Syntheses, Crystal Structures And Characterizations Of Hexacyanometallate-Based Lanthanide Complexes

Hexacyanometallate-based lanthanide complexes have attracted much more attention for their wide applications in the fields of magnetism, catalysis and luminescent material. The synthesis of new complexes and the study of their properties are of important significance to design novel functional materials and expand their fields of application.In this paper, eleven new hexacyanometallate-based lanthanide complexes: La(phen)3(H2O)[Cr(CN)6]·7H2O (1), Ce(phen)3(H2O)[Cr(CN)6]·7H2O (2), Pr(phen)3(H2O)[Cr(CN)6]·7H2O (3), Nd(phen)3(H2O)[Cr(CN)6]·7H2O (4), Tb(phen)2(H2O)2[Co(CN)6]·9H2O (5), Er(phen)2(H2O)2Fe(CN)6·10H2O (6), Ho(phen)2(H2O)2[Co(CN)6]·8H2O (7), Er(phen)2(H2O)2[Co(CN)6]·8H2O (8), [Tb2(phen)4(H2O)3(OH)Cr(CN)6]NO3·8H2O (9), Nd(H2O)3Co(CN)6·2H2O (10), (Hphen)3Fe(CN)6·CH3CH2OH·3H2O (11), have been prepared and characterized structurally using phen ligand, Ln3+ (Ln = La, Ce, Pr, Nd, Tb, Er, Ho, Eu), and hexacyanometallates [M(CN)6]3- (M = Fe, Cr, Co). Furthermore, powder samples (1a-6a) of 1-6 have been characterized by powder X-ray diffraction (powder XRD), infared spectra (IR), energy dispersive spectra (EDS) and thermogravitry (TG).Single-crystal diffraction analysis reveals that complexes 1-4 are isomorphism. In the structure of 1-4, Ln (Ln = La, Ce, Pr, Nd) and Cr atoms display three-capped triangular prism and octahedral, respectively, while Ln (Ln = Tb, Er) and M (M = Fe, Co) exhibit square-antiprism and octahedral in 5-8. In the structure of 1-6, Ln and M centres are bridged by cyanide groups to form a one-dimensional (1D) chain, which are further linked through hydrogen-bonding,π-πpacking, and Van der Waals interactions, resulting in a three-dimensional supramilecular networks. Power XRD analysis revealed that powder samples (1a-4a) of 1-4 can be obtained by solution mixed method. IR analysis showed the presence of cyanide groups, phen and water molecules in the structure of 1a-4a. EDS results revealed the mole ratio of lanthanide and transition metals is ca.1:1. TG analysis demonstrated that the first weight loss can be attributed to the loss of lattice and coordinated water molecules in the structure. The formula of powder samples for 1a-4a are La(phen)3(H2O)Cr(CN)6·9H2O (1a) , Ce(phen)3(H2O)Cr(CN)6·8H2O (2a) ,Pr(phen)3(H2O)Cr(CN)6·8H2O (3a) and Nd(phen)3(H2O)Cr(CN)6·7H2O (4a), respectively.For heterodimetallic trinuclear cyanide-bridged complex 9, Tb and Cr atoms displayed square-antiprism and octahedral, respectively. Anionic and cationic units are bridged by μ2-OH, resulting in the formation of trinuclear cationic cluster, which are further linked through hydrogen-bonding,π-πpacking, and Van der Waals interactions, resulting in a three-dimensional supramilecular networks. Powder XRD revealed that powder samples (9a) of 9 can not be obtained by solution mixed method.For three-dimensional (3D) hexacyanometallate-based complex 10, Nd and Co atoms exhibited three-capped triangular prism and octahedral. Nd and Co centres are linked by cyanide groups to forming a 3D framework. Powder XRD revealed that powder samples (10a) of 10 can not be obtained by solution mixed method.For mononuclear hexacyanometallate-based complex 11, Fe atom displayed an octahedral geometry. Anionic and cationic units are linked through hydrogen-bonding,π-πpacking, and Van der Waals interactions, resulting in a three-dimensional supramolecular networks. Lanthanide contraction has made an impact on the coordination environment of Ln centres in 1-8. In addition, synthesis conditions and the types of [M(CN)6]3- also lead to the diference in the structure.