Molecular and Crystal Structure of Sildenafil Base

Abstract

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 6 O 4 S. The compound crystallizes in the monoclinic system, space group P2 1 /c with the unit cell parameters a = 17:273(1), b=17:0710(8), c=8:3171(4) Å , b =99:326(2), Z = 4, V = 2420:0(3) Å 3 . A comparison with the known crystal structures of sildenafil citrate monohydrate and sildenafil saccharinate is also presented.