Metalation diamine complexes

Table 3.1 summarises the influence of the diamine ligands on the equilibrium constant for binding of 3.8c to the ligand-metal ion complex (K ) and the second-order rate constant for reaction of the ternary complex (ICjat) (Scheme 3.5) with diene 3.9. 

Oxygen-exchange reactions of square-pyramidal metal(V) complexes have been reported [14]. In monooxotechnetium(V) and monooxorhenium(V) complexes with N,iV -bis(mercaptoaeetyl)butane-l,4-diamine(DBDS), the exchange of oxygen between the complexes and water in DMSO medium ... 

For the preparation of CoSalophen Y the Co—Y was impregnated by salicy-laldehyde, and 1,2-phenylenediamine in methanol was added slowly to the mixture.107 This was a successful encapsulation of a salen-type complex with larger diamine than the ethylenediamine, a successful preparation of an encaged metal-salen complex by the intrazeolite ligand synthesis method, and a successful intrazeolite synthesis using two different precursor molecules. 

Metal salen complexes can adopt non-planar conformations as a result of the conformations of the ethane-1,2-diyl bridge. The conformations may have Cs or C2 symmetry, but the mixtures are racemic. Replacement of the ethylenediamine linker by chiral 1,2-diamines leads to chiral distortions and a C2 chiral symmetry of the complex due to the half-chair conformation of the 5-membered ring of the chelate. Depending on substitution at the axial positions of the salen complex, the symmetry may be reduced to Q, but as we have seen before in diphosphine complexes of rhodium (Chapter 4) and bisindenyl complexes of Group 4 metals (Chapter 10) substitution at either side leads to the same chiral complex. Figure 14.10 sketches the view from above the complex and a front view. 

In 1996, Carreira reported a catalytic enantioselective aUylation of aldehydes using BlNOL-modified Tip4. More recently, Kobayashi reported a catalytic enantioselective aUylation of hydrazono esters in aqueous media using ZnF2-chiral diamine complex, [Eq. (13.36)]. In both reactions, reaction mechanism via dual activation of the substrate by Lewis acid metals and aUylsUanes by fluoride is proposed ... 

Sodium acetylides are the most common reagents, but lithium, magnesium and other metallic acetylides have also been used. A particularly convenient reagent is lithium acetylide-ethylene diamine complex. Alternatively, the substrate may be treated with the alkyne itself in the presence of a base, so that the acetylide is generated in situ. 1,4-Diols can be prepared by treatment of aldehyde with dimetalloacetylenes. 

A wide range of metals and ligand combinations have been demonstrated to effect the ATH reaction and in this book we concentrate on the systems that have demonstrated high activities and ees that would be the requirement of an industrial application. The initial breakthrough in this area came in 1995 with the report from Ohkuma et alP on the use of chiral monotosylated diamine complexes for asymmetric transfer hydrogenation. 

Kx for copper (II)-diamine complex is 10.36 and 9.45 for 1,2-ethanediamine and 1,3-propanediamine, respectively (-2)]. The large difference in the stabilities of the two copper (II)-diamine complexes is attributed to an unfavorable entropy effect associated with an increase in the size of the metal-chelate ring (2). Extrapolating to the / -ketoimine derivatives, it seems reasonable to expect that the stability of bisacetylacetonetrimethylenediiminocopper(II) would be less than that of the ethylenediamine analog and to suspect that the former compound is less stable than bis-(4-iminopentane-2-ono) copper (II). That this is reasonable is... 

The chelating behaviour of 1,2-diamines towards Cu, Ni and Zn when the stereochemical relationship between the two amino groups is restricted has been studied.196 Alicyclic trans diamines gave 1 1 complexes more stable than those formed with the cis isomers. The stability of the metal chelates with 3,3-dimethyl-l,2-diaminobutane is comparable to that of the trans isomers. The difference in stability of the trans and cis diamine complexes increased in the order Cu > Zn > Ni, and both the stereochemical requirements of the ligands and differences in the coordination geometry of the metal are thought to be responsible. Little difference in stability was observed for 1 2 complexes, except in the case of Ni. 

Molecular mechanics and dynamics studies of metal-nucleotide and metal-DNA interactions to date have been limited almost exclusively to modeling the interactions involving platinum-based anticancer drugs. As with metal-amino-acid complexes, there have been surprisingly few molecular mechanics studies of simple metal-nucleotide complexes that provide a means of deriving reliable force field parameters. A study of bis(purine)diamine-platinum(II) complexes successfully reproduced the structures of such complexes and demonstrated how steric factors influenced the barriers to rotation about the Pt(II)-N(purine) coordinate bonds and interconversion of the head-to-head (HTH) to head-to-tail (HTT) isomers (Fig. 12.4)[2011. In the process, force field parameters for the Pt(II)/nucleotide interactions were developed. A promising new approach involving the use of ab-initio calculations to calculate force constants has been applied to the interaction between Pt(II) and adenine[202]. 

Aromatic primary diamines, dithiols, and diethynyl compounds are oxidatively polymerized with metal-amine complexes as the catalyst to yield poly (azopheny-lene) [78], poly(disulfide) [79], and polydiyne [80], respectively (Figure 7, Eq. 

Deoxygenation can be achieved with transition-metal atoms (Ti, V, Cr, Co, Ni) in a high vacuum at low temperature, V and Cr being the most active cis-trans mixtures are obtained with low conversions. The reaction of cyclohexene oxide with transition-metal complexes has been studied on a zeolite matrix of the complexes examined, the copper-phthalocyanine and cobalt-diamine complexes are the most active. 

The NaSa-containing analog of sarcophaginate 3 was obtained from 5,5 -bis-(4-amino-2-thiabutyl)-3,7-dithianonane-l,9-diamine by Scheme 63 [144], After reduction with zinc dust the resultant NaSa-sarcophaginate underwent demetallation with NaCN. Thus, the ligand obtained may be employed for the synthesis of other metal ion complexes. 

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