Studies of two lanthanide coordination polymers built up from dinuclear units

Abstract The two three-dimensional oxo-bridged lanthanides {[Ln 2 (C 4 H 2 O 4 ) 3 (H 2 O) 4 ]·3H 2 O} 3 ∞ , with Ln=Ho 3+ ( 1 ); Gd 3+ ( 2 ), are isomorphous. They have layer-type structures built up from non-centrosymmetric dinuclear unit Ln 2 O 12 (H 2 O) 4 , beside three lattice H 2 O molecules stabilizing the 3D open-framework. The building entities are linked through one classical syn-anti μ 2 -carboxylato-K 1 O:K 1 O' bridge. Within the bi-polyhedra, two double μ 2 -O'; μ 2 O';,K 2 O,O' bridges and a syn-syn classical one, support the magnetic measurements carried out on holmium compound indicating relatively weak anti-ferromagnetic interactions. The comparison with magnetic studies on the almost similar reported Gd(III) compound, suggested that concomitant antiferromagnetic and ferromagnetic properties could not be excluded. The two distinct thermal behaviors evidenced the higher metal-water bond strength with the smaller cation, and revealed the great supramolecular effects generated by hydrogen-bonding patterns.