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.