Molecular Ionics in Supramolecular Assemblies with Channel Structures Containing Lithium Ions

A novel trilithium compound, Li₃[B(C₆H₄O₂){O(CH₂CH₂O)₃CH₃}₂][N(SO₂CF₃)₂]₂ ( 1 ‐2.0), with solid‐state ionic conductivity was synthesized. The crystal structure of 1 ‐2.0 consists of the one‐dimensional ionic conduction paths. The paths were afforded as a result of the self‐assembled stacking of the component molecules of 1 ‐2.0 with channel structures containing lithium ions. In this supramolecule, one lithium ion holds the component molecules in specific positions to construct a supramolecular structure with thermally stable ionic conduction paths and the others behave as carrier ions exhibiting selective lithium‐ion conductivity. Owing to the existence of both roles for the lithium ions, this electrolyte shows selective lithium‐ion conductivity.     

Synthese und Struktur des tetrameren Tris(trimethylsilyl)silylindium(I) und neuer silylsubstituierter Indiumverbindungen

Synthesis and Structure of Tetrameric Tris(trimethylsilyl)indium(I) and of New Silyl substituted Indium Compounds The reaction of InCp* with [LiSi(SiMe₃)₃·3thf] yielded in the first silylsubstituted tetrahedrane of indium [In₄{Si(SiMe₃)₃}₄] ( 1 ). It crystallizes together with [In{Si(SiMe₃)₃}₃] ( 2 ) in dark green crystals. Colourless crystals of [Li(OH)(OSiMe₃)In{Si(SiMe₃)₃}₂]₂ ( 3 ) were isolated as a byproduct from this reaction. It's structural core are three connected four membered rings made up of In‐, Li‐ and O‐atoms. From the reaction of [InOSO₂CF₃] with [LiSi(SiMe₃)₃·3thf] colourless crystals of [In{Si(SiMe₃)₃}₂OSO₂CF₃·thf] ( 4 ) were isolated. InCp* reacted with [LiSiMe(SiMe₃)₂·3thf] to form the orange‐coloured monoindane [In{SiMe(SiMe₃)₂}₃] ( 5 ). 1 – 4 were characterized by X‐ray crystal structure analyses.     

Unterscheidung enantiotoper/diastereotoper Protonen und regioselektive Spinentkopplung in metallorganischen Komplexen mit Hilfe von Shiftreagenzien

Dimethylphosphonate HP(O)(OCH₃)₂ and the dimethylphosphonate complexes [(C₅H₅)MX{P(O) (OCH₃)₂}{P(OCH₃)₃}] (M=Co, Rh; X=I, CH₃), [(C₅H₅)Co{P(O)(OCH₃)₂}₂ {P(OH)(OCH₃)₂}] and [(C₅H₅)Ni{P(O)(OCH₃)₂}{P(OCH₃)₃}] have been studied by ¹H n.m.r. spectroscopy. The chiral shift reagent Eu(tfc)₃ has been used to resolve the spectra of the enantiomeric mixtures of [(C₅H₅)MX {P(O)(OCH₃)₂}{P(OCH₃)₃}]. The substituent X in [(C₅H₅)MX{P(O)(OCH₃)₂}{P(OCH₃)₃}] has a strong influence on the anischrony of the diastereotopic phosphonate methyls in the presence of Eu(tfc)₃. The same shift reagent also resolves the enantiotopic protons in HP(O)(OCH₃)₂ but not in [(C₅H₅)Ni {P(O)(OCH₃)₂}{P(OCH₃)₃}]. The addition of Eu(tfc)₃ to [(C₅H₅)Ni{P(O)(OCH₃)₂}{P(OCH₃)₃}] eliminates the ³J(POCH) coupling in the coordinated dimethylphosphonate. The cobalt complex [(C₅H₅)Co{P(O)(OCH₃)₂}₂{P(OH)(OCH₃)₂}] reacts as a chelating ligand with Eu(tfc)₃ to give one tfcH per Eu(tfc)₃.     

