Reaction of LSi-SiL (1) (L = PhC(NtBu)(2)) with diphenyl alkyne gave the first example of a room temperature stable 1,4-disilabenzene. The compound was characterized by means of single crystal X-ray diffraction studies. NICS (nucleus independent chemical shift) calculations showed that the compound has some aromatic character.

A series of monocyclic planar inorganic compounds have been optimized at the B3LYP/6-311+G* level. GIAO-B3LYP nucleus-independent chemical shifts (NICS) profiles calculated in the perpendicular direction of each ring show that the series of analyzed compounds can be classified in three groups according to their aromatic, non-aromatic or antiaromatic character. Our results suggest exercising cau...

Standard ab initio and density functional calculations are carried out to determine the structure, stability, and reactivity of B(12)N(12) clusters with hydrogen doping. To lend additional support, conceptual DFT-based reactivity descriptors and the associated electronic structure principles are also used. Related cage aromaticity of this B(12)N(12) and nH(2)@B(12)N(12) are analyzed through the...

The most refined nucleus-independent chemical shift index (NICS(0)(πzz)) and the extra cyclic resonance energies (ECREs), based on the block localized wave function (BLW) method, show that the aromaticity of all azines is like that of benzene. The same is true for aza-naphthalenes relative to naphthalene. The lower relative energies of isomers with vicinal N's are due to the weakness of NN bond...

The effect of counterions on the bonding, stability and aromaticity of trigonal dianion metal clusters has been analyzed through the behavior of various conceptual density functional theory based reactivity descriptors and the nucleus independent chemical shift calculated at different levels of theory, comprising one-determinant approaches and beyond (QCISD, CASSCF(8,8) and NEVPT2), for a prope...

Twelve bis(benzazole) structures with potential ligand character were investigated by means of computational chemistry. Global and local reactivity descriptors within DFT (Density Functional Theory) theory (Fukui functions, chemical potential, hardness, electrophilicity index) have been computed at B3LYP/6-31G(d,p) level of theory. NICS(0) (Nucleus Independent Chemical Shift) index computations...

Analysis of the molecular orbitals and the nucleus independent chemical shift showed that the D(4h) and D(6h) symmetry Hg(4)(2+) and Hg(6)(2+) rings are aromatic. However, accurate quantum chemical methods indicated that the linear forms are more than 100 kJ mol(-1) lower in energy. This surprising case, where the non-aromatic species are considerably more stable than the aromatic rings, was ex...

tacrine (9-amino-1,2,3,4-tetrahydroacridine) as a reversible inhibitor of acetylcholinesterase (ache),was the first drug for the symptomatic treatment of alzheimer’s disease (ad). nmr structuredetermination still presents some considerable challenges: the method is limited to systems ofrelatively small molecular mass, data collection times are long, data analysis remains a lengthyprocedure, and...

We report on the construction and application of a new bond-current additivity scheme for polybenzenoid hydrocarbons. The method is based identification smaller substructures contained in system, up to tricyclic subunits. Thus, it enables prediction any cata-condensed unbranched hydrocarbon, using library consisting only four building blocks. predicted bond-currents can then be used generate Nu...