Effects of lanthanide metal size and aminoligand denticity on the solvothermal systems Ln/Sn/Se/en and Ln/Sn/Se/dien (Ln = lanthanide)

Abstract

Two systems, Ln/Sn/Se/en and Ln/Sn/Se/dien, were investigated under solvothermal conditions, and novel lanthanide selenidostannates [{Ce(en)₄}₂(μ-Se₂)]Sn₂Se₆ (1a), [{Ln(en)₃}₂(μ-OH)₂]Sn₂Se₆ (Ln = Pr(1b), Nd(1c), Gd(1d); en = ethylenediamine), [{Ln(dien)₂}₄(μ₄-Sn₂Se₉)(μ-Sn₂Se₆)]_∞ (Ln = Ce(2a), Nd(2b)), and [Hdien][Gd(dien)₂(μ-SnSe₄)] (2c) (dien = diethylenetriamine) were prepared and characterized. Two structural types of lanthanide selenidostannates were obtained across the lanthanide series in both systems. In the Ln/Sn/Se/en system, two types of binuclear lanthanide complex cations [Ce₂(en)₈(μ-Se₂)]⁴⁺ and [{Ln(en)₃}₂(μ-OH)₂]⁴⁺ (Ln = Pr, Nd, Gd) were formed depending on the Ln³⁺ ions. The complex cations are compensated by the [Sn₂Se₆]⁴⁻ anions. In the Ln/Sn/Se/dien system, coordination polymer [{Ln(dien)₂}₄(μ₄-Sn₂Se₉)(μ-Sn₂Se₆)]_∞ and ionic complex [Hdien][Gd(dien)₂(μ-SnSe₄)] are obtained along the lanthanide series, among which the μ₄-Sn₂Se₉, μ-Sn₂Se₆ and μ-SnSe₄ ligands to the Ln³⁺ ions were observed. The formation of title complexes shows the effects of lanthanide metal size and amino ligand denticity on the lanthanide selenidostannates. Complexes 1a-2c exhibit semiconducting properties with band gaps between 2.08 and 2.48 eV.