Halides dimers, structure

In view of the facile oxidation of 10.13a-c it is not surprising that some metathetical reactions with metal halides result in redox behaviour. Interestingly, lithium halides disrupt the dimeric structures of 10.13a or 10.13c to give distorted cubes of the type 10.14, in which a molecule of the lithium halide is entrapped by a Ei2[E(N Bu)3] monomer. Similar structures are found for the MeEi, EiN3 and EiOCH=CH2 adducts of 10.13a. In the EiN3 adduct, the terminal... 

In the reactions of 10.13a with alkali metal terr-butoxides cage expansion occurs to give the sixteen-atom cluster 10.15, in which two molecules of MO Bu (M = Na, K) are inserted into the dimeric structure. The cluster 10.13a also undergoes transmetallation reactions with coinage metals. For example, the reactions with silver(I) or copper(I) halides produces complexes in which three of the ions are replaced by Ag" or Cu" ions and a molecule of lithium halide is incorporated in the cluster. ... 

The aqua ion as a ligand is discussed in section 4.5. Silver forms a range of light-sensitive, insoluble carboxylates that find application in the synthesis of, for example, alkyl halides and esters. The benzoate, trifluoroacetate and perfluorobutyrate have dimeric structures others are polymers (Figure 4.6). 

The diphenyliodine(III) halides have dimeric structures in the solid state,63 directly comparable with that of IC13.29 Thus, these compounds have a planar coordination of the iodine atom by two carbon and two bridging halogen atoms. This corresponds to the 12-electron, octahedral arrangement. The I—Cl bonds in the chloride, of 3.085 A, are longer than those of 2.70 A in the trichloride and presumably reflect the significance63 of the ionic form [Ph2I]+[Cl] 2. 

Most of the diphosphine complexes of silver known are of the type AgXP2, where X is a halide and P2 is a diphosphine. In general, they adopt dimeric structures in the solid state, with the exception of the silver chloride complex of 2,ll-bis(diphenylphosphinomethyl)benzo[c]-phenanthrene which is monomeric. 

Tri(f-butyl)phosphine and tri(o-tolyl)phosphine form 1 1 complexes with mercury(II) halides and with Hg(SCN)2. Physicochemical measurements, Le. conductance, molecular weight determinations, IR and Raman spectra, indicate a dimeric structure (26) of Cy, skeletal symmetry.493... 

The possibility of formation of dimeric structures should be taken into account in the syntheses of metal-halide complexes of other ligands. In this respect, the transformation (3.72) is interesting and representative, in which not only monomeric mononuclear 637, but also dinuclear 638 complexes were isolated and their structures determined by x-ray diffraction [89] ... 

Rhodium(III) halides form [RhX2 Sb(o-C6H4Me)3 ] complexes when allowed to react with tri(o-tolyl)stibine. Despite their stoichiometry and diamagnetism there is no evidence for their being either o-metallated or hydridorhodium(III) complexes. It is believed they have the planar dimeric structure (32). Intramolecular interactions in such dimers could account for their diamagnetism and the non-equivalence of the methyl protons in their H NMR spectrum.278... 

We have performed Xa calculations on the various lithium halide dimers, from which we have determined the sequence of molecular orbitals, their sjmnnetries and the energy span of the valence band. These calculations [summarized elsewhere (18)] are in reasonable agreement with experiment, and also Indicate that the dimers have a higher first I.P. than the monomers. The geometries chosen for these calculatians were the well-established planar-rhombic structures, with angles and distances taken from electron diffraction and infrared matrix isolation results. 

The sttuctures of organoaluminum halides R AlXs are dominated by dimeric structures with AI2X2 four-membered rings for X = Cl, Br, and I. Unlike the aluminum alkyls, these hahde bridges are electron-precise and result from intermolecular Lewis acid-base complexation. These dimers do dissociate and readily react with Lewis bases, but the enthalpies of dissociation are higher than those for the aluminum alkyls. In many cases, the strength of the association is sufficient that dimers are observed in the gas phase. 

Zeng, Y. R, Sharpe, S. W., Shin, S. K., Wittig, C., and Beaudet, R. A., Infrared spectroscopy of C02 D(H)Br Molecular structure and its reliability, J. Chem. Phys. 97, 5392-5402 (1992). Muenter, J. S., Potential functions for carbon dioxide-hydrogen halide and hydrogen halide dimer van der Waals complexes, J. Chem. Phys. 103, 1263-1273 (1995). 

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