A crystalline form II of (3aR, 5s, 6aS) -N- (3-methoxy-1,2,4-thiadiazol-5-yl) -5- (methyl (7H-pyrrolo [2,3- d]) pyrimidin-4-yl) amino) hexahydrocyclopenta [c] pyrrole-2 (1H) -formamide, characterized in that the crystal has a powder X-ray diffraction spectrum, which is obtained using Cu-Ka radiation and represented by an angle 2θ and an interplanar distance, in which there are characteristic peaks at 8.96 (9.87), 11.80 (7.50), 13.12 (6.74), 13.53 (6.54), 13 , 89 (6.37), 14.42 (6.14), 14.98 (5.91), 16.52 (5.36), 18.20 (4.87), 18.75 (4, 73), 19.15 (4.63), 19.72 (4.50), 20.82 (4.26), 22.05 (4.03), 22.52 (3.95), 22, 92 (3.88), 23.58 (3.77) and 27.04 (3.30).Una forma cristalina II de bisulfato de (3aR,5s,6aS)-N-(3-metoxil-1,2,4-tiadiazol-5-il)-5-(metil(7H-pirrolo[2,3- d]pirimidin-4-il)amino)hexahidrociclopenta[c]pirrol-2(1H)-formamida, caracterizada por que el cristal tiene un espectro de difracción de rayos X en polvo, que se obtiene usando radiación Cu-Ka y representado mediante un ángulo 2θ y una distancia interplanar, en la que hay picos característicos a 8,96 (9,87), 11,80 (7,50), 13,12 (6,74), 13,53 (6,54), 13,89 (6,37), 14,42 (6,14), 14,98 (5,91), 16,52 (5,36), 18,20 (4,87), 18,75 (4,73), 19,15 (4,63), 19,72 (4,50), 20,82 (4,26), 22,05 (4,03), 22,52 (3,95), 22,92 (3,88), 23,58 (3,77) y 27,04 (3,30).
