Reactions of Alk‐1‐enylxenonium(II) and Alk‐1‐ynylxenonium(II) Salts [RXe]Y with Bromides and Iodides in Anhydrous HF

The replacement of xenon(+) by iodine in reactions of alkenylxenonium(II) salts [RCF=CFXe]Y (R = cis-C₂F₅, trans-H) and alkynylxenonium(II) salt [C₃F₇C≡CXe][BF₄] with NaI in anhydrous HF (aHF) occurred regiospecifically. At −60 °C the substitution of xenon(+) by bromine in the perfluorinated salts [cis-CF₃CF=CFXe]Y and [trans-C₄F₉CF=CFXe]Y proceeded regio- and stereospecifically with NaBr in aHF, but at a higher temperature and after a longer time the treatment of [cis-C₂F₅CF=CFXe]Y with NaBr, KBr, or [NBu₄]Br in aHF gave mixtures of cisand trans-perfluorobut-1-enyl bromides. The reaction of [C₃F₇C≡CXe][BF₄] with NaBr in aHF at −65 °C gave only 48 %, of C₃F₇C≡CBr and was accompanied by a mixture of bromine-containing related olefins. Reaction pathways to the main product are discussed.     

Synthesis and Spectroscopic Characterization of Potassium Polyfluoroalken‐1‐yltrifluoroborates

The potassium fluoroborates K[RCF=CFBF₃] (R = F, Cl (cis‐/trans‐mixture), trans‐C₄F₉, cis‐C₂F₅, cis‐C₆F₁₃, trans‐C₄H₉, trans‐C₆H₅) were prepared by fluoridation (methoxide‐fluoride substitution with K[HF₂]) of RCF=CFB(OMe)₂ and Li[RCF=CFB(OMe)₃] which were obtained from RCF=CFLi and B(OMe)₃. The K[RCF=CFBF₃] salts were characterized by their ¹H, ¹¹B, ¹⁹F NMR and IR spectra.     

The Reactivity of Potassium Polyfluoroaryl‐, Polyfluoroalkenyl‐, and Perfluoroalkyltrifluoroborates and their Hydrocarbon Analogues towards Acids of Different Strength: A Systematic Study of the Hydrodeboration

The hydrodeboration of the (fluoroorgano)trifluoroborates K [R_FBF₃] [R_F = C₆F₅, XCF=CF (X = F, cis‐ and trans‐Cl, C₃F₇O, cis‐C₂F₅, trans‐C₄F₉, ‐C₄H₉) and C₆F₁₃] and of the organotrifluoroborates K [RBF₃] (R = C₆H₅, cis‐ and trans‐C₄H₉CH=CH, C₄H₉ and C₈H₁₇) with CH₃CO₂H (100 %), CF₃CO₂H (100 %), aqueous HF and anhydrous HF was investigated. In the alkenyltrifluoroborates K [R'CF=CFBF₃] the formal replacement of BF₃ by a proton occurred stereospecifically under retention of the configuration. The ¹⁹F NMR spectra of K [R_FBF₃] in acids indicate strong interactions of the BF₃ group with protons or acid molecules.     

The Reaction of 2‐X‐1, 2‐Difluoroalk‐1‐enyldifluoroboranes with Xenon Difluoride. A Methodical Approach to 1, 2‐Difluoroalk‐1‐enylxenon(II) Salts

2‐X‐1, 2‐Difluoroalk‐1‐enylxenon(II) salts were prepared by the reaction of XeF₂ with XCF=CFBF₂ (X = F, trans‐H, cis‐Cl, trans‐Cl, cis‐CF₃, cis‐C₂F₅) but no organoxenon(II) compounds were obtained when the trans‐isomers of boranes, trans‐XCF=CFBF₂ (X = CF₃, C₄F₉, C₄H₉, Et₃Si), were used under similar conditions.     

