The IUPAC name for [(NH₃)₅ Cr– (OH) – Cr(NH₃)₅]5+ is a -hydroxo-bis (pentaammine dichromium) (5+) ion b -hydroxo-bis (decaamminedichromium) (5+) ion

[NH₃)₅Cr–(OH)–Cr(NH₃)₅]5+ -Prefix is for bridge ligand, hydroxo is the bridging ligand and thus is used before hydroxo. ‘bis’ is used when two groups are present. There are 5 ammine groups present for which ‘penta’ is used. The oxidation state of chromium is +3 and thus (III) is used after that. Hence, the IUPAC name for the compound will be: -hydroxo-bis [(pentaamminechromium (III)]