Polycyclic aromatic hydrocarbons have emerged as an exciting class of materials with the report of superconductivity in alkali doped picene with Tc=18 K. However, due to poor crystallinity and multiphase samples the confirmation of the putative superconducting phase has been problematical. We recently devised an alternative synthetic route to making such systems using reduction chemistry of polycyclic aromatic hydrocarbons which has resulted in the synthesis of a new family of tuneable magnetic organic materials, the triphenylides M2(C18H12)2(DME), where M=K,Rb,Cs and DME=1,2-dimethoxyethane. Although these are not superconductors, they do show intriguing magnetic properties with unusually large exchange couplings. Crucially their ground states are currently unknown and here we propose a muSR study of this system with the aim of elucidating its low temperature magnetic properties