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Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1905
Author(s):  
Hary Demey ◽  
Elvira Rodriguez-Alonso ◽  
Elie Lacombe ◽  
Maguelone Grateau ◽  
Nicolas Jaricot ◽  
...  

Torrefaction of almond shells and olive stones, which are typically considered agricultural waste in the southern regions of the European Union, was investigated in this work for application as reducing agents in the metallurgical industry. Four different temperatures were tested: 250, 280, 300 and 350 °C. The evolution of the solid yields with the temperature was determined with TGA measurements. This showed that the duration of torrefaction should not exceed 45 min. The kinetic profiles were successfully fitted using the pseudo-first-order rate equation (PFORE). Then, torrefaction for 45 min was systematically carried out at every temperature and for each resource in a laboratory-scale batch device. The raw and torrefied biomasses were characterized using proximate, ultimate and calorific analyses. The carbon/oxygen ratio and the heating values were increased as a result of the torrefaction severity (from 20 MJ/kg for both raw biomasses to 30 MJ/kg at 350 °C). The highest mass losses were obtained at the highest temperature (67.35 and 65.04 %w for almond shells and olive stones, respectively, at 350 °C). The fixed carbon value also increased, being higher than 67 %w for torrefaction at 350 °C. The large-scale torrefaction at 350 °C (45 min) of these biomasses was carried out in a continuous pilot plant. The solids were characterized as well, and their properties were close to those of the biomasses torrefied in the laboratory-scale batch reactor under the same conditions. This thermal treatment provided biochars with all the required properties to be used as reducing materials in metallurgy.


