I’ve recently enrolled in university and in my inorganic chemistry we were covering nomenclature as recommended by IUPAC of course. We never covered any examples where 2 different polyatomic groups which have 2 or more atoms that can coordinately bond, not talking about one ligand binding to central atom only once and without bridges. Any examples I find are either cyclic, bridging or have same previously described ligands. I have drawn an example picture below and here is my question:

Do you name it:

a) tetrachloridonitritothiocyanato-kN,kS-cobalt(II)

b) tertachlorido(nitrito-kN)(thiocyanato-kS)cobalt(II)

c) tertachloridonitriti-kN-thiocyanato-kS-cobalt(II)

d) as any of the above three with “-“ somewhere.

Or more generally when specifying with kappa do you write it after each name or at the end before central atom.

Quick disclaimer: I am not natively English, so sorry if i misspelled any of the names.

Thank you for the answer.

enter image description here

  • 1
    $\begingroup$ Some links for you: goldbook.iupac.org/terms/view/K03366 .... en.m.wikipedia.org/wiki/…. $\endgroup$ Commented Oct 20, 2021 at 10:42
  • $\begingroup$ Thank you for the resources, but i have read red book before asking and didn’t not find the definitive answer to my dilemma as most examples there are either cyclic or equal groups using bis to simplify it. $\endgroup$ Commented Oct 20, 2021 at 11:44

1 Answer 1


Based on Red Book's 4-page summary (vide infra), I suggest to proceed with these steps:

  • What is the central ion? It is cobalt(IV).
  • What are the ligands: a nitrite (then to be called nitrido), four chlorides (then to be called chlorido) and a thiocyanate. According to your drawing, the later binds to $\ce{Co}$ via sulfur, thus named with the kappa notation as thiocyanato-$\kappa$S.
  • Red Book's four page excerpt (vide infra, 2.3) then instructs to sort ligands alphabetically. In case of ligands occurring multiple times, prefixes are prepend which however do not alter the alphabetic sort established.

Thus, open to discussion tetrachloridonitridothiocyanato-$\kappa$S-cobalt(IV).


  1. I'm not sure about the hyphen set just before cobalt(IV) and welcome critique on this. Visually, I would perceive a form like tetrachloridonitridothiocyanato-$\kappa$Scobalt(IV) odd for the joining the italic S right prior to cobalt.

  2. From perspective of organic chemistry, thiocyanato-$\kappa$S reads like a layer of redundant information. There, if the group is not bound to the alkyl chain via sulfur, but via nitrogen (i.e., thiocyanato-$\kappa$N in parlance of Red Book), it would be called an isothiocyanate. Possibly Red Book's rules want this to prevent ambiguity.

  3. I know nitrosyl ligands ($\ce{NO}$) may bind either by oxygen, or nitrogen to transition metals in complexes. I'm not (yet) aware of experimental findings for an analogue isomerism for nitrite ($\ce{NO2}$) and thus assume one may skip the kappa notation for this ligand.

The references consulted for this preliminary answer are listed in the nomenclature section of chemistry.se's resources page; i.e., the brief guide and the 4-page summary of the Red Book.


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