The Neat Ternary Solid K5−xCo1−xSn9 with Endohedral [Co@Sn9]5− Cluster Units: A Precursor for Soluble Intermetalloid [Co2@Sn17]5− Clusters

A new type of Zintl phase is presented that contains endohedrally filled clusters and that allows for the formation of intermetalloid clusters in solution by a one‐step synthesis. The intermetallic compound K_5?xCo_1?xSn₉ was obtained by the reaction of a preformed Co? Sn alloy with potassium and tin at high temperatures. The diamagnetic saltlike ternary phase contains discrete [Co@Sn₉]^5? clusters that are separated by K⁺ ions. The intermetallic compound K_5?xCo_1?xSn₉ readily and incongruently dissolves in ethylenediamine and in the presence of 4,7,13,16,21,24‐hexaoxa‐1,10‐diazabicyclo[8.8.8]hexacosane (2.2.2‐crypt), thereby leading to the formation of crystalline [K([2.2.2]crypt)]₅[Co₂Sn₁₇]. The novel polyanion [Co₂Sn₁₇]^5? contains two Co‐filled Sn₉ clusters that share one vertex. Both compounds were characterized by single‐crystal X‐ray structure analysis. The diamagnetism of K_5?xCo_1?xSn₉ and the paramagnetism of [K([2.2.2]crypt)]₅[Co₂Sn₁₇] have been confirmed by superconducting quantum interference device (SQUID) and EPR measurements, respectively. Quantum chemical calculations reveal an endohedral Co^1? atom in an [Sn₉]^4? nido cluster for [Co@Sn₉]^5? and confirm the stability of the paramagnetic [Co₂Sn₁₇]^5? unit.     

Metallocages for Metal Anions: Highly Charged [Co@Ge9]5− and [Ru@Sn9]6− Clusters Featuring Spherically Encapsulated Co1− and Ru2− Anions

Endohedral clusters count as molecular models for intermetallic compounds—a class of compounds in which bonding principles are scarcely understood. Herein we report soluble cluster anions with the highest charges on a single cluster to date. The clusters reflect the close analogy between intermetalloid clusters and corresponding coordination polyhedra in intermetallic compounds. We now establish Raman spectroscopy as a reliable probe to assign for the first time the presence of discrete, endohedrally filled clusters in intermetallic phases. The ternary precursor alloys with nominal compositions “K₅Co_1.2Ge₉” and “K₄Ru₃Sn₇” exhibit characteristic bonding modes originating from metal atoms in the center of polyhedral clusters, thus revealing that filled clusters are present in these alloys. We report also on the structural characterization of [Co@Ge₉]^5? ( 1a ) and [Ru@Sn₉]^6? ( 2a ) obtained from solutions of the respective alloys.     

Binary alkali metal compounds with the zintl anions [Ge9]4− and [Sn9]4−

The binary germanides M₁₂Ge₁₇ and M₄Ge₉ (M ? Na, K, Rb, Cs) and the stannides M₁₂Sn₁₇ and M₄Sn₉ (M ? K, Rb, Cs) were identified by a combination of direct synthesis, thermogravimetric analysis, vibrational spectroscopy, X-ray powder data and single crystal structure analysis. The M₁₂E₁₇ phases contain the cluster anions [E₉]^4? and [E₄]^4? in the ratio 1:2, forming a hierarchical structure with the cluster anions at the atomic positions of the hexagonal Laves phase MgZn₂. Like the M₄E₄ phases, the M₄Ge₉ compounds are hierarchical derivatives of the cubic Cr₃Si structure but with [Ge₉]^4? anions. The thermogravimetric analyses give strong evidence for the existence of at least one more phase with [E₉]^4? and [E₄]^4? clusters and of the clathrate phases M₆E₁₃₆ in addition to the well-known M₈E₄₄□₂ chlathrates.     

[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 [E₉]^4? (E = Si-Pb) and intermetalloid clusters [M@E₉]^q?, the reactions of the Zintl anions [Sn₉]^4? and [Ni@Sn₉]^4? with the CdMes₂ (Mes = Mesitylene) in the presence of 2.2.2-crypt were carried out. Two new compounds [K(2.2.2-crypt)]₆[(Sn₉)Cd(Sn₉)]·en (1) and [K(2.2.2-crypt)]₆[(Ni@Sn₉)Cd(Ni@Sn₉)]·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 [Sn₉]^4? or [Ni@Sn₉]^4? subunits bridged by Cd ion in an η³:η³ coordination mode. Quantum chemical calculations reveal the relationships between the geometries and electronic structures of clusters 2a, [Ni₃Ge₁₈]^4? and [Cu₄@Sn₁₈]^4?. Further electron localization technique (AdNDP method) was performed to explain chemical bonding patterns of 1a.     

