Synthesis and crystal structures of Cd[AlCl4]2 and Cd2[AlCl4]2

Colorless single crystals of Cd[AlCl₄]₂ grow from the melt of CdCl₂ and AlCl₃ upon slow cooling from 250°C. The crystal structure [monoclinic, P1a1, Z = 2, a = 1288.7(2), b = 660.2(1), c = 705.1(1) pm, β = 92.89(1)º] may be derived from hexagonally closest packed layers of Cl^?. Octahedral and tetrahedral holes are filled with Cd²⁺ and Al³⁺ in a 1:2 ratio between all layers stacked in the [104] direction. Cd[GaCl₄]₂ and Cd[AlBr₄]₂ are isotypic. Reduction of Cd[AlCl₄]₂ with excess cadmium shot and slow cooling from 350°C yields plate-like very moisture-sensitive, colorless single crystals of Cd₂[AlCl₄]₂. The crystal structure [triclinic, C1 , Z = 2, a = 655.47(3), b = 1135.26(1), c = 935.23(6) pm, α = 89.70(2)º, β = 103.61(1)º, γ = 90.455(1)º] is built from slabs stacked in the [100] direction consisting of ethane-like [Cd₂Cl₆] units with a Cd? Cd distance of 256.1 pm sharing common vertices with [AlCl₄] tetrahedra.     

Rhenium Trichloride Dioxide,ReO2Cl3, Preparation and Reactions

A one step synthesis of ReO₂Cl₃ is reported. ReO₂Cl₃ reacts with [(C₂H₅)₄P]⁺Cl^?, forming [(C₂H₅)₄P]⁺[cis–ReO₂Cl₄]^?, a = 1257.0(2), b = 1026.8(2), c = 1277.9(2) pm, β = 106.659(3)°, P2₁/n. Also an unstable NO⁺[ReO₂Cl₄]^? can be obtained from NOCl and ReO₂Cl₃. With the Lewis acid GaCl₃ the zwitter ion [ReO₂Cl₂]⁺[GaCl₄]^? is formed. a = 1184.0(3), b = 829.2(2), c = 1100.8(2) pm, β = 112.98(1)°, P2₁/c.     

A Radical Tricationic Rhomboid Tetraborane(4) with Four‐Center,Five‐Electron Bonding

The red‐colored tetraborane(4) [B₄(hpp)₄]^3+. ( 3 ; hpp=1,3,4,6,7,8‐hexahydro‐2H‐pyrimido[1,2‐a]pyrimidinate) with a rhomboid B₄ skeleton stabilized by four N donors, was synthesized by the reaction of the strong hydride abstraction reagent [(acridine)BCl₂][AlCl₄] with the electron‐rich diborane(4) [HB(hpp)]₂ ( 1 ). The salt 3 [AlCl₄]₃ was structurally characterized and the presence of unpaired electrons proven by EPR measurements. The unprecedented radical tricationic 3 is distinguished by a high positive charge and boron atoms in a low oxidation state (less than two).     

On Silylated Oxonium and Sulfonium Ions and Their Interaction with Weakly Coordinating Borate Anions

Attempts have been made to prepare salts with the labile tris(trimethylsilyl)chalconium ions, [(Me₃Si)₃E]⁺ (E=O, S), by reacting [Me₃Si-H-SiMe₃][B(C₆F₅)₄] and Me₃Si[CB] (CB⁻=carborate=[CHB₁₁H₅Cl₆]⁻, [CHB₁₁Cl₁₁]⁻) with Me₃Si-E-SiMe₃. In the reaction of Me₃Si-O-SiMe₃ with [Me₃Si-H-SiMe₃][B(C₆F₅)₄], a ligand exchange was observed in the [Me₃Si-H-SiMe₃]⁺ cation leading to the surprising formation of the persilylated [(Me₃Si)₂(Me₂(H)Si)O]⁺ oxonium ion in a formal [Me₂(H)Si]⁺ instead of the desired [Me₃Si]⁺ transfer reaction. In contrast, the expected homoleptic persilylated [(Me₃Si)₃S]⁺ ion was formed and isolated as [B(C₆F₅)₄]⁻ and [CB]⁻ salt, when Me₃Si-S-SiMe₃ was treated with either [Me₃Si-H-SiMe₃][B(C₆F₅)₄] or Me₃Si[CB]. However, the addition of Me₃Si[CB] to Me₃Si-O-SiMe₃ unexpectedly led to the release of Me₄Si with simultaneous formation of a cyclic dioxonium dication of the type [Me₃Si-μO-SiMe₂]₂[CB]₂ in an anion-mediated reaction. DFT studies on structure, bonding and thermodynamics of the [(Me₃Si)₃E]⁺ and [(Me₃Si)₂(Me₂(H)Si)E]⁺ ion formation are presented as well as mechanistic investigations on the template-driven transformation of the [(Me₃Si)₃E]⁺ ion into a cyclic dichalconium dication [Me₃Si-μE-SiMe₂]₂²⁺.     

