L-1,3-PROPANEDIAMINE)BIS(THIOCYANATO-N)NICKEL(II), NIL2(NCS)(2), AND ITS SOLID-STATE ISOMER [L = NH2(CH2)(3)N(CH3)(2)]

The coordination polyhedron about the Ni-II atom in NiL2(NCS)2, (1), w here L = NH2(CH2)(3)N(CH3)2, is a distorted octahedron with the two th iocyanate N and the two unsubstituted N atoms of the ligand defining t he equatorial plane; the two dimethylated N atoms occupy trans-axial p ositions. The six-membered chelate rings are in stable chair conformat ions. Complex (1), [Ni(C5H14N2)(2)(NCS)(2)], undergoes a thermochromic solid-state phase transition producing an isomer, (2). With the cell volume of (2) approximately double that of (1) and the crystal system remaining triclinic, the space group of the isomer (2) is P1 or <P(1)o ver bar>.