Extracting [Pd@Sn9]4– and [Rh@Pb9]4– Clusters from their Binary Alloys Using “Metal Scissors”

The search for novel ternary intermetallic compounds with specific structures is still a challenge. We found that the two-step synthesis giving a typical alloy in the first step followed by the reaction of this alloy with alkali metals is a promising route. The intermetallic compounds K₁₂Pd_0.47Sn₁₇ and K₄RhPb₉ were synthesized by high-temperature reactions of preformed Pd-Sn and Rh-Pb alloys with K acting as “metal scissors” and were characterized by means of single crystal and powder X-ray diffractometry. The salt-like ternary phases K₁₂Pd_0.47Sn₁₇ and K₄RhPb₉ contain novel endohedrally filled intermetalloid clusters [Pd@Sn₉]^4– and [Rh@Pb₉]^4–, respectively. The crystal packing of the products corresponds to filled variants of the binary Zintl phases K₁₂Sn₁₇ and K₄Pb₉, respectively. The crystal structure of K₁₂Pd_0.47Sn₁₇ can be regarded as a hierarchical replacement variant of the hexagonal Laves phase MgZn₂, with [Pd@Sn₉]^4–/[Sn₉]^4– and [Sn₄]^4– on Mg and Zn positions, respectively, whereas the packing of [Rh@Pb₉]^4– clusters in K₄RhPb₉ is hcp. K₁₂Pd_0.47Sn₁₇ was characterized by Raman spectroscopy. For the first time Raman modes typical for endohedrally filled [Pd@Sn₉]^4– clusters are observed and in accordance with quantum-chemical calculations. In addition Raman spectroscopy shows also the presence of filled Pd@Sn₉ clusters in a phase of nominal composition “Na₁₂Pd₂Sn₁₇”. The results are discussed with respect to the volume increase due the incorporation of transition metal atoms.     

Step‐by‐Step Synthesis of the Endohedral Stannaspherene [Ir@Sn12]3− via the Capped Cluster Anion [Sn9Ir(cod)]3−

The endohedral stannaspherene cluster anion [Ir@Sn₁₂]^3? was synthesized in two steps. The reaction of K₄Sn₉ with [IrCl(cod)]₂ (cod: 1,5‐cyclooctadienyl) in ethylenediamine (en) solution first yielded the [K(2,2,2‐crypt)]⁺ salt (2,2,2‐crypt: 4,7,13,16,21,24‐hexaoxa‐1,10‐diazabicyclo[8.8.8]hexacosane) of the capped cluster anion [Sn₉Ir(cod)]^3?. Subsequently, crystals of this compound were dissolved in en, followed by the addition of triphenylphosphine or 1,2‐bis(diphenylphosphino)ethane and treatment at elevated temperatures. [Ir@Sn₁₂]^3? was obtained and characterized as the [K(2,2,2‐crypt)]⁺ salt. The isolation of [Sn₉Ir(cod)]^3? as an intermediate product establishes that the formation of the stannaspherene [Ir@Sn₁₂]^3? occurs through the oxidation of [Sn₉Ir(cod)]^3?. Among the structurally characterized tetrel cluster anions, [Ir@Sn₁₂]^3? is a unique example of a stannaspherene, and one of the rare spherical clusters encapsulating a metal atom that is not a member of Group 10. Single‐crystal structure determination shows that the novel Zintl ion cluster has nearly perfect icosahedral I_h point symmetry.     

K13CoSn17–x (x = 0.1): A New Ternary Phase Containing ­Cobalt Centered [Sn9] Cluster Synthesized via High‐Temperature Reaction

A new ternary potassium cobalt stannide, K₁₃CoSn_17–x (x = 0.1), was obtained by reacting the mixture of the corresponding pure elements at high temperature, and structurally characterized by single‐crystal X‐ray diffraction study. K₁₃CoSn_17–x (x = 0.1) crystallizes in the orthorhombic space group Pbca (No. 61) with a = 26.2799(7) Å, b = 24.1541(6) Å, c = 29.8839(6) Å, V = 18969.3(8) ų, and Z = 16. Its structure contains isolated [CoSn₉] monocapped square antiprism and [Sn₄] tetrahedron in the ratio 1:2, forming a hierarchical variant of Laves phase MgZn₂. The structural relation between the title compound with MgZn₂ as well as other binary stannides is also discussed.     

