Chemical bonding multiple covalent bonds

Both the long C-C bond distance (1.50 A) and the very short Pt—C distances (2.0 A) indicate the strong interaction between the adsorbed molecule and the three platinum surface atoms. The covalent Pt—C distance would be 2.2 A. The shorter metal-carbon distances indicate multiple metal-carbon bonding that may be carbene or carbyne-like. Compounds with these types of bonds exhibit high reactivity in metathesis and in other addition reactions The carbon-carbon single bond distance indicates that the molecule is stretched as much as possible without breaking of this chemical bond. 

Scheme 1.1 The molecular information system modeling the chemical bond between two basis functions /=(o,b) and its entropy/information descriptors. In Panel b, the corresponding nonbonding (deterministic) channel due to the lone-pair hybrid 6° is shown. For the molecular input p = (P, Q), the orbital channel of Panel a gives the bond entropy-covalency represented by the binary entropy function H[P). For the promolecular input p° = (1/2,1/2), when both basis functions contribute a single electron each to form the chemical bond, one thus predicts H[p°] = 1 and the bond information ionicity / = 1 — H(P). Hence, these two bond components give rise to the conserved (P-independent) value of the single overall bond multiplicity N = I + S = 1.

The variable-input norm description of the decoupled chemical bonds gives the full agreement with the chemical intuition, of r bonds in XH with changing covalent/ionic composition in accordance with the actual MO polarization and the adopted basis set representation. The more the probability parameter P deviates from the symmetrical bond (maximum covalency) value P = 1/2, due to the electronegativity difference between the central atom and hydrogen, the lower is the covalency (the higher ionicity) of this localized, diatomic bond. Therefore, in this IT description the total bond multiplicity Af = r bits is conserved for changing proportions between the overall covalency and ionicity of all chemical bonds in the system under consideration. 

The Next Important Elements to Life Occur in Period 3 P and S are the smallest elements capable of multiple covalent bonds to C, O and N, and which also have available d-shells. The d-shells allow additional transition states and reaction mechanisms. P and S are particularly important in the capture, storage, and distribution of chemical energy. 

QTAIM provides a definitive answer to the question of whether two atoms are bonded or not even in ambiguous cases [87, 88] and, as a consequence, the molecular graph, i.e., the chemical structure, is readily defined by this theory. Two atoms are bonded if their nuclei are linked in space by a line of maximal electron density termed the bond path [89, 90] (see Fig. 1). A single bond path links the nuclei of chemically bonded atoms irrespective of the mode of the bonding covalent (single or multiple), hydrogen, van der Waals, ionic, metallic, etc. The properties of the eleetron density determined at the point of lowest density along the bond path, where... 

Chemistry has a knack of using terms such as valency, electronegativity and bonding which have a multiplicity of meanings. In its broadest sense, valency has been used to describe the ability of elements to combine with others. Russell s book provides a thorough analysis of the history of valency [15]. A chemical bond is more precisely defined as the force which holds two chemical entities together, but the definition encompasses a duality which at its extremes is based on either electrostatic (ionic) or covalent bonding and in between a variable amount of covalent and ionic character. 

FIGURE 8.15 Conservation of the overall entropic bond multiplicity J °(P) = 1 bit in the 2-AO model of the chemical bond, combining the conditional entropy (average noise, bond covalency) S P) = H(P) and the mutual information (information capacity, bond ionicity) P(P) = 1 - H P). In MO theory, the direct bond order of Wiberg is represented by the (broken line) parabola M yP) = 4P(1 -P) = 4PQ. 

The Wiberg index has thus been recovered as the overall IT descriptor of the chemical bond in the 2-AO model, with its covalent (Sab) and ionic (/ ) contributions being established at the same time. It follows from Figure 8.17 that these IT covalency/ionicity components compete with one another while conserving the Wiberg bond order as the overall information measure of chemical bond multiplicity... 

To define a macromolecule, it is necessary first to consider the basic definition of a molecule. A molecule is a group of atoms connected by covalent chemical bonds. The chemical structure of the molecule is defined by the specific connectivities between the atoms. Some atoms can covalently bond to more than one other atom. The study of macromolecules explores the rich variety of chemical structures that can be created by assemblies of atoms that display multiple valence. 

De Divina Proportione right in the middle of a framework of covalent chemical bonds used as molecular sieve Only Science I think is able to produce such coimections between different times and different length-scales, a short-circuit that eventually generates new Science surely, readers will find a source of inspiration in the multiple sections of this book dealing with crystallography, quantum mechanics and other topics. 

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