Alkyl and Aryl Compounds

It is a colourless gas which decomposes on heating above 420 K to give metallic tin, often deposited as a mirror, and hydrogen. It is a reducing agent and will reduce silver ions to silver and mercury(II) ions to mercury. SnSn bonding is unknown in hydrides but does exist in alkyl and aryl compounds, for example (CH3)3Sn-Sn(CH3)3. 

Cesium forms simple alkyl and aryl compounds that are similar to those of the other alkah metals (6). They are colorless, sohd, amorphous, nonvolatile, and insoluble, except by decomposition, in most solvents except diethylzinc. As a result of exceptional reactivity, cesium aryls should be effective in alkylations wherever other alkaline alkyls or Grignard reagents have failed (see Grignard reactions). Cesium reacts with hydrocarbons in which the activity of a C—H link is increased by attachment to the carbon atom of doubly linked or aromatic radicals. A brown, sohd addition product is formed when cesium reacts with ethylene, and a very reactive dark red powder, triphenylmethylcesium [76-83-5] (C H )2CCs, is formed by the reaction of cesium amalgam and a solution of triphenylmethyl chloride in anhydrous ether. 

Ruthenium and osmium form some remarkably stable alkyls and aryls compounds, often in unusually high oxidation states. 

The controlled hydrolysis of aluminum alkyl and aryl compounds yields oligomeric species of the formula (RA10) . They are called alumoxanes. Alkyl substituted alu-... 

Oxidative addition reactions to nickel(O) complexes are another well-developed synthetic method which affords mono and bis alkyl and aryl compounds (equation 148).1232-1239 The oxidative addition of a, ar -dichloro-p-xylene to [Ni(QjH4)(PPh3)2] gives the dinuclear nickel(II) complex t(PPh3)2ClNi(CH2C6H4CH2)NiCl(PPh3)2].124 ... 

In this chapter we will restrict our discussion of organometallic compounds to the alkyl and aryl compounds of magnesium and lithium, and the sodium and potassium salts of 1-alkynes. These substances normally are derived directly or indirectly from organohalogen compounds and are used very widely in organic synthesis. Organometallic compounds of transition metals and of boron are discussed in Chapters 11 and 31. 

Unsubstituted phosphino- and arsino-dithioformic acids and their dithioformates have not yet been described. In addition, the monosubstituted primary alkyl and aryl compounds have not been investigated very well. Disubstituted phosphinodithioformates can be prepared easily. Because of the difference in basicity of Ph2PH and Et2PH they react with CS2 in different ways (reactions 14 and 15). By addition of metal ions to the resulting ethyl compound, one CS2 is split off.1 Only the potassium complexes have a second CS2 molecule bonded to the phosphorus atom. 

Calcium has received some application in organic synthesis similar to that of magnesium alkyl and aryl compounds, CaRa, have been prepared, and it seems likely that many of the magnesium syntheses, already mentioned, could be accomplished by the use of calcium. 

Nd(C8H8)(OC4H8)][Nd(C8H8)2] Alkyl and aryl compounds R(C6H5)3 (R = Sc, Y)... 

Among the most important alkyl and aryl compounds are those in which the ligands CO, NO, NR, and O are also present. The carbonyl compounds CpRe(CO)3 and Cp Re(CO)3 are very important starting materials for much other chemistry and are made by the following reactions ... 

The most studied alkyl and aryl compounds are of the type Cp3AnR, An = Th, U, Np, and their Cp analogues. Unlike the d-block alkyls, decomposition by /3-H transfer and alkene elimination is not a major route but both thermal and photochemical pathways are multiple and complex. 

Some tr-alkyl and aryl compounds have been made with supporting ligands such as Cp, Cp, bulky aryloxides such as o -Bu QHjO,56 and tertiary phosphines, as exemplified by Cp UCH(SiMe3)257 and UR dmpe. Homoleptic compounds have proved more difficult to make. There are, however, the compounds Th(CH2Ph)4, ato complexes [Li tmed]3[MMe7], M = Th, U, and the blue U[CH(SiMe3)2]3 which is stable as the solid at -60°C though unstable in solution over a few hours.58... 

