Iodine-containing compound

1. A compound represented by formula (3):

wherein

X 1 is an n1-valent siloxane group;

R 21 is H, F, Cl, CH 3 , CF 3 , or O(CF 2 ) p3 F;

R 22 is —R 26 —OCO— wherein R 26 is bonded to X 1 ;

R 23 is H or F;

R 24 is H, F, an aryl group, —COOR 30 , or an alkyl group optionally substituted with fluorine;

R 25 is H, F, an aryl group, —COOR 30 , or an alkyl group optionally substituted with fluorine;

R 26 is a single bond or an alkylene group optionally substituted with fluorine;

R 30 is H or an alkyl group;

p3 is an integer of 1 to 10; and

n1 is an integer of 1 to 10,

wherein the siloxane group is represented by the following formula:

—(SiR 27 2 —O) q —SiR 27 2 —,

—SiR 28 r R 29 3-r , or

(R a SiO 1.5 ) t

wherein

R 27 , each independently at each occurrence, is a hydrogen atom or an alkyl group;

R 28 , each independently at each occurrence, is —O—(SiR 27 2 —O) s —SiR 27 3 —;

R 29 is a single bond;

R a , each independently at each occurrence, is R b or R c , provided that

at least one R a is R b ,

R b is a single bond, and

R c is a hydrogen atom or alkyl;

q is an integer of 1 to 20;

r is an integer of 1 to 3;

s is an integer of 0 to 20; and

t is any integer.

2. A polymerization initiator comprising the compound according to claim 1 .