Atomic transition metal ion

Atomic metal ion-hydrocarbon reactions bond dissociation energies for fragments, 15,16t endothermic reactions, 13,15,17f Atomic transition metal ion reactions development of approach for real-time measurements of dissociation kinetics, 39 ion beam apparatus, 12,14f studies of... 

The preference for the cis and facial structures has been explained as arising from strong 4,-t4 bonding between the metal and sulfur atoms transition metal ions can form two 7t-bonds at 90° and, consequently, of the isomeric cis and irons structures, wherein only the two sulfur atoms of the four donor atoms can form d -d bonds, the cis isomer is the more stable. An alternative explanation is that the cis configuration is due to weak non-bonded S—S interaction. Recent dipole moment and and F NMR data on Ga and In complexes indicate a facial-meridional (cis-trans) equiUbrium in solution. For these non-transition elements d -d bonding cannot arise consequently, the explanation of d -d stabilization of the configurations for transition metal complexes appears to be the correct one. 

Chen, R. and li, L. (2001) Reactions of atomic transition-metal ions with long-chain alkanes. J. Am. Soc. Mass Spectrom., 12, 357-375. 

Elkind, J. L. Armentrout, P. B., State-specific reactions of atomic transition metal ions with H2, HD and Dji Effects of d orbitals on chemistry , J. Phys. Chem. 1987, 91, 2037-2045. 

An atom or a molecule with the total spin of the electrons S = 1 is said to be in a triplet state. The multiplicity of such a state is (2.S +1)=3. Triplet systems occur in both excited and ground state molecules, in some compounds containing transition metal ions, in radical pair systems, and in some defects in solids. 

Most of the free-radical mechanisms discussed thus far have involved some combination of homolytic bond dissociation, atom abstraction, and addition steps. In this section, we will discuss reactions that include discrete electron-transfer steps. Addition to or removal of one electron fi om a diamagnetic organic molecule generates a radical. Organic reactions that involve electron-transfer steps are often mediated by transition-metal ions. Many transition-metal ions have two or more relatively stable oxidation states differing by one electron. Transition-metal ions therefore firequently participate in electron-transfer processes. 

Crystal-field theory (CFT) was constructed as the first theoretical model to account for these spectral differences. Its central idea is simple in the extreme. In free atoms and ions, all electrons, but for our interests particularly the outer or non-core electrons, are subject to three main energetic constraints a) they possess kinetic energy, b) they are attracted to the nucleus and c) they repel one another. (We shall put that a little more exactly, and symbolically, later). Within the environment of other ions, as for example within the lattice of a crystal, those electrons are expected to be subject also to one further constraint. Namely, they will be affected by the non-spherical electric field established by the surrounding ions. That electric field was called the crystalline field , but we now simply call it the crystal field . Since we are almost exclusively concerned with the spectral and other properties of positively charged transition-metal ions surrounded by anions of the lattice, the effect of the crystal field is to repel the electrons. 

When a reaction appears to involve a species that reacts as expected for a carbene but must still be at least partially bound to other atoms, the term carbenoid is used. Some carbenelike processes involve transition metal ions. In many of these reactions, the divalent carbene is bound to the metal. Some compounds of this type are stable, whereas others exist only as transient intermediates. In most cases, the reaction involves the metal-bound carbene, rather than a free carbene. 

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