NOVELTY - A metal complex contains metal ions chosen from dicarboxylate ion (I), and metal ion which belongs to group 13 of periodic table.    USE - Metal complex is used for adsorbent and occlusion material for adsorbing and occluding carbon dioxide, hydrogen, carbon monoxide, oxygen, nitrogen, 1-4C hydrocarbon, noble gas, hydrogen sulfide, ammonia, sulfur oxide, nitrogen oxide, siloxane and organic vapor in gas storage apparatus for gas motor vehicle, and separation material for separating methane, carbon dioxide and hydrogen, carbon dioxide and nitrogen, carbon dioxide, ethylene and carbon dioxide, methane, ethane and ethane, ethylene and propane, propene, and air and methane (all claimed).    ADVANTAGE - The metal complex has excellent gas-adsorption performance, gas occlusion capacity, and gas-separation performance.    DETAILED DESCRIPTION - A metal complex contains metal ions chosen from dicarboxylate ion of formula (I), and metal ion which belongs to group 13 of periodic table.    R1,R2=optionally substituted alkyl, H, halo, alkoxy, formyl, acyloxy, alkoxycarbonyl, nitro, cyano, amino, monoalkyl amino, dialkylamino, or acylamino;and    A=phenylene or optionally substituted ethenylene.    INDEPENDENT CLAIMS are included for the following:    (1) adsorbent, which consists of metal complex;    (2) occlusion material (12), which consists of metal complex;    (3) gas storage apparatus, which consists of gas occlusion space in the inside of a pressure-resistant container in which airtight holding is possible, and equipped with entrance and exit of gas occlusion material internally to gas occlusion space;    (4) separation material, which consists of metal complex; and    (5) separation method, which involves contacting the metal complex and mixed gas under pressure of 0.01-10 Mpa using the separation material.    (6) preparation of compound of formula(I).    DESCRIPTION OF DRAWING(S) - The drawing shows a schematic view of gas motor vehicle.    High pressure regulator (9)    Mixer (10)    Engine (11)    Occlusion material (12)    Gas motor vehicle (20)