Abstract: A solid-state composition having the general formula CuxAnLyZ, where: A is CO or an olefin and n=0 or n>0; L is an electrically neutral ligand and O<y<0; and Z is an anion bearing a charge x-. The solid-state composition can advantageously adsorb CO or an olefin in the presence of water.

Abstract: A solid state composition is provided having the formula Cu(A).sub.n Z, where A is CO or olefin, n>1 and Z is a unitary or composite monovalent anion. Further provided are an apparatus adapted to adsorb and a method for adsorbing an adsorbate A from a fluid mixture. The apparatus and method employ an adsorbent having the formula Cu(A), Z, where A is CO or olefin, n>0 and Z is a unitary or composite monovalent anion. Z can be selected from the group consisting of: a) X.sup.- where X.sup.- is BF.sub.4.sup.-,PF.sub.6.sup.- or SbF.sub.6.sup.- ; b) (Al.sub.x (OR).sub.y).sup.- where R is fluoroalkyl or perfluoroalkyl, and x is 0 and y is 1, or x is 1 and y is 4; c) (RCO.sub.2).sup.- where R is alkyl, fluoroalkyl, perfluoroalkyl, aryl, fluoroaryl or perfluoroaryl; d) (RSO.sub.3).sup.- where R is alkyl, fluoroalkyl, perfluoroalkyl, aryl, fluoroaryl or perfluoroaryl; e) (H(RCO.sub.2).sub.2).sup.- where R is alkyl, fluoroalkyl, perfluoroalkyl, aryl, fluoroaryl or perfluoroaryl; f) (H(RSO.sub.3).sub.2).sup.