Syntheses and coordination isomerism of heteroleptic divalent-metal (M = Co, Zn) carbazate complexes

Abstract

Three heteroleptic divalent-metal alkyl-carbazate-thiocyanate complexes, [M(NCS)₂(NH₂NHCOOR)₂] [M = Co and R = CH₂CH₃ (1); M = Co and R = CH₃ (2); M = Zn and R = CH₃ (3)], have been prepared and characterized, and their crystal structures determined. In 1, Co(II) adopts a fairly regular centrosymmetric trans-CoO₂N₄ octahedral geometry arising from its coordination by two N,O-bidentate ethylcarbazate ligands and two trans N-bonded thiocyanates. In isostructural 2 and 3, the metals adopt distorted cis-MO₂N₄ octahedral geometries arising from two N,O-bidentate methylcarbazate ligands with cis N-bonded thiocyanates. The crystal structures feature N–H⋯O and N–H⋯S interactions. Thermal analysis data show that these compounds begin to decompose at temperatures between 130 and 160 °C. Crystal data: 1, CoC₈H₁₆N₆O₄S₂, M_r = 383.32, P2₁/n (No. 14), a = 5.2599(3) Å, b = 7.4209(4) Å, c = 20.1948(12) Å, β = 94.070(1)°, V = 786.28(8) ų, Z = 2, R(F) = 0.028, wR(F²) = 0.073; 2, CoC₆H₁₂N₆O₄S₂, M_r = 355.27, P2₁/n (No. 14), a = 7.8663(3) Å, b = 10.5804(3) Å, c = 17.6313(5) Å, β = 102.019(10)°, V = 1435.26(8) ų, Z = 4, R(F) = 0.036, wR(F²) = 0.097; 3, ZnC₆H₁₂N₆O₄S₂, M_r = 361.71, P2₁/n (No. 14), a = 7.8883(2) Å, b = 10.5756(3) Å, c = 17.5827(5) Å, β = 101.676(1)°, V = 1436.46(7) ų, Z = 4, R(F) = 0.031, wR(F²) = 0.084.

Graphical Abstract

Keywords:

• Coordination isomerism
• Thiocyanate anion
• Bidentate ligand
• Crystal structure