On the Formation of Intermetalloid Clusters: Titanocene(III)diammin as a Versatile Reactant Toward Nonastannide Zintl Clusters

The reactivity of TiCp₂Cl₂ (d⁰) towards Zintl clusters was studied in liquid ammonia (Cp=cyclopentadienyl). Reduction of Ti^IVCp₂Cl₂ and ligand exchange led to the formation of [Ti^IIICp₂(NH₃)₂]⁺, also obtainable by recrystallization of [CpTi^IIICl]₂. Upon reaction with [K₄Sn₉], ligand exchange leads to [TiCp₂(η¹‐Sn₉)(NH₃)]^3?. A small variation of the stoichiometry led to the formation of [Ti(η⁴‐Sn₈)Cp]^3?, which cocrystallizes with [TiCp₂(NH₃)₂]⁺ and [TiCp₂(η¹‐Sn₉)(NH₃)]^3?. Finally, the large intermetalloid cluster anion [Ti₄Sn₁₅Cp₅]^n? (n=4 or 5) was obtained from the reaction of K₁₂Sn₁₇ and TiCp₂Cl₂ in liquid ammonia. The isolation of three side products, [K([18]crown‐6)]Cp, [K([18]crown‐6)]Cp(NH₃), and [K([2.2]crypt)]Cp, suggests a stepwise elimination of the Cl^? and Cp^? ligands from TiCp₂Cl₂ and thus gives a hint to the mechanism of the product formation in which [Ti(η⁴⁺²‐Sn₈)Cp]^3? has a key role.     

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.     

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.     

Cyclic Tribismuthide as a Piano Stool Complex Ligand – Synthesis and Crystal Structure of (η3‐Bi3)M(CO)33– (M = Cr,Mo)

The reactions between K₅Bi₄, [(C₆H₆)Cr(CO)₃] or [(C₇H₈)Mo(CO)₃], and [2.2.2]crypt in liquid ammonia yielded the compounds [K([2.2.2]crypt)]₃(η³‐Bi₃)M(CO)₃ · 10NH₃ (M = Cr, Mo), which crystallize isostructurally in P2₁/n. Both contain an 18 valence electron piano‐stool complex with a η³‐coordinated Bi₃‐ring ligand. The Bi–Bi distances range from 2.9560(5) to 2.9867(3) Å and are slightly shorter than known Bi–Bi single bonds but longer than Bi–Bi double bonds. The newly found compounds complete the family of similar complexes with E₃‐ring ligands (E = P‐Bi).     

[Bi4]6– – The Zintl Anion with the Highest Charge per Atom Obtained from Solution

From the dark‐purple solution of the Zintl phase KBi in liquid ammonia dark‐blue crystals of the ammonia solvate K₆[Bi₄](NH₃)₈ were obtained. In contrast to known Bi_n polyanions the chemical bond in the anion [Bi₄]^6– is in accordance with the (8‐N) rule featuring solely Bi–Bi single bonds. [Bi₄]^6– is a butane‐analog valence compound, and with 6 negative charges per 4 atoms it is the anion with the highest known charge per atom obtained from solution. The planarity of the trans‐[Bi₄]^6– unit hints at π orbital contributions of the bismuth atoms. The corresponding reactions of the phases K₅Bi₄ and K₃Bi₂ in liquid ammonia in the presence of [2.2.2]crypt(4, 7, 13, 16, 21, 24‐hexaoxa‐1, 10‐diazabicyclo‐[8.8.8]hexacosane) lead to the salt [K([2.2.2]crypt)]₂[Bi₂](NH₃)₄ with the known electron‐deficient [Bi₂]^2– polyanion and a Bi=Bi double bond.     