Room-Temperature Synthesis of the Bi5[GaCl4]3 Salt From Three Different Classes of Ionic Liquids

Following the development in the synthesis of subvalent cluster compounds, we report on the use of three different classes of room-temperature ionic liquids for the synthesis of the pentabismuth-tris(tetragallate) salt, Bi₅[GaCl₄]₃, characterized by X-ray diffraction. The Bi₅[GaCl₄]₃ salt was prepared by reduction of BiCl₃ using gallium metal in ionic liquid reaction media containing a strong Lewis acid, GaCl₃. The ionic liquids; trihexyltetradecyl phosphonium chloride [Th-Td-P⁺]Cl^?, 1-dodecyl-3-methylimidazolium chloride [Dod-Me-Im⁺]Cl^? and N-butyl-N-methylpyrrolidinium chloride [Bu-Me-Pyrr⁺]Cl^? from three of the main classes of ionic liquids were used in synthesis. Reactions using ionic liquids composed of the trihexyltetradecyl phosphonium cation [Th-Td-P⁺] and the anions; tetrafluoroborate [BF₄ ^?], bis(trifluoro-methyl sulfonyl) imide [(Tf)₂N^?] and hexafluorophosphate [PF₆ ^?] were also investigated.     

S5N5⊕[GaCl4]⊖ und S5N5⊕[Ga2Cl7]⊖. Synthesen,IR-Spektren und Kristallstrukturen

S₅N₅ ^⊕[GaCl₄]^? and S₅N₅ ^⊕[Ga₂Cl₇]^?. Synthesis, IR Spectra, and Crystal Structures . S₅N₅[GaCl₄] was obtained in high yields from gallium and trithiazyl chloride; depending on the solvent, different second products are formed: S₄N₄Cl[GaCl₄] in dichloromethane and S₃N₂Cl[GaCl₄] in carbon tetrachloride. These products can be separated due to their high solubility in CH₂Cl₂, S₅N₅[GaCl₄] being only slightly soluble. S₃N₂Cl[GaCl₄] can be converted to S₅N₅[GaCl₄] with additional (NSCl)₃. By the action of GaCl₃ on S₅N₅[GaCl₄], S₅N₅[Ga₂Cl₇] is formed. The IR spectra of the title compounds are reported; they differ considerably as well in number as in frequencies of the cation bands and show that the S₅N₅^⊕ ion has different structures depending on the anion. The crystal structures of both compounds were determined by X-ray diffraction. Crystal data: S₅N₅[GaCl₄], orthorhombic, a = 943.8, b = 1369.0, c = 2068.8 pm, space group Pnma, Z = 8 (1381 observed reflexions, R = 0.075); S₅N₅[Ga₂Cl₇], monoclinic, a = 847.5, b = 1298.2, c = 1654.0 pm, β = 93.51°, space group P2₁/n, Z = 4 (1359 observed reflexions, R = 0.065). S₅N₅[GaCl₄] is isotypic with S₅N₅[AlCl₄], showing a heartshaped S₅N₅^⊕ ion, but large ellipsoids of vibration suggest the presence of some kind of disorder (statical or dynamical). In S₅N₅[Ga₂Cl₇] the S₅N₅^⊕ has an azulene-like structure. In both cases the cations are planar, all S? N bond lengths being approximately equal.     

