Synthesis And Reactivity Studies Of Lhigh Nuclearity Carbido Carbonyl Clusters Of Heptarhenium Iridium And Decaruthenium

Author : Linqing Ma
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (774 download)

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Download or read book Synthesis and Reactivity Studies of High-nuclearity Carbido Carbonyl Clusters of Heptarhenium-iridium and Decaruthenium written by Linqing Ma and published by . This book was released on 1991 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The cluster anion ($\rm Re\sb7C(CO)\sb{21}Ir(C\sb8H\sb{14})(CO)\rbrack \sp{2-}$ has been synthesized by the capping of ($\rm Re\sb7C(CO)\sb{21}\rbrack \sp{3-}$ with the in-situ generated cationic species from the reaction of ($\rm Ir(C\sb8H\sb{14})\sb2(CO)Cl\rbrack \sb2$ and AgBF$\sb4.$ This new heptarhenium-iridium compound reacts with two electron donors to give ligand-substituted compounds ($\rm Re\sb7C(CO)\sb{21}Ir(L)(CO)\rbrack \sp{2-}$ (L = CO, $\rm C\sb2H\sb4,$ PMePh$\sb2,$ and PPh$\sb3),$ and with triphenylsilane and allyl bromide to form the oxidative addition products ($\rm Re\sb7C(CO)\sb{21}Ir(H)(CO)(SiPh\sb3)\rbrack \sp{2-}$ and ($\rm Re\sb7C(CO)\sb{21}Ir(\eta\sp3C\sb3H\sb5)(CO)\rbrack \sp-.$ The reactivities at iridium parallel those of the indenyl complex $\rm (\eta\sp5C\sb9H\sb7)Ir(C\sb8H\sb{14})(CO),$ thus giving further support for the previously proposed analogy between ($\rm Re\sb7C(CO)\sb{21}\rbrack \sp{3-}$ and the cyclopentadienyl ligand and its derivatives. Formulation and characterization of these new compounds are based on elemental analysis, IR, $\sp1$H and $\sp{13}$C NMR spectroscopies, fast-atom bombardment mass spectrometry, and X-ray crystallography. The cluster anion ($\rm Re\sb7C(CO)\sb{21}Ir(CO)\sb2\rbrack \sp{2-}$ undergoes an irreversible framework isomerization process in solution to form a new isomer $\rm \{\lbrack Re(CO)\sb3\rbrack\sb2\lbrack Re\sb5IrC(CO)\sb{17}\rbrack \}\sp{2-}.$ Kinetic studies have been carried out, and a reaction mechanism has also been proposed. In refluxing acetonitrile $\rm \{\lbrack Re(CO)\sb3\rbrack\sb2\lbrack Re\sb5IrC(CO)\sb{17}\rbrack \}\sp{2-}$ loses a Re(CO)$\sb3\sp+$ fragment, leading to the formation of $\rm \lbrack Re\sb6IrC(CO)\sb{20}\rbrack \sp{3-}.$ This analog of $\rm \lbrack Re\sb7C(CO)\sb{21}\rbrack \sp{3-}$ reacts with Au(PPh$\sb3)$Cl to give ($\rm Re\sb6IrC(CO)\sb{20}Au(PPh\sb3)\rbrack \sp{2-}$ and $\rm \{Re\sb6IrC(CO)\sb{20}\lbrack Au(PPh\sb3)\rbrack \sb2\}\sp-,$ which have been characterized by $\sp{31}$P and $\sp{13}$C NMR studies. The known cluster anion ($\rm Ru\sb{10}C\sb2(CO)\sb{24}\rbrack \sp{2-}$ can be prepared via an alternative route involving the redox condensation of ($\rm Ru\sb6C(CO)\sb{16}\rbrack \sp{2-}$ and Ru$\sb5$C(CO)$\sb{15}.$ Substitution of two apical carbonyls in ($\rm Ru\sb{10}C\sb2(CO)\sb{24}\rbrack \sp{2-}$ by one diphenylacetylene molecule gives the compound ($\rm Ru\sb{10}C\sb2(CO)\sb{22}(C\sb2Ph\sb2)\rbrack \sp{2-},$ which contains a new ruthenium-ruthenium bond between the two apical atoms in the bioctahedral structure. Carbonyl ligand dynamic exchange behavior has been observed by variable-temperature $\sp{13}$C NMR spectroscopy.