Gold(I) and Silver(I) Complexes of Diphosphacyclobutadiene Cobaltate Sandwich Anions

The synthesis and structural characterization of the first coordination compounds of bis(diphosphacyclobutadiene) cobaltate anions [M(P₂C₂R₂)₂]^? is described. Reactions of the new potassium salts [K(thf)₃{Co(η⁴‐P₂C₂tPent₂)₂}] ( 1 ) and [K(thf)₄{Co(η⁴‐P₂C₂Ad₂)₂}] ( 2 ) with [AuCl(tht)] (tht=tetrahydrothiophene), [AuCl(PPh₃)] and Ag[SbF₆] afforded the complexes [Au{Co(P₂C₂tPent₂)₂}(PMe₃)₂] ( 3 ), [Au{Co(P₂C₂Ad₂)₂}]_x ( 4 ), [Ag{Co(P₂C₂Ad₂)₂}]_x ( 5 ), [Au(PMe₃)₄][Au{Co(P₂C₂Ad₂)₂}₂] ( 6 ), [K([18]crown‐6)(thf)₂][Au{Co(P₂C₂Ad₂)₂}₂] ( 7 ), and [K([18]crown‐6)(thf)₂][M{Co(P₂C₂Ad₂)₂}₂] ( 8 : M=Au 9 : M=Ag) in moderate yields. The molecular structures of 2 and 3 , and 6 – 9 were elucidated by X‐ray crystallography. Complexes 4 – 9 were thoroughly characterized by ³¹P and ¹³C solid state NMR spectroscopy. The complexes [Au{Co(P₂C₂Ad₂)₂}]_x ( 4 ) and [Ag{Co(P₂C₂Ad₂)₂}]_x ( 5 ) exist as coordination polymers in the solid state. The linking mode between the monomeric units in the polymers is deduced. The soluble complexes 1 – 3 , 6 , and 7 were studied by multinuclear ¹H‐, ³¹P{¹H}‐, and ¹³C{¹H} NMR spectroscopy in solution. Variable temperature NMR measurements of 3 and 6 in deuterated THF reveal the formation of equilibria between the ionic species [Au(PMe₃)₄]⁺, [Au(PMe₃)₂]⁺, [Co(P₂C₂R₂)₂]^?, and [Au{Co(P₂C₂R₂)₂}₂]^? (R=tPent and Ad).     

[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.     

Copper(I) and Silver(I) Bis(trifluoromethanesulfonyl)imide and Their Interaction with an Arene,Diverse Olefins,and an NTf2−‐Based Ionic Liquid

The chemistry of coinage metal bis(triflyl)imides of technological interest, CuNTf₂ and AgNTf₂, their synthesis and complexes with excess of comparatively weakly coordinating NTf₂^? as well as with ether, olefins, and the arene mesitylene are described. The existence of the solvent‐free pure phase [CuNTf₂]_∞ has not been evidenced so far. Contrary to the literature, in which the preparation of [CuNTf₂]_∞ is supposed to be carried out by reacting mesityl copper, [Cu(Mes)]₅, and HNTf₂, we found that in fact this reaction leads reproducibly to the interesting copper diarene sandwich complex [Cu(η³‐MesH)₂][Cu(NTf₂)₂] ( 1 ) (MesH=1,3,5‐trimethylbenzene). The unexpectedly stable molecular etherate [Cu(Et₂O)(NTf₂)] ( 2 ) turned out to be the best precursor for CuNTf₂ having only an inert and easily exchangeable solvent ligand. The coordination mode of NTf₂^? in 1 and 2 as well as in the hitherto unknown crystalline phase of [AgNTf₂]_∞ ( 3 ) is described. The complex formation, which takes place when dissolving 2 or 3 in the room temperature ionic liquid (RTIL) [emim]NTf₂ ([emim]⁺=1‐ethyl‐3‐methylimidazolium), has been studied. Furthermore, the reaction of 1 – 3 towards the diolefins 1,5‐cyclooctadiene (COD), 2,5‐norbornadiene (NBD) and isoprene (2‐methylbuta‐1,3‐diene) and towards ethylene has been investigated. The products 4 – 13 of these conversions have been isolated and fully characterized by NMR‐ and IR spectroscopies, mass spectrometry, and elemental‐ and XRD analyses. The potential of [Cu(η³‐MesH)₂][Cu(NTf₂)₂] ( 1 ), [Cu(Et₂O)(NTf₂)] ( 2 ) and [AgNTf₂]_∞ ( 3 ) as well as of [emim][M(NTf₂)₂] (M=Cu 4 , Ag 5 ) as chemisorbers for ethylene was studied by NMR spectroscopy.     