A comparison of local structures in crystalline P(EO)3LiCF3SO3 and glyme-LiCF3SO3 systems

The newly discovered crystal structures of CH₃(OCH₂CH₂)OCH₃(LiCF₃SO₃)₂, monoglyme:(LiTf)₂, and CH₃(OCH₂CH₂)₃OCH₃(LiCF₃SO₃)₂, triglyme:(LiTf)₂, are briefly described. The coordination of lithium cations and the CF₃SO₃⁻ anions in these structures is compared with the cation and anion coordination in the crystalline phase of high molecular weight P(EO)₃LiCF₃SO₃. Comparison is also made with the previously reported crystalline phase of CH₃(OCH₂CH₂)₂OCH₃LiCF₃SO₃, diglyme:LiTf. A tendency to form trans-gauche-trans conformations for the bond order -O-C-C-O- is noted in adjacent ethylene oxide sequences interacting with a five-coordinate lithium ion.     

Lithium insertion into titanium dioxide (anatase) electrodes: microstructure and electrolyte effects

Insertion characteristics of anatase electrodes were studied on single-crystal and polycrystalline electrodes of different microstructures. The lithium incorporation from propylene carbonate solution containing LiClO₄ and Li(CF₃SO₂)₂N was studied by means of cyclic voltammetry (CV), the quartz crystal microbalance (QCM) and the galvanostatic intermittent titration technique (GITT). The electrode microstructure affects both the accessible coefficient x and the reversibility of the process. The highest insertion activity was observed for electrodes composed of crystals with characteristic dimensions of ∼10^–8 m. The insertion properties deteriorate for higher as well as for smaller crystal sizes. Enhanced insertion was observed in Li(CF₃SO₂)₂N-containing solutions. Lithium insertion is satisfactorily reversible for mesoscopic electrodes; the reversibility in the case of compact polycrystalline and single-crystal electrodes is poor. The reversibility of the insertion improves with increasing electrolyte concentration. The lithium diffusion coefficient decreases with increasing x and ranges between 10^–15 and 10^–18 cm² s^–1. Electronic Publication     

Synthesis and Structure of [Hg{OP(O)CF3(OH)}2(PMe3)3], a Distorted Trigonal Bipyramidal Complex Connected by Hydrogen Bridges to Polymeric Chains

The hydrolysis of [Hg{P(CF₃)₂}₂(PMe₃)₂] yields colourless crystals of [Hg{OP(O)CF₃(OH)}₂(PMe₃)₃]. The proposed multistep reaction proceeds via primary hydrolysis of the starting material giving HgO and HP(CF₃)₂. The latter is directly oxidized by HgO to (CF₃)₂P(O)OH. The bis(trifluoromethyl)phosphinic acid hydrolyses to CF₃P(O)(OH)₂ which reacts with [Hg{P(CF₃)₂}₂(PMe₃)₂] in the presence of PMe₃ to the title compound. The crystal structure was determined by X‐ray single‐crystal analysis (triclinic; P1¯; a = 860.7(1), b = 1007.6(2), c = 1625.0(3) pm; α = 96.09(2), β = 101.09(2), γ = 107.79(2)°; Z = 2) and exhibits distorted trigonal bipyramidal mercury complexes which are connected to polymeric chains. The acidic units, {OP(O)CF₃(OH)}^—, are connected via intermolecular hydrogen bridges, forming two individual centrosymmetric eight membered rings with asymmetric hydrogen bridges with O—O distances of 249.4(8) and 250.8(8) pm.     

Probing the effect of anion structure on the physical properties of cationic 1,2,3‐triazolium‐based poly(ionic liquid)s

To extensively explore the influence of anion structure on the physical properties of poly(ionic liquid)s (PILs) a series of PILs having main‐chain 1,2,3‐triazolium cations was synthesized via copper(I)‐catalyzed azide‐alkyne 1,3‐dipolar cycloaddition (CuAAC) followed by N‐alkylation with iodomethane and anion metathesis with different metal salts, that is, Li(CF₃SO₂)₂N, Li(CF₃CF₂SO₂)₂N, K(FSO₂)₂N, K(CF₃SO₂)N(CN), Ag(CN)₂N, and sodium 4,5‐dicyano‐1,2,3‐triazolate. To isolate the effect of anion on physical properties of PILs, a common iodide precursor was used to maintain constant the average degree of polymerization (DP_n) and chain dispersity. Detailed structure/properties relationship analyses demonstrated a lack of correlation between anion chemical structure, ionic conductivity, and glass transition temperatures. Among synthesized series, the PIL derivative having bis(trifluoromethylsulfonyl)imide counter anion showed the best compromise in performance: low glass transition temperature (T_g = ?68 °C), high thermal stability (T_onset = 340 °C) and superior ionic conductivity (σ_DC = 8.5 × 10^{? 6} S/cm at 30 °C), which makes it an interesting candidate for various key modern electrochemical applications. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 2191–2199     

