Phenoxyaluminium compounds: VI. Complex and reaction mechanism of methylaluminium compounds with anisole

The reactions of anisole with organoaluminium compounds Me_nAlX_3−n have been investigated.The formation of a complex is the first reaction step, followed by cleavage and elimination of the gases MeX and small amounts of hydrocarbons. The yield of the gases and the cleavage rate decreases in the order: AlCl₃ >/ MeAlCl₂ > Me₂AlCl > Me₃Al and Me₂AlI > Me₂AlCl > Me₂AlBr. For most of the investigated reactions a marked decrease in gas evolution was observed after a short period of time. This is explained by the formation of an almost inactive mixed dimer (I) which at the

reaction temperature is more stable than the Me₂(Cl)Al : O(Me)Ph complex. It is suggested that dimer I is formed after the intramolecular reaction of the 2 : 1 complex II after elimination of MeX.

     

Substitutionsreaktionen der Bis(trimethylelement)carbodiimide des Siliciums und Germaniums mit Metallchloriden und Dimethylmetallchloriden des Sb,Al, Ga und In

Substitution Reactions of Bis(trimethylelement)carbodiimides of Silicon and Germanium with Metal Chlorides and Dimethylmetalchlorides of Sb, Al, Ga, and In The reaction of Me₃Ge? N?C?N? GeMe₃ (Me?CH₃) with SbCl₅ in a 1 : 1 molar ratio forms dimeric Cl₄SbNCNGeMe₃ in high yields. The corresponding compounds (X₂MNCNSiMe₃)_2–3 (with X?Cl, Me and M = Al, Ga), formed by reactions of X₂MCl and Me₃SiNCNSiMe₃, are less stable and tend to condensations, eliminating Me₃SiX. The carbodiimide derivates (Me₂MNCNEMe₃)_2–3 (with E = Si, Ge) are also available in aprotic solvents from polymeric LiNCNEMe₃ and Me₂MCl (M = Al, Ga, In). According to the IR and Raman spectra the low associated substitution products consists of cyclic ring skeletons and asymmetric > N? C?N? EMe₃ units with cyanamide conformation.     

Trimethylstannyl- und Dimethylstannyl-substituierte Pyrrole – Synthesen,Spektren und Strukturen

Trimethylstannyl- and Dimethylstannyl-substituted Pyrroles – Synthesis, Spectra, and Structures Monomeric trimethylstannyl pyrroles, Me₃Sn? R (Me = CH₃ and R = ? NC₄H₄, ? NC₄H₂Me₂-2,5, ? NC₄Me₄-2,3,4,5, ? C₄H₃NMe-1), are synthesized by metathesis reactions from Me₃SnCl with 1(N)- and 2(C)-lithium pyrroles, respectively. An almost similar procedure gives monomeric dimethylstannylbis(pyrroles), Me₂SnR₂ ( 1 a – 3 a ), from Me₂SnCl₂ and 1-Li-pyrrolides (1 : 2 molar ratio) in good yields. Lithiated 1,2,5-trimethylpyrrole and Me₃SnCl forms the compound Me₃Sn? CH₂? C₄H₂Me(-5)NMe ( 8 ), the reaction of Me₂SnCl₂ with 2-lithium-1-methylpyrrole gives oligomeric [Me₂Sn? C₄H₂NMe? ]_x, ( 6 a ). The mass-, NMR, and vibrational spectra have been measured and discussed. The results of the X-ray structure determinations of Me₃Sn? NC₄H₄ ( 1 ) and Me₂Sn(? NC₄Me₄)₂ ( 3 a ) are compared with the structures of the known dimethylmetal pyrroles of Al, Ga, and In.     

Darstellung,Eigenschaften und Molekülstrukturen von Dimethylaminomethylferrocenyl‐Verbindungen ausgewählter Elemente der Gruppen 13 und 14

Preparation, Properties, and Molecular Structures of Dimethylaminomethyl Ferrocenyl Compounds of selected Elements of Group 13 and 14 Dimethylmetalchlorides of gallium and indium react with dimethylaminomethylferrocenyllithium (FcNLi) to give the corresponding dimethylmetaldimethylaminomethylferrocenes 1 and 2 [Me₂MFcN; M=Ga, In]. In a similar manner dialkylmetaldichlorides of germanium and tin yield the expected chlordialkylmetaldimethylaminomethylferrocenes 3 – 5 [R₂(Cl)MFcN; M=Ge; R = Me ( 3 ), M=Sn; R=Me ( 4 ), Ph ( 5 )]. In a reaction of Me₃Al and Me₂AlCl with dimethylaminomethylferrocene the formation of the 1 : 1 adducts 7 and 8 could be observed. All compounds were characterised by ¹H and ¹³C nmr spectroscopy. The molecular structures of 1 , 3 , 4 and 7 were determined. 3 and 4 build in contrast to 1 monomeric molecules with chelat rings as a result of the M–N coordination. Compound 7 consist of monomeric molecules with 4 coordinated Al atoms.     

