The Flight of the Monarch: [Cu(L)(CH3CN)(PPh3)]ClO4 (L = 2,5-Diphenyl-3,4-bis(2-pyridyl) Cyclopenta-2,4-dien-1-one)

The mononuclear complex [Cu(L)(CH3CN)(PPh3)]ClO4, (1), (L= 2,5-diphenyl-3,4-bis(2-pyridyl)cyclopenta-2,4-dien-1-one), has been synthesized and investigated by elemental analysis, IR, 1H NMR, UV-Vis spectroscopic methods and X-ray diffraction. The complex crystallizes in the non-centrosymmetric space group P212121 in accord with the asymmetric (atropisomer) Cu centre. Its coordination polyhedron has four vertices and is devoid of any symmetry. The [Cu(L)(CH3CN)(PPh3)]ClO4 is amongst the few MeL complexes crystallizing in a non-centrosymmetric space group. The bite-angle of the bidentate ligand L is 90.92(13)°, indicating some strain in the structure; this entails an enhanced instability of the complex with respect to strongly coordinating solvents. The crystal of 1 owes its cohesion to a multitude of weak C-H...O and C-H... interations. The electrochemistry of the complex shows three reversible ligand-centred reduction processes and an irreversible metal-centred one. This indicates that the coordination of the CuI(CH3CN)(PPh3) moiety to the L leads to the delocalization of electron density from L to the CuI(CH3CN)(PPh3) moiety.