Chemical transformation of bis((perfluoroalkyl)sulfonyl)methanes and 1,1,3,3‐tetraoxopolyfluoro‐1,3‐dithiaycloalkanes

Halogenation of the potassium or silver salts of bis((trifluoromethyl)sulfonyl)methane(CF₃SO₂)₂CH₂ and its cyclo analogues (CF₂)_nSO₂‐CH₂SO₂CF₂ with N‐fluoro‐bis((trifluoromethyl)sul‐fonyl)imine (CF₃SO₂)₂NF, chlorine or bromine gave good yields of the corresponding α‐halo disulfones (CF₃SO₂)₂CHX and (CF₂)_nSO₂CHXSO₂CF₂ (X: F, Cl, Br; n = 1,2). Some chemical transformations of these fluorinated α‐halo‐disulfones are described. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 147–151, 1999     

Syntheses of novel delocalized cations and fluorinated anions,new fluorinated solvents and additives for lithium ion batteries

To improve the properties of rechargeable lithium ion batteries, like conductivity, SEI-formation, thermal and electrochemical stability, low and high temperature performance and safety new electrolyte salts, novel solvents (co-solvents) and additives have been synthesized. All new anions, solvents and additives contain fluorine proving the importance of this element for the electrolyte system. Tetrafluoroborates having bulky delocalized nitrogen-, phosphorus and sulfur-centered counter-cations containing tetramethylguanidyl substituents, like [(Me₂N)₂CNC(NMe₂)₂]⁺, have been prepared to improve the conductivity in polymer electrolytes. The hitherto unknown lithium sulfonate, MeOCF₂CF₂SO₃Li, has been successfully synthesized along with further analogs, and also MeOCF₂CF(CF₃)SO₃Li was obtained, both from precursors, FO₂SCF₂C(O)F or FO₂SCF(CF₃)C(O)F accessible by ring opening reactions from the respective sultones. For the lithium salt CF₃OCF(CF₃)SO₃Li, a new simple synthetic pathway was found where CF₃OCFCF₂ and SO₂F₂ were used as precursors. Novel possible redox shuttles, namely (CF₃)₅C₆OLi and fluorinated pyridine-N-oxides have been prepared. A neutral cyclic carben-PF₅ adduct turned out to be a very effective overcharge protection additive. The family of cyclic and acyclic carbonates playing a key-role as electrolyte solvents in lithium ion batteries could be extended by derivatives of 1,1,1,4,4,4-hexafluorobutandiol. Reaction products from perfluoropropene oxide and alcohols, ROC(F)CF₃C(O)OR (R = CH₂CF₃, CH₂CH₂, CH(CF₃)₂) were obtained according to new optimized methods. New cyclic sulfonamides synthesized from FO₂SCF₂C(O)F and FO₂SCF(CF₃)C(O)F could be successfully identified as versatile electrolyte additives.     

One‐Dimensional Polymers Based on Silver(I) Cations and Organometallic cyclo‐P3 Ligand Complexes