Darstellung einer molekularen,monomeren thallium(I)-Verbindung mit einem neuen chelatisierenden Liganden

The chelating ligand Me₃COSiMe₂N(CMe₃)H (III) can easily be prepared in high yields and has been employed for the synthesis of some metal derivatives. With n-butyllithium III forms [Me₂Si(Me₃CO)(Me₃CNLi)]₂ (IV), which is found to be dimeric in solution and in the gas phase. When IV is allowed to react with thallium(I) chloride in diethyl ether the monomeric, highly reactive Me₂Si- (Me₃C$\text{O)(Me}{}_3\text{CNTl}$) (II) is formed under precipitation of lithium chloride. The cyclic structure and the physical properties of II can be understood on the basis of isosteric relation to cyclic diazasilastannylenes. II forms the tetramer (TlOMe)₄ with methanol and does not add methyl iodide to the metal, the thalium containing product being TII. With magnesium dichloride in diethyl ether yields thallium(I) chloride and the spiro compound [Me₂Si(Me₃CO)(Me₃CN)]₂-Mg (VI), in which magnesium exhibits 4-fold coordination.     

Structure characterisation of the organoaluminium intermediate resulting from the alkylation of a chelated carbonyl group. Molecular structure of the trinuclear [MeAl][C12H20O4][AlMe2]2 compound

The interaction of Me₃Al with Me₂Al(acac) results in the carbonyl alkylation of the chelating acetylacetonate ligand and formation of trinuclear complex [MeAl][C₁₂H₂₀O₄][AlMe₂]₂ (1). The title compound has been characterised by ¹H-and ²⁷Al-NMR spectroscopy. The ¹H-NMR spectra are consistent with the presence of two distinct isomers in an equimolar ratio: cis-1 and trans-1. Both isomers contain two methylated acac units bridged by three organoaluminium moieties: central five-coordinated methyl aluminium species and two terminal four-coordinated dimethylaluminium species. The structure of cis-1 has been confirmed by X-ray crystallography which revealed that the five-coordinated aluminium atom rises in almost ideal square pyramidal geometry. The role of the molar ratio of reactants is discussed.     

Versatile Conversion of N‐Heterocyclic Silylene to Silyl Metal Compounds by Insertion of Divalent Silicon into Metal–Carbon and Metal–Hydrogen Bonds

The facile one‐pot reaction of the stable N‐heterocyclic silylene LSi: 1 (L?(ArN)C(?CH₂) CH?C(Me)(NAr), Ar=2,6‐iPr₂C₆H₃) with Me₂Zn, Me₃Al, H₃Al‐NMe₃, and MeLi has been investigated. The silicon(II) atom in 1 is capable of insertion into the corresponding M? C and Al? H bonds under very mild reaction conditions. Thus, Me₂Zn furnishes the bis(silyl) zinc complex LSi(Me)ZnSi(Me)L 2 as the sole product, irrespective of the molar ratio of the starting materials applied. Moreover, the reactions of 1 with Me₃Al, H₃Al‐NMe₃, and MeLi lead directly to the 1,1‐addition products LSi(Me)(Al(thf)Me₂) 3 , LSi(H)(AlH₂(NMe₃)) 4 , and LSi(Me)Li(thf)₃ 5 , respectively. All new compounds 2 – 5 were fully characterized by multinuclear NMR spectroscopy, mass spectrometry, elemental analyses, and single‐crystal X‐ray diffraction analyses.     

Zur präparativen Bildung des Tri-tert.-butyl-nonaphosphans(3); P9(CMe3)3

Formation of Tri-tert.-butyl-nonaphosphane (3); P₉(CMe₃)₃ P₉(CMe₃)₃ 1 is formed by the reaction of “Na₃P/K₃P” with (Me₃C)PCl₂ [maximum yield 20% with regard to (Me₃C)PCl₂]. The molar ratio of the reactants used on this synthesis is Na/K:P₄:(Me₃C)PCl₂ is 4:1:2. The method of preparation is described.     

