  We investigate the structural and transport properties of vacancy-ordered
monoclinic superconducting $\mathrm{TiO}$ thin films grown by molecular beam
epitaxy. The evolution of the crystal structure during growth is monitored by
in-situ synchrotron X-ray diffraction. Long-range ordering of Ti and O
vacancies in the disordered cubic phase stabilizes the vacancy-ordered
monoclinic TiO phase. The reduced structural disorder arising from
vacancy-ordering is correlated with a superconductor-metal transition (SMT) in
contrast to the superconductor-insulator transition (SIT) observed in cubic
TiO, orthorhombic $Ti_2O_3$, and the Magneli $\gamma-Ti_3O_5$ and
$\gamma-Ti_4O_7$ phase. Magnetoresistance measurements for the SIT phases
indicate superconducting fluctuations persisting in the normal phase. These
results confirm the role of disorder related to Ti and O vacancies and
structural inhomogeneity in determining the electronic properties of the normal
state of titanium oxide-based superconductors.
