Faculty of Science School of Chemistry 9309501t Stanley.manzini@up.ac.za / The solventless reaction between Mn(CO)4(PPh3)Br and PPh3 as neat reagents using FTIRS was conducted and the activation enthalpy change of formation was found to be 143 ± 19 kJmol-1 while the activation entropy change of formation was 104 ± 7 Jmol-1K-1. The same reaction was also carried out in chloroform and the activation enthalpy change of formation was found to be 146 ± 8 kJmol-1 while the activation entropy change of formation was 114 ± 6 Jmol-1K-1. When the reaction was conducted in TCE solution, the activation enthalpy and entropy changes of formation were 137 ± 6 kJmol-1 and 97 ± 5 Jmol-1K-1 respectively. The solventless reaction of Mn(CO)4(PPh3)Br with PPh3 in KBr matrix using DRIFTS was also conducted and the activation enthalpy change of formation was found to be 169 ± 28 kJ.mol-1 while the activation entropy change of formation was 204 ± 57 J.mol-1.K-1. The sample preparation method, the type of support and the particle size of the support material influenced the reaction rate. The soventless reaction Mn(CO)4LBr + L → Mn(CO)3L2Br + CO [L= P(p-C6H4-R)3, R = Ph, MeO, Cl, F] in KBr using DRIFTS was also studied. It was found that the electronic effects of the ligand already attached on the metal complex influenced the rate of the reaction. An optical microscopy study of the reaction Mn(CO)4LBr + L' → Mn(CO)3LL'Br + CO [L= P(p-C6H4-R)3, R = H, Ph, MeO] was undertaken in an attempt to reconcile the wellbehaved reaction kinetics of the solventless reactions with solventless reactions by observing the microscopic behaviour of the reagents. The reactions were observed to go through a melt phase at temperatures much lower than the lowest melting point of the reagents, provided the reagents were in contact with each other. Isolated reagents neither reacted nor melted. The molten reagent thus served as a medium that allowed the diffusion of the reagents and products to ensure well-behaved kinetics. Investigation using 31P NMR demonstrated that the dissociation of the attached phosphine ligands also iii iv took place. The evidence obtained using the various techniques enabled the elucidation of the reaction mechanism. The solventless reaction, (η5-C5H5)2ZrCl2 + Na+RCOO-, R = C6H5, p-C6H4-NO2, p-C6H4- NH2 → (η5-C5H5)2ZrCl(RCOO) + NaCl did not occur but the reaction was found to take place in the NMR solvent. Single crystal XRD study of (η5-C5H5)2ZrCl(RCOO) R = C6H5, p-C6H4-NO2 revealed that the carboxylato ligand was coordinated in a bidentate fashion. The reaction of chlorobis(η5-cyclopentadienyl)hexylzirconium(IV) with internal hexene isomers failed to yield terminal olefins even under harsh experimental conditions. Isomerisation reactions using substituted zirconium metallocenes also failed to produce the terminal olefin. The reaction of Cp2ZrCl2 / n-BuLi with internal hexenes yielded a stoichiometric amount of 1-hexene. The reaction was found to be catalytic in Cp2ZrCl2 but limited by the amount of n-BuLi.

ABSTRACT Solventless reactions of substituted cyclopentadienyl metal carbonyls of iron and ruthenium with electron donor ligands have been carried out. The reactions between CpFe(CO)2I and a range of phosphine ligands occurred in melt phase and yielded two typical compounds : salt product, [CpFe(CO)2PR3]I, and non-salt product, CpFe(CO)PR3I with the salt product being predominant. The complex [CpFe(CO)2]2 was used to catalyze these reactions. The progress of the reactions was followed by 1H NMR spectroscopy. The characterization of products correlates well with the products obtained when working in solution medium. The presence of a Me substituent on the Cp ring was found to favour the salt product formation but generally led to lower rates of reaction. Solventless reactions between RCpRu(CO)2I (R = H, Me) and solid phosphine ligands were also carried out. It has been observed that the ruthenium complexes were less reactive compared with their iron analogues but led to the same types of products namely salt and non-salt. The phosphite ligands were found to be less reactive than their phosphine analogues. In fact, the solventless reactions between RCpM(CO)2I (R = H, Me; M = Fe, Ru) were very slow even in the presence of [CpFe(CO)2]2 as a catalyst. However, when Me3NO.2H2O was added to the reaction mixture in solventless conditions, the non-salt product was obtained in a short period of time at 80oC. A range of cyclopentadienyl based metal complexes e.g [CpMo(CO)3]2, [MeCpRu(CO)2]2 etc. and palladium based compounds such as PdO, Pd/CaCO3 5% etc. were found to be good catalysts for the solventless reactions between CpFe(CO)2I and PPh3. Solventless migratory-insertion reactions have been successfully conducted between CpFe(CO)2CH3 and a range of solid phosphine ligands. Only the acetyl products, CpFe(CO)[PR3]COCH3 were obtained. SO2 insertion into RCpFe(CO)2R’ (R = H, CH3; R’ = CH3, CH2Ph) occurred quite easily at room temperature. However, when R was a carboxylic acid group, CO2H, no reaction took place. CO insertion into the same systems did not happen in solventless conditions.