Die 3-(N,N-Dimethylamino)prop-1-enyl-Gruppe als Chelatligand in Organoindium-Verbindungen

The 3-(N,N-Dimethylamino)prop-1-enyl Group as a Chelate Ligand in Indium Organyls InBr₃ reacts with Me₂NCH₂CH?CHMgCl (molar ratio 1 : 2) to form (Me₂NCH₂CH?CH)₂InBr ( 1 ) as the first indium alkenyl compound with amino-functionalized alkenyl groups. The X-ray structure determination shows the formation of a chelate complex. 1 crystallizes in the orthorhombic space group Fddd with the unit cell parameters a = 14.904(2) Å, b = 17.140(1) Å and c = 21.035(2) Å. By reaction of Me₂InBr with Me₂NCH₂CH?CHMgCl (molar ratio 1 : 1) (Me₂NCH₂CH?CH)InMe₂ ( 2 ) is formed as a colorless, at room temperature liquid, monomeric compound. The n.m.r. and mass spectra are discussed.     

Herstellung und Anionenkonstitution von kristallinen Tetramethylammonium-alumosilicaten und -alumosilicatlösungen

Synthesis and Anion Constitution of Crystalline Tetramethylammonium-aluminosilicates and -aluminosilicate Solutions Crystalline tetramethylammonium aluminosilicates with molar constitutions of wN(CH₃)₄OH · xSiO₂ · y Al₂O₃ · zH₂O and w = 1 to 1.2; x = 1; y = 0.02 to 0.5; z = 8.1 to 9.7 has been obtained from mixtures of diluted TMA aluminate and TMA silicate solutions with different molar Si/Al ratios by concentration and cooling down of the mixtures. Investigations of the TMA aluminosilicates by means of trimethylsilylation method show that the structure of the TMA aluminosilicates consists of double fouring units in analogy to the aluminum free TMA silicates. The arrangement of the Al atoms in the double four-rings agrees in general with Loewenstein's rule and leads to five distinct types of double four-rings with different Al content and Si? Al distribution. By the methods used in this study no distinction can be made between monomeric or polymeric arrangements of the double four-ring units. The existence of aluminosilicate anions in aqueous solutions is discussed.     

Group 1 and 13 complexes of aryl-substituted bis(phosphinimino)methyls

The organolithium reagent [{HC(Ph₂PNC₆H₂Me₃-2,4,6)₂}Li(OEt₂)] was easily obtained by deprotonation of H₂C(Ph₂PNC₆H₂Me₃-2,4,6)₂ with nBuLi in diethyl ether solution. The crystal structure of [{HC(Ph₂PNC₆H₂Me₃-2,4,6)₂}Li(OEt₂)] has been determined and shown to consist a monomeric chelate structure that contains a distorted, trigonal planar lithium centre. The ligand precursor has also been deprotonated with both Me₃Al and Me₂AlCl to yield the tetrahedral organoaluminium complexes, [{HC(Ph₂PNC₆H₂Me₃-2,4,6)₂}AlMe₂] and [{HC(Ph₂PNC₆H₂Me₃-2,4,6)₂}Al(Cl)Me]. Reaction of [{HC(Ph₂PNC₆H₂Me₃-2,4,6)₂}Li(OEt₂)] with either AlX₃ (X=Cl, Br, I) or GaCl₃ yielded a series of dihalo derivatives [{HC(Ph₂PNC₆H₂Me₃-2,4,6)₂}MX₂] all of which have been shown to exist as similar monomeric species containing four-coordinate group 13 centres.     

Experimental standard molar enthalpies of formation of crystalline 3,5-dimethylpyrazole, 3,5-dimethyl-4-nitrosopyrazole, 1,3,5-trimethyl-4-nitrosopyrazole,and 3,5-dimethyl-1-phenyl-4-nitrosopyrazole

The standard (p^o =  0.1 MPa) molar enthalpies of combustion in oxygen, at T =  298.15 K, for crystalline 3,5-dimethylpyrazole (Me₂Pyr), 3,5-dimethyl-4-nitrosopyrazole (Me₂PyrNO), 1,3,5-trimethyl-4-nitrosopyrazole (Me₃PyrNO), and 3,5-dimethyl-1-phenyl-4-nitrosopyrazole (Me₂PhPyrNO) were measured by static-bomb calorimetry. These values were used to derive the standard molar enthalpies of formation of the crystalline compounds. The standard molar enthalpies of sublimation for these four compounds were measured by microcalorimetry.The experimental results obtained allow us to derive the values of the standard molar enthalpies of formation, in the gaseous state, for the monomeric compounds involved in this work. These last values are discussed comparatively with results previously obtained for some aromatic nitroso derivatives.     

