Mononuclear systems

For single rings (i.e. mononuclear systems) up to ten atoms in size, there is no question but that Hantzsch-Widman names are overwhelmingly the most widely used, and specialists can be presumed to recognize them readily. However, when one of the trivial names of Table 1 can be used, it prevails almost exclusively. Thiophene will be immediately understood by specialists and most nonspecialists, whereas thiole will distract the reader s attention from the chemistry while he considers the writer s intention is the Hantzsch-Widman system indeed being used, or is it a typographical error Chemical Abstracts also uses these trivial names in its indexes. 

In view of the low Nin/Niin redox potential of [NiFe] hydrogenase, the search for low-potential Nin/Niin complexes not only with pure S-donor but also with mixed N/S environment has been of major interest, and significant advances in this field have been reported.298,299 Various mononuclear systems are listed in Figure 1 according to their redox potentials (usually in DMF). Homodinuclear Ni2 and heterodinuclear NiM complexes with N/S donor ligands, in particular... 

Kinetic studies of aquation of dinuclear [ traras-PtCl(NH3)2 2 (p-NH2(CH2)6NH2)]2+ established rate constants for the loss of the first and second chloride ligands (7.9 x 10-5 and 10.6 x 10-4s-1), and for the reverse anations (1.2 and 1.5M-1s-1). Reactivities here are very similar to those in analogous mononuclear systems [Pt(amine)3Cl]+ (204). A kinetic and equilibrium study of axial ligand substitution reactions... 

DR. ALBERT HAIM (State University of New York at Stony Brook) Dr. Meyer considered plots of optical transition energy versus 1/D(optical) minus 1/D(static) for various types of systems, some of which were binuclear and clearly delocalized. If instead, one considers a ruthenium(II) pentaamine bound to N-methyl-4,4,-bipyridinium, is this in any way different from the bridging situation In some instances there was a similar dependence for both the mononuclear systems and the binuclear systems. But some of these mononuclear systems did not seem to behave similarly. Is there any connection between whether that simple linear relationship works or not and whether the system is localized or delocalized ... 

One of the most studied mononuclear systems that usually leads to supramolecular networks and that also exhibits very rich photophysics and photochemistry is the [Au (CN)2] anion. This complex is among the most stable two-coordinate complexes of the transition ions, with a stability constant of 1037 [9], being reasonably stable to air, moisture, temperature and light, which could make it appropriate for practical applications. 

The most extensive group of molybdenum hydride complexes are those which contain phosphine ligands, and mononuclear systems with one to six hydride ligands have been identified. 

The mononuclear system has been developed largely by using the Mo(di-phosphane)2 [90] core. This site has the advantages that it is inert to protic attack and that it causes the metal to have a high affinity to N2 furthermore, the phosphane chelates remain bound to the metal during the reaction, and they occupy four of the six available coordination sites on the metal, leaving only two free positions where binding and activation of substrates can occur. 

This begs the question—are these MPS cells truly different from each other, or rather, specialized adaptive cell states 16 No single marker can be used to define if a cell is a macrophage. It has been suggested by Hume that, based on new insight provided by detailed characterizations of cells of the mononuclear system in recent years, a revised system for classifying immune cells of this lineage is overdue.16... 

Mossbauer spectra of paramagnetic complexes are generally analyzed in the framework of a spin Hamiltonian. The widely used software WMOSS9 can handle most of the situations that occur in practice. In the following, we briefly introduce the parameters that can be measured for simple systems. A spin Hamiltonian for Mossbauer and EPR analysis for mononuclear system may be written as... 

Work on Ptn terpyridyl complexes has not been limited to just mononuclear systems. Yam and coworkers have also investigated complexes wherein two platinum centers are attached through alkynyl bridges more specifically they studied chromophores of the type f Hu. tpy )Ptf( =C)nI>tf Hu. tpy)]2+ (3.10) [65], These structures exhibit photoluminescence in both the solid state and in room temperature solutions, the latter assigned as 3CT in nature mixed with 3IL and 3LLCT character. 

An interesting feature of hydrido transition metal-PF3 complexes is that apart from a few dinuclear systems (Section VI) only mononuclear systems are so far known and there is as yet no corresponding chemistry analogous to that of polynuclear carbonyl hydrido compounds. The trifluorophosphine metal hydrido compounds are usually highly acidic and can readily form metallate ions such as [M(PF3)m]x and [MH(PF3) r. 

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