No abstract

Kinetic studies of the reactions of Ru(NH3)5pz2+ (pz = pyrazine), Ru(NH3)4bpy2+ (bpy = 2,2'-bipyridine), Ru(NH3)5pzMe3+ (pzMe+ = JV-methylpyrazinium), Ru2(NH3)10pz5+, RuRh(NH3)10pz5+, and Ru2(NH3)10pz4+ with S2Og1 2" are interpreted on the basis of a mechanism involving ion-pair formation between the ruthenium complexes and S2Os2" followed by one-electron transfer from Ru(II) to S2Os2". The dependence of the rate constants upon the standard free energy changes for the above reactions as

2‐Methyl‐4‐(4‐pyridyl)‐3‐butyn‐2‐ol (2) was prepared in 70% yield by the reaction of 4‐bromopyridine with 2‐methyl‐3‐butyn‐2‐ol in diethylamine in the presence of bis(triphenylphosphine)palladium(II) chloride and copper(I) iodide. Removal of the protective group in 2 by refluxing with sodium hydroxide in toluene yields (90%) 4‐ethynylpyridine (3). Oxidative coupling of 3 in pyridine by dioxygen in the presence of copper(I) chloride produces a 92% yield of 1,4‐bis(4‐pyridyl)butadiyne.

The equilibrium constant for the reaction CH, (COOH)