X-Ray structural and gas phase studies of silver(i) perfluorinated carboxylate complexes with 2,2′-bipyridyl as potential precursors for chemical vapour deposition (CVD)

Abstract

[Ag(CF₃COO)(bpy)] (1), [Ag₂(C₂F₅COO)₂(bpy)] (2) and [Ag₂(C₃F₇COO)₂(bpy)] (3) were prepared and characterized by MS-EI, ¹H, ¹³C NMR, variable-temperature IR (VT-IR) spectroscopy (solid sample and evolved volatile species) and thermal analysis. Single-crystal X-ray diffraction data revealed the polymeric structure for [Ag₂(C₂F₅COO)₂(bpy)] and [Ag₆(C₃F₇COO)₆(bpy)₄], with bridging bpy ligand, whereas for [Ag(CF₃COO)(bpy)] the dimeric system with monodentately linked carboxylate was noted. Mass spectra analysis of (1–3) over 30–300 °C indicates the presence of binuclear ions [(RCOO)Ag₂]⁺ as a main volatile particles, which can be transported in CVD process. VT-IR studies of gases evolved during the thermal decomposition process, demonstrate the presence of fluorocarbon species and CO₂ as the most abundant molecules. Thermal analysis of (1–3) revealed a multi-stage decomposition mechanism resulting in Ag⁰ formation below 290 °C. Compounds were tested for silver metal spray pyrolysis and obtained layers were characterized by scanning electron microscopy (SEM-EDX) and XRD.