Halides transition-metal complex anions

A variety of complexes of the thionyl imide anion [NSO] with both early and late transition-metal complexes have been prepared and structurally characterized. Since both ionic and covalent derivatives of this anion are readily prepared, e.g., K[NSO], McsMNSO (M = Si, Sn) or Hg(NSO)2, metathetical reactions of these reagents with transition-metal halide complexes represent the most general synthetic method for the preparation of these complexes (Eq. 7.10 and 7.11). ... 

Acidic chloroaluminate ionic liquids have already been described as both solvents and catalysts for reactions conventionally catalyzed by AICI3, such as catalytic Friedel-Crafts alkylation [35] or stoichiometric Friedel-Crafts acylation [36], in Section 5.1. In a very similar manner, Lewis-acidic transition metal complexes can form complex anions by reaction with organic halide salts. Seddon and co-workers, for example, patented a Friedel-Crafts acylation process based on an acidic chloro-ferrate ionic liquid catalyst [37]. 

Two commonly used synthetic methodologies for the synthesis of transition metal complexes with substituted cyclopentadienyl ligands are important. One is based on the functionalization at the ring periphery of Cp or Cp metal complexes and the other consists of the classical reaction of a suitable substituted cyclopentadienyl anion equivalent and a transition metal halide or carbonyl complex. However, a third strategy of creating a specifically substituted cyclopentadienyl ligand from smaller carbon units such as alkylidynes and alkynes within the coordination sphere is emerging and will probably find wider application [22]. 

Neutral carboranes and boranes react with transition-metal complexes forming metallocarboranes or metalloboranes, respectively. However, most metallocarboranes and metalloboranes are prepared from transition-metal halides and anionic carborane and borane species ( 6.5.3.4) or by reacting metal atoms and neutral boranes and carboranes. These reactions are oxidative addition reactions ( 6.5.3.3). 

The transition metal-group IV metal bond can be formed both by attack of a transition metal anion at a group IVg halide and by attack of an alkali metal derivative of the group IV element at a suitable transition metal complex. 

A more familiar example is Sn2 addition of an anionic nucleophile to an alkyl halide. In the gas phase, this occurs without activation energy, and the known barrier for the process in solution is a solvent effect (see discussion in Chapter 6). Finally, reactions of electron-deficient species, including transition-metal complexes, often occur with little or no energy barrier. Processes as hydroboration and 3-hydride elimination are likely candidates. 

When the sodium or bromomagnesium salts of these anions are treated with transition metal halides (FeCU) (78JOM(156)C33, 81IC3252) or carbonyls, e.g. Mn2(CO)10, very interesting 175 67r-phosphole transition metal complexes (89) and (90) are formed (equations 51 and 52) <79JCS(D)1552, 80JA994). 

The first successful syntheses utilizing trifluoromethyl iodide in transition metal chemistry were reported by Stone and his students. Stone reasoned that if CF3I would not react with transition metal anions to form trifluoromethyl derivatives [see Eq. (3)] then perhaps compounds containing perfluoroalkyl substituents could be generated by the oxidative addition of perfluoroalkyl halides to low valent transition metal substrates (9,10). The first reported trifluoromethyl-substi-tuted transition metal complex prepared by this route is shown in Eq. (4) (41). 

Transition metal complexes are cationic, neutral or anionic species in which a transition metal is coordinated by ligands. A classical or Werner complex is one formed by 2 metal in a positive oxidation state with donor ligands such as H20, NH3, or halide ions. 

Phosphines and their derivatives are known to be very useful ligands toward transition metals and a variety of complexes with phosphine as a ligand have been prepared for all kinds of transition metals. If one of the substituents on a coordinating tertiary phosphorus compound is abstracted as an anion, it would form a cationic phosphenium complex. Actually this strategy has been widely used, and halide, hydride, and alkoxide have been abstracted as an anion by an appropriate Lewis acid. An alternative method to prepare cationic phosphenium complexes is a direct reaction of a phosphenium cation with a transition metal complex having appropriate... 

One-electron oxidations can give stable ty -ff-metal-carbon bonds accompanied by loss of donor ligand. The reactions, which proceed according to Eq. (e), arc not presented here unless formation of an > -T-metal-carbon bond with the carbon of RX is established. One-electron oxidation can often compete with the two-electron oxidative addition with coupled alkyl cis coproducts. The reaction of an anionic transition-metal complex with an organic halide is an oxidative addition ... 

Formation of Carbon-Transition and Inner Transition Metal Bond 121 5.8.2.9. from Organic Halides, Tosylates and Acetates 5.8.2 9.2. by Reaction with Metal-Complex Anions... 

Heterobimetallic complexes have recently attracted considerable attention in light of the promise of enhanced reactivity as a result of the cooperativity between adjacent, but electronically different, metal centers. A large number of these bimetallic compounds have been synthesized by the reactions of organometallic halides with anionic metal carbonyls. Here, we describe an extension of this route to the synthesis of hydride rich. Os—Zr and Os—Rh complexes by the reaction of organometallic halides with a metal poly hydride anion. These preparations demonstrate the synthetic utility of transition metal polyhydride anions. 

Ionic liquids with anions containing transition metal complexes were among the earliest developed room temperature ionic liquids [60], Transition metal based ionic liquids have been synthesized either by reaction of phosphonium or imidazolium halides with the corresponding metal halides, or by metathesis with alkali salts of the metal-based anions. Among the metal containing ionic liquids, ionic liquid-crystals are excluded in this section as they were reviewed thoroughly in 2005 [61], Synthesis of metal based salts can be divided in to three groups (1) transition metal salts, (2) p-block metal salts and (3)/-block metal salts. 

Electrophilic activation and hydrolysis of a-CF bonds in transition metal complexes is well precedented with strong Lewis or protic acids (Sect. 2.2). Abstraction of halide using AgBF4 in moist dichloromethane from the perfluor-obenzyl and perfluoropropyl complexes 1 and 2 affords the cationic aqua complexes 3+ and 4+ which exist as hydrogen bonded dimers in the solid state with tetrafluoroborate anions bridging the coordinated aqua ligands [69] (Scheme 4). 

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