Zintl Ions Research Articles

An Organometallic Erbium Bismuth Cluster Complex Comprising a Bi66- Zintl Ion.

An organometallic erbium bismuth cluster complex, [K(THF)4]2[Cp*2Er2Bi6] (1), featuring a heterometallocubane core was isolated. The cube emerges from the rare Bi66- Zintl ion, bridging two erbium centers for the first time. SQUID magnetometry and ab initio calculations uncovered dominant antiferromagnetic coupling enabled through the chair-like hexabismuth anion. The gained insight will promote the design of future polynuclear magnetic molecules comprising prolate lanthanide ions.

Zintl Ions and Phases Promote the Catalytic Hydrophosphination of Alkynes, Alkenes, and Imines.

Although Zintl ions and phases have been known for more than a century, their application as tools to build organic molecules is underdeveloped. Here, a range of Zintl ions and phases were surveyed in the hydrophosphination of alkynes, alkenes, and imines with diphenylphosphine to afford useful organophosphine products. Further investigations with diphenylphosphine in the absence of the unsaturated organic substrates revealed the formation of the diphenylphosphide anion, allowing for the conclusion that the role of the Zintl species is as an initiator in these transformations.

Synthesis of the (Sn4Bi4)2− Anion by Mild Oxidation of (Sn2Bi2)2−

AbstractReactions involving Zintl ions are typically carried out in N‐based solvents such as liquid ammonia (NH3(l)), ethane‐1,2‐diamine (en), pyridine (py), or acetonitrile (CH3CN). We are currently investigating the application of other solvents as alternatives. Herein, we present the synthesis of the (Sn4Bi4)2− anion, obtained as its [K(crypt‐222)]+ salt (crypt‐222=4,7,13,16,21,24‐hexaoxa‐1,10‐diazabicyclo[8.8.8]hexacosane), from reactions of the binary, pseudo‐tetrahedral Zintl anion (Sn2Bi2)2− in the presence of phosphines as oxidation agents in ortho‐difluorobenzene (o‐DFB). The cluster comprises 38 valence electrons, hence, represents an arachno‐type architecture according to Wade‐Mingos rules. Micro‐X‐ray fluorescence (μ‐XFS) spectroscopy rationalized the elemental composition of the anion, and quantum chemical studies served to compare the stability of possible structural isomers of the global minimum structure.

Snap-shots of cluster growth: structure and properties of a Zintl ion with an Fe3 core, [Fe3Sn18]4.

The endohedral Zintl-ion cluster [Fe3Sn18]4- contains a linear Fe3 core with short Fe-Fe bond lengths of 2.4300(9) Å. The ground state is a septet, with significant σ and π contributions to the Fe-Fe bonds. The Sn18 cage is made up of two partially fused Sn9 fragments, and is structurally intermediate between [Ni2CdSn18]6-, where the fragments are clearly separated and [Pd2Sn18]4-, where they are completely fused. It therefore represents an intermediate stage in cluster growth. Analysis of the electronic structure suggests that the presence of the linear Fe-Fe-Fe unit is an important factor in directing reactions towards fusion of the two Sn9 units rather than the alternative of oligomerization via exo bond formation.

Reductive reactivity of a Zn(I) − Zn(I)-bonded compound toward white phosphorus and beyond

This work reports the selective reduction of a number of small molecules by a Zn(I) − Zn(I)-bonded compound. Reaction of dizinc compound [L2Zn2] [L = CH3C(2,6-iPr2C6H3N)CHC(CH3)(NCH2CH2PPh2)] with white phosphorus generated a trimetallic cluster [(LZn)3(μ, κ2: κ2: κ1-P7)], which contained a zinc-coordinated Zintl ion [P7]3−. The low valent Zn(I) compound [L2Zn2] could also reduce 1-azidoadamantane and diphenyl disulfide to selectively afford Zn(II) hexazene complex [L2Zn2(μ-1,6-Ad2-N6)] and thiolate derivative [LZnSPh], respectively. In contrast, oxidation reaction selectively occurred at the pendant phosphine of ligand backbone when reacting [L2Zn2] with elemental sulfur, whereas Zn(I) − Zn(I) bond remained intact.

