Reactions of Polyarsenides with Acetylene: Synthesis and Characterization of [Cs([18]crown‐6)]2As7C14H11·6NH3 and As2C6H6

The reaction of Cs₃As₇ with diphenylacetylene in the presence of 18 crown‐6 in liquid ammonia results in the formation of the new compound [Cs( 18 crown‐6)]₂As₇C₁₄H₁₁ · 6NH₃, which crystallizes in black monoclinic crystals. It contains the first monosubstituated heptaarsenide anion with a hydrocarbon‐only substituent and theoretical calculations show a significant influence of the organic substituent on the electronic structure within the cage. The (Z)‐1, 2‐diphenylethenyl‐heptaarsenide di‐anion can be seen as the first step towards the formation of 1, 2,3‐triarsolides. Further experiments regarding the reaction of Rb₃As₁₁ and Cs₃As₁₁ with acetylene gas in liquid ammonia reveal the formation of the diarsabarrelene As₂C₆H₆, which crystallizes as colorless orthorhombic crystals. Calculations based on the structural data obtained by X‐ray crystallography show the electronically inert character of the arsenic lone pair.     

Tetrahedral [Tt4]4– Zintl Anions Through Solution Chemistry: Syntheses and Crystal Structures of the Ammoniates Rb4Sn4·2NH3, Cs4Sn4·2NH3, and Rb4Pb4·2NH3

The crystalline isotypic solvates Rb₄Sn₄·2NH₃, Cs₄Sn₄·2NH₃, and Rb₄Pb₄·2NH₃ have been synthesized using the direct reduction of elemental tin or tetraphenyltin, respectively, with heavier alkali metals or the dissolution of the binary phase RbPb in liquid ammonia. These compounds contain the cluster ions [Sn₄]^4– or [Pb₄]^4– respectively. This is the first time that[Tt₄]^4– ions (Tt = tetrels) are detected as result of a solution reaction. The accommodation of the ammonia molecules, which build up ion‐dipole interactions to alkali metal cations, requires some modifications of the crystal structures compared to the binary phases RbSn, CsSn, and RbPb. The tetrahedral [Tt₄]^4– anions have a slightly lower coordination by Rb⁺ or Cs⁺ cations and, furthermore, the intercluster distances show a remarkable increase.     

Si44– in Solution – First Solvate Crystal Structure of the Ligand‐free Tetrasilicide Tetraanion in Rb1.2K2.8Si4·7NH3

We report the first solvate structure of the silicide anion Si₄^4–, which provides circumstantial evidence of the stability of the highly charged anion in liquid ammonia solutions. The solvate Rb_1.2K_2.8Si₄ · 7NH₃ crystallized from a mixture of the ternary compound K₆Rb₆Si₁₇ with the transition metal complex [(C₆H₅)₃P]₂Ni(CO)₂ [bis(triphenylphosphine)dicarbonylnickel] in the presence of the chelating agents 18‐crown‐6 (1,4,7,10,13,16‐hexaoxacyclooctadecane) and [2.2.2]cryptand (4,7,13,16,21,24‐hexaoxa‐1,10‐diazabicyclo[8.8.8]hexacosane) in liquid ammonia. Single X‐ray diffraction analysis confirms the presence of the Si₄^4– anion in the crystal structure of Rb_1.2K_2.8Si₄ · 7NH₃, which represents the first solvate compound of the naked tetrasilicide tetraanion. All five crystallographically independent cation positions show mixed occupancy by Rb⁺ and K⁺.     

{nBuMg(OR)}2 und {Mg(OR)2}2 (R = 2, 4, 6‐tBu3C6H2) – sterisch überfrachtete Magnesiumalkoholate

Reaction of 2, 4, 6‐tri‐tert‐butylphenol ( 1 ) with di‐n‐butylmagnesium in the molar ratio 1:1 allows the synthesis of {(nBu)Mg(μ‐OR)₂Mg(nBu)} ( 2 ) (R = 2, 4, 6‐tBu₃C₆H₂), which reacts with excess 1 to give the homoleptic alcoholate complex {(RO)Mg(μ‐OR)₂Mg(OR)} ( 3 ) (R = 2, 4, 6‐tBu₃C₆H₂). The structures of 2 and 3 were determined by X‐ray crystallography.     

