Molecular and crystal structure of sildenafil base

摘要

Sildenafil citrate monohydrate, well known as Viagra ?, is a drug for the treatment of erectile dysfunction. Here we present the X-ray crystal structure of the sildenafil base, C _(22)H _(30)N _6O _4S. The compound crystallizes in the monoclinic system, space group P21/c with the unit cell parameters a = 17:273(1), b=17:0710(8), c=8:3171(4) A°, β =99:326(2), Z = 4, V = 2420:0(3) A° ~3. A comparison with the known crystal structures of sildenafil citrate monohydrate and sildenafil saccharinate is also presented.