Die thermische Umlagerung von 2-(Buta-1′,3′-dienyl)-phenolen in 2-Alkyl-2H-chromene; Beispiele für aromatische [1,7a]- und [1,5s]sigmatropische Wasserstoffverschiebungen

2-(1′-cis,3′-cis-)- and 2-(1′-cis,3′-trans-Penta-1′,3′-dienyl)-phenol (cis, cis- 4 and cis, trans- 4 , cf. scheme 1) rearrange thermally at 85–110° via [1,7 a] hydrogen shifts to yield the o-quinomethide 2 (R ? CH₃) which rapidly cyclises to give 2-ethyl-2H-chromene ( 7 ). The trans formation of cis, cis- and cis, trans- 4 into 7 is accompanied by a thermal cis, trans isomerisation of the 3′ double bond in 4. The isomerisation indicates that [1,7 a] hydrogen shifts in 2 compete with the electrocyclic ring closure of 2 . The isomeric phenols, trans, trans- and trans, cis- 4 , are stable at 85–110° but at 190° rearrange also to form 7 . This rearrangement is induced by a thermal cis, trans isomerisation of the 1′ double bond which occurs via [1, 5s] hydrogen shifts. Deuterium labelling experiments show that the chromene 7 is in equilibrium with the o-quinomethide 2 (R ? CH₃), at 210°. Thus, when 2-benzyl-2H-chromene ( 9 ) or 2-(1′-trans,3′-trans,-4′-phenyl-buta1′,3′-dienyl)-phenol (trans, trans- 6 ) is heated in diglyme solution at >200°, an equilibrium mixture of both compounds (～ 55% 9 and 45% 6 ) is obtained.     

(Fluoroorgano)fluoroboranes and ‐borates. 7 [1] The Reaction of RFBF2 and K [RFBF3] (RF = perfluorophenyl‐, perfluoroalk‐1‐enyl‐ and perfluoroalkyl) with Xenon Difluoride in Anhydrous HF

The dissolution of (perfluoroorgano)difluoroboranes R_FBF₂ in anhydrous HF (aHF) resulted in equilibrium mixtures of the starting borane and different kinds of acid‐base products: [H₂F] [R_FBF₂(F · HF)] (R_F = C₆F₅, cis‐C₂F₅CF=CF, trans‐C₄F₉CF=CF) or [H₂F] [R_FBF₃] (R_F = C₆F₁₃). In aHF the aryl compounds C₆F₅BF₂ and K [C₆F₅BF₃] showed two parallel reactivities with XeF₂: xenodeborylation (formation of the [C₆F₅Xe]⁺ cation) and fluorine addition to the aryl group. In aHF perfluoroalk‐1‐enyldifluoroboranes R_FBF₂ as well as potassium perfluoroalk‐1‐enyltrifluoroborates K [R_FBF₃] (R_F = cis‐C₂F₅CF=CF, trans‐C₄F₉CF=CF) underwent only fluorine addition across the carbon‐carbon double bond under the action of XeF₂. Potassium perfluorohexyltrifluoroborate K [C₆F₁₃BF₃] did not react with XeF₂ in aHF.     

Thermal isomerization of ruthenium hydride compounds containing asymmetric bidentate pyrrole‐imine ligands

A series of ruthenium hydride compounds containing substituted bidentate pyrrole‐imine ligands were synthesized and characterized. Reacting RuHCl(CO)(PPh₃)₃ with one equivalent of [C₄H₃NH(2‐CH=NR)] in ethanol in the presence of KOH gave compounds {RuH(CO)(PPh₃)₂[C₄H₃N(2‐CH=NR)]} where trans‐Py‐Ru‐H 1, R = CH₂CH₂C₆H₉; cis‐Py‐Ru‐H 2, R = Ph‐2‐Me; and cis‐Py‐Ru‐H 3, R = C₆H₁₁. Heating trans‐Py‐Ru‐H 1 in toluene at 70°C for 12 hr resulted a thermal conversion of the trans‐Py‐Ru‐H 1 into its cis form, {RuH(CO)(PPh₃)₂[C₄H₃N(2‐CH=NCH₂CH₂C₆H₉)]} (cis‐Py‐Ru‐H 1) in very high yield. The ¹H NMR spectra of trans‐Py‐Ru‐H 1, cis‐Py‐Ru‐H 2, cis‐Py‐Ru‐H 3, and cis‐Py‐Ru‐H 1 all show a typical triplet at ca. δ–11 for the hydride. The trans and cis form indicate the relative positions of pyrrole ring and hydride. The geometries of trans‐Py‐Ru‐H 1, cis‐Py‐Ru‐H 1, and cis‐Py‐Ru‐H 3 are relatively similar showing typical octahedral geometries with two PPh₃ fragments arranged in trans positions.     

