Heterometallic Molecular and Ionic Isomers.

Numerous descriptions of structural isomerism in metal complexes do not list any molecular vs ionic isomers. At the same time, one of the most striking examples of structural isomerism in organic chemistry is molecular urea, which has the same atomic composition as the chemically distinct ionic ammonium cyanate. This iconic organic couple now meets its inorganic heterometallic counterpart.

Two polymorph modifications of tris(hexafluoroacetylacetonato)iron(III) revealed: is that common for other trivalent metals?

A long-standing issue about the correct identification of an important starting reagent, iron(III) hexafluoroacetylacetonate, Fe(hfac) (1), has been resolved. The tris-chelated mononuclear complex was found to crystallize in two polymorph modifications which can be assigned as the low-temperature (1-L) monoclinic P2/n and the high-temperature (1-H) trigonal P-3. Low-temperature polymorph 1-L was found to transform to 1-H upon sublimation at 44 °C.

From cubane-assembled Mn-oxo clusters to monodispersed manganese oxide colloidal nanocrystals.

The assemblies of [MO] (M = metal) cubanes represent a fascinating class of materials for a variety of application fields. Although such a structural characteristic is relatively common in small molecules and in extended bulk solids, high nuclearity clusters composed of multiple [MO] units as their backbones are rare. In this work, we report two new Mn-oxo clusters, Mn Mn O(OOCMe)(OMe)(py) ([Mn-Ac]) and Mn Mn O(OOCCMe)(OMe)(MeOH)(py) ([Mn-Piv]), whose core structures are assemblies of either 6- or 7-cubanes in different packing patterns, which have been unambiguously revealed by single crystal X-ray diffraction technique.

Trickier than It Looks: Isomerization between Five- and Six-Coordinated Zinc in Heterometallic LiZn Molecule.

This report describes the synthesis and characterization of two heterometallic Li-Zn coordination isomers [LiZn(tbaoac)] (tbaoac = -butyl acetoacetato) that have been isolated separately by the same stoichiometric reaction run in different organic solvents. The 6-coordinated zinc isomer () was synthesized in acetone with high yield, while the 5-coordinated one () was readily obtained from ethanol. The isomer has a low solubility in organic solvents such as alkanes and haloalkanes, while its counterpart exhibits a good solubility in almost all common solvents.

Synthesis, Structure, and Characterizations of a Volatile/Soluble Heterometallic Hexanuclear Precursor [NaMn(thd)(OAc)].

The paper describes a heterometallic mixed-ligand hexanuclear precursor [NaMn(thd)(OAc)] () (thd = 2,2,6,6-tetramethyl-3,5-heptadionate; OAc = acetate) that was designed based on its lithium homoleptic analogue, [LiMn(thd)], by replacing one of the thd ligands with an acetate group in order to accommodate 5-coordinated sodium instead of tetrahedral lithium ion. The complex, which is highly volatile and soluble in a variety of common solvents, has been synthesized by both the solid-state and solution methods. The unique "dimer-of-trimers" heterometallic structure consists of two trinuclear [NaMn(thd)] units firmly bridged by two acetate ligands.

Multi-functional Single-Source Molecular Precursors for Carbon-Coated Mixed-Metal Phosphates.

We introduce a new synthetic concept that can be broadly adopted for the low-temperature preparation of mixed-metal energy storage materials, such as phosphates, silicates, fluorides, fluorophosphates, and fluorosulfates that exhibit intrinsic low electronic conductivity and thus require a carbon modulation. The development of novel low-temperature approaches for assembling energy-related materials with a complex core-shell microstructure is of great importance for expanding their application scope. The traditional definition of single-source precursors refers to their ability to yield a phase-pure material upon thermal decomposition.

Intermetallic Compound ReGaGe with Re- and Ge-Embedded Gallium Clusters: Synthesis, Crystal Structure, Chemical Bonding, and Physical Properties.

Transition metal-based endohedral cluster intermetallic compounds are interesting electron phases, which frequently exhibit superconductivity with a peculiar interplay between the critical temperature and valence electron count. We present a new Re-based endohedral gallium cluster compound, ReGaGe. Its unique crystal structure (4 space group, = 8.

Molecular and Supramolecular Structures of Triiodides and Polyiodobismuthates of Phenylenediammonium and Its N,N-dimethyl Derivative.

Despite remarkable progress in photoconversion efficiency, the toxicity of lead-based hybrid perovskites remains an important issue hindering their applications in consumer optoelectronic devices, such as solar cells, LED displays, and photodetectors. For that reason, lead-free metal halide complexes have attracted great attention as alternative optoelectronic materials. In this work, we demonstrate that reactions of two aromatic diamines with iodine in hydroiodic acid produced phenylenediammonium (PDA) and N,N-dimethyl-phenylenediammonium (DMPDA) triiodides, PDA(I)⋅2HO and DMPDA(I)I, respectively.

Protective Spinel Coating for LiNiMnCoO Cathode for Li-Ion Batteries through Single-Source Precursor Approach.

