Synthesis, Structure and Thermal Property of [(n-C16H33)N(CH3)3]2[TiF6]·2H2O

A new compound dicetyltrimethylammonium hexafluorotitanium dihydrate, [(n-C₁₆H₃₃)N(CH₃)₃]₂[TiF₆]·2H₂O (compound 1), was hydrothermally synthesized at 150 °C and characterized by single crystal X-ray diffraction, Fourier-transform infrared (FTIR) spectroscopy, elemental analysis, and thermogravimetric analysis. Compound 1 crystallizes in the monoclinic system, space group C2/c. It consists of hexafluorotitanium cations [TiF₆]²⁻, water molecular (H₂O), and cetyltrimethylammonium ions [(n-C₁₆H₃₃)N(CH₃)₃]⁺, which are connected together by extensive hydrogen bonding.     

A family of three-dimensional porous coordination polymers with general formula (Kat)2[{M(H2O)n}3{Re6Q8(CN)6}2]·xH2O (Q=S, Se; n=1.5, 2)

The X-ray crystal structures of a series of new compounds (H₃O)₂[{Mn(H₂O)_1.5}₃{Re₆Se₈(CN)₆}₂]·19H₂O (1), (Me₄N)₂[{Co(H₂O)_1.5}₃{Re₆S₈(CN)₆}₂]·13H₂O (2), (Me₄N)₂[{Co(H₂O)_1.5}₃{Re₆Se₈(CN)₆}₂]·3H₂O (3), (Et₄N)₂[{Mn(H₂O)₂}₃{Re₆Se₈(CN)₆}₂]·6.5H₂O (4), (Et₄N)₂[{Ni(H₂O)₂}₃{Re₆S₈(CN)₆}₂]·6.5H₂O (5), and (Et₄N)₂[{Co(H₂O)₂}₃{Re₆S₈(CN)₆}₂]·10H₂O (6) are reported. All six compounds are isostructural crystallizing in cubic space group with four formulae per unit cell. For compounds 1, 3-5 the following parameters were found: (1) a=19.857(2) Å, R1=0.0283; (3 at 150 K) a=19.634(1) Å, R1=0.0572; (4) a=20.060(2) Å, R1=0.0288; (5) a=19.697(2) Å, R1=0.0224. The structures consist three-dimensional cyano-bridged framework formed by cyano cluster anions [Re₆Q₈(CN)₆]⁴⁻, Q=S, Se and transition metal cations, M²⁺=Mn²⁺, Co²⁺, Ni²⁺. Water molecules and large organic cations Me₄N⁺ and Et₄N⁺ are included in cavities of this framework. Porosity of the framework, its ability to accommodate different cations and water molecules by little changes in the structure, as well as distortion of coordination framework under loss of water of crystallization is discussed.     

Relationship between interlayer hydration and photocatalytic water splitting of A′1−xNaxCa2Ta3O10·nH2O (A′=K and Li)

Partial replacement of alkaline metals in anhydrous KCa₂Ta₃O₁₀ and LiCa₂Ta₃O₁₀ was studied to control interlayer hydration and photocatalytic activity for water splitting under UV irradiation. A′_1−xNa_xCa₂Ta₃O₁₀·nH₂O (A′=K and Li) samples were synthesized by ion exchange of CsCa₂Ta₃O₁₀ in mixed molten nitrates at 400 °C. In K_1−xNa_xCa₂Ta₃O₁₀·nH₂O, two phases with the orthorhombic (C222) and tetragonal (I4/mmm) structures were formed at x?0.7 and x?0.5, respectively. Upon replacement by Na⁺ having a larger enthalpy of hydration (ΔH_h⁰), the interlayer hydration occurred at x?0.3 and the hydration number (n) was increased monotonically with an increase of x. Li_1−xNa_xCa₂Ta₃O₁₀·nH₂O showed a similar hydration behavior, but the phase was changed from I4/mmm (x<0.5, n∼0) via P4/mmm (x∼0.5, n∼1) to I4/mmm (x∼1.0, n∼2). The photocatalytic activities of these systems after loading 0.5 wt% Ni were quite different each other. K_1−xNa_xCa₂Ta₃O₁₀·nH₂O exhibited the activity increasing in consistent with n, whereas Li_1−xNa_xCa₂Ta₃O₁₀·nH₂O exhibited the activity maximum at x=0.77, where the rates of H₂/O₂ evolution were nearly doubled compared with those for end-member compositions (x=0 and 1).     