Single-molecule magnets bridged by a bismuth Zintl ion

In this issue of <i>Chem</i>, Demir and colleagues report on the synthesis, <i>ab initio</i> calculations, and magnetic behaviors of two organometallic lanthanide bismuth clusters involving an unprecedented Bi₆⁶⁻ Zintl ion. The serendipitous finding sheds light on the design strategies of exchange-coupled single-molecule magnets.

Cd(Sn9)2]6− and [Cd(Ni@Sn9)2]6−: Reactivity and coordination chemistry of empty and Ni-centered [Sn9]4− Zintl ions

To investigate the reactivity of homoatomic clusters [E 9 ] 4− (E = Si-Pb) and intermetalloid clusters [M@E 9 ] q− , the reactions of the Zintl anions [Sn 9 ] 4− and [Ni@Sn 9 ] 4− with the CdMes 2 (Mes = Mesitylene) in the presence of 2.2.2-crypt were carried out. Two new compounds [K(2.2.2-crypt)] 6 [(Sn 9 )Cd(Sn 9 )]•en ( 1 ) and [K(2.2.2-crypt)] 6 [(Ni@Sn 9 )Cd(Ni@Sn 9 )]•en ( 2 ) were afforded. Both 1 and 2 were characterized by single-crystal X-ray diffraction, energy dispersive X-ray (EDX), and electrospray ionization mass spectrometry (ESI-MS), and can be viewed as two [Sn 9 ] 4− or [Ni@Sn 9 ] 4− subunits bridged by Cd ion in an η 3 : η 3 coordination mode. Quantum chemical calculations reveal the relationships between the geometries and electronic structures of clusters 2a , [Ni 3 Ge 18 ] 4− and [Cu 4 @Sn 18 ] 4− . Further electron localization technique (AdNDP method) was performed to explain chemical bonding patterns of 1a . The sandwich-like structure of [Sn 9 CdSn 9 ] 6− and [(Ni@Sn 9 )Cd(Ni@Sn 9 )] 6− and corresponding frontier molecular orbitals.

Organometallic lanthanide bismuth cluster single-molecule magnets

<h2>Summary</h2> Single-molecule magnets (SMMs) are molecules that can retain magnetic polarization in the absence of an external magnetic field and embody the ultimate size limit for spin-based information storage and processing. Multimetallic lanthanide complexes lacking magnetic exchange coupling enable fast relaxation pathways that attenuate the full potential of these species. Employment of diamagnetic heavy main group elements with diffuse orbitals may lead to unprecedented strong coupling. Herein, two bismuth-cluster-bridged lanthanide complexes, [K(THF)₄]₂[Cp∗₂Ln₂Bi₆] (Cp∗ = pentamethylcyclopentadienyl; <b>1-Ln</b>, Ln = Tb, Dy), were synthesized via a solution organometallic approach. The neutral [Ln₂Bi₆] heterometallocubane core features lanthanide centers that are bridged by a rare Bi₆⁶⁻ Zintl ion, which supports strong ferromagnetic interactions between lanthanides. This affords the rare observation of magnetic blocking and open hysteresis loops for superexchange-coupled SMMs comprising solely lanthanide ions. Both compounds constitute the first SMMs containing bismuth donors paving the way for promising synthetic targets for quantum computation.

Synthesis and Structure of Binary Copper/Silver–Arsenic Clusters Derived from Zintl Ion As73–

Comprehensive SummaryPolyarsenides containing coinage metals, [As7Cu(PPh3)]2– (1) and [M2As14]4– (M = Cu, 2; Ag, 3), were synthesized by reactions of the nominal composition K3As7 with Group 11 metal complexes. The possible intermediate, cluster 1, was isolated from the solution phase through subtle changes in reaction conditions in the formation process of complex 2. Hence, we establish the pathway of the bimetallic bridged clusters [Cu2As14]4– by the oxidation of the [As7Cu(PPh3)]2–. Quantum chemical calculations reveal the presence of metallophilic interaction in clusters 2 and 3.

A Structural Diversity of Molecular Alkaline-Earth-Metal Polyphosphides: From Supramolecular Wheel to Zintl Ion.

