title: Polymorphism of dinitro[tris(2-aminoethyl)amine]cobalt(III) chloride.
abstract: Three polymorphs of bis(nitrito-κN)[tris(2-aminoethyl)amine-κ(4)N,N',N'',N''']cobalt(III) chloride, [Co(NO2)2(C6H18N4)]Cl, have been structurally characterized in the 100-300 K temperature range. Two orthorhombic polymorphs are related by a solid-state enantiotropic order-disorder k2 phase transition at ca 152 K. The third, monoclinic, polymorph crystallizes as a nonmerohedral twin. In the structure of the high-temperature (300 K) orthorhombic polymorph, the Co(III) complex cation resides on a crystallographic mirror plane, whereas the Cl(-) anion occupies a crystallographic twofold axis. In the unit cell of the monoclinic polymorph, the cationic Co(III) complex is in a general position, whose charge is balanced by two halves of two Cl(-) anions, each residing on a crystallographic twofold axis.
authors.affiliation: Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, Wisconsin 53706, USA.
authors.forename: Ilia A
authors.initials: IA
authors.lastname: Guzei
authors.affiliation: Department of Chemistry, University of Johannesburg, PO Box 524, Auckland Park, 2006, South Africa.
authors.forename: Charmaine
authors.initials: C
authors.lastname: Arderne
mesh_terms: D000588:Amines / Q000737:chemistry*; D003035:Cobalt / Q000737:chemistry*; D056831:Coordination Complexes / Q000737:chemistry*; D003460:Crystallization; D007477:Ions / Q000737:chemistry*
chemical_list: D000588:Amines; D056831:Coordination Complexes; D007477:Ions; C000602692:dinitro(tris(2-aminoethyl)amine)cobalt(III) chloride; D003035:Cobalt
keywords: DFT calculations; cobalt(III) complex; disorder; polymorphism; single-crystal X-ray analysis; solid-state phase transition; tris(2-aminoethyl)amine; twinning