  This work provides the first full set of vibrational and rotational spectral
data needed to aid in the detection of AlH$_3$OH$_2$, SiH$_3$OH, and
SiH$_3$NH$_2$ in astrophysical or simulated laboratory environments through the
use of quantum chemical computations at the CCSD(T)-F12b level of theory
employing quartic force fields for the three molecules of interest. Previous
work has shown that SiH$_3$OH and SiH$_3$NH$_2$ contain some of the strongest
bonds of the most abundant elements in space. AlH$_3$OH$_2$ also contains
highly abundant atoms and represents an intermediate along the reaction pathway
from H$_2$O and AlH$_3$ to AlH$_2$OH. All three of these molecules are also
polar with AlH$_3$OH$_2$ having the largest dipole of 4.58 D and the other two
having dipole moments in the 1.10-1.30 D range, large enough to allow for the
detection of these molecules in space through rotational spectroscopy. The
molecules also have substantial infrared intensities with many of the
frequencies being over 90 km mol$^{-1}$ and falling within the currently
uncertain 12-17 $\mu$m region of the spectrum. The most intense frequency for
AlH$_3$OH$_2$ is $\nu_9$ which has an intensity of 412 km mol$^{-1}$ at 777.0
cm$^{-1}$ (12.87 $\mu$m). SiH$-3$OH has an intensity of 183 km mol$^{-1}$ at
1007.8 cm$^{-1}$ (9.92 $\mu$m) for $\nu_5$, and SiH$_3$NH$_2$ has an intensity
of 215 km mol$^{-1}$ at 1000.0 cm$^{-1}$ (10.00 $\mu$m) for $\nu_7$.