A series of molecular group 2 polyphosphides has been synthesized by using air‐stable [Cp*Fe(η5‐P5)] (Cp*=C5Me5) or white phosphorus as polyphosphorus precursors. Different types of group 2 reagents such as organo‐magnesium, mono‐valent magnesium, and molecular calcium hydride complexes have been investigated to activate these polyphosphorus sources. The organo‐magnesium complex [(DippBDI−Mg(CH3))2] (DippBDI={[2,6‐ i Pr2C6H3NCMe]2CH}−) reacts with [Cp*Fe(η5‐P5)] to give an unprecedented Mg/Fe‐supramolecular wheel. Kinetically controlled activation of [Cp*Fe(η5‐P5)] by different mono‐valent magnesium complexes allowed the isolation of Mg‐coordinated formally mono‐ and di‐reduced products of [Cp*Fe(η5‐P5)]. To obtain the first examples of molecular calcium‐polyphosphides, a molecular calcium hydride complex was used to reduce the aromatic cyclo‐P5 ring of [Cp*Fe(η5‐P5)]. The Ca‐Fe‐polyphosphide is also characterized by quantum chemical calculations and compared with the corresponding Mg complex. Moreover, a calcium coordinated Zintl ion (P7)3− was obtained by molecular calcium hydride mediated P4 reduction.

Role of Size and Composition on the Design of Superalkalis.

Superalkalis and superhalogens are atomic clusters that mimic the chemistry of alkali and halogen atoms, respectively; the ionization energies of the superalkalis are less than those of alkali atoms, while the electron affinities of superhalogens are larger than those of the halogen atoms. These superions can serve as the building blocks of a new class of supersalts with applications in solar cells, metal-ion batteries, multiferroic materials, and so on. While considerable progress has been made in the design and synthesis of superhalogens, a similar understanding of superalkalis is lacking. Using density functional theory with hybrid exchange-correlation functional and Gaussian basis sets, we have systematically studied the role of size and composition on the properties of two different classes of clusters whose stabilities are governed by the Wade-Mingos polyhedral skeletal electron pair theory. One class belongs to the closo-borane family LimBnXn (m = 1, 2, 3; n = 6, 12; X = H, F, CN), while the other to the Zintl ions Lim[Be@Ge9]. We show that Li3BnXn and Li3[Be@Ge9] clusters are superalkalis with ionization energies as low as 2.84 eV in Li3B6H6. However, contrary to expectation, the ionization energies do not decrease with increasing cluster volume. Instead, ionization energies are linked to the X ligands' electron affinities; the larger the electron affinity, the higher is the ionization energy. The understanding gained here will help in the discovery of superalkalis and, hence, enrich the library of supersalts.

Doped deltahedral organo-Zintl superalkali cations

The doped deltahedral Zintl clusters are known for decades. Here, we report a functionalized doped organo-Zintl clusters [Ge7P2R3](R = CH3, C2H5 & C3H3) derived from the doped [Ge7P2]2− Zintl ion by replacing germanium atoms in deltahedral Ge94− cluster with Phosphorus (P). Using first principle calculation, we show that, it is also possible to design superalkali compounds by using doped deltahedral Zintl ions as a core with suitable organic aliphatic and cyclic ligands. The calculated vertical electron affinities (VEAs) of designed Zintl complexes are lower than alkali metals ionization energy (IE = 3.89–5.34 eV).

Density Functional Treatment on Alkylation of a Functionalized Deltahedral Zintl Cluster.

Density functional theory (DFT) is one of the popular methods to understand the electronic structure of molecular systems based on electronic density. On the basis of this theory, several conceptual DFT descriptors have been developed which can deal with the stability, reactivity, and several other physicochemical properties of molecules. Here, we have taken a nine-atom-functionalized deltahedral Zintl cluster of germanium (Ge) to examine the alkylation reaction mechanism. The study showed that the Zintl cluster having a methyl group as a ligand, [Ge9(CH3)3-], acts as a better nucleophile than the cyanide (-CN)-substituted cluster [Ge9(CN)3-] in terms of different thermodynamic parameters like free energy, enthalpy of activation, reaction energy, etc. A detailed reaction electronic flux analysis reveals the nature of the electronic activity throughout the reaction pathway. The reaction force, Wiberg bond indices, and dual descriptor lend additional support to the reaction mechanism. It has been found that the alkylation reaction between the Zintl ion and the alkyl halide follows a SN2-like mechanism.

The Arachno-Zintl Ion (Sn5 Sb3 )3- and the Effects of Element Composition on the Structures of Isoelectronic Clusters: Another Facet of the Pseudo-Element Concept.