2021 ◽  
Author(s):  
◽  
Ryan Schwamm

<p>The work presented in this thesis describes the synthesis and stabilisation of heavy p-block elements (defined herein as being those with 5s/p and 6s/p valence electrons) in low oxidation states using sterically demanding ligands based on a di(amido)siloxane framework ([(O{SiMe2N(R)}2]2-, abbrev. [(NONR)]2-).  Chapter 1 gives a general introduction to the heavy p-block elements and discusses a number of concepts that define the molecular chemistry of these elements. A brief introduction into low oxidation state main group chemistry is provided and the importance of sterically demanding ligands in this field of research is introduced. The di(amido)siloxane ligand framework utilised in this work is introduced, with common coordination modes and characteristic properties discussed.  Chapter 2 discusses the chemistry of low oxidation state bismuth complexes and follows a recent report by our group on the first structurally authenticated bismuth(II) radical •Bi(NONAr). The synthesis of a series of bismuth(III) monochloride species Bi(NONR)Cl (R = tBu, Ph, 2,6-Me2C6H3 (Ar’), 2,6-iPr2C6H3 (Ar) and 2,6-(CHPh2)2-4-tBu-C6H2 (Ar‡)) is discussed, and the steric properties of the ligand systems evaluated. In the case of the R = tBu and Ar‡ derivatives, reduction of the bismuth(III) monochloride gave the dibismuthane [Bi(NONtBu)]2 and bismuth(II) radical •Bi(NONAr‡), respectively. Further reduction of the bismuth centres resulted in the formation of rare and unprecedented multimetallic bismuth compounds containing [Bin]n+ cores. These include the Bi4 cluster compound Bi4(NONAr)2, in which the bismuth atoms exist in an unprecedented mixed valent arrangement and may be assigned oxidation states of 0, +1 or +2, and the tribismuthane cluster [Bi3(NONtBu)2]-, which features the first structurally characterised Bi3 chain. The utility of the di(amido) ligand plays a key role in the formation of many of these compounds, with Bi-N bond cleavage suggested to be a key step in many of the reaction pathways.  Chapter 3 discusses the reactivity of the bismuth(II) complexes [Bi(NONtBu)]2, •Bi(NONAr) and •Bi(NONAr‡) which feature either a Bi-Bi bond or a bismuth-centred radical. Initial experiments parallel reported reactivity with halogen radical sources (N-bromosuccinimide or iodine), chalcogens (S, Se, Te) and the stable nitroxyl radical (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO), resulting in oxidative addition to generate bismuth(III) complexes. In the latter case, the isolated reaction products, Bi(NONR)(OTEMP), were used to access the catalytic coupling of TEMPO and phenylsilane. Subsequent investigations into the reactivity of the bismuth(II) species revealed the selective activation of white phosphorus (P4) and terminal aromatic alkynes by •Bi(NONAr), generating the bismuth(III) complexes [Bi(NONAr)]2(P4) and [Bi(NONR)]2(HC=C(C6H4-4-X)), respectively. In both cases, a temperature dependent equilibrium is observed. In contrast, the dibismuthane [Bi(NONtBu)]2 and more encumbered bismuth radical •Bi(NONAr‡) do not react with these substrates, demonstrating the importance of the nature of the bismuth centre (i.e. dibismuthane vs. bismuth radical) and ligand bulk on the reactivity of these systems.  Chapter 4 describes the synthesis and characterisation of a series of low oxidation state antimony compounds. A series of distibanes supported by the (NONR)-framework were prepared from the reaction of antimony(III) chloride species Sb(NONR)Cl with magnesium(I) reducing agents [(BDIAr§)Mg]2 (Ar§ = 2,4,6-Me3C6H3 or Ar). When R = tBu, Ph or 2,6-Me2C6H3 (Ar’), a distibane [Sb(NONR)]2 is obtained, featuring a Sb-Sb single bond. While the tBu and Ph derivatives contained typical Sb-Sb single bonds, the bonding in the Ar’ derivative is elongated, significantly longer than in all other reported distibanes. The weakness of this bond is highlighted in a reaction with P4, which shows activation of the P4 tetrahedron and P-P bond cleavage. In contrast, reduction of the bulkier Ar derivative (Ar = 2,6-iPr2C6H3) with the magnesium(I) reagents results in formation of the distibene [Sb(NONR)Mg(BDIAr§)]2, featuring a Sb=Sb bond.  Chapter 5 describes the synthesis and characterisation of low oxidation state indium compounds supported by the (NONAr)-ligand. A number of indium(III) chloride species supported by either the (NONAr)-ligand or the retro-Brook rearranged (NNOAr)-ligand (NNOAr = [RN{Me2SiO}{Me2SiN(R)}) were synthesised. In all cases, an equivalent of lithium chloride was retained in the molecular structure, allowing isolation of the indate complexes In(NONAr)(μ-Cl)2Li(Et2O)2, [Li(THF)4][In(NONAr)Cl2] and In(NNOAr.Li(THF)3)Cl2. Attempts to reduce these complexes using a hydride source were unsuccessful, instead yielding the corresponding indium(III) hydride species [Li(THF)4][In(NONAr)H2] and In(NNOAr.Li(THF)3)H2, respectively. Reduction of the (NONAr)-supported indium(III) chloride complexes using alkali reducing agents allowed access to the diindane [In(NONAr)]2, featuring an In-In single bond, and the first example of an anionic N-heterocyclic indene. The latter species is isovalent with N-heterocyclic carbenes and is a potential pre-cursor for indium-metal bonding formation. In addition, this compound is of interest as a source of nucleophilic indium.  Finally, Chapter 6 provides a summary of the results presented in this thesis and a brief overview of the future direction of this field of research.</p>


