Substituent Effects in π-Hole Regium Bonding Interactions Between Au(p-X-Py)2 Complexes and Lewis Bases: An ab initio Study

Long range substituent effects in regium bonding interactions involving Au(I) linear complexes are investigated for the first time. The Au(I) atom is coordinated to two para-substituted pyridine ligands. The interaction energy (RI-MP2/def2-TZVP level of theory) of the π-hole regium bonding assemblies is affected by the pyridine substitution. The Hammett's plot representations for several sets of Lewis bases have been carried out and, in all cases, good regression plots have been obtained (interaction energies vs. Hammett's σ parameter). The Bader's theory of “atoms-in-molecules” has been used to evidence that the electron density computed at the bond critical point that connects the Au-atom to the electron donor can be used as a measure of bond order in regium bonding. Several X-ray structures retrieved from the Cambridge Structural Database (CSD) provide experimental support to the existence of π-hole regium bonding in [Au(Py)₂]⁺ derivatives.     

On the ordinal equivalence of the Johnston, Banzhaf and Shapley power indices

In this paper, we characterize the games in which Johnston, Shapley-Shubik and Penrose-Banzhaf-Coleman indices are ordinally equivalent, meaning that they rank players in the same way. We prove that these three indices are ordinally equivalent in semicomplete simple games, which is a newly defined class that contains complete games and includes most of the real-world examples of binary voting systems. This result constitutes a twofold extension of Diffo Lambo and Moulen’s result (Diffo Lambo and Moulen, 2002) in the sense that ordinal equivalence emerges for three power indices (not just for the Shapley-Shubik and Penrose-Banzhaf-Coleman indices), and it holds for a class of games strictly larger than the class of complete games.     

Function extended spaces

Extended function spaces defined over the real field are defined as vector spaces made by the Cartesian product of a real Euclidian space and a real function space. This construct is related to the Holographic Electronic Density Theorem and to the stereographic projection of quantum chemically related and well behaved functions in general. It permits to establish the basis for the Holographic General Function Theorem.     

Intrinsic vanishing of energy and momenta in a universe

We present a new approach to the question of properly defining energy and momenta for non asymptotically Minkowskian spaces in General Relativity, in the case where these energy and momenta are conserved. In order to do this, we first prove that there always exist some special Gauss coordinates for which the conserved linear and angular 3-momenta intrinsically vanish. This allows us to consider the case of creatable universes (the universes whose proper 4-momenta vanish) in a consistent way, which is the main interest of the paper. When applied to the Friedmann-Lema?tre-Robertson-Walker case, perturbed or not, our formalism leads to previous results, according to most literature on the subject. Some future work that should be done is mentioned.     

Studies on the Amination of Aryl Chlorides with a Monoligated Palladium Catalyst: Kinetic Evidence for a Cooperative Mechanism

Combined spectroscopic, crystallographic, and kinetic studies of the mechanism of aromatic amination with the efficient dinuclear Pd precatalyst [Pd₂Cl(μ‐Cl)PtBu₂(Bph‐Me)] (Bph‐Me=2′‐methyl‐[1,1′‐biphenyl]‐2‐yl) have revealed overlapping, yet cooperative, mechanistic scenarios, the relative weights of which are strongly influenced by the products formed as the reaction proceeds. The stability and evolution of the precatalyst in solution has been studied and several metalation pathways that point to a single monoligated intermediate have been identified. Our work sheds light on the nature of the catalytic species involved in the process and on the structure of the corresponding catalytic network.     

Long‐lived states in an intrinsically disordered protein domain

Long‐lived states (LLS) are relaxation‐favored spin population distributions of J‐coupled magnetic nuclei. LLS were measured, along with classical ¹H and ¹⁵N relaxation rate constants, in amino acids of the N‐terminal Unique domain of the c‐Src kinase, which is disordered in vitro under physiological conditions. The relaxation rates of LLS can probe motions and interactions in biomolecules. LLS of the aliphatic protons of glycines, with lifetimes approximately four times longer than their spin–lattice relaxation times, are reported for the first time in an intrinsically disordered protein domain. LLS relaxation experiments were integrated with 2D spectroscopy methods, further adapting them for studies on proteins. Copyright © 2013 John Wiley & Sons, Ltd.     

Mathematical aspects of the LCAO MO first order density function (5): centroid shifting of MO shape functions basis set, properties and applications

In MO SCF theory and related computational levels, the first order density function (DF) can be considered as a linear combination of the MO shape functions (ShF) set. This work studies the possibility of constructing a centroid function from the ShF set elements using it to perform a ShF set origin shift, while permitting the DF decomposition in two well defined function terms. The properties and consequences of such a simple operation are analyzed in deep.     

Overriding subsuming rules

This paper is concerned with intelligent agents that are able to perform nonmonotonic reasoning, not only with, but also about general rules with exceptions. More precisely, the focus is on enriching a knowledge base Γ with a general rule that is subsumed by other rules already there. Such a problem is important because evolving knowledge needs not follow logic as it is well-known from e.g. the belief revision paradigm. However, belief revision is mainly concerned with the case that the extra information logically conflicts with Γ. Otherwise, the extra knowledge is simply doomed to extend Γ with no change altogether. The problem here is different and may require a change in Γ even though no inconsistency arises. The idea is that when a rule is to be added, it might need to override any rule that subsumes it: preemption must take place. A formalism dedicated to reasoning with and about rules with exceptions is introduced. An approach to dealing with preemption over such rules is then developed. Interestingly, it leads us to introduce several implicants concepts for rules that are possibly defeasible.