Organometallic anion chemistry

R. A. Sawicki, Triphase Catalysis in Organometallic Anion Chemistry, in Phase Transfer Catalysis New Chemistry Catalysts, and Applications (Ed. Ch. M. Starks), ACS Symposium Ser. No. 326, American Chemical Society, Washington, DC, USA, 1987, Chapter 12, p. 143. 

Those ligands with N, O, P and S donors, as well as the halogen anions, are particularly common. These donor atoms cover the large majority of ligands you are ever likely to meet, including in natural biomolecules. There are others, of course even carbon, as II3C, for example, is an effective donor, and there is an area of coordination chemistry (organometallic chemistry) devoted to compounds that include M—C bonds, addressed later in Section 2.5. 

He X, Hartwig JF. Boryls bound to iron carbonyl. Stmcture of a rare bis(boryl) complex, synthesis of the first anionic boryl, and reaction chemistry that includes the synthetic equivalent of horyl anion transfer. Organometallics. 1996 15 400-407. 

As a result of the systematic application of coordination-chemistry principles, dozens of previously unsuspected stnicture types have been synthesized in which polyhedral boranes or their anions can be considered to act as ligands which donate electron density to metal centres, thereby forming novel metallaboranc elusters, ". Some 40 metals have been found to act as acceptors in this way (see also p. 178). The ideas have been particularly helpful m emphasizing the close interconnection between several previously separated branches of chemistry, notably boron hydride clu.ster chemistry, metallaboranc and metallacarbaborane chemistry (pp. 189-95). organometallic chemistry and metal-metal cluster chemistry. All are now seen to be parts of a coherent whole. 

Structural types for organometallic rhodium and iridium porphyrins mostly comprise five- or six-coordinate complexes (Por)M(R) or (Por)M(R)(L), where R is a (T-bonded alkyl, aryl, or other organic fragment, and Lisa neutral donor. Most examples contain rhodium, and the chemistry of the corresponding iridium porphyrins is much more scarce. The classical methods of preparation of these complexes involves either reaction of Rh(III) halides Rh(Por)X with organolithium or Grignard reagents, or reaction of Rh(I) anions [Rh(Por)] with alkyl or aryl halides. In this sense the chemistry parallels that of iron and cobalt porphyrins. 

Novel anionic gold(I) and gold(III) organocomplexes. Journal of Organometallic Chemistry, 131(3), 471 75. 

Grigg, R. Sridharan, V. (1999) Palladium Catalyzed Cascade Cyclisation - anion Capture, Relay Switches and Molecular Queues. Journal of Organometallic Chemistry, 576, 65-87. 

No attempt to cover the coordination chemistry of unsaturated cyclic anions such as cyclopentadienyl is made here, due to their coverage in the companion series on Comprehensive Organometallic Chemistry. The only example to be mentioned here, because it is the first example of a high-spin Co11 organometallic complex, is Co(Cp)(Tp).196... 

The chemistry of coordination compounds comprises an area of chemistry that spans the entire spectrum from theoretical work on bonding to the synthesis of organometallic compounds. The essential feature of coordination compounds is that they involve coordinate bonds between Lewis acids and bases. Metal atoms or ions function as the Lewis acids, and the range of Lewis bases (electron pair donors) can include almost any species that has one or more unshared pairs of electrons. Electron pair donors include neutral molecules such as H20, NH3, CO, phosphines, pyridine, N2, 02, H2, and ethyl-enediamine, (H2NCH2CH2NH2). Most anions, such as OH-, Cl-, C2042-, and 11, contain unshared pairs of electrons that can be donated to Lewis acids to form coordinate bonds. The scope of coordination chemistry is indeed very broad and interdisciplinary. 

Alkenes frequently have two kinds of C—H bonds, vinyl and allyl, that are generally more acidic than the C—H bonds of saturated alkanes. Quantitative measures of acidity are related to the chemistry of the corresponding carbanions and carbanion salts or organometallic compounds. Several methods have been used for the study of anions in the gas phase1. For many acids it is possible to measure equilibrium constants for equilibria of the type in equation 1. From such equilibrium constants with compounds RH of independently known gas-phase acidity, it has been possible to determine the acidities of a wide range of compounds2. 

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