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In this work, we synthesize naked tin cluster anion Sn368−, representing the first example of pure Sn nanowire assembled through oxidative coupling reactions of a super atomic cluster Sn94−. Theoretical analysis confirm the presence of aromaticity for each Sn9 unit showing four adjacent aromatic subunits bridged by parallel Sn–Sn bonds. [ABSTRACT FROM AUTHOR]

A new Zintl cluster, [(Ni@Sn9)In(Ni@Sn9)]5−, has been isolated in two distinct isomeric forms, one where both Ni@Sn9 units are coordinated to the bridging In atom in an η3- mode, the other where one is η3- and the other η4-. Density functional theory indicates that the energetic separation between these two structures is minimal, suggesting that crystal packing plays a decisive role in the structural chemistry. A comparison of the electronic structure of [(Ni@Sn9)In(Ni@Sn9)]5− with [(Ni@Ge9)Ni(Ni@Ge9)]4−, which has four fewer valence electrons, sheds some light on possible mechanisms that lead to the fusion of cluster fragments. [ABSTRACT FROM AUTHOR]

We report here the synthesis and characterization of two endohedral Zintl-ion clusters, [Fe 4 Sn 18 ] 4- and [Fe 4 Pb 18 ] 4- , which contain rhombic Fe 4 cores. The Fe-Fe bond lengths are all below 2.5 Å, distinctly shorter than in the corresponding Cu clusters, indicating the presence of Fe-Fe bonding. Subtle differences in the structure of the Fe 4 core between the two clusters suggest that the change in tetrel element causes a change in electronic ground state, with a very short Fe-Fe bond length of 2.328 Å present across the diagonal of the rhombus in the lead case., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The endohedral Zintl-ion cluster [Fe 3 Sn 18 ] 4- contains a linear Fe 3 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 Sn 18 cage is made up of two partially fused Sn 9 fragments, and is structurally intermediate between [Ni 2 CdSn 18 ] 6- , where the fragments are clearly separated and [Pd 2 Sn 18 ] 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 Sn 9 units rather than the alternative of oligomerization via exo bond formation., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The superconducting hydrides LaH 10 , EuH 9 and UH 8 are studied using chemically intuitive bonding analysis of periodic and molecular models. We find trends in the crystallographic and electronic structures of the materials by focusing on chemically meaningful building blocks in the predicted H sublattices. Atomic charge calculations, using two complementary techniques, allow us to assign oxidation states to the metals and divide the H sublattice into neutral and anionic components. Cubic [H 8 ] q- clusters are an important structural motif, and molecular orbital analysis of this cluster in isolation shows the crystal structures to be consistent with our oxidation state assignments. Crystal orbital Hamilton population analysis confirms the applicability of the cluster model to the periodic electronic structure. A Jahn-Teller distortion predicted by MO analysis rationalises the distortion observed in a prior study of EuH 9 . The impact of this distortion on superconductivity is determined, and implications for crystal structure prediction in other metal-hydrogen systems are discussed. Additionally, the performance of electronic structure analysis methods at high pressures are tested and recommendations for future studies are given. These results demonstrate the value of simple bonding models in rationalizing chemical structures under extreme conditions., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

In this work, we synthesize naked tin cluster anion Sn 36 8- , representing the first example of pure Sn nanowire assembled through oxidative coupling reactions of a super atomic cluster Sn 9 4- . Theoretical analysis confirm the presence of aromaticity for each Sn 9 unit showing four adjacent aromatic subunits bridged by parallel Sn-Sn bonds.

The development of rational synthetic routes to inorganic arsenide compounds is an important goal because these materials are finding applications in many areas of materials science. In this paper, we show that the binary crown clusters [M@As 8 ] 3- (M = Nb, Ta) can be used as synthetic precursors which, when combined with ZnMes 2 , generate ternary intermetalloid clusters with 12-vertex cages, {M@[As 8 (ZnMes) 4 ]} 3- (M = Nb, Ta). Structural studies are complemented by mass spectrometry and an analysis of the electronic structure using DFT. The synthesis of these clusters presents new opportunities for the construction of As-based nanomaterials., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

We present a detailed experimental and computational investigation of the influence of pressure on the mixed-anion oxyhydride phase Ba 2 YHO 3 , which has recently been shown to support hydride conductivity. The unique feature of this layered perovskite is that the oxide and hydride anions are segregated into distinct regions of the unit cell, in contrast to the disordered arrangement in closely related Ba 2 ScHO 3 . Density functional theory (DFT) calculations reveal that the application of pressure drives two sequential B 1- B 2 transitions in the interlayer regions from rock salt to CsCl-type ordering, one in the hydride-rich layer at approximately 10 GPa and another in the oxide-rich layer at 35-40 GPa. To verify the theoretical predictions, we experimentally observe the structural transition at 10 GPa using high-pressure X-ray diffraction (XRD), but the details of the structure cannot be solved due to peak broadening of the XRD patterns. We use DFT to explore the structural impact of pressure on the atomic scale and show how the pressure-dependent properties can be understood in terms of simple electrostatic engineering.