The pseudo‐element concept, in its most general formulation, states that isoelectronic atoms form equal numbers of bonds. Hence, clusters such as Zintl ions usually retain their structure upon isoelectronic replacement of some or all atoms. Here, a deviation from this common observation is presented, namely the formation of (Sn5Sb3)3− (1), a rare example of an eight‐vertex Zintl ion, and an unprecedented example of a Zintl ion synthesized by solution means that has an arachno‐type structure according to the Wade–Mingos rules. Three structure‐types of interest for (Sn5Sb3)3− were identified by DFT calculations: one that matched the X‐ray diffraction data, and two that that were reminiscent of fragments of known clusters. A study on the isoelectronic series of clusters, (SnxSb8−x)2−x (x=0–8), showed that the relative energies of these three isomers vary significantly with composition (independent of electron count) and that each is the global minimum at least once within the series.

The Arachno‐Zintl Ion (Sn5Sb3)3− and the Effects of Element Composition on the Structures of Isoelectronic Clusters: Another Facet of the Pseudo‐Element Concept

AbstractThe pseudo‐element concept, in its most general formulation, states that isoelectronic atoms form equal numbers of bonds. Hence, clusters such as Zintl ions usually retain their structure upon isoelectronic replacement of some or all atoms. Here, a deviation from this common observation is presented, namely the formation of (Sn5Sb3)3− (1), a rare example of an eight‐vertex Zintl ion, and an unprecedented example of a Zintl ion synthesized by solution means that has an arachno‐type structure according to the Wade–Mingos rules. Three structure‐types of interest for (Sn5Sb3)3− were identified by DFT calculations: one that matched the X‐ray diffraction data, and two that that were reminiscent of fragments of known clusters. A study on the isoelectronic series of clusters, (SnxSb8−x)2−x (x=0–8), showed that the relative energies of these three isomers vary significantly with composition (independent of electron count) and that each is the global minimum at least once within the series.

Unusually large 254 Atoms Counter‐Ion for 5 Atoms [Ge5]2– Cluster

Abstract. With the attempt to synthesize Nb‐enclosed germanium Zintl cluster ion in ethylenediamine (en) / toluene solution, the reaction of K4Ge9/Na4Ge9 with Nb(mes)2 (mes = mesitylene) gives unexpected 18‐crown‐6 cleavage product of [K14Na2(NbO2)2(C8H16O5)8](Ge5) (en)·solv in the form of very air‐sensitive, light‐brown, plate‐like crystals. This unique compound crystallizes in monoclinic Pn (No. 7) space group, the cleavage of crown linked the 14 potassium, 2 sodium, and 2 niobium atoms into the bulky 2+ charged cation, which balances the [Ge5]2– anion. This compound represents the rare example of heteronuclear metal alkoxide / Zintl ion hybrid.

Intermediates and products of the reaction of Zn(ii) organyls with tetrel element Zintl ions: cluster extension versus complexation.

The discovery of low-valent Zn compounds resulted in the renaissance of organometallic Zn complexes. Polyhedral clusters of tetrel elements can interact with Zn atoms either as Lewis donors or by incorporation of the Zn atoms as additional cluster vertices. Herein we report the reactions of ZnR2 (R = ethyl (Et), pentamethylcyclopentadiene (Cp*), phenyl (Ph) and 1,3,5-trimethylbenzene (Mes)) with Zintl ions of the types [E4]4- (E = Ge, Sn) and [Ge9]4- in liquid ammonia. Besides the desired Zintl ion complexes, intermediates were isolated that give insight into the reaction of organo Zn compounds in liquid ammonia. Three ions, [(η3:η3-Ge4)(ZnEt)2]2- (1a), [(η2-Sn4)Zn(η2-Sn4)]6- (2a) and [(η4-Ge9)(ZnEt)]3- (3a), were obtained and characterized by means of single crystal X-ray diffraction analysis. Furthermore, amides [(ZnPh2)2(μ2-NH2)2]2- (4a) and {[Zn(μ2-NH2)4][(ZnEt)2(μ2-NH2)2]2}2- (5a) were formed during the reactions, together with the addition products [ZnPh3]- (6a) and [ZnMes3]- (7a) and an anion [Cp*]- (8a), suggesting the following reaction sequence: in liquid ammonia the Zintl anions form amides, which then serve as ligands for ZnR2 molecules. The NH2- ligands weaken the corresponding Zn-R bonds, and thus bond cleavage and the addition of the Zintl anion to the Zn ion can take place, additionally promoted by the trapping of the leaving group R- by unreacted Zn organyls with the formation of [ZnR3]-.

