1,3-bis(dicyanomethylene)squarate

Chemfm 1 3 bis dicyanomethylene squarate 2neg.svg

1,3-Bis(dicyanomethylene)squarate is a divalent anion with chemical formula C
10
N
4
O2−
2
or ((N≡C−)2C=)2(C4O2)2−. It is one of the pseudo-oxocarbon anions, as it can be described as a derivative of the squarate oxocarbon anion C
4
O2−
4
through the replacement of two opposite oxygen atoms by dicyanomethylene groups =C(−C≡N)2.

The anion can be obtained by reacting squaric acid with aniline to form the diester 1,3-dianiline squarate (a yellow solid), before treating the diester with malononitrile (N≡C−)2CH2 and sodium ethoxide to give the disodium tetrahydrate salt 2Na+·C
10
N
4
O2−
2
·4H2O, an orange water-soluble solid. The hydrated salt loses the water below 100 °C, but the resulting anhydrous salt is stable up to 400 °C.[1] Reaction of the sodium salt with salts of other cations in ethanol affords the following salts:[1]

Nuclear magnetic resonance shows that the aromatic character of the squarate core is retained.[1]

See also[]

References[]

  1. ^ a b c Vanessa E. de Oliveira, Gustavo S. de Carvalho, Maria I. Yoshida, Claudio L. Donnici, Nivaldo L. Speziali, Renata Diniz and Luiz Fernando C. de Oliveira (2009), "Bis(dicyanomethylene)squarate squaraines in their 1,2- and 1,3-forms: Synthesis, crystal structure and spectroscopic study of compounds containing alkali metals and tetrabutylammonium ions". Journal of Molecular Structure Volume 936, Issues 1–3, Pages 239–249 doi:10.1016/j.molstruc.2009.08.002