Cationic Functionalisation by Phosphenium Ion Insertion

The reaction of [Cp′′′Ni(η³-P₃)] ( 1 ) with in situ generated phosphenium ions [RR′P]⁺ yields the unprecedented polyphosphorus cations of the type [Cp′′′Ni(η³-P₄R₂)][X] (R=Ph ( 2 a ), Mes ( 2 b ), Cy ( 2 c ), 2,2′-biphen ( 2 d ), Me ( 2 e ); [X]⁻=[OTf]⁻, [SbF₆]⁻, [GaCl₄]⁻, [BAr^F]⁻, [TEF]⁻) and [Cp′′′Ni(η³-P₄RCl)][TEF] (R=Ph ( 2 f ), tBu ( 2 g )). In the reaction of 1 with [Br₂P]⁺, an analogous compound is observed only as an intermediate and the final product is an unexpected dinuclear complex [{Cp′′′Ni}₂(μ,η³:η¹:η¹-P₄Br₃)][TEF] ( 3 a ). A similar product [{Cp′′′Ni}₂(μ,η³:η¹:η¹-P₄(2,2′-biphen)Cl)][GaCl₄] ( 3 b ) is obtained, when 2 d [GaCl₄] is kept in solution for prolonged times. Although the central structural motif of 2 a – g consists of a “butterfly-like” folded P₄ ring attached to a {Cp′′′Ni} fragment, the structures of 3 a and 3 b exhibit a unique asymmetrically substituted and distorted P₄ chain stabilised by two {Cp′′′Ni} fragments. Additional DFT calculations shed light on the reaction pathway for the formation of 2 a – 2 g and the bonding situation in 3 a .     

A fast atom bombardment mass spectrometric study of room-temperature 1-ethyl-3-methylimidazolium chloroaluminate(III) ionic liquids. Evidence for the existence of the decachlorotrialuminate(III) anion

Previous studies of 1-ethyl-3-methylimidazolium chloride–aluminium(III) chloride ([emim]Cl–AlCl₃) ionic liquids have been hampered by significant contamination of these liquids by oxide impurities. Treatment of these liquids with phosgene removes the oxide impurities, and the use of a specially constructed sample inlet system for air-sensitive materials permitted them to be studied by fast atom bombardment mass spectrometry. The ions Cl^?, [Cl₂]^?, [AlCl₄]^?, [Al₂Cl₇]^?, [emim]⁺ and [(emim)₂X]⁺ (X = Cl or AlCl₄) were observed for the basic ionic liquid. In addition, the anion [Al₃Cl₁₀]^? was observed for the acidic composition. Within the mass spectrometer, the hydrolyses of [Al₃Cl₁₀]^? to produce [Al₃C_l8O]^? and of [Al₂Cl₇]^? to produce [Al₂Cl₅O]^? were observed. Comparison of these results with published ¹⁷O NMR data suggests that the primary hydrolysis products in acidic ionic liquids are [Al₃Cl₈O]^? and [Al₂Cl₅O]^? and that the principal secondary hydrolysis product is [Al₂Cl₆(OH)]^?.     

9-Triptycenyl complexes of group 13 and 15 halides and hydrides

The reactions of 9-lithiotriptycene with AlCl₃, GaCl₃ and InBr₃ have been carried out and have yielded the complexes, [(tript)AlCl₂(OEt₂)], [(tript)GaCl₂(THF)] and [(tript)InBr(μ-Br)₂Li(OEt₂)₂], tript=9-triptycenyl. The latter two complexes have been structurally characterised. The corresponding reactions of 9-lithiotriptycene with ECl₃ (E=P, As, Sb or Bi) afforded the complexes, [(tript)ECl₂], of which all but the phosphorus compound have been crystallographically authenticated. In addition, the high yield syntheses of the thermally stable primary pnictanes [(tript)EH₂] (E=As, Sb) have been achieved by reaction of the relevant halide complex with LiAlH₄. The X-ray crystal structure of the antimony hydride complex is reported.     

Metalloradical Cations and Dications Based on Divinyldiphosphene and Divinyldiarsene Ligands

Metalloradicals are key species in synthesis, catalysis, and bioinorganic chemistry. Herein, two iron radical cation complexes ( 3-E )GaCl₄ [( 3-E )^.+ = [{(IPr)C(Ph)E}₂Fe(CO)₃]^.+, E = P or As; IPr = C{(NDipp)CH}₂, Dipp = 2,6-iPr₂C₆H₃] are reported as crystalline solids. Treatment of the divinyldipnictenes {(IPr)C(Ph)E}₂ ( 1-E ) with Fe₂(CO)₉ affords [{(IPr)C(Ph)E}₂Fe(CO)₃] ( 2-E ), in which 1-E binds to the Fe atom in an allylic (η³-EEC_vinyl) fashion and functions as a 4e donor ligand. Complexes 2-E undergo 1e oxidation with GaCl₃ to yield ( 3-E )GaCl₄. Spin density analysis revealed that the unpaired electron in ( 3-E )^.+ is mainly located on the Fe (52–64 %) and vinylic C (30–36 %) atoms. Further 1e oxidation of ( 3-E )GaCl₄ leads to unprecedented η³-EEC_vinyl to η³-EC_vinylC_Ph coordination shuttling to form the dications ( 4-E )(GaCl₄)₂.     

