$\begin{array}{1 1}(a)\;\text{Nitrito-N-pentaammine cobalt (III) chloride}\\(b)\;\text{Nitrito-N-pentaammine cobalt (II) chloride}\\(c)\;\text{Pentaammine nitrito-N-cobalt (II) chloride}\\(d)\;\text{Pentaammine nitrito-N-cobalt (III) chloride}\end{array}$