[SnBi3]5− —A Carbonate Analogue Comprising Exclusively Metal Atoms

The new [SnBi₃]⁵⁻ polyanion is obtained by the reaction of K₃Bi₂ with K₄Sn₉ or K₁₂Sn₁₇ in liquid ammonia. The anion is iso(valence)electronic with and structurally analogous to the carbonate ion. Despite the high negative charge of the anion, the Sn−Bi bond lengths range between single and double bonds. Quantum‐chemical calculations at a DFT‐PBE0/def2‐TZVPP/COSMO level of theory reveal that the partial double bond character between the heavy main‐group atoms Bi and Sn originates from a delocalized π‐electronic system. The structure of the anion is determined by single‐crystal X‐ray diffraction analyses of the compounds K₅[SnBi₃] 9 NH₃ ( 1 ) and K₉[K(18‐crown‐6)][SnBi₃]₂⋅15 NH₃ ( 2 ). The [SnBi₃]⁵⁻ unit is the first example of a carbonate‐like anion obtained from solution, and it consists exclusively of metal atoms and completes the series of metal analogues of CO and CO₂.     

Heterometallic Clusters [CuSn3S9]5− and [Cu6Sn6S20]10−: Solvothermal Synthesis and Characterization of 4f–3d Thiostannates

Two types of 4f–3d thiostannates with general formula [Hen]₂[Ln(en)₄(CuSn₃S₉)] ? 0.5 en ( Ln1 ; Ln=La, 1 ; Ce, 2 ) and [Hen]₄[Ln(en)₄]₂[Cu₆Sn₆S₂₀] ? 3 en ( Ln2 ; Ln=Nd, 3 ; Gd, 4 ; Er, 5 ) were prepared by reactions of Ln₂O₃, Cu, Sn, and S in ethylenediamine (en) under solvothermal conditions between 160 and 190 °C. However, reactions performed in the range from 120 to 140 °C resulted in crystallization of [Sn₂S₆]^4? compounds and CuS powder. In 1 and 2 , three SnS₄ tetrahedra and one CuS₃ triangle are joined by sharing sulfur atoms to form a novel [CuSn₃S₉]^5? cluster that coordinates to the Ln³⁺ ion of [Ln(en)₄]³⁺ (Ln=La, Ce) as a monodentate ligand. The [CuSn₃S₉]^5? unit is the first thio‐based heterometallic adamantane‐like cluster coordinating to a lanthanide center. In 3 – 5 , six SnS₄ tetrahedra and six CuS₃ triangles are connected by sharing common sulfur atoms to form the ternary [Cu₆Sn₆S₂₀]^10? cluster, in which a Cu₆ core is enclosed by two Sn₃S₁₀ fragments. The topological structure of the novel Cu₆ core can be regarded as two Cu₄ tetrahedra joined by a common edge. The Ln³⁺ ions in Ln1 and Ln2 are in nine‐ and eightfold coordination, respectively, which leads to the formation of the [CuSn₃S₉]^5? and [Cu₆Sn₆S₂₀]^10? clusters under identical synthetic conditions. The syntheses of Ln1 and Ln2 show the influence of the lanthanide contraction on the quaternary Ln/Cu/Sn/S system in ethylenediamine. Compounds 1 – 5 exhibit bandgaps in the range of 2.09–2.48 eV depending on the two different types of clusters in the compounds. Compounds 1 , 3 , and 4 lost their organic components in the temperature range of 110–350 °C by multistep processes.     

