Mono complexes

Mixed mono-complexes can be made (Figure 3.68) the trans-influence of tertiary phosphine on the Pt-S bond is noticeable [121]. 

The oxidation by Mn(lII) chloride involves three complexes and the kinetic data of Taube " are summarised in Table 15. The greater thermal stability of the /m-complex is considered to result from the lowering of the free energy relative to the transition state as compared with bis- and mono-complexes. The study of MnC204 was based on the Mn(III)-catalysed chlorine oxidation of oxalic acid. ... 

A general strategy developed for the synthesis of supramolecular block copolymers involves the preparation of macromolecular chains end-capped with a 2,2 6/,2//-terpyridine ligand which can be selectively complexed with RUCI3. Under these conditions only the mono-complex between the ter-pyridine group and Ru(III) is formed. Subsequent reaction with another 2,2 6/,2"-terpyridine terminated polymer under reductive conditions for the transformation of Ru(III) to Ru(II) leads to the formation of supramolecular block copolymers. Using this methodology the copolymer with PEO and PS blocks was prepared (Scheme 42) [ 107]. 

The most controversial issue is the number and exact stoichiometries of the iron(III)-sulfito complexes formed under different experimental conditions. Earlier, van Eldik and co-workers reported the formation of a series of [Fe(SO ) ]3-2" (n = to 3) complexes and the [Fe(S03)(0H)] complex (89,91,92). The stability constants of these species were determined by evaluating time resolved rapid-scan spectra obtained from the sub-second to several minutes time domain. The cis-trans isomerization of the complexes was also considered, under feasible circumstances. In contrast, Betterton interpreted his results assuming the formation and linkage isomerization of a single complex, [Fe(SC>3)]+ (93). In agreement with the latter results, Conklin and Hoffmann also found evidence only for the formation of a mono-complex (94). However, their results were criticized on the basis that the experiments were made in 1.0 M formic acid/formate buffer where iron(III) existed mainly as formato complex(es). Although these reactions could interfere with the formation of the sulfito complex, they were not considered in the evaluation of the results (95). Finally, van Eldik and co-workers re-examined the complex-formation reactions and presented additional data in support of... 

Terpyridine ligands are known to form mono- and Ins-complexes with a wide variety of transition metal ions [321]. The stability constants and the kinetics of formation of these different complexes strongly depend on the nature of the used metal ions [322], In this respect, Rum is known to form a very stable mono-complex with one terpyridine ligand, while Ru11 only forms a stable bzs-complex with two terpyridine ligands [323]. 

Terpyridine moieties have been introduced as a terminal unit of macromolecules. In a subsequent procedure the two-step self-assembly process based on Rum/Run chemistry was used for polymers end-capped with the 2,2/ 6/,2 -terpyridine ligand. More precisely, the terpyridine-functionalized polymers were complexed with RUCI3 to selectively form a mono-complex. In a further step, this mono-complex was reacted under reducing conditions with other uncomplexed 2,2/ 6/,2/-terpyridine-terminated polymer blocks in order to form an asymmetrical AB ruthenium(II) frzs-complex. 

DR. MARGERUM Yes, it does turn up in a number of instances. The example you are talking about was an EDTA reaction with a copper triglycine in which the released triglycine catalyzed the substitution of the EDTA. This resulted from the fact that the bis-triglycine complex is faster to undergo substitution than is the mono complex. The released triglycine formed a bis complex and the EDTA then attacked that. 

The reaction of Cu(II) ion with acetylacetone (acacH) to form the mono complex Cu(acac) in methanol is interpreted in terms of the scheme... 

We find that in looking at the data for the ethylenediamine we have more or less normal behavior the highest complex dissociates with the fastest rate, and as the complexity of the ion decreases the rate constant falls off. With phenan-throline, however, we find that the highest complex is actually the slowest to dissociate. The bis complex is the fastest, and once again we have a decrease with the mono complex. 

CpCo(mcp)2, which in turn can be further transformed to the mono-complex CpCo(PPh3)(mcp) by exchange of one methylenecyclopropane ligand with PPhj (equation 312). Although both complexes are isolable crystals, they are thermally less stable than the analogous Feist s ester complexes. CpCo(mcp)2 readily undergoes thermal isomerization at 110 °C, to give cyclopropyl-substituted -butadiene complexes (see below). 

Aluminum binds to nucleoside phosphates mainly through the basic terminal phosphate groups. Nucleosides mono-, di-, and triphosphates demonstrate similar phosphate basicity. Aqueous solutions of Al3+ and nucleoside phosphates have a tendency to form ternary complexes with hydroxide in a pH-dependent manner. In addition, there is a possibility of Al3+-bridged complexes being formed. Fig. 3 shows the species distribution for the A13+-ATP system. At physiological pH the merged hydroxo mono complexes predominate [9, 18]. 

Dipicolinates (pyridine-2,6-dicarboxylates) have been investigated in some detail with structures determined for several tris complexes such as Na3[Nd(dipic)3]-15H20 and Na3[Yb(dipic)3]13H20, typical of the early and later lanthanides, respectively. The lanthanides have essentially tricapped trigonal prismatic coordination geometries, isostruc-tural along the lanthanide series they have been the subject of important solution NMR studies. Mono and bis complexes can also be synthesized the mono complex [Nd(dipic)(H20)4] CIO4 has a polymeric structure in which each picolinate is bound to three different (nine-coordinate) neodymium ions. 

However, the less stable mono complexes have been recently isolated. ... 

The 3-acetylamido-pentane-2,4-dione (amacH) (13) is a highly enolized and acidic substance which is very soluble in water. It was first reported to form a Cu11 complex [Cu(amac)2] by Cotton," and has been used to study the kinetics of the mono complex M(amac)+ formation (M = Co, Ni, and Cu) in aqueous solution.100 The chemistry of the analogous 3-(hydroxyimino)-pentane-2,4-dione has also been explored.101... 

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