No description available.

No description available.

The Atlantis II Deep is a location of modern submarine hydrothermal activity along the slowly spreading Red Sea rift axis. Venting of high-temperature hydrothermal fluids, similar to those associated with black smokers, takes place in a brine pool and has led to the accumulation of 90 Mt (dry, salt free) of stratiform, metalliferous sediment. The conditions of mineralization are unique in the modern oceans, but have been widely suggested as a possible analog of some important ancient stratiform base metal ore deposits. This study shows that many of the proposed genetic models for these ancient deposits may be highly simplified and do not take into account rapid diagenetic transformations, widespread non-equilibrium processes, and many other aspects of metal deposition. Sediment cores of the Atlantis II muds were last studied more than 30 years ago. High-resolution sampling and careful re-examination of the mineralogy and geochemistry of the sediments, using modern analytical techniques has significantly improved the understanding of the different processes responsible for the formation of the finely layered metallifeous sediments. The geochemistry of the individual layers is controlled by highly variable detrital, hydrogenic and hydrothermal input. Primary depositional pathways from the brine pool are the main control on basin-wide metal distribution (e.g., increasing Cu/Zn away from the vents) including variable enrichment in trace metals via scavenging from the brine pool and from the enriched pore waters. Cu and Zn have been deposited not only as sulfides but also with poorly crystalline Si-Fe-(oxy)hydroxides. A significant proportion of the original non-sulfide Cu and Zn are diagenetically transformed into sulfides, but also carbonates and clays, in large part reflecting sulfide deficient pore waters. Negative δ34S values, previously unrecognized in the sulfide- and metal-rich units, indicate a source of bacteriogenic sulfide. Syn-diagenetic processes also appear to have been responsible for the sharp laminations in the sediments, as well as distinctive zoning of carbonate and clay minerals around the vent source. The early diagenetic transformations observed in the Atlantis II Deep may not be preserved in the ancient rock record but nevertheless have important implications for metal deposition in some of the world’s largest and richest base metal ore deposits.

Die Existenz metallreicher Perowskite der Zusammensetzung (SE3X)M (X = O, N; SE = La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Er, Ho, Tm, Lu; M = Al, Ga, In, Sn) wurde untersucht. Die Charakterisierung der Proben erfolgte mit Röntgenpulverdiffraktometrie und Elementaranalysen (O und N). Oxide (SE3O)Al mit SE = La, Ce, Pr, Nd und Sm und (SE3O)In mit SE = Ce, Pr und Nd wurden erhalten. Die Reihe der Verbindungen (SE3N)Al (SE = La, Ce, Pr, Nd, Sm) wurde um die Seltenerd-Metalle SE = Gd, Tb, Dy, Ho, Er und Tm erweitert. Die metallreichen Perowskite (SE3N)Sn (SE = La, Ce, Pr, Sm) und (SE3N)Ga (SE = Ce, Pr, Sm, Gd, Tb) wurden erstmals beschrieben. Die thermische Stabilität (DSC) der Phasen (SE3X)M ist für die Nitride allgemein am höchsten. Nitride von Al und Ga zersetzen zwischen 1000 °C und 1200 °C, Stannide bleiben bis 1250 °C thermisch stabil. Messungen der magnetischen Suszeptibilität und der LIII-Absorbtionskanten sind in Einklang mit einer Elektronenkonfiguration SE3+. Die gemessenen elektrischen Widerstände sind charakteristisch für schlechte metallische Leiter. Verschiedene Gehaltschnitte SE3Al-(SE3X)Al und SE3In-(SE3X)In wurden mit Röntgenpulverdiffraktometrie und DTA untersucht. Die Oxide und Nitride (SE3X1-y)M (SE = La, Ce; X = N, O) weisen nur geringe Phasenbreiten auf. Die Carbide (Ce3C1-y)In zeigen hingegen signifikante Phasenbreiten. In den Systemen EA-In-N wurden röntgenografisch phasenreine Pulver von (Ca4N)[In]2 und (EA19N7)[In4]2 (EA = Ca, Sr) erhalten. Durch Elementaranalysen auf H, C, N, O, EA und In und Neutronenbeugung am Pulver können alternative Zusammensetzungen mit einer ausgeglichenen Ladungsbilanz im Sinne des Zintl-Konzepts für diese Phasen ausgeschlossen werden. Im System La-Al wurde die neue Phase La16Al13 beobachtet und an Einkristallen sowie an Pulvern charakterisiert. Das in der Literatur im Cu3Au-Strukturtyp beschrieben kubische Polymorph von Ce3Al wurde auf einen ternären metallreichen Perowskit (Ce3X)Al zurückgeführt.