Pr10[Si10−xAlxO9+xN17−x]Cl with x ≈ 1 – an Oxonitridoaluminosilicate Chloride

The oxonitridoaluminosilicate chloride Pr₁₀[Si_10?xAl_xO_9+xN_17?x]Cl was obtained by the reaction of praseodymium metal, the respective chloride, AlN and Al(OH)₃ with “Si(NH)₂” in a radiofrequency furnace at temperatures around 1900 °C. The crystal structure was determined by single‐crystal X‐ray diffraction (Pbam, no. 55, Z = 2,a = 10.5973(8) Å, b = 11.1687(6) Å, c = 11.6179(7) Å, R1 = 0.0337). The sialon crystallizes isotypically to the oxonitridosilicate halides Ce₁₀[Si₁₀O₉N₁₇]Br, Nd₁₀[Si₁₀O₉N₁₇]Br and Nd₁₀[Si₁₀O₉N₁₇]Cl, which represent a new layered structure type. The structure refinement was performed utilizing an O/N‐distribution model according to Paulings rules, i.e. nitrogen was positioned on all bridging sites and mixed O/Noccupation was assumed on the terminal sites resulting in charge neutrality of the compounds. The Si and Al atoms were refined equally distributed on their three crystallographic sites, due to their poor distinguishability by X‐ray analysis. The tetrahedra layers of the structure consist of condensed [(Si,Al)N₂(O,N)₂] and [(Si,Al)N₃(O,N)] tetrahedra of Q² and Q³ type. The chemical composition of the compound was derived from electron probe micro analyses (EPMA).     

[Rb4Sn9] — A Low Dimensional Arrangement of Zintl Ions in [Rb(18‐crown‐6)]2Rb2[Sn9](en)1.5

The compound [Rb(18‐crown‐6)]₂Rb₂[Sn₉](en)_1.5 ( 1 ) was synthesized from an alloy of formal composition K₂Rb₂Sn₉ by dissolving in ethylenediamine (en) followed by the addition of 18‐crown‐6 and toluene. 1 crystallizes in the monoclinic space group P2₁/n with a = 10.557(2), b = 25.837(5), c = 20.855(4)Å, β = 102.39°, and Z = 4. The structure consists of [Sn₉]^4— cluster anions, which are connected via Rb atoms to infinite [Rb₄Sn₉] layers. The layers of binary composition are separated by the crown ether molecules. The crown ether molecules are bound by one side via the Rb atoms to the [Sn₉]^4— anions. The other side, which is turned away from the Rb atoms, shows only weak van der Waals interactions to the crown ether molecules of the next layer. Comparison with other compounds of similar composition shows, that the variation of the alkali metals and the complexing organic molecules leads to the low dimensional arrangement of the clusters.     

Reactivity of Liquid Ammonia Solutions of the Zintl Phase K12Sn17 towards Mesitylcopper(I) and Phosphinegold(I) Chloride

To gain more insight into the reactivity of intermetalloid clusters, the reactivity of the Zintl phase K₁₂Sn₁₇, which contains [Sn₄]^4? and [Sn₉]^4? cluster anions, was investigated. The reaction of K₁₂Sn₁₇ with gold(I) phosphine chloride yielded K₇[(η²‐Sn₄)Au(η²‐Sn₄)](NH₃)₁₆ ( 1 ) and K₁₇[(η²‐Sn₄)Au(η²‐Sn₄)]₂(NH₂)₃(NH₃)₅₂ ( 2 ), which both contain the anion [(Sn₄)Au(Sn₄)]^7? ( 1 a ) that consists of two [Sn₄]^4? tetrahedra linked through a central gold atom. Anion 1 a represents the first binary Au?Sn polyanion. From this reaction, the solvate structure [K([2.2.2]crypt)]₃K[Sn₉](NH₃)₁₈ ( 3 ; [2.2.2]crypt=4,7,13,16,21,24‐hexaoxa‐1,10‐diazabicyclo[8.8.8]hexacosane) was also obtained. In the analogous reaction of mesitylcopper with K₁₂Sn₁₇ in the presence of [18]crown‐6 in liquid ammonia, crystals of the composition [K([18]crown‐6)]₂[K([18]crown‐6)(MesH)(NH₃)][Cu@Sn₉](thf) ( 4 ) were isolated ([18]crown‐6=1,4,7,10,13,16‐hexaoxacyclooctadiene, MesH=mesitylene, thf=tetrahydrofuran) and featured a [Cu@Sn₉]^3? cluster. A similar reaction with [2.2.2]crypt as a sequestering agent led to the formation of crystals of [K[2.2.2]crypt][MesCuMes] ( 5 ). The cocrystallization of mesitylene in 4 and the presence of [MesCuMes]^? ( 5 a ) in 5 provides strong evidence that the migration of a bare Cu atom into an Sn₉ anion takes place through the release of a Mes^? anion from mesitylcopper, which either migrates to another mesitylcopper to form 5 a or is subsequently protonated to give MesH.     

