Inorganic aromatic compounds aromaticity

Inorganic lead compounds such as PbO, Pb02, Pb304, PbS, lead molybdate and lead perchlorate 2) Lead salts of organic adds such as 2,4-dihydroxy benzoic add, salicylic add, acetyl salicylic add and methoxy propionic add i) Effective with propellants of cal. val. less than 900 cal. g 1 ii) Lead salts of aromatic adds are effective with propellants of higher cal. val. [237]. 

Three methods for the preparation of aromatic arsonic adds are de- scribed in this review. By far the most widely applicable of these is the Bart reaction, which involves the interaction of a diazonium salt with an inorganic arsenic compound. In the original Bart process 1 and most of its modifications an alkali arsenite is used, as shown in the following equation. 

The yellow to orange compounds 804(118207)2, 864(84 013)2, and 8e4(8b2Fii)2 have been prepared. Crystallographic studies on 804(118207)2 have shown that the cation 8c4 + has square-planar D h) geometry. The structure can be described by valence bond theory in terms of four resonance structures equivalent to (la), or by simple molecular orbital theory in which three of the four n molecular orbitals are filled. " The 8e4 + ions are examples of six-jr-electron systems, and they are thus examples of inorganic aromatic compounds (lb). 

There are, however, also a few inorganic diazo compounds in which X has 18 or more atoms and, in addition, the members of this group have a stability and reactivity comparable to those of aromatic diazo compounds. These are the mono- and bis(diazo)boranes, which were discovered by the group of Muetterties in their work on cluster-type boron hydrides (Knoth et al., 1964). 

In this chapter, we focus on aromaticity and antiaromaticity in inorganic compounds only. It means that the chemical species, which will be discussed, do not contain carbon atoms in their cyclic structures. There are a few review articles [17-25], which discuss different aspects of aromaticity and antiaromaticity in inorganic chemistry. Before we go further, we would like to outline the structure of this chapter. First, we describe criteria that are commonly used for probing aromaticity. Second, we consider inorganic aromatic molecules, which we loosely call conventional aromatic molecules. These molecules are simply isoelectronic species to one of the organic aromatic molecule. Third, we focus on what we loosely call unconventional aromatic molecules composed of main group atoms and transition-metal atoms. Finally, we conclude the chapter with a summary and short outlook. 

The nucleating system for poly(p-phenylene sulfide) includes a combination of an inorganic crystalline compound and an aromatic amide oligomer. Because of the improved crystallization rate, the thermoplastic composition can be molded at lower temperatures to still achieve the same degree of crystallization. The inorgartic compound is boron nitride. Boron nitride used alone has also been proposed for PPS. ... 

One other approach that was considered was ranking chemicals by groups according to their physical and chemical properties. A number of properties were selected, for example, LD50, bioaccumulation, and persistence as the main criteria for toxicity to the environment and humans. Substances were then classified according to the range they fell within (Ministers Advisory Panel, 1995). This approach was used for the Canadian Environmental Protection Act (CEPA) assessments. For example, polychlorinated dibenzodioxins, polycyclic aromatic hydrocarbons, inorganic cadmium compounds, benzidine, trichloroethylene, and a host of others were concluded to be toxic. Others, such as chlorobenzene, toluenes, xylenes, and dibutyl pthalate, were concluded to be nontoxic. Others, such as aniline, styrene, crankcase oils, and pentachlorobenzene, do not have sufficient information for classification. 

De Proft and co-workers [33] determined the aromaticity of a series of inorganic monocyclic compounds, including the 84 and Se planar clusters. These authors obtained maps of the induced current density with the CTOCD-DZ/6-311G ... 

Organic and inorganic chlorine compounds can have a deleterious effect on equipment and reactions in processes involving aromatic hydrocarbons. 

Recent trends and developments in theoretical methods are outlined in the following section. The aromaticity of sulphur heterocycles is considered separately. The main part of the review concerns theoretical studies of different classes of compounds and these are grouped according to chemical structure. In this way this Report follows previous reviews by Zahradnik (to 1964) and by Park nyi (1965—1969). Another survey by the Reporter has covered the quantum chemistry of organic and inorganic sulphur compounds up to 1970. Some aspects of structure and bonding in organosulphur compounds have been considered more recently by Clark. ... 

In addition to inorganic radicals, which profoundly modify the properties of a paraflSn hydrocarbon residue, there is a whole series of organic groupings which are distinguished by exceptional reactivity, for example, the ethylene and acetylene groupings, and the phenyl and naphthyl radicals. Thus the characterisation of unsaturated hydrocarbons and their derivatives, e.g., the aromatic compounds, becomes possible. 

Physical Properties. Furfural [98-01-1] (2-furancarboxaldehyde), when freshly distilled, is a colorless Hquid with a pungent, aromatic odor reminiscent of almonds. It darkens appreciably on exposure to air or on extended storage. Furfural is miscible with most of the common organic solvents, but only slightly miscible with saturated aHphatic hydrocarbons. Inorganic compounds, generally, are quite insoluble in furfural. 

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