Redox-active 17- and 19-membered metallamacrocycles incorporating tetrathiafulvalene

Redox-active 17- and 19-membered metallamacrocycles were prepared thanks to the chelating ability of bis[(diphenylphosphane)alkylthio]TTF towards the M(CO)(4) fragment (M = Mo, W). The TTF unit can adopt either a cis or a trans configuration as can the phosphorus atoms coordinated to the metal center. Moreover, an element of planar chirality is generated by the trans isomer of the TTF. Thus, the reaction affords six stereoisomers as evidenced by P-31 NMR and Xray crystallographic analyses. The electrochemical properties of the title compounds have been investigated by cyclic voltammetry. Within the 19-membered metallamacrocycles, no significant influence of the two redox moieties was detected, whereas in the 17-membered metallamacrocycles, the oxidized TTF modifies the redox behavior of the metal center. Two crystalline complexes obtained with tetracyanoquinodimethane (TCNQ) and the tungsten 17- and 19-membered metallamacrocycles are reported. Comparison of the crystal structures shows that these metallamacrocycles appear to be rather flexible even with strained structures.