Cationic adducts nitrogen bases

The XeF+ cation forms Lewis acid—base adduct cations containing N—Xe—F linkages with nitrogen bases that are resistant to oxidation by the strongly oxidizing XeF+ cation having an estimated electron affinity of the XeF+ cation of 10.9 eV (12). The thermally unstable colorless salt,... 

The [4-1-3] cycloaddition between 2-aminofuran and oxyallyl cations, followed by base-induced elimination of the resulting adducts, was used in the synthesis of 3-aminotropones <05TL8475>. A chiral Lewis acid-catalyzed [4t-3] cycloaddition between furans and nitrogen-stabilized oxyallyl cations derived from allenamides was developed. As depicted below, the Cj-symmetric salen-based ligand is the most effective in promoting this asymmetric cycloaddition reaction <05JA50>. 

The deprotonation step, either by the sensitizer radical anion or by some adventitious base, is essential for the formation of any amine derived products. This step can be prevented if the a-hydrogens are arranged in a plane orthogonal to the singly occupied nitrogen n-orbital a requirement which is met for the radical cation of l,4-diazabicyclo[2.2.2]octane (DABCO). The low oxidation potential, due to the interaction of the pair of transannular nitrogens, makes this an excellent electron transfer quencher. Yet, no product formation is observed as a result of these interactions, with the possible exception of the zwitterionic adducts formed with highly electrophilic ketones [193]. 

As noted previously, the formation of approximately tetrahedral bonds to nitrogen occurs principally in ammonium cations (R,N+), amine oxides (R3N+—O"), and Lewis add-base adducts (e.g., R3N+—B X3). In the amine oxides and these adducts, the bonds must have considerable polarity in the amine oxides, for instance, N — O donation cannot be effectively counterbalanced by any back-donation to N. In accord with this, the stability of amine oxides decreases as the R3N basidty decreases, since the ability of N to donate to O is the major factor. Similarly, R3N —> BX3 complexes have stabilities that are roughly parallel to R3N basicity for given BX3. When R is fluorine, basicity is minimal and F3N —> BX3 compounds are unknown. It is, therefore, curious that F3NO is an isolable compound. Evidently the extreme electronegativity of fluorine coupled with the availability otpir electrons on oxygen allows the structures in (9-V) to contribute to stability. 

A series of 1 1 adducts of imidobis(sulphuryl chloride) and some Lewis bases has been prepared. Conductivities and i.r. data revealed that the nitrogen atom of the bases is co-ordinated to the labile hydrogen atom of the imidobis(sulphuryl chloride), giving a N—bonded cation and the [N(S02C1)2] anion. I.r. and Raman spectra have been recorded for liquid Me0S02Cl as well as the i.r. spectra of the vapour and of solutions in CCI4. With the exception of the two torsional modes, all fundamentals were observed and assigned on the basis of Q symmetry. ... 

Reactions in RC Ionization is initiated by formation of alkah-metal ions on the emitter. A successful method for obtaining lithium ion cationization mass spectra must provide a means for binding hthium ion to the sample molecules. Lithium ions can be injected into an inert gas, such as nitrogen, that contains a trace amormt of sample, and (M + Li)+ complexes are formed by termolecnlar association reactions. The ionic products observed are a reflection of association reaction rates. The formation of an adduct ion is commonly assumed to be a three-body process, in which a neutral molecule collides with an ion-molecule complex and removes an amormt of energy, stabilizing the (M + Li)+ complex. Based on this model, the cationization process would be suitable in a high-pressure environment, since the added gas molecules serve as the third body in the analyte addition reaction with alkali-metal ions. 

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