Chiral tungsten(IV) aqua-oxo-alkyne complexes, [Tp'W(O)(H2O)(RC=CR)][OTf] (R = H (1); R = Me (2)); (Tp' = hydridotris(3,5-dimethylpyrazolyl)borate; OTf = trifluoromethanesulfonate), have been prepared by halide abstraction from iodide precursors. These cationic complexes have been characterized with triflate as the counteranion. The tautomeric dihydroxo isomer has not been observed. The neutral triflate adduct Tp'W(O)-(OTf)(HC=CH) (3) has also been isolated. Cationic complexes 1 and 2 undergo deprotonation and isomerization when exposed to Al2O3 to give the dioxo-vinyl compounds Tp'W(O)(2)(CH=CH2) (6) and Tp'W(O)(2)[C(Me)= C(H)(Me)] (7), reflecting the conversion of the W-IV(OH)(RC=CR) fragment to W-VI(O)(RC=CHR). The presumed intermediates, neutral oxo-hydroxo compounds Tp'W(O)(OH)(RC=CR) (R = H (9); R = Me (10)), can be accessed by deprotonation of 1 or 2 with NaOH. Conversion of 9 to 6 was achieved thermally upon heating at 100 degrees C for 2 days. X-ray structural data have provided solid-state structures of bath the cationic aqua complex 2 and the dioxo-vinyl complex 6.