Structural studies of five layer Aurivillius oxides: A2Bi4Ti5O18 (A=Ca, Sr, Ba and Pb)

The room temperature structures of the five layer Aurivillius phases A₂Bi₄Ti₅O₁₈ (A=Ca, Sr, Ba and Pb) have been refined from powder neutron diffraction data using the Rietveld method. The structures consist of [Bi₂O₂]²⁺ layers interleaved with perovskite-like [A₂Bi₂Ti₅O₁₆]²⁻ blocks. The structures were refined in the orthorhombic space group B2eb (SG. No. 41), Z=4, and the unit cell parameters of the oxides are a=5.4251(2), b=5.4034(1), c=48.486(1); a=5.4650(2), b=5.4625(3), c=48.852(1); a=5.4988(3), b=5.4980(4), c=50.352(1); a=5.4701(2), b=5.4577(2), c=49.643(1) for A=Ca, Sr, Ba and Pb, respectively. The structural features of the compounds were found similar to n=2-4 layers bismuth oxides. The strain caused by mismatch of cell parameter requirements for the [Bi₂O₂]²⁺ layers and perovskite-like [A₂Bi₂Ti₅O₁₆]²⁻ blocks were relieved by tilting of the TiO₆ octahedra. Variable temperature synchrotron X-ray studies for Ca and Pb compounds showed that the orthorhombic structure persisted up to 675 and 475 K, respectively. Raman spectra of the compounds are also presented.     

High Lithium Capacity MxV2O5Ay·nH2O for Rechargeable Batteries

The aqueous synthesis and electrochemical properties of nanocrystalline M_xV₂O₅A_y·nH₂O are described. It is easily and quickly prepared by precipitation from acidified vanadate solutions. M_xV₂O₅A_y·nH₂O has been characterized by X-ray powder diffraction, electron microscopy, TGA, chemical analyses, and electrochemical studies. The atomic structure is related to that of xerogel-derived V₂O₅·nH₂O. In M_xV₂O₅A_y·nH₂O, M is a cation from the starting vanadate salt and A is an anion from the mineral acid. This material exhibits high, reversible Li capacity and may be considered for use in a cathode in primary and secondary batteries. The lithium capacity of an electrode composed of M_xV₂O₅A_y·nH₂O/EPDM/carbon (88/4/8) is ∼380(mA h)/g (C/80 rate) and the energy density is ∼1000(W h)/kg (120-μm-thick cathode, 4-1.5 V, versus Li metal anode). Critical parameters identified in the synthesis of M_xV₂O₅A_y·nH₂O, with respect to achieving high Li-ion insertion capacity, are acid/vanadium ratio, starting vanadate salt, and temperature. Inclusion of carbon black in the synthesis yields a composite that maintains the high Li capacity, lowers the electrochemical-cell polarization, and preserves the lithium capacity at higher discharge rates. Li-ion coin cells, using pre-lithiated graphite anodes, exhibit electrochemical performance comparable to that of Li-metal coin cells.     

A rare multi-coordinate tellurite, NH4ATe4O9·2H2O (ARb or Cs): The occurrence of TeO3, TeO4, and TeO5 Polyhedra in the same material

Two new tellurites, NH₄RbTe₄O₉·2H₂O and NH₄CsTe₄O₉·2H₂O have been synthesized and characterized. The compounds were synthesized hydrothermally, in near quantitative yields, using the alkali metal halide, TeO₂, and NH₄OH as reagents. The iso-structural materials exhibit layered, two-dimensional structural topologies consisting of TeO_x (x=3, 4, or 5) polyhedra separated by NH₄⁺, H₂O, Rb⁺ or Cs⁺ cations. Unique to these materials is the presence of TeO₃, TeO₄, and TeO₅ polyhedra. Thermogravimetric and infrared spectroscopic data are also presented. Crystal data: NH₄RbTe₄O₉·2H₂O: Monoclinic I2/a (no. 15), a=18.917(3) Å, b=6.7002(11) Å, c=21.106(5) Å, β=101.813(2)°, V=2618.5(9) Å³, Z=8; NH₄CsTe₄O₉·2H₂O: Monoclinic I2/a (no. 15), a=18.9880(12) Å, b=6.7633(4) Å, c=21.476(2) Å, β=102.3460(10)°, V=2694.2(3) Å³, Z=8.     

