Patent ID: 7732643

Claim:
A carbonyl compound represented by a formula (1): wherein R 1 represents a hydrogen atom, an optionally substituted C 1-10 alkyl group, an optionally substituted C 6-20 aryl group or an optionally substituted C 7-20 aralkyl group; R 2 , R 3 , R 4 and R 5 are the same or different and each independently represents a hydrogen atom, an optionally substituted C 1-10 alkyl group, an optionally substituted C 1-10 alkoxy group, an optionally substituted C 6-20 aryl group, an optionally substituted C 6-20 aryloxy group, an optionally substituted C 7-20 aralkyl group, an optionally substituted C 7-20 aralkyloxy group, a silyl group substituted with optionally substituted C 1-20 hydrocarbon group(s), or a C 1-20 hydrocarbon-substituted amino group; R 6 , R 7 , R 8 and R 9 are the same or different and each independently represents a hydrogen atom, a halogen atom, an optionally substituted C 1-10 alkyl group, an optionally substituted C 1-10 alkoxy group, an optionally substituted C 6-20 aryl group, an optionally substituted C 6-20 aryloxy group, an optionally substituted C 7-20 aralkyl group, an optionally substituted C 7-20 aralkyloxy group, a silyl group substituted with optionally substituted C 1-20 hydrocarbon group(s) or a C 1-20 hydrocarbon-substituted amino group, or the adjacent R 2 , R 3 , R 4 and R 5 and the adjacent R 6 , R 7 , R 8 and R 9 are linked to each other to form a benzene ring or a cycloalkylene ring; provided that 1) the positions of the double bonds of the cyclopentadiene ring are variable or the cyclopentadiene ring represents a mixture of compounds having double bonds at any positions, and 2) neither R 2 and R 3 nor R 4 and R 5 are linked to each other and taken together with the cyclopentadiene ring to form a fluorene ring or an indenyl ring.