Octabutylthiophthalocyaninatoiron(II): electrochemical properties and interaction with cyanide

The preparation of the thiol-derivatised iron(II) phthalocyanine (FePc) complex, 2,3,9,10,16,17,23,24octabutylthiophthalocyaninatoiron(II), FePc(SC4H9)(8), is described. Electrochemical data obtained by both cyclic voltammetry and Osteryoung square wave voltammetry in DMF showed four redox couples. Kinetics and equilibrium measurements for the interaction of cyanide with FePc(SC4H9)(8) at 25.0 +/- 0.5 degreesC in both DMSO and DMF are reported. Gradual spectroscopic changes were only observed for the formation of the dicyano complex, [(CN)(2)FePc(SC4H9)(8)](2-). This complex is formed with equilibrium constants, K, of (6.8 +/- 0.8) x 10(2) dm(3) mol(-1) in DMF and (1.3 +/- 0.2) x 10(3) dm(3) mol(-1) in DMSO. Pseudo-first-order rate constants, k(4r), were also estimated to be (1.9 +/- 0.1) x 10(-2) and (8.2 +/- 0.3) x 10(-2) dm(3) mol(-1) s(-1) in DMF and DMSO, respectively. These results agree with the weak electron-donating properties of the peripheral butylthio-substituents on the phthalocyanine ring and the O-bonded trans DMF.