The syntheses of a number of new [3.3.1]bicyclononane derivatives are described. Representative compounds include 1-cyano-3-methyl-4-hydroxybicyclo[3.3.1]nonan-9-one, 1-amino-3-methyl-4,9-dihydroxybicyclo[3.3.1]nonane, ethyl-7-methylbicyclo[3.3.1]non-3-en-9-one-1-carboxylate, as well as the following derivatives of ethyl-bicyclo[3.3.1]non-3-en-9-one-1-carboxylate: 1-aminobicyclo[3.3.1]non-3-en-9-one, ethyl-3-hydroxy-4-bromobicyclo[3.3.1]nonan-1-carboxylate, ethyl-4-bromobicyclo[3.3.1]nonan-3,9-dione-1-carboxylate and ethyl-bicyclo[3.3.1]nonan-3,9-dione-1-carboxylate. A Michael condensation of 2-cyanocyclohexanone with alpha-methyl acrolein afforded 1-cyano-3-methyl-4-hydroxybicyclo[3.3.1]nonan-9-one as a 1:1 complex. Acetylation furnished a mixture of the epimeric acetates, which were separated by fractional crystallization. Oxidation of 1-cyano-3-methyl-4-hydroxybicyclo[3.3.1]nonan-9-one converted it into 1-cyano-3-methylbicyclo[3.3.1]nonan-4,9-dione. Reduction of 1-cyano-3-methyl-4-hydroxybicyclo[3.3.1]nonan-9-one, then saponification of the nitrile group, followed by a Hofmann rearrangement of the amide gave 1-amino-3-methyl-4,9-dihydroxybicyclo[3.3.1]nonane. Several attempts were made to effect cyclization between alpha-methyl acrolein and 2-carbomethoxy-4-ethylenedioxycyclohexanone. However, the desired bicyclononane compound was not obtained. An alternative approach was also studied; alkylation using 1-chloro-2-methyl-3-bromopropane and 2-carboethoxycyclohexanone or 2-carbomethoxy-4-ethylenedioxy-cyclohexanone gave in both cases the C-alkylated product. Attempts to cyclize these compounds using a variety of methods gave predominantly 0-alkylated products. The base-catalyzed reaction between 2-carboethoxy-4-methylcyclohexanone and acrolein yielded beta-(1-ethoxycarbonyl-2-keto-5-methylcyclohexyl) propionaldehyde. Treatment of the latter with acid effected cyclization yielding ethyl-7-methylbicyclo[3.3.1]non-3-en-9-one-1-carboxylate. Ethyl-bicyclo[3.3.1]non-3-en-9-one-1-carboxylate was converted by the following steps: saponification of the ester, conversion of the acid into the acid azide, followed by rearrangement of the latter to the amine hydrochloride; addition of base liberated 1-aminobicyclo[3.3.1]non-3-en-9-one. Treatment of ethyl-bicyclo[3.3.1]non-3-en-9-one-1-carboxylate with N-bromosuccinimide in acid solution gave ethyl-3-hydroxy-4-bromobicyclo[3.3.1]nonan-1-carboxylate, which on oxidation furnished ethyl-4-bromobicyclo[3.3.1]nonan-3,9-dione-1-carboxylate. Reductive removal of the bromine with zinc-acetic acid gave ethyl-bicyclo[3.3.1]nonan-3,9-dione-1-carboxylate. Hydrolysis of the ester in the last compound gave the corresponding acid. Attempts to prepare 1-aminobicyclo[3.3.1]nonan-3,9-dione failed. Infrared and n.m.r. spectra were used extensively in the structure determination of these compounds as well as their by-products. The identity of all key-compounds was further corroborated by analytical data and ultraviolet spectra.