The LiNiMnCoO Li-rich NMC positive electrode (cathode) for lithium-ion batteries has been coated with nanocrystals of the LiMnCoO high-voltage spinel cathode material. The coating was applied through a single-source precursor approach by a deposition of the molecular precursor LiMnCo(thd) (thd = 2,2,6,6-tetramethyl-3,5-heptanedionate) dissolved in diethyl ether, followed by thermal decomposition at 400 °C inair resulting in a chemically homogeneous cubic spinel. The structure and chemical composition of the coatings, deposited on the model SiO spheres and Li-rich NMC crystallites, were analyzed using powder X-ray diffraction, electron diffraction, high angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), and energy-dispersive X-ray (EDX) mapping.

Electron-Precise Semiconducting ReGaGe: Extending the IrIn Structure Type to Group 7 of the Periodic Table.

Intermetallic compounds with semiconducting properties are rare, but they give rise to advanced materials for energy conversion and saving applications. Here, we present ReGaGe, a new electron-precise narrow-gap intermetallic semiconductor. The compound crystallizes in the IrIn structure type (space group 4/, = 6.

Heterometallic Precursor with 2:2:1 Metal Ratio Requiring at Least a Pentanuclear Molecular Assembly.

This work represents an important step in the quest to make heterometallic molecules featuring specific metal types and complicated metal ratios. The rational design, synthesis, and characterization of a complex heterometallic single-source molecular precursor for the next generation sodium-ion battery cathode material, NaMnFeO, is described. A unique pentametallic platform [Mn(ptac)-Na-Mn(acac)-Na-Mn(ptac)] () was derived from the known polymeric structure of [NaMn(acac)], through a series of elaborate design procedures, such as mixed-ligand, unsymmetric ligand, and mixed-valent approaches.

Assembling Polyiodides and Iodobismuthates Using a Template Effect of a Cyclic Diammonium Cation and Formation of a Low-Gap Hybrid Iodobismuthate with High Thermal Stability.

Exploiting a template effect of 1,4-diazacycloheptane (also known as homopiperazine, Hpipe), four new hybrid iodides, (HpipeH)BiI·2HO, (HpipeH)I(I), (HpipeH)I·HO, and (HpipeH)(HO)I, were prepared and their crystal structures were solved using single crystal X-ray diffraction data. All four solid-state crystal structures feature the HpipeH cation alternating with BiI, I, or I anions and solvent water or HO cation. HpipeH assembles anionic and neutral building blocks into polymer structures by forming four strong (N)H···I and (N)H···O hydrogen bonds per cation, with the H···I distances ranging from 2.

Heterotrimetallic Mixed-Valent Molecular Precursors Containing Periodic Table Neighbors: Assignment of Metal Positions and Oxidation States.

A known trinuclear structure was used to design the heterobimetallic mixed-valent, mixed-ligand molecule [Co (hfac) -Na-Co (acac) ] (1). This was used as a template structure to develop heterotrimetallic molecules [Co (hfac) -Na-Fe (acac) ] (2) and [Ni (hfac) -Na-Co (acac) ] (3) via isovalent site-specific substitution at either of the cobalt positions. Diffraction methods, synchrotron resonant diffraction, and multiple-wavelength anomalous diffraction were applied beyond simple structural investigation to provide an unambiguous assignment of the positions and oxidation states for the periodic table neighbors in the heterometallic assemblies.

Endohedral Cluster Superconductors in the Mo-Ga-Sn System Explored by the Joint Flux Technique.

Endohedral Ga cluster compounds feature nontrivial superconducting states including the two-gap superconductivity similar in nature to MgB. We use the joint flux synthetic technique to introduce Sn into the Ga matrix and tune the valence electron count in the two new endohedral cluster superconductors MoGaSn and MoGaSn with critical temperatures of = 8.7 and 5.

From lithium to sodium: design of heterometallic molecular precursors for the NaMO cathode materials.

Based on the well-established model structure of LiM(tbaoac), the first series of heterometallic molecular precursors NaM(tbaoac)(THF) (M = Fe, Co, and Ni) have been designed and successfully utilized for the preparation of NaMO oxide cathode materials of sodium-ion batteries.

From endohedral cluster superconductors to approximant phases: synthesis, crystal and electronic structure, and physical properties of MoGaZn and MoGaZn.

Using the crystal-growth joint flux technique based on the combination of two aliovalent low-melt metals, gallium and zinc, we adjust the gross valence electron count in the Mo-Ga-Zn system and produce the MoGaZn and MoGaZn intermetallic compounds. Gradual reduction in the valence electron count first leads to the Zn for Ga substitution in the MoGa endohedral cluster superconductor, accompanied by the formation of Zn-containing clusters in the crystal structure and by the gradual suppression of superconductivity. MoGaZn with x = 7.

From a volatile molecular precursor to twin-free single crystals of bismuth.

A highly volatile molecular precursor, dibismuth(ii) (tetra)trifluoroacetate, was successfully utilized for the gas phase growth of twin-free single crystals of bismuth. This allowed high-quality single-crystal X-ray diffraction data to be collected, providing accurate structural parameters for elemental bismuth under ambient conditions.

Three to tango requires a site-specific substitution: heterometallic molecular precursors for high-voltage rechargeable batteries.

