Accurate ab initio molecular orbital and density functional theories are used to study the structure of silyl isocyanate in the gas phase, in solution, and in the crystalline state. Calculations predict a linear backbone with a C-3v symmetry for both the gas phase and in solution. Model calculations on the dimer and the trimer yield markedly bent structures because of acid-base interactions between different silyl isocyanate units. This result explains the C-s bent geometry found for this compound in the crystalline state. Lewis acids are also found to yield bent structures upon complexation on both the nitrogen and the oxygen, the former type of interaction being more stabilizing than the latter.