A “Push–Pull” Stabilized Phosphinidene Supported by a Phosphine-Functionalized β-Diketiminato Ligand

The use of a bis(diphenyl)phosphine functionalized β-diketiminato ligand, [HC{(CH₃)C}₂{(ortho-[P(C₆H₅)₂]₂C₆H₄)N}₂]⁻ (PNac), as a support for germanium(II) and tin(II) chloride and phosphaketene compounds, is described. The conformational flexibility and hemilability of this unique ligand provide a versatile coordination environment that can accommodate the electronic needs of the ligated elements. For example, chloride abstraction from [(PNac)ECl] (E=Ge, Sn) affords the cationic germyliumylidene and stannyliumylidene species [(PNac)E]⁺ in which the pendant phosphine arms associate more strongly with the Lewis acidic main group element centers, providing further electronic stabilization. In a similar fashion, chemical decarbonylation of the germanium phosphaketene [(PNac)Ge(PCO)] with tris(pentafluorophenyl)borane affords a “push–pull” stabilized phosphinidene in which one of the phosphine groups of the ligand backbone associates with the low valent phosphinidene center.     

Solubility Behaviour of TiCl4, ZrCl4, and HfCl4 in Chloroaluminate Ionic Liquids

The solubility of NbCl₅, TaCl₅, TiCl₄, ZrCl₄, and HfCl₄ in neutral [BMIM][AlCl₄] (BMIM = 1‐butyl‐3‐methylimidazolium) was determined. While TiCl₄ was immiscible with the neutral ionic liquid, 0.80 molar equivalents of ZrCl₄ and stoichiometric amounts of HfCl₄ dissolved in the melt at ambient temperature. The crystal structures and the unit cell parameters of [BMIM]₂[Ti₂Cl₁₀], [BMIM]₂[Zr₂Cl₁₀], and [PhNMe₃][Hf₂Cl₉] were determined. [BMIM]₂[Ti₂Cl₁₀], and [BMIM]₂[Zr₂Cl₁₀] were crystallised from basic chloroaluminate melts. With a trimethylanilinium cation, [PhNMe₃][Hf₂Cl₉] crystallised from an equimolar composition of PhNMe₃Cl, AlCl₃, and HfCl₄. Obviously, HfCl₄ abstracted a chloride ligand from [AlCl₄]^– to give highly Lewis acidic [Al₂Cl₇]^– anions.     

From Silylone to an Isolable Monomeric Silicon Disulfide Complex

The synthesis and characterization of the first bis‐N‐heterocyclic carbene stabilized monomeric silicon disulfide (bis‐NHC)SiS₂ 2 (bis‐NHC=H₂C[{NC(H)C(H)N(Dipp)}C:]₂, Dipp=2,6‐iPr₂C₆H₃) is reported. Compound 2 is prepared in 89 % yield from the reaction of the zero‐valent silicon complex (′silylone′) 1 [(bis‐NHC)Si] with elemental sulfur. Compound 2 can react with GaCl₃ in acetonitrile to give the corresponding (bis‐NHC)Si(S)S→GaCl₃ Lewis acid–base adduct 3 in 91 % yield. Compound 3 is also accessible through the reaction of the unprecedented silylone‐GaCl₃ adduct [(bis‐NHC)Si→GaCl₃] 4 with elemental sulfur. Compounds 2 , 3 , and 4 could be isolated and characterized by elemental analyses, HR‐MS, IR, ¹³C‐ and ²⁹Si‐NMR spectroscopy. The structures of 3 and 4 could be determined by single‐crystal X‐ray diffraction analyses. DFT‐derived bonding analyses of 2 and 3 exhibited highly polar Si S bonds with moderate p_π–p_π bonding character.     