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.     

Syntheses and Crystal Structures of Ammoniates with the Phenyl‐Substituted Polytin Anions Sn2Ph$\rm{_{\bf 4}^{{\bf 2} - } }$, cyclo‐Sn4Ph$\rm{_{\bf 4}^{{\bf 4} - } }$, and Sn6Ph$\rm{_{{\bf 12}}^{{\bf 2} - } }$

The reaction of diphenyltin dichloride with the binary Zintl phase K₄Sn₉ in the presence of excess lithium and 18‐crown‐6 in liquid ammonia led to the ammoniate [K(18‐crown‐6)(NH₃)₂]₂Sn₂Ph₄ ( 1 ). The analogous reaction with K₄Ge₉ and potassium in the absence of further alkali metal ligands resulted in the compound [K₂(NH₃)₁₂]Sn₆Ph₁₂ ? 4 NH₃ ( 3 ). Cs₆[Sn₄Ph₄](NH₂)₂ ? 8 NH₃ ( 2 ) was prepared by reacting diphenyltin dichloride with a surplus of caesium in liquid ammonia. The low‐temperature single‐crystal structure determinations show all compounds to contain phenyl‐substituted polyanions of tin. Compound 1 is built from Sn₂Ph anions consisting of Sn dumbbells with two Ph substituents at each Sn‐atom. Compound 2 contains cyclo‐Sn₄Ph anions formed by a four‐membered tin ring in butterfly conformation with one Ph substituent at each Sn‐atom in an (all‐trans)‐configuration. Sn₆Ph in 3 is a zig‐zag Sn₆ chain with two substituents at each of the Sn‐atoms. Both 1 and 3 have molecular counter cations, in the latter case the unprecedented dinuclear potassiumammine complex [K₂(NH₃)₁₂]²⁺ is observed. Compound 2 shows a complicated three‐dimensional network of Cs? Sn interactions.     

{μ‐PbSe}: A Heavy CO Homologue as an Unexpected Ligand

Reactions of [K(18‐crown‐6)]₂[Pb₂Se₃] and [K([2.2.2]crypt)]₂[Pb₂Se₃] with [Rh(PPh₃)₃Cl] in en (ethane‐1,2‐diamine) afforded ionic compounds with [Rh₃(PPh₃)₆(μ₃‐Se)₂]^? and [Rh₃(CN)₂(PPh₃)₄(μ₃‐Se)₂(μ‐PbSe)]^3? anions, respectively. The latter contains a PbSe ligand, a rather uncommon homologue of CO that acts as a μ‐bridge between two Rh atoms. Quantum chemical calculations yield a significantly higher bond energy for PbSe than for CO, since the size of the ligand orbitals better matches the comparably rigid Rh‐Se‐Rh angles and the resulting Rh???Rh distance. To rationalize the bent coordination of the ligand, orbitals with significant ligand contributions and their dependence on the bonding angle were investigated in detail.     

Formation of [Bi11]3−, A Homoatomic,Polycyclic Bismuth Polyanion,by Pyridine‐Assisted Decomposition of [GaBi3]2−

Until now, polycyclic bismuth polyanions have not been known—thus discriminating bismuth from its lighter congeners. However, the synthesis of [K([2.2.2]crypt)]₃(Bi₁₁)?2 py?tol, allows us to present the first structurally characterized homoatomic, polycyclic bismuth polyanion, which exhibits the [P₁₁]^3? “ufosan” structure. It was obtained upon treatment of [K([2.2.2]crypt)]₂(GaBi₃)?en with the solvent pyridine. The binary Zintl anion [GaBi₃]^2? decomposes under oxidative coupling of pyridine molecules and release of H₂ to form the title compound. The unprecedented reaction, its products and by‐products were investigated by means of spectroscopy, spectrometry, and DFT studies. All findings reveal the specific reaction conditions to be crucial for the formation of the [Bi₁₁]^3? ion—and indicate the possibility of the generation and isolation of further, large bismuth polyanions.     

