The structural properties of a series of scandium inorganic acid derivatives were determined. The reaction of Sc-0 with concentrated aqueous hydrochloric acid led to the isolation of [(H2O)(5)Sc(mu-OH)](2)4Cl center dot 2H(2)O (1). Compound 1 was modified with a series of inorganic acids (i.e., HNO3, H3PO4, and H2SO4) at room temperature and found to form {[(H2O)(4)Sc(kappa(2)-NO3)(mu-OH)]NO3}(2) (2a), [(H2O)(4)Sc(x2-NO3)(2)]NO3 center dot H2O (2b) (at reflux temperatures), {6[H] [Sc(mu-PO4) (PO4)](6)}(n) (3), and [H] [Sc(mu(3)-SO4)(2)]center dot 2H(2)O (4a). Additional organosulfonic acid derivatives were investigated, including tosylic acid (H-OTs) to yield {[(H2O)(4)Sc(OTs)(2)]OTs}center dot 2H(2)O (4b) in H2O and [(DMSO)(3)Sc-(OTs)(3)] (4c) in dimethyl sulfoxide and triflic acid (H-OTf) to form [Sc(H2O)(8)]OTf3 (4d). Other organic acid modifications of 1 were also investigated, and the final structures were determined to be {([(H2O)(2)Sc(mu-OAc)(2)]Cl)(6)}(n) (5) from acetic acid (H-OAc) and [Sc(mu-TFA)(3)Sc(mu-TFA)(3)](n) (6) from trifluoroacetic acid (H-TEA). In addition to single-crystal X-ray structures, the compounds were identified by solid-state and solution-state Sc-45 nuclear magnetic resonance spectroscopic studies.