A coordination complex, lithium hepta(i-butyl)silsesquioxane trisilanolate (1; Li-T-7), a stable intermediate in silsesquioxane (SQ) syntheses, was successfully isolated in 65% yield and found to be highly soluble in nonpolar solvents such as hexane. The structure of Li-T-7 was confirmed by NMR, IR spectroscopy, matrix-assisted laser desorption ionization time-of-flight mass spectrometry, electrospray ionization mass spectrometry, and computational simulation, providing detailed elucidation of the intermolecular self-association of the SQ cage with a box-shaped Li6O6 polyhedron through strong coordination bonds. After acid treatment, Li-T-7 undergoes lithium-proton cationic ex- change, yielding hepta(i-butyl)silsesquioxane trisilanol (2; H-T-7) quantitatively. The high yield of H-T-7 seems to be influenced by Li-O bonding in the Li-T-7 complex that affects the selective formation of hepta(i-butyl)silsesquioxane trisilanolate and the bulky i-butyl groups which may prevent decomposition or SQcage-rearrangement even at reflux under alkaline conditions. Single-crystal X-ray crystallography confirms the presence of the dumbbell-shaped SQpartial cages through strong intermolecular hydrogen bonds. Interestingly, lowering the polarity of the reaction solution by adding dichloromethane results in formation of the cubic octa(i-butyl)silsesquioxane (3; T-8) cage in a good yield (47%), which is isolated by crystallization from the reaction solution.