Coordination Chemistry of Polynitriles, Part XII—Serendipitous Synthesis of the Octacyanofulvalenediide Dianion and Study of Its Coordination Chemistry with K+ and Ag+

The reaction of diazotetracyanocyclopentadiene with copper powder in the presence NEt4Cl yields, unexpectedly, besides known NEt4[C5H(CN)4] (3), NEt4 salt octacyanofulvalenediide (NEt4)2[C10(CN)8] (5), which can be transformed via AgNO3 to corresponding Ag+ (4), turn reacted KCl yield K+ 6. molecular and crystal structures 4–6 could determined, show a significantly twisted aromatic dianion uses all its nitrile groups for coordination metals; 4 6 form three-dimensional polymers fourfold coordinated eightfold cations.