Tertiary amine ligands

Scheme 1.39 Test reaction with sulfide-tertiary amine ligands incorporating 1,2-aminothioethers.

These tru 5-dioxoruthenium(VI) complexes have characteristic UV-vis absorption spectra. The fj-saturated nature of the macrocyclic tertiary amine ligands enables the high-energy metal-localized transition to be observed. " The weak vibronic structured band at 370-400nm has been assigned to (0 ) —> Ru charge transfer transition that is vibronically coupled to the... 

As in the case of ruthenium, a series of tra 5-dioxoosmium(VI) complexes with macrocyclic tertiary amine ligands, trans- 0 0)2(l )f (L=14-TMC, 15-TMC, 16-TMC, CRMes), have been synthesized by the method shown in Scheme 13. ... 

The electrochemistry of dioxoruthenium(VI) and dioxoosmium(VI) complexes with polypyridyl and macrocyclic tertiary amine ligands has been extensively studied by cyclic voltammetric techniques. In general, cA-dioxo species have higher reduction potentials than the corresponding trans-Aiaxo species. " " For the trans-Aioxo species, the d, orbital ordering... 

The electrochemistry of dioxoosmium(VI) complexes has also been extensively studied. The tra 5-dioxoosmium(VI) complexes of polypyridyl and macrocyclic tertiary amine ligands display very similar proton-coupled electron transfer couples. In aqueous solutions at pH < 5-7 the cyclic voltammograms of n-a i-[0s (0)2(bpy)2] show a remarkable reversible three-electron couple and a one-electron Os coimle. In the Pourbaix diagram two break points are observed in the pH dependence of the Os couple, which correspond to the pAa values of Os —OH2 and Os —(OHXOH2) (Figure 10). The redox reactions are shown in Equations (41)-(43). At pH >8 the 3e Os wave splits into a pH-independent le Os wave and a 2e/2H" Os wave (Equations (44) and (45)). 

Terminal monoalkenes were alkylated by stabilized carbanions (p a 10-18) in the presence of 1 equiv. of palladium chloride and 2 equiv. of triethylamine, at low temperatures (Scheme l).1 The resulting unstable hydride eliminate to give the alkene (path b), or treated with carbon monoxide and methanol to produce the ester (path c).2 As was the case with heteroatom nucleophiles, attack at the more substituted alkene position predominated, and internal alkenes underwent alkylation in much lower (=30%) yield. In the absence of triethylamine, the yields were very low (1-2%) and reduction of the metal by the carbanion became the major process. Presumably, the tertiary amine ligand prevented attack of the carbanion at the metal, directing it instead to the coordinated alkene. The regiochemistry (predominant attack at the more sub-... 

The high solubility of tertiary polyamine-alkali-metal salt chelates in benzene has been mentioned briefly. The data in Table XI illustrate the range of solubilities observed for LiBr and LiNO chelates of bi-, tri-, tetra-, and pentadentate tertiary amine ligands. Benzene solutions containing several moles of chelate have been obtained. 

The dihydroxylation of olefins with an osmium catalyst also utilizes chiral tertiary amine ligands to achieve high yields and enantioselectivity. Soon after Krief and coworkers reported on the coupled 02/PhSeCH2Ph oxidation [34], Bel-ler and coworkers discovered a direct 02-coupled catalytic aerobic oxidation of olefins was possible using a phosphate-buffered pH 10.4 solution (Scheme 5.21) [69]. Under increased pressure with air rather than O2, the catalyst remains active and a TOP of 40 h is possible. This system does not quite achieve as high an enantioselectivity as the AD-Mix methods [70]. 

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