No abstract

No abstract

Bis(para-toluidinium), tetrachlorocuprate and bis(para-chloroanilinium)2 tetrachlorocuprate crystallize in a perovskite-related layer structure. The former crystallizes in an orthorhombic unit cell with a = 6.91 1 A, b = 7.052A and c = 33.182A. It undergoes a thermochromic first order phase transition from a yellow low temperature phase to a dark orange high temperature phase at T = 300 i. 3 K with a IO" thermal hysteresis. The latter compound undergoes two thermochromic transitions expressed by the 294 K 214Krelation.Orange Phase (I) -Yellow Phase (11) +Green Phase (111). Both compounds are ferromagnetic at low temperture with exchange interactions J / k = 17.5" and 20" for the two compounds respectively.

The behaviour of 3,5-diamino-4-phenylazopyrazole (1) toward isothiocyanates, acrylonitrile and ethyl ethoxymethylenecyanoacetate is investigated. An improved synthesis of 4-unsubstituted-3,5-diaminopyrazoles by an arylazo removal reaction is also reported.

No abstract