Syntheses of Unique Bicyclophostones and Unexpected Difference in the Reaction of Lawesson's Reagent vs. P2S5 with Cis-Bicyclophostone (1)

Abstract

The purpose of this study was to synthesize trans-l and determine the equilibriurr constant with cis-1. Oniy the synthesis¹ and x-ray structure² of the cis isomer have bcen reported. Four prior synthetic routes to make the vans isomer³ gave only cis product. For example, intrarmolecular ring closure of the cis or trains isomers of 4 (R= (CH₂)₃OH) with LiH or thermal closure of the cis or trans 4 (R= (CH₂)₂) gave only cis-1. Since both iosmers of 1,8-dioxabicyclo[4.4.0] decane are known and readily equilibrate (57% cis and 43% trans), the apparent inaccessibility of trans-1 attracted our attention. Thc preparation of trans-1 was achieved by treatment of cis-1 with Lawesson's reagent (LR) to provide cis-2. followed by oxidation with m-chloroperbenzoic acid/trifluoroacetic acid to give a 5:1 mixture of cis:trans 1, respectively. An unexpected formation of the sulfur analogue of 1 was observed on treatment of cis-1 with P₂S₅/pyridine at reflux temperatures to give a 1.6:1 mixture of cis:trans 3, respectively. Thermal quilibration of 1 at 204°C provided an equilibrium ratio of 99.5% cis and 0.5% of the trans isomer. However, equilibration of 3 at 250°C led to 82.2:17.8 ratio in favor of the cis isomr. These results are consistent with semiemperical MO calculations. The stereochemical outcome on treatment of 4 with LR was also investigated. X-ray structures for six compounds: trans-1, cis-2, cis and trans-3; cis-4 (R=Ph), and cis-5, (R = Ph) wen determined.     

Redox Non‐Innocence and Isomer‐Specific Oxidative Functionalization of Ruthenium‐Coordinated β‐Ketoiminate

This article deals with isomeric ruthenium complexes [Ru^III(L^R)₂(acac)] (S=1/2) involving unsymmetric β‐ketoiminates (AcNac) (L^R=R‐AcNac, R=H ( 1 ), Cl ( 2 ), OMe ( 3 ); acac=acetylacetonate) [R=para‐substituents (H, Cl, OMe) of N‐bearing aryl group]. The isomeric identities of the complexes, cct (cis‐cis‐trans, blue, a ), ctc (cis‐trans‐cis, green, b ) and ccc (cis‐cis‐cis_, pink, c ) with respect to oxygen (acac), oxygen (L) and nitrogen (L) donors, respectively, were authenticated by their single‐crystal X‐ray structures and spectroscopic/electrochemical features. One‐electron reversible oxidation and reduction processes of 1 – 3 led to the electronic formulations of [Ru^III(L)(L ^? )(acac)]⁺ and [Ru^II(L)₂(acac)]^? for 1 ⁺‐ 3 ⁺ (S=1) and 1^? – 3^? (S=0), respectively. The triplet state of 1 ⁺‐ 3 ⁺ was corroborated by its forbidden weak half‐field signal near g≈4.0 at 4 K, revealing the non‐innocent feature of L. Interestingly, among the three isomeric forms ( a – c in 1 – 3 ), the ctc ( b in 2 b or 3 b ) isomer selectively underwent oxidative functionalization at the central β‐carbon (C?H→C=O) of one of the L ligands in air, leading to the formation of diamagnetic [Ru^II(L)(L ′ )(acac)] (L ′ =diketoimine) in 4 / 4′ . Mechanistic aspects of the oxygenation process of AcNac in 2 b were also explored via kinetic and theoretical studies.     