Perfluoroalkylcopper and perfluoroarylcopper compounds are noticeably more thermally stable than the corresponding alkyl and aryl compounds. Solutions of perfluoroalkylcopper compounds in DMSO or DMF are stable up to at least 120°C 200), whereas ether suspensions of alkylcopper compounds decompose at 0°C or below. Similarly, pure pentafluorophenylcopper tetramer decomposes at 210°C-220°C, and a sample has been kept in a Dry Ice chest for 5 years 32). However pure phenylcopper can be kept for no more than a few days, even under nitrogen 73). Solutions of pentafluorophenylcopper reagents containing metal halides in THF have been refluxed for 5 days or more without decomposition (97, 144). Other stable perhaloarylcopper reagents are those in which the aryl moiety is perfluoro(p-phenoxyphenyl) (96), pentachlorophenyl, and 2,3,5,6-tetrachloropyridyl 144), none of which... 

The synthesis of iridium(lll) alkyl and aryl compounds via nucleophilic displacement is straightforward starting from a suitable L3lrX3 complex with X most commonly being chloride. Chatt and Shaw carried out early work on the syntheses of iridium(III) alkyl complexes showing that fac[lrMe3(PR3)3] (69) could be formed by reaction between... 

The reactive and unstable alkyl and aryl compounds may be prepared at low temperatures from the alkyls and aryls of other metals as follows ... 

The possible role of oxygen atom transfer in molybdenum enzyme catalysis was recognized in the early 1970s (190-194). In the ensuing years, a wealth of chemistry has established molybdenum as the premier exponent of such reactions (7, 195). Importantly, related dioxo-Mo(VI) and oxo-Mo(IV) complexes are interconverted by oxygen atom transfer reactions (Eq. (13)). These reactions are effected by reductants (X) such as tertiary alkyl and aryl compounds of the group 15 elements (especially phosphines) and oxidants (XO) such as S- and N-oxides. In many cases, however, the Mo(VI) and Mo(IV) compounds participate in a comproportionation reaction yielding dinuclear Mo(V) complexes (Eq. (15)). 

Some simple alkyl and aryl compounds of metals in normal oxidation states can be considered as honorary coordination compounds. 

Caution. The lithium alkyl and aryl compounds and the resulting organolanthanides smolder in contact with air and react violently with water. A fire extinguisher should be ready to use nearby. 

Zinc. The salts used for the Zn reactions are the halides (chlorides, bromides and iodides) both alkyl and aryl compounds are used. Owing to the reactivity of organozinc compounds, air and moisture must be excluded from the reaction. Use of ether or dioxane, on evaporation of the solvent, leads to solvates RZnX-D (X = halide, D = Et20 or dioxane). The exchange between Et2Zn and Znl2 occurs slowly in ether at RT. 

There are a number of reports of the preparation of organotin compounds under Wurtz conditions, in which a mixture of the organic halide (RX) and tin halide is treated with metallic sodium (equation 4-19).24 This method can be used for both alkyl and aryl compounds, and involves the formation of RNa as an intermediate. However, the forma-... 

Where they are known, the organic compounds of Ca, Sr and Ba are highly ionic, reactive, and of little utility or importance. Magnesium compounds, of which the Grignard reagents are the best known, are probably the most widely used of all organometallic compounds. They are employed for the synthesis of alkyl and aryl compounds of other elements as well as for a host of organic syntheses. 

For the series sulphenamide, sulphinamide and sulphonamide, Hakkinen and Ruostesuo86 report the order of shielding, sulphenamide > sulphinamide > sulphonamide for alkyl and aryl compounds, whereas Dorie and Gouesnard115 reported sulphenamide > sulphonamide > sulphinamide for ClSO NR2 (n = 0-2). 

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