The synthesis and characterization of the first supramolecular aggregates incorporating the organometallic cyclo‐P₃ ligand complexes [Cp^RMo(CO)₂(η³‐P₃)] (Cp^R=Cp (C₅H₅; 1a ), Cp* (C₅(CH₃)₅; 1b )) as linking units is described. The reaction of the Cp derivative 1a with AgX (X=CF₃SO₃, Al{OC(CF₃)₃}₄) yields the one‐dimensional (1D) coordination polymers [Ag{CpMo(CO)₂(μ,η³:η¹:η¹‐P₃)}₂]_n[Al{OC(CF₃)₃}₄]_n ( 2 ) and [Ag{CpMo(CO)₂(μ,η³:η¹:η¹‐P₃)}₃]_n[X]_n (X=CF₃SO₃ ( 3a ), Al{OC(CF₃)₃}₄ ( 3b )). The solid‐state structures of these polymers were revealed by X‐ray crystallography and shown to comprise polycationic chains well‐separated from the weakly coordinating anions. If AgCF₃SO₃ is used, polymer 3a is obtained regardless of reactant stoichiometry whereas in the case of Ag[Al{OC(CF₃)₃}₄], reactant stoichiometry plays a decisive role in determining the structure and composition of the resulting product. Moreover, polymers 3a, b are the first examples of homoleptic silver complexes in which Ag^I centers are found octahedrally coordinated to six phosphorus atoms. The Cp* derivative 1b reacts with Ag[Al{OC(CF₃)₃}₄] to yield the 1D polymer [Ag{Cp*Mo(CO)₂(μ,η³:η²:η¹‐P₃)}₂]_n[Al{OC(CF₃)₃}₄]_n ( 4 ), the crystal structure of which differs from that of polymer 2 in the coordination mode of the cyclo‐P₃ ligands: in 2 , the Ag⁺ cations are bridged by the cyclo‐P₃ ligands in a η¹:η¹ (edge bridging) fashion whereas in 4 , they are bridged exclusively in a η²:η¹ mode (face bridging). Thus, one third of the phosphorus atoms in 2 are not coordinated to silver while in 4 , all phosphorus atoms are engaged in coordination with silver. Comprehensive spectroscopic and analytical measurements revealed that the polymers 2 , 3a , b , and 4 depolymerize extensively upon dissolution and display dynamic behavior in solution, as evidenced in particular by variable temperature ³¹P NMR spectroscopy. Solid‐state ³¹P magic angle spinning (MAS) NMR measurements, performed on the polymers 2 , 3b , and 4 , demonstrated that the polymers 2 and 3b also display dynamic behavior in the solid state at room temperature. The X‐ray crystallographic characterisation of 1b is also reported.     

The System LiSO3CF3/RbSO3CF3: Phase Diagram,Solid State NMR Investigations,and Ionic Conductivity

In the system LiSO₃CF₃/RbSO₃CF₃ four different quasi‐ternary phases occur: Li_0.7Rb_0.3SO₃CF₃, Li_0.55Rb_0.45SO₃CF₃, LiRb₂(SO₃CF₃)₃, and Li_0.2Rb_0.8SO₃CF₃. These have been identified, and characterized by means of X‐ray powder diffractometry and DSC. LiSO₃CF₃ is trimorphic, LiRb₂(SO₃CF₃)₃ is dimorphic and RbSO₃CF₃ exists in four different modifications. The cation dynamics has been studied using ⁷Li‐NMR line shape analysis and ⁷Li‐spin lattice relaxation (T₁) measurements. The pure and mixed trifluoromethylsulfonates in the system LiSO₃CF₃/RbSO₃CF₃ are solid electrolytes. Their ionic conductivities below 475 K increase with the rubidium content. Above this temperature, the conductivity of β‐LiRb₂(SO₃CF₃)₃ exceeds the one of δ‐RbSO₃CF₃.     

Snapshots of the Hydrolysis of the Lithium Alkoxide [Li{OC(CF3)3}]4

Exposure of the tetrameric, heterocubane‐like perfluorinated lithium alkoxide [Li{OC(CF₃)₃}]₄ to humid air gaverise to the hydrolysis products [{(CF₃)₃CO}Li(H₂O)₂‐μ‐(H₂O)‐Li(H₂O)₂{OC(CF₃)₃}], [{(CF₃)₃CO}Li(H₂O)₂‐μ‐(H₂O)‐Li‐(H₂O)₃]⁺[OC(CF₃)₃]^– and [Li(H₂O)₄]⁺[OC(CF₃)₃]^– because of stepwise addition of water molecules in a gas‐solid reaction without solvent. All compounds were studied by X‐ray crystallography and their solid‐state structures are strongly influenced by hydrogen bonding and fluorophilic interactions.     

