Valence delocalization in a strongly coupled (Kc = 1014) molecule-bridged cyanodiiron(III,II) species. Chemical Communications (Cambridge, United Kingdom), 16:1701--1702, 1998. [PUMA: bridged bridged;iron bridged;valence comproportionation const cyano delocalization dinuclear iron prepn;mixed pyrimidyltetrazine valent]