Structure and Photochemical Properties of r‐1, c‐2, t‐3, t‐4‐l, 3‐Bis [2‐ (5‐R‐benzoxazolyl) ] −2,4‐di (4‐R' ‐phenyl) cyclobutane

r‐1, c‐2, t‐3, t‐4‐1,3‐Bis[2‐(5‐R‐benzoxazolyl)]‐2,4‐di(4‐R'‐phenyl)cyclobutane (IIa: R=R' = H; IIb: R=Me, R'= H; IIc: R = Me, R' = OMe) was synthesized with high stereo‐selectivity by the photodimerization of trans‐l‐[2‐(5‐R‐benzoxazolyl)]‐2‐(4‐R'‐phenyl) ethene (Ia: R=R' = H; Ib: R = Me, R' = H; Ic: R = Me, R' = OMe) in sulfuric acid. The structures of IIa–IIc were identified by elemental analysis, IR, UV, ¹H NMR, ¹³C NMR and MS. The molecular and crystal structure of IIc has been determined by X‐ray diffraction method. The crystal of IIc (C₃₄H₃₀N₂O₄. 0.5C₂OH) is monoclinic, space group P2₁/n with cell dimensions of a = 1.5416(3), b =0.5625(1), c = 1.7875(4) nm, β = 91.56 (3)°, V= 1.550(1) nm³, Z = 2. The structure shows that the molecule of IIc is centrosymmetric, which indicates that the dimerization process is a head‐to‐tail fashion. The selectivity of the photodimerization of Ia–Ic has been enhanced by using acidic solvent and the reaction speed would be decreased when electron donating group was introduced in the 4‐position of the phenyl group. That the photodimerization is not affected by the presence of oxygen as well as its high stereo‐selectivity demonstrated that the reaction proceeded through an excited singlet state. It was also found that under irradiation of short wavelength UV, these dimers underwent photolysis completely to reproduce its trans‐monomers, and then the new formed species changed into their cis‐isomers through trans‐cis isomerization.     

Cyclopolymerization of 1,5‐hexadiene catalyzed by various stereospecific metallocene compounds

Cyclopolymerization of 1,5‐hexadiene has been carried out at various temperatures in toluene by using three different stereospecific metallocene catalysts—isospecific rac‐(EBI)Zr(NMe₂)₂ [EBI: ethylenebis(1‐indenyl), Cat 1], syndiospecific Me₂C(Cp)(Flu)ZrMe₂ (Cp = 1‐cyclopentadienyl, Flu = 1‐fluorenyl, Cat 2), and aspecific CpZrMe₂ (Cp*: pentamethylcyclopentadienyl, Cat 3) compounds in the presence of Al(i‐Bu)₃ and [Ph₃C][B(C₆F₅)₄]—in order to study the effect of polymerization temperature and catalyst stereospecificity on the property and microstructure of poly(methylene‐1,3‐cyclopentane) (PMCP). The activities of catalysts decrease in the following order: Cat 1 > Cat 2 > Cat 3. PMCPs produced by Cat 1 are not completely soluble in toluene, but those by Cat 2 and Cat 3 are soluble in toluene. trans‐Diisotactic rich PMCPs are produced by Cat 1 and Cat 2, and cis‐atactic PMCP by Cat 3. The cis/trans ratio of PMCP by Cat 1 and Cat 2 is relatively insensitive to the polymerization temperature, but that by Cat 3 is highly sensitive to the polymerization temperature. Melting temperatures of PMCP produced increase with the cis to trans ratio of rings. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1520–1527, 2000     

The unusual reactivity of C3F7OCFCF2 with PBu3 and the complex hydrides M[EH4] (M: Li, Na; E: B, Al); preparation of potassium perfluoro-2-propoxyeth-1-enyltrifluoroborate K[C3F7OCFCFBF3]

