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N -Butyl-2,3-bis(dicyclohexylamino)cyclopropenimine ( 1 ) crystallizes from benzene and hexanes in the presence of HCl as a monobenzene solvate of the hydrochloride salt, [ 1 H]Cl·C 6 H 6 or C 31 H 54 N 3 + ·Cl − ·C 6 H 6 , in the P 2 1 / n space group. The protonation of 1 results in the generation of an aromatic structure based upon the delocalization of the cyclopropene double bond around the cyclopropene ring, giving three intermediate C—C bond lengths of ∼1.41 Å, and the delocalization of the imine-type C—N double bond, giving three intermediate C—N bond lengths of ∼1.32 Å. Ion–ion and ion–benzene packing interactions are described and illustrated. 

A series of Ca–Mn clusters with the ligand 2-pyridinemethoxide (Py-CH 2 O) have been prepared with varying degrees of topological similarity to the biological oxygen-evolving complex. These clusters activate water as a substrate in the oxidative degradation of propylene carbonate, with activity correlated with topological similarity to the OEC, lowering the onset potential of the oxidation by as much as 700 mV. 

The role of geometric frustration of water molecules in the rate of water oxidation in the nanoconfined interlayer of manganese-oxide layered materials (birnessite, buserite) is examined in a well-controlled experiment. Calcium buserite is prepared, and used in a split-batch synthetic protocol to prepare calcium birnessite, sodium buserite, and sodium birnessite, and partially dehydrated sodium birnessite. Thus, four samples are prepared in which features effecting catalytic efficiency (defect density, average manganese oxidation state) are controlled, and the main difference is the degree of hydration of the interlayer (two layers of water in buserites vs. one layer of water in birnessite). Molecular dynamics simulations predict birnessite samples to exhibit geometric water frustration, which facilitates redox catalysis by lowering the Marcus reorganization energy of electron transfer, while buserite samples exhibit traditional intermolecular hydrogen bonding among the two-layer aqeuous region, leading to slower catalytic behavior akin to redox reactions in bulk water. Water oxdiation activity is investigated using chemical and electrochemical techniques, demonstrating and quantifying the role of water frustration in enhancing catalysis. Calculation and experiment demonstrate dehydrated sodium birnessite to be most effective, and calcium buserite the least effective, with a difference in electrocatlytic overpotential of ∼750 mV and a ∼20-fold difference in turnover number. 

Cyanuric triazide reacts with several transition metal precursors, extruding one equivalent of N 2 and reducing the putative diazidotriazeneylnitrene species by two electrons, which rearranges to N -(1′ H -[1,5′-bitetrazol]-5-yl)methanediiminate (biTzI 2− ) dianionic ligand, which ligates the metal and dimerizes, and is isolated from pyridine as [M(biTzI)] 2 Py 6 (M = Mn, Fe, Zn, Cu, Ni). Reagent scope, product analysis, and quantum chemical calculations were combined to elucidate the mechanism of formation as a two-electron reduction preceding ligand rearrangement. 

Of interest in understanding electronic structure, bulk physical properties, enthalpies of phase changes, dipole moments, and numerous other properties of molecules, is the determination of realistic partial atomic charges on atoms. Atoms may take on partial positive or negative charges due to polar covalent bonds, coordinate covalent bonds, or due to formal charges imposed by Lewis structure constraints. Traditional crystallographic refinement treats each atom as a neutral, spherical atom however. We present a ongoing developments of a mode of crystallographic model refinement that permits refinement of electron density at individual atoms in order to arrive at partial atomic charges of atoms in a crystallographic model. Comparison to calculated partial charges (CHELPG, NBO, Mulliken) from quantum calculations (DFT, MP2) in both the gas phase and crystalline state will be presented. 

Modern crystallographic refinement methods treat each atom in a molecule as neutral with spherical electron density. Atoms, however, exhibit partial atomic charges arising from intramolecular forces via bonding. These partial charges are crucial for understanding electronic structure and bulk physical properties of molecules. Typically the polarity and polarizability of molecules are calculated using IR and Raman spectroscopy, respectively. While these techniques can be used on small molecules, fine elucidation of partial charges on individual atoms is still unrealized. Here we present crystallographic refinement developments that allow us to refine electron density around individual atoms to experimentally calculate partial atomic charges. Comparison between these experimentally calculated charges to theoretical quantum calculated charges will also be presented. 

Derivation of partial charges in small and large scale molecular systems is important for modeling of various experimental and theoretical properties like dipole moments, auto-correlation functions, charge disparity, understanding of dispersion, benchmark of classical MD simulations and electrostatic potential energy surface mapping. A correspondence between theoretical calculations (based on single/small number of molecules) is usually established with macroscopic IR/Raman spectra or dipole moment measurements. Such comparisons are indirect and lack a fine mapping of electrostatic potential from theory to experiment. In a new approach developed as the experimental part of this work, partial charges are calculated from crystallographic model refinement. The experimental method exhibits a satisfactory correspondence with partial charges obtained using quantum chemistry calculations. Particularly, gas phase partial charges from CHELPG method and condensed phase Lowdin charges correlate well and validate this experimental method. 

The Database of Educational Crystallographic Online Resources (DECOR) is the worlds first repository for educational resources for the teaching of crystallography and diffraction. The site, available at decor.cst.temple.edu, permits the sharing and downloading of educational resources such as practice problems, visual aids, animations, and more. The site is currently organized into three basic resource layouts: 1) Resources by Type, where visitors can browse for homework problems, presentations slides, or animations across topics. 2) Resources by Topic, where visitors can look for resources relating to particular subject matter such as the reciprocal lattice, scattering, or symmetry. 3) Links, which sends visitors to other sites that provide convenient resources for crystallographic education. The purpose of the poster is to make attendees aware of this teaching resource, and to present the current state of the site, and plans to upgrade and enhance it in the near future.