Yes / A continuous, scalable, and solvent‐free method for the synthesis of various naphthalic imides and perylene diimides (PDIs) using twin‐screw extrusion (TSE) is reported. Using TSE, naphthalic imides were obtained quantitatively without the need for excess amine reactant or product purification. With good functional‐group tolerance, alkyl and benzyl amine derived PDIs (incl. commercial dyes) were obtained in 50–99 % yield. Use of K2CO3, enabled synthesis of more difficult aniline‐derived PDIs. Furthermore, an automated continuous TSE process for Pigments Black 31 and 32 is demonstrated, with a throughput rate of about 1500 g day−1, corresponding to a space time yield of about 30×103 kg m−3 day−1, which is 1–2 orders of magnitude greater than for solvent‐based batch methods. These methods provide substantial waste reductions and improved efficiency compared to conventional solvent‐based methods. / Engineering and Physical Sciences Research Council. Grant Numbers: EP/L019655/1, IAA1718-04-1117

Student Number : 0009404H - PhD thesis - School of Chemistry - Faculty of Science / Six-coordinate ruthenium complexes of the type ttt-RuX2(RNC)2(PPh3)2 (X = Cl ; R = tBu, 2,6-xylyl, benzyl, 2-OMe-4-Clphenyl and iPr; X = Br; R = = tBu, 2,6-xylyl, benzyl, iPr ) were synthesized and fully characterised by IR, NMR spectroscopy and elemental analysis. These complexes were all found to undergo solid-state isomerisation from the ttt-isomer to the cct-isomer. It was found that solid state isomerisation occurred before melting i.e. in the solid state for all the ttt-RuX2(RNC)2(PPh3)2 complexes investigated . The thermal solid state isomerisation process was monitored by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), thermomicroscopy and X-ray powder diffraction techniques. The results revealed that the isomerisation process occurred exothermally with darkening of the crystal. A mechanism which involved rotation of small ligands was proposed to explain the solid-state isomerisation process. Kinetic studies of the solid-state isomerisation of some of the ttt-RuCl2(RNC)2(PPh3)2 complexes were carried out and monitored by NMR spectroscopy and compared with kinetic studies performed by XRD methods. The results are similar and also suggest that the isomerisation reaction follows first order kinetics. The crystal and molecular structure of ttt-RuCl2(2,6-xylylNC)2(PPh3)2 was determined by X-ray single crystal diffraction techniques and its structure was compared with related ttt- RuX2(RNC)2(PPh3)2 complexes. Inter-molecular and intra-molecular interactions in these molecules in the solid state were analysed and used to rationalise the solid-state isomerisation results. The results obtained for the ruthenium complexes suggested that other six-coordinate complexes could undergo solid state isomerisation reactions and this study was extended to molybdenum complexes of the type cis-Mo(CO)4L2. These complexes undergo cis to trans isomerisation in solution. The solid state reactivity of these complexes was investigated for the first time. The complexes with L = PPh2Me and PPh2Et isomerised in the melt whist complexes with L = PPh3 amd P(m-tolyl)3 were indeed found to undergo solid state isomerisation reactions. Structural studies and thermomicroscopic investigations were done on cis- Mo(CO)4(PPh3)2 and Mo(CO)4{P(m-tolyl)3)2 and the results were used to rationalize the solid state reactivity of these complexes.

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<p dir="ltr">Additive manufacturing (AM) of gun propellants is an emerging and promising field which addresses the limitations of conventional manufacturing techniques. Overall, this thesis is a body of work which serves to bridge the gap between fundamental research and application of additively manufactured gun propellants.</p>