M-F interactions and heterobimetallics: furthering the understanding of heterobimetallic stabilization.

Heterobimetallic complexes containing alkali, alkaline-earth, and divalent europium metals utilizing the perfluoro-tert-butoxide (PFTB) ligand following the general formula, [AM(PFTB)3(co-ligand)x] (A=Na, K; M=Mg, Sr, Ba, Eu; co-ligand=THF, toluene), have been isolated. These compounds sublime at low temperatures with low residual weight indicating their potential as metal-organic chemical-vapor deposition (MOCVD) precursors. The complexes have unique molecular architectures that are strongly influenced by M-F interactions, as was verified in the solid state by using X-ray crystallography.

Terahertz spectroscopy and solid-state density functional theory simulations of the improvised explosive oxidizers potassium nitrate and ammonium nitrate.

Terahertz spectroscopy provides a noninvasive and nondestructive method for detecting and identifying concealed explosives. In this work, the room-temperature and cryogenic terahertz spectra of two common improvised explosive oxidizers, namely, potassium nitrate (KN) and ammonium nitrate (AN), are presented, along with detailed solid-state density functional theory (DFT) analyses of the crystalline structures and spectral features. At both 294 and 78 K, KN exhibits two terahertz absorption features below 100 cm(-1) that have been assigned through DFT simulations to arise from hindered nitrate rotations in the KN-II crystalline polymorph.

Identification and quantification of polymorphism in the pharmaceutical compound diclofenac acid by terahertz spectroscopy and solid-state density functional theory.

Polymorph detection and quantification in crystalline materials is a principle interest of the pharmaceutical industry. Terahertz (THz) spectroscopy can be used for such analytical applications since this technique is sensitive to the intermolecular interactions of molecules in the solid state. Understanding the fundamental nature of the lattice vibrational motions leading to absorptions in THz spectra is challenging, but may be achieved through computational approaches.

Application of London-type dispersion corrections to the solid-state density functional theory simulation of the terahertz spectra of crystalline pharmaceuticals.

The effects of applying an empirical dispersion correction to solid-state density functional theory methods were evaluated in the simulation of the crystal structure and low-frequency (10 to 90 cm(-1)) terahertz spectrum of the non-steroidal anti-inflammatory drug, naproxen. The naproxen molecular crystal is bound largely by weak London force interactions, as well as by more prominent interactions such as hydrogen bonding, and thus serves as a good model for the assessment of the pair-wise dispersion correction term in systems influenced by intermolecular interactions of various strengths. Modifications to the dispersion parameters were tested in both fully optimized unit cell dimensions and those determined by X-ray crystallography, with subsequent simulations of the THz spectrum being performed.

Understanding the terahertz spectra of crystalline pharmaceuticals: terahertz spectroscopy and solid-state density functional theory study of (S)-(+)-ibuprofen and (RS)-ibuprofen.

The potential applications of terahertz (THz) spectroscopy in the analysis of pharmaceutical products in their crystalline state have prompted the need for a more thorough understanding of the fundamental vibrational motions contributing to the THz spectra. The detection of variations in crystal structure and the reliable assignment of observed THz absorption features can be aided by the use of solid-state density functional theory (DFT). In this study, solid-state DFT with periodic boundary conditions was used to simulate the crystalline structure and assign the experimental THz spectra (10-90 cm(-1)) of the enantiomerically pure and racemic forms of the common pharmaceutical compound ibuprofen.

Investigating the anharmonicity of lattice vibrations in water-containing molecular crystals through the terahertz spectroscopy of L-serine monohydrate.

The influence of cocrystallized H(2)O molecules on the terahertz (THz) spectra and corresponding computational treatment of hydrated molecular crystals was investigated in the study of protonated and deuterium-substituted l-serine.H(2)O. The THz spectra of both solids have been measured in the range of 10 to 90 cm(-1), with simulations of the crystalline structure and THz vibrational modes performed using solid-state density functional theory.

Highly volatile alkaline earth metal fluoroalkoxides.

The synthetic strategies, structural comparison, and thermal gravimetric analyses for a novel family of alkaline earth metal perfluoro-tert-butoxides (PFTB) are presented. The isolated complexes follow the general formula, [Ae(PFTB)(2)(d)(x)]; (1a, Ae = Mg, d = THF, x = 2; 1b, Ae = Ca, d = THF, x = 4; 1c, Ae = Sr, d = THF, x = 4; 1d, Ae = Ba, d = THF, x = 4; 2a, Ae = Mg, d = DME, x = 1; 2b, Ae = Ca, d = DME, x = 2; 2c, Ae = Sr, d = DME, x = 2; 2d, Ae = Ba, d = DME, x = 3; 3a, Ae = Mg, d = diglyme, x = 1; 3b, Ae = Ca, d = diglyme, x = 2; 3c, Ae = Sr, d = diglyme, x = 2; 3d, Ae = Ba, d = diglyme, x = 2; THF = tetrahydrofuran, DME = 1,2-dimethoxyethane) where the crystallographically characterized compounds display either a cis or trans conformations in octahedral or pseudo-octahedral environments. Alkane elimination (Mg), direct metalation via ammonia activation (Ca, Sr, Ba), and transamination (Ca, Sr, Ba) methods yielded the target compounds in moderate to good yields.

Synthesis and stabilization-advances in organoalkaline earth metal chemistry.

The last decade has seen an impressive growth in alkaline earth metal chemistry, with applications ranging from synthetic organic and polymer chemistry to materials science. As a consequence, alkaline earth metal chemistry has made a leap from obscurity into the spotlight of modern organometallic chemistry. Much of this rapid development was made possible by the establishment of novel synthetic procedures that allowed facile access to the target compounds, as many conventional synthetic routes posed and continue to pose significant limitations.

Synthesis of novel 2H,5H-Dihydrofuran-3-yl Ketones via ISNC reactions.

Unique 1-[2H,5H-dihydrofur-3-yl]ketones have been synthesized from propargylic nitroethers via intramolecular cycloadditions involving silyl nitronates. Various substituent groups were placed on the 2 and 5 positions of the dihydrofuran rings. We examined the scope of the long-range coupling in proton NMR of the oxo-dihydrofuran products.