Particularly noteworthy is gold forming ionic compounds with rubidium and caesium, in which it forms the auride ion (Au−) which also occurs in solvated form in liquid ammonia solution: here gold behaves as a pseudohalogen because its 5d106s1 configuration has one electron less than the quasi-closed shell 5d106s2 configuration of mercury.
pɚtˈɪkjʊlɚli nˈoʊtwɜːði ɪz ɡˈoʊld fˈɔːɹmɪŋ aɪˈɑːnɪk kˈɑːmpaʊndz wɪð ɹuːbˈɪdiəm ænd sˈiːsiəm, ɪnwˌɪtʃ ɪt fˈɔːɹmz ðɪ ˈɔːɹaɪd ˈaɪɑːn ˌoʊ mˈaɪnəs wˌɪtʃ ˈɔːlsoʊ əkˈɜːz ɪn sˈɑːlveɪɾᵻd fˈɔːɹm ɪn lˈɪkwɪd æmˈoʊniə səlˈuːʃən: hˈɪɹ ɡˈoʊld bᵻhˈeɪvz æz ɐ sˈuːdoʊhˌælədʒən bɪkˈʌz ɪts fˈaɪv dˈiː wˈʌnhˈʌndɹɪd sˈɪks ᵻz wˈʌn kənfˌɪɡjɚɹˈeɪʃən hɐz wˈʌn ᵻlˈɛktɹɑːn lˈɛs ðɐn ðə kwˈeɪzaɪklˈoʊzd ʃˈɛl fˈaɪv dˈiː wˈʌnhˈʌndɹɪd sˈɪks ᵻz tˈuː kənfˌɪɡjɚɹˈeɪʃən ʌv mˈɜːkjʊɹi.