Dipolar metal complexes bridges

Figure 3.31 As (due to orientational response of aqueous solvent) versus e, calculated for ET in a large binuclear transition metal complex (D (Ru2+/3+) and A (Co2+/3+) sites bridged by a tetraproline moiety) molecular-level results obtained from a nonlocal polarization response theory (NRFT, solid lines) continuum results are given by dashed lines, referring to numerical solution of the Poisson equation with vdW (cont./vdW) and SAS (cont./SAS) cavities, or as the limit of the NRFT results when the full k-dependent structure factor (5(k)) is replaced by 5(0) 5(k) for bulk water was obtained from a fluid model based on polarizable dipolar spheres (s = 1.8 refers to ambient water (square)). For an alternative model based on TIP3 water (where, nominally, 6 = ), ambient water corresponds to the diamond. (Reprinted from A. A. Milishuk and D. V. Matyushov, Chem Phys., 324, 172. Copyright (2006), with permission from Elsevier).

Finally, two potential models for the Mo and Fe sites of sulfite oxidase have been prepared in which a hydrotris(3,5-dimethylpyrazolyl)borate complex of oxomolybdenum(V) is covalently attached to one of the phenyl rings of a tetraphenylporphinatoiron(III) derivative in which three phenyl rings carry / -Me groups and the other is either a 2,3- or 3,4-catecholate. Although the metals are not directly bridged in these complexes, they are held at fixed Mo - Fe distances. EPR spectroscopy at 4K shows distance-dependent static dipolar coupling between the Mo and Fe centers. At 77 K the dipolar coupling is modulated by rapid relaxation of the Fe center. Coordination of two A-methylimidazoles to the Fe centers produce S = l/2)Fe-(5 = 1/2)mo coupled systems that are not only... 

In this section, selected examples are described of dipolar second-order NLO chromophores in which an organometallic or coordination moiety may act as the donor (D), the acceptor (A) or even as the n-bridge connecting D to A. Representative examples of noncentrosymmetric bimetallic complexes containing metal-based fragments used as electron-donating and electron-accepting moieties, are also discussed. 

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