Cysteine(2-), alkyl, and siloxide complexes of ruthenium(VI) and iron(III)

Abstract

Transition metal-cysteine complexes are reviewed in Chapter 1. Compounds for which X-ray crystal structures have been determined are considered first followed by those for which only spectroscopic evidence exists. The synthesis and characterization of several trans-dioxoruthenium(VI) species containing cysteine(2$-)$ and related ligands is reported in Chapter 2. The compounds $\rm Ru(O)\sb2(py)\sb2(SC\sb2H\sb5)\sb2,$ Ru(O)$\sb2$(py)$\sb2\{$SCH$\sb2$CH$\sb2$C(O)O$\},$ Ru(O)$\sb2$(bpy)$\{$SCH$\sb2$CH(NCHO)C(O)O$\},$ Ru(O)$\sb2$(py)$\{$SCH$\sb2$CH(NHCOMe)C(O)O$\},$ and Ru(O)$\sb2$(bpy)$\{$SCH$\sb2$CH(NHCOMe)C(O)O$\}$ have been synthesized in yields ranging from 60-87% from Ru(O)$\sb2$(OH)$\sb2$(py)$\sb2$ and Ru(O)$\sb2$Cl$\sb2$(bpy) using either ethane thiol, 3-mercaptopropionic acid, N-acetyl-L-cysteine, or N-formyl-L-cysteine. The iron(II) and iron(III) complexes (NBu$\sb4\rbrack\sb{\rm n}$ (Fe(SCH$\sb2$CH(NHCOCH$\sb3)$COO)$\sb2$) (n = 1,2) have been synthesized by the addition of two equivalents of N-aceteyl-L-cysteine to methylene chloride solutions of either (NBu$\sb4$) (Fe$\sp{\rm III}$(OSiMe$\sb3)\sb4$) or (NBu$\sb4\rbrack\sb2$(Fe$\sp{\rm II}$(OSiMe$\sb3)\sb4$) and are described in Chapter 3. The synthesis and characterization of the first monooxo ruthenium(VI) tetraalkyl complex, (Ru(O)(CH$\sb2$Si(CH$\sb3)\sb3)\sb4$), is reported in Chapter 4 along with that for Ru(CH$\sb2$Si(CH$\sb3)\sb3)\sb4.$ These complexes are readily synthesized from trans-(PPN) $\sb2$(Ru(O)$\sb2$Cl$\sb4$) and either four or ten equivalents of trimethylsilyl-methylmagnesium chloride in THF or methylene chloride respectively. In Chapter 5, combination of (C$\sb5$H$\sb9)\sb7$Si$\sb7$O$\sb{12}$H$\sb3$ with either (NBu$\sb4$) (Fe(OSiMe$\sb3)\sb4$) or (NBu$\sb4$) (Fe(Cl)$\sb4$) and triethylamine gives the iron-containing silsesquioxanes (NBu$\sb4$) ((C$\sb5$H$\sb9)\sb7$Si$\sb7$O$\sb{12}$FeCl) and (NBu$\sb4$) ((C$\sb5$H$\sb9)\sb7$Si$\sb7$O$\sb{12}$FeOSi(CH$\sb3)\sb3$) in yields of at least 60% after recrystallization from toluene/hexane. These complexes can be modified by substitution for the free siloxide or chloride ligand to give (NBu$\sb4$) ($\{$(C$\sb5$H$\sb9)\sb7$Si$\sb7$O$\sb{12}$Fe$\}\sb2$O), (NBu$\sb4$) ((C$\sb5$H$\sb9)\sb7$Si$\sb7$O$\sb{12}$FeOOC(CH$\sb3)\sb3$), and (NBu$\sb4$) ((C$\sb5$H$\sb9)\sb7$Si$\sb7$O$\sb{12}$Fe(S-cysteine-OMe)).