Question

Write the IUPAC names of the following coordination compounds:
i) \([Pt(NH_3)_2ClNO_2]\)
ii) \([Co(NH_3)_5(CO_3)]Cl\)
iii) \([Ni(CO)_4]\)
iv) \([Co(NH_3)_5ONO]^{2+}\) (1+1+1+1)

Hint:

Name ligands alphabetically then the metal with its oxidation state; remember \(NO_2\) bonded through N is nitrito-N (nitro) while ONO bonded through O is nitrito-O.

Answer 1

Step 1 (naming convention): Ligands cited alphabetically, then metal with oxidation number; anionic ligands take an -o ending (chloride to chlorido, carbonate to carbonato). Linkage isomers of \(NO_2^-\) are distinguished: \(-NO_2\) (N-bonded) is nitrito-N (nitro), \(-ONO\) (O-bonded) is nitrito-O (nitrito).

Step 2, part i: \([Pt(NH_3)_2ClNO_2]\). Sum of charges \(= 0\), ammine \(0\), chlorido \(-1\), nitro \(-1\), so Pt is \(+2\). Reading ligands a-c-n: Diamminechloridonitrito-N-platinum(II).

Step 3, part ii: \([Co(NH_3)_5(CO_3)]Cl\). The neutral molecule carries one \(Cl^-\) outside, hence the cation is \(+1\); with five neutral ammines and carbonato \((-2)\), Co \(= +3\): Pentaamminecarbonatocobalt(III) chloride.

Step 4, part iii: \([Ni(CO)_4]\) is a neutral carbonyl; CO is neutral, so Ni is zero-valent: Tetracarbonylnickel(0).

Step 5, part iv: \([Co(NH_3)_5ONO]^{2+}\). Overall \(+2\); five ammines are neutral and the O-bonded \(ONO\) is \(-1\), giving Co \(= +3\): Pentaamminenitrito-O-cobalt(III) ion.