These findings demonstrate that alkyl chain flexibility enables diverse crystal packing, with significant variations in cubane unit arrangement across polymorphs (Fig. ). Despite these differences, the tetranuclear cages exhibit nearly identical, slightly distorted cubic structures (Ru•••B = 4.79-4.83 Å), resembling the structure of a previously reported cyanoborate-bridged Cr-carbonyl complex [{Cr(CO)3(B(CN)4)}4] 4-. 9 Powder X-ray diffraction (PXRD) analysis revealed that 2a obtained via neat photoirradiation of 1a appeared to be a mixture of the β-form and other unknown forms, possibly a benzene solvate. The 2a formed via photoirradiation in methanol solution exhibited poor crystallinity, as indicated by the presence of only a few PXRD peaks. These structural insights provide foundational data for potential application of this method in film formation. In summary, UV photoirradiation of organometallic ILs quantitatively yielded solid tetranuclear cubane-type complexes. This molecular design uses coordinating anions that function as both IL counter-anions and bridging ligands in the metal complexes. The solvent-free reaction was more efficient and higher-yielding compared to solution-phase synthesis. Furthermore, structural analysis revealed that the alkyl chain flexibility led to diverse crystal packing in the cubane complexes. This study extends our IL-based photofabrication method for coordination compounds to the synthesis of cage complexes. In contrast to the B(CN)₄⁻ anion, the limited coordination and flexibility of the substituent in the BR(CN)₃⁻ anion likely facilitate cage complex formation, highlighting the importance of anion design. Our ongoing research explores extending this solvent-free approach to synthesize diverse metal complexes.