Bimetallic Trifluoroacetates as Single-Source Precursors for Alkali–Manganese Fluoroperovskites

Abstract

Alkali-manganese(II) trifluoroacetates were synthesized, and their potential as single-source precursors for the solid-state and solution-phase synthesis of AMnF fluoroperovskites (A = Na, K, Rb, Cs) was demonstrated. Crystals of NaMn(tfa)(tfaH), KMn(tfa)(tfaH)·HO, RbMn(tfa)·HO, and CsMn(tfa) (tfa = trifluoroacetato) were grown via solvent evaporation and their crystal structures solved using single-crystal X-ray diffraction (XRD). Chemical purity was confirmed using thermal analyses (TGA/DTA) and Rietveld analysis of powder XRD patterns. Thermal decomposition of NaMn(tfa)(tfaH), KMn(tfa)(tfaH)·HO, RbMn(tfa)·HO, and CsMn(tfa) in both the solid state and solution phase yielded crystalline, single-phase NaMnF, KMnF, RbMnF, and CsMnF fluoroperovskites, respectively. Nanocrystals (<100 nm) and submicrocrystals (<500 nm) were obtained in a mixture of high-boiling-point organic solvents. Crystal structures of bimetallic trifluoroacetates displayed a variety of building blocks, coordination environments of the alkali atoms, and coordination modes of the trifluoroacetato ligand. Alkali-fluorine interactions ranging from chemical bonds to short contacts were observed throughout the series. The coordination flexibility of the trifluoroacetato ligand was attributed to the ability of the -CF groups to interact with alkali atoms over a broad range of distances. The synthetic approach described in this investigation provides a starting point to expand the library of fluorinated single-source precursors suitable for solution-phase routes to mixed-metal fluorides.

Coinage metal aluminyl complexes: probing regiochemistry and mechanism in the insertion and reduction of carbon dioxide

“…4 Such systems also offer potential as single source precursors for metal alloys and functional materials. [5][6][7][8] Of particular interest are binuclear systems featuring elements from group 13 (Chart 1). The presence of a strongly Lewis acidic centre in close proximity to a d-block metal can assist in substrate activation, and has proven effective, for example, in mixed transition metal/aluminium systems for alkene polymerisation.…”

Intermetallic Nanocatalysts from Heterobimetallic Group 10–14 Pyridine-2-thiolate Precursors

“…61 Rather than starting with two separate metallic precursors and reducing them together, this approach uses premade complexes where two metals are already present and bonded together. 62,63,64,65,66,67,68 In this work, we study the solid-state decomposition of a family of group 10-14 heterobimetallic complexes as precursors to the preparation of 10-14 intermetallic compounds. Our approach is related to the use of single-source precursors (SSPs), which are commonly employed in chemical vapor deposition in order to lower decomposition temperatures and prevent phase segregation.…”

Building Fluorinated Hybrid Crystals: Understanding the Role of Noncovalent Interactions

“…Metal-fluorine contacts present in these crystals provide a low-temperature pathway for their decomposition into the corresponding mixed-metal fluorides or oxifluorides, thereby making fluorinated hybrid crystals ideal single-source precursors for solution-phase routes to compositionally complex functional materials. 4,[11][12][13][14] One of the main challenges facing the design and predictive synthesis of fluorinated hybrid crystals is the lack of quantitative understanding of the role of metal-fluorine noncovalent interactions in determining their crystal-chemistry. Of particular importance is the understanding of the electronic and steric effects of these interactions on metal connectivity and coordination, which ultimately dictate crystal cohesion.…”

“…, and CsMn(tfa) 3 (tfa = trifluoroacetato; tfaH = trifluoroacetic acid) have recently been shown to serve as single-source precursors for solution-phase routes to the corresponding mixed-metal fluorides; 14 their crystal structures are shown in Figure 1. Using the NCI approach, we establish the nature, strength, and compositional dependence of the four noncovalent interactions present in these hybrid crystals.…”

“…The relative errors for lattice constants (Δ) and the average relative error for Mn/K-O/F distances (Δ d ) were computed using experimental crystallographic data as reference. 14 The revPBE-D2 approach provided the most accurate description of the K 2 Mn 2 (tfa) 6 (tfaH) 2 •H 2 O structure. A maximum error of 0.21% was obtained for lattice constants, and average errors in the 0.46-1.32% range were determined for interatomic distances.…”