Cluster Fusion: Face‐Fused Nine‐Atom Deltahedral Clusters in [Sn14Ni(CO)]4−

The title anion was synthesized by heating dimethylformamide (DMF) solution of the known Ni‐centered and Ni(CO)‐capped tin clusters [Ni@Sn₉Ni(CO)]^3?. The new anion represents the first example of face‐fused nine‐atom molecular clusters. The two clusters are identical elongated tricapped trigonal prisms of nido‐[Sn₈Ni(CO)]^6? with nickel at one of the capping positions. They are fused along a triangular face adjacent to a trigonal prismatic base and made of two Sn and one Ni atoms. The new anion is structurally characterized by single‐crystal X‐ray diffraction in the compound (K[222‐crypt])₄[Sn₁₄Ni(CO)]?DMF. Its presence in solution is corroborated by electrospray mass spectrometry.     

Origin and Location of Electrons and Protons during the Formation of Intermetalloid Clusters [Sm@Ga3−xH3−2xBi10+x]3− (x=0, 1)

Reaction of [GaBi₃]^2? with [Sm(C₅Me₄H)₃] yielded the first protonated ternary intermetalloid clusters [Sm@Ga_3?xH_3?2xBi_10+x]^3? ( 1 ; x=0,1). The presence of the Ga? H bonds and the transfer of electrons and protons during the formation of 1 were elucidated by a combination of experimental and quantum chemical methods, thereby rationalizing the role of the solvent ethane‐1,2‐diamine as a Brønsted acid. As an organic by‐product, we observed the previously unknown octamethylfulvene ( 2 ) upon C? C coupling of (C₅Me₄H)^?.     

Structural Variations in the Solid‐Solution Series LnxCa2−xAl[Al1+xSi1−xO7] with 0 ≤ x ≤ 1 and Ln = La,Eu, Er

Gehlenite, Ca₂Al[AlSiO₇], has melilite‐type structure with space group . It contains two topologically distinct positions coordinated tetrahedrally by oxygen. One is completely occupied by Al³⁺, whereas the other one contains Al³⁺ and Si⁴⁺. Normally, the Al³⁺ molar fraction in the second tetrahedrally coordinated position does not exceed x_Al = 0.5, i.e. the so‐called Loewenstein‐rule is obeyed. In this contribution the structural variations in the melilite‐type compounds of the compositions La_xCa_2?xAl[Al_1+xSi_1?xO₇], Eu_xCa_2?xAl[Al_1+xSi_1?xO₇] and Er_xCa_2?xAl[Al_1+xSi_1?xO₇] are discussed. All members of the solid solution except the end‐members violate Loewenstein's rule. Rietveld refinements against X‐ray powder diffraction patterns confirm that the compounds have space group , without changes in the Wyckoff‐positions of the ions compared to gehlenite.     

[Si4]4– and [Si9]4– Clusters Crystallized from Liquid Ammonia Solution – Synthesis and Characterization of K8[Si4][Si9]·(NH3)14.6

The extraction of the silicide K₁₂Si₁₇ with liquid ammonia in the presence of a sequestering agent and AuPPh₃Cl or Zn(Cp*)₂ led to crystals of the solvate compound K₈[Si₄][Si₉] · (NH₃)_14.6, which was characterized by single‐crystal X‐ray diffraction. It is the first compound with an isolated and ligand‐free [Si₄]^4– cluster obtained from solution. It also contains one [Si₉]^4– cluster per formula unit, whereas the precursor K₁₂Si₁₇ is built from [Si₄]^4– and [Si₉]^4– clusters with a 2:1 ratio.     

