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While most general chemistry textbooks recognize that differences in electronegativity between bonded atoms provide only an indication of bond type, the difference function of electronegativity itself is both inadequate and improper for determining bond type. An alternative algorithm based on the unfunctionalized values of electronegativity for the two bonded atoms in binary compounds of representative elements provides much better discrimination between ionic and covalent bonding. This algorithm not only removes the ambiguity introduced by the difference function, but at the same time provides for the natural inclusion of the third type of interatomic bond--metal-metal bonding. Textbook authors should indicate that the absolute values of electronegativity, not their differences, are most useful for predicting bond type. Also, the value of electronegativity of the element of higher electronegativity in binary compounds determines whether the compound will be metallic. If a compound is not metallic, the electronegativity of the element of lower electronegativity determines whether the compound will exhibit primarily ionic or covalent character if that element is representative. If the element of lower electronegativity is a transition metal, the bond character is not predictable using electronegativities alone.

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The nickel(IV) complex, bis(2,6-diacetylpyridine dioximato)nickel(IV), Ni(C9N302H9), has been examined by single-crystal X-ray structural techniques. The crystallographic data are: Laue symmetry 4/m; space group, I4Ja;a = b = 7.745 (3) A, c = 30.510 (16) A; dm = 1.59 (2) g/cm3; dx = 1.600 g/cm3 for four monomeric molecules in the unit cell. The 8371 reflections were measured on an automated Picker four-circle diffractometer and gave 702 unique observations for the structural analysis. Full-matrix least-squares analysis including hydrogen atoms gave final discrepancy factors of R = 0.028 and Rw = 0.025, S = 0.93. The crystallographic and molecular symmetry of the molecule is 4 (SJ with the nickel atom coordinated to two 2,6-diacetylpyridine dioximato ligands via the six nitrogen atoms of these ligands. A comparison of these nickelnitrogen distances with those found in nickel(II) complexes suggests a shortening of 0.17 A in the Ni(IV)-N bond. This average difference of 0.17 A for t2g6 and t2g6eg2 with a change in formal oxidation number of 2 can be compared with the 0.18-A difference reported earlier in the t2gseg2 Co(NH3)62+ and t2g6 Co(NH3)63+ complexes with a change in formal oxidation number of 1.

Scales of electronegativity values are used by chemists to describe numerous chemical features such as chemical mechanisms, bond polarity, band gap, atomic hardness, etc. While the many scales provide similar trends, all differ in their predictive quality. Confirmation of the quality of a new scale often uses a previous scale for comparison but does not use independent means to demonstrate the merits of the scale. Utilizing a table of binary compounds of known ionic, covalent, and metallic bonding characters, a means to evaluate electronegativity scales is developed here. By plotting the electronegativity values of the two bonded atoms in binary compounds of a known bonding character, a tripartite separation results that generally divides the three bond types. Using the results of graphs of this sort, the success of bonding separations of 14 different scales of electronegativity has been evaluated on the basis of three quantitative parameters that can provide a measure of the quality of the scales. Three scales, those of Allen, Martynov and Batsanov, and Nagle, have been shown to be superior in their ability to predict the expected separation of bond types. Since this scheme successfully demonstrates the ability to evaluate the quality of electronegativity scales, it can be applied to other scales to establish their effectiveness in predicting bond types in binary compounds and thus the quality of the scales. This scheme is applied to a recently published electronegativity scale to evaluate the ability to determine its quality.

Researchers have formed peptide bonds under a variety of presumed prebiotic conditions. Here it is proposed that these same conditions would have also formed amide bonds between fatty acids and amino acids, producing phosphate-free amphipathic lipoamino acids and lipopeptides. These compounds are known to form vesicles and are ubiquitous in living organisms. They could represent molecules that provided protection by membranes as well as possibilities for proto-life metabolism . It is here demonstrated that when a fatty acid is heated with various amino acids, optimally in the presence of suitable salts or minerals, lipoamino acids are formed. Magnesium and potassium carbonates as well as iron (II) sulfide are found to be particularly useful in these reactions. In this manner N-lauroylglycine, N-lauroylalanine, N-stearoylalanine and several other lipoamino acids have been synthesized. Similarly, when glycylglycine was heated with lauric acid in the presence of magnesium carbonate, the lipopeptide N-lauroylglycylglycine was formed. Such compounds are proposed to have been critical precursors to the development of life.

As a unifying concept of bonding, electronegativity has been widely applied but gets only a limited treatment in most general chemistry texts.

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