A series of new lanthanoid thioarsenates: insights into the influence of lanthanide contraction on the formation of new lanthanoid thioarsenates.

A series of new lanthanoid thioarsenates [Ln(teta)(μ-η(1):η(2):η(1)-As(III)S3)]n {Ln = Ce (Ia), Pr (Ib), Nd (Ic), and Sm (Id); teta = triethylenetetramine} and [Ln(teta)(en)(μ-η(1):η(1):η(1)-As(V)S4)]n {Ln = La (IIa), Ce (IIb), Pr (IIc), and Nd (IId); en = ethylenediamine} were prepared by the solvothermal reaction of K3AsO3, S, LnCl3 and organic amines and structurally characterized. Compounds Ia–d crystallise in the orthorhombic space group Aba2 and display 1-D neutral chains [Ln(teta)(μ-η(1):η(2):η(1)-As(III)S3)]n, which represent the first examples of 1-D organic hybrid lanthanoid sulfides built up from trigonal-pyramidal As(III)S3 acting as tetradentate bridging ligands to interlink Ln(teta) ions, while compounds IIa–d crystallise in the orthorhombic space group P2(1)2(1)2(1) and consist of other 1-D neutral chains [Ln(teta)(en)(μ-η(1):η(1):η(1)-As(V)S4)]n, which are built up from the linkages of the tetrahedral As(V)S4 ion and the Ln(teta)(en) ion. To learn more about the influence of lanthanide contraction on the formation of lanthanoid thioarsenates, three organic hybrid lanthanoid thioarsenates [Ln(teta)(en)As(V)S4] [Ln = Dy (IIIa), Ho (IIIb), and Tm (IIIc)] with the neutral molecular structure type in the monoclinic centrosymmetric space group P2(1)/c are also presented. Their optical and magnetic properties have been investigated, and density functional theory calculations of Ia and IIa have also been performed.