Silver–Ethene Complexes [Ag(η2‐C2H4)n][Al(ORF)4] with n=1, 2, 3 (RF=Fluorine‐Substituted Group)

Compounds including the free or coordinated gas‐phase cations [Ag(η²‐C₂H₄)_n]⁺ (n=1–3) were stabilized with very weakly coordinating anions [A]^? (A=Al{OC(CH₃)(CF₃)₂}₄, n=1 ( 1 ); Al{OC(H)(CF₃)₂}₄, n=2 ( 3 ); Al{OC(CF₃)₃}₄, n=3 ( 5 ); {(F₃C)₃CO}₃Al‐F‐Al{OC(CF₃)₃}₃, n=3 ( 6 )). They were prepared by reaction of the respective silver(I) salts with stoichiometric amounts of ethene in CH₂Cl₂ solution. As a reference we also prepared the isobutene complex [(Me₂C?CH₂)Ag(Al{OC(CH₃)(CF₃)₂}₄)] ( 2 ). The compounds were characterized by multinuclear solution‐NMR, solid‐state MAS‐NMR, IR and Raman spectroscopy as well as by their single crystal X‐ray structures. MAS‐NMR spectroscopy shows that the [Ag(η²‐C₂H₄)₃]⁺ cation in its [Al{OC(CF₃)₃}₄]^? salt exhibits time‐averaged D_3h‐symmetry and freely rotates around its principal z‐axis in the solid state. All routine X‐ray structures (2θ_max.<55°) converged within the 3σ limit at C?C double bond lengths that were shorter or similar to that of free ethene. In contrast, the respective Raman active C?C stretching modes indicated red‐shifts of 38 to 45 cm^?1, suggesting a slight C?C bond elongation. This mismatch is owed to residual librational motion at 100 K, the temperature of the data collection, as well as the lack of high angular data owing to the anisotropic electron distribution in the ethene molecule. Therefore, a method for the extraction of the C?C distance in [M(C₂H₄)] complexes from experimental Raman data was developed and meaningful C?C distances were obtained. These spectroscopic C?C distances compare well to newly collected X‐ray data obtained at high resolution (2θ_max.=100°) and low temperature (100 K). To complement the experimental data as well as to obtain further insight into bond formation, the complexes with up to three ligands were studied theoretically. The calculations were performed with DFT (BP86/TZVPP, PBE0/TZVPP), MP2/TZVPP and partly CCSD(T)/AUG‐cc‐pVTZ methods. In most cases several isomers were considered. Additionally, [M(C₂H₄)₃] (M=Cu⁺, Ag⁺, Au⁺, Ni⁰, Pd⁰, Pt⁰, Na⁺) were investigated with AIM theory to substantiate the preference for a planar conformation and to estimate the importance of σ donation and π back donation. Comparing the group 10 and 11 analogues, we find that the lack of π back bonding in the group 11 cations is almost compensated by increased σ donation.     

The Features of Interaction of Bis(4, 6‐di‐tert‐butyl‐N‐(2, 6‐diisopropylphenyl)‐o‐amidophenolato)tin(IV) with Bromine and Iodine