The [Nb@As 8 ] 3- anion was first isolated from solution in 1986, and a number of isostructural [M@Pn 8 ] n - clusters (M = Nb, Cr, or Mo; Pn = As or Sb; n = 2 or 3) have since been reported. We show here how anions of this class can be used as synthetic precursors that, in combination with sources of low-valent late transition metals (Cu and Ag), generate ternary polyarsenide cluster anions with unprecedented structural motifs. Chain type [MM'As 16 ] 4- (M = Nb or Ta; M' = Cu or Ag) units are found in compounds 2-5 . These clusters contain a nortricyclane-like As 7 cage and a [M@As 8 ] crown, linked by a single As atom, and represent a fusion of two quite distinct branches of polyarsenide chemistry. Our analysis of the electronic structure confirms that the cluster retains many of the features of the component units. Electrospray ionization mass spectrometry reveals a series of smaller component ions containing 8-12 As atoms, the density functional theory-computed structures of which can be understood in terms of the pseudoelement concept. This work not only presents a new type of coordination mode for As clusters but also offers a point of entry for the rational design of multinary arsenic-based materials.

The anionic cluster [Fe 2 @Ge 16 ] 4- has been characterized and shown to be isostructural to the known D 2 h -symmetric α isomer of the cobalt analogue [Co 2 @Ge 16 ] 4- . Together with the known pair of compounds [Co@Ge 10 ] 3- and [Fe@Ge 10 ] 3- , the title compound completes a set of four closely related germanium clusters that allow us to explore how the metal-metal and metal-cage interactions evolve as a function of size and of the identity of the metal. The results of spin-unrestricted density functional theory (DFT) and multiconfigurational self-consistent field (MC-SCF) calculations present a consistent picture of the electronic structure where transfer of electron density from the metal to the cage is significant, particularly in the Fe clusters where the exchange stabilization of unpaired spin density is an important driving force.

We report the synthesis of two new cluster anions, [Cu 4 @E 18 ] 4- (E = Sn, Pb), in which a Cu 4 subunit is incorporated into a continuous E 18 tetrel cage. Both anions are characterized by X-ray crystallography and mass spectrometry, complemented by quantum-chemical calculations that highlight the relationships to known Zintl clusters, including the stannaspherenes and plumbaspherenes [M@Sn 12 ] q - and [M@Pb 12 ] q - , the Matryoshka bronze [Sn@Cu 12 @Sn 20 ] 12- , and also [Pd 2 @E' 18 ] 4- (E' = Ge, Sn).

High-pressure X-ray diffraction measurements on the layered oxyhydrides Sr 2 VO 3 H and Sr 3 V 2 O 5 H 2 reveal that both compounds undergo a pressure-induced rock-salt to CsCl ( B 1- B 2) structural transition, similar to those observed in binary compounds (oxides, halides, chalcogenides, etc.). This structural transition, observed at 43 and 45 GPa in Sr 2 VO 3 H and Sr 3 V 2 O 5 H 2 , respectively, relieves almost all of the accumulated strain on the infinite V-O-V ladders, such that the V-O bond lengths are almost identical at 0 and 50 GPa but are substantially compressed at intermediate pressures. The resistances of both materials with 1-dimensional VO ladders decrease with increasing pressure, but unlike SrVO 2 H that contains 2-dimensional VO 2 sheets, they remain insulating even at the highest accessible pressures. The reduction in dimensionality from planar to linear VO networks reduces the dispersion of the V-O π bands that define the band gap and leads to insulating behavior at all measured pressures.

A new Zintl cluster, [(Ni@Sn 9 )In(Ni@Sn 9 )] 5- , has been isolated in two distinct isomeric forms, one where both Ni@Sn 9 units are coordinated to the bridging In atom in an η 3 - mode, the other where one is η 3 - and the other η 4 -. Density functional theory indicates that the energetic separation between these two structures is minimal, suggesting that crystal packing plays a decisive role in the structural chemistry. A comparison of the electronic structure of [(Ni@Sn 9 )In(Ni@Sn 9 )] 5- with [(Ni@Ge 9 )Ni(Ni@Ge 9 )] 4- , which has four fewer valence electrons, sheds some light on possible mechanisms that lead to the fusion of cluster fragments.

Topochemical reduction of the double-perovskite oxide Sr 2 FeIrO 6 under dilute hydrogen leads to the formation of Sr 2 FeIrO 4 . This phase consists of ordered infinite sheets of apex-linked Fe 2+ O 4 and Ir 2+ O 4 squares stacked with Sr 2+ cations and is the first report of Ir 2+ in an extended oxide phase. Plane-wave density functional theory calculations indicate high-spin Fe 2+ (d 6 , S = 2) and low-spin Ir 2+ (d 7 , S = 1 / 2 ) configurations for the metals and confirm that both ions have a doubly occupied d z 2 orbital, a configuration that is emerging as a consistent feature of all layered oxide phases of this type. The stability and double occupation of d z 2 in the Ir 2+ ions invites a somewhat unexpected analogy to the extensively studied Ir 4+ ion as both ions share a common near-degenerate (d xy/ xz/ yz ) 5 valence configuration. On cooling below 115 K, Sr 2 FeIrO 4 enters a magnetically ordered state in which the Ir and Fe sublattices adopt type II antiferromagnetically coupled networks which interpenetrate each other, leading to frustration in the nearest-neighbor Fe-O-Ir couplings, half of which are ferromagnetic and half antiferromagnetic. The spin frustration drives a symmetry-lowering structural distortion in which the four equivalent Ir-O and Fe-O distances of the tetragonal I4/ mmm lattice split into two mutually trans pairs in a lattice with monoclinic I112/ m symmetry. This strong magneto-lattice coupling arises from the novel local electronic configurations of the Fe 2+ and Ir 2+ cations and their cation-ordered arrangement in a distorted perovskite lattice.