Binuclear organometallic compounds VIII. Oxidative addition of Si-H or Si-Cl compounds to low valent Fe, Co, or Ni complexes stabilised by mono- or bi-dentate phosphines

The reactions of [(Ph₃P)₄Ni], [(Ph₃P)₃CoN₂], [(dp)₂Ni], [(dp)₂CoH], [(dp)₂Fe(C₂H₄)] or [(dp)₂FeH₂] (dp = Ph₂PCH₂CH₂Ph₂P) with Ph_nSiCl_4-n (n = 1, 2, or 3), Ph_nSiH_4-n, X₃SiH (X = Cl or Et), or R₂ClSiH (R = Ph or Me) have been investigated. Solid complexes were isolated which, for the most part, were insoluble in non-polar solvents. Assignments of structures are therefore incomplete, and are based on microanalysis, IR spectra, analogies with established reactions, and (in some cases) chemical degradation. Evidence is presented for the following: (i) for Ni^II, products from [(Ph₃P)₄Ni] and HSiXX′X″ (XX′X″ = Ph₃, Ph₂H or PhH₂), the cyclic [(Ph₃P)₂NiSiCl₂]₂, and the five-coordinate [(dp)₂-NiX]⁺[SiCl₃]^- (X = H or Cl₃Si); (ii) for Co^III, the six-coordinate cis-octahedral [(dp)₂CoH₂]⁺ [SiXX′X″]^- (XX′X″ = Cl₃, Cl₂Me, ClMe₂, or ClPh₂); and for Fe^II, the four-coordinate [(dp)FeH(SiCl₃)] and the six-coordinate [(dp)₂Fe(X)SiCl₃] (X = H, Cl, or Cl₃Si).     

Halogenation and Nucleophilic Quenching: Two Routes to E−X Bond Formation in Cobalt Triple-Decker Complexes (E=As,P; X=F,Cl, Br,I)

The oxidation of [(Cp’’’Co)₂(μ,η² : η²-E₂)₂] (E=As ( 1 ), P ( 2 ); Cp’’’=1,2,4-tri(tert-butyl)cyclopentadienyl) with halogens or halogen sources (I₂, PBr₅, PCl₅) was investigated. For the arsenic derivative, the ionic compounds [(Cp’’’Co)₂(μ,η⁴ : η⁴−As₄X)][Y] (X=I, Y=[As₆I₈]_0.5 ( 3 a ), Y=[Co₂Cl_6-nI_n]_0.5 (n=0, 2, 4; 3 b ); X=Br, Y=[Co₂Br₆]_0.5 ( 4 ); X=Cl, Y=[Co₂Cl₆]_0.5 ( 5 )) were isolated. The oxidation of the phosphorus analogue 2 with bromine and chlorine sources yielded the ionic complexes [(Cp’’’Co)₂(μ-PBr₂)₂(μ-Br)][Co₂Br₆]_0.5 ( 6 a ), [(Cp’’’Co)₂(μ-PCl₂)₂(μ-Cl)][Co₂Cl₆]_0.5 ( 6 b ) and the neutral species [(Cp’’’Co)₂(μ-PCl₂)(μ-PCl)(μ,η¹ : η¹-P₂Cl₃] ( 7 ), respectively. As an alternative approach, quenching of the dications [(Cp’’’Co)₂(μ,η⁴ : η⁴-E₄)][TEF]₂ (TEF=[Al{OC(CF₃)₃}₄]⁻, E=As ( 8 ), P ( 9 )) with KI yielded [(Cp’’’Co)₂(μ,η⁴ : η⁴-As₄I)][I] ( 10 ), representing the homologue of 3 , and the neutral complex [(Cp’’’Co)(Cp’’’CoI₂)(μ,η⁴ : η¹-P₄)] ( 11 ), respectively. The use of [(CH₃)₄N]F instead of KI leads to the formation of [(Cp’’’Co)₂(μ-PF₂)(μ,η² : η¹ : η¹-P₃F₂)] ( 12 ) and 2 , thereby revealing synthetic access to polyphosphorus compounds bearing P−F groups and avoiding the use of very strong fluorinating reagents, such as XeF₂, that are difficult to control.     

Additions- und SubstitutionsReaktionen an Tetrafluor- und Tetrachlordiboran(4)

Addition and Substitution Reactions at Tetrafluoro- and Tetrachlorodiborane(4) From equimolar mixtures of B₂F₄ and Me_nN(SiMe₃)_3-n (n = 0–3) the mono-addition products 1–4 are formed at low temperatures. By elimination of Me₃SiF the adduct 2 gives the dimeric monosubstituted diborane 8 , which slowly decomposes at room temperature to the aminoborane 6 and (BF)_n. The course of the reactions was studied by means of ¹¹B and ¹⁹F NMR spectroscopy and by measuring the vapor pressures. According to the ¹¹B and ³¹P NMR spectra the reaction of B₂Cl₄ with PCl₅ or [Me₄N]Cl in liquid hydrogen chloride at 0°C does not yield [PCl₄]₂⁺[B₂Cl₆]^2? or [Me₄N]₂⁺[B₂Cl₆]^2? but gives [PCl₄]⁺[BCl₄]^?, PCl₃ and BCl₃ or [Me₄N]⁺[BCl₄]^? and BCl₃ besides (BCl)_n.     