The oxidation of tin(IV) bis‐amidophenolate (APiPr)₂Sn · THF ( I ) by bromine and iodine leads to the formation of monoradical mixed‐ligand complexes (APiPr)(ISQiPr)SnBr · THF ( II ) and (APiPr)(ISQiPr)SnI · THF ( III ) or diradical complexes (ISQiPr)₂SnBr₂ ( IV ) and (ISQiPr)₂SnI₂ ( V ), respectively [APiPr = dianion 4, 6‐di‐tert‐butyl‐N‐(2, 6‐diisopropylphenyl)‐o‐amidophenolate; ISQiPr = radical‐anion 4, 6‐di‐tert‐butyl‐N‐(2, 6‐diisopropylphenyl)‐o‐iminobenzosemiquinone], depending on the molar ratio of reagents (2:1 or 1:1). According to EPR data for compounds II and III , the unpaired electron is delocalized between both organic ligands. The EPR spectrum of IV in toluene matrix at 130 K is typical for diradical species with S = 1 with parameters D = 530 G, E = 105 G. The mixed‐ligand complexes II and III are unstable and undergo to symmetrization leading to formation of IV or V . The molecular structures of IV and V are determined by X‐ray analysis.     

Major Distinctions in the Molecular and Supramolecular Structures of Selenium‐containing Organotins, (o‐MeSe‐C6H4CH2)SnPh3–nCln (n = 0, 1, 2)

The synthesis and characterization of selenium‐containing stannanes, (o‐MeSeC₆H₄CH₂)Sn(Ph)_3–nCl_n [n = 0 ( 1Se ); 1 ( 2Se ); 2 ( 3Se )], is presented. The increasing Lewis acidity at tin in the series 1Se → 2Se → 3Se is reflected in their respective solid state arrangements and supramolecular architecture by interactions of the type Se ··· Se, Sn ··· Se, and Cl ··· H–C. Overall the capacity of the selenium atom to form bidentate interactions creates geometric assemblies distinctly different to those of the oxygen and sulfur analogs.     

Kristallstrukturen der iso‐Thiocyanatoberyllate (Ph4P)2[Be(NCS)4] und (Ph4P)4[{Be2(NCS)4(μ‐NCS)2}{Be2(NCS)6(μ‐H2N2C2S2)}]

Bis(tetraphenylphosphonium) hexachloridodiberyllate, (Ph₄P)₂[Be₂Cl₆], reacts with excess trimethylsilyl‐iso‐thiocyanate to give a mixture of colourless single crystals of (Ph₄P)₂[Be(NCS)₄] ( 1 ) and (Ph₄P)₄[{Be₂(NCS)₄(μ‐NCS)₂}{Be₂(NCS)₆(μ‐H₂N₂C₂S₂)}] ( 2 ), which can be separated by selection. Both complexes were characterized by X‐ray diffraction. Compound 1 can be prepared without by‐products by treatment of (Ph₄P)₂[BeCl₄] with excess Me₃SiNCS in dichloromethane solution. 1 : Space group I4₁/a, Z = 4, lattice dimensions at 100(2) K: a = b = 1091.2(1), c = 3937.1(3) pm, R₁ = 0.0474. The [Be(NCS)₄]^2– ion of 1 forms tetragonally distorted tetrahedral anions with Be–N distances of 168.4(2) pm and weak intermolecular S ··· S contacts along [100] and [010]. 2 ·4CH₂Cl₂: Space group P , Z = 1, lattice dimensions at 100(2) K: a = 919.5(1), b = 1248.3(1), c = 2707.0(2) pm, α = 101.61(1) °, β = 95.08(1) °, γ = 94.52(1) °, R₁ = 0.103. Compound 2 contains two different anionic complexes in the ratio 1:1. In {Be₂(NCS)₄(μ‐NCS)₂}^2–, the beryllium atoms are connected by (NCS)^– bridging groups forming centrosymmetric eight‐membered Be₂(NCS)₂ rings with distances Be–N of 168(1) pm and Be–S of 235.2(9) pm. The second anion {Be₂(NCS)₆(μ‐H₂N₂C₂S₂)}^2– consists of two {Be(NCS)₃}^– units, which are linked by the nitrogen atoms of the unique dimeric cyclo‐addition product of HNCS with Be–N distances of 179(1) pm.     