2021 ◽  
Author(s):  
◽  
Ryan Schwamm

<p>The work presented in this thesis describes the synthesis and stabilisation of heavy p-block elements (defined herein as being those with 5s/p and 6s/p valence electrons) in low oxidation states using sterically demanding ligands based on a di(amido)siloxane framework ([(O{SiMe2N(R)}2]2-, abbrev. [(NONR)]2-).  Chapter 1 gives a general introduction to the heavy p-block elements and discusses a number of concepts that define the molecular chemistry of these elements. A brief introduction into low oxidation state main group chemistry is provided and the importance of sterically demanding ligands in this field of research is introduced. The di(amido)siloxane ligand framework utilised in this work is introduced, with common coordination modes and characteristic properties discussed.  Chapter 2 discusses the chemistry of low oxidation state bismuth complexes and follows a recent report by our group on the first structurally authenticated bismuth(II) radical •Bi(NONAr). The synthesis of a series of bismuth(III) monochloride species Bi(NONR)Cl (R = tBu, Ph, 2,6-Me2C6H3 (Ar’), 2,6-iPr2C6H3 (Ar) and 2,6-(CHPh2)2-4-tBu-C6H2 (Ar‡)) is discussed, and the steric properties of the ligand systems evaluated. In the case of the R = tBu and Ar‡ derivatives, reduction of the bismuth(III) monochloride gave the dibismuthane [Bi(NONtBu)]2 and bismuth(II) radical •Bi(NONAr‡), respectively. Further reduction of the bismuth centres resulted in the formation of rare and unprecedented multimetallic bismuth compounds containing [Bin]n+ cores. These include the Bi4 cluster compound Bi4(NONAr)2, in which the bismuth atoms exist in an unprecedented mixed valent arrangement and may be assigned oxidation states of 0, +1 or +2, and the tribismuthane cluster [Bi3(NONtBu)2]-, which features the first structurally characterised Bi3 chain. The utility of the di(amido) ligand plays a key role in the formation of many of these compounds, with Bi-N bond cleavage suggested to be a key step in many of the reaction pathways.  Chapter 3 discusses the reactivity of the bismuth(II) complexes [Bi(NONtBu)]2, •Bi(NONAr) and •Bi(NONAr‡) which feature either a Bi-Bi bond or a bismuth-centred radical. Initial experiments parallel reported reactivity with halogen radical sources (N-bromosuccinimide or iodine), chalcogens (S, Se, Te) and the stable nitroxyl radical (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO), resulting in oxidative addition to generate bismuth(III) complexes. In the latter case, the isolated reaction products, Bi(NONR)(OTEMP), were used to access the catalytic coupling of TEMPO and phenylsilane. Subsequent investigations into the reactivity of the bismuth(II) species revealed the selective activation of white phosphorus (P4) and terminal aromatic alkynes by •Bi(NONAr), generating the bismuth(III) complexes [Bi(NONAr)]2(P4) and [Bi(NONR)]2(HC=C(C6H4-4-X)), respectively. In both cases, a temperature dependent equilibrium is observed. In contrast, the dibismuthane [Bi(NONtBu)]2 and more encumbered bismuth radical •Bi(NONAr‡) do not react with these substrates, demonstrating the importance of the nature of the bismuth centre (i.e. dibismuthane vs. bismuth radical) and ligand bulk on the reactivity of these systems.  Chapter 4 describes the synthesis and characterisation of a series of low oxidation state antimony compounds. A series of distibanes supported by the (NONR)-framework were prepared from the reaction of antimony(III) chloride species Sb(NONR)Cl with magnesium(I) reducing agents [(BDIAr§)Mg]2 (Ar§ = 2,4,6-Me3C6H3 or Ar). When R = tBu, Ph or 2,6-Me2C6H3 (Ar’), a distibane [Sb(NONR)]2 is obtained, featuring a Sb-Sb single bond. While the tBu and Ph derivatives contained typical Sb-Sb single bonds, the bonding in the Ar’ derivative is elongated, significantly longer than in all other reported distibanes. The weakness of this bond is highlighted in a reaction with P4, which shows activation of the P4 tetrahedron and P-P bond cleavage. In contrast, reduction of the bulkier Ar derivative (Ar = 2,6-iPr2C6H3) with the magnesium(I) reagents results in formation of the distibene [Sb(NONR)Mg(BDIAr§)]2, featuring a Sb=Sb bond.  Chapter 5 describes the synthesis and characterisation of low oxidation state indium compounds supported by the (NONAr)-ligand. A number of indium(III) chloride species supported by either the (NONAr)-ligand or the retro-Brook rearranged (NNOAr)-ligand (NNOAr = [RN{Me2SiO}{Me2SiN(R)}) were synthesised. In all cases, an equivalent of lithium chloride was retained in the molecular structure, allowing isolation of the indate complexes In(NONAr)(μ-Cl)2Li(Et2O)2, [Li(THF)4][In(NONAr)Cl2] and In(NNOAr.Li(THF)3)Cl2. Attempts to reduce these complexes using a hydride source were unsuccessful, instead yielding the corresponding indium(III) hydride species [Li(THF)4][In(NONAr)H2] and In(NNOAr.Li(THF)3)H2, respectively. Reduction of the (NONAr)-supported indium(III) chloride complexes using alkali reducing agents allowed access to the diindane [In(NONAr)]2, featuring an In-In single bond, and the first example of an anionic N-heterocyclic indene. The latter species is isovalent with N-heterocyclic carbenes and is a potential pre-cursor for indium-metal bonding formation. In addition, this compound is of interest as a source of nucleophilic indium.  Finally, Chapter 6 provides a summary of the results presented in this thesis and a brief overview of the future direction of this field of research.</p>


Minerals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1286
Author(s):  
Marcus Sommerfeld ◽  
Bernd Friedrich

