Formal charge, 33

It will always be true that a covalently bonded hydrogen has no formal charge (formal charge = 0)... 

In an oxidative addition reaction a compound XY adds to a metal complex during which the XY bond is broken and two new bonds are formed, MX and MY. X and Y are reduced, and both will have a minus one charge (formally at least) and hence the formal oxidation state of the metal is raised by two. The co-ordination number of the metal also increases by two. While the electron... 

IV. 3. Compounds with the Negative Charge Formally on a Carbon... 

Figure 6-11. The reaction of 6.16 with BF3 gives the nickel(n) complex of a new macrocyclic ligand. The ligand is dianionic, with the charge formally localised upon the tetrahedral boron atoms.

Clusters 36 and 37 are closely related zwitterions with negative charge formally located at the metal atoms. This is apparent from the lower values for v(CO), and the monohydride form of these compounds is also consistent with this (108b). 

With olefinic monomers the substituent, Y, is often electron donating e.g. —OR, —NR2 —Ar, and therefore capable of stabilizing a positive charge formally residing on the a carbon atom, e.g. 

An intermediate situation between cases (b) and (c) is that of a Stem layer with specific adsorption, for which the general charging formalism is available from sec. II.3.6f. The result is, see [11.3.6.65],... 

Formal positive charge Formal negative charge... 

Enolate The anion of an enol, in which the negative charge formally resides on the oxygen. Enthalpy The energy of a system. 

Assign formal charges. Formal charge is a comparison of the number of electrons an atom owns in the Lewis structure with the number it would have if it were free. The atom is assigned only half of the electrons that it shares in a bond, but all of its unshared electrons. 

These structures are known as resonance structures. The true structure is some weighted average of these three. That is, each N-0 bond is between a single and double bond in length, as is the N-N bond. In order to rank the relative importance of each structure, we need to use formal charges. Formal charge, FC, is an arbitrary property. We define the formal charge on a specific atom by... 

Electronics/charge (formal charge, partial atom charges, dipole moment and vectors, HOMO and LUMO energy, F and R snbstitnent constants, etc.)... 

Formal charges Formal charges are assigned by apportioning bonding electrons equally between the two atoms involved. They can be useful to rationalize apparent anomalies in bonding, and to assess the likely stability of a proposed valence structure. 

The concepts of hardness, softness, and of frontier orbitals, with which latter the Fukui function is closely coimected, have been severely criticized [103, 120]. It is also true that in some cases the results predicted using these methods can also be understood in terms of more traditional chemical concepts. Thus, in the alkyne-HNC reaction, resonance theory leads one to suspect that the zwitterion A, with the positive charge formally on the more substituted carbon, will be favored over B. Indeed, AMI, HF/6-31G and pBP/DN DFT calculations all show A to be of lower energy than B. 

Molecule Oxidation Number Calculated Charge Formal Charge... 

A Lewis structure is not considered complete unless the formal charges are indicated (no "0" is used). The best Lewis structure is the one (or ones if a resonance hybrid) with the lowest formal charges. Formal charges greater than 1 are never found in good Lewis structures. 

MM treats atoms as hard spheres joined by elastic bonds that behave like harmonic oscillators. In addition, electrostatic charges (formal and/or partial) may be included in the calculation along with other, long range interactions such as van der Waals forces. The total energy of the system may be broken down into the following components ... 

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