Mechanochemical-reaction additive, mechanochemical method, ligand compound, and complex

A ligand compound (Ly) or salt thereof represented by formulas (La1) to (La5), (Lb1) to (Lb4), or (Lc1) to (Lc22) below:

• wherein in the formulas (La1) to (La5), na1, na2, na4, and na5 are each independently a number of repeating units of the polyoxyethylene chain and are 10 or more and 1000 or less;
• in the formulas (Lb1) to (Lb4), nb1 to nb6 are each independently a number of repeating units of the polyoxyethylene chain and are 8 or more and 1000 or less;
• in the formulas (Lc1) to (Lc22), nc1 to nc30 are each independently a number of repeating units of the polyoxyethylene chain and are 10 or more and 1000 or less;
• Me is a methyl group, iPr is an isopropyl group, X− is a monovalent anion and is F−, Cl−, Br−, I−, or BF4−;
• and
• in the formulas (La1) to (La5), (Lb1) to (Lb4), or (Lc1) to (Lc22), one or more alkyl groups having 1 to 6 carbon atoms may be bonded to a ring.