Insertion compounds types

Thermolysis of 12 with frans-cinnamaldehyde afforded the insertion compound 19, formed through the di-insertion of two carbonyl ligands into the C—Si bond of 12. The reaction of 12 with fumaronitrile yielded the cyclization product 20. X-ray study revealed 20 to be a cyclization product which contains two types of disilyl moieties, imino and N,N-bis(silyl)amino, which are connected by a five-membered ring. 

The term insertion compound is used for solids where atoms or ions enter a three-dimensional framework without disrupting its essential structure. Many oxide bronzes are of this type, based on transition metal oxides with inserted alkali or other electropositive metals. 

Although the study of sulfur dioxide-transition metal coordination chemistry is an area of relatively recent intensive pursuit, structural information now spans a large number of stereochemically distinct coordination situations. The types of M-SO2 binding which have been identified, excluding insertion compounds and compounds containing SO2 bridging metal centers, are shown in Fig. 1. Several examples of complexes containing each type... 

The second category is due to nonstoichiometric insertion compounds. Their formation can be written for an acceptor-type reaction as... 

The viologens are alkyl derivatives of the 4,4 -dipyridylium dication. The one- or two-electron reduction leads to a radical cation or a diamagnetic product, respectively [95]. This type of redox reaction has a good reversibility. In the phthalocyanines (PCs) and other 4-chelates, the nitrogen is also a component of the ring system. Donor-type Li" " insertion compounds of metal-free phthalocyanines were formed reversibly in LiC104/PC with up to six cations [96]. At the anode, copper phthalo-cyanine (CuPC) inserted reversibly y — 0.42 CIO4 anions/mol [97]. For copper tetraphenylporphyrin, y = 0.65 was found [98] (cf. Table 4). Composites of these... 

On mounting the electrodes to form the battery, the host lattice of the positive electrodes and the acceptor-type insertion compound of the negative electrode are employed. This corresponds to the discharged state, which is stable. The upper arrow corresponds to the first charge. On cycling, the anion migrates this time between the two electrodes (anion shuttle mechanism). 

The next group of materials comprises conducting polymers (ICP). Systems with identical polymers have often been reported for polyacetylene. It is known that this ICP forms insertion compounds of the A and D types (see Section 6.4, and No. 5 in Table 12). Cells of this Idnd were successfully cycled [277, 281-283]. However, the current efficiency was only 35% heavy losses were observed due to an overoxidation of the PA [284]. In other cases as for polypyrrole (PPy), the formation of D-PPy was anticipated but did not occur [557, 558]. Entry (6) in Table 12 represents some kind of ideal model. A PPy/PPy cell with alkyl or aryl sulfates or sulfonates rather than perchlorates is claimed in [559]. Similar results were obtained with symmetric polyaniline (PANI) cells [560, 561]. Symmetric PPy and RANI cells yield about 60% current efficiency, much more than with PA. An undoped PPy/A-doped PPy combination yields an anion-concentration cell [562, 563], in analogy to graphite [47], (cf. No. 7). The same principle can be applied with the PPy/PT combination [562, 563] (cf. No. 8). Kaneto et al. [564] have reported in an early paper the combination of two pol54hiophene (PT) thin layers (< 1 pm), but the chargeability was relatively poor (Fig. 40, and No. 9 in Table 12). A pronounced improvement was due to Gottesfeld et al. [342, 343, 562, 563], who employed poly[3-(4-fluoro-phenyl)thiophene], P-3-FPT, in combination with a stable salt electrolyte (but in acetonitrile cf. Fig. 40 and No. 10 in Table 12). In all practical cases, however, Es.th was below 100 Wh/kg. 

These inserted compounds 7.23-7.25 showed unexpected thermal stability so that no reaction performed to recover the modified palladium-free ligand led to clean products. However, the stability of these compounds is very much dependent upon the nature of the other ligands on the Pd atom. Thus, changing the chloride for an iodide led to a dramatic decrease in the thermal stability of the cyclopalladated compounds [82-84]. In reactions of this latter type, the total or partial dealkylation of the NMe2 group occurs to produce compound 7.26 or compound 121, respectively, as shown in Eq. (7.24). In a related reaction, it was possible to detect the presence of Mel together with an amount of CH4 [82]. 

This review has discussed only continuum-scale models. Other types of models are also used in the study of lithium batteries. Empirical models are used to predict battery life by extrapolating experimental results. Statistical mechanical mcxiels help in understanding transport on the molecular level and also in understanding thermodynamic properties of insertion compounds. For example,... 

Fig. 3.1 The types of insertion compounds as a function of the dimensionality. Red circles are intercalated ions across the host channels...

In the reaction of Q,/3-unsaturated ketones and esters, sometimes simple Michael-type addition (insertion and hydrogenolysis, or hydroarylation, and hydroalkenylation) of alkenes is observed[53,54]. For example, a simple addition product 56 to methyl vinyl ketone was obtained by the reaction of the heteroaromatic iodide 55[S5]. The corresponding bromide affords the usual insertion-elimination product. Saturated ketones are obtained cleanly by hydroarylation of o,/3l-unsaturated ketones with aryl halides in the presence of sodium formate, which hydrogenolyses the R—Pd—I intermediate to R— Pd—H[56]. Intramolecular hydroarylation is a useful reaction. The diiodide 57 reacts smoothly with sodium formate to give a model compound for the afla-toxin 58. (see Section 1.1.6)[57]. Use of triethylammonium formate and BU4NCI gives better results. 

