REDOX-SWITCHED BONDING OF PROTONS TO FERROCENOPHANES, FERROCENE CRYPTANDS, AND SIMPLE FERROCENE AMINES - CORRELATION OF X-RAY STRUCTURAL DATA AND CYCLIC VOLTAMMETRY DERIVED REDOX POTENTIALS

To gain a better understanding of the redox-switched bonding of cation s to ferrocene crown ethers, the redox potentials of 22 ferrocene nitr ogen compounds, including protonated and methylated congeners, were de termined. The redox potentials of the ammonium salts are shifted by be tween +110 and +600 mV relative to those of the neutral ferrocenes. Me thylation consistently gives slightly larger positive shifts than prot onation. The syntheses and X-ray crystal structures of diprotonated yl ene)]bis(N-7-aza-2,3-benzo-1,4-dioxacyclononane) (orthorhombic, Pbca; a = 11.492(2) angstrom, b = 16.034(3) angstrom, c = 18.030(4) angstrom ; V = 3322.3(11) angstrom3; R indices [4(sigma)I] R1 = 4.39%, wR2 = 11 .5%), methylated N-methyl-2-aza-[3]-1,1'-ferrocenophane (monoclinic P2 (1)/c; a = 8.396(2) angstrom, b = 12.336(2) angstrom, c = 13.414(3) an gstrom, beta = 95.16(3)-degrees, V = 1383.7(5) angstrom3; R indices [4 (sigma)I] R1 = 2.86%, wR2 = 7.53%), and dimethylated ene))-1,4,10,13-t etraoxa-7,16-diazacyclooctadecane (triclinic P1BAR; a = 10.522(2) angs trom, b = 12.664(3) angstrom, c = 13.374(3) angstrom, alpha = 82.25(3) -degrees, beta = 76.33(3)-degrees, gamma = 78.82(3)-degrees; V = 1691. 3(6) angstrom3; R indices [4(sigma)I] R1 = 5.19%, wR2 = 15.4%) are des cribed. The solid state structural data and the cyclic voltammetry der ived redox potentials illustrate a linear relationship (y = -2.7 + 2.1 x) x 10(2)) between the inverse iron-nitrogen separation (x) and the s hifts of the redox potentials (y) and allow the unambiguous assignment of the structures of the protonated isomers of ne))-1,4,10,13-tetraox a-7,16-diazacyclooctadecane.