The crystal structure of LaC2 shows that it contains C2 units with a C-C bond length of 130.3 pm, which is longer than the C-C bond length in calcium carbide, 119.2 pm, which is close to that of ethyne.
ðə kɹˈɪstəl stɹˈʌktʃɚɹ ʌv lˌæ sˈiː tˈuː ʃˈoʊz ðˌɐɾɪt kəntˈeɪnz sˈiː tˈuː jˈuːnɪts wɪð ɐ sˈiːsˈiː bˈɑːnd lˈɛŋθ ʌv wˈʌnhˈʌndɹɪd θˈɜːɾi.θɹˈiː pˌiːˈɛm, wˌɪtʃ ɪz lˈɔŋɡɚ ðɐn ðə sˈiːsˈiː bˈɑːnd lˈɛŋθ ɪn kˈælsiəm kˈɑːɹbaɪd, wˈʌnhˈʌndɹɪd nˈaɪntiːn.tˈuː pˌiːˈɛm, wˌɪtʃ ɪz klˈoʊs tə ðæt ʌv ˈɛθaɪn.