Binding and Reactivity

Dinitrogen has been shown to adopt an end-on bonding arrangement in those phosphine-containing complexes that have been isolated and characterized. In most of these complexes, dinitrogen bonds in a linear end-on arrangement either to one metal G (e.g., 15, 23, 43, 50, 52, and 

Organophosphine ligands are particularly successful in helping the metal provide a favorable coordination site that is sufficiently electron-rich to provide strong back-donation into the vacant dinitrogen tt -orbitals and help stabilize the metal-dinitrogen bond. 

So far, no example of a simple side-on bonded dinitrogen complex has been reported. A common problem in working with dinitrogen complexes is the facile loss of dinitrogen that is very frequently observed. 

The reactivity of coordinated dinitrogen toward electrophiles, nucleophiles, and radicals is dependent upon many factors, particularly the charge distribution within the dinitrogen-metal unit that results from the synergistic-bonding pattern. Attempts to determine the charge distribu- 

The Lewis base behavior of coordinated dinitrogen has been studied and related to In many cases, stable Lewis base-Lewis acid 

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Bulk and Steric Parameters in Binding and Reactivity of Bioactive Compounds... 

Pearson, P.G., Omichinski, J.G., McClanahan, R.H., Soderlund, E.J., Dybing, E. Nelson, S.D. (1993a) Metabolic activation of tris(2,3-dibromopropyl) phosphate to reactive intermediates. 1. Covalent binding and reactive metabolite formation in vitro. Toxicol, appl. Pharmacol., 118, 186-195... 

The binding and reactivity of dinitrogen in transition metal complexe 718... 

Zhou JS,Tran ST, McLendon G, Hoffman BM. Photoinduced electron transfer between cytochrome c peroxidase (D37K) and Zn-substituted cytochrome c probing the two-domain binding and reactivity of the peroxidase. J Am Chem Soc 1997 119 269-77. 

Kubas GJ. Fundamentals of H2 binding and reactivity on transition metals underlying hydrogenase function and H2 production and storage. Chem Rev 2007 107 4152-205. 

The position of the Fermi level and the nature of the states at that level clearly is an important factor in determining binding and reactivity on metal surfaces. The point is not original to this work, but has been clearly discussed in several contributions to the literature.56b,83c Attention is directed to a particularly interesting discussion of how the local DOS at the Fermi level is affected by chemisorption.83d... 

CD spectroscopy has also been used to study the metal-binding and reactivity properties of iron- and manganese-containing SODs. These enzymes metabolize the superoxide ion radical O2 into molecular oxygen and hydrogen peroxide. The Fe- and Mn-SOD enzymes are strictly metal specific. Jackson and Brunold show that, despite the fact that Fe replacement of Mn in the Mn-SOD enzyme [(Mn Fe)-SOD] results in an inactive enzyme, the CD spectrum of wild-type Fe-SOD and (Mn - Fe)-SOD are remarkably similar. This suggests that the destroyed enzyme activity, upon replacement of the metal, does not occm via distortion of the enzyme active site. 

The structure of plastocyanin is known at a highly refined level, which allows interesting hypotheses on which part of the molecule is involved in interactions permitting electron transfer [73]. Several areas on the surface of the molecule have been modified with chemical reagents, which can change the binding and reactivity [74], which are highly sensitive to electrical interactions, as shown by the influence of cations on the rate of electron transfer (see e.g. Refs. 68 and 75). 

This equation implies the total reaction rate relative to the rate of hydrolysis in the presence of an acceptor. This ratio was found to depend only on the structure of the acceptor but to be independent of both the structure and the concentration of the donor galactoside. Thus, good binding and reactivity for a given acceptor will lead to a large degree of transglycosylation. 

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