Carbon atom, naked

Palladium metallic clusters have been prepared at room temperature by sonochemical reduction of Pd(OAc)2 and a surfactant, myristyltrimethylammonium bromide, in THE or MeOH [160[. It is noteworthy that nanosized amorphous Pd is obtained in THE, but in a crystalline form in MeOH. In this solvent, and in higher homologous alcohols, sonolysis of tetrachloropalladate(II) leads to Pd nanoclusters in which carbon atoms, formed by complete decomposition of the solvent, can diffuse. This results in an interstitial solid having the formula PdQ (0 < x < 0.15) [161]. Noble metal nanoparticles of Au, Pd, and Ag are obtained by sonicating aqueous solutions of the corresponding salts in the presence of a surfactant, which largely stabilise the naked col-... 

Carbodiphosphoranes C(PR3)2 and related ligands CL2 which are also termed double ylides differ from the other carbon ligands which are discussed in this volume in the number of lone electron pairs at the carbon donor atom. Ylides, carbenes, allenylidenes, and cumulenylidenes have one lone electron pair but carbodiphosphoranes have two lone electron pairs with a and n symmetry. The bonding situation in a carbodiphosphorane (a special class of CL2 compounds, abbreviated as CDP) is best described in terms of donor-acceptor bonding between the phosphane ligands which serve as a donor and a naked carbon atom in an... 

In Chapter 4 we learned how silicates give clay its plastic properties. In this chapter we will see how carbon atoms bond in chain arrangements to produce organic compounds that can have the plastic properties of clay. We will study sculpture and describe molecular forms as sculptures. Finally, we will see how organic molecules, microscopic sculptures, have the same properties as macroscopic sculptures, which are visible to the naked eye. 

Figure 12.8.2(a) shows the molecular structure of Na4Mg2(TMP)6(C6H4), in which the N atom of each tetramethylpiperidinide is bonded to two metal atoms to form a cationic 12-membered (Na-N-Na-N-Mg-N-h ring. The mixed metal macrocyclic amide acts as a host that completely encloses a 1,4-deprotonated benzenediide guest species whose naked carbon atoms are each stabilized by a covalent Mg-C bond and a pair of Na- C n interactions. 

In the realm of all-carbon ligands in the formation of transition-metal complexes, the naked carbon atom holds a special position. Based on the geometry of metal-carbon interaction, these compounds can be divided into four classes terminal carbide (I), 1,3-dimetallaallene (II), C-metalated carbyne (III), and carbido cluster (IV) ... 

There are two well-characterized examples of a naked carbon atom bound by a triple bond to a metal center (Fig 14.3.8). The molybdenum carbide anion [CMo N(R)Ar 3]- (R = C(CD3)2(CH3), Ar = C6H3Me2-3,5), an isoelectronic analog of NMo N(R)Ar 3, can be prepared in a multistep procedure via deprotonation of the d° methylidyne complex HCMo N(R)Ar 3. The Mo=C distance of 171.3(9) pm is at the low end of the known range for molybdenum-carbon multiple bonds. In the diamagnetic, air-stable terminal ruthenium carbide complex Ru(=C )C12(LL/)(L = L = PCy3, or L = PCy3 and L = l,3-dimesityl-4,5-dihydroimidazol-2-ylidene), the measured Ru-C distance of 165.0(2) pm is consistent with the existence of a very short Ru=C triple bond. 

The carbide-centered polynuclear transition-metal carbonyl clusters exhibit a rich variety of structures. A common feature to this class of carbide complexes is that the naked carbon is wholly or partially enclosed in a metal cage composed of homo/hetero metal atoms, and there is also a subclass that can be considered as tetra-metal-substituted methanes. The earliest known compound of this kind is FesC(CO)i5, in which the carbon atom is located at the center... 

Molecular structures of some transition-metal clusters containing a naked carbon atom. 

The carbenoid reactions leading to cyclopropanes in/ermolecularly have been reviewed extensively so that we can restrict our discussion to some interesting i mromolecular reactions, the so-called carbon atom insertions5 or naked carbon-atom insertions 6) (for instance Eq. (1)) ... 

