Ligand Compound, Organochromium Compound and Catalyst Composition Comprising the Same

A ligand compound represented by Formula 1:

• in Formula 1,
• R1 to R4 are each independently a trialkylsilyl group, where the alkyl group is an alkyl group of 1 to 4 carbon atoms, and
• R5 is a substituent represented by any one of Formulae 2 to 4:
• in Formulae 2 to 4,
• X1 to X6 are each independently —(CR6R7)n—, —O— or —S—, where X1 to X5 are not —O— or —S— simultaneously, and n is an integer selected from 0 to 3,
• R6 and R7 are each independently hydrogen, an alkyl group of 1 to 5 carbon atoms, a trifluoroalkyl group of 1 to 5 carbon atoms, an aryl group of 6 to 10 carbon atoms, or —NR8R9,
• R8 and R9 are each independently hydrogen or an alkyl group of 1 to 5 carbon atoms, and
• * is a part bonded to N of Formula 1.