Electronegativity. II. Bond and Orbital Electronegativities

Self Cite

The 35CI nuclear quadrupole resonance (n.q.r.) frequencies at 77 "K of twenty-two chloroformates, twenty-eight acid chlorides, two thiocarbonyl molecules, and five carbamyl chlorides are reported. Introductionchlorine by a saturated linkage. The frequency The planarity (1, 2) of the -X-COCI unit suggests n-bonding, and the difference in .nbonding when X is R, 0 , S, or N could be measured by comparing the 35C1 n.q.r. in equivalent molecules. Unfortunately, no resonances were detected in -SCOCI molecules nor in -NCSCl molecules. Frequencies were obtained for thirteen pairs of molecules, RCOCl and ROCOCI, and the frequency variation within each series was small. The frequency variation is qualitatively discussed.

Section: The Carbamyl Moleculessupporting

confidence: 56%

Section: The Chloroformate Moleculesmentioning

confidence: 99%

³⁵Cl Nuclear Quadrupole Resonance of Alkyl Chloroformates, Alkyl Acid Chlorides, and Carbamyl Chlorides

Hart¹,

Whitehead²

1971

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“…As indicated earlier, electronegativities are known to depend on the nature of the chemical bond and the bonding orbitals for which they are evaluated (32)(33)(34)(35). I t appears ( …”

Section: Evaluation Ofmentioning

confidence: 97%

Free-energy Relationships in Coordination Chemistry. III. A Comprehensive Index to Complex Stability

Nieboer¹,

McBryde²

1973

101

Dans le but de relier les constantes de stabilitt mttal-complexe B certaine propriCtC des ions rn6talliques, on a dCveloppC un indice numkrique de corrClation Q posskdant les caractCristiques suivantes: ( i ) Q est un parametre double engageant la charge ionique et I'electronCgativitC. I1 peut avoir des valeurs diffkrentes pour un mCtal particulier selon le type de ligand avec lequel les complexes se foment. [ Efforts to relate metal-complex stability constants to some property of the metal ions involved have led to the development of a correlating numerical index Q with the following characteristics: (i) Q is a two parameter quantity involving ionic charge and electronegativity, which may assume different values for a particular metal according to the type of ligand with which complexes are formed; (ii) linear relationships are obtained for plots of log KML 1's. Q for various metals and more than thirty ligands. The effect of the thermodynamic and structural properties of ligands and metal complexes on the slope and intercept in this correlation is discussed. Two new indices to class b behavior are introduced, one for metal ions and one for ligands. The index Q is shown to be related to other published indices of ionic or covalent, class a or class b, behavior of metals and ligands; the alternative ways of assigning Q may be regarded a s reflecting the varying degrees of ionic or covalent character in the complexes of a given metal. IntroductionThe classification of donors and acceptors in inorganic reactions has provided a useful framework for the rationalization of metalcomplex formation in solution. The original division of acceptors (metal ions) by Ahrland, Chatt, and Davies (1) into class a and class b was based on complex stability in solution as measured by equilibrium constants. These ideas were then extended to the ligand donor atoms: class a donors (e.g., N, 0, F) are preferred by class a acceptors, and class b donors (e.g., P, S, C1) by class b acceptors. More recently Ahrland (2-5) has made the generalization that class a reactions in aqueous medium tend to be entropy stabilized, while class b interactions tend to be enthalpy controlled (exothermic). This thermodynamic criterion is useful, but cannot be used in a clear-cut diagnostic test for any individual reaction (see below).

“…(i) The one center, two electron repulsion integrals y,, (1 1.134 eV) were estimated from the relation Yss = Is -As where Is and A, are the sp2 valence state ionization energy (1 1.16 eV) (8) and electron affinity, respectively, of the carbon atom.…”

Section: Methods and Parametersmentioning

confidence: 99%

SCF MO Study Of Benzo[d]aceheptylene

Dasgupta¹,

Dasgupta²

1975