Hexafluoromanganate (IV), complex fluoride phosphor, and methods respectively for producing said products

A method for producing hexafluoromanganate (IV), comprising the steps of:

• inserting an anode and a cathode into a reaction liquid that includes a compound containing manganese having a valence of less than 4 and/or more than 4 and hydrogen fluoride;
• and passing an electrical current between the anode and cathode at a current density of from 100 to 1,000 A/m2,
• wherein a reactor in which the reaction liquid is placed is partitioned with a diaphragm into a first chamber for use as an anode chamber in which the anode is inserted and a second chamber for use as a cathode chamber in which the cathode is inserted, and current is passed between the anode and cathode, and
• wherein
• a reaction liquid that includes a compound containing manganese having a valence greater than 4 and hydrogen fluoride is placed in the cathode chamber, and a solution that includes hydrogen fluoride and does not include manganese is placed in the anode chamber, or
• a reaction liquid that includes a compound containing manganese having a valence of less than 4 and hydrogen fluoride is placed in the anode chamber, and a reaction liquid that includes a compound containing manganese having a valence greater than 4 and hydrogen fluoride is placed in the cathode chamber.