Structural Trends in 3 d–4 f Systems. Part II: Ln(NO < inf > 3 < /inf > ) < inf > 3 < /inf > -Cu(NO < inf > 3 < /inf > ) < inf > 2 < /inf > -2,2-biyridine/5,5-dimethyl-2,2-bipyridine (Ln=La-Nd, Sm-Lu)

Abstract

A series of thirty six complexes obtained from acetonitrile solutions of Cu(NO3)2, Ln(NO3)3 and 2,2-biyridine or 5,5-dimethyl-2,2-bipyridine (Ln=La-Yb excluding Pm) have been characterized. The crystals may be grouped into six types: Type-I, [Cu(bpy)3][La(NO3)5(OH2)]; Type-II, [Cu(bpy)3][Ln(NO3)5(OH2)] ⋅ 2CH3CN (Ln=Ce, Pr); Type-IIa, [Cu(5,5-dmbpy)3][Ln(NO3)5(OH2)] ⋅ 2CH3CN (Ln=La, Ce); Type-III, [Cu(bpy)3][Ln(NO3)5] (Ln=Nd, Sm–Lu); Type-IIIa [Cu(5,5-dmbpy)3][Ln(NO3)5] (Ln=Pr, Nd, Sm-Lu); Type-IV, [Cu(5,5-dmbpy)2(NO3)]2[Ln(NO3)5(OH2)]⋅CH3CN [Ln=La-Nd, Sm-Tb). The coordination numbers of the nitrato and aquonitrato lanthanide anions are 10 and 11, respectively. The tris-chelates in Types I, II and IIIa undergo static Jahn-Teller distortion while Types IIa and III support fluxional tris-chelate ions. Type-IV contains distortion isomers of [Cu(5,5-dmbpy)2NO3]+. 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 six types of compounds.