This compilation dissertation consists of four essays with the common theme of welfare analysis of long-term public investments. The first two essays focus on analysis of climate change mitigation, i.e., the social cost of carbon dioxide. The third essay focuses on cost-benefit analysis (CBA) of transport investment projects, while the last essay takes a broader perspective on welfare analysis. Essay 1: The Temporal Aspects of the Social Cost of Greenhouse Gases. The purpose of Essay 1 is to investigate the temporal aspects of the social cost of greenhouse gases. I find that the calculation period should ultimately be modeled to be consistent with the discount rate and that the “global-warming potential” concept is unsuitable for calculation of the social cost of GHGs other than carbon dioxide. Essay 2: Avoiding path dependence of distributional weights: Lessons from climate change economic assessments. In Essay 2, I explore shortcomings in income weighting in evaluation of climate change policy. In short, in previous versions of two of the most important existing models, regional economic growth is double counted. The proposed alternative approaches yield about 20–40% higher values of SCCO2 than the old approach. Essay 3: Does uncertainty make cost-benefit analyses pointless? In Essay 3, the aim is to investigate to what extent CBA improves the selection decision of projects when uncertainties are taken into account, using a simulation-based approach on real data of infrastructure investments. The results indicate that, in line with previous literature, CBA is a rather robust tool and considerably increases the quality of decision making compared with a random selection mechanism, even when high levels of uncertainty are considered. Essay 4: Household Production and the Elasticity of Marginal Utility of Consumption. In Essay 4, I develop a new model to show that omission of household production in a previous model leads to bias when the elasticity of marginal utility of consumption, EMUC, is estimated. I further offer new, unbiased estimates based on current evidence of the included parameters, suggesting a lower bound of EMUC at about 0.9.

Kleine Moleküle wie Treibhausgase, aber auch Distickstoff und Disauerstoff stehen im Fokus der chemischen Forschung. Solche Moleküle sind durch ihr Vorkommen in der Atmosphäre ubiquitär vorhanden, preiswert und könnten als Synthesebausteine für die Darstellung von komplexeren Molekülen verwendet werden. In dieser Arbeit wurde die Reaktion koordinativ ungesättigter Diketiminato-Nickelkomplexe ([LNi] Komplexe) mit kleinen Molekülen untersucht. Zunächst wurden die Mechanismen der N2-Aktivierung durch reduzierte [LtBuNiI]- und [LMe6NiI] Komplexe miteinander verglichen. Dabei konnte das distickstoffaktivierende Schlüsselintermediat identifiziert und strukturell charakterisiert werden. Weiter wurden die N2-Komplexe [(LtBuNiI)( 1 1 N2)] bzw. K2[(LtBuNiI)( 1 1 N2)], die Vorläufer für [LNiI]- und [LNi0]– Komplexfragmente darstellen, hinsichtlich ihrer Potentials zur Aktivierung der reaktionsträgen Treibhausgase SF6 und NF3 untersucht. Über Reaktionen von Übergangsmetallkomplexen mit NF3 war bis dahin noch nicht berichtet worden; zur Umsetzung von SF6 existierten wenige Publikationen, in denen aber sehr viele mechanistische Fragen offengeblieben sind. Die Mechanismen der SF6- und NF3-Aktivierung wurden durch Kombination einer Vielzahl von ex- und in situ Analysen beleuchtet. Im Falle der SF6 Aktivierung gelang es zudem, ein Nickel(I)-Intermediat zu isolieren. Ein Produkt beider Systeme war der Fluorido-Nickel(II)-Komplex [LtBuNiIIF], dessen Reaktionsverhalten ebenfalls studiert wurde. Doch nicht nur Komplexe mit Nickelatomen in niedrigen Oxidationsstufen erwiesen sich für die Aktivierung kleiner Moleküle geeignet, sondern auch kationische [LtBuNiII(D)]+-Komplexe. Diese Nickel(II)-Komplexe reagierten mit fluorierten Molekülen, N2O sowie O2, was bemerkenswert ist, da Nickel(II)-Komplexe üblicherweise inert gegenüber O2 sind. Im Zuge der O2-Studien wurde ein metastabiler Oranoperoxidkomplex isoliert und strukturell charakterisiert, was beispiellos in der Literatur ist. / Current research focuses on the activation of small molecules like greenhouse gases, thermodynamically stable molecules like N2 and kinetically stabilized molecules like O2, which are all abundant in the atmosphere. Thus, it appears to be alluring to use them as cheap and readily available building blocks for the synthesis of value-added compounds. This dissertation deals with the reaction of low-coordinate diketiminate nickel complexes [LNi] and such small molecules. Initially, the mechanisms of the dinitrogen activation by reduced [LtBuNiI] and [LMe6NiI] complexes were studied. As a result, the key intermediate [(LtBuNiI)x(3 Br)xKx] (x > 1) was identified and structurally characterized. Subsequently, the nickel complexes [(LtBuNiI)( 1 1 N2)] and K2[(LtBuNiI)( 1 1 N2)], which represent sources for [LtBuNiI] and [LtBuNi0]– moieties, were applied to the activation of the inert, but very efficient greenhouse gases SF6 and NF3. Prior to these investigations, no transition metal complex had been reported to react with NF3. Publications dealing with the conversion of SF6 had been scarce, too, while at same time, the mechanisms involving its activation had been speculative. The mechanisms of the NF3 and SF6 activation reactions were deduced combining numerous ex-situ and in situ analytical methods. In case of the SF6 activation, even an intermediate could be isolated. In both systems, the nickel fluoride complex [LtBuNiIIF] was formed and its reaction behaviour was also studied. Furthermore, not only [LtBuNiI]- and [LtBuNi0]– moieties proved to be reactive towards small molecules, but also cationic [LtBuNiII(D)]+ complexes, which were specifically developed for this purpose. The reactions of [LtBuNiII(D)]+ complexes with fluorinated molecules (e. g. PhF, NF3), O2 and N2O were studied. In course of the O2 activation, a metastable organoperoxide complex was isolated and structurally characterized, which is unparalleled in the literature.