A novel cryptand was synthesized which contained a 3,5-disubstituted-4- oxahexacyclo[5.4.1.02,6.03,10.05,9.08,11] dodecane "cage" moiety. In alkali metal picrate extraction experiments the cryptand exhibited high avidity towards Rb+ and Cs+, when compared with the corresponding model compound. A computational study of a series of cage-functionalized cryptands and their alkali metal-complexes was performed. The X-ray crystal structure of a K+-complexed bis-cage-annulated 20-crown-6 was obtained. The associated picrate anion was found to be intimately involved in stabilization of the host-guest complex. The interaction energy between the host-guest complex and picrate anion has been calculated, and the energy thereby obtained has been corrected for basis set superposition error.

The kinetics for the bridge-to-chelate isomerization of the dppe ligand in H4Ru4(CO)10(dppe) have been investigated by UV-vis and NMR spectroscopies over the temperature range of 308-328 K. The isomerization of the ligand-bridged cluster 1,2-H4Ru4(CO)10(dppe) was found to be reversible by 31P NMR spectroscopy, affording a Keq = 15.7 at 323 K in favor of the chelating dppe isomer. The forward (k1) and reverse (k-1) first-order rate constants for the reaction have been measured in different solvents and in the presence of ligand trapping agents (CO and PPh3). On the basis of the activation parameters and reaction rates that are unaffected by added CO and PPh3, a sequence involving the nondissociative migration of a phosphine moiety and two CO groups between basal ruthenium centers is proposed and discussed. The substitution of the MeCN ligands in the activated cluster 1,2-Os3(CO)10(MeCN)2 by the diphosphine ligands dppbz proceeds rapidly at room temperature to furnish a mixture of bridging and chelating Os3(CO)10(dppbz) isomers and the ortho-metalated product HOs3(CO)9[μ-(PPh2)C=C{PPh(C6H4)}C4H4]. Thermolysis of the bridging isomer 1,2-Os3(CO)10(dppbz) under mild conditions gives the chelating isomer 1,1-Os3(CO)10(dppbz), molecular structure of both the isomers have been determined by X-ray crystallography. The kinetics for the ligand isomerization has been investigated by UV-vis …