The production of ferroalloys and alloys like ferronickel, ferrochromium, ferromanganese, silicomanganese, ferrosilicon and silicon is commonly carried out in submerged arc furnaces. Submerged arc furnaces are also used to upgrade ilmenite by producing pig iron and a titania-rich slag. Metal containing resources are smelted in this furnace type using fossil carbon as a reducing agent, which is responsible for a large amount of direct CO2 emissions in those processes. Instead, renewable bio-based carbon could be a viable direct replacement of fossil carbon currently investigated by research institutions and companies to lower the CO2 footprint of produced alloys. A second option could be the usage of hydrogen. However, hydrogen has the disadvantages that current production facilities relying on solid reducing agents need to be adjusted. Furthermore, hydrogen reduction of ignoble metals like chromium, manganese and silicon is only possible at very low H2O/H2 partial pressure ratios. The present article is a comprehensive review of the research carried out regarding the utilization of bio-based carbon for the processing of the mentioned products. Starting with the potential impact of the ferroalloy industry on greenhouse gas emissions, followed by a general description of bio-based reducing agents and unit operations covered by this review, each following chapter presents current research carried out to produce each metal. Most studies focused on pre-reduction or solid-state reduction except the silicon industry, which instead had a strong focus on smelting up to an industrial-scale and the design of bio-based carbon for submerged arc furnace processes. Those results might be transferable to other submerged arc furnace processes as well and could help to accelerate research to produce other metals. Deviations between the amount of research and scale of tests for the same unit operation but different metal resources were identified and closer cooperation could be helpful to transfer knowledge from one area to another. Life cycle assessment to produce ferronickel and silicon already revealed the potential of bio-based reducing agents in terms of greenhouse gas emissions, but was not carried out for other metals until now.


2021 ◽  
Author(s):  
◽  
Sujay Prabakar

<p>This thesis is concerned with the synthesis and characterization of nanostructured materials in the solution, in particular silicon and germanium nanocrystals, their applica-tion as fluorescent whitening agents and titanium disulphide nanostructures. The aim of this research with regards to the synthesis of silicon and germanium nanocrystals was to obtain size control and provide functionality using simple room temperature solution techniques. In the case of the nanostructures of titanium disulphide, the focus was to synthesize in the colloid using simple one-pot bench top techniques. The above were realized with chemical techniques in the solution using organic solvents and surfactants to control their size. The morphology, chemical composition and crystal structure of the synthesized nanomaterials were characterized using techniques such as High Resolution Transmission Electron Microscopy (HRTEM), Selected Area Electron Diffraction (SAED), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectrosco-py (EDX) and Optical Spectroscopies. Whilst chapter one is a brief introduction of the thesis, chapter two talks in detail about the various characterization techniques used in this research.  Chapter three of the thesis focuses on the synthesis of alkyl- and amine-functionalized silicon nanocrystals using a microemlusion technique. The effect of reducing agents, surfactants and precursors on particle size was studied. The surfactant C12E5 was found to be very effective in producing silicon nanocrystals that were freestanding and pure. Whilst the hydride reducing agents lithium aluminium hydride and lithium tri-ethyl borohydride were found to be effective in synthesizing nanocrystals of narrow size distribution, it was found that using silicon tetrachloride yielded smaller particles compared to silicon tetrabromide.  The fourth chapter in the theses is concerned with the synthesis and characterization of germanium nanocrystals by both microemulsion and high temperature techniques. Using lithium aluminium hydride; a strong reducing agent, very small nanocrystals were obtained, whilst weaker reductants such as sodium borohydride produced larger nano-crystals. Another effective method to control the particle size of germanium nanocrystals was found to be by varying the concentration of precursor. The germanium nanocrystals which were amine capped were found to luminesce in the blue and were used to image HePG2 cells. Toxicity studies on these nanocrystals proved their relative non-toxicity. The high temperature experiments, though not as flexible as the room temperature syntheses were found to facilitate a certain degree of size control.  Chapter five of the theses deal with the application of silicon and germanium nanocrys-tals as fluorescent whitening agents in wool fabrics. Both nanocrystals, when applied to the fabric were found to emit matching blue fluorescence that was demonstrated to be more suited to improving the brightness properties of fabric than the commercial fluo-rescing whitening agent Uvitex. In particular Silicon-amine and Silicon-hexene functionalized nanocrystal (low concentration) treated fabrics were found to have improved color stability against both UVA and UVB radiation. The treated fabrics were in addition found to maintain a stable color than untreated fabric. Silicon-amine treated fabrics were found to have a stable color even after 48h exposures to UVA radiation. It should be noted that this is the first evidence of the application of group IV semiconductor nanocrystals as fluorescing whitening agents.  The sixth chapter of this thesis deals with the one-pot synthesis of titanium disulphide nanostructures using both coordinating and non-coordinating solvents and their subse-quent characterization. By varying the injection temperature of the titanium source into the 1-Octadecene sulphur solution, two different morphologies were synthesized. Two different pathways were suggested for the formation of the flower-like and flake-like morphologies; an instant nucleation to form titanium disulphide flakes whilst spherical nuclei to form flower-like nanostructures. The flower-like nanostructures were found to have higher BET surface area compared to the flake-like nanostructures and previously reported surface areas for analogous TiS₂ nanostructures. Whilst using oleylamine as solvent, the low temperature injection yielded hollow spheres of TiS₂ and the high temperature injection, fullerene-like nanoparticles of TiS₂. The property of oleylamine to selectively bind to the nanostructure surface in conjunction with the effect of injection temperature was understood to be behind the growth of these nanostructures. The synthesis of flower-like and flake-like morphologies by solution phase techniques were the first evidence of this kind for titanium disulphide and provides a new and exciting material for a variety of applications.  A final chapter on conclusions and recommendations for future work is then presented.</p>


