Question

Which one of the following has largest number of isomers ?
(a) [Ir(PR₃ )₂H(CO)]
(b) [Co(NH₃)₅Cl]²⁺
(c) [Ru(NH₃)₄Cl₂ ]⁺
(d) [Co(en)₂Cl₂ ]⁺ (R = alkyl group, en = ethylenediamine)

Answer 1

I think the answer is d.