Chiral Fluorinated α‐Sulfonyl Carbanions: Enantioselective Synthesis and Electrophilic Capture,Racemization Dynamics,and Structure

Enantiomerically pure triflones R¹CH(R²)SO₂CF₃ have been synthesized starting from the corresponding chiral alcohols via thiols and trifluoromethylsulfanes. Key steps of the syntheses of the sulfanes are the photochemical trifluoromethylation of the thiols with CF₃Hal (Hal=halide) or substitution of alkoxyphosphinediamines with CF₃SSCF₃. The deprotonation of RCH(Me)SO₂CF₃ (R=CH₂Ph, iHex) with nBuLi with the formation of salts [RC(Me)? SO₂CF₃]Li and their electrophilic capture both occurred with high enantioselectivities. Displacement of the SO₂CF₃ group of (S)‐MeOCH₂C(Me)(CH₂Ph)SO₂CF₃ (95 % ee) by an ethyl group through the reaction with AlEt₃ gave alkane MeOCH₂C(Me)(CH₂Ph)Et of 96 % ee. Racemization of salts [R¹C(R²)SO₂CF₃]Li follows first‐order kinetics and is mainly an enthalpic process with small negative activation entropy as revealed by polarimetry and dynamic NMR (DNMR) spectroscopy. This is in accordance with a C_α? S bond rotation as the rate‐determining step. Lithium α‐(S)‐trifluoromethyl‐ and α‐(S)‐nonafluorobutylsulfonyl carbanion salts have a much higher racemization barrier than the corresponding α‐(S)‐tert‐butylsulfonyl carbanion salts. Whereas [PhCH₂C(Me)SO₂tBu]Li/DMPU (DMPU = dimethylpropylurea) has a half‐life of racemization at ?105 °C of 2.4 h, that of [PhCH₂C(Me)SO₂CF₃]Li at ?78 °C is 30 d. DNMR spectroscopy of amides (PhCH₂)₂NSO₂CF₃ and (PhCH₂)N(Ph)SO₂CF₃ gave N? S rotational barriers that seem to be distinctly higher than those of nonfluorinated sulfonamides. NMR spectroscopy of [PhCH₂C(Ph)SO₂R]M (M=Li, K, NBu₄; R=CF₃, tBu) shows for both salts a confinement of the negative charge mainly to the C_α atom and a significant benzylic stabilization that is weaker in the trifluoromethylsulfonyl carbanion. According to crystal structure analyses, the carbanions of salts {[PhCH₂C(Ph)SO₂CF₃]Li? L }₂ ( L =2 THF, tetramethylethylenediamine (TMEDA)) and [PhCH₂C(Ph)SO₂CF₃]NBu₄ have the typical chiral C_α? S conformation of α‐sulfonyl carbanions, planar C_α atoms, and short C_α? S bonds. Ab initio calculations of [MeC(Ph)SO₂tBu]^? and [MeC(Ph)SO₂CF₃]^? showed for the fluorinated carbanion stronger n_C→σ* and n_O→σ* interactions and a weaker benzylic stabilization. According to natural bond orbital (NBO) calculations of [R¹C(R²)SO₂R]^? (R=tBu, CF₃) the n_C→σ*_{S? R} interaction is much stronger for R=CF₃. Ab initio calculations gave for [MeC(Ph)SO₂tBu]Li ? 2 Me₂O an O,Li,C_α contact ion pair (CIP) and for [MeC(Ph)SO₂CF₃]Li ? 2 Me₂O an O,Li,O CIP. According to cryoscopy, [PhCH₂C(Ph)SO₂CF₃]Li, [iHexC(Me)SO₂CF₃]Li, and [PhCH₂C(Ph)SO₂CF₃]NBu₄ predominantly form monomers in tetrahydrofuran (THF) at ?108 °C. The NMR spectroscopic data of salts [R¹(R²)SO₂R³]Li (R³=tBu, CF₃) indicate that the dominating monomeric CIPs are devoid of C_α? Li bonds.     

Kristallstruktur eines Lithiumsilylamidbutanids

Crystal Structure of a Lithiumsilylamidebutanide Colorless single crystals of {Li₆[Me₂(H)Si—N—Si(H)—(CHMe₂)₂]₂[n‐C₄H₉]₄} ( 1 ) were obtained from a solution of Me₂(H)SiN(Li)Si(H)(CHMe₂)₂ and n‐C₄H₉Li in n‐hexane. The X‐ray analysis showed that the core of 1 is a distorted octahedron of lithium atoms with ten long and with two short LiÄLi distances. Four of the eight triangular Li₃ faces are capped by an n‐butyl group. The nitrogen atoms of the amide groups are situated about opposite edges of adjacent unoccupied Li₃ faces. (Si)H····Li interactions exist between the hydridic H atom of each Me₂(H)Si group and one Li atom.     

