Bonding states

There is a controversy about tire bonding state of tire sulphur. Most evidence suggests tliat it is bound in tire fonn of a tliiolate [122], while x-ray diffraction suggests tliat tire sulphur atoms may dimerize [147]. Flowever, not all of tire observed overstmctures can be explained witli tliis latter assumption. 

The charge distribution may be symmetrical when the system possesses similar nitrogen atoms and identical or unsymmetrical nuclei approaching more or less a polyene-like bond state when the nuclei are of different... 

Stability of the chromophore was observed usiag uv-vis spectroscopy, the authors conclude that this sol—gel method of chromophore encapsulation does not provide any real thermal or oxidative protection in either the covalendy or noncovalently bonded state. 

In general, collectors for the flotation separation of sulfides and precious metals contain at least one sulfur atom ia an appropriate bonding state. 

TABLE 2.4. "Back of the Envelope" Estimation of the Energies of Valence-Bond States of the X- + CH3X- XCH3 +X- SN2 reaction ... 

FIGURE 2.7. (a) Three active pz orbitals that are used in the quantum treatment of the X + CH3-Y— X-CH3 + Y Sw2 reaction, (b) Valence-bond diagrams for the six possible valence-bond states for four electrons in three active orbitals, (c) Relative approximate energy levels of the valence-bond states in the gas phase (see Table 2.4 for the estimation of these energies). 

The coadsorption of oxygen as well as of other electronegative additives on metal surfaces favors in general the 7t-bonded molecular state of ethylene, as the latter exhibits, compared to the di-o bonded state, a more pronounced electron donor character and a negligible backdonation of electron density from the metal surface. 

One can then ask What is the rate at which the strongly bonded state is populated during the TPD and cyclic voltammetric experiments of Figures 5.2b and 5.2c The answer is clear It is the rate ofO2 supply to the catalyst, i.e. I/2F. 

The revision leads to a difference of 0.06 A. between the interatomic distance in the normal oxygen molecule and the sum of the double-bond radii. This may be attributed to the presence of an unusual structure, consisting of a single bond plus two three-electron bonds. We assign this structure both to the normal 2 state, with ro = 1.204 A., and to the excited 2 state, with ro = 1.223 A., the two differing in the relative spin orientations of the odd electrons in the two three-electron bonds. We expect for the double-bonded state the separation n 1.14 A. 

Atom-bonding state sp2 only sp only sp2, sp, sp (variable ratio)... 

M. J. Taylor, Metal-to-Metal Bonded States of the Main Group Elements, Academic Press, London, 1975, Ch. 3. Describes M—M bonded compounds of Al, Ga, In and Tl. 

State, as shown in Fig. 10.8 [65]. The "trefoil bonding state, previously proposed and predicted to exist in aromatic hydrocarbon annulene molecules, is finally encountered, albeit in an extended intermetallic network [65]. This also highlights the important role of interactions between incompletely filled lone pairs in the stabilization of low-dimensional anion structures. 

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