Silver complexes alkoxides

A few years earlier, Herrmann et al. published a carboxylic ester functionalised imi-dazolium salt that was synthesised directly from imidazole and bromoacetic acid ethyl ester [216]. Owing to its method of synthesis the imidazolium salt is C -symmetric with two ester functional wingUp groups. Generation of the rhodium(I) and palladium(II) carbene complexes was realised by reaction of the imidazolium salt with a rhodium alkoxide precursor or with palladium(II) acetate in the presence of NaOEt and Nal (see Figure 3.76). The silver(I) oxide method had not been discussed in the literature at the time [11]. 

Carboxylate complexes are often synthesized by refluxing the acid with the metal salts (such as carbonate, sulfate, oxide, etc.), or by reaction of the sodium or silver salt of the acid with the metal halide. Insertion of CO2 into a-bonded organotransition metal species has also been used to generate carboxylate complexes, as has exchange reactions with metal alkoxides (see Section 3.3). 

Only a few complexes containing Ce(IV)-carbon bonds have been structurally characterized so far. Salt metathesis reactions utilizing mixed alkoxide nitrate Ce(IV) precursors [Eq. (63)] [311], as well as the oxidative salt elimination of K[Ce(COT)]2 ate complexes with silver iodide, led to isolable organocerium(IV) species [Eq. (64)] [80e]. The oxidation of the homoleptic Ce(III) alkoxide Ce(OCrBu3)3 with benzoquinone yielded a dinuclear heteroleptic Ce(IV) complex [Eq. (65)] [312]. 

Following the well-known Pinner synthesis of imidates by the reaction of nitriles with alcohols, there has been considerable interest in recent years in treating a nitrile bond within the coordination sphere of metal ions with water or alcohols. It has been suggested that the initial step consists of nucleophilic attack of an external or coordinated hydroxide or alkoxide anion on the nitrile carbon atom. A number of imidate complexes have been isolated from the reactions of 2-cyanopyridine with metal [Cu", Ni , Co" and Fe"] salts in alcohols, of frans-PtMeClL with pentafluorobenzonitrile and silver hexafluorophosphate in alcohols," and of o-cyanobenzylplati-num complexes. "... 

The molybdenum neopentyUdene complex Mo(CHBu )(NR)(OBu )2 is the active catalyst used in a fascinating development for the synthesis of 11-Vt semiconductor clusters (ZnS, CdS, PbS) and silver and gold nanoclusters of predictable size within microdomains in films of block copolymers prepared by ROMP. Block copolymers of norbomene and a functionalized norbomene that wiU complex with a metal-containing compound were prepared and characterized as monodisperse materials. The functionalized component (amine, alkoxide, or thiolate) then sequestered the metal and the metallated block copolymer was cast into a film which was subsequently treated with H2S to convert the metal into the sulfide. The molybdenum complexes have also featured in the development of the synthesis of side-chain liquid crystal polymers by living ROMP.98 99... 

Interest in the synthesis and structural characterisation of less common metalloorganophosphide systems has continued. A range of alkali metal complexes of the phosphide anion (48) has been prepared from the lithio-phosphide by simple metathesis with alkali metal alkoxides. The lithio-phosphide exists as a dimer, but crystallisation of the sodium and potassium drivatives in the presence of TMEDA results in the formation of monomeric species. The caesium triphosphenide (49), involving a phosphorus analogue of the allyl anion, has been prepared from the previously described sodium complex. Unlike the sodium and potassium complexes, which are monomeric, the caesium complex has a polymeric structure. A variety of arylphosphide complexes of magnesium, calcium, strontium and barium have been prepared and their solid state structures characterised. Cop-per(I)-, silver(I)- and gold(I)-complexes of the cyclo-(P ion have also... 

---