Coordination Behavior of a D‐Penicillaminato Aurate(I) Metalloligand Toward Coblat(III) Centers

Treatment of (NH₄)[Au(D‐Hpen‐S)₂](D‐H₂pen = D‐penicillamine) with CoCl₂·6H₂O in an acetate buffer solution, followed by air oxidation, gave neutral Au^ICo^III and anionic Au^I₃Co^III₂ polynuclear complexes, [Au₃Co₃(D‐pen‐N,O,S)₆]([ 1 ]) and [Au₃Co₂(D‐pen‐N,S)₆]^3? ([ 2 ]^3?), which were separated by anion‐exchange column chromatography. Complexes [ 1 ] and [ 2 ]^3? each formed a single isomer, and their structures were determined by single‐crystal X‐ray crystallography. In [ 1 ], each of three [Au(D‐pen‐S)₂]^3?metalloligands coordinates to two Co^III ions in a bis‐tridentate‐N,O,S mode to form a cyclic Au^I₃Co^III₃ hexanuclear structure, in which three [Co(D‐pen‐N,O,S)₂]^? octahedral units and six bridging S atoms adopt trans(O) geometrical and R chiral configurations, respectively. In [ 2 ]^3?, each of three [Au(D‐pen‐S)₂]^3? metalloligands coordinates to two Co^III ions in a bis‐bidentate‐N,S mode to form a Au^I₃Co^III₂ pentanuclear structure, in which two [Co(D‐pen‐N,S)₃]^3? units and six bridging S atoms adopt ∧ and R chiral configurations, respectively.     

Studies on the Reactivity of [Ge9]4− towards [Fe(cot)(CO)3]: Synthesis and Characterization of [Ge8Fe(CO)3]3− and of the Anionic Organometallic Species [Fe(cot)(CO)3]−

Reaction of cyclooctatetraene (COT) iron(II) tricarbonyl, [Fe(cot)(CO)₃], with one equivalent of K₄Ge₉ in ethylenediamine (en) yielded the cluster anion [Ge₈Fe(CO)₃]^3? which was crystallographically‐characterized as a [K(2,2,2‐crypt)]⁺ salt in [K(2,2,2‐crypt)]₃[Ge₈Fe(CO)₃]. The chemically‐reduced organometallic species [Fe(η³‐C₈H₈)(CO)₃]^? was also isolated as a side‐product from this reaction as [K(2,2,2‐crypt)][Fe(η³‐C₈H₈)(CO)₃]. Both species were further characterized by EPR and IR spectroscopy and electrospray mass spectrometry. The [Ge₈Fe(CO)₃]^3? cluster anion represents an unprecedented functionalized germanium Zintl anion in which the nine‐atom precursor cluster has lost a vertex, which has been replaced by a transition‐metal moiety.     

Solution Synthesis,Structure, and CO2 Reduction Reactivity of a Scandium(II) Complex, {Sc[N(SiMe3)2]3}−

The first crystallographically characterizable complex of Sc²⁺, [Sc(NR₂)₃]⁻ (R=SiMe₃), has been obtained by LnA₃/M reactions (Ln=rare earth metal; A=anionic ligand; M=alkali metal) involving reduction of Sc(NR₂)₃ with K in the presence of 2.2.2‐cryptand (crypt) and 18‐crown‐6 (18‐c‐6) and with Cs in the presence of crypt. Dark maroon [K(crypt)]⁺, [K(18‐c‐6)]⁺, and [Cs(crypt)]⁺ salts of the [Sc(NR₂)₃]⁻ anion are formed, respectively. The formation of this oxidation state of Sc is also indicated by the eight‐line EPR spectra arising from the I =7/2 ⁴⁵Sc nucleus. The Sc(NR₂)₃ reduction differs from Ln(NR₂)₃ reactions (Ln=Y and lanthanides) in that it occurs under N₂ without formation of isolable reduced dinitrogen species. [K(18‐c‐6)][Sc(NR₂)₃] reacts with CO₂ to produce an oxalate complex, {K₂(18‐c‐6)₃}{[(R₂N)₃Sc]₂(μ‐C₂O₄‐κ ¹O:κ ¹O′′)}, and a CO₂⁻ radical anion complex, [(R₂N)₃Sc(μ‐OCO‐κ ¹O:κ ¹O′)K(18‐c‐6)]_n .     

