Molybdenum(VI) Peroxo α-Amino Acid Complexes: Synthesis, Spectra, and Properties of MoO(O2)2(α-aa)(H2O) for α-aa = Glycine, Alanine, Proline, Valine, Leucine, Serine, Asparagine, Glutamine, and Glutamic Acid. X-ray Crystal Structures of the Glycine, Alanine, and Proline Compounds