Molecular metal, neutral

Receptor and substrate are terms describing the species involved in complex formation. Throughout the chapter the receptor will refer tp the macrocyclic ligand, the substrate to other interacting species. Substrates may be metal or molecular catibns, neutral molecules, or atomic or molecular anions. The terms receptor and substrate imply that the complex formed has the well-defined structural and chemical properties of a supermolecule, as in biological receptor-substrate associations. They exclude species formed only in the solid state (clathrates). They are also easily converted and understood in many languages. 

Historically, the concept of coordination chemistry was associated with complexation of a metal cation (Lewis acid) by a ligand behaving as a Lewis base. Such was traditionally the case for macrocyclic molecules as ligands. In the early 1970s, however, the concept of coordination chemistry was extended in the area of macrocyclic chemistry to include molecular cations, neutral molecules and anions as substrates. Complexes of all of these species are to be included in the scope of this chapter section. Examples of the types of substrates are discussed below. 

The first molecular metal based on single component and electrically neutral metal complex, [Ni(tmdt)2] (tmdt = trimethylenetetrathiafulva-lenedithiolate. Figure 4.17) was reported in 2001. Details of this compound and some other single component molecular conductors are given in Section 4.3.4 and in several review articles. 

Davis, W.B. and Hefferlin, R. An Atlas of Forecasted Molecular Data II Vibration Frequencies of Main-Group and Transition-Metal Neutral Gas-Phase Diatomic Molecules in the Ground State (in preparation). 

Telechelic Ionomers. Low molecular weight polymers terminated by acid groups have been treated with metal bases to give ionomers in which the cations can be considered as connecting links in the backbones (67—71). The viscoelastic behavior of concentrated solutions has been linked to the neutralizing cation. 

These acids are less stable, less soluble and less acidic than the corresponding sulfonic acids. The common impurities are the respective sulfonyl chlorides from which they have been prepared, and the thiolsulfonates (neutral) and sulfonic acids into which they decompose. The first two of these can be removed by solvent extraction from an alkaline solution of the acid. On acidification of an alkaline solution, the sulfinic acid crystallises out leaving the sulfonic acid behind. The lower molecular weight members are isolated as their metal (e.g. ferric) salts, but the higher members can be crystallised from water (made slightly acidic), or alcohol. 

At any interface between two different phases there will be a redistribution of charge in each phase at the interface with a consequent loss of its electroneutrality, although the interface as a whole remains electrically neutral. (Bockris considers an interface to be sharp and definite to within an atomic layer, whereas an interphase is less sharply defined and may extend from at least two molecular diameters to tens of thousands of nanometres the interphase may be regarded as the region between the two phases in which the properties have not yet reached those of the bulk of either phase .) In the simplest case the interface between a metal and a solution could be visualised as a line of excess electrons at the surface of the metal and an equal number of positive charges in the solution that are in contact with the metal (Fig. 20.2). Thus although each phase has an excess charge the interface as a whole is electrically neutral. 

Macropolycyclic ligands, 2,942 classification, 2,917 metal complexes binding sites, 2, 922 cavity size, 2,924 chirality, 2, 924 conformation, 2,923 dimensionality, 2, 924 electronic effects, 2, 922 shaping groups, 2,923 structural effects, 2,922 molecular cation complexes, 2,947 molecular neutral complexes, 2,952 multidentate, 2,915-953 nomenclature, 2,920 Macro tetrolide actins metal complexes, 2,973 Macrotricycles anionic complexes, 2,951 cylindrical... 

In the case of adsorption of neutral polar molecules, the effect on is more tractable in molecular terms.7,89 Adsorption is believed to occur79 by displacement of solvent molecules close to the metal surface which are replaced by adsorbate molecules.90 At 0 = 0 (no adsorbate),Ea 0 is more conveniently written from Eq. (26) as... 

In a systematic study, it was demonstrated that, using a specially designed bulky benzamidinate ligand, it is possible to isolate mono(amidinato) dialkyl complexes over the full size range of the Group 3 and lanthanide metals, i.e., from scandium to lanthanum. The synthetic methods leading to the neutral and cationic bis(alkyls) are summarized in Scheme 56. Figure 18 displays the molecular structures of the cations obtained with Sc, Gd, and La. ... 

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