Dimethylmetall-tropolonate des galliums,indiums und zinns

The reaction of GaMe₃ and InMe₃ (Me = CH₃) with equimolar amounts of α-tropolone forms dimethylgallium tropolonate and dimethylindium tropolonate, respectively, in high yields. Both compounds are monomeric in solution, almost planar 7-/5-ring bicyclic structures of C_2v symmetry can be discussed. According to the X-ray structure determination of Me₂GaTrop (Trop = C₇H₅O₂) this compound is dimeric in the solid state and crystallizes in the monoclinic space group P2₁/c with 4 formula units (2 dimers) per unit cell. Me₂SnTrop₂ is formed by the interaction of Me₂SnCl₂ with LiTrop in a $\text{1}\text{2}$ molar ratio. This ditropolonate is monomeric not only in solution but also in the solid state. The compound crystallizes in the triclinic space group P$\text{1}$ (Z = 4), and the molecules have a cis-structure of approximate C₂-symmetry. The vibrational and NMR spectra of all compounds were measured and are partly assigned.     

Ionische Strukturen von 4- bzw. 5fach koordiniertem Silicium Neue ionische Festkörperstrukturen von 4- bzw. 5fach koordiniertem Silicium: [Me3Si(NMI)]+Cl−, [Me2HSi(NMI)2]+Cl−, [Me2Si(NMI)3]2+ 2 Cl−· NMI

Ionic Structures of 4- and 5-coordinated Silicon. Novel Ionic Crystal Structures of 4- and 5-coordinated Silicon: [Me₃Si(NMI)]⁺ Cl^?, [Me₂HSi(NMI)₂]⁺ Cl^?, [Me₂Si(NMI)₃]²⁺ 2 Cl^?. NMI Me₃SiCl forms with N-Methylimidazole (NMI) a crystalline 1:1-compound which is stable at room temperature. The X-ray single crystal investigation proves the ionic structure [Me₃Si(NMI)]⁺Cl^? 1 which is the result of the cleavage of the Si? Cl bond and the addition of an NMI-ring. The reaction of Me₂HSiCl with NMI (in the molar ratio of 1:2), under cleavage of the Si? Cl bond and co-ordination of two NMI rings, yields the compound [Me₂HSi(NMI)₂]⁺Cl^? 2 . The analogous reaction of Me₂SiCl₂ with NMI (molar ratio 2:1) leads to a compound which consists of Me₂SiCl₂ and NMI in the molar ratio of 1:2. During the sublimation single crystals of the compound [Me₂Si(NMI)₃]²⁺ 2 Cl^?. NMI 3 are formed.     

C-NMR study of Ti(IV) species formed by Cp*TiMe3 and Cp*TiCl3 activation with methylaluminoxane (MAO)

Using ¹³C- and ¹H-NMR spectroscopy, titanium(IV) species formed in the catalytic systems Cp*TiMe₃/MAO and Cp*TiCl₃/MAO (Cp*=C₅(CH₃)₅) in toluene and chlorobenzene were studied within the temperature range 253-293 K and at Al/Ti ratios 30-300. It was shown that upon activation of Cp*TiMe₃ with methylaluminoxane (MAO) mainly the ‘cation-like’ intermediate Cp*Me₂Ti⁺←Me⁻Al(MAO) (2) is formed. Three types of titanium(IV) complexes were identified in Cp*TiCl₃/MAO catalytic system. They are methylated complexes Cp*TiMeCl₂ and Cp*TiMe₂Cl, and the ‘cation-like’ intermediate 2. Complex 2 dominates in Cp*TiCl₃/MAO system in conditions approaching to those of practical polymerization (Al/Ti ratios more than 200). According to the EPR measurements, the portion of EPR active Ti(III) species in the Cp*TiCl₃/MAO system is smaller than 1% at Al/Ti=35, and is about 10% at Al/Ti=700.     