Part of the exhilaration of the fullerenes is the shock that an old reliable friend, the carbon atom, has for all these years been hiding a secret life-style. We were all familiar with the charming versatility of carbon, the backbone of organic chemistry, and its infinite variation in aromatic and aliphatic chemistry, but when you got it naked, we believed it existed in two well-known forms, diamond and graphite. The finding that it could exist in a shockingly new structure unleashes tantalizing new experimental and theoretical ideas [33],... 

Dicyanopolyynes-60 These contain linear chains of naked carbon atoms with alternating single and triple bonds the ends are capped with C=N groups as in 7-X. 

Except for the fullerenes (see later), carbon atoms seldom coordinate a metal atom a well-characterized example of a naked carbon atom is a molybdenum carbide prepared, in a multistep procedure, by removing a terminal proton from a corresponding methylidyne species ... 

The description of a heteroatom as interstitial is well-defined when it is completely encapsulated within a polyhedron of metal atoms as, for example, in the octahedral cluster [Ru6C(CO)i7].l l There is, however, a large number of clusters containing naked main-group atoms in a variety of coordination modes which cannot be classified as readily. For example, the carbon atom in [Ru5C(CO)i5] lies slightly below the basal plane of a square pyramidal cluster framework where it... 

While the aforementioned lonophores are Streptomyces metabolites, the crown polyethers. the depicted prototype of which is dlcyclohexyl-18-crown-6, are synthetic W. Although they lack the intricate conformations of the natural lonophores arising from multiple asymmetric carbon atoms, their molecular llgeindlng properties are analogous. While they are less efficient ion carriers, their lack of labile linkages confers Increased chemical stability they find extensive use in org inlc synthesis for solubilizing electrolytes, e.g. K " enolates, in nonpolar solvents thereby providing reactive naked anions ( ). 

Experiment 12.4 Carbonizing and decarbonizing of iron (schematic representation) Iron can be carbonized by annealing in charcoal powder at approx. 1,000 °C. This means that the carbon atoms move into it. The changes of the grain stmcture at the border of the sample are visible to the naked eye as a dark area, but they can be examined in more detail with a microscope. The iron can also be decarbonized by heating in an oxidizing flame or in a furnace in air. 

In recent years a great number of transition metal clusters containing an interstitial carbon atom has been prepared and now they constitute a growing field of metal carbide clusters . A far less number of nitride clusters and several compounds containing a naked P, As, or S atom embedded within metal clusters have been reported, such as... 

PARTICLE. Any discrete unit of material structure the particulate basis of matter is a fundamental concept of science. The size ranges of particles may be summarized as follows (1) Subatomic protons, neutrons, electrons, deuterons, etc. These are collectively called fundamental particles. (21 Molecular includes atoms and molecules with size ranging from a few angstroms to half a micron. (3) Colloidal includes macromolecules, micelles, and ullrafiiic particles such as carbon black, resolved via electron microscope, with size ranges from 1 millimicron up to lower limit of the optical microscope (1 micron). (4) Microscopic units that can be resolved by an optical microscope (includes bacteria). (5) Macroscopic all particles that can be resolved by the naked eye. 

The recoil chemistry of carbon-11 in liquid C5-C7 hydrocarbons has been investigated by Clark The recoil atoms have been produced in the (y,n) reaction. The study of the product yields of ethane, ethylene and acetylene (as well as of methane) from different target molecules has been the main concern in this work. Iodine affected the yields of all the volatile products except acetylene. Acetylene-the principal products in all the hydrocarbons investigated, is produced in hot reactions with naked atoms. Insertion of recoil fragments into C—H and C=C bonds leads to various C-labelled hydrocarbons. 

Bimetallic carbido bridged complexes (M=C=M) or metallated carb3me complexes (M=C-M) with a "naked" carbon [14] atom between two metal atoms are rare. Until now only the tetra-phenylporphinato [15] and phthalocyanato iron complexes [16], the W=C-Ru complex which is... 

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