Charged Si9 Clusters in Neat Solids and the Detection of [H2Si9]2− in Solution: A Combined NMR,Raman, Mass Spectrometric,and Quantum Chemical Investigation

Polyanionic silicon clusters are provided by the Zintl phases K₄Si₄, comprising [Si₄]⁴⁻ units, and K₁₂Si₁₇, consisting of [Si₄]⁴⁻ and [Si₉]⁴⁻ clusters. A combination of solid‐state MAS‐NMR, solution NMR, and Raman spectroscopy, electrospray ionization mass spectrometry, and quantum‐chemical investigations was used to investigate four‐ and nine‐atomic silicon Zintl clusters in neat solids and solution. The results were compared to ²⁹Si isotope‐enriched samples. ²⁹Si‐MAS NMR and Raman shifts of the phase‐pure solids K₄Si₄ and K₁₂Si₁₇ were interpreted by quantum‐chemical calculations. Extraction of [Si₉]⁴⁻ clusters from K₁₂Si₁₇ with liquid ammonia/222crypt and their transfer to pyridine yields in a red solid containing Si₉ clusters. This compound was characterized by elemental and EDX analyses and ²⁹Si‐MAS NMR and Raman spectroscopy. Charged Si₉ clusters were detected by ²⁹Si NMR in solution. ²⁹Si and ¹H NMR spectra reveal the presence of the [H₂Si₉]²⁻ cluster anion in solution.     

Extraction of Ternary Alloys: Synthesis and Crystal Structure of [K([2.2.2]crypt)]Cs7[Sn9]2(en)3

The compound [K([2.2.2]crypt)]Cs₇[Sn₉]₂(en)₃ ( 1 ) was synthesized from an alloy of formal composition KCs₂Sn₉ by dissolving in ethylenediamine (en) followed by the addition of [2.2.2]crypt and toluene. 1 crystallizes in the orthorhombic space group Pcca with a = 45.38(2), b = 9.092(4), c = 18.459(8) Å, and Z = 4. The structure consists of Cs₇[Sn₉]₂ layers which contain [Sn₉]^4– anions and Cs⁺ cations. The layers are separated by [K([2.2.2]crypt)]⁺ units. In the intermetallic slab (Cs₇[Sn₉]₂)^– compares the arrangement of pairs of symmetry‐related [Sn₉]^4– anions with the dimer ([Ge₉]–[Ge₉])^6– in [K([2.2.2]crypt)]₂Cs₄([Ge₉]–[Ge₉]), in which the clusters are linked by a cluster‐exo bond. The shortest distance between atoms of such two clusters in 1 is 4.762 Å, e. g. there are no exo Sn‐Sn bonds. The [Sn₉]^4– anion has almost perfect C_4v‐symmetry.     

[Sn9HgSn9]6–: An Intermetalloid Zintl Ion with Two Sn9 Connected by Heteroatom

The title compound [K([2,2,2]crypt)]₁₂[Sn₉]₂[Sn₉HgSn₉] has been obtained by reaction of elemental mercury with the binary phase K₄Sn₉ in ethylenediamine after addition of [2,2,2]crypt and layering with toluene. The X‐ray single crystal analysis shows that the compound consists of two isolated Sn₉ clusters and two Sn₉ clusters connected by a mercury atom.     

Na12Ge17: A Compound with the Zintl Anions [Ge4]4— and [Ge9]4— — Synthesis,Crystal Structure,and Raman Spectrum

Na₁₂Ge₁₇ is prepared from the elements at 1025 K in sealed niobium ampoules. The crystal structure reinvestigation reveals a doubling of the unit cell (space group:P2₁/c; a = 22.117(3)Å, b = 12.803(3)Å, c = 41.557(6)Å, β = 91.31(2)°, Z = 16; Pearson code: mP464), furthermore, weak superstructure reflections indicate an even larger C‐centred monoclinic cell. The characteristic structural units are the isolated cluster anions [Ge₉]^4— and [Ge₄]^4— in ratio 1:2, respectively. The crystal structure represents a hierarchical cluster replacement structure of the hexagonal Laves phase MgZn₂ in which the Mg and Zn atoms are replaced by the Ge₉ and Ge₄ units, respectively. The Raman spectrum of Na₁₂Ge₁₇ exhibits the characteristic breathing modes of the constituent cluster anions at ν = 274 cm^—1 ([Ge₉]^4—) and ν = 222 cm^—1 ([Ge₄]^4—) which may be used for identification of these clusters in solid phases and in solutions. Raman spectra further prove that Na₁₂Ge₁₇ is partial soluble both in ethylenediamine and liquid ammonia. The solution and the solid extract contain solely [Ge₉]^4—. The remaining insoluble residue is Na₄Ge₄. By heating the solvate Na₄Ge₉(NH₃)_n releases NH₃ and decomposes irreversibly at 742 K, yielding Na₁₂Ge₁₇ and Ge.