Two mixed-ligand lanthanide-hydrazone complexes: [Pr(NCS)3(pbh)2]·H2O and [Nd(NCS)(NO3)(pbh)2(H2O)]NO3·2.33H2O [pbh is N'-(pyridin-2-ylmethylidene)benzo-hydrazide, C13H11N3O].

The gel-mediated syntheses and crystal structures of [N'-(pyridin-2-ylmethylidene-κN)benzohydrazide-κ(2) N',O]tris(thiocyanato-κN)praseodymium(III) mono-hydrate, [Pr(NCS)3(C13H11N3O)2]·H2O, (I), and aqua(nitrato-κ(2) O,O')[N'-(pyri-din-2-ylmethylidene-κN)benzohydrazide-κ(2) N',O](thiocyanato-κN)neo-dym-ium(III) nitrate 2.33-hydrate, [Nd(NCS)(NO3)(C13H11N3O)2(H2O)]NO3·2.33H2O, (II), are reported. The Pr(3+) ion in (I) is coordinated by two N,N,O-tridentate N'-(pyridin-2-ylmethylidene)benzohydrazide (pbh) ligands and three N-bonded thio-cyanate ions to generate an irregular PrN7O2 coordination polyhedron. The Nd(3+) ion in (II) is coordinated by two N,N,O-tridentate pbh ligands, an N-bonded thio-cyanate ion, a bidentate nitrate ion and a water mol-ecule to generate a distorted NdN5O5 bicapped square anti-prism. The crystal structures of (I) and (II) feature numerous hydrogen bonds, which lead to the formation of three-dimensional networks in each case.