Catalyst for synthesizing polyolefins

A method for producing an organometallic compound represented by formula (III)

• (in the formula, M, R1a, R1b, R2a, R2b, R6, R7, R8, R9, A1 and X have the meanings as set forth below), comprising:
• A process of reacting free bisphosphine monoxide (BPMO) represented by formula (I)
• (in the formula, R1a, R1b, R2a and R2b may be the same or different with each other, and independently represent a substituted or unsubstituted alkyl group having 1 to 14 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 14 carbon atoms, a substituted or unsubstituted biphenyl group or a substituted or unsubstituted aryl group;
• a pair of R1a and R1b and a pair of R2a and R2b may be bonded to form a ring structure;
• and A1 represents an arylene group, a monocyclic heteroarylene group, heterocyclic group, alkylene group having 1 to 2 carbon atoms, cycloalkylene group having 3 to 10 carbon atoms, alkenylene group having 2 to 8 carbon group, or cycloalkenylene group having 3 to 10 carbon atoms) and (1,5-cyclooctadiene) MR6Xa (M represents an element belonging to Group 10 in the periodic system;
• R6 represents alkyl group having 1 to 10 carbon atoms, alkenyl group or aryl group;
• and Xa represents a halogen atom);
• and
• A process of treating the generated (BPMO)(1,5-cyclooctadiene) MR6Xa complex with a metal salt represented by M2X (M2 represents a monovalent metal ion selected from Ag, Li, Na and K;
• and X represents a counteranion selected from SbF6, BPh4, BArF4, BF4 and PF6) and a compound represented by formula (2)
• (in the formula, R7, R8 and R9 independently represent a hydrogen atom, alkyl group having 1 to 4 carbon atoms or alkoxy group).