Preparation, crystal and molecular structure of aquadichlorocaffeinecopper(II)

✍ Scribed by G. Bandoli; M.Cingi Biagini; D.A. Clemente; G. Rizzardi

• Publisher: Elsevier Science
• Year: 1976
• Tongue: English
• Weight: 689 KB
• Volume: 20
• Category: Article
• ISSN: 0020-1693
• DOI: 10.1016/s0020-1693(00)94093-3

✦ Synopsis

Preparation, crystal and molecular structure of aquadichlorocaffeinecopper(II), determined by threedimensional X-ray data, are reported. The darkish green crystals are orthorhombic, space group P212121 with cell dimensions: a = 16.370(9), b = 13.432(7), c = 5.814(6) a and Z = 4. The structure was solved by the heavy-atom method from 1221 reflections collected by counter, and refined by least-squares method to R = 0.028. The geometry around copper is tetragonal pyramidal distorted towards trigonal bipyramidal, the Czv symmetry being maintained. The caffeine imidazole nitrogen atom (Cu-N 1.

a), oxygen atom from water (Cu-0 1.96 A) and tram chlorine atoms (Cu-Cl(I) 2.32, Cu-Cl(2) 2.25 8) lie at the corners of an approximate squme as closest ligands to the copper. Through a screw-axis parallel to c, Cl(l) atom is placed at the apex of the pyramidal confguration (Cu-Cl(l)' 2.79 Ii); since only one chlorine atom forms a bridge between successive symmetry related copper atoms a polynuclear chain with alternating short and long Cu-Cl distances is formed. The single chain is further strengthened by Cl---HOH hydrogen bonds; moreover, symmetryrelated chains are held together by 0 ---HOH hydrogen bonds.