Cu(I) complexes based on cis, cis-1,3,5-tris(arylideneamino)cyclohexane ligands: synthesis, structure and CO binding

A new series of sterically bulky, facially coordinating N-3-donor tach-based ligands (tach; cis, cis-1,3,5-triaminocyclohexane) [2.1; cis, cis-1,3,5-tris(2,4-dimethylbenzylideneamino)cyclohexane, 4.1; cis, cis-1,3,5-tris(pentamethylbenzylideneamino)cyclohexane, 5.1; cis, cis-1,3,5-tris(2,6dimethoxybenzylideneamino)cyclohexane, 6.1; cis, cis-1,3,5-tris(pentafluorobenzylideneamino)cyclohexane, 7.1; cis, cis-1,3,5-tris(3,5-bis(ditrifluoromethyl)benzylideneamino)cyclohexane, 8.1; cis, cis-1,3,5-tris(2-trifluoromethylbenzylideneamino)cyclohexane, 9.1; cis, cis-1,3,5-tris(2-methoxybenzylideneamino)cyclohexane] have been obtained from the condensation of tach with three equivalents of the appropriate substituted benzaldehyde. Reaction with [Cu(NCCH3)(4)]PF6 gives Cu(I) complexes of tach-based ligands {2.2-9.2, eg; 2.2; [Cu(2.1)(NCCH3)]PF6}. Displacement of the acetonitrile ligand by CO was achieved successfully for all the Cu(I) complexes of tach-based ligands and the resulting complexes have been shown to bind carbon monoxide {2.3-9.3, eg; 2.3; [Cu(2.1)(CO)]PF6}. The X-ray single crystal structures of 5.1, 8.1, 9.1, 3.2, 7.2, 8.2, 9.2, 3.3, 5.3 and 6.3 have been determined.