In view of the recent experimental observation of the existence of tetravalent Hg(IV) in HgF₄, a quantum chemical study of various trivalent group 12 M(III) fluoride complexes has been carried out. The M-F bonds in neutral MF₃ are relatively weak, making these species unlikely targets. Some additional stability can be obtained by dimerizing HgF₃ to Hg₂F₆, which has a doubly fluorine-bridged triplet ground state. Anionic [MF₄]⁻ and [MF₅]²⁻ species are found to be more stable toward F₂ elimination and M-F bond breaking than neutral MF₃.