ðiːz klˈʌstɚz ɑːɹ kənsˈɪdɚd "ᵻlˈɛktɹɑːndᵻfˈɪʃənt," ðæt ˈɪz, ðeɪ duːnˌɑːt fˈɑːloʊ ðɪ ɑːktˈɛt ɹˈuːl bɪkˈʌz ðə mˈɑːlɪkjˌuːlz lˈæk səfˈɪʃənt ᵻlˈɛktɹɑːnz tə fˈɔːɹm fˈoːɹ tˈuːsˈɛntɚd, tˈuːᵻlˈɛktɹɑːn bˈɑːndz ɚɹˈaʊnd ˈiːtʃ kˈɑːɹbən ˈæɾəm, ɪn kˈɑːntɹæst tə mˈoʊst ɔːɹɡˈænɪk kˈɑːmpaʊndz.
These clusters are considered "electron-deficient," that is, they do not follow the octet rule because the molecules lack sufficient electrons to form four 2-centered, 2-electron bonds around each carbon atom, in contrast to most organic compounds.