The treatment of paramagnetism using the approach of the crystal field theory is discussed, with special emphasis on the tetragonally distorted octahedral field. For the limiting cases when Delta >> lambda for positive and negative Delta, expressions for the susceptibility are derived. Complexes of NbX4 and TaX4 (X= Cl,Br) with pyridine, bipyridyl and tetramethylethylenediamine were prepared and their magnetic susceptibilities studied over a temperature range 90--300°K. The data for all twelve complexes indicate that the Curie-Weiss law is not obeyed: Their effective moments exhibit small temperature dependence and the values at room temperature are well below the spin-only value for a single unpaired electron. Empirical fittings of mueff against kT/|lambda| curves from Figgis (34) show that (a) the sign of a Delta is reversed from that deduced on the basis of the crystal field model, (b) the axial field splittings are greater for the chlorides, and (c) Delta decreases in the order pyridine > bipyridyl > 4meen, for a given halide. The reversal in the sign of Delta is attibuted to the pi-donating effect from the halogens. (b) is accounted for by the order of the halide ions in the spectrochemical series. The lower Delta values for 4meen complexes are explained by the higher basicity of the ligand compared to pyridine and bipyridyl. Pyridine complexes have larger Delta values than the corresponding bipyridyl complexes probably because of the slightly better pi-accepting capacity of pyridine.

Interphase structure studies in the electrochemical adsorption of neutral organic substances at the mercury electrode have been carried out by electrocapillary measurements. New techniques have been developed which increase the accuracy and greatly facilitate the required measurements. Use has been made of a Langmuir type of adsorption equation to evaluate the standard free energy of adsorption of pyridine from an aqueous 0.03M NaClO 4 solution over a range of temperatures. This study enabled the entropies and heats of the electrochemical adsorption to be investigated as functions of electrode charge density and coverage. The adsorption behaviour of acetophenone and its pinacol, 2,3-diphenyl-butane-2,3-diol, were examined in order to provide information required in the interpretation of the kinetic reaction orders for the electrochemical reduction of acetophenone at mercury. The pinacol, the main product of the reduction in acid solution, was found to be more adsorbable than the acetophenone, but the kinetic investigations indicated that the presence of pinacol did not affect the rate of reaction. The order of the surface reaction was found to be dependent on the coverage. An important solvent effect was observed in the comparison of the surface pressure-surface coverage relations obtained for several systems (acetophenone, pinacol and naphthalene in methanolic and aqueous methanolic solutions) in which the same supporting electrolyte was used. The adsorption characteristics of the same solute from various solvents were found to be different, but were similar for different solutes adsorbed from the same solvent. This behaviour, in conjunction with other effects reported, led to a critical assessment of the value of considering solute-solute interactions in the description of the observed, "non-ideal" Langmuir-type behaviour. The orientation of dipolar neutral adsorbates as a function of charge and surface concentration (and its correlation with the molecular area of the adsorbed species) has been investigated and previous interpretations have been modified. A comparison between the results for the adsorption of pyridine from aqueous NaClO4 and KCl solutions has been made in terms of the analyses based on the Langmuir and Volmer isotherms. A new method for evaluating the true free energy, entropy and heat of adsorption of neutral molecules at a mercury electrode in the region of low surface concentration where adsorption is considered "ideal", was investigated. In this study, use was made of the Volmer equation of state. The adsorption of D- and L-mandelic acid in the presence of L-lactic acid was investigated in order to evaluate possible stereospecific effects in adsorption. However, the differences which were observed in the corresponding surface pressures can be interpreted in terms of intra- and intermolecular esterification processes in the ad-layer, a situation which renders identification of true stereospecific effects somewhat ambiguous. A review of a number of critical aspects of adsorption phenomena is presented in which the emphasis is placed on structural effects in the adsorbed phase.