The nucleophilic hydrodefluorination of C₃F₇OCFCF₂ with the complex hydrides Li[AlH₄], Li[BH₄] or Na[BH₄] proceeded non-stereoselectively and was accompanied by the formation of either cis- and trans-C₃F₇OCHCFH and/or C₃F₇OCHFCF₂H. The reaction of C₃F₇OCFCF₂ with PBu₃ followed by treatment with BF₃·OMe₂ or BF₃·OEt₂ yielded [C₃F₇OCFCFPBu₃] [BF₄] (cis and trans) and, probably, [trans-Bu₃PCFCFPBu₃] [BF₄]₂. The hydrolysis of the latter with pure water proceeded quickly while the former isomeric mixture formed the isomeric olefins C₃F₇OCFCFH slowly. The usage of aqueous NaOH instead of water produced mainly trans-CHFCHF. The metallation of C₃F₇OCFCFH (cis:trans=45:55) to C₃F₇OCFCFLi and its subsequent reaction with B(OMe)₃ and K[HF₂] gave the salt K[C₃F₇OCFCFBF₃] in a different cis to trans ratio (25:75) with satisfactory yield.     

Tridentate Lewis Acids Based on 1,3,5‐Trisilacyclohexane Backbones and an Example of Their Host–Guest Chemistry

Directed tridentate Lewis acids based on the 1,3,5‐trisilacyclohexane skeleton with three ethynyl groups [CH₂Si(Me)(C₂H)]₃ were synthesised and functionalised by hydroboration with HB(C₆F₅)₂, yielding the ethenylborane {CH₂Si(Me)[C₂H₂B(C₆F₅)₂]}₃, and by metalation with gallium and indium organyls affording {CH₂Si(Me)[C₂M(R)₂]}₃ (M=Ga, In, R=Me, Et). In the synthesis of the backbone the influence of substituents (MeO, EtO and iPrO groups at Si) on the orientation of the methyl group was studied with the aim to increase the abundance of the all‐cis isomer. New compounds were identified by elemental analyses, multi‐nuclear NMR spectroscopy and in some cases by IR spectroscopy. Crystal structures were obtained for cis‐trans‐[CH₂Si(Me)(Cl)]₃, all‐cis‐[CH₂Si(Me)(H)]₃, all‐cis‐[CH₂Si(Me)(C₂H)]₃, cis‐trans‐[CH₂Si(Me)(C₂H)]₃ and all‐cis‐[CH₂Si(Me)(C₂SiMe₃)]₃. A gas‐phase electron diffraction experiment for all‐cis‐[CH₂Si(Me)(C₂H)]₃ provides information on the relative stabilities of the all‐equatorial and all‐axial form; the first is preferred in both solid and gas phase. The gallium‐based Lewis acid {CH₂Si(Me)[C₂Ga(Et)₂]}₃ was reacted with a tridentate Lewis base (1,3,5‐trimethyl‐1,3,5‐triazacyclohexane) in an NMR titration experiment. The generated host–guest complexes involved in the equilibria during this reaction were identified by DOSY NMR spectroscopy by comparing measured diffusion coefficients with those of the suitable reference compounds of same size and shape.     

Neutral and anionic pentafluorophenyl complexes of palladium and platinum(II) and their reactivity towards amines

Summary The (n-Bu₄N)[M(C₆F₅)₃(CNR)] complexes (M=Pd or Pt; R=p-Tolyl, Me, Cy ort-Bu, prepared from (n-Bu₄N)[M(C₆F₅)₃(tht)] (tht = tetrahydrothiophene) and the appropriate isocyanide, RNC, prove to be unreactive towards benzylamine or MeOH. Thetrans-[Pd(C₆F₅)₂(CNR)₂] complexes react slowly with benzylamine to give the corresponding carbene complexestrans-[Pd(C₆F₅)₂{C(NHR)(NHBz)}₂], the rate of the reaction decreasing in the order:p-Tolyl > Me > Cy t-Bu (for R=t-Bu the carbene complex cannot be prepared). In the corresponding Pt complexes a marked decrease in reactivity is observed and only the most reactive isonitrile complex (R=p-Tolyl) gives the carbene complextrans-[Pt(C₆F₅)₂{C(NHTolyl-p)(NHBz)}_2}. Thecis-[M(C₆F₅)₂(CNTolyl)₂] complexes do not show any change in reactivity compared to the correspondingtrans-complexes, and givecis[M(C₆F₅)₂{C(NHTolyl-p)(NHBz)}₂].     