The crystal structure of the monohydrate R2Mo6O21·H2O (R=Pr, Nd, Sm, and Eu): a layer structure containing disordered [Mo2O7] groups

Although R₂O₃:MoO₃=1:6 (R=rare earth) compounds are known in the R₂O₃-MoO₃ phase diagrams since a long time, no structural characterization has been achieved because a conventional solid-state reaction yields powder samples. We obtained single crystals of R₂Mo₆O₂₁·H₂O (R=Pr, Nd, Sm, and Eu) by thermal decomposition of [R₂(H₂O)₁₂Mo₈O₂₇]·nH₂O at around 685-715 °C for 2 h, and determined their crystal structures. The simulated XRD patterns of R₂Mo₆O₂₁·H₂O were consistent with those of previously reported R₂O₃:MoO₃=1:6 compounds. All R₂Mo₆O₂₁·H₂O compounds crystallize isostructurally in tetragonal, P4/ncc (No. 130), a=8.9962(5), 8.9689(6), 8.9207(4), and 8.875(2) Å; c=26.521(2), 26.519(2), 26.304(2), and 26.15(1) Å; Z=4; R₁=0.026, 0.024, 0.024, and 0.021, for R=Pr, Nd, Sm, and Eu, respectively. The crystal structure of R₂Mo₆O₂₁·H₂O consists of two [Mo₂O₇]²⁻-containing layers (A and B layers) and two interstitial R(1)³⁺ and R(2)³⁺ cations. Each [Mo₂O₇]²⁻ group is composed of two corner-sharing [MoO₄] tetrahedra. The [Mo₂O₇]²⁻ in the B layer exhibits a disorder to form a pseudo-[Mo₄O₉] group, in which four Mo and four O sites are half occupied. R(1)³⁺ achieves 8-fold coordination by O²⁻ to form a [R(1)O₈] square antiprism, while R(2)³⁺ achieves 9-fold coordination by O²⁻ and H₂O to form a [R(2)(H₂O)O₈] monocapped square antiprism. The disorder of the [Mo₂O₇]²⁻ group in the B layer induces a large displacement of the O atoms in another [Mo₂O₇]²⁻ group (in the A layer) and in the [R(1)O₈] and [R(2)(H₂O)O₈] polyhedra. A remarkable broadening of the photoluminescence spectrum of Eu₂Mo₆O₂₁·H₂O supported the large displacement of O ligands coordinating Eu(1) and Eu(2).     

New alkaline earth-zirconium oxalates M2Zr(C2O4)4·nH2O (M=Ba, Sr, Ca) synthesis, crystal structure and thermal behavior

Three new alkaline earth-zirconium oxalates M₂Zr(C₂O₄)₄·nH₂O have been synthesized by precipitation methods for M=Ba, Sr, Ca. For each compound the crystal structure was determined from single crystals obtained by controlled diffusion of M²⁺ and Zr⁴⁺ ions through silica gel containing oxalic acid. Ba₂Zr(C₂O₄)₄·7H₂O, monoclinic, space group C2/c, a=9.830(2), b=29.019(6), , , , Z=4, R=0.0427; Sr₂Zr(C₂O₄)₄·11H₂O, tetragonal, space group I4₁/acd, a=16.139(4), , ,Z=8, R=0.0403; Ca₂Zr(C₂O₄)₄·5H₂O, orthorhombic, space group Pna2₁, a=8.4181(5), b=15.8885(8), , , Z=4, R=0.0622. The structures of the three compounds consist of chains of edge-shared MO₆(H₂O)_x (x=2 or 3) polyhedra connected to ZrO₈ polyhedra through oxalate groups. Depending on the arrangement of chains, the ZrO₈ polyhedron geometry (dodecahedron or square antiprism) and the connectivity, two types of three-dimensional frameworks are obtained. For the smallest M²⁺ cations (Sr²⁺, Ca²⁺), large tunnels are obtained, running down the c direction of the unit cell, which can accommodate zeolitic water molecules. For the largest Ba²⁺ cation, the second framework is formed and is closely related to that of Pb₂Zr(C₂O₄)₄·nH₂O. The decomposition at 800°C into strontium carbonate, barium carbonate or calcium oxide and MZrO₃ (M=Sr, Ba, Ca) perovskite is reported from thermal analyses studies and high temperature X-ray powder diffraction.     

