Hydrocarbyl complexes stability

Hydrocarbonyl compounds, lanthanide complexes, 4, 4 ( -Hydrocarbyl)bis(zirconocene), preparation, 4, 906 Hydrocarbyl-bridged cyclopentadienyl-amido complexes, with Zr(IV), 4, 864 Hydrocarbyl complexes bis-Cp Ti hydrocarbyls reactions, 4, 551 structure and properties, 4, 551 synthesis, 4, 542 cobalt with rf-ligands, 7, 51 cobalt with rf-ligands, 7, 56 cobalt with ]4-ligands, 7, 59 cobalt with rf-ligands, 7, 71 heteroleptic types, 4, 192 homoleptic types, 4, 192 into magnetic metal nanoparticles via ligand stabilization, 12, 87 via polymer stabilization, 12, 87 into noble metal nanoparticles... 

Not considered within this review are the wide range of porphyrin and other nitrogen macrocycle-stabilized ruthenium and osmium hydrocarbyl complexes. Readers should see the following as a starting point for information on this type of alkyl/aryl, alkynyl, vinylidene, allenylidene, and carbene complexes. 

Interest in iridium hydrocarbyl complexes has been fueled by the higher thermodynamic stability of both Ir-C and Ir-H bonds in comparison to related compounds of rhodium. Therefore, iridium alkyl and aryl complexes have been frequently and successfully used as kinetically inert models for a variety of rhodium-catalyzed reactions allowing to collect intriguing mechanistic information on important industrial processes and organometallic reactions of academic interest. 

The highly electronegative metal ion affords the appropriate empty orbitals for the stabilization of the complex anion in the transition state. Both late and early transition metal alkyls are prone to this reaction, but its occurrence had to be particularly, invoked in the case of the early transition metals. Many similar reactions, such as the reaction of metal alkyls with other FIX compounds, could be described as if they followed this pathway, but the use of the term a-bond metathesis is restricted to those reactions in which one reacting species is a metal hydrocarbyl or metal hydride and the other reactant is a hydrocarbon or dihydrogen. Two reactions have been depicted in Fig. 4.34. There are, of course, borderline cases when the reacting hydrocarbon is acidic, as in the case of 1-alkynes, a direct attack of the proton at the carbanion can be envisaged. It has been proposed that acyl metal complexes of the late transition metals may also... 

As a result of the combined effect of the factors mentioned above, Pd monoaUcyl complexes are expected to be the least stable among hydrocarbyls (M = Pd, Pt). Such complexes are currently unknown, whereas monoaUcyl ft " complexes were among the first compounds characterized in C(sp )-0 reductive elimination reactions [16-19]. Among monoaryl Pd " derivatives only few were isolated to date aU of them are stabilized by fluoride ligands [26, 27]. No monohydrocarbyl Pd complexes supported by 0-donor ligand have yet been reported and characterized. The most studied O-ligated organopalladium(lV) complexes are diaryl dicarbox-ylates 13 shown in Fig. 7 [11, 12]. 

Several general review articles [19-41] dealing mostly with the synthesis of new actinide complexes confirm the broad and rapidly expanding scope of this field. Those reviews dealt with the structure, stability, and reactivates of complexes with cyclopentadienyl, dienyls (pentadienyl, cyclohexadienyl, indenyl, phospholyl), cyclooctatetraenyl, arene ligands, hydrocarbyls, and hydrides ligands. 

Through our studies of the above C-H activation reactions, we have found that we could do additional kinetic experiments to provide thermodynamic information on the stability of the various derivatives. These complexes all vary only in the hydrocarbyl group attached to rhodium - the spectator ligands are kept constant -so that relative bond strengths can be extracted from these studies. 

The sterically demanding Xp is able to stabilize heteroleptic Tm(II) complexes including the first hydrocarbyl-Tm(II) derivative [Tm(Tp ) (CHSiMe3)2] obtained by reaction of [Tm(Tp )I(THF)] with KCHoSiMe,. ... 

The general properties of peralkylcyclopentadienyl ligands are surveyed in Chapter 22. Protebly the most reactive actinide hydrocarbyls prepared to date are stabilized by bis(pentamethylcyclopentadienyl) (Cp ) co-ligation. These complexes can, in general, be prepared as shown below for a wide range of R and R groups [43-45] ... 

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