Clathrochelate precursor

The i/c=N values in IR spectra of the di- and hexachloride clathrochelate precursors are the lowest of all those known so far for clathrochelate iron(II) tris-dioximates. The vc=n bands of both types of dioximate fragments distinctly appeared in the case of partially substituted Cs-nonsymmetric complexes. Alongside the vm-o and vb-o bands of the macrobicyclic framework, the IR spectra of ribbed-functionalized clathrochelates also contained characteristic lines of the substituents in dioximate fragments [65, 68]. 

The structures of one clathrochelate precursor and two macrobicyclic ribbed-functionalized ruthenium(II) tris-dioximates were determined by X-ray analysis (Table 16). The Ru-N distances... 

The introduction of lipophilic substituents is of interest for producing surface-active compounds (surfactants) and liquid-crystal systems. The complexes with allyl substituents at the apical boron atoms are precursors for the synthesis of linear and netlike polymeric clathrochelates. 

The use of Route III presented problems because the attempts to obtain hexahalogenide precursors from initial dihalogendioximes by the standard procedures of synthesis of such clathrochelates have not been successful. Nevertheless, the conditions under which the yield of these complexes was 60-90 % were selected in Ref. 65 nitromethane was as a solvent, and acetonitrile FeAN4Cl2 solvato-complex as a source of Fe + ions, and the water was removed from the reaction mixture. The three hexachloride precursors with phenylboronic, re-butylboronic, and fluoroboronic capping groups (Scheme 13) were obtained [65]. 

Hexachloride precursors interacted with excess thiophenol in the presence of potassium carbonate under soft conditions to yield hexathiophenol clathrochelates (Scheme 13). 

The reaction of a n-butylboronic precursor with potassium phenolate led to the formation of hexaphenol Fe((C6H50)2Gm)3(Bre-C4H9)2 complex (Scheme 13). Attempts to obtain of the n- and t-butoxy-containing clathrochelates met with failure because of the destruction of precursors. 

The well-known synthetic procedures for crown ethers and their analogs allowed one to synthesize clathrochelates with dioximate fragments of the 0x0- and thioether crown type (Scheme 13). The interaction of phenylboronic and re-butylboronic precursors with 3 mols of the sodium salt of bis-(2-(o-oxyphenoxy))diethyl ether for 5 h in THF at 50-60° led largely to the formation of Ca-nonsymmetric tworibbed-substituted products (Scheme 13). The reactions of n-butylboronic precursor were studied in more detail. The use of a 30% excess of the sodium salt of bis-(2-(o-oxyphenoxy))diethyl ether and an increase in the reaction time up to 30 h permits one to isolate a tricrown ether clathrochelate (Scheme 13). Tetrabutylammonium salt ((re-C4H9)4N)Cl was used as an interphase catalyst for the... 

The template condensation of re-butylboronic precursor with 3,5-dithiaoctane-1,8-dithiol in the presence of CS2CO3 allowed to obtain in a low yield tris-(12-an-S4)-containing clathrochelate as a representative of a promising series of models of blue proteins [65]. 

The reaction of a phenylboronic precursor with an excess of n-butylamine unexpectedly led to the preferential formation of the tetrasubstituted clathrochelate by the modification of two of the three dichloroglyoximate fragments (Scheme 13). A similar product was also obtained in the case of cyclohexylamine. Attempts to obtain a hexa-M-butylamine clathrochelate were not successful. The interaction of precursors with aniline and its derivatives has resulted in the formation of a mixture of di- and trisubstituted products, which failed to be isolated as individual compounds [65]. 

The reactions of phenyl-, i-butyl- and fluoroboron-capped hexachloride iron(II) precursors with aliphatic amines proceeded under steady-state conditions of the solvent, temperature, and reaction time to produce clathrochelates of only one type irrespective of the nature of the substituent at the boron atom (Scheme 18). Therefore, the reactions of the phenylboronic Fe(Cl2Gm)3(BC6H5)2 precursor were studied. The reaction of precursor with n.-butylamine in DMF, benzene, THF, and /i-butylamine as the solvent led to the formation of only tetrasubstituted clathrochelate, whereas the reaction in chloroform unexpectedly resulted in trisubstituted clathrochelate, which underwent further functionalization in DMF with re-butylamine and cyclohexylamine but did not react with diethylamine (Scheme 18). 

The reaction of phenylboronic precursor with primary alicyclic cyclohexylamine in DMF and CHCI3 also led to the formation of tetra-and trisubstituted clathrochelates, respectively (Scheme 19). Trisubstituted clathrochelate underwent further functionalization in DMF with an excess of re-butylamine and aliphatic diamine (cadaverine). Thus, the overall reaction pathway in the previously mentioned reactions with primary sterically unhindered aliphatic amines involved a stepwise substitution in two of the three dichloroglyoximate fragments of hexachloride clathrochelates [69]. 

Dichloride FeBd2(C12Gm)(BF)2 precursor readily reacted with aliphatic primary amines of different natures in the DMF and THF to produce disubstituted clathrochelates (Scheme 22). The secondary amines react with dichloride precursor to substitute one of the two reactive chlorine atoms, and this permits one to obtain spacer-containing clathrochelate and bis-clathrochelate (Scheme 23). An alternative pathway for the synthesis of bis-clathrochelates uses... 

The nucleophilic substitution of the reactive chlorine atoms in hexa- and dichloride clathrochelates by a series of aliphatic amines is very sensitive to the effects of the medium (primary, the solvent employed), and the trend of the reaction is determined to a great extent by the donor properties of the amines and the steric accessibility of the nucleophilic centre. The subsequent substitution reaction course and feasible reaction products in the case of hexachloride precursors are presented in Scheme 24. The stepwise-formed clathrochelate complexes are denoted according to the degree of the substitution of chlorine atoms by amine groups ... 

