Synthesis and characterization of [Pb{Se2P(OiPr)2}2]n pseudo polymorphs: Polymeric, single source precursor enabling preparation of shape-controlled lead selenide structures

Abstract

Novel lead pseudo polymorphs supported by diselenophosphate (dsep) ligands, [Pb{Se₂P(OⁱPr)₂}₂]_n (1α and 1β), were synthesized and structurally characterized. The two structures differed in the binding modes of the dsep ligand. Each repeating unit in 1α was composed of a lead atom coordinated by two dsep ligands, one in a chelating mode and the other in a bridging–dangling mode. By contrast, the dsep ligands in 1β adopted a bimetallic-biconnective (μ₁-S, μ₁-S) binding pattern. The bridging–dangling mode observed in 1α is the first example of this mode for the dsep ligand. [Pb{Se₂P(OⁱPr)₂}₂]_n could be successfully utilized as a single source precursor (SSP) for growing lead selenide (PbSe) nanostructures with different shapes via the solvothermal process. The morphologies of the as-grown PbSe structures were controlled by capping agents, poly(vinyl pyrrolidone) (PVP) and ethylenediamine, both bind on the {200} plane and enhance the growth rate of the <111> direction of the PbSe crystals, resulting in the formation of cubes and eight-horned rod dendrites, respectively. Raman spectroscopy was utilized to investigate the phonon vibration behaviour of the as-grown eight-horned rod dendrites. All peaks in the Raman spectra can be attributed to longitudinal (LO) and transverse (TO) optical phonon modes of the PbSe rod dendrites.