N = 4 or 6 seems to give most acceptable results, although somewhat larger values of N are within the error of calculation (see Yoshida et al., 1973). Theoretical calculation of the coordination number depends on the value of V0, which is uncertain in water and ammonia. CKJ conclude that for a reasonable value of V0, between 0.5 and -0.5 eV, N = 4 or 6 is most appropriate for both water and ammonia. [Pg.174]

In a study of the methane complex [(diimine)Pt(CH3)(CH4)]+ (diimine = HN=C(H)-C(H)=NH), relevant to the diimine system experimentally investigated by Tilset et al. (28), theoretical calculations indicate preference for the oxidative addition pathway (30). When one water molecule was included in these calculations, the preference for oxidative addition increased due to the stabilization of Pt(IV) by coordinated water (30). The same preference for oxidative addition was previously calculated for the ethylenediamine (en) system [(en)Pt(CH3)(CH4)]+ (151). This model is relevant for the experimentally investigated tmeda system [(tmeda)Pt(CH3)(solv)]+ discussed above (Scheme 7, B) (27,152). For the bis-formate complex Pt(02CH)2, a a-bond metathesis was assumed and the energies of intermediates and transition states were calculated [Pg.290]

Traube s rule accommodates the balance between hydrophobicity and hydro-philicity. It has been extended somewhat and formalized with the development of quantitative methods to estimate the surface area of molecules based on their structures [19, 237]. The molecular surface area approach suggests that the number of water molecules that can be packed around the solute molecule plays an important role in the theoretical calculation of the thermodynamic properties of the solution. Hence, the molecular surface area of the solute is an important parameter in the theory. In compounds other than simple normal alkanes, the functional groups will tend to be more or less polar and thus relatively compatible with the polar water matrix [227,240]. Hence, the total surface area of the molecule can be subdivided into functional group surface area and hydro carbonaceous surface area . These quantities maybe determined for simple compounds as an additive function of constituent groups with subtractions made for the areas where intramolecular contact is made and thus no external surface is presented. [Pg.142]

A colorless, colloidal precipitate was formed and stirred thoroughly for about 15 minutes, whereupon it was filtered by suction. The raw product thus obtained was washed with water until It contained only about Va% water-soluble salts. After drying for 12 hours In a vacuum apparatus at 60°C and under a pressure of 12 mm Hg, the product had the form of hard pieces. The pieces were comminuted to powder in a ball mill and the powder was passed through a sieve (3,600 meshes per cm ). The small residue on the sieve was again pulverized and passed through the same sieve. The yield was 870 g, or 99% of theoretical, calculated on the assumed formula [Pg.893]

Benzotriazole can exist in two tautomeric forms, l-//-benzotriazole (6.46, R = H) and 2-/f-benzotriazole. If the aromatic ring contains a substituent, the 1- and 3-nitrogen atoms of the triazole are not equivalent, and therefore a 3-//-benzotri-azole derivative can also exist. The equilibrium between the 1 -H and 2-H tautomers of benzotriazoles is strongly on the side of the 1 -H tautomer, in contrast to triazole where the 2-H tautomer is dominant. Tomas et al. (1989) compared experimental data (enthalpies of solution, vaporization, sublimation, and solvation in water, methanol, and dimethylsulfoxide) with the results of ab initio theoretical calculations at the 6-31G level. [Pg.132]

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