Oxidations of N,N′-disubstituted o-phenylenediamine in the presence of metal ions and the crystal structure of N,N′- dimethylbenzimidazolium perchlorate, pyridine-bis(o -benzosemiquinonediimine)cobalt(III) chloride and bis(pyridine)(N,N′-bistoluene-p-sulfonyl-o-phenylenediiminato)-copper(II)