Tetrakis adduct formation

Cerium tetrakis(acetylacetonate), a venerable compound,695 exists as a and /3 modifications. Both these contain [Ce(acac)4] monomers of D2 square antiprismatic coordination but differ in the crystal packing. In the a form,696 Ce—0 = 2.36-2.43 A with the ring angle O—Ce— 0 = 72°, while in the / form697 Ce—0 = 2.32 A and O—Ce—0 = 71.3°. The tetrakis(acetyl-acetonates) of Zr, Hf, Th, U and Pu also show dimorphism. The tetrakis(dibenzoylmethanate) [Ce(dbm)4] adopts a similar square antiprismatic structure with Ce—O = 2.299-2.363 A and O—Ce—O = 70.8° or 71,2°.698 There is some tendency for Ce3+ /J-diketonates to pass into the Ce4+ tetrakis(/3-diketonate). A series of tri- and tetra-valent cerium /3-diketonates has been examined from the point of view of the effect of additional ligands such as Ph3PO on this process, and it was found that Ce3+ /J-diketonates were stabilized by adduct formation, particularly by 1,10-phenanthroline.699... 

The tetrakis complexes are easily obtained by the addition of an excess of the appropriate pyridine, in absolute ethanol or methanol, to a solution in the same solvent of the anhydrous nickel salt.147 The bis adducts are prepared by using stoichiometric amounts of the anhydrous reactants783 or by heating the corresponding tetrakis complexes at temperatures in the range 80-110 °C.784 820 Thermal decomposition of the bis and tetrakis adducts leads to the mono adducts. Using hydrated nickel salts as starting material may cause the formation of complexes with coordinated water molecules. 

Scheme 7-3 Topochemical solid-state synthesis of bis-adduct 17 [28] and templated formation of tetrakis-adduct 20 [29].

In order to increase the Lewis acidity of the indium centers in compounds such as 52, the preparation of derivatives that incorporate a tetrafluorophenylene backbone has also been pursued. l,2-Bis(halomercurio)tetrafluorobenzene (halide = chloride (53) or bromide (54)) reacts with two equivalents of the corresponding indium(I) halide in THF at 25 °C to afford the tetrakis(T i ) adduct of the respective 9,10-dihalo-9,10-dihydro-9,10-diinda-octafluoroanthracene (halide = chloride (55) or bromide (56)) (Scheme 22). Compound 56 is also prepared by the reaction of (o-C6F4Hg)3 (4) with InBr in refluxing toluene followed by treatment with THF. The formation of the diindacycles 55 and 56 in the reaction of 53 and 54 with two equivalents of the corresponding indium(I) halide is surprising since, in principle, bis(indiumdihalide) complexes would be the expected products. This cyclization... 

Ortiz AL, Echegoyen L (2010) Unexpected and selective formation of an (e, e, e, e)-tetrakis-[60]fullerene derivative via electrolytic retro-cyclopropanation of a D2h-hexakis-[60]fuller-ene adduct. J Mater Chem 21 1362-1364... 

Styrene and substituted styrenes react with tetramesityldisilene 1, tetra-tert-butyl-disilene 21, and tetrakis(tert-butyldimethylsilyl)disilene 22 to afford the corresponding disilacyclobutane derivatives.127,134 Similarly, [2 + 2] additions occur between the disilenes with a C = C double bond in an aromatic ring135 and acrylonitrile.136 Bains et al. have found that the reaction of disilene 1 with trans-styrene- provides a 7 3 diastereomeric mixture of [2 + 2] adducts, 201 and 202 [Eq. (95)] the ratio is changed, when czs-styrene-Ji is used.137 The formation of the two diastereomeric cyclic adducts is taken as the evidence for a stepwise mechanism via a diradical or dipolar intermediate for the addition, similar to the [2 + 2] cycloaddition of phenylacetylene to disilene ( )-3, which gives a 1 1 mixture of stereoiso-meric products.116,137... 

Reactions of this type are somewhat less satisfactory for preparation of mixed diboron derivatives containing boron-carbon bonds. Thus, while tetrakis(dimethylamino)diborane(4) is readily hydrolyzed to tetrahydroxy-diborane(4) in aqueous acid, l,2-bis(dimethylamino)-l,2-diethylborane(4) reacts with formation of hydrogen and cleavage of the boron-boron bond 14). Reaction of the dibutyl analog with a twofold excess of water gave the dimethylamine adduct of the boroxole... 

A tris(imidazolyl)borate (138) complex of thallium(I) has been synthesized.The solid-state structure of hydrotris(imidazolyl)boratothallium(I) consists of one-dimensional, twisted, ladderlike strands, and three-coordinate thallium centers. Due to the position of the nitrogen donors, the tris(imidazolyl)borate ligand is not capable of forming metal chelates as are observed in tris(pyrazolyl)borates. Poly(benzotriazolyl)borate ligands have some features of both tris(pyrazo-lyl)borate and tris(imidazolyl)borate systems. Thallium(I) complexes of bis-, tris-, and tetrakis (benzotriazolyl)borates are reported. These adducts have been synthesized by treating the corresponding potassium derivative with an equimolar quantity of thallium(I) formate. ... 

Intramolecular [3-I-2]-cycloaddition reactions have also been performed using alkyne moieties as reactants. An early example of this methodology is the high-yield formation of 27 from alkyne 26. As in the case of the (Z)-3-benzyloxybut-2-enoate derivatives (vide supra), the presence of the 3-siloxy group is essential for the reaction to proceed. A diastereomeric mixture of 26 leads to the formation of the two diastereomeric bicyclic adducts 27 in a combined yield of 88%. ° Interestingly, albeit with only 60 /o conversion after 100 hours, the same products are also formed at room temperature under the influence of ultrasound and 6 mol /o of tetrakis(triphenylphosphane)palladium(0) as catalyst. In a purely thermal reaction in the absence of a metal catalyst, a totally different reaction, presumably involving a Diels —Alder type addition of the alkyne to a vinylbenzene moiety, takes place. ... 

Cationic Tc(I)-hexakis(2-methoxy-isobutyl-isonitrile) tetrafluroroborate is labeled by reacting tetrakis(2-methoxy-isobutyl-isonitrile)-copper(I) tetrafluroroborate adduct with 99mrp pertechnetate, using the kit formulation. Heating the reaction vial in a boiling water bath further facilitates formation of Tc(I) sestamibi. 

Sugimoto, H., Tung, H.-C., Sawyer, D. T. (1988). Formation, characterization, and reactivity of the oxene adduct of [Tetrakis(2,6-dichlorophenyl)porphinato]iron(III) perchlorate in acetonitrile. Model for the reactive intermediate of cytochrome P-450,... 

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