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Shapley, John R. Simerly, Scott W. 2011-05-07T12:36:21Z 2011-05-07T12:36:21Z 10000-01-01 1991 The second-order rate constants for the reactivity of (Re$\sb7$C(CO)$\sb{21}$Rh(CO)$\sb2$) $\sp{2-}$ towards phosphorus donors were determined. In order to correlate the results to electronic and/or steric effects, steric profiles relating log k$\sb2$ to an intrinsic reactivity $(\alpha),$ an electronic parameter $(\beta),$ and a steric parameter $(\theta)$ were constructed. From differences in intrinsic reactivity for phosphines and phosphites, an intermediate configuration involving a bridging carbonyl has been proposed for the reaction of (Re$\sb7$C(CO)$\sb{21}$Rh(CO)$\sb2$) $\sp{2-}$ with various phosphorus donors (PY$\sb3).$ Nitrosylation of a series of mixed-metal heptarhenium clusters, (Re$\sb7$C(CO)$\sb{21}$ML$\sb{\rm n}$) $\sp{2-},$ gave the mono-substituted products, (Re$\sb7$C(CO)$\sb{20}$ML$\sb{\rm n}\rbrack\sp-.$ A variety of spectroscopic techniques were used to characterize the reaction products. Variable temperature $\sp{13}$C NMR studies determined the solution structure of (Re$\sb7$C(CO)$\sb{20}$(NO)Rh(CO)$\sb2$) $\sp-.$ From kinetic studies, the nitrosyl substituted cluster (Re$\sb7$C(CO)$\sb{20}$(NO)Rh(CO)$\sb2$) $\sp-$ exhibits enhanced reactivity toward phosphorus ligands in comparison with (Re$\sb7$C(CO)$\sb{21}$Rh(CO)$\sb2$) $\sp{2-}.$ The carbonyl ligands bound to (Re$\sb7$C(CO)$\sb{21}$Rh(CO)$\sb2$) $\sp{2-}$ display unusual intermolecular and intramolecular exchange. Upon treatment with $\sp{13}$CO, (Re$\sb7$C(CO)$\sb{21}$Rh(CO)$\sb2$) $\sp{2-}$ is selectively $\sp{13}$CO enriched to ($\rm Re(CO)\sb3Re\sb6C(\sp{13}CO)\sb{18}Rh(\sp{13}CO)\sb2\rbrack \sp{2-}$. A capping Re(CO)$\sb3$ moiety trans to the rhodium cap remains unenriched. Formation of the radical species (Re$\sb7$C(CO)$\sb{21}$Rh(CO)$\sb2\rbrack\sp-$ by chemical oxidation results in complete carbonyl scrambling, which is revealed upon reduction to the parent cluster ($\rm Re(\sp{13}CO)\sb3Re\sb6C(\sp{13}CO)\sb{18}Rh(\sp{13}CO)\sb 2\rbrack \sp{2-}.$ The selectively $\sp{13}$Co enriched cluster (Re(CO)$\sb3$Re$\sb6$C($\sp{13}$CO)$\sb{18}$) $\sp{2-}$ has been formed in a decapping reaction of ($\rm Re(CO)\sb3Re\sb6C(\sp{13}CO)\sb{18}Rh(\sp{13}CO\sb2\rbrack \sp{2-}$ with excess PPh$\sb3$ in acetonitrile. Two-electron oxidation of (Re$\sb7$C(CO)$\sb{21}$) $\sp{3-}$ in the presence of P(OPh)$\sb3$ affords (Re$\sb7$C(CO)$\sb{21}$(P(OPh)$\sb3)$) $\sp-.$ $\sp{13}$C NMR indicates that this cluster exhibits partial charge separation. (Re$\sb7$C(CO)$\sb{21}$(P(OPh)$\sb3)$) $\sp-$ decomposes in acetonitrile to form (Re$\sb6$C(CO)$\sb{19}$) $\sp{2-}$ and (Re(CO)$\sb3$(P(OPh)$\sb3)\sb2$(NCCH$\sb3)$) $\sp+,$ and therefore it represents a directly observed intermediate in a cluster decapping reaction. Made available in DSpace on 2011-05-07T12:36:21Z (GMT). No. of bitstreams: 2 license.txt: 4922 bytes, checksum: 910b249b4beec47e7ab768910c8f966f (MD5) 9210992.pdf: 3597419 bytes, checksum: beff29c7e5a9997a87eabf013f1fad00 (MD5) Previous issue date: 1991 Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding (hding2@illinois.edu) on 2011-05-07T14:43:13Z Item is restricted indefinitely. Restriction data tranferred 2014-07-01T11:18:53-05:00 Original Data Group with Access UIUC Users [automated] Release Date: none Reason: ETDs are only available to UIUC Users without author permission ETDs are only available to UIUC Users without author permission U of I Only AAI9210992 (UMI)AAI9210992 http://hdl.handle.net/2142/20337 eng Copyright 1991 Simerly, Scott W. Chemistry, Inorganic Substitution and redox reactions of heptarhenium cluster derivatives text Chemistry Chemistry University of Illinois at Urbana-Champaign Dissertation Ph.D.