Preparation of a conjugated tautomer of 1,14:7,8-diethenotetrapyrido-[2,1,6-de:2′,1′,6′-gh:2″,1″,6″-kl:2‴,1‴,6‴na][1,3,5,8,10,12]hexa-azacyclotetradecine and its metal derivatives