Cationic versus neutral Ru(II)--N-heterocyclic carbene complexes as latent precatalysts for the UV-induced ring-opening metathesis polymerization

A series of cationic and neutral Ru^II complexes of the general formula [Ru(L)(X) (tBuCN)₄]⁺X^? and [Ru(L)(X)₂(tBuCN)₃)], that is, [Ru(CF₃SO₃){NCC(CH₃)₃}₄(IMesH₂)]⁺[CF₃SO₃]^? ( 1 ), [Ru(CF₃SO₃){NCC(CH₃)₃}₄(IMes)]⁺[CF₃SO₃]^? ( 2 ), [RuCl{NCC(CH₃)₃}₄(IMes)]⁺Cl^? ( 3 ), [RuCl{NCC(CH₃)₃}₄(IMesH₂)⁺Cl^?]/[RuCl₂{NCC(CH₃)₃}₃(IMesH₂)] ( 4 ), and [Ru(NCO)₂{NCC(CH₃)₃}₃(IMesH₂)] ( 5 ) (IMes=1,3‐dimesitylimidazol‐2‐ylidene, IMesH₂=1,3‐dimesityl‐imidazolin‐2‐ylidene) have been synthesized and used as UV‐triggered precatalysts for the ring‐opening metathesis polymerization (ROMP) of different norborn‐2‐ene‐ and cis‐cyclooctene‐based monomers. The absorption maxima of complexes 1 – 5 were in the range of 245–255 nm and thus perfectly fit the emission band of the 254 nm UV source that was used for activation. Only the cationic Ru^II‐complexes based on ligands capable of forming μ²‐complexes such as 1 and 2 were found to be truly photolatent in ROMP. In contrast, complexes 3 – 5 could be activated by UV light; however, they also showed a low but significant ROMP activity in the absence of UV light. As evidenced by ¹H and ¹³C NMR spectroscopy, the structure of the polymers obtained with either 1 or 2 are similar to those found in the corresponding polymers prepared by the action of [Ru(CF₃SO₃)₂(IMesH₂)(CH‐2‐(2‐PrO)‐C₆H₄)], which strongly suggest the formation of Ru‐based Grubbs‐type initiators in the course of the UV‐based activation process. Precatalysts that have the IMesH₂ ligand showed significantly enhanced reactivity as compared with those based on the IMes ligand, which is in accordance with reports on the superior reactivity of IMesH₂‐based Grubbs‐type catalysts compared with IMes‐based systems.     

Reaction of aryl azides with tris(trimethylsilyl)silyllithium: Synthesis of tmeda or thf adducts of [Li{N(Ar)Si(SiMe3)3}] and 1,4-trimethylsilyl migration from oxygen to nitrogen

Reaction of ArN₃ (Ar = Ph, p-MeC₆H₄, 1-naphthyl) with [Li{Si(SiMe₃)₃}(thf)₃] yielded lithium amides [Li{N(Ar)Si(SiMe₃)₃}L] (L = tmeda or (thf)₂). Similar treatment of o-phenylene diazide with 2 equiv. of [Li{Si(SiMe₃)₃}(thf)₃] formed dilithium diamide complex 4. Reaction between o-Me₃SiOC₆H₄N₃ and [Li{Si(SiMe₃)₃}(thf)₃] afforded, via 1,4-trimethylsilyl migration from oxygen to nitrogen, [Li{OC₆H₄{N(SiMe₃)Si(SiMe₃)₃}-2}]₂ (5). The structures of complexes 3 and 5 have been determined by single crystal X-ray diffraction techniques.     

