Abstract
The reaction of hydrated salts of paramagnetic lanthanides (GdCl(3), DyCl(3), and HoCl(3)) with sterically hindered phosphinic acid (trityl-H-phosphinic acid) in a stoichiometric ratio of 1:2 afforded dinuclear gadolinium {Gd(2)[Ph(3)C-(H)-(PO(2))](4)(CH(3)OH)(8)}-(CH(3)OH)(8)Cl(2) (1), isostructural paddlewheel-type trinuclear dysprosium {Dy(3)[(Ph(3)C)-(H)-(PO(2))](8)(H(2)O)(6)} (2), and holmium {Ho(3)[(Ph(3)C)-(H)-(PO(2))](8)(DMF)(4)(H(2)O)(2)} (3) complexes. The direct current (dc) magnetic measurements indicate potentially very weak magnetic interactions at low temperatures for all complexes (1-3). Alternating current (ac) magnetic susceptibility measurements show field-induced out-of-phase magnetic susceptibility signals for the isotropic Gd(III) complex (1). Slow magnetic relaxation in this case is attributed to either a direct process or a phonon bottleneck effect. The Dy(III) complex (2) also exhibits the single-molecule magnet behavior under an applied magnetic field of 2200 Oe, with slow magnetic relaxation occurring through a combination of Raman and Orbach processes, while the small n exponent value also suggests the participation of the phonon bottleneck effect. Additionally, detailed theoretical studies are provided to explain and understand the observed magnetic properties of these complexes.