2021 ◽  
Author(s):  
◽  
Elliot Borren

<p>Rising levels of carbon dioxide (CO₂) in the atmosphere has led to metal amide and alkoxide complexes being explored as potential CO₂ activators. A wide variety of M–O and M–N bonds have been shown to activate CO₂, however to date there are no examples with cadmium. A range of novel cadmium amide and alkoxide complexes have been synthesised, using the β-diketiminato ligand (BDI) as an ancilliary ligand. Initial reactivity studies have suggested CO₂ activation may be possible, although no products were isolated. Homonuclear metallic bonding (M–M) has been explored since the 1950’s and complexes containing M–M bonds are known for almost all transition and main group metals. There are only two reported Cd–Cd bonds, both using sterically bulky monoanionic ligands, like the β-diketiminato ligand. A novel β-diketiminato-cadmium chloride complex was synthesised and treated with a range of different reducing agents to generate a Cd–Cd bond. Different reactivities were observed for the reducing agents, however evidence of a Cd–Cd bond was not obtained. Group 14-16 materials, such as lead selenide, are p-type semi-conductors and have the potential to replacing silicon as a photon acceptor in solar cells. Lead selenide nanoparticles display quantum confinement effects, which allows one to tailor the band gap energies to maximise their absorbance of solar energy. The synthesis of PbSe nanoparticles is described in this study from the reaction between selenium and the lead complex [(BDIph)₂Pb], as well as from the decomposition of [(BDIdipp)PbSeP{Se}Cy₂]. Differences in the size and shapes of the nanoparticles was observed, highlighting the need for controlled nucleation and growth conditions.</p>


