If I want to name a spin state with 12 unpaired electrons, what is the correct name? Tredecim is the latin name for thirteen, but tredecimet sounds odd.
I have seen multiplicity 13 referred to as simply a 13-let. This #-let nomenclature is sometimes used for high multiplicities (e.g. higher than 10).
I would go for the Greek form and call it trisdecatet. Or should it be with a k, trisdekatet?