Structure property relationships in the ATi2O4 (A=Na, Ca) family of reduced titanates

Reduced titanates in the ATi₂O₄ (A=Li, Mg) spinel family exhibit a variety of interesting electronic and magnetic properties, most notably superconductivity in the mixed-valence spinel, Li_1+xTi_2−xO₄. The sodium and calcium analogs, NaTi₂O₄ and CaTi₂O₄, each differ in structure, the main features of which are double rutile-type chains composed of edge-sharing TiO₆ octahedra. We report for the first time, the properties and band structures of these two materials. XANES spectroscopy at the Ti K-edge was used to probe the titanium valence. The absorption edge position and the pre-edge spectral features observed in the XANES data confirm the assignment of Ti³⁺ in CaTi₂O₄ and mixed-valence Ti³⁺/Ti⁴⁺ in NaTi₂O₄. Temperature-dependent resistivity and magnetic susceptibility studies are consistent with the classification of both NaTi₂O₄ and CaTi₂O₄ as small band-gap semiconductors, although changes in the high-temperature magnetic susceptibility of CaTi₂O₄ suggest a possible insulator-metal transition near 700 K. Band structure calculations agree with the observed electronic properties of these materials and indicate that while Ti-Ti bonding is of minimal importance in NaTi₂O₄, the titanium atoms in CaTi₂O₄ are weakly dimerized at room temperature.     

Controlled synthesis of single-crystal VOx·nH2O nanoribbons via a hydrothermal reduction method

VO_x·nH₂O (2.0?x?2.5) nanoribbons have been synthesized by direct hydrothermal processing of the aqueous solution of NH₄VO₃ and polyethylene glycol 400 (PEG-400) at pH 3.5-5.5. Techniques of XRD, SEM, TEM, HRTEM, ED, and XPS have been used to characterize the structure, morphology, and composition of the nanoribbons. The VO_x·nH₂O nanoribbons are up to ∼200 μm in length, 100-150 nm in width, 20-30 nm in thickness, and grow along the [010] direction. The ratios of V⁴⁺ to V⁵⁺ in the products can be readily controlled by carefully adjusting the periods of reaction time. PEG carries the roles of both transport and reducing agent. A coordination self-assembly mechanism was proposed to elucidate the formation of the VO_x·nH₂O nanoribbons.     

Thermogravimetric investigations on A(H2O)6BX6 complexes and the formation of ABX6 and ABO3 structures

Thermogravimetry (TG) of A(H₂O)₆BX₆ complexes are presented, with A  Cd²⁺, Co²⁺, Cu²⁺, Fe²⁺, Mg²⁺, Mn²⁺, Ni²⁺, Pb²⁺, Zn²⁺, BSi⁴⁺, Sn⁴⁺, Ti⁴⁺, Zr⁴⁺, and XCl^?, F^?. On a selected number of complexes, differential thermal analyses (DTA) and differential scanning calorimetric measurements (DSC) have been performed. It was found possible to synthesize most complexes including Cd(H₂O)₆TiF₆ as single crystals. The hexafluoride and the titanate compounds are formed from the corresponding cadmium hexaquo—hexafluoride complex. The cadmium titanate could be made either in the ilmenite or in the perovskite structure. The decomposition programs for the preparation of NiTiO₃ and CdTiO₃ are presented.The hexaquo—hexahalide complexes, in general, show one of two decomposition types. The intermediate product in one type is the metal(II) fluoride AX₂ and in the other the mixed hexahalide compounds ABX₆. Which type of decomposition occurs depends on the anion BX^2?₆.     

Syntheses and characterization of zero-dimensional molybdoantimonites, A2(Mo4Sb2O18) (A=Y, La, Nd, Sm, Gd and Dy)

Six new isostructural A₂(Mo₄Sb₂O₁₈) (A=Y, La, Nd, Sm, Gd and Dy) compounds have been synthesized by solid-state reactions and characterized by single crystal X-ray diffraction and spectroscopic techniques. They crystallize in C2/c space group with 4 formula units and contain A³⁺ cations and discrete centrosymmetric anionic (Mo₄Sb₂O₁₈)⁶⁻ aggregates, made of tetrahedral MoO₄ and disphenoidal SbO₄ moieties. They exhibit characteristic Sb³⁺ photoluminescence.     

