Structural Trends in a 3 d-4 f System: Ln(NO < inf > 3 < /inf > ) < inf > 3 < /inf > −Cu(2,2-bipyridine) < inf > 2 < /inf > (NO < inf > 3 < /inf > ) < inf > 2 < /inf > (Ln=La−Nd, Sm−Yb)

Abstract

A series of thirteen complexes which may be formally considered as assembled from Cu(bpy) 2 (NO 3 ) 2 and Ln(NO 3 ) 3 (Ln=La−Yb excluding Pm, bpy=2,2’-bipyridine) have been characterized. The crystals may be grouped into four classes: A, [Cu 2 (bpy) 4 (μ-NO 3 )][Ln(NO 3 ) 6 ] (Ln=La−Nd); B, [Cu(bpy) 2 (NO 3 )] 2 [Ln(NO 3 ) 4 (OH 2 ) 2 ](NO 3 ) (Ln=Sm−Dy); C, [Cu(bpy) 2 (NO 3 )] 2 [Ln(NO 3 ) 5 ] (Ln=Ho−Tm); D, [Cu(bpy) 2 (NO 3 )] 2 [Ln(NO 3 ) 3 (OH 2 ) 3 ](NO 3 ) 2 ⋅2H 2 O (Ln=Yb). The coordination numbers of the nitrato or aquonitrato lanthanide anions range from 9 to 12. The dinuclear cation in Class A having a linear monoatomic nitrate bridge is new and is seen to produce weak antiferromagnetic coupling in these compounds. The other classes contain distortion isomers of [Cu(bpy) 2 NO 3 ] + . The structural trends are analysed in terms of lanthanide contraction and non-covalent interactions in the crystals. EPR and electronic spectral characteristics are discussed for the four classes of compounds.