On the position of La, Lu, Ac and Lr in the periodic table: a perspective

The periodic table of elements, organised as blocks of elements that contain similar properties, occupies a central role in chemistry. However, the position of some of the elements in the periodic table is a debate that has been ensuing over the past one and a half long centuries. Particularly, the positions of lanthanum (La), lutetium (Lu), actinium (Ac) and lawrencium (Lr) in the periodic table have been quite controversial. Different kinds of studies carried out by various research groups have yet left the fate of these elements undecided as the results of these investigations suggested that these elements could potentially be placed in the d-block, p-block or all four in the f-block. Our recent work looked into this question from a new perspective, involving encapsulation of La, Lu, Ac and Lr into Zintl ion clusters, Pb122− and Sn122−. These clusters were chosen as they provide a fitting environment for the determination of structural, thermodynamic and electronic properties of the encapsulated species. Various results that have been evaluated and subsequently analysed (Joshi et al. in Phys. Chem. Chem. Phys. 20:15253–15272, 2018) in order to seek out similarities and differences for making justified conclusions about the placement of all these four elements in the periodic table are the subject matter of this review article. This review highlights a unique methodology wherein Ln and An encapsulated Pb122− and Sn122− clusters provided in-depth insights on the long-drawn controversy: positions of lutetium, lawrencium, lanthanum and actinium in the modern periodic table. Electronic, thermodynamic and structural parameters have been comprehensively investigated by DFT to yield a justified conclusion.

Record Low Ionization Potentials of Alkali Metal Complexes with Crown Ethers and Cryptands.

Electronic properties of series of alkali metals complexes with crown ethers and cryptands were studied via DFT hybrid functionals. For [M([2.2.2]crypt)] (M=Li, Na, K) extremely low (1.70-1.52 eV) adiabatic ionization potentials were found. Such low values of ionization energies are significantly lower than those of alkali metal atoms. Thus, the investigated complexes can be defined as superalkalis. As a result, our investigation opens up new directions in the designing of chemical species with record low ionization potentials and extends the explanation of the ability of the cryptates and alkali crown ether complexes to stabilize multiple charged Zintl ions.

Optical and vibrational properties of nickel integrated germanium Zintl ion clusters

Vibrational and optical properties of Ni-Ge clusters ([Ni2Ge9(PPh3)]2−, [Ni6Ge13(CO)5]4−) have been investigated via UV–Vis, FTIR, and Fluorescence spectroscopies. Moreover, frequency and time-dependent (TD) electronic transition calculations have been performed to better characterize experimental findings, due to the scarcity of vibrational and optical spectroscopic studies on these type of clusters in the literature. UV–Vis spectroscopic analyses demonstrate a broad absorption band, with a maximum at 270 nm for both Ni-Ge clusters. [Ni6Ge13(CO)5]4− cluster band is broader and has a shoulder around 320 nm. Vibrational modes associated with the clusters appear at low-frequency region of FTIR spectra. [Ni6Ge13(CO)5]4− cluster spectrum is very rich as expected due to higher number of atoms in the cluster structure. Main vibrational modes of [Ni2Ge9(PPh3)]2− are observed at 318(m) cm−1 and 130(w) cm−1, and those of [Ni6Ge13(CO)5]4− appear at 232(s) cm−1 and 155(s) cm−1. Similarities observed between simulated and experimental spectra strongly support a stable, isolated cluster behavior in the crystal structure. Fluorescence spectroscopic analysis demonstrates that excitation of [Ni2Ge9(PPh3)]2− and [Ni6Ge13(CO)5]4− clusters at 260 nm has resulted relatively strong and broad emissions at 400 nm and 410 nm, respectively. [Ni2Ge9(PPh3)]2− and [Ni6Ge13(CO)5]4− clusters are two of the very few examples of Zintl ion clusters that have been characterized with UV–Vis and FTIR spectroscopic analyses, and the only ones that have been studied with fluorescence spectroscopy.