The reactivity of partially substituted iron(II) clathrochelates is essentially dependent on the degree of substitution with primary sterically unhindered aliphatic amines in donor solvents. In the case of hexachloride precursors, a tetrasubstituted product is formed and is inert to further actions of amines. 

The reactions of nucleophilic substitution with participation of reactive clathrochelates are very sensitive to the donor properties of an attacking amine. With aromatic amines, as well as secondary and primary sterically hindered amines in acceptor solvents, and hexachloride precursors, the reaction stops with the formation of disubstituted products. When secondary and sterically hindered primary aliphatic amines are used in donor solvents and sterically unhindered primary aliphatic amines in acceptor solvents, the reaction terminates at trisubstituted products. In the case of sterically unhindered aliphatic amines, tetrasubstituted clathrochelates are formed. With dichloride precursor FeBd2(C12Gm)(BF)2, the primary aliphatic amines in donor solvents form diamine clathrochelates, whereas the secondary amines (diethylamine or piperazine) give only monoamine complexes both in acceptor and donor solvents. 

In the case of primary aliphatic amines, the reaction products are dramatically affected by the solvent employed. For instance, in the presence of solvents apt to produce a specific solvation of amines (chloroform, and an amine chlorohydrate solution in methylene dichloride), the reaction with hexachloride precursors terminates to yield the trisubstituted product DD D" formed via route A. At the same time, the use of some other solvents (such as benzene, 1,4-dioxane, THF, methylene dichloride, DMF, and alcohols, or the corresponding amine media) led to the formation of the sole tetrasubstituted product (DD"D"). In addition, in the case of sterically unhindered primary amines an alternative isomer (D D D") is not isolated, which indicates reaction route A and a specific control of the tie reaction in the transition state by solvation interactions and intramolecular hydrogen bonds. In the case of the dichloride FeBd2(C12Gm)(BF)2 precursor, with both primary (cyclohexylamine) and secondary (diethylamine and piperazine) aliphatic amines, only a monosubstituted product of the Bd2D type is formed in chloroform, whereas in some other solvents, a diamine clathrochelate of the Bd2D" type is obtained with both sterically hindered and unhindered primary aliphatic amines. 

The reaction of Ru(C12Gm)3(BC6H5)2 precursor with a 15% excess of re-butylamine (calculated from a tetrasubstituted clathrochelate) in DMF at 0°C for 2 h resulted solely in trisubstituted clathrochelate, and the substitution took place in two of the three dioximate fragments (Scheme 31). To produce tetrasubstituted product, a twofold excess of re-butylamine was used, and the reaction mixture was stirred for 10 h at room temperature. An unexpected result was obtained when DMF was replaced by chloroform the interaction of Ru(C12Gm)3(BC6H5)2 with re-butylamine both at room temperature and with a prolonged stirring at 50-r60°C yielded only one trisubstituted product [78],... 

As with iron(II) complexes, the di- and tricrown ether ruthenium (II) clathrochelates were isolated depending on the molar ratio precursor/salt of (bis-(2-(o-oxyphenoxy))diethyl ether and on the reaction time [78]. 

The apical functionalized oximehydrazonate clathrochelates were also obtained stepwise from initial semiclathrochelate precursors followed by H -catalyzed condensation with an excess of formaldehyde or TOF (Scheme 79) [67]. 

The temperature-dependent disorder of molecules in two or more positions is of interest with a view to the realization of structural phase transitions of the order-disorder type in crystals. Cs-symmetric clathrochelate complexes display a variety of specific features that favour the occurrence of temperature-dependent disorder. As an example, these specific features were examined in crystals of clathrochelate Fe(C12Gm)3(B i-C4H9)2 precursor [282]. The phase transition accompanied by the mechanical destruction of the... 

The Ev2 values for the clathrochelate complexes are more positive (by 70 mV) than those for the semiclathrochelate precursor, indicative of a stabilization of the cobalt(II) oxidation state relative to the cobalt(III) state on capping [129],... 

Monoribbed-functionalized Ca-nonsymmetric diamino- and dithioclathrochelates can be prepared starting from the dichloride precursor by Scheme 130. The complexing capabilities of such clathrochelates as cis-ligands should first be studied with respect to Pt2+ and Pd2+ ions. In this case, both 1 1 and 2 1 complexes can be isolated (Scheme 130). 

The hexachloride cobalt(II) tris-dioximates resulting from a direct template reaction have proved to be suitable precursors for the synthesis of triribbed-functionalized cobalt clathrochelates in different oxidation states. The reduction of these precursors can lead to the formation of cobalt(I) clathrochelates, the stability of which is accounted for by the effect of six acceptor chloride substituents in the clathrochelate framework. 

Ribbed-functionalized clathrochelates with a TAP geometry can be obtained starting from the tin-, germanium-, and antimony-capped chloride precursors (Scheme 133). 

A rigid dihydrazinophthalazine ligand may turn out to be a fairly selective precursor of binuclear clathrochelates (Scheme 140). 

A, A-[(en)2Co(III)-iLtNH2, M02-Co(III)(en)2] " with [Mo(V)204(l , S-pdta)] . They conclude that both steps contribute to the stereoselective course of the reaction. It is noteworthy also that A-[Co(III)(en)3f associates preferentially with A-[Co(III)(edta)] but that A-[Co(III)(en)3] is formed preferentially in the oxidation of [Co(II)(en)3] by A-[Co(III)(edta)] . Again, stereoselective contributions from precursor complexation and electron transfer steps are established. Sargeson and co-workers " note that stereoselectivities as high as 10% are suggested in reactions of cobalt clathrochelates. These are in accordance with other values. 

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