Syntheses, Structures, and Magnetic Properties of a Series of Heterotri-, Tetra- and Pentanuclear Ln III ⁻Co II Compounds.

Three types of Ln(III)⁻Co(II) heterometallic compounds, LnCo₂(L1)₇(bipy)₂ (Ln = Pr- 1 , Eu- 2 , Sm- 3 , Gd- 4 , Tb- 5 , Dy- 6 ) (L1 = 4-chlorobenzoate, bipy = 2,2'-bipyridine), Ln₂Co₂(L₂) ₁₀ (bipy)₂ (Ln = Sm- 7 , Gd- 8 , Tb- 9 , Dy- 10 , Ho- 11 , Er- 12 , Yb- 13 ), (L2 = 2,4-dichlorobenzoate, bipy = 2,2'-bipyridine, phen = 1,10-phenanthroline), and Ln₂Co₃(L1) ₁₂ (bipy)₂ (Ln = Ho- 14 , Er- 15 , Yb- 16 ), were synthesized under hydrothermal conditions and characterized by single crystal X-ray diffraction, IR spectroscopy and magnetic measurements. Structural analyses revealed that 14 ⁻ 16 take on a unique linear pentanuclear structural motif. Interestingly, the Ho-containing compound 14 exhibits magnetic relaxation behavior.