The Quest for Stable Silaaldehydes: Synthesis and Reactivity of a Masked Silacarbonyl

The first donor–acceptor complex of a silaaldehyde, with the general formula (NHC)(Ar)Si(H)OGaCl₃ (NHC=N-heterocyclic carbene), was synthesized using the reaction of silyliumylidene–NHC complex [(NHC)₂(Ar)Si]Cl with water in the presence of GaCl₃. Conversion of this complex to the corresponding silacarboxylate dimer [(NHC)(Ar)SiO₂GaCl₂]₂, free silaacetal ArSi(H)(OR)₂, silaacyl chloride (NHC)(Ar)Si(Cl)OGaCl₃, and phosphasilene–NHC adduct (NHC)(Ar)Si(H)PTMS unveil its true potential as a synthon in silacarbonyl chemistry.     

NHC Supersilyl Silver Complex [Ag(IPr)SitBu3] as a Promising Agent for Substitution Reactions

The NHC supersilyl silver complex [Ag(IPr)SitBu₃] (IPr = NHC_IPr) was prepared by treatment of Ag(IPr)Cl with Na(thf)₂[SitBu₃] in benzene/thf at room temperature. X-ray quality crystals of the NHC supersilyl silver complex [Ag(IPr)SitBu₃] (monoclinic, space group P2₁/m) were grown from heptane at room temperature. The ²⁹Si NMR spectrum of a solution of [Ag(IPr)SitBu₃] in C₆D₆ revealed two doublets caused by coupling to ¹⁰⁷Ag and ¹⁰⁹Ag nuclei. We further investigated the possibility of a conversion of triel halides EX₃ by treatment with [Ag(IPr)SitBu₃]. At ambient temperature the reaction of [Ag(IPr)SitBu₃] with an excess of EX₃ yielded tBu₃SiEX₂ (E = B, Al; X = Cl, Br; E = Ga; X = Cl) and IPr · EX₃ (EX₃ = BCl₃, BBr₃, AlCl₃, AlBr₃, GaCl₃). The identity of tBu₃SiEX₂ and IPr · EX₃ was confirmed by comparison with authentic samples.     

Aluminum complexes with mono-and dianionic diimine ligands

The metathesis reaction of the magnesium complex [(dpp-BIAN)²⁻Mg²⁺(THF)₃] (dpp-BIAN is 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) with one equivalent of AlCl₃ in toluene gave the [(dpp-BIAN)²⁻AlCl₂]⁻[Mg₂Cl₃(THF)₆]⁺ complex (1). Reduction of dpp-BIAN with aluminum metal in the presence of AlCl₃ and AlI₃ in toluene and diethyl ether afforded the radical-anionic complex [(dpp-BIAN)⁻AlCl²] (2) and the dianionic complexes [(dpp-BIAN)²⁻AlI(Et₂O)] (3) and [(dpp-BIAN)²⁻AlCl(Et₂O)] (4), respectively. Compounds 1–4 were isolated in the crystalline state and characterized by IR spectroscopy and elemental analysis. The structures of compounds 1–3 were established by X-ray diffraction. Compound 2 was characterized by ESR spectroscopy. Compounds 3 and 4 were studied by 1H and 13C NMR spectroscopy. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 409–415, March, 2006.     

Isolation of a Labile Homoleptic Diazenium Cation

Following our interest in nitrogen chemistry, we now describe the synthesis, structure, and bonding of labile disilylated diazene, its GaCl₃ adduct, and the intriguing trisilylated diazenium ion [(Me₃Si)₂N?N‐SiMe₃]⁺, a dark blue and highly labile (T_decomp>?30 °C) homoleptic cation of the type [R₃N₂]⁺. Although direct silylation of Me₃Si‐N?N‐SiMe₃ failed, the [(Me₃Si)₂N?N‐SiMe₃]⁺ ion was generated in a straightforward two‐electron oxidation reaction from mercury(II) dihydrazide and Ag[GaCl₄]. Moreover, previous structure data of Me₃Si‐N?N‐SiMe₃ were revised on the basis of new data.