or 1; when t is 1, A is a bridging group joined to at least one of X, Y or J, preferably X and J; q is 1 or 2; m is the oxidation state of M minus q minus s if Q is a monovalent anion, m is (the oxidation state of M???q???s)/2, if Q is a bivalent anion or m is (the oxidation state of M???q???s)/3 if Q is a trivalent anion, preferably m is an integer from 1 to 3, s is 1, 2 or 3, preferably 1 or 2.