X-Alkylation

Amine—borane adducts have the general formula R3N BX where R = H, alkyl, etc, and X = alkyl, H, halogen, etc. These compounds, characterized by a coordinate covalent bond between boron and nitrogen, form a class of reducing agents having a broad spectmm of reduction potentials (5). 

O-X Alkyl perchlorates. Chlorite salts. Halogen oxides, Hypohalites, Perchloric acid, Perchloryl Compounds... 

X = alkyl, H, halogen, etc. They are usually colourless, crystalline compounds with mp in the range 0-100° for X = H and 50-200° for X = halogen. Synthetic routes, and factors affecting the stability of the adducts have already been discussed (p. 165 and p. 198). In cases where diborane undergoes unsymmetrical cleavage (e.g. with NH3) alternative routes must be devised ... 

X. Alkyl groups usually have relatively little effect, and for convenience alkylamino compounds are included in the foregoing discussion of amino compounds. The acylamino (X = COR) and sulfon-amido (X = SO2R) derivatives are, however, treated separately. To some extent the tautomeric composition of these compounds can be predicted from a consideration of the properties of the analogous... 

Fig 1 Heteroatom-stabilised (X=OR, NR2) and non-heteroatom-stabilised (X=alkyl, aryl) alkyl- (1), alkenyl- (2), aryl- (3) and alkynylcarbene (4) complexes of group 6 metals... 

ROCOR" RNH ROAr" ROH ROR RH RNH2 RAr RR X X (anhydrides) X (aryl esters) X (carboxylic acids) X (alkyl esters) X (amides)... 

P-keto acid X = alkyl or aryl = ketone substituted malonic acid X=OH = substituted acetic acid... 

A number of stable heterobimetallic copper alkyne complexes have been reported, based on the strategy of using another metal bis(alkynyl) complex as a chelating ligand for copper. The 1,4-diyne [(r -CsFGSiMe Ti-(C=GSiMe3)2]180 (or related complex) was found to stabilize the copper units GuX, with X = alkyl,180,181 vinyl,180... 

Compounds of the type CpSnX3 (X = alkyl, Cp, Cl) are very photosensitive compared with alkyltin compounds, and on irradiation show strong E.S.R. spectra of the Cp-radical54. The equivalent silicon and germanium compounds do not show this reactivity (reaction 34). 

The mass spectra of trichlorophosphazenes C13P—NX (X = sulphamoyl, acyl, aryl, or alkyl) and cyclodiphosphazanes (C13PNX) (X = alkyl) have been described in detail.58... 

Substituent effects on the -(aminoethyl)cyclohexenone photochemistry were carried out to study the relative kinetic acidities of the tertiary aminium radical47. The ease of the methylene hydrogen to be removed as H+ increased in the order of X = alkyl < Si(CH3)3 < C=CH (equation 13). 

Figure 6.8 Relationship of enthalpy to log k values. Column, ODS silica, ERC-ODS, 15 cm x 6.0 mm i.d. eluent, 80% aqueous acetonitrile at 30 °C. Numbers beside symbols see Table 6.4. O, Polycyclic aromatic hydrocarbons x, alkyl-benzenes, O, halogenated benzenes A, alkanols and , alkanes.

Azidoborations of iminoboranes are smooth and facile reactions [Eq. (33a)] (14, 19). For X = alkyl, the azidoboration products cannot easily be distinguished from hypothetical alkyloboration products... 

Charge-transfer interactions have been observed between NbFj and MX4 (M = Si, Ge. or Sn. X = alkyl M = C, Si, or Sn, X = Cl) and several organic solvents, and for NbClj and TaClj with aromatic hydrocarbons and fluorocarbons. Tn these latter cases the enthalpies of interaction were estimated as 6.3 kJ mol The new complexes [MF L] (M = Nb or Ta, L = DMSO, EtCN, or CH CICN), [TaF, 2-Mepy)]. and [tap5(4-Mepy)2] have been prepared. Their vibrational spectra have been recorded and. together with those of [MF5(MeCN)] and [MFjLJ (M = Nb or Ta and L - DMSO or py), discussed in terms of MFjL and [MF L4][MFg] structures." ... 

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