of yttrium doped alkali clusters with a compact icosahedral structure and a large spin magnetic moment. The energetic stability of the YM12 (M = K, Rb and Cs) species lies on the nature of their electronic configuration and is a result of the controlled hybridization of the 4d-Y levels with the sp-alkali states. Further, the integrity of the YK12 is found to be conserved in a (YK12)(2) dimer attesting for its potential as a magnetic building block for nanostructure materials. (C) 2013 Elsevier B. V. All rights reserved.