The labile cationic aqua complex, Tp(iPr)Ru(OH2)(2)(THF).(OTf)(THF)(2), 2, containing the hydrotris(3,5-diisopropylpyrazolyl)borate ligand (Tp(iPr)), is prepared by protonolysis of the ruthenium pentahydride complex Tp(iPr)RuH(5), 1, with trifluoromethanesulfonic acid (TfOH) in THF. Treatment of 2 with various 2e and 4e donors results in displacement of the THF and aqua ligands to give Tp(iPr)Ru(OH2)(n)(L)(3-n).(OTf)(THF)(x), 3-6 (L= py, bipy, phen, pz(iPr)-H, PPh3, dppe, MeCN,(BuCN)-Bu-t, =C=C(H)Ph; n = 0-2), and thus, complex 2 serves as a versatile precursor for a variety of cationic ruthenium aqua complexes. X-ray crystallographic analysis of the di- (2, 3b,c) and monoaqua complexes (4c, 5) reveals ternary hydrogen-bonding networks among the aqua, OTf-, and THF fragments.