Synthesis, characterization and reactivity of a trinuclear copper(II) thiocyanurate complex: A spin-frustrated molecular propeller

1,3-bis{2-(4-methylpyridyl)imino}isoindoline (4-MeInH) reacts with copper(II) acetate and 2,4,6-trimercaptotriazine (H3TMTA) to yield [Cu(4-MeIn)]3(TMTA), a trinuclear propeller complex composed of three Cu(4-MeIn) “blades” coordinated to a 2,4,6-trimercaptotriazine (TMTA) “hub”. Each copper(II) center is coordinated via a exocyclic sulfur and a ring nitrogen from TMTA. Although the trimer is infinitely stable in the solid state, dark green solutions fade over time to produce a mixture of dinuclear products which are a result of both hydrolysis and desulfurization reactions. Variable temperature magnetic susceptibility measurements on [Cu(4-MeIn)]3(TMTA) are consistent with a spin-frustrated doublet ground state and show the presence of moderate antiferromagnetic coupling (−2J = 38.14 cm−1) between the copper(II) centers.

Graphical abstract[Cu(4-MeIn)]3(TMTA), a trinuclear propeller complex composed of three Cu(4-MeIn) “blades” coordinated to a 2,4,6-trimercaptotriazine (TMTA) “hub”. The complex exhibits moderate antiferromagnetic interactions and is a classic example of a spin-frustrated molecule. After extended periods of time in solution, the complex yields dinuclear products which are a result of desulfurization reaction.Figure optionsDownload full-size imageDownload as PowerPoint slide