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The preparation of two tetravalent d2 chromium alkyls is revisited. Their ability to work both as starting materials for further functionalization and as Ziegler-Natta catalysts is investigated. The clarification of the reaction pathway through which a trivalent chromium salt may form a homoleptic tetravalent derivative is also considered. Finally, the elucidation of the nature of the Cr-Cr interaction in a unique [R2Cr] 4 tetranuclear cluster and evaluation of its stability is undertaken. This is followed by a reassessment of the stability of tetravalent vanadium alkyls. Wilkinson first reported, in the seventies, the preparation of homoleptic R4V species [R = C6H5, CH2Si(CH 3)3]. The full characterisation of a homoleptic R4V, by crystal structure, and testing the catalytic activity is reported. The alpha,alpha-diiminopyridine ligand {alpha,alpha' -[2,6-(i-Pr)2PhN=C(Me)]2(C 5H3N)} has recently attracted considerable attention because of its ability to form highly active polymerization catalysts. Recent work from this research group and others has shown that this alpha,alpha '-diiminopyridine ligand can be involved in the organometallic transformations of the metal center. The ability of the ligand to accept or to donate negative charge to the metal is central to the fine tuning of the redox potential of the metal, and of its Lewis acidity that in turn determines the catalytic behaviour. A clarification for the ability of this remarkable ligand system to accept negative charge is offered. Reductions of {alpha,alpha'-[2,6-(i-Pr) 2PhN=C(Me)]2(C5H3N)} with strong reductants such as Li and Li(naftalenide) and in the absence of transition metals were carried out to yield rare case trilithium organyls.

Synthesis of several interrelated metallo-compounds is described. They are of intrinsic interest in their own right and were designed as intermediates and model studies for construction of various acetylene metal systems with interesting synthetic and optical potential. Synthesis of a triacetal and its eta6-tricarbonylchromium(0) complex 31 is described. Further transformations towards an eneyne derivative of 31 were complicated by the inherent instability of the complex towards oxidative decomplexation. Synthesis of a series of hexa-substituted eta 6-tricarbonylchromium(0) complexes 39--47 (E = H, Me, SiMe3, SnMe3, Cl, Br, I, COH, CO2Me) and 54--57 (E = H, Cl, Br, I) by di- or tri-lithiation of the parent compounds followed by quenching with a series of electrophiles is reported. Attempts to obtain alkynylated derivatives of the complexes by Sonagashira coupling reactions failed to produce the desired products. A novel tridurylborane 83, incorporating three azulenyl substituents, was prepared and displayed unique photophysical properties with an absorption maximum nearly 80 nm longer than that of its precursor. A new class of heteroatom-containing triarylboranes 79 (R = OMe) and 96 (R = Me) were synthesized. Triarylborane 96 displayed broadened resonances in the 1H NMR spectrum at room temperature and a low-temperature 1H NMR study revealed that the borane existed as an approximate 10:1 ratio of two enantiomeric sets of conformational isomers. Triarylborane 96 was further extended by sequential Sonagashira coupling reactions to yield the highly fluorescent chromophore 110, which exhibited intense and long-wave absorption and emission maxima.

The gas-solid reaction of tetra(neopentyl)zirconium with the surface of Aerosil 200 pretreated thermally at 200°C has been investigated. Consistent with previous investigations of a similar reaction involving deposition of tetra(neopentyl)zirconium from solution, a unique supported organometallic fragment is formed. It was characterized by IR, 13C CP/MAS NMR, XAS and analytical techniques as (≡SiO)2Zr(CH2 C(CH3)3)2. Thermolysis of silica-supported bis(neopentyl)zirconium(IV) at ca. 120°C results in the extrusion of one equiv. of neopentane. The nature of the remaining surface organometallic fragment was inferred, by its reactivity in olefin metathesis as well as by curve-fitting of its EXAFS spectrum, to be neopentylidenezirconium(IV), presumably formed by alpha-H abstraction. This result is analogous to previously established transformations of bis(alkyl) complexes of titanium, vanadium and chromium supported on silica, but was unexpected since earlier reports of the thermolysis of Zr(CH2C(CH3)3) 4 supported gamma-H abstraction and the formation of a zirconacyclobutane intermediate. The alpha-H abstraction occurs with pseudo-first-order kinetics and activation parameters DeltaH‡ = 24(5) kJ/mol and DeltaS ‡ = -19(7) J/K•mol. Both the bis(neopentyl)- and neopentylidenezirconium(IV) fragments were found to catalyze polymerization of ethylene, at room temperature without any added cocatalyst. The reactions are pseudo-first-order in P(C2 H4).