Design of heterometallic molecules, especially those containing at least two different metals with close atomic numbers, radii, and the same coordination number/environment is a challenging task. This quest is greatly facilitated by having a heterobimetallic parent molecule that features multiple metal sites with only some of those displaying substitutional flexibility. Recently, a unique heterobimetallic complex LiMn(thd) (thd = 2,2,6,6-tetramethyl-3,5-heptanedionate) has been introduced as a single-source precursor for the preparation of a popular spinel cathode material, LiMnO.

Crystal Growth of Intermetallics from the Joint Flux: Exploratory Synthesis through the Control of Valence Electron Count.

In this study, we modify the flux-growth method for the purpose of exploratory synthesis of ternary intermetallic compounds. Our concept is based on the assumption that valence electron count plays a crucial role in the stability of polar intermetallic compounds of different structure types. Control of the valence electron count parameter is made possible through the use of an excess of two metals having a different number of valence electrons.

A three body problem: a genuine heterometallic molecule a mixture of two parent heterometallic molecules.

This work raises a fundamental question about the "real" structure of molecular compounds containing three different metals: whether they consist of genuine heterometallic species or of a mixture of parent heterometallic species. Heterotrimetallic complex LiCoNi(tbaoac) (, tbaoac = -butyl acetoacetate) has been designed based on the model tetranuclear structure featuring two transition metal sites in order to be utilized as a molecular precursor for the low-temperature preparation of the LiCoNiO battery cathode material. An investigation of the structure of appeared to be very challenging, since the Co and Ni atoms have very similar atomic numbers, monoisotopic masses, and radii as well as the same oxidation state and coordination number/environment.

Expanding the Structural Motif Landscape of Heterometallic β-Diketonates: Congruently Melting Ionic Solids.

The first example of ionic β-diketonates in which both the cation and anion are octahedral coordinatively saturated metal diketonate moieties are reported. Heterometallic tin-transition-metal heteroleptic diketonates were obtained through solid-state redox reactions and are formulated as {[Sn(thd)][M(hfac)]} (M = Mn (1), Fe (2), Co (3); thd = 2,2,6,6-tetramethyl-3,5-heptanedionate, hfac = hexafluoroacetylacetonate). X-ray single-crystal structural investigations along with DART mass spectrometry, multinuclear NMR, and magnetic susceptibility measurements have been used to confirm an assignment of metal oxidation states in compounds 1-3.

Position Assignment and Oxidation State Recognition of Fe and Co Centers in Heterometallic Mixed-Valent Molecular Precursors for the Low-Temperature Preparation of Target Spinel Oxide Materials.

A series of mixed-valent, heterometallic (mixed-transition metal) diketonates that can be utilized as prospective volatile single-source precursors for the low-temperature preparation of MM'O spinel oxide materials is reported. Three iron-cobalt complexes with Fe/Co ratios of 1:1, 1:2, and 2:1 were synthesized by several methods using both solid-state and solution reactions. On the basis of nearly quantitative reaction yields, elemental analyses, and comparison of metal-oxygen bonds with those in homometallic analogues, heterometallic compounds were formulated as [Fe(acac)][Co(hfac)] (1), [Co(hfac)][Fe(acac)][Co(hfac)] (2), and [Fe(hfac)][Fe(acac)][Co(hfac)] (3).

Heterometallic molecular precursors for a lithium-iron oxide material: synthesis, solid state structure, solution and gas-phase behaviour, and thermal decomposition.

Three heterometallic single-source precursors with a Li : Fe = 1 : 1 ratio for a LiFeO oxide material are reported. Heterometallic compounds LiFeL (L = tbaoac (1), ptac (2), and acac(3)) have been obtained on a large scale, in nearly quantitative yields by one-step reactions that employ readily available reagents. The heterometallic precursor LiFe(acac) (3) with small, symmetric substituents on the ligand (acac = pentane-2,4-dionate), maintains a 1D polymeric structure in the solid state that limits its volatility and prevents solubility in non-coordinating solvents.

Volatile Single-Source Precursors for the Low-Temperature Preparation of Sodium-Rare Earth Metal Fluorides.

Heterometallic single-source precursors for the preparation of sodium-rare earth metal fluorides are reported. Fluorinated β-diketonates NaRE(hfac)4 (RE = Y (1), Er (2), and Eu (3); hfac = hexafluoroacetylacetonate) have been obtained on a large scale, in high yield, via one-pot reaction that utilizes commercially available starting reagents. The solid-state structures of the title complexes consist of 1D polymeric chains with alternating [Na] and [RE(hfac)4] units.

Iodobismuthates Containing One-Dimensional BiI4(-) Anions as Prospective Light-Harvesting Materials: Synthesis, Crystal and Electronic Structure, and Optical Properties.

Four iodobismuthates, LiBiI4·5H2O (1), MgBi2I8·8H2O (2), MnBi2I8·8H2O (3), and KBiI4·H2O (4), were prepared by a facile solution route and revealed thermal stability in air up to 120 °C. Crystal structures of compounds 1-4 were solved by a single crystal X-ray diffraction method. 1: space group C2/c, a = 12.