wɪð sˈiːsiəm flˈʊɹɹaɪd, sˌiːˈɛs ˈɛf, ðə sˈiː ˈɛf fˈaɪv mˈaɪnəs ˈænaɪən ɪz fˈɔːɹmd, wˌɪtʃ hɐz ɐ skwˈɛɹ pɪɹˈæmɪdəl stɹˈʌktʃɚ sˈɪmɪlɚ tə ðɪ ˌaɪsoʊlɪktɹˈɑːnɪk klˈoːɹiːn pˈɛntɐflˌʊɹɹaɪd, sˌiːˈɛl ˈɛf fˈaɪv ænd bɹˈoʊmaɪn pˈɛntɐflˌʊɹɹaɪd, bˌiːˈɑːɹ ˈɛf fˈaɪv.
With caesium fluoride, CsF, the SeF5− anion is formed, which has a square pyramidal structure similar to the isoelectronic chlorine pentafluoride, ClF5 and bromine pentafluoride, BrF5.