S. Pasynkiewicz

The synthesis of titanium(II)_complexes containing methylbenzene ligands

Abstract A new method for the preparation of titanium(II) complexes of the type Ar·TiCl 2 ·Al 2 Cl 6 (where Ar is tetra-, penta- or hexa-methylbenzene) is described. The present work supports the π nature of the bond between the titanium atom and the aromatic ligand as postulated elsewhere.

The reaction of organoaluminium compounds with ketones

Abstract Reactions of ethylaluminium compounds with diethyl ketone and diisopropyl ketone were investigated. It was found that triethylaluminium reacts with diethyl ketone to give products of addition, reduction and enolization reactions. The yield of addition reaction product increases and the yield of reduction reaction product decreases when larger ratios of triethylaluminium to ketone are used, or when the temperature is lowered Triethylaluminium and diethylaluminium chloride react with diisopropyl ketone to give reduction reaction products only. Ethylaluminium dichloride does not react with diisopropyl ketone up to 100°. The reaction mechanism is discussed.

Proton magnetic resonance studies on the structure of tetraethylalumoxane

Abstract The structure of tetraethylalumoxane was studied. Comparison of low temperature PMR spectra of (Et 2 Al) 2 O and Et 3 Al suggested that the ethyl groups bridge the aluminium atoms in alumoxane. The investigation of alkyl group exchange between tetraethylalumoxane and tetramethyllead confirm the postulated structure.

Reaction of triethylaluminium with esters

Abstract Reactions of triethylaluminium with certain esters with investigated. The reactions were found to afford products of addition and reduction. The effects of the carbonyl carbon electrophilicity on the reaction yhield was investigated. The reaction mechanism is discussed.

Phenoxyaluminium compounds IV. syntheses and structures of monomeric (2,6-DI-t-Butyl-4-methylphenoxy)aluminium compounds

Abstract The preparations of monomeric dialkyl(2,6-di-t-butyl-4-methylphenoxy)aluminium (alkyl  methyl, i-butyl) and i-butylbis(2,6-di-t-butyl-4-methyl-phenoxy)aluminium are described and their reactions, PMR and ESR spectra are reported.

Synthesis and properties of monophenoxyalumunium compounds

Abstract Dimethylphenoxyaluminium, methylphenoxychloroaluminium and phenoxydichloroaluminium have been prepared. Their molecular weights have been determined and their IR spectra analysed. The NMR spectrum of methylphenoxychloroaluminium has been investigated. At room temperature in a hydrocarbon solution the trimer is the stable associated form, but at higher temperatures the formation of the dimer is increasingly favoured. The occurrence of mixed oxygen-chloride bridges in fairly stable transitional forms of trimeric methylphenoxychloroaluminium and phenoxydichloroaluminium is proposed.

Reactions of trialkylaluminium with sterically hindered diols

Abstract The reactions of trialkylaluminium R3Al (R=Me, Et) with 2,4-pentanediols [(CH3)2(OH)CCH2C(CH3)2OH (A)], [(CH3)2(OH)CCH2CH(OH)CH3 (Ḇ)] and 2,5-dimethyl-2,5-hexanediol (C) were studied. Sterically hindered 2,4-pentanediols (A, Ḇ) react with alkylaluminium compounds to form mainly cyclic compounds 1–3 of a formula R5Al3[diol(−2H)]2 possessing one central five-coordinated aluminium atom and two terminal four-coordinated aluminium atoms. All the compounds were characterised by means of NMR spectra, elemental analysis and molecular weight determination. The molecular structure of the solid Me5Al3[O(CH3)2CCH2C(CH3)2O]2 1 was determined by X-ray diffraction analysis. Substituted at terminal carbon atoms 2,5-dimethyl-2,5-hexanediol (C) forms organoaluminium oligomers exclusively. The influence of the diol carbonchain lengths and its substituents on the yield of the cyclic complexes and organoaluminium oligomers are discussed.

Reactions of trimethylaluminium with aliphatic diols

The reactions of trimethylaluminium with aliphatic diols, derivatives of 1,4-butandiol and 1,3-propadiol were studied. A mixtures of linear and cyclic organoaluminium compounds were the products of these reactions carried out for AIME3: diol molar ratios of 3:2 or greater. One of the products isolated in all the studied reactions was a complex of a formula Me5Al3[diol(-2H)]2 possessing one central five-coordinated aluminium atom and two terminal four-coordinated aluminium atoms. All the complexes were characterized by means of 1H, 13C and 27Al NMR spectra, elemental analysis and molecular weight determination.

Phenoxyaluminium compounds : VII. Reactions of organoaluminium compounds with hindered phenols

Reactions of Me3Al, i-Bu3Al, Me2AlCl and Me2AlCCMe with 2,6-di-t-butyl-4-methylphenol have been studied at different molar ratios of the reactants. It is found that in the reaction with the phenol, trimethylaluminium forms monomeric methylaluminium diphenoxide; triisobutylaluminium gives both monomeric mono- and di-phenoxyaluminium (depending on molar ratios of the reactants) and dimethylchloroaluminium forms dimeric methylphenoxyaluminium chloride. It is found that methylpropynylaluminium phenoxide is unstable and disproportionates in hydrocarbon solutions. The mechanisms of some of these reactions are suggested.

Reactions of nickelocene with methyl-, ethyl- and vinyl-lithium compounds. Hydrogen elimination and cyclopentadienyl ring hydrogenation

Abstract It has been shown that bis(cyclopentadienyl)(μ-cyclopentadiene)dinickel, (NiCP)2(η-C5H6), and (η5-cyclopentadienyl) (η3-cyclopentenyl)nickel, CpNi(η3-C5H7), are formed in the reaction of nickelocene with methyl-lithium and with 1-phenyl-2-methyl-propenyl-lithium. The compound (NiCp)2(μ-C5H6) can be only formed as a result of the reduction of the cyclopentadienyl ring bonded to the nickel atom whereas the formation of CpNi(η3-C5H7) can be explained by the further hydrogeneration of cyclopentadiene formed in the earlier reaction steps. (NiCp)2(μ-C5H6) has been fully characterised spectrometrically and its X-ray structure determined. It crystallises in the orthorhombic system, space group Pnma, with four molecules per unit cell.