Ionic‐Radius‐Driven Selection of the Main‐Group‐Metal Cage for Intermetalloid Clusters [Ln@PbxBi14−x]q− and [Ln@PbyBi13−y]q− (x/q=7/4, 6/3; y/q=4/4, 3/3)

Reactions of the binary, pseudo‐homoatomic Zintl anion (Pb₂Bi₂)^2? with Ln(C₅Me₄H)₃ (Ln=La, Ce, Nd, Gd, Sm, Tb) in the presence of [2.2.2]crypt in ethane‐1,2‐diamine/toluene yielded ten [K([2.2.2]crypt)]⁺ salts of lanthanide‐doped semimetal clusters with 13 or 14 surface atoms. Single‐crystal X‐ray diffraction and energy‐dispersive X‐ray spectroscopy indicated the presence of the anions [Ln@Pb₆Bi₈]^3?, [Ln@Pb₃Bi₁₀]^3?, [Ln@Pb₇Bi₇]^4?, or [Ln@Pb₄Bi₉]^4? in single or double salts; the latter showed various ratios of the components in the solid state. The anions are the first ternary intermetalloid clusters comprising only elements of the sixth period of the periodic table, namely, Pb, Bi and lanthanides. This study, which was complemented by ESI mass spectrometry and ¹³⁹La NMR spectroscopy in solution, rationalizes a continuous development of the ratio of 13:14‐atom cages with the ionic radius of the embedded Ln³⁺ ion, which seems to select the most suitable cage type. Quantum chemical investigations helped to analyze this situation in more detail and to explain the observed subtle influence of the atomic radii. Magnetic measurements confirmed that the embedded Ln³⁺ ions keep their expected paramagnetic or diamagnetic nature.     

Ligand Effects on the Electronic Structure of Heteroleptic Antimony‐Centered Radicals

We report on the structures of three unprecedented heteroleptic Sb‐centered radicals [L(Cl)Ga](R)Sb^. ( 2‐R , R=B[N(Dip)CH]₂ 2‐B , 2,6‐Mes₂C₆H₃ 2‐C , N(SiMe₃)Dip 2‐N ) stabilized by one electropositive metal fragment [L(Cl)Ga] (L=HC[C(Me)N(Dip)]₂, Dip=2,6‐i‐Pr₂C₆H₃) and one bulky B‐ ( 2‐B ), C‐ ( 2‐C ), or N‐based ( 2‐N ) substituent. Compounds 2‐R are predominantly metal‐centered radicals. Their electronic properties are largely influenced by the electronic nature of the ligands R, and significant delocalization of unpaired‐spin density onto the ligands was observed in 2‐B and 2‐N . Cyclic voltammetry (CV) studies showed that 2‐B undergoes a quasi‐reversible one‐electron reduction, which was confirmed by the synthesis of [K([2.2.2]crypt)][L(Cl)GaSbB[N(Dip)CH]₂] ([K([2.2.2]crypt)][ 2‐B ]) containing the stibanyl anion [ 2‐B ]^?, which was shown to possess significant Sb?B multiple‐bonding character.     

