The present invention relates to a bisphosphine ligand compound, a chromium compound prepared using same, an ethylene oligomerization catalyst system containing the chromium compound, and an ethylene oligomer preparing method, wherein the bisphosphine ligand compound is suitable for mass production and commercial processes, allows extremely high activity to be compatible with excellent economical benefit, and increases selectivity for ethylene oligomerization reaction, thereby being able to be used to manufacture 1-hexene and/or 1-octene at high yield.
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