The reactivity of cationic [trioxo-(1,4,7-triazacyclononane) rhenium(VII)] and oxorhenium(V) complexes containing triazamacrocycles

Abstract The reduction of colourless [LRe VII O 3 ]Br in an acetone-water mixture (6: 1) with zinc amalgam affords green, air-sensitive [LRe V O 2 Br] which forms a violet complex [LReO(μ-O) 2 ReOBr 2 ]in aqueous solution (L = 1,4,7-triazacyclononane; C 6 H 15 N 3 ). From a similar reduction of [LReO 3 ]ReO 4 the violet neutral complex [LReO(μ-O) 2 ReO(ReO 4 ) 2 ] was obtained. [LReO 3 ] + is deprotonated in alkaline solution (p K a = 10.3 + 0.2, 25°C) and [(C 6 H 14 N 3 )ReO 3 ] was isolated as a yellow solid. The latter amido rhenium(VII) compound reacted in dimethylformamide with RX (R = CH 3 , benzyl; X = Cl), affording at the cyclic amine, N,N′,N″-trisalkylated complexes of the type [L′ReO 3 ]X. The monomeric rhenium(V) complexes [LReOX 2 ]X (X = Cl, Br, I) were obtained from the reaction of [ n -Butyl 4 N]ReOX 4 and L in acetonitrile. IR, UV-vis, 17 O NMR spectra of these compounds are reported.