Expanding the Chemistry of Molecular U2+ Complexes: Synthesis,Characterization, and Reactivity of the {[C5H3(SiMe3)2]3U}− Anion

The synthesis of new molecular complexes of U²⁺ has been pursued to make comparisons in structure, physical properties, and reactivity with the first U²⁺ complex, [K(2.2.2‐cryptand)][Cp′₃U], 1 (Cp′=C₅H₄SiMe₃). Reduction of Cp′′₃U [Cp′′=C₅H₃(SiMe₃)₂] with KC₈ in the presence of 2.2.2‐cryptand or 18‐crown‐6 generates [K(2.2.2‐cryptand)][Cp′′₃U], 2‐K(crypt) , or [K(18‐crown‐6)(THF)₂][Cp′′₃U], 2‐K(18c6) , respectively. The UV/Vis spectra of 2‐K and 1 are similar, and they are much more intense than those of U³⁺ analogues. Variable temperature magnetic susceptibility data for 1 and 2‐K(crypt) reveal lower room temperature χ_MT values relative to the experimental values for the 5f³ U³⁺ precursors. Stability studies monitored by UV/Vis spectroscopy show that 2‐K(crypt) and 2‐K(18c6) have t_1/2 values of 20 and 15 h at room temperature, respectively, vs. 1.5 h for 1 . Complex 2‐K(18c6) reacts with H₂ or PhSiH₃ to form the uranium hydride, [K(18‐crown‐6)(THF)₂][Cp′′₃UH], 3 . Complexes 1 and 2‐K(18c6) both reduce cyclooctatetraene to form uranocene, (C₈H₈)₂U, as well as the U³⁺ byproducts [K(2.2.2‐cryptand)][Cp′₄U], 4 , and Cp′′₃U, respectively.     

Kristallstruktur von (NH4)3SnF7: Ein Doppelsalz gemäß (NH4)3[SnF6]F und kein (NH4)4SnF8

Crystal Structure of (NH₄)₃SnF₇: A Double Salt According to (NH₄)₃[SnF₆]F and not (NH₄)₄SnF₈ (NH₄)₃SnF₇ is obtained as colourless single crystals from the reaction of NH₄HF₂ with tin powder at 300°C. The crystal structure (cubic, Pm3m, Z = 1, a = 602.5(1) pm at 293 K; a = 598.0(1) pm at 100 K) contains [SnF₆]^2? octahedra and lonesome F^? ions surrounded by NH₄⁺ cations only; it may be considered as a derivative of the Cu₃Au-type of structure according to Cu₃[Au]□ ?(NH₄)₃[SnF₆]F. The F^? ions of the [SnF₆]^2? octahedra with their Sn⁴⁺ centre in the origin of the unit cell at m3m are disordered in different ways at 293 and 100 K, respectively.     

Solution Synthesis,Structure, and CO2 Reduction Reactivity of a Scandium(II) Complex, {Sc[N(SiMe3)2]3}−

The first crystallographically characterizable complex of Sc²⁺, [Sc(NR₂)₃]⁻ (R=SiMe₃), has been obtained by LnA₃/M reactions (Ln=rare earth metal; A=anionic ligand; M=alkali metal) involving reduction of Sc(NR₂)₃ with K in the presence of 2.2.2‐cryptand (crypt) and 18‐crown‐6 (18‐c‐6) and with Cs in the presence of crypt. Dark maroon [K(crypt)]⁺, [K(18‐c‐6)]⁺, and [Cs(crypt)]⁺ salts of the [Sc(NR₂)₃]⁻ anion are formed, respectively. The formation of this oxidation state of Sc is also indicated by the eight‐line EPR spectra arising from the I =7/2 ⁴⁵Sc nucleus. The Sc(NR₂)₃ reduction differs from Ln(NR₂)₃ reactions (Ln=Y and lanthanides) in that it occurs under N₂ without formation of isolable reduced dinitrogen species. [K(18‐c‐6)][Sc(NR₂)₃] reacts with CO₂ to produce an oxalate complex, {K₂(18‐c‐6)₃}{[(R₂N)₃Sc]₂(μ‐C₂O₄‐κ ¹O:κ ¹O′′)}, and a CO₂⁻ radical anion complex, [(R₂N)₃Sc(μ‐OCO‐κ ¹O:κ ¹O′)K(18‐c‐6)]_n .