Donors structures

The rate of transfer hydrogenation also varies markedly with donor structure. For cyclohexene, 1 -methylcyclohexene, l-methyl-4-isopropyl-cyclohexene,and l-methyl-4-f-butyIcycIohexene as donor in the above hydrogenations, after 1 min the reduction was 11, 78, 99, and 99% complete, respectively (97). 

Similarly, the addition of a variety H donors under photochemical conditions generally provided mixtures of products 52-54 (Scheme 14) (77CL1127). When xanthene was used as the hydrogen donor, structures 52 usually prevailed. On the other hand, no structures 52 were detected in the case of etheral donors such as tetrahydrofuran or 1,4-dioxane. 

The second ligand type consists of a large group of cyclic compounds incorporating numbers of ether functions as donors. Structure (22) illustrates a typical example. Such crown polyethers usually show strong complexing ability towards alkali and alkaline earth ions but their tendency to coordinate to transition metal ions is less than for the above... 

Vast synthetic effort was subsequently employed to produce new conducting charge-transfer (CT) salts incorporating TTF-based donor structures. The first... 

Clinically Available NO Donors Structures and Mechanism of Action... 

In addition to organic nitrates, many other chemicals can be transformed into NO in vitro or in vivo. Due to the diversity of NO donor structures, the pathway for each class of compounds to generate NO could differ significantly, e.g., enzymatical vs. 

The type of O2 adduct depends on the donor structure. For example, tetraphenyl-oxirane forms an ozonide (78), " 1,4-bifunctional radical cations form dioxanes (79) conjugated dienes form cyclic adducts (80) and ergosteryl acetate (81) forms the 5a,8fl-peroxide (82) at —78... 

Recognition of the glycosyl-donor structure by the transferase enzyme also shows high specificity. 

A large number of bridge N-donor structures exist (Sec. 2.2A.2), for example 157,160,162,163,164,191,197, and 200 203. In this respect, it is necessary to note Ref. 78, where it is shown that amidines form (3.66), additionally to chelate structures of the type 625, the bimetallic complexes 626 with a bridge function of the ligand ... 

Baca, S.G, Pope, S.J.A., Adams, H., and Ward, M.D. (2008) Cyanide-bridged Os(lI)/Ln(lII) coordination networks containing [Os(phen)(CN)4 ] as an energy donor structural and photophysical properties. Inorganic Chemistry, XI,... 

The next lowest energy local minimum on the PES of Ph0H(H20)i is occupied by the PhOH-u i-2 structure shown in Figure 48. Here, phenol acts as an acceptor of the hydrogen bond and, compared to the hydrogen bond donor structure, it is less favourable, by 1.11 kJmol at the HF/A levef . The energy gap between PhOH-wi-l and PhOH-u i-2 decreases slightly to 10.8 kJmol after ZPVE correction and increases to 11.2 kJmol when both structures are recalculated at the MP2(sp)/A level. 

Imidazole and Related Donors. Structural models for the co-ordination geometries of a Cu-Cu" redox couple in copper enzymes suggest a mechanism for where both electrons and protons are involved a model has been characterized bis(imidazole) copper(ii) diacetate (102). Dark green crystals of [Cu(caffeine)Cl2,H20] in which copper is tetragonal pyramidal distorted towards trigonal bipyramidal have been characterized Cu—Ni = 1.98 A,Cu—0(H20) = 1.96 A, Cu—Cl = 2.32,2.25 A. Dinitrato-2,6-bis-[l-(phenylimino)ethyl]pyridinecopper(ii) (103) contains a planar... 

Figure 17 Some examples of alternative nucleotide sugar donors that have been produced chemoenzymatically. Differences from a natural nucleotide sugar donor structure, UDP-glucose, are highlighted in red.

Table 14.4. Expansion coefficients Co(i) at the acceptor-donor structures in the ground-state wave function at various stages of the 8 2 substitution reaction of ethylene reactant (R), intermediate (I), and product (P). The most important contributions are in bold. ...

Then, a problem appeared how do you express one picture by another In particular, this has been important for expressing the MO picture in the AD one. More specifically, we are interested in calculating the contribution of an acceptor-donor structure in the Slater determinant written in the MO formalism, where the MOs are expressed by the donor ( ) and acceptor (x and x" ) orbitals in the following way ... 

Acceptor-Donor Structure Contributions in the MO Configuration el93... 

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