Central structural unit

The use of KN(SiMe3)2 as metalating reagent enabled us to prepare the dimeric potassium derivative [(Cy7Si70i2)2Kg(DME)4] (18) as a crystalline solid, which was structurally characterized by X-ray diffraction (Scheme 7). Here again a box-shaped KgOg polyhedron forms the central structural unit. Four potassium ions are coordinated by DME (1,2-dimethoxyethane) ligands. ... 

The formation of complexes with the [NTc(/u-0)2TcN] central structural unit has parallels in molybdenum chemistry, where isostructural complexes such as [ MoO(S2CNEt2) 2(M 0)2] are well established. In the MoO system, the differences for the 0x0 ligand compared to the nitrido ligand are again obvious, since the Mo sites about 0.73 A above the basal plane of the square pyramid, compared to 0.65 A in the technetium case. ... 

Structural nomenclature for more complex polynuclear compounds is based on the description of the fundamental structural unit, and a logical procedure for numbering the atoms of the fundamental or central structural unit. For nonlinear clusters, descriptors such as tetrahedro, dodecahedro, etc. have traditionally been used to describe a central structural unit (CSU). However, synthetic chemistry has now advanced far beyond the utility of the limited CSU set associated... 

Central structural units may thus be specifically identified and numbered for nomenclature practices. However, many symmetrical CSUs may not require a full set of locants in the name because these compounds may exhibit only one possible isomer. 

The reaction of the amino imidazolium salt hydrobromide with silver(I) oxide yields the corresponding silver(I) carbene complex (see Figure 4.29) that has the same central structural unit as the lithium complex [35]. 

Star-shape polymers. Star polymers contain three or more polymer chains emanating from a central structural unit (Fig. 14.2). 

While the puckered (LiN)3 ring is the central structural unit in these unsolvated amides, a ring-ladder interconversion may be observed upon addition of coligand to the lithium amides. This structural rearrangement follows the same pattern as observed in the chemistry of monofunctional... 

Lactones are normally stable compounds, which have found ample application as synthetic intermediates, and, quite recently, have been detected as the central structural unit in physiologically active natural products like obaflorin (123) and lipstatin (124). Characteristic applications of 3-lactones in synthesis are the stereospecific CO2 elimination to form di- and tri-substituted alkenes (e.g. from 125 equation 40) or Grignard addition to the carbonyl group e.g. equation 41). Particularly useful is the formation of 3-lactone enolates (126), which react with a variety of electrophiles (EX) wiA high stereocontrol (equation 42). Organocuprates may be used in chain elongations to form 3-branched carboxylic acids (equation 43). ... 

IR-9.2.5.7 Polynuclear clusters symmetrical central structural units IR-9.3 Describing the configuration of coordination entities IR-9.3.1 Introduction... 

Polynuclear clusters symmetrical central structural units... 

Extended conjugated systems of jr-electrons make these compounds promising candidates for various elecfronic devices [49, 50] and solar cell compo-nenfs [51,52]. These macrocycles provide a variefy of subsfifufion sifes which can be used fo create compounds with controlled electron donor/acceptor properties [53, 54]. In nature, metal-containing macrocycles are present as central structural units in many substances involved in biochemical redox reactions [55]. 

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