Hydrogallierungsreaktionen mit den Monoalkinen H5C6‐C≡C‐SiMe3 und H5C6‐C≡C‐CMe3 – cis/trans‐Isomerie und Substituentenaustausch

Hydrogallation Reactions Involving the Monoalkynes H₅C₆‐C≡C‐SiMe₃ and H₅C₆‐C≡C‐CMe₃ – cis/trans Isomerisation and Substituent Exchange Phenyl‐trimethylsilylethyne, H₅C₆‐C≡C‐SiMe₃, reacted with different dialkylgallium hydrides, R₂Ga‐H (R = Me, Et, nPr, iPr, tBu), by the addition of one Ga‐H bond to its C≡C triple bond (hydrogallation). The gallium atoms attacked selectively those carbon atoms, which were also attached to trimethylsilyl groups. The cis arrangement of Ga and H across the resulting C=C double bonds resulted only for the sterically most shielded di(tert‐butyl)gallium derivative, while in all other cases spontaneous cis/trans rearrangement occurred with the quantitative formation of the trans addition products. The diethyl compound Et₂Ga‐C(SiMe₃)=C(H)‐C₆H₅ ( 2 ) gave by substituent exchange the secondary products EtGa[C(SiMe₃)=C(H)‐C₆H₅]₂ ( 7 , Z,Z) and Ga[C(SiMe₃)=C(H)‐C₆H₅]₃ ( 8 ). Interestingly, compound 8 has two alkenyl groups with a Z configuration, while the third C=C double bond has the cis arrangement of Ga and H (E configuration). The reversibility of the cis/trans isomerisation of hydrogallation products was observed for the first time. tert‐Butyl‐phenylethyne gave the simple addition product, R₂Ga(C₆H₅)=C(H)‐CMe₃ ( 9 ), only with di(n‐propyl)gallium hydride.     

π‐Facial selectivities of diastereotopic ketones: p‐bromobenzoates of 4‐hetero‐1‐decalinols

The crystal structures of the p‐bromo­benzoates of cis‐4‐oxa‐1‐decalinyl (C₁₆H₁₉BrO₃), trans‐4‐oxa‐1‐decalinyl (C₁₆H₁₉­BrO₃), N‐benzyl‐cis‐4‐aza‐1‐decalinyl (C₂₃H₂₆BrNO₂), N‐benzyl‐trans‐4‐aza‐1‐decalinyl (C₂₃H₂₆BrNO₂) and trans‐4‐thia‐1‐decalinyl (C₁₆H₁₉BrO₂S) (decalin is per­hydro­naphthalene) have been determined as part of a study directed at predicting and interpreting the π‐facial selectivities of diastereotopic ketones in reactions with nucleophiles. All five structures are composed of mol­ecules that are separated by normal van der Waals distances. In all five structures, the heterocyclic and cyclo­hexyl rings adopt chair conformations, and the p‐bromo­benzoate groups are planar.     

Synthesis and Reactivity of Iridium(I) Fluorido Complexes: Oxidative Addition of SF4 at trans-[Ir(F)(CO)(PEt3)2]

The facile access to the Vaska type fluorido complexes trans-[Ir(F)(CO)(PR₃)₂] [ 6 : R = Et, 7 : R = Ph, 8 : R = iPr, 9 : R = Cy, 10 : R = tBu] was achieved by halide exchange at trans-[Ir(Cl)(CO)(PR₃)₂] ( 1 – 5 ) with Me₄NF. Furthermore, the reaction of complex 6 with SF₄ gave cis,trans-[Ir(F)₂(SF₃)(CO)(PEt₃)₂] ( 11 ), whereas 8 – 10 did not react. Reactivity studies revealed that 11 can selectively be manipulated at the sulfur atom by hydrolysis or fluoride abstraction to give cis,trans-[Ir(F)₂(SOF)(CO)(PEt₃)₂] ( 12 ) and cis,trans-[Ir(F)₂(SF₂)(CO)(PEt₃)₂][AsF₆] ( 13 ), respectively.     

