Complex sentence: Al-Rikabi tried but failed to get the Iraqi cell of the Ba'ath Party to break away from the National Command, and on 15 June 1961 he was expelled from the party.
Split into simpler sentences: Al-Rikabi tried to get the Iraqi-cell of the Ba'ath Party to break away from the National Command, in this he failed. And on 15 June 1961 he was expelled from the party.