Twinned low-temperature structures of tris(ethylenediamine)zinc(II) sulfate and tris(ethylenediamine)copper(II) sulfate.
Tris(ethylenediamine)zinc(II) sulfate, [Zn(C(2)H(8)N(2))(3)]SO(4), (I), undergoes a reversible solid-solid phase transition during cooling, accompanied by a lowering of the symmetry from high-trigonal P31c to low-trigonal P3 and by merohedral twinning. The molecular symmetries of the cation and anion change from 32 (D(3)) to 3 (C(3)). This lower symmetry allows an ordered sulfate anion and generates in the complex cation two independent N atoms with significantly different geometries. The twinning is the same as in the corresponding Ni complex [Jameson et al. (1982). Acta Cryst. B38, 3016-3020]. The low-temperature phase of tris(ethylenediamine)copper(II) sulfate, [Cu(C(2)H(8)N(2))(3)]SO(4), (II), has only triclinic symmetry and the unit-cell volume is doubled with respect to the room-temperature structure in P31c. (II) was refined as a nonmerohedral twin with five twin domains. The asymmetric unit contains two independent formula units, and all cations and anions are located on general positions with 1 (C(1)) symmetry. Both molecules of the Cu complex are in elongated octahedral geometries because of the Jahn-Teller effect. This is in contrast to an earlier publication, which describes the complex as a compressed octahedron [Bertini et al. (1979). J. Chem. Soc. Dalton Trans. pp. 1409-1414].
Bijvoet Center for Biomolecular Research, Crystal and Structural Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands. m.lutz@uu.nl
Martin
M
Lutz
D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray; D007477:Ions / Q000737:chemistry*; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D013237:Stereoisomerism; D013696:Temperature; D015032:Zinc / Q000737:chemistry*
D007477:Ions; D009942:Organometallic Compounds; C554373:tris(ethylenediamine)copper(II) sulfate; C554372:tris(ethylenediamine)zinc(II) sulfate; D003300:Copper; D015032:Zinc