Mononuclear derivatives

Although not presented specifically as a potential synthesis of mononuclear derivatives, the ready conversion of cyanocarbon sulfides (19) into condensed ring isothiazoles (20) is of interest and may provide new approaches to simpler isothiazoles. ... 

The coordination chemistry of tertiary phosphine-functionalized calix[4]arenes have been described.279 Treatment of a bis(diphenylphosphino) or bis(dimethylphosphino) derivative of calix[4]arene with [PtCl2(COD)] leads to the formation of the corresponding dichloroplatinum(II) complex. The related diplatinum(II) species has also been reported with the tetrafunctionalized calix[4]arene.280 The mononuclear derivative is susceptible to oligomerization if the two free phosphine ligands are not oxidized or complexed to another metal center such as gold(I).279 The platinum(II) coordination chemistry of a mono-281 and diphosphite282 derived calix[ ]arene (n = 4 and 6, respectively) has also been described. 

Organolithium reagents stabilized by ct-silyl groups have been recently used for the synthesis of mononuclear derivatives such as compounds 8, 9 which the bulky (PhMe2Si>3C and (Me3Si>3C as ligands directly attached to the mercury center.30 Other examples include the dialkylmercury products shown in Equations (2) and (3).31 32... 

As already shown in Eqs. (3), (4) and (5), fragmentation of carbonyl cluster anions, on reaction with carbon monoxide becomes easier with increasing negative charge. It is therefore not surprising that reduction of tetranuclear clusters with alkali metals in excess, gives rise to simple mononuclear derivatives [M(CO)4]-, as found for Co4(CO)12 in liquid NH3 13, e Rh4(CO)12 in THF under C056) and Ir4(CO)12 in THF under CO 17S ... 

In this chapter we have tried to give a general presentation of the most efficient synthetic routes, the main characteristic structural features and a discussion of the reactivity patterns. Special attention is devoted to the chemistry of mononuclear derivatives containing linear allenylidene groups as they are most frequently the active species in catalytic processes. Illustrative examples of the synthetic applications via stoichiometric reactions will also be covered. For more comprehensive information we refer the reader to the reviews and accounts mentioned above [3, 4, 7]. 

Rod-like mononuclear derivatives have been prepared by the reaction of a polymeric alkynyl gold(I) complex with isocyanides. The mesomorphic properties of three types ofgold(I) acetylide complexes, namely, [Au(CC-Ar)(CN-Ar)J, [Au(CC-R)(CN-Ar)J and [Au(CC-Ar)(CN-R)] (Ar = aryl with aliphatic chain, R = alkyl chain), have been systematically examined. 

The corresponding pyrazole mononuclear derivatives [AuCl(pzH)] have been prepared with the same ligands (Figure 7.41) [38]. Only the monosubstituted non-mesomorphic pyrazole leads to a liquid crystal, not the disubstituted mesomorphic ligand. The complex displays a SmA mesophase on cooling to 69.2 °C, although this is mixed with some crystallization. Moreover, this derivative is luminescent at 77 in the solid state. In addition, the corresponding trinuclear and mononuclear derivatives, namely [ Au(pz) 3] and [Au(Hpz)2]+, which could be expected to be liquid crystals are non-mesomorphic. 

These reactions are analogous to those observed for the corresponding vinylidene complexes the second propadienylidene group is lost, presumably as R2C=(C=C)2=CR2 only in one instance has this hydrocarbon been detected in the thermal decomposition of a mononuclear complex (77). The tendency for the propadienylidene residue to bridge two metal atoms is so great that the binuclear complexes are often formed in reactions designed to generate the mononuclear derivatives (73). 

Mixed Diiutrogen-Phosphine Ligand Complexes 43.3.2.1 Mononuclear derivatives... 

Of the four possible thiadiazoles (1-4), derivatives of 1, 2, and 3 were known for many years and the parent compounds themselves have been described. It was not until 1957 that mononuclear derivatives of 1,2,5-thiadiazole were reported although bicyclic and polycyclic systems involving the 1,2,5-thiadiazole system have been... 

Hermanowitz, A., Kossman, S. (1984). Neutrophil function and infectious disease occupationally exposed to phosphoorganic pesticides role of mononuclear-derived chemotactic factor for neutrophils. Clin. Immunol. Immunopathol. 33 13. 

The only readily available ruthenium carbonyl, Ru3(CO)i2, reacts in a complex manner with many polyolefins to give, in addition to mononuclear derivatives, complexes retaining the Rus cluster and products resulting from hydrogen abstraction. ... 

Other work in this area by Ghedini considered the products of the cyclopalladation of the well-known liquid crystals, the 2-phenylpyrimidines. Initially, dimeric products were obtained and then they were further reacted with species able to cleave the (/r-Cl)2 bridge to give a series of mononuclear derivatives 121. 

The quantitative and selective transformation of the precursor into the dinuclear complex in catalytic conditions, the different catalytic performance of the mononuclear derivative [(BDPBzP)Ru(CH3CN)j]OTf (lower activity and enantioselectivity), the identical catalytic performance of the precursor and of the T12-H2 complex, and the recognized capability of the structurally related Ru(II) complex [(ri2-H2)(dppb)Ru()a.-Cl)3RuCl(dppb)] to maintain the dimeric structure in olefin hydrogenation reactions [35-37] were taken as proofs for the direct involvement of [(BDPzP)(DMSO)Ru((1-C1)3Ru(ti2-H2)(BDPBzP)] in the enantioselective hydrogenation of acetylacetone [68]. 

Substitution of water molecules by Cl or Br has been reported for the chal-cogenide clusters [Mo3Y7(H20)6j (Y = S, Se). Finally, dirhodium cyclo-pentadienyl derivatives with -OH bridges have been reported. An unusual five-coordinated hydrido-hydroxo mononuclear derivative of osmium is obtained upon reaction of HOsCl(CO)(PPr 3)2 with KOH in methanol. ... 

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