Cerium(III/IV) Formamidinate Chemistry,and a Stable Cerium(IV) Diolate

Four new cerium(III) formamidinate complexes comprising [Ce(p‐TolForm)₃], [Ce(DFForm)₃(thf)₂], [Ce(DFForm)₃], and [Ce(EtForm)₃] were synthesized by protonolysis reactions using [Ce{N(SiMe₃)₂}₃] and formamidines of varying functionality, namely N,N′‐bis(4‐methylphenyl)formamidine (p‐TolFormH), N,N′‐bis(2,6‐difluorophenyl)formamidine (DFFormH), and the sterically more demanding N,N′‐bis(2,6‐diethylphenyl)formamidine (EtFormH). The bimetallic cerium lithium complex [LiCe(DFForm)₄] was synthesized by treating a mixture of [Ce{N(SiHMe₂)₂}₃(thf)₂] and [Li{N(SiHMe₂)₂}] with four equivalents of DFFormH in toluene. Oxidation of the trivalent cerium(III) formamidinate complexes by trityl chloride (Ph₃CCl) caused dramatic color changes, although the cerium(IV) species appeared transient and reformed cerium(III) complexes and N′‐trityl‐N,N′‐diarylformamidines shortly after oxidation. The first structurally characterized homoleptic cerium(IV) formamidinate complex [Ce(p‐TolForm)₄] was obtained through a protonolysis reaction between [Ce{N(SiHMe₂)₂}₄] and four equivalents of p‐TolFormH. [Ce{N(SiHMe₂)₂}₄] was also treated with DFFormH and EtFormH, but the resulting cerium(IV) complexes decomposed before isolation was possible. The new cerium(IV) silylamide complex [Ce{N(SiMe₃)₂}₃(bda)_0.5]₂ (bda=1,4‐benzenediolato) was synthesized by treatment of [Ce{N(SiMe₃)₂}₃] with half an equivalent of 1,4‐benzoquinone, and showed remarkable resistance towards protonolysis or reduction.     

[{ReN(PMe2Ph)3}{ReO3N}]2 – Structural Evidence for the Nitridotrioxorhenate(VII) Anion, [ReO3N]2−

Air‐stable, orange‐red single crystals of [{ReN(PMe₂Ph)₃}{ReO₃N}]₂ are formed when mer‐[ReNCl₂(PMe₂Ph)₃] reacts with strong bases in MeOH. The resulting centrosymmetric tetranuclear complex contains each two {ReN(PMe₂Ph)₃}²⁺ and {ReO₃N}^2? building blocks. They are connected by two oxygen and two nitrogen atoms giving an almost planar {Re₄O₂N₂} ring. The Re–N–Re bridges are only slightly bent (175.2(2)°), while the Re–O–Re angles are 160.9(1)°. The coordination environment of the rhenium atom in the nitridotrioxorhenate(VII) anion is a slightly distorted tetrahedron with O–Re–O and O–Re–N angles between 108.7(1)° and 111.3(1)°.     

Twinned α‐LiRb2(CF3SO3)3

The investigated crystal of α‐LiRb₂(CF₃SO₃)₃ [lithium dirubidium tris­(tri­fluoro­methane­sulfonate)] was a twin, with the twin matrix given by (00/010/001). The structure consists of channel‐like patterns built up of lipophilic CF₃ groups pointing towards each other. The polar interstices are occupied by cations. One Rb atom is coordinated by O atoms in the form of a distorted square antiprism, while the coordination around the second Rb atom is best described as a distorted pentagonal plane, with one O atom and one F atom situated above and an additional F atom below this plane. The O atoms around the Li atom form a strongly distorted tetrahedron.     

The Parent Cyclopentadienyltin Cation,Its Toluene Adduct,and the Quadruple‐Decker [Sn3Cp4]2+

Truly cationic metallocenes with the parent cyclopentadienyl ligand are so far unknown for the Group 14 elements. Herein we report on an almost “naked” [SnCp]⁺ cation with the weakly coordinating [Al{OC(CF₃)₃}₄]⁻ and [{(F₃C)₃CO}₃Al−F−Al{OC(CF₃)₃}₃]⁻ anions. [SnCp][Al{OC(CF₃)₃}₄] was used to prepare the first main‐group quadruple‐decker cation [Sn₃Cp₄]²⁺ again as the [Al{OC(CF₃)₃}₄]⁻ salt. Additionally, the toluene adduct [CpSn(C₇H₈)][Al{OC(CF₃)₃}₄] was obtained.