Preparation, spectroscopic properties of 1,4-di (N,N-diisopropylacetamido)-2,3(1H,4H)-quinoxalinedione (L) lanthanide complexes and the supramolecular structure of [Nd2L2(NO3)6(H2O)2]·H2O

The reaction of lanthanide nitrate with 1,4-di (N,N-diisopropylacetamido)-2,3(1H,4H)-quinoxalinedione (L) yields six novel Ln(III) complexes ([Ln₂L₂(NO₃)₆(H₂O)₂]·H₂O) which are characterized by elemental analysis, thermogravimetric analysis (TGA), conductivity measurements, IR, electronic and ¹H NMR spectroscopies. A new quinoxalinedione-based ligand is used as antenna ligand to sensitize the emission of lanthanide cations. The lowest triplet state energy level of the ligand in the nitrate complex matches better to the resonance level of Eu(III) and Sm(III) than Tb(III) and Dy(III) ion. The f-f fluorescence is induced in the Eu³⁺ and Sm³⁺ complexes by exciting into the π-π* absorptions of the ligand in the UV. Furthermore, the crystal structures of a novel binuclear complex [Nd₂L₂(NO₃)₆(H₂O)₂]·H₂O has been determined by single-crystal X-ray diffraction. The binuclear [Nd₂L₂(NO₃)₆(H₂O)₂]·H₂O complex units are linked by the intermolecular hydrogen bonds and π-π interactions to form a two-dimensional (2-D) layer supramolecule.     

Electronic structure and photocatalytic properties of ABi2Ta2O9 (A=Ca, Sr, Ba)

A new series of layered perovskite photocatalysts, ABi₂Ta₂O₉ (A=Ca, Sr, Ba), were synthesized by the conventional solid-state reaction method and the crystal structures were characterized by powder X-ray diffraction. The results showed that the structure of ABi₂Ta₂O₉ (A=Ca, Sr) is orthorhombic, while that of BaBi₂Ta₂O₉ is tetragonal. First-principles calculations of the electronic band structures and density of states (DOS) revealed that the conduction bands of these photocatalysts are mainly attributable to the Ta 5d+Bi 6p+O 2p orbitals, while their valence bands are composed of hybridization with O 2p+Ta 5d+Bi 6s orbitals. Photocatalytic activities for water splitting were investigated under UV light irradiation and indicated that these photocatalysts are highly active even without co-catalysts. The formation rate of H₂ evolution from an aqueous methanol solution is about 2.26 mmol h^-1 for the photocatalyst SrBi₂Ta₂O₉, which is much higher than that of CaBi₂Ta₂O₉ and BaBi₂Ta₂O₉. The photocatalytic properties are discussed in close connection with the crystal structure and the electronic structure in details.     

[H3tren] and [H4tren] fluoride zirconates or tantalates

Four new [H₃tren]³⁺ or [H₄tren]⁴⁺ fluoride zirconates and two new [H₃tren]³⁺ fluoride tantalates are evidenced in the (ZrF₄ or Ta₂O₅)-tren-HF_aq.-ethanol systems at 190 °C: the structurally related phases [H₄tren]·(Zr₂F₁₂)·H₂O and α-[H₄tren]·(Zr₂F₁₂) (P2₁2₁2₁), β-[H₄tren]·(Zr₂F₁₂) (P2₁/c), [H₃tren]₄·(ZrF₈)₃·4H₂O (I23), β-[H₃tren]₂·(Ta₃O₂F₁₆)·(F) (R32) and its monoclinic distortion α-[H₃tren]₂·(Ta₃O₂F₁₆)·(F) (C2/m). α and β-[H₄tren]·(Zr₂F₁₂) and [H₄tren]·(Zr₂F₁₂)·H₂O are built up from (Zr₂F₁₂) dimers of edge sharing ZrF₇ polyhedra while isolated ZrF₈ dodecahedra are found in [H₃tren]₄·(ZrF₈)₃·4H₂O. Linear (Ta₃O₂F₁₆) trimers build α and β-[H₃tren]₂·(Ta₃O₂F₁₆)·(F); they consist of two (TaOF₆) pentagonal bipyramids that are linked to two opposite oxygen atoms of one central (TaO₂F₄) octahedron. A disorder affects the equatorial fluorine atoms of the trimers and eventually carbon or nitrogen atoms of [H₃tren]³⁺ cations.     

