Dimorphism of zinc(II) dithizonate

Abstract

Zinc dithizonate, Zn(HDZ)₂, HDz = C₁₃H₁₁N₄S^-, has been found to occur in two crystalline modifications, the structure of one form ('α') having already been determined; its redetermination is reported here, together with that of the 'β' form. Crystals of the 'α' form are monoclinic, P2₁/c, a 7.887(3), b 22.40(1), c 15.324(6) Ǻ, β 92.82(3)°, Z 4; the structure has been refined by least squares to a residual of 0.061 for 2061 'observed' diffractometer reflections. The cell dimensions of the 'β' form are remarkably similar, but with an interchange of axes; crystals are monoclinic, P2₁/c, a 7.607(2), b 15.66(1), c 2276(1) Ǻ, β 94.97(3)°, Z 4, the structure being refined to a residual of 0.039 for 1846 'observed' reflections. The zinc environments in both structures are very similar, the zinc atoms being four-coordinate with a pair of similar N,S-chelating ligands about each. For the α form, Zn-S are 2.272(3), 2.271(3) A, S-Zn-S, 130.6(1)° Zn-N are 2.058(7), 2.083(6) °, N-Zn-N, 107.7(3)°, while the chelate N-Zn-S angles are 86.6(2), 86.8(2)°, and interligand N-Zn-S, 120.6(2), 126.0(2)°. For the ° form, Zn-S are 2.256(2), 2.270(2) A, S-Zn-S, 129.4(1)°; Zn-N are 2.064(5), 2.053(5) A, N-Zn-N, 107.4(2)°, while chelate N-Zn-S angles are 86.2(1), 86.5(1)°, and interligand N-Zn-S, 125.0(2), 124 4(1)°.