Chemical synthesis of materials is facing enormous challenges at the present time. The necessary transition toward more sustainable economic processes requires new materials as well as optimized production of well-established materials. However, inorganic materials (e.g., ceramics or alloys) are typically produced industrially by high-temperature processes at up to 2000 °C. A relatively new approach for inorganic synthesis is based on so-called ionic liquids. Ionic liquids (ILs) — often defined as salts with melting points below 100 °C[1] — are usually composed of sterically demanding organic cations and (often) polyatomic anions, which can be selected in order to tune the properties of the IL. Owing to the distinctive physicochemical properties of ILs (e.g., wide liquidus range, high redox and thermal stability, (usually) negligible vapor pressure, tunable polarity), they have gained interest for a wide range of applications. Among the numerous inorganic materials accessible in ILs have been remarkable examples, especially in main-group element chemistry. For instance, a new metastable modification of germanium in the clathrate-II structure[2] or the largest known naked, main-group element cluster [Sn36Ge24Se132]24– (“Zeoball”).[3] The introduction of Lewis-acidic ILs has enhanced the convenience of polycation syntheses and enabled substitution of carcinogenic or toxic substances like benzene, SO2, or AsF5.[4] A considerable number of polycations of group 15 or 16 elements has been synthesized in ILs. The utilization of an IL as reaction medium can be decisive for the composition, structure, and physical properties of the (polycationic) reaction product.[5] In order to broaden the knowledge on synthesis techniques for inorganic materials near ambient temperature based on ILs, this thesis aimed at two goals: • Explorative synthesis of new inorganic compounds in ILs • Elucidating the influence of ILs on product formation For these two goals, metal-rich (polycationic) compounds of group 15 were chosen as promising chemical system, owing to the effectiveness of alkylimidazolium-based Lewis-acidic ILs for the synthesis of this class of compounds. A variety of new polycationic compounds has been successfully synthesized in Lewis-acidic ILs based on 1-n-butyl-3-methylimidazolium (or 1-ethy-3-methylimidazolium) halides and halogenido-aluminates. Determination of the crystal structures by single-crystal X-ray diffraction enabled analysis of their bonding situation supported by quantum-chemical calculations. In general, the employed ILs enabled syntheses with a high selectivity for the yielded polycation. Depending on the investigated chemical system, the following parameters were pinpointed to have significant influence: • Choice of starting materials • Choice of cation as well as anion of the IL • Reaction temperature • Concentration of starting materials in the IL The investigations were supported by NMR spectroscopy, which led to the discovery of nanoparticles of red phosphorus. This finding may stimulate the development of an easily accessible, reactive form of phosphorus without the hazardous drawbacks of the white allotrope. In addition, in situ NMR measurements in ILs were proven a viable option for mechanistic investigations. Conventional solid-state reaction as well as ionothermal syntheses yielded the new layered compounds M2Bi2S3(AlCl4)2 (M = Cu, Ag), which can be interpreted as Bi2S3 molecules embedded in MAlCl4 salts. The choice of starting materials was found to have a crucial influence on the crystallized polytype. Omitting the IL hindered the formation of crystals suitable for single-crystal structure determination. The three new main-group element heteropolycations [Bi6Te4Br2]4+, [Bi3S4AlCl]3+, and [Sb13Se16]7+ as well as known [Bi4Te4]4+ has been synthesized under ionothermal conditions. The Lewis-acidic ILs proved to be exceptional solvents for elements and their halides, and likewise for Bi2S3 and Bi2Te3. Hence, these solvents are not only advantageous reaction media for pnictogen and chalcogen chemistry but also potential (selective but expensive) ore-processing agents. These excellent solvent capabilities extend to complex ternary compounds including heavy transition metals such as Bi16PdCl22 and elemental platinum. This gave rise to the synthesis of metal-rich salts containing [Bi10]4+ antiprisms with an endohedral palladium or, for the first time, platinum atom. Furthermore, the filled bismuth polycation [Rh@Bi9]4+ or the complex cluster [Rh2Bi12]4+ could be obtained from dissolution and conversion of Bi12−xRhX13–x (X = Cl, Br) depending on the employed IL. Real-space bonding analysis revealed that [Rh2Bi12]4+ acquires a unique standing between dative bonding by bismuth polyions and mixed clusters following Wade-Mingos rules. References [1] J. S. Wilkes, P. Wasserscheid, T. Welton, in Ionic Liquids in Synthesis (Eds.: P. Wasserscheid, T. Welton), Wiley-VCH Verlag GmbH & Co. KGaA, 2007, pp. 1–6. [2] A. M. Guloy, R. Ramlau, Z. Tang, W. Schnelle, M. Baitinger, Y. Grin, Nature 2006, 443, 320–323. [3] Y. Lin, W. Massa, S. Dehnen, J. Am. Chem. Soc. 2012, 134, 4497–4500. [4] E. Ahmed, D. Köhler, M. Ruck, Z. Anorg. Allg. Chem. 2009, 635, 297–300. [5] E. Ahmed, J. Beck, J. Daniels, T. Doert, S. J. Eck, A. Heerwig, A. Isaeva, S. Lidin, M. Ruck, W. Schnelle, et al., Angew. Chem. 2012, 124, 8230–8233; Angew. Chem. Int. Ed. 2012, 51, 8106–8109.

