New Cu(I)-Ethylene Complexes Based on Tridentate Imine Ligands: Synthesis and Structure

A new bulky facially coordinating N₃-donor tach-based ligand (tach: cis,cis-1,3,5-triaminocyclohexane) [1: cis,cis-1,3,5-tris­(2-fluoro-6-(trifluoromethyl)­benzylideneamino)­cyclohexane] has been obtained from the condensation of tach with 3 equiv of the appropriate benzaldehyde. Reaction of 1 with [Cu­(NCMe)₄]­[PF₆] gave the complex [(1)­Cu­(NCMe)]­[PF₆]. Displacement of the acetonitrile ligand is possible with CO and C₂H₄ (3–5 bar). Cu­(I)-ethylene complexes of ligands 1 and 2 [2: cis,cis-1,3,5-(mesitylideneamino)­cyclohexane] were prepared successfully by treatment of the ligands with CuBr and AgSbF₆ in the presence of ethylene. These complexes display reversible complexation of the ethylene molecule under mild changes to pressure, suggesting possible application in olefin separation and extraction.