Bis(N,N-dimethyl-1,3-propanediamine)bis(thiocyanato-N)nickel(II), NiL₂(NCS)₂, and its Solid-State Isomer [L = NH₂(CH₂)₃N(CH₃)₂]

The coordination polyhedron about the Ni^II atom in NiL₂(NCS)₂, (1), where L = NH₂(CH₂)₃N(CH₃)₂, is a distorted octahedron with the two thiocyanate N and the two unsubstituted N atoms of the ligand defining the equatorial plane; the two dimethylated N atoms occupy trans-axial positions. The six-membered chelate rings are in stable chair conformations. 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.

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