Arene-metal complexes interaction

D. Symmetry Classification of Interaction in Arene-Metal Complex 42... 

Borazine is isoelectronic and isostructural with benzene and may act as a six-electron donor in complex chemistry. In contrast to arene ligands of arene-transi-tion-metal complexes, coordinated borazines lose their planarity and are slightly puckered . Nevertheless, the B atoms show interactions with metal atoms. 

Longer Hg-7r interactions are observed in the /> ra-/-butylcalix[4]arene mercury complex 162. The mercury atom forms primary bonds with the two sulfur atoms and engages in weaker secondary interactions with two arene rings of the calixarene whose centroids sit at 3.07-3.11 A from the metal center.201... 

Labelling experiments provided the evidence that the Fe1- and Co1-mediated losses of H2 and 2H2 from tetralin are extremely specific. Both reactions follow a clear syn- 1,2-elimination involving C(i)/C(2) and C(3)/C(4), respectively. In the course of the multistep reaction the metal ions do not move from one side of the rr-surface to the other. The kinetic isotope effect associated with the loss of the first H2 molecule, k( 2)/k(Y)2) = 3.4 0.2, is larger than the KIE, WFLj/ATHD) = 1.5 0.2, for the elimination of the second H2 molecule. A mechanism of interaction of the metal ion with the hydrocarbon n-surface, ending with arene-M+ complex 246 formation in the final step of the reaction, outlined in equation 100, has been proposed241 to rationalize the tandem MS studies of the unimolecular single and double dehydrogenation by Fe+ and Co+ complexes of tetraline and its isotopomers 247-251. 

We tested whether the saccharide binding site on the upper rim could communicate with the metal binding site on the lower rim through the calix[4]arene cavity. The CD band weakened with increasing concentrations of Na+, Mg2+, or Ca2+. 78 On the other hand, when K+, Rb+, or Cs+ was added, the CD intensities increased and the spectral shape was changed. 78 For a number of reasons, we consider the new band to be attributable to the l,2-alternate-3- D-glucose-metal complexes. Therefore, this system is a unique example that exhibits both negative and positive allosteric interactions between metal ions and saccharides in a calix[4]arene host. 

Once the ruthenium or osmium arene organometallic complex is activated with the formation of the aqua species, [Ru/Os(r 6-arene)(OH2)(X)(Y)] (Chart 3), the metal becomes a potential centre for nucleophilic attack by biomolecules. The binding of Run/Osn arene complexes to nucleobases is of special interest, since DNA could be the ultimate target for this class of organometallic complexes. A number of studies have confirmed this postulate [86, 87] and investigated in detail such interactions [53, 54, 72, 88-93]. DNA interactions of Ru and Os arene complexes have recently been reviewed [94],... 

---