The synthesis and stereodynamics of cyclopentadienyl ruthenium chalcogenide clusters

A diamagnetic salt of the (MeC$\sb5$H$\sb4)\sb4$Ru$\sb4$S$\sb4\sp{2+}$ cluster cation was obtained by oxidation of (MeC$\sb5$H$\sb4)\sb4$Ru$\sb4$S$\sb4$ with ((MeC$\sb5$H$\sb4)\sb2$Fe) PF$\sb6$. Variable temperature $\sp1$H NMR measurements showed that (MeC$\sb5$H$\sb4)\sb4$Ru$\sb4$S$\sb4\sp{2+}$ is dynamic in solution; it exhibits signals for two chiral Ru sites at low temperatures but only one symmetrical Ru environment at high temperatures. Similar dynamic behavior was observed for (MeC$\sb5$H$\sb4)\sb4$Ru$\sb4$Se$\sb4$(PF$\sb6)\sb2$, while samples of (MeC$\sb5$H$\sb4)\sb4$Ru$\sb4$Te$\sb4$(PF$\sb6)\sb2$ showed only slight line broadening at low temperatures. The concentration independence of the coalescence temperature (T$\sb{\rm c}$) of the CH$\sb3$C$\sb5$H$\sb4$ signals showed that the exchange processes are intramolecular. The exchange barrier of (Me$\sb3$SiC$\sb5$H$\sb4)\sb4$Ru$\sb4$S$\sb4$(PF$\sb6)\sb2$ was found to be similar to those of (MeC$\sb5$H$\sb4)\sb4$Ru$\sb4$E$\sb4$(PF$\sb6)\sb2$ (E = S, Se), which indicates that the exchange processes do not involve hindered RCp rotation. The activation parameters were evaluated from analyses of the line shapes as a function of temperature; the free energies of activation range from 52 to 55 kJ/mol for all clusters.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Chemistry

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Houser, Eric Jon

Contributors dc:contributor

• Rauchfuss, Thomas B.

• Chemistry, Inorganic

Statement dc:rights

• Copyright 1994 Houser, Eric Jon

Language dc:language

eng

Identifier

AAI9416373
(UMI)AAI9416373

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/21437