Bis metal complexes

Although diphosphine disulfides of formula R2P(S)P(S)R2 take up a trans conformation in the solid state (see Section 5.2.3), upon coordination to a metal centre they can rearrange to adopt a cis conformation, hence facilitating bidentate chelation of the metal (e.g., Equation 78).117 In addition, a cis-bridging mode has also been proposed for these ligands in bi-metallic complexes.117... 

As representatives of this class of compounds, one hindered and one non-hindered gem-boriozirconocene alkene were prepared [54]. Hydrozirconation of a 1-alkynyldioxaborolane with Cp2Zr(H)Cl in either 1,4-dioxane or THF proceeded readily by a syn addition to give the essentially pure ( )-l,l-bis-metallic boriozirconocene 45 [12]. This bis-metallic complex 45 was also reacted with various electrophiles, thereby generating the alkenylboron derivatives 53—57 as shown in Scheme 7.17. 

We have now constructed the missing ligands needed to prepare the other possible isomers of the dinuclear cyclometallates (Figure 25). Each of these compounds forms bis-metallated complexes [(tpy)Ru(L)Ru(tpy)]2+ which are generally similar to the isomeric compounds with CNs donor sets at each end. However, they exhibit a single ruthenium(n)/(ni) redox process at +0.15 V. 

Quite recently we also succeeded in X-ray structure determination of the mono-metallated complex of 1 with (Cp Ru)+ [64]. As in the bis-ruthenium analog the metal was 7 coordinated to one of the benzene rings of 1 on its exo (convex) face. This is the first experimental evidence demonstrating the exo preference of 7 coordination of (Cp Ru)+ to corannulene. Also, another bis-metallated complex, [(Cp Ru)2( 2 / / C2oHio)][SbF6]2 was prepared and characterized by X-ray [64]. 

Recent structural studies of squaric acid have shown it to form 1,3-bis(metal) complexes as well as 1,2-bidentate chelates with Ce(III) or with Cu(II). Stopped flow methods have been used to study the reaction between squaric acid and Fe(III). In solutions with [H ] <0.02 M, biphasic absorbance changes are observed due to operation of a number of parallel and series pathways. The initial reactions are complexations to form a 1 1 compound, [Fe(III)(H20)5(squarate)] , and a 2 1 compound, [Fe(III)2(0H)2(H20)6(squarate)] these are followed by a slower reaction leading to the reduction of Fe(III) to Fe(II) by the ligand. The reaction scheme, shown in Eq. (19)-(21), involves monomeric and dimeric squarate... 

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. 

Metallacycle fomiation has also been observed in bis-Cp complexes. Heating Cp 2UR[P(Si(CH2)2)2] (R = Cl [146840-37-17, CH [146840-39-3]) results in the metaHation of the phosphido ligand. These complexes are stmcturaHy similar to the group 4 and 6 transition-metal metallacycle complexes, but show a dramatically reduced reactivity. 

Direct Blue 218 had reported sales of 623 t valued at 4.4 million ia 1987. It is produced from Direct Blue 15 (76) by metallizing and elimination of methyl groups from the methoxide to form the copper complex. Direct Blue 15 (76) is prepared by coupling o-dianisidine [119-90-4] to two moles of H-acid (4-amiQO-5-hydroxy-2,7-naphthalenedisulfonic acid) under alkaline pH conditions. Other important direct blues iaclude Direct Blue 80 (74), (9-dianisidine coupled to two moles of R-acid (3-hydroxy-2,7-naphthalenedisulfonic acid [148-75-4]) followed by metallizing to form a bis copper complex, and Direct Blue 22 (77), an asymmetrical disazo dye, prepared by coupling o-dianisidine to Chicago acid [82-47-3] and 2-naphthol. Direct Blue 75 (78) is an example of a trisazo dye represented as metanilic acid — 1,6-Q.eve s acid — 1,6-Q.eve s acid — (alb) Ai-phenyl J-acid. 

Bismuth heterocycles, 1, 539-561 Bismuthiol I metal complexes, 6, 565 IR spectra, 6, 552 ring structure, 6, 561 structure, 6, 557 Bismuthiol II metal complexes, 6, 565 IR spectra, 6, 552 Bisnorisopenicillin, 7, 332, 333 Bisnorpenicillin V, 7, 331 Bis( l,3,4-oxathiazol-2-ones) applications, 6, 945 Bisoxiranes synthesis, 7, 42 Bi(spiroisoxazolines) synthesis, 6, 108 Bi(spirophosphoranes) polytopal rearrangements, 1, 529 reactions, 1, 535 Bispyranones synthesis, 3, 793 a,oj-Bispyranones, alkylene-irradiation, 3, 678... 

Cryptands, 7, 731-761 alkali metal complexes NMR, 7, 740 reactivity, 7, 743-744 alkaline earth complexes reactivity, 7, 743-744 anion complexes, 7, 747-748 applications, 7, 753-761 as biological models, 7, 753-754 bis-tren... 

Bis ( -arene) metal complexes have been made for many transition metals by the AI/AICI3 reduction method and cationic species [M( j -Ar)2]"" " are also well established for n = 1, 2, and 3. Numerous arenas besides benzene have been used, the next most common being l,3,5-Mc3C6H3 (mesitylene) and CeMce. Reaction of arenas with metal carbonyls in high-boiling solvents or under the influence of ultraviolet light results in the displacement of 3CO and the formation of arena-metal carbonyls ... 

To examine potentiality of other ylides and their metal complex containing Sb, As, P, Bi, and Se as new novel initiator in polymer synthesis via living radical polymerization. 

Xylenolorange. This indicator is 3,3 -bis[ IV,/V-di(carboxy methyl Jaminomethyl]-o-cresolsulphonphthalein it retains the acid-base properties of cresol red and displays metal indicator properties even in acid solution (pH = 3-5). Acidic solutions of the indicator are coloured lemon-yellow and those of the metal complexes intensely red. 

Attempts have been made to catalyze the arrangement of 3-oxaquadricyclane to oxepins with transition-metal complexes.1 32 1 35 When dimethyl 2,4-dimethyl-3-oxaquadricyclane-l,5-dicarboxylate is treated with bis(benzonitrile)dichloroplatinum(II) or dicarbonylrhodium chloride dimer, an oxepin with a substitution pattern different from that following thermolysis is obtained as the main product. Instead of dimethyl 2,7-dimethyloxepin-4,5-dicarboxylate, the product of the thermal isomerization, dimethyl 2,5-dimethyloxepin-3,4-dicarboxylate (12), is formed due to the cleavage of a C O bond. This transition metal catalyzed cleavage accounts also for the formation of a 6-hydroxyfulvene [(cyclopentadienylidene)methanol] derivative (10-15%) and a substituted phenol (2-6%) as minor products.135 The proportion of reaction products is dependent on solvent, catalyst, and temperature. 

Bis(phthalocyanines) are also accessible by the reaction of isoindolinediimine and suitable metal compounds. For example, zirconium(IV) chloride when treated with isoindolinediimine in refluxing quinoline under a nitrogen atmosphere for 2 hours gives a zirconium(IV) bis(phthalocyanine) complex. 

Some bis(dinitrogen) complexes exist, generally as m-isomers (presumably this minimizes competition for the metal t2g electron density in 7r-bonding). Unlike ruthenium, osmium(III) dinitrogen complexes do exist, showing osmium(III) to be a better 7r-donor not surprisingly, they are more labile than the osmium(II) species. 

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