Fluoroborates by Cleavage of Trimethylamine‐bis(trifluoromethyl)boranes with NEt3 × 3 HF. Structures of C6F5(CF3)2B · NMe3, K[C6H5CH2(CF3)2BF], and K[C6H5(CF3)2BF]

Trimethylamine‐bis(trifluoromethyl)boranes R(CF₃)₂B · NMe₃ (R = cis/trans‐CF₃CF=CF ( 1/2 ), HC≡C ( 3 ), H₂C=CH ( 4 ), C₂H₅ ( 5 ), C₆H₅CH₂ ( 6 ), C₆F₅ ( 7 ), C₆H₅ ( 8 )) react with NEt₃ × 3 HF depending on the nature of R at 155–200 °C under replacement of the trimethylamine ligand to form the corresponding fluoro‐bis(trifluoromethyl)borates [R(CF₃)₂BF]^– ( 1 a/2 a – 8 a ). The structures of 7 , K[C₆H₅CH₂(CF₃)₂BF] ( K‐6 a ), and K[C₆H₅(CF₃)₂BF] ( K‐8 a ) have been investigated by single‐crystal X‐ray diffraction. In 7 the CF₃ groups make short repulsive contacts with NMe₃ and C₆F₅ entities – the B–CF₃ bonds being unusually long. The B–F bond lengths of K‐6 a and K‐8 a (1.446(3) and 1.452(2) Å, respectively) are long for a fluoroborate.     

Synthese und strukturelle Studien von Aluminiumdialkylaminen und ‐amiden: N‐Chiralität von (CH3)3AlNHRR′ und cis‐trans‐Isomerie an X2AlNRR′ (X = CH3, Cl,H)

Synthesis and Structural Studies of Aluminum Dialkylamines and Dialkylamides: N‐Chirality of (CH₃)₃AlNHRR′ and cis‐trans ‐Isomerism at X₂AlNRR′ (X = CH₃, Cl, H) Aluminum dialkylamines and dialkylamides were prepared from Al(CH₃)₃ and NH(CH₃)R′ (R′: –C₂H₅, –^tC₄H₉) and characterized by elemental analyses, ¹H‐, ¹³C‐, and ²⁷Al‐NMR spectroscopy. The crystal structures of [(CH₃)₂AlN(CH₃)(–^tC₄H₉)]₂ ( IV ), [Cl₂AlN(CH₃)(C₂H₅)]₂ ( V ), and [H₂AlN(CH₃)(C₂H₅)]_∞ ( VI‐trans and VI‐cis ) are discussed.     

The Synthesis by Decarboxylation Reactions and Crystal Structures of 1, n–Bis(diphenylphosphino)alkane(pentafluorophenyl)‐platinum(II) Complexes

Decarboxylation reactions between the complexes cis–[PtCl₂L] (L = 1, n–bis(diphenylphosphino)–ethane (n = 2, dppe), –propane (n = 3, dppp) or –butane (n = 4, dppb)) and thallium(I) pentafluorobenzoate in pyridine give cis–[PtCl(C₆F₅)L] and cis–[Pt(C₆F₅)₂L] complexes in high yields with short reaction times. X–ray crystal structures of cis–[PtCl(C₆F₅)(dppe)] · 0.5 C₅H₅N, cis–[PtCl(C₆F₅)(dppp)], cis–[PtCl(C₆F₅)(dppb)] · C₃H₆O, cis–[Pt(C₆F₅)₂L] (L = dppe, dppp and dppb) and the reactants cis–[PtCl₂(dppp)] (as a CH₂Cl₂ solvate) and cis–[PtCl₂(dppb)] show monomeric structures with chelating diphosphine ligands in all cases rather than dimers with bridging diphosphines. ³¹P NMR data are consistent with these structures in solution.