Redox polymerizable composition with photolabile transition metal complexes

A polymerizable composition comprising a polymerizable ethylenically unsaturated component, and a redox initiation system comprising:

• a) an oxidizing agent,
• b) a reducing agent, and
• c) a photolabile transition metal complex of the formula:
• wherein
• Rphoto is a photolabile group;
• M+ is a transition metal that participates in a redox cycle;
• each X1 and X2 is independently selected from —N—, —S—, and —O—;
• each X3 and X4 is independently selected from the group consisting of —NR1—, and —S—;
• each R1 is independently selected from the group consisting of:
• H, alkyl, cycloalkyl, heterocycloalkyl, arylalkyl, heteroarylalkyl, alkoxy, halo, formyl, hydroxyl, acyl, aryloxy, alkylthio, amino, alkylamino, arylalkylamino, disubstituted amino, acylamino, acyloxy, ester, amide, and carboxyalkyl;
• each adjacent pair of R1 and R2 optionally independently form a heterocycloalkyl or heteroaryl group with respective heteroatom X3 or X4;
• each of R2, R3, R4, R5, R6, and R7 is independently selected from the group consisting of:
• H, alkyl, alkenyl, alkynyl, cycloalkyl, cycloalkylalkyl, cycloalkylalkenyl, cycloalkylalkynyl, heterocyclo, heterocycloalkyl, heterocycloalkenyl, heterocycloalkynyl, aryl, arylalkyl, arylalkenyl, arylalkynyl, heteroaryl, heteroarylalkyl, heteroarylalkenyl, heteroarylalkynyl, alkoxy, halo, mercapto, azido, cyano, formyl, carboxylic acid, carboxyalkyl, hydroxyl, nitro, acyl, aryloxy, alkylthio, amino, alkylamino, arylalkylamino, disubstituted amino, acylamino, acyloxy, ester, amide, sulfoxyl, sulfonyl, sulfonate, sulfonic acid, sulfonamide, urea, alkoxylacylamino, and aminoacyloxy;
• with the proviso that R3 is absent when R1 and R2 form a heteroaryl group with respective heteroatom X3—X4;
• R4 and R5 optionally together form oxo;
• or R6 and R7 optionally together form oxo;
• x is from 1 to 2;
• and y is from 1 to 3;
• or a salt thereof.