Reaktionen von TaCl5, MoCl5 und WCl6 mit Bis(trimethylsilyl) carbodiimid

Reactions of TaCl₅, MoCl₅, and WCl₆ with Bis(trimethylsilyl)carbodiimide When TaCl₅ reacts with Me₃SiNCNSiMe₃ (Me = CH₃) in a 1:1 molar ratio, 1 mol Me₃SiCl and dimeric [Cl₄TaNCNSiMe₃]₂ is formed. The vibrational spectra (IR and Raman) show a planar structure of approximate C_2h symmetry. Polymeric [Cl₄WNCN]_n is formed by the reaction of WCl₆ and Me₃SiNCNSiMe₃, but 2 mol Me₃SiCl result in this 1:1 molar interaction. On the other hand MoCl₅ and Bis(trimethylsilyl)carbodiimide (molar ratio 2:1) forms polymeric [(Cl₄Mo)₂NCN]_n, a compound with Mo? N? Mo and Mo—(Cl₂)—Mo bridges. The IR spectra of these carbodiimide derivatives are used for structural suggestions.     

Microwave-assisted reconstruction of Ni,Al hydrotalcite-like compounds

The microwave-assisted reconstruction of Ni,Al hydrotalcite-like compounds (HTlcs) with Ni/Al molar ratios 2/1 and 3/1 has been studied. Mixed oxides obtained after calcination of the HTlcs are immersed in three different solutions containing carbonate, distilled water and an aqueous NH₃ solution, and then heated at different temperatures for increasing periods of time under microwave radiation. The evolution of the structure during the treatment is followed by powder X-ray diffraction, FT-IR and vis-UV spectroscopies and SEM and TEM microscopies. Full recovery of the original layered structure is achieved in short periods of time for the 2/1 samples when the calcined HTlcs are rehydrated in the Na₂CO₃ solution, but more drastic conditions are necessary for the 3/1 samples and the reconstruction seems not to be complete. Finally, only a partial reconstruction is observed in distilled water or NH₃ aqueous solution.     

The conversion of alkynes into substituted cyclopropanes effected by CH2I2-R3Al (R = Me, Et, i-Bu)

The reaction of mono- and disubstituted alkynes with CH₂I₂-R₃Al (R = Me, Et, i-Bu) was studied. It was found that the reaction of alkynes with CH₂I₂ in the presence of Me₃Al gives β-iodoethyl-substituted cyclopropanes. The use of Et₃Al or i-Bu₃Al affords exclusively cyclopropylic organoaluminum compounds.     

Synthese und Kristallstruktur des trimeren [(Me3Si)2CH]2Al?CN

Synthesis and Crystal Structure of the Trimeric [(Me₃Si)₂CH]₂Al? CN Tetrakis[bis(trimethylsilyl)methyl]dialane(4) 1 with an Al? Al bond reacts with tert-butyl isocyanide in the molar ratio of 1:2 within three days to give a mixture of several unknown products, from which the title compound 4 is isolated in a 26% yield by recrystallization from n-pentane. 4 is a trimer in the solid state via Al? C?N? Al bridges showing a nine-membered Al₃C₃N₃ heterocycle in a boat conformation. In contrary to the reaction with phenyl isocyanide the expected dark red product of the twofold insertion into the Al? Al bond under formation of a carbon-carbon single bond is detected only spectroscopically as a minor by-product.     

Thermodynamic functions and structure of gallium + tellurium liquid alloys

In the frame of our systematic investigation on strongly interacting alloy systems, we have measured the molar enthalpy of formation, ΔH_f, of liquid Ga + Te alloy at 1200 and 1238 K by direct reaction calorimetry, using a Calvet microcalorimeter. The enthalpy of formation, with reference to the pure liquid components, is negative over the whole range of mole fractions x and has a minimum at x_Te ≈ 0.6. ΔH_f(l, x_Te = 0.61, 1200 K) = ?(38.8 ± 0.8) kJ mol^?1. This is evidence for strong chemical interactions in the liquid phase with formation of Ga₂Te₃ clusters. No significant difference was noted between the enthalpies at 1200 and 1238 K. Comparison of the molar integral enthalpies and entropies of formation of liquid Me_0.4^IIITe_0.6 alloys (Me^III  Al, Ga, In, and Tl) shows that the stability of the Me₂Te₃ clusters decreases in the series Al > Ga > In > Tl.