Sulfur ionization energies

Experimental and calculated (CNDO/S) vertical ionization energies have been measured for pyrazol-3-ine-5-thiones (108 R = H, Me). These compounds exhibit an intense low-energy band (7.55-7.60 eV) corresponding to the ionization of both a thiocarbonyl tt-electron and the sulfur n electron (78JA1275). 

The ionization energy of the sulfur atom shows that it is even more reluctant than phosphorus to lose electrons. The common compounds of sulfur are the sulfides, which may be formed by reactions of elemental sulfur with a large number of metals. Typical reactions are... 

The group of the chalcogens sulfur, selenium and tellurium is a typical triad of the more electronegative nonmetals with relatively high-ionization energies, relatively strong element-element bonds and a clear tendency to form mono-and polyatomic anions (Table 1). 

The photoelectron spectrum of 2,1,3-benzoselenadiazole (1), 2,1,3-benzothiadiazole and their tetrafluoro derivatives were measured. Replacement of sulfur by selenium did not appreciably alter the 7t molecular-orbital ionization energies <91KGS563). 

From what you know of the relationship between ionization energies, electron affinities, and electronegativities, would you expect the addition of some d character to a hybrid to raise or lower the electronegativity for example, will sulfur be more electronegative when hybridized spi or jp [Pg.649]

There has been a great deal of interest in recent years in photoelectron spectroscopy (PES) of the isomeric A,B-diheteropentalenes containing sulfur, selenium and nitrogen. This technique has offered for the first time direct experimental evaluation of the ionization energies of the valence electrons. The sulfur- and selenium-containing heteroaromatics appear to be the class most investigated by PES. The ionization potentials of various A,B-diheteropentalenes, are presented in Table 3. 

The highest occupied molecular orbital (HOMO) in formaldehyde and heteroaldehydes, H2C=E, is the lone pair at E (nE), and the second highest MO (SOMO) is the C=E 77-bonding orbital. The LUMO is the 77 CE orbital composed of the antibonding combination of pz(C) and pz(E). The ionization energy of the HOMO in formaldehyde is 10.88 eV and of the SOMO 14.5 eV, as determined by photoelectron spectroscopy.33 The ionization energy of the HOMO and the SOMO both decrease considerably when the oxygen atom in formaldehyde is replaced by sulfur or selenium (see Fig. 1, data are compiled from Refs. 33-37). 

Ionization energy generally increases from left to right across a row of the periodic table and decreases from top to bottom down a group. Chlorine should have a larger E than its neighbor sulfur, and selenium should have a smaller E than sulfur. 

Kornyshev and Schmickler claimed (28) that the most important parameters that determine the charge of the adsorbate are the atom ionization energies, the work function of the metal, and the electronic affinities. This last parameter is taken into account by Barbier et al. (25) to explain the adsorption behavior of sulfur on noble metals. Following this explanation, the smaller the difference of electronic affinities between sulfur and metal, the more covalent the metal-sulfur bond. 

Sulfur lone pair ionization energies of silthianes. 210... 

Sample Which atom should have a smaller first ionization energy, oxygen or sulfur ... 

Since the outer electron in sulfur experiences more shielding, it will be easier to pull off. Therefore, S has the smaller first ionization energy. 

Conformational analysis of 1,4,7-trithiacyclononane 10 in the gas phase was done using ab initio molecular orbital calculations at the HF and MP2 levels as well as microwave and photoelectron spectroscopies. The photoelectron spectroscopic data showed evidence for at least two conformations with different ionization energies. Using the calculated photoelectron spectra, the observed sulfur 3p-ionization peaks can be assigned to Cj and U2 conformations. Forty of the observed microwave transitions can be assigned to a Cj symmetry, while additional microwave lines are believed to be due to a nonrigid U2-symmetry conformation <1997PCA9180>. 

Ordinarily, the first ionization energy increases as we go across a period, so we might expect sulfur to have a greater ionization energy than phosphorus. However, in this case the fourth p electron in sulfur must be placed in an already occupied orbital. The electron-electron repulsions that result cause this electron to be more easily removed than might be expected. ... 

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