NOVELTY - A metal complex comprising metal ion chosen from magnesium ion, calcium ion, aluminum ion, chromium ion, molybdenum ion, tungsten ion, manganese ion, iron ion, ruthenium ion, rhodium ion, nickel ion, palladium ion, zinc ion, and cadmium ion is obtained by reacting dicarboxylic acid compound (I) and organic ligand (I) in which bidentate coordination is carried out.    USE - Metal complex is used for e.g. occlusion material for occluding carbon dioxide, hydrogen, carbon monoxide, oxygen, nitrogen, 1-4C hydrocarbon, noble gas, hydrogen sulfide, ammonia, steam and organic vapor, and separation material for separating carbon dioxide, hydrogen, carbon monoxide, oxygen, nitrogen, 1-4C hydrocarbon, noble gas, hydrogen sulfide, ammonia, sulfur oxide, nitrogen oxide, siloxane, steam and organic vapor and separating methane, carbon dioxide and hydrogen, carbon dioxide and nitrogen, carbon dioxide and ethylene, methane and ethane, ethylene and propane, propene or air and methane (all claimed). Uses include but are not limited to adsorbent for deodorizing and exhaust gas treatment, activated carbon material for air purification, desulfurization, denitration and toxic substance removal.    ADVANTAGE - The metal complex has excellent gas occlusion capacity and gas separation characteristics.    DETAILED DESCRIPTION - A metal complex comprising metal ion chosen from magnesium ion, calcium ion, aluminum ion, chromium ion, molybdenum ion, tungsten ion, manganese ion, iron ion, ruthenium ion, rhodium ion, nickel ion, palladium ion, zinc ion, and cadmium ion is obtained by reacting dicarboxylic acid compound of formula (I) and organic ligand of formula (II) in which bidentate coordination is carried out.    R1-R4=H, or alkyl, alkoxy, formyl, acyloxy or alkoxycarbonyl (all optionally substituted by nitro, cyano, amino, monoalkylamino, dialkylamino, acylamino or halo);    X=methine or nitrogen;and    R5-R12=H, halo, or optionally substituted alkyl.    INDEPENDENT CLAIMS are included for the following:    (1) occlusion material;    (2) separation material; and    (3) manufacture of metal complex, which involves reacting dicarboxylic acid compound (I) and organic ligand (II) in solvent.