Metal organometallic complexes

The first ri -transition metal organometallic complexes 272 were made from Li(Mc4C4ESiMe3) (E = Si, Ge) and Cp HfC (98JA8245). Species 272 (E = Si) with trimethylphosphine forms the Hf-PMc3-adduct. 

B. Non-Metal and Non-Transition Metal Organometallic Complexes of Imidazoles. 120... 

It is well known that certain transition metal organometallic complexes, such as ferrocene, cymantrene (cyclopentadienylmanganese tricarbonyl) and butadieneiron tricarbonyl, and to a lesser extent, benzenechromium tricarbonyl, form organic derivatives and have an extensive derivative chemistry of their own. The parent complexes have already been discussed there follows a summary of the main features observed in the mass spectra of their organic derivatives (Table II, at the end of this section). 

Organomercurials are useful reagents for the synthesis of other organometallic complexes. Direct transmetallation is the most common approach and a large number of main group and transition metal organometallic complexes have been prepared in this way from organomercurials. 

Reactions of monochloro complexes of zirconium and hafnium stabilized by tripodal trianionic ligands (such as MeC(CH2NR)3 , HC(SiMe2NR)3 - and MeSi(SiMe2 NR)3 ) with the late transition metal organometallic complexes K[CpM(CO)2] (M = Fe, Ru) gives heterodinuclear complexes with unbridged metal-metal bonds. These het-erobimetallic complexes react with, for example, methyliso-cyanide to yield insertion products (Scheme 6). ... 

Chiefly through the work of Jonas and co-workers ( ) mixed-metal organometallic complexes also are known that involve interactions of lithium atoms with unsaturated r-bonded hydrocarbon ligands (olefin, cyclopentadienyl, arene, etc.). While reviews already are available 88, S9), we include examples for comparison purposes. The lithium complexes in this section show increasing complexity and diversity both in the geometries around the lithium atoms and in the degree and type of interactions involved. The common feature in these compounds is the interaction of a lithium atom with a hydrocarbon ligand which is n... 

Recent Developments in Theoretical Organometallic Chemistry. 15, I Redistribution Equilibria of Organometallic Compounds, 6, 171 Redistribution Reactions of Transition Metal Organometallic Complexes, 23, 9S Redistribution Reactions on Silicon Catalyzed by Transition Metal Complexes, 19, 213 Remarkable Features of (7] -Conjugated Diene) zirconocene and -hafnocene Complexes, 24, I Selectivity Control in Nickel-Catalyzed Olefln Oligomerization, 17, lOS Silyl. Germyl, and Stannyl Derivatives of Azenes. N H Part I. Derivatives of Diazene, N,H2, 23, 131... 

As with organoboranes, there are also several examples of transmetallation in which ligand insertion occurs to give stable transition-metal organometallic complexes ... 

Transition metal organometallic complexes like dicarbonyl cyclopentadienyl iron [128], tricarbonyl cyclopentadienyl manganese [129] and iron-arene complexes [130,131] have also been reported as photoinitiators for photochemical crosslinking of cyanate esters. Photosubstitution of carbonyl groups by -OCN during irradiation initiates the reaction in the former case whereas photochemical dissociation of arene triggers it in the latter system. 

After ferrocene, a large number of related molecules have been prepared—even some in which uranium is the metal. There is now an entire subset of transition-metal organometallic complexes known as metallocenes based on cyclopentadieifide ligands. These compounds are not only structurally interesting, but many of them have useful applications as catalysts for industrial processes. 

Alkaline earth metals NHj. pyridine and other Lewis base molecules Transition metals Organometallic complexes... 

Fluxional and Nonrigid Behavior of Transition Metal Organometallic -Complexes, 16, 211 Free Radicals in Organometallic Chemistry, 14, 345... 

Transition metal organometallic complexes, including ferrocenium salts and titanocene derivatives In conjunction with a co-initiator such as CCI4 Mn2(CO)io, Fe(CO)s, Cr(CO)6, W(CO)6, Mo(CO)6, Mo(CO)5Py, CpMn(CO)3... 

The present-day qualitative approach to the bonding in transition metal organometallic complexes is based on a combination of two models. The first, the 18-electron rule, has already been met in Chapter 2 (see Table 2.8)—iigands that bond to a transition metal in a low valence state normally do so in such a way that the metal atom is, formally, surrounded by 18-electrons . Of course with a few exceptions, the classical complexes of the Werner type and which are the subject of most of this book do not obey this rule, so that it is clear that much hinges on the low valence state requirement. Equally, the fact that most transition elements form neutral bis-fy -cyclopentadiene complexes, M(C5H5)2, shows that even for organometallic complexes of transition metals it is only an approximation. Many examples of molecules with more, and many examples with fewer, than 18 valence-shell electrons are known. Those with more tend to be readily oxidized, those with fewer tend either to be sterically hindered or readily add further ligands. 

Transition metal organometallic complexes containing bismuth are relatively rare. The dichlorobismuth complex [Fe(BiCl2)(CO)2Cp ] (Cp = q-C5H3Buy has been reacted with Na2[Fe(CO)4] to afford a nido cluster [Fe3 p3-BiFe(CO)2Cp (CO)9] (50) as an inseparable mixture with a Bi4 tetrahedral cluster [Bi4 p3-Fe(CO)3 3 Fe(CO)2Cp 2]. The open four-coordinate trianionic complex [Bi Fe(CO)4 4] has been investigated as a starting point for cluster... 

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