Metal complex, adsorbent, separating material, and 1, 3-butadiene separation method

A metal complex consisting of:

• a dicarboxylic acid compound (I) represented by the following general formula (I):
• wherein X represents a carbon atom or nitrogen atom, Y represents a hydrogen atom, optionally substituted alkyl group having 1 to 4 carbon atoms, alkenyl group having 2 to 4 carbon atoms, alkoxy group having 1 to 4 carbon atoms, formyl group, acyloxy group having 2 to 4 carbon atoms, hydroxyl group, alkoxycarbonyl group having 2 to 4 carbon atoms, nitro group, cyano group, amino group, monoalkylamino group having 1 to 4 carbon atoms, dialkylamino group having 2 to 4 carbon atoms, acylamino group having 2 to 4 carbon atoms, sulfo group, sulfonate group or halogen atom in the case X represents a carbon atom or Y is not present in the case X represents a nitrogen atom, and R1, R2 and R3 respectively and independently represent a hydrogen atom, optionally substituted alkyl group having 1 to 4 carbon atoms or halogen atom;
• an ion of at least one type of metal selected from the group consisting of beryllium, magnesium, calcium, strontium, barium, titanium, vanadium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, copper, zinc and cadmium;
• and,
• a dipyridyl compound (II) represented by the following general formula (II):
• L-Z-L (II)
• wherein L is represented by any of the following formulas:
• wherein R4, R5, R6 and R7 respectively and independently represent a hydrogen atom, alkyl group having 1 to 4 carbon atoms or a halogen atom, and Z represents —CR8R9—CR10R11— (wherein R8, R9, R10 and R11 respectively and independently represent a hydrogen atom, alkyl group having 1 to 4 carbon atoms, hydroxyl group or halogen atom), an alkylene group having 3 to 4 carbon atoms, —CH═CH—, —C≡C—, —S—S—, —N═N—, —O—CH2—, —NH—CH2—or —NHCO—);
• wherein two or more different types of the dipyridyl compound (II) are contained as the dipyridyl compound (II), and only one type of the dicarboxylic acid compound (I) is contained as the dicarboxylic acid compound (I), and
• wherein the metal complex has a three-dimensional structure that is a multiply interpenetrating pseudo-diamondoid framework.