A detailed analysis of the intrinsic (1)Delta Pt-195((37/35))Cl) and (1)Delta Pt-195(O-18/16) isotope 128.8 MHz Pt-195 NMR profiles of the series of kinetically inert [PtCl6-n(OH)(n)](2-) (n = 1-5) anions generated in strongly alkaline aqueous solutions shows that each Pt-195 NMR resonance of the [(PtCl6-n)-Cl-35/37((16/18))OH)(n)](2-) (n = 1-5) anions is resolved only into [(6 - n) + 1 for n = 1-5] Cl-35/37 isotopologues at 293 K. Evidently, the greater trans influence of the hydroxido ligand in the order OH(-) > Cl(-) > H2O in [PtCl6-n(OH)(n)](2-) (n = 1-5) complexes results in somewhat longer Pt-Cl bond displacements trans to the hydroxido ligands, resulting in the absence of isotopomer effects in the [PtCl6-n(OH)n](2-) (n = 1-5) anions in contrast to that observed in the corresponding [PtCl6-n(H2O)n](2-n))(-) (n = 1-5) complexes. In suitably (18)O-enriched sodium hydroxide solutions, additional intrinsic (1)Delta Pt-195(O-18/16) isotope effects are remarkably well-resolved into unique isotopologue- and isotopomer-based Pt-195 NMR profiles, ascribable to the higher trans influence of the OH- ligand. The consequent significantly shorter Pt-OH bonds in these anions emphasize (16/18)O isotopomer effects in the Pt-195 NMR peaks of [(PtCl6-n)-Cl-35/37((OH)-O-16/18)(n)](2-) (n = 1-5) for magnetically nonequivalent ((OH)-O-16/18 isotopomers statistically possible in some isotopologues. These Pt-195 NMR profiles constitute unique NMR "fingerprints", useful for the unambiguous assignment of the series of [PtCl6-n(OH)(n)](2-) anions including their possible cis/trans/fac/mer stereoisomers in such solutions, without a need for accurate chemical shift measurements.