Crystal structures and spectroscopic properties of the polymeric adducts formed from Cu(CN) and Cu(NCS) with 2,9-dimethyl-1,10-phenanthroline

Abstract

The crystal structures of the title adducts, [{Cu(dmphen)(CN)}_n](1) and [{Cu(dmphen)(NCS)}_n](2)(dmphen = 2, 9-dimethyl-1,10-phenanthroline), consist of one-dimensional zigzag chains of tetrahedral copper(I) atoms linked by cyanide and thiocyanate groups, respectively. Stacks of dmphen molecules are formed by the ‘fitting’ of centrosymmetrical polymeric sequences. Complex (1) crystallizes in space group P2₁/n with cell dimensions, a= 9.839(4), b= 7.788(2), c= 16.559(7)Å, β= 92.33(4)°, and Z= 4; (2) crystallizes in space group Pbca, with cell dimensions, a= 16.283(3), b= 9.485(2), c= 18.115(3)Å, and Z= 8. Polarization properties of the i.r. and electronic bands have been determined. Chain formation affects the vibration and bending modes within the zigzag system. In the optical spectrum of both the complexes two bands have been detected : one charge-transfer from d_yz of copper to φ₉(lowest unoccupied molecular orbital of dmphen), polarized along the short axis (z) of each [Cu(dmphen)]⁺ mono-complex, and another from d_z² or d_x²–y² of copper to φ₉, plane-polarized (xy) because of some vibronic or electronic coupling mechanism operating between the above mentioned mono-complexes stacked in the ‘fitted’ polymeric sequences.