A salt selected from: maleic acid salt of (R) -3- (4- (7H-pyrrolo [2,3-d] pyrimidin-4-yl) -1H-pyrazol-1-yl) -3-cyclopentylpropanonitrile; (R) -3- (4- (7H-pyrrolo [2,3-d] pyrimidin-4-yl) -1H-pyrazol-1-yl) -3-cyclopentylpropanonitrile sulfuric acid salt; and phosphoric acid salt of (R) -3- (4- (7 H -pyrrolo [2,3-d] pyrimidin-4-yl) -1 H -pyrazol-1-yl) -3-cyclopentylpropanonitrile.Una sal seleccionada de: sal de ácido maleico de (R)-3-(4-(7H-pirrolo[2,3-d]pirimidin-4-il)-1H-pirazol-1-il)-3-ciclopentilpropanonitrilo; sal de ácido sulfúrico de (R)-3-(4-(7H-pirrolo[2,3-d]pirimidin-4-il)-1H-pirazol-1-il)-3-ciclopentilpropanonitrilo; y sal de ácido fosfórico de (R)-3-(4-(7H-pirrolo[2,3-d]pirimidin-4-il)-1H-pirazol-1-il)-3-ciclopentilpropanonitrilo.