Synthesis and Investigation of 1,3‐Bis(5‐nitraminotetrazol‐1‐yl)propan‐2‐ol and its Salts

1,3‐Bis(5‐nitraminotetrazol‐1‐yl)propan‐2‐ol ( 5 ) was prepared by the reaction of 5‐aminotetrazole and 1,3‐dichloroisopropanol under basic conditions. Obtained 1,3‐bis(5‐aminotetrazol‐1‐yl)propan‐2‐ol ( 3 ) was nitrated with 100 % nitric acid. In this context in situ hydrolysis of the nitrate ester was studied. Metal and nitrogen‐rich salts of the neutral compound 5 were prepared and analyzed. Crystal structures of three salts and the sensitivities toward impact, friction and electrostatic discharge were determined as well. The performance values of the compounds were calculated using the EXPLO5 program. A detailed comparison of the different salts is also enclosed.     

Novel Arachno‐type X56– Zintl Anions in Sr3Sn5, Ba3Sn5, and Ba3Pb5 and Charge Influence on Zintl Clusters

Two new binary Zintl phases, Sr₃Sn₅ and Ba₃Sn₅ were synthesized and structurally characterized. The revised structure of Ba₃Pb₅ is also reported. All three compounds are isotypic and crystallize with a modified Pu₃Pd₅ structure type. The anionic substructure is composed of X₅^6– square pyramidal clusters (X = Sn, Pb), which are described as arachno clusters according to the Wade‐Mingos electron counting rules. The electronic structure of the pyramidal Zintl anions and the influence of the number of skeletal electrons of these clusters are investigated using the electron localization function (ELF). The structural relationship between Ba₃Sn₅ and the Zintl phases Ba₃Si₄ and Ba₃Ge₄ are analyzed. Additionally, two new Zintl phases Ba₃Ge_2.82Sn_2.18 and Ba₃Ge_3.94Sn_0.06, have been synthezised and their structures are reported, which directly show that the exchange of tin against germanium leads to a change from the M₃X₅ to the M₃X₄ structure type. This effect is traced back to the maximal charge acquisition property of the Zintl anions of heavier and lighter tetralides.     

Transformation of a Cp*–Iridium(III) Precatalyst for Water Oxidation when Exposed to Oxidative Stress

The reaction of [Cp*Ir(bzpy)NO₃] ( 1 ; bzpy=2‐benzoylpyridine, Cp*=pentamethylcyclopentadienyl anion), a competent water‐oxidation catalyst, with several oxidants (H₂O₂, NaIO₄, cerium ammonium nitrate (CAN)) was studied to intercept and characterize possible intermediates of the oxidative transformation. NMR spectroscopy and ESI‐MS techniques provided evidence for the formation of many species that all had the intact Ir–bzpy moiety and a gradually more oxidized Cp* ligand. Initially, an oxygen atom is trapped in between two carbon atoms of Cp* and iridium, which gives an oxygen–Ir coordinated epoxide, whereas the remaining three carbon atoms of Cp* are involved in a η³ interaction with iridium ( 2 a ). Formal addition of H₂O to 2 a or H₂O₂ to 1 leads to 2 b , in which a double MeCOH functionalization of Cp* is present with one MeCOH engaged in an interaction with iridium. The structure of 2 b was unambiguously determined in the solid state and in solution by X‐ray single‐crystal diffractometry and advanced NMR spectroscopic techniques, respectively. Further oxidation led to the opening of Cp* and transformation of the diol into a diketone with one carbonyl coordinated at the metal ( 2 c ). A η³ interaction between the three non‐oxygenated carbons of “ex‐Cp*” and iridium is also present in both 2 b and 2 c . Isolated 2 b and mixtures of 2 a – c species were tested in water‐oxidation catalysis by using CAN as sacrificial oxidant. They showed substantially the same activity than 1 (turnover frequency values ranged from 9 to 14 min^?1).     

