Structural Trends in 3 d–4 f Systems. Part II: Ln(NO₃)₃‐Cu(NO₃)₂‐2,2‐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(NO 3 ) 2 , Ln(NO 3 ) 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(NO 3 ) 5 (OH 2 )]; Type-II, [Cu(bpy) 3 ][Ln-(NO 3 ) 5 (OH 2 )] ⋅ 2CH 3 CN (Ln = Ce, Pr); Type-IIa, [Cu(5,5dmbpy) 3 ][Ln(NO 3 ) 5 (OH 2 )] ⋅ 2CH 3 CN (Ln = La, Ce); Type-III, [Cu-(bpy) 3 ][Ln(NO 3 ) 5 ] (Ln = Nd, Sm-Lu); Type-IIIa [Cu(5,5dmbpy) 3 ][Ln(NO 3 ) 5 ] (Ln = Pr, Nd, Sm-Lu); Type-IV, [Cu(5,5dmbpy) 2 (NO 3 )] 2 [Ln(NO 3 ) 5 (OH 2 )]⋅CH 3 CN [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) 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 six types of compounds.