Static field induced magnetic relaxations in dinuclear lanthanide compounds of [phen2Ln2(HCOO)4(HCOO)2-2x (NO3)2x ] (1, Ln = Gd and x=0.52; 2, Ln = Er and x=0.90; phen=1,10-phenanthroline)

Two dinuclear lanthanide (Ln) complexes, formulated as [phen(2)Ln(2)(HCOO)(4)(HCOO)(2-2x) (NO3)(2x) ] (1, Ln = Gd and x = 0.52; 2, Ln = Er and x = 0.90; phen = 1,10-phenanthroline), were synthesized and characterized. They are isostructural. The dinuclear molecule consists of two Ln(3+) bridged by four formate groups and chelated by phen and formate/nitrate ligands, and the Ln(3+) possesses a coordination environment of distorted tri-capped trigonal prism of LnO(7)N(2). Both compounds behave as paramagnets between 2 and 300 K, but display two static field induced magnetic relaxation processes. One is slow and of spin-lattice type, and it results from the lifting of Kramer's degeneracy of the ground-states of both Gd3+ and Er3+, and the other is fast, and it might be spin-spin type.