Cleavage of the Fe—Fe Bond of （Me2SiSiMe2） [η^5－C5H4Fe（CO）2]2 with Na／Hg and Molecular Structure of the Ring－Opened Complex

The reaction of the rifle cyclic complex (1) with sodium amalgam in THF resulted in the expected cleavage of the Fe-Fe bond to afford his-sodium salt ( Me2SiSiMe2 ) [η^5-C5H4Fe(CO)2]2 (4). The latter was not isolated and was used directly to react with MeI, PhCH2Cl, CH3C(O)Cl, PhC(O)Cl,Cy3SnCl (Cy= cyclohexyl) or Ph3SnCl to afford corresponding ring-opened derivatives (Me2SiSiMe2) [η^5-C5H4Fe(CO)2]2 [5, R=Me; 6, R=PhCH2; 7, R=CH3C(O); 8, R=PhC(O); 9, R = Cy3Sn or 10, R = Ph3Sn ]. The crystal and molecular structures of 10 were determined by X-ray diffraction analysis. The molecule took the desired ant/ conformation around the Si-Si bond. The length of the Si--Si bond is 0.2343(3)nm, which is essentially identical to that in the cyclic structure of 1[0.2346(4) tun]. This result unambiguously demonstrates that the Si--Si bond in the cyclic structure of 1 is not subject to obvious strain.     

Regioselective Cage Opening of La2@D2(10611)‐C72 with 5,6‐Diphenyl‐3‐(2‐pyridyl)‐1,2,4‐triazine

The thermal reaction of the endohedral metallofullerene La₂@D₂(10611)‐C₇₂, which contains two pentalene units at opposite ends of the cage, with 5,6‐diphenyl‐3‐(2‐pyridyl)‐1,2,4‐triazine proceeded selectively to afford only two bisfulleroid isomers. The molecular structure of one isomer was determined using single‐crystal X‐ray crystallography. The results suggest that the [4+2] cycloaddition was initiated in a highly regioselective manner at the C? C bond connecting two pentagon rings of C₇₂. Subsequent intramolecular electrocyclization followed by cycloreversion resulted in the formation of an open‐cage derivative having three seven‐membered ring orifices on the cage and a significantly elongated cage geometry. The reduction potentials of the open‐cage derivatives were similar to those of La₂@D₂‐C₇₂ whereas the oxidation potentials were shifted more negative than those of La₂@D₂‐C₇₂. These results point out that further oxidation could occur easily in the derivatives.     

The Zintl Phase Cs7NaSi8 – From NMR Signal Line Shape Analysis and Quantum Mechanical Calculations to Chemical Bonding

Powder samples as well as red and transparent single crystals of the Zintl phase Cs₇NaSi₈ were synthesized and characterized by means of X‐ray diffraction and differential thermal analysis. Cs₇NaSi₈ was found to be isotypic to the recently reported phase Rb₇NaSi₈. It crystallizes in the Rb₇NaGe₈ structure type forming trigonal pyramidal Si₄^4– anions. Two unique environments of the cations are observed, a linear arrangement [Na(Si₄)₂]^7– with short Na–Si distances of 3.0 Å and a Cs2 atom coordinated by six Si₄^4– anions with long Cs–Si distances of 4.2 Å. The bonding situation was investigated by a combined application of ²⁹Si, ²³Na, and ¹³³Cs solid‐state NMR spectroscopy and quantum mechanical calculations of the NMR coupling parameters. In addition the electronic density of states (DOS), the electron localizability indicator (ELI) and the atomic charges using the QTAIM approach were studied. Good agreement of the calculated and experimental values of the NMR coupling parameters was obtained. An anisotropic bonding situation of the silicon atoms is indicated by the chemical shift anisotropy being similar to Rb₇NaSi₈. Confirmation is given by the observation of one lone‐pair‐like feature for each silicon atom and two types of two‐center Si–Si bonds using the ELI. Calculation and NMR spectroscopic determination of the ²³Na and ¹³³Cs electric field gradients prove anisotropies of the charge distribution around the cations. Due to the similar values for the Na atoms in M₇NaSi₈ (M = Rb, Cs) equal bonding situations can be concluded. The much larger anisotropy of the charge distribution of the Cs atoms can be addressed as the main difference to Rb₇NaSi₈.     

