C=N compounds

This type of isomerism is also possible with other double bonds, such as C=N, N=N, or even C=S, though in these cases only two or three groups are connected to the double-bond atoms. In the case of imines, oximes, and other C=N compounds, if W = Y 60 may be called syn and 61 anti, though ( ) and (Z) are often used here too. In azo compounds there is no ambiguity. Compound 62 is always syn or (Z) regardless of the nature of W and Y, and 63 is E. 

Hydrolysis of imines, oximes, hydrazones, or other C=N compounds... 

A surprising variety of calcium compounds with combinations of mixed B, C or N anions is known, with some of them listed in Table 8.1. Their structures may contain anionic networks, or very often, triatomic anions with 16 valence electrons, and other anionic species. Some examples of Ca-(B,C,N) compounds are displayed in Fig. 8.1, and will be briefly discussed here. 

Fig. 8.1 Crystal structures of some calcium-(B,C,N) compounds (a) CaBe (LaBg type) (b) CaB4 xCx (LaB4 type) (c) CaB2C2 (corresponding with LaB2C2) (d) Can(CN2)2N6 (e) Ca3(BN2)N (f) Ca3Cl2C3 (g) Ca3Cl2(CBN).

S.2 Problems and Pilfalls of some Calcium Compounds with (mixed) B,C,N Anions 123 Table 8.1 Some Ca-(B,C,N) and Ca-CI-(B,C,N) compounds. 

I 8 Current State on (B,C,N) Compounds of Calcium and Lanthanum Energy... 

Mixed B-C-N compounds of lanthanum maybe subdivided into La-(BNx), La-(BCx), and La-(CNx) compounds (Fig. 8.15). The chemistry of lanthanide nitridoborates has been developed in some detail and some properties were studied. But still more work is necessary, especially in the field of quaternary Ln-metal-(BNx) compounds. 

As a defined ternary B-C-N compound is not known, other starting materials are to be considered in order to synthesize one of the, yet unknown, La-B-C-N compounds. Solution chemistry routes were successfully performed with tetra-cyanoborates to synthesize the compounds A[B(CN)4] with monovalent A = Li, Ag, Cu cations, and M[B(CN)4]2 with divalent M = Hg, Cu, Zn, Mn cations [47]. 

Cubic BC2N. Hetero-diamond B C—N compounds have recently received a great interest because of their possible applications as mechanical and optical devices. The similar properties and structures of carbon and boron nitrides (graphite and hexagonal BN, diamond, and cubic BN) suggested the possible synthesis of dense compounds with all the three elements. Such new materials are expected to combine the best properties of diamond (hardness) and of c-BN (thermal stability and chemical inertness). Several low-density hexagonal phases of B,C, and N have been synthesized [534] while with respect to the high-density phases, different authors report contradictory data [535-538], but the final products are probably solid mixtures of c-BN and dispersed diamonds [539]. 

The applications of sodium acyloxyborohydrides, formed from sodium borohydrides in carboxylic acid media, are reviewed. ° Useful reviews of the stereoselective reduction of endocyclic C=N compounds and of the enantioselective reduction of ketones have appeared. ... 

Only a few examples of the [3 + 2] cycloaddition of thiocarbonyl ylides with C=N compounds have been reported so far. By comparison with aldehydes, imines are poor dipolarophiles. For example, Al-benzylidene methylamine and adamanta-nethione (5)-methylide (52) produce 1,3-thiazolidine (129) in only 13% yield (163). An alternative and efficient approach to 1,3-thiazohdines involves the [3 + 2] cycloaddition of azomethine ylides with thiocarbonyl compounds [cf. (169)]. 

Our laboratory conducted the most extensive investigation of the 2,3,1-benzodiazaborines reported to date. We analyzed 25, l,2-dihydro-l-hydroxy-2,3,l-benzodiazaborine (26), and certain derivatives related to 26 by multisolvent H, C, "B, and NMR using isotopically-enriched ( C, N) compounds <97JA7817>. The X-ray crystal structures of 25 and 26 were obtained first, and that of the 2-methyl derivative 39 was determined soon thereafter <98AX(C)71>. The topography (internal geometry, intramolecular associations) of 39 was found to be most similar to 26, but some subtle 25-like characteristics were found. All three boron heterocycles were shown to exist in planar form in protic solution just like they do in the... 

A wide variety of compounds having the primary amino group condense with carbonyl compounds to give )C=N— compounds by the elimination of water. The latter reactions are usually acid catalyzed because protonation of the carbonyl group enhances its reactivity toward nucleophilic attack by the amino group on the carbonyl carbon atom (Eq. 1). 

The Addition of Organometallic Compounds to C=N Compounds /V-Hydro-C-alkyl-addition... 

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