The occurrence of antiferromagnetism (AFM) in k-(ET) 2 X can be understood within an effective 1/2-filled band with dimers of ET molecules containing one hole each. We argue that while this effective model can describe the presence of AFM, a complete description for these materials requires the correct carrier density of one-half per molecule. For dimerized and strongly frustrated 1/4-filled lattices we show that a singletpaired statecoexisting with charge ordering occurs that we have termed the paired electron crystal (PEC). Here we investigate the 1/4-filled model on a dimerized lattice, showing regions where AFM, PEC, and the Wigner-crystal occur. We point out the need to go beyond quantum spin liquid concepts for highly frustrated materials such as k-(ET) 2 Cu 2 (CN) 3 and b 0 -EtMe 3 Sb[Pd(dmit) 2 ] 2 which we believe are PECs at low temperatures.