2021 ◽  
Author(s):  
◽  
Sujay Prabakar

<p>This thesis is concerned with the synthesis and characterization of nanostructured materials in the solution, in particular silicon and germanium nanocrystals, their applica-tion as fluorescent whitening agents and titanium disulphide nanostructures. The aim of this research with regards to the synthesis of silicon and germanium nanocrystals was to obtain size control and provide functionality using simple room temperature solution techniques. In the case of the nanostructures of titanium disulphide, the focus was to synthesize in the colloid using simple one-pot bench top techniques. The above were realized with chemical techniques in the solution using organic solvents and surfactants to control their size. The morphology, chemical composition and crystal structure of the synthesized nanomaterials were characterized using techniques such as High Resolution Transmission Electron Microscopy (HRTEM), Selected Area Electron Diffraction (SAED), Scanning Electron Microscopy (SEM), Energy Dispersive X-Ray Spectrosco-py (EDX) and Optical Spectroscopies. Whilst chapter one is a brief introduction of the thesis, chapter two talks in detail about the various characterization techniques used in this research.  Chapter three of the thesis focuses on the synthesis of alkyl- and amine-functionalized silicon nanocrystals using a microemlusion technique. The effect of reducing agents, surfactants and precursors on particle size was studied. The surfactant C12E5 was found to be very effective in producing silicon nanocrystals that were freestanding and pure. Whilst the hydride reducing agents lithium aluminium hydride and lithium tri-ethyl borohydride were found to be effective in synthesizing nanocrystals of narrow size distribution, it was found that using silicon tetrachloride yielded smaller particles compared to silicon tetrabromide.  The fourth chapter in the theses is concerned with the synthesis and characterization of germanium nanocrystals by both microemulsion and high temperature techniques. Using lithium aluminium hydride; a strong reducing agent, very small nanocrystals were obtained, whilst weaker reductants such as sodium borohydride produced larger nano-crystals. Another effective method to control the particle size of germanium nanocrystals was found to be by varying the concentration of precursor. The germanium nanocrystals which were amine capped were found to luminesce in the blue and were used to image HePG2 cells. Toxicity studies on these nanocrystals proved their relative non-toxicity. The high temperature experiments, though not as flexible as the room temperature syntheses were found to facilitate a certain degree of size control.  Chapter five of the theses deal with the application of silicon and germanium nanocrys-tals as fluorescent whitening agents in wool fabrics. Both nanocrystals, when applied to the fabric were found to emit matching blue fluorescence that was demonstrated to be more suited to improving the brightness properties of fabric than the commercial fluo-rescing whitening agent Uvitex. In particular Silicon-amine and Silicon-hexene functionalized nanocrystal (low concentration) treated fabrics were found to have improved color stability against both UVA and UVB radiation. The treated fabrics were in addition found to maintain a stable color than untreated fabric. Silicon-amine treated fabrics were found to have a stable color even after 48h exposures to UVA radiation. It should be noted that this is the first evidence of the application of group IV semiconductor nanocrystals as fluorescing whitening agents.  The sixth chapter of this thesis deals with the one-pot synthesis of titanium disulphide nanostructures using both coordinating and non-coordinating solvents and their subse-quent characterization. By varying the injection temperature of the titanium source into the 1-Octadecene sulphur solution, two different morphologies were synthesized. Two different pathways were suggested for the formation of the flower-like and flake-like morphologies; an instant nucleation to form titanium disulphide flakes whilst spherical nuclei to form flower-like nanostructures. The flower-like nanostructures were found to have higher BET surface area compared to the flake-like nanostructures and previously reported surface areas for analogous TiS₂ nanostructures. Whilst using oleylamine as solvent, the low temperature injection yielded hollow spheres of TiS₂ and the high temperature injection, fullerene-like nanoparticles of TiS₂. The property of oleylamine to selectively bind to the nanostructure surface in conjunction with the effect of injection temperature was understood to be behind the growth of these nanostructures. The synthesis of flower-like and flake-like morphologies by solution phase techniques were the first evidence of this kind for titanium disulphide and provides a new and exciting material for a variety of applications.  A final chapter on conclusions and recommendations for future work is then presented.</p>


2021 ◽  
Author(s):  
◽  
Elliot Borren

<p>Rising levels of carbon dioxide (CO₂) in the atmosphere has led to metal amide and alkoxide complexes being explored as potential CO₂ activators. A wide variety of M–O and M–N bonds have been shown to activate CO₂, however to date there are no examples with cadmium. A range of novel cadmium amide and alkoxide complexes have been synthesised, using the β-diketiminato ligand (BDI) as an ancilliary ligand. Initial reactivity studies have suggested CO₂ activation may be possible, although no products were isolated. Homonuclear metallic bonding (M–M) has been explored since the 1950’s and complexes containing M–M bonds are known for almost all transition and main group metals. There are only two reported Cd–Cd bonds, both using sterically bulky monoanionic ligands, like the β-diketiminato ligand. A novel β-diketiminato-cadmium chloride complex was synthesised and treated with a range of different reducing agents to generate a Cd–Cd bond. Different reactivities were observed for the reducing agents, however evidence of a Cd–Cd bond was not obtained. Group 14-16 materials, such as lead selenide, are p-type semi-conductors and have the potential to replacing silicon as a photon acceptor in solar cells. Lead selenide nanoparticles display quantum confinement effects, which allows one to tailor the band gap energies to maximise their absorbance of solar energy. The synthesis of PbSe nanoparticles is described in this study from the reaction between selenium and the lead complex [(BDIph)₂Pb], as well as from the decomposition of [(BDIdipp)PbSeP{Se}Cy₂]. Differences in the size and shapes of the nanoparticles was observed, highlighting the need for controlled nucleation and growth conditions.</p>


Author(s):  
Yeawan Lee ◽  
Jin-Ho Sung ◽  
Bangwoo Han ◽  
Yong-Jin Kim ◽  
Hak-Joon Kim

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