Chemical synthesis of materials is facing enormous challenges at the present time. The necessary transition toward more sustainable economic processes requires new materials as well as optimized production of well-established materials. However, inorganic materials (e.g., ceramics or alloys) are typically produced industrially by high-temperature processes at up to 2000 °C. A relatively new approach for inorganic synthesis is based on so-called ionic liquids. Ionic liquids (ILs) — often defined as salts with melting points below 100 °C[1] — are usually composed of sterically demanding organic cations and (often) polyatomic anions, which can be selected in order to tune the properties of the IL. Owing to the distinctive physicochemical properties of ILs (e.g., wide liquidus range, high redox and thermal stability, (usually) negligible vapor pressure, tunable polarity), they have gained interest for a wide range of applications. Among the numerous inorganic materials accessible in ILs have been remarkable examples, especially in main-group element chemistry. For instance, a new metastable modification of germanium in the clathrate-II structure[2] or the largest known naked, main-group element cluster [Sn36Ge24Se132]24– (“Zeoball”).[3] The introduction of Lewis-acidic ILs has enhanced the convenience of polycation syntheses and enabled substitution of carcinogenic or toxic substances like benzene, SO2, or AsF5.[4] A considerable number of polycations of group 15 or 16 elements has been synthesized in ILs. The utilization of an IL as reaction medium can be decisive for the composition, structure, and physical properties of the (polycationic) reaction product.[5] In order to broaden the knowledge on synthesis techniques for inorganic materials near ambient temperature based on ILs, this thesis aimed at two goals: • Explorative synthesis of new inorganic compounds in ILs • Elucidating the influence of ILs on product formation For these two goals, metal-rich (polycationic) compounds of group 15 were chosen as promising chemical system, owing to the effectiveness of alkylimidazolium-based Lewis-acidic ILs for the synthesis of this class of compounds. A variety of new polycationic compounds has been successfully synthesized in Lewis-acidic ILs based on 1-n-butyl-3-methylimidazolium (or 1-ethy-3-methylimidazolium) halides and halogenido-aluminates. Determination of the crystal structures by single-crystal X-ray diffraction enabled analysis of their bonding situation supported by quantum-chemical calculations. In general, the employed ILs enabled syntheses with a high selectivity for the yielded polycation. Depending on the investigated chemical system, the following parameters were pinpointed to have significant influence: • Choice of starting materials • Choice of cation as well as anion of the IL • Reaction temperature • Concentration of starting materials in the IL The investigations were supported by NMR spectroscopy, which led to the discovery of nanoparticles of red phosphorus. This finding may stimulate the development of an easily accessible, reactive form of phosphorus without the hazardous drawbacks of the white allotrope. In addition, in situ NMR measurements in ILs were proven a viable option for mechanistic investigations. Conventional solid-state reaction as well as ionothermal syntheses yielded the new layered compounds M2Bi2S3(AlCl4)2 (M = Cu, Ag), which can be interpreted as Bi2S3 molecules embedded in MAlCl4 salts. The choice of starting materials was found to have a crucial influence on the crystallized polytype. Omitting the IL hindered the formation of crystals suitable for single-crystal structure determination. The three new main-group element heteropolycations [Bi6Te4Br2]4+, [Bi3S4AlCl]3+, and [Sb13Se16]7+ as well as known [Bi4Te4]4+ has been synthesized under ionothermal conditions. The Lewis-acidic ILs proved to be exceptional solvents for elements and their halides, and likewise for Bi2S3 and Bi2Te3. Hence, these solvents are not only advantageous reaction media for pnictogen and chalcogen chemistry but also potential (selective but expensive) ore-processing agents. These excellent solvent capabilities extend to complex ternary compounds including heavy transition metals such as Bi16PdCl22 and elemental platinum. This gave rise to the synthesis of metal-rich salts containing [Bi10]4+ antiprisms with an endohedral palladium or, for the first time, platinum atom. Furthermore, the filled bismuth polycation [Rh@Bi9]4+ or the complex cluster [Rh2Bi12]4+ could be obtained from dissolution and conversion of Bi12−xRhX13–x (X = Cl, Br) depending on the employed IL. Real-space bonding analysis revealed that [Rh2Bi12]4+ acquires a unique standing between dative bonding by bismuth polyions and mixed clusters following Wade-Mingos rules. References [1] J. S. Wilkes, P. Wasserscheid, T. Welton, in Ionic Liquids in Synthesis (Eds.: P. Wasserscheid, T. Welton), Wiley-VCH Verlag GmbH & Co. KGaA, 2007, pp. 1–6. [2] A. M. Guloy, R. Ramlau, Z. Tang, W. Schnelle, M. Baitinger, Y. Grin, Nature 2006, 443, 320–323. [3] Y. Lin, W. Massa, S. Dehnen, J. Am. Chem. Soc. 2012, 134, 4497–4500. [4] E. Ahmed, D. Köhler, M. Ruck, Z. Anorg. Allg. Chem. 2009, 635, 297–300. [5] E. Ahmed, J. Beck, J. Daniels, T. Doert, S. J. Eck, A. Heerwig, A. Isaeva, S. Lidin, M. Ruck, W. Schnelle, et al., Angew. Chem. 2012, 124, 8230–8233; Angew. Chem. Int. Ed. 2012, 51, 8106–8109.