In the presence of a double bond at a suitable position, the CO insertion is followed by alkene insertion. In the intramolecular reaction of 552, different products, 553 and 554, are obtained by the use of diflerent catalytic spe-cies[408,409]. Pd(dba)2 in the absence of Ph,P affords 554. PdCl2(Ph3P)3 affords the spiro p-keto ester 553. The carbonylation of o-methallylbenzyl chloride (555) produced the benzoannulated enol lactone 556 by CO, alkene. and CO insertions. In addition, the cyclobutanone derivative 558 was obtained as a byproduct via the cycloaddition of the ketene intermediate 557[4I0]. Another type of intramolecular enone formation is used for the formation of the heterocyclic compounds 559[4l I]. The carbonylation of the I-iodo-1,4-diene 560 produces the cyclopentenone 561 by CO. alkene. and CO insertions[409,4l2]. 

Pd-cataly2ed reactions of butadiene are different from those catalyzed by other transition metal complexes. Unlike Ni(0) catalysts, neither the well known cyclodimerization nor cyclotrimerization to form COD or CDT[1,2] takes place with Pd(0) catalysts. Pd(0) complexes catalyze two important reactions of conjugated dienes[3,4]. The first type is linear dimerization. The most characteristic and useful reaction of butadiene catalyzed by Pd(0) is dimerization with incorporation of nucleophiles. The bis-rr-allylpalladium complex 3 is believed to be an intermediate of 1,3,7-octatriene (7j and telomers 5 and 6[5,6]. The complex 3 is the resonance form of 2,5-divinylpalladacyclopentane (1) and pallada-3,7-cyclononadiene (2) formed by the oxidative cyclization of butadiene. The second reaction characteristic of Pd is the co-cyclization of butadiene with C = 0 bonds of aldehydes[7-9] and CO jlO] and C = N bonds of Schiff bases[ll] and isocyanate[12] to form the six-membered heterocyclic compounds 9 with two vinyl groups. The cyclization is explained by the insertion of these unsaturated bonds into the complex 1 to generate 8 and its reductive elimination to give 9. 

Among several propargylic derivatives, the propargylic carbonates 3 were found to be the most reactive and they have been used most extensively because of their high reactivity[2,2a]. The allenylpalladium methoxide 4, formed as an intermediate in catalytic reactions of the methyl propargylic carbonate 3, undergoes two types of transformations. One is substitution of cr-bonded Pd. which proceeds by either insertion or transmetallation. The insertion of an alkene, for example, into the Pd—C cr-bond and elimination of/i-hydrogen affords the allenyl compound 5 (1.2,4-triene). Alkene and CO insertions are typical. The substitution of Pd methoxide with hard carbon nucleophiles or terminal alkynes in the presence of Cul takes place via transmetallation to yield the allenyl compound 6. By these reactions, various allenyl derivatives can be prepared. 

The Bamford-Stevens decomposition of tosylhydrazones by base has been applied to steroids, although not extensively. It has been demonstrated that the reaction proceeds via a diazo compound which undergoes rapid decomposition. The course of this decomposition depends upon the conditions in proton-donating solvents the reaction has the characteristics of a process involving carbonium ions, and olefins are formed, often accompanied by Wagner-Meerwein-type rearrangement. In aprotic solvents the diazo compound appears to give carbene intermediates which form olefins and insertion products ... 

Electrodes that are prepared from acid-leached LT-LiCo, xNix02 compounds (0< x<0.2) show significantly enhanced electrochemical behavior over the parent LT-LiCo1 xNix02 structure. The improved performance has been attributed to the formation of compounds with a composition and cation arrangement close to the ideal Li[B2]04 spinel structure (B = Co, Ni) [62]. These spinel-type structures have cubic symmetry, which is maintained on lithiation the unit cells expand and contract by only 0.2 percent during lithium insertion and extraction. 

There is, however, another possible explanation. For relatively weak complexes, as in these cases, a complex other than one of the insertion type may form in solution, for example a charge-transfer complex. An early observation which may indicate the formation of other types of complexes was reported by Bartsch and Juri (1980), but not interpreted the dediazoniation rate for 4-tert-butylbenzenediazonium tetra-fluoroborate in 1,2-dichloroethane decreases by 12% in the presence of one equivalent of 15-crown-5, a host compound which does not form insertion complexes. Kuokkanen and Virtanen (1979) also observed some stabilization towards dediazoniation of 2-toluenediazonium ion by 18-crown-6, even though, for steric reasons, an insertion-type complex is hardly possible in this case. 

Kuokkanen (1986, 1987 a, 1991) supported the proposal of Nakazumi et al. (1983) based on kinetic and spectrophotometric comparisons of arenediazonium salt solutions in the presence of 18-crown-6 and pentaglyme. He also extended the systematic work on complex formation of benzenediazonium salts, substituted in the 2-position, and in the presence of 15-crown-5 (Kuokkanen, 1990 Kuokkanen et al, 1991). He discovered a useful way to differentiate between the two types of complexes in Scheme 11-2. Increasing the relative concentration of the host compound shifts the ultraviolet absorption band of both types of complex hypsochromically, whereas the NN stretching frequencies are significantly increased only in the case of insertion complexes. ... 

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