| prov:value
| - wherein R23, R24, R25, R26, R27, and R28 are each independently selected from hydrogen, a hydrocarbon group, a silicon-containing group, a sulfur-containing group, an oxygen-containing group, a nitrogen-containing group, and a halogen-containing group, adjacent substituents of R23 to R28 are optionally bonded to each other to form a ring, M is a Group 4 transition metal, Y is carbon atom, Q is sel
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