Die Existenz metallreicher Perowskite der Zusammensetzung (SE3X)M (X = O, N; SE = La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Er, Ho, Tm, Lu; M = Al, Ga, In, Sn) wurde untersucht. Die Charakterisierung der Proben erfolgte mit Röntgenpulverdiffraktometrie und Elementaranalysen (O und N). Oxide (SE3O)Al mit SE = La, Ce, Pr, Nd und Sm und (SE3O)In mit SE = Ce, Pr und Nd wurden erhalten. Die Reihe der Verbindungen (SE3N)Al (SE = La, Ce, Pr, Nd, Sm) wurde um die Seltenerd-Metalle SE = Gd, Tb, Dy, Ho, Er und Tm erweitert. Die metallreichen Perowskite (SE3N)Sn (SE = La, Ce, Pr, Sm) und (SE3N)Ga (SE = Ce, Pr, Sm, Gd, Tb) wurden erstmals beschrieben. Die thermische Stabilität (DSC) der Phasen (SE3X)M ist für die Nitride allgemein am höchsten. Nitride von Al und Ga zersetzen zwischen 1000 °C und 1200 °C, Stannide bleiben bis 1250 °C thermisch stabil. Messungen der magnetischen Suszeptibilität und der LIII-Absorbtionskanten sind in Einklang mit einer Elektronenkonfiguration SE3+. Die gemessenen elektrischen Widerstände sind charakteristisch für schlechte metallische Leiter. Verschiedene Gehaltschnitte SE3Al-(SE3X)Al und SE3In-(SE3X)In wurden mit Röntgenpulverdiffraktometrie und DTA untersucht. Die Oxide und Nitride (SE3X1-y)M (SE = La, Ce; X = N, O) weisen nur geringe Phasenbreiten auf. Die Carbide (Ce3C1-y)In zeigen hingegen signifikante Phasenbreiten. In den Systemen EA-In-N wurden röntgenografisch phasenreine Pulver von (Ca4N)[In]2 und (EA19N7)[In4]2 (EA = Ca, Sr) erhalten. Durch Elementaranalysen auf H, C, N, O, EA und In und Neutronenbeugung am Pulver können alternative Zusammensetzungen mit einer ausgeglichenen Ladungsbilanz im Sinne des Zintl-Konzepts für diese Phasen ausgeschlossen werden. Im System La-Al wurde die neue Phase La16Al13 beobachtet und an Einkristallen sowie an Pulvern charakterisiert. Das in der Literatur im Cu3Au-Strukturtyp beschrieben kubische Polymorph von Ce3Al wurde auf einen ternären metallreichen Perowskit (Ce3X)Al zurückgeführt.

No description available.

No description available.

No description available.