Protonation of 1,4-bis(alkylamino)benzo[g]phthalazine. Crystal structure of di{1,4-bis-(3-methoxypropylamino)-3(2)H-benzo[g]phthalazinium} tetrachlorocobaltate monohydrate

Abstract

Reaction of the monohydrochloride of 1,4-bis-(3-methoxypropylamino)benzo[g]phthalazine (3′a) with cobalt(II) dichloride in neutral medium afforded a new salt of di-{1,4-bis-(3-methoxypropylamino)-3(2)H-benzo[g]phthalazinium}²⁺CoCl₄^2–H₂O (4), the structure of which has been determined by X-ray methods. It crystallizes in the space group P with a= 15.0008(10), b= 13.0621(8), c= 12.1465(8)Å, α= 100.515(6), β= 107.268(4), and γ= 92.687(7), Z= 2. The structure was solved by Patterson methods and refined by least-squares to R 0.074. The structure consists of dimeric (3-methoxypropylamino)-3(2)H-benzo[g]phthalazinium cations held one with each other and both with the anions and the water molecule by a network of hydrogen bonds and piling up along the a axis in a group of four molecules. The u.v., i.r., ¹H, and ¹³C n.m.r. spectroscopic data of the parent monohydrochloride (3′a) which are now reported for the first time, compared with those corresponding to the free base (3a), are also in agreement with the protonation of the heteroaromatic ring of 1,4-bis(alkylamino)benzo[g]phthalazine.