NOVELTY - A metal complex is a porous metal complex comprising bivalent metal ion, terephthalic acid compound, 4,4'-bipyridyl compound, and 1-2C monocarboxylic acid compound. The composition ratio of terephthalic acid compound and monocarboxylic acid compound is 10:1-5000:1. In the diffraction pattern of metal complex obtained by powder X-ray diffraction measurement using copper-K ( alpha )-ray source with respect to metal complex, when total of the area of all diffraction peaks (2( theta )) within 5-15 degrees is set to 100%, the diffraction peaks (A and B) are within 8.5-9.5 degrees and 13-15 degrees , respectively.    USE - Metal complex is used in adsorbent and occlusion material and separation material for adsorbing, occluding and separating carbon dioxide, hydrogen, carbon monoxide, oxygen, nitrogen, 1-4C hydrocarbon, noble gas, hydrogen sulfide, ammonia, sulfur oxide, nitrogen oxide, siloxane, water vapor and organic vapor, and for separating methane and carbon dioxide, hydrogen and carbon dioxide, nitrogen and carbon dioxide, ethylene and carbon dioxide, methane and ethane, ethane and ethylene, propane and propene, nitrogen and oxygen, oxygen and argon, nitrogen and methane, and air and methane (all claimed) in air purification industry, desulfurization industry, and denitration industry.    ADVANTAGE - The metal complex has excellent durability, water resistance, stability at high temperatures and high humidity conditions, and high adsorption performance.    DETAILED DESCRIPTION - A metal complex is a porous metal complex comprising bivalent metal ion, optionally substituted terephthalic acid compound, optionally substituted 4,4'-bipyridyl compound, and 1-2C monocarboxylic acid compound. The composition ratio of terephthalic acid compound and monocarboxylic acid compound is 10:1-5000:1. In the diffraction pattern of the metal complex obtained by powder X-ray diffraction measurement using copper-K ( alpha )-ray source with respect to metal complex in a state in which solvent is removed from pores, when total of the area of all diffraction peaks (2( theta )) within 5-15 degrees is set to 100%, the diffraction peak (A) is within 8.5-9.5 degrees and diffraction peak (B) is within 13-15 degrees , and the total area is 40-75%. INDEPENDENT CLAIMS are included for the following:    (1) separation method; and    (2) manufacture of metal complex.