Synthesis and Crystal Structure of [Nd(η6‐1, 3, 5‐C6H3Me3)‐(AlCl4)3](C6H6) and Structural Comparison of Ln(η6‐arene)‐(AlCl4)3

Reaction of Ndcl₃ with AlCl₃ and mesitylene in benzene gives complex [Nd(η⁶‐1, 3, 5‐C₆H₃Me₃)‐(AlCl₄)₃](C₆H₆) (1) which was characterized by elemental analysis, IR spectra, MS and X‐ray diffractions. The X‐ray determination indicates that 1 has a distorted pentagonal bipyramidal geometry and crystallizes in the monoclinic, space group P2₁/n with a = 0.9586(2), b = 1.1717(5), c = 2.8966(7) nm, β = 90.85 (2)°, V = 3.2529 (6) nm³,D_c= 1.573 g/cm³, Z = 4. A comparison of bond parameters for all the reported Ln (η⁶‐Ar) (AlCl₄)₃ complexes indicates that the bond distance of La? C is shortened with the increasing of methyl group on benzene and with the decreasing of radius of lanthanide ions.     

The Protonation of Acetamide and Thioacetamide in Super­acidic Solutions: Crystal Structures of [H3CC(OH)NH2]+AsF6– and [H3CC(SH)NH2]+AsF6–

Acetamide and thioacetamide react with the superacid solutions HF/MF₅ (M = As, Sb) under formation of the corresponding salts [H₃CC(OH)NH₂]⁺MF₆^– and [H₃CC(SH)NH₂]⁺MF₆^– (M = As, Sb), respectively. The reaction of DF/AsF₅ with acetamide and thioacetamide lead to the corresponding deuterated salts [H₃CC(OD)ND₂]⁺AsF₆^– and [H₃CC(SD)ND₂]⁺AsF₆^–, respectively_. The salts are characterized by vibrational and NMR spectroscopy, and in the case of [H₃CC(OH)NH₂]⁺AsF₆^– and [H₃CC(SH)NH₂]⁺AsF₆^– also by single‐crystal X‐ray analyses. The [H₃CC(OH)NH₂]⁺AsF₆^– ( 1 ) salt crystallizes in the triclinic space group P$\bar{1}$ with two formula units per unit cell, and the [H₃CC(SH)NH₂]⁺AsF₆^– ( 2 ) salt crystallizes in the monoclinic space group P2₁/c with four formula units per unit cell. In both crystal structures three‐dimensional networks are observed which are formed by intra‐ and intermolecular N–H ··· F and O–H ··· F or S–H ··· F hydrogen bonds, respectively. For the vibrational analyses, quantum chemically calculated spectra of the cations [H₃CC(OH)NH₂ · 3HF]⁺ and [H₃CC(SH)NH₂ · 2HF]⁺ are considered.     

Synthesis and X‐ray Crystal Structures of Ru3(CO)9(μ‐arphos)(L) [L = AsPh3, As(m‐C6H4Me)3, As(p‐C6H4Me)3]

Three new triruthenium clusters, Ru₃(CO)₉(μ‐arphos)AsPh₃ ( 1 ), Ru₃(CO)₉(μ‐arphos)As(m‐C₆H₄Me)₃ ( 2 ), and Ru₃(CO)₉(μ‐arphos)As(p‐C₆H₄Me)₃ ( 3 ) were synthesized via thermal reactions of Ru₃(CO)₁₀(μ‐arphos) with different tertiary arsine ligands [AsPh₃, As(m‐C₆H₄Me)₃, As(p‐C₆H₄Me)₃]. All these complexes were fully characterized by elemental analysis, FT‐IR, NMR spectroscopy, and single‐crystal X‐ray diffraction.