CRYSTAL-STRUCTURES OF 2 POLYMORPHIC MODIFICATIONS OF TRANS-DIISOTHIOCYANATO-BIS-(ETHYLENEDIAMINE)NICKEL(II) [NI(C2H8N2)2(NCS)2]

The x-ray crystal structure of Ni(en)2(NCS)2 (I) is redetermined and that of its metastable polymorphic modification (II) is determined. The refined constants of I are a = 10.176(2), b = 8.203(2), c = 8.791(2) angstrom, beta = 120.99(2)-degrees, V = 629.1(3) angstrom, space group P2(1)/a, Z = 2, d(calc) = 1.558 g/cm3. Crystals of II are monoclinic, a 6.047(2), b = 7.340(2), c = 14.365(3) angstrom, beta = 91.90(2)-degrees, V = 637.2 Angstrom3, space group P2(1), Z = 2, d(calc) = 1.538 g/cm3. The metals in the complexes have octahedral coordination. The ethylenediamine ligands are in the gauche conformation. The complexes in both structures have the KK' conformation. The total van der Waals intermolecular interaction energy is determined for both modifications. A crystallographic link between the structures of I and II is demonstrated.