A large series of isotypic Mo(V) diphosphates with a tunnel structure: From A(MoO)10(P2O7)8 with A=Ba, Sr, Ca, Cd, Pb to A(MoO)5(P2O7)4 with A=Ag, Li, Na, K

The single crystal structure of a series of nine isotypic Mo(V) diphosphates was determined from crystals with composition A²⁺(MoO)₁₀(P₂O₇)₈ (A=Ba, Sr, Ca, Cd, Pb) and A⁺(MoO)₅(P₂O₇)₄ (A=Ag, Li, Na, K). The structure of those phosphates, built up of corner sharing MoO₆ octahedra, MoO₅ tetragonal pyramids and P₂O₇ diphosphates groups, forms eight-sided tunnels as described by Lii et al. for A=Ag. New features are evidenced: (1) existence of two orientations, up and down along b for the MoO₅ pyramids; (2) maximum insertion rate of the divalent cations which is twice less than that of the univalent cations; (3) different behavior of the series “Pb, Sr, Ba, Li, Na, K” which exhibits only one kind of site for the inserted cation, compared to the “Cd, Ca, Ag” series for which two kinds of sites are observed; (4) off-centering of the A-site cations with respect to the tunnel axis; and (5) unusually high thermal factors along the tunnel axis, but absence of ionic conductivity.     

Synthesis and characterization of n=5, 6 members of the La4Srn−4TinO3n+2 series with layered structure based upon perovskite

Layered compounds have been synthesized and structurally characterized for the n=5 and 6 members of the perovskite-related family La₄Sr_n−4Ti_nO_3n+2 by combining X-ray diffraction and transmission electron microscopy. Their structure can be regarded as comprising [(La,Sr)₅Ti₅O₁₇] and [(La,Sr)₆Ti₆O₂₀] perovskite blocks joined by crystallographic shears along the a-axis, with consecutive blocks shifted by 1/2 [100]_p. The n=5 member is similar to the previously reported n=5 member of other A_nB_nO_3n+2-related series. The n=6 member, which has only been briefly reported in other systems previously, is also a well-behaved member of this A_nB_nO_3n+2 series.     

Synthesis, structure of [H3dien]·(MF6)·H2O (M=Cr, Fe) and Fe Mössbauer study of [H3dien]·(FeF6)·H2O

Single crystals of [H₃dien]·(FeF₆)·H₂O (I) and [H₃dien]·(CrF₆)·H₂O (II) are obtained by solvothermal synthesis under microwave heating. I is orthorhombic (Pna2₁) with a=11.530(2) Å, b=6.6446(8) Å, c=13.787(3) Å, V=1056.3(2) Å³ and Z=4. II is monoclinic (P2₁/c) with a=13.706(1) Å, b=6.7606(6) Å, c=11.3181(9) Å, β=99.38(1)°, V=1034.7(1) Å³ and Z=4. The structure determinations, performed from single crystal X-ray diffraction data, lead to the R₁/wR₂ reliability factors 0.028/0.066 for I and 0.035/0.102 for II. The structures of I and II are built up from isolated FeF₆ or CrF₆ octahedra, water molecules and triprotonated amines. In both structures, each octahedron is connected by hydrogen bonds to six organic cations and two water molecules. The iron-based compound is also characterized by ⁵⁷Fe Mössbauer spectrometry: the hyperfine structure confirms the presence of Fe³⁺ in octahedral coordination and reveals the existence of paramagnetic spin fluctuations.     

Synthesis of Li2PtH6 using high pressure: Completion of the homologous series A2PtH6 (A=alkali metal)

Li₂PtH₆, the missing member of the complex transition metal hydride series A₂PtH₆ (A=alkali metal), was prepared by reacting mixtures of LiH and Pt in the presence of BH₃NH₃ as hydrogen source at pressures above 8 GPa. According to powder X-ray diffraction analysis, Li₂PtH₆ is isostructural to its heavier homologues and crystallizes in the cubic K₂PtCl₆ structure (space group Fm3¯m, a=6.7681(3), Z=4). However, PtH₆²⁻ octahedral complexes in Li₂PtH₆ approach each other closely and its structure may likewise be regarded as a defective perovskite structure where half of the octahedrally coordinated atoms (cations) are missing. The IR spectrum of Li₂PtH₆ reveals the Pt-H T_1u stretch and bend at 1840 and 889 cm⁻¹, respectively.