A Radical‐Radical and Metal–Metal Coupling Tetrathiafulvalene Derivative in which Organic Radicals Directly Coordinate to Cu II Ions

A new dinuclear metal complex including tetrathiafulvalene (TTF) radicals as ligands has been prepared and characterized, [{DMT‐TTF(CONH 2 ) 2 } 2 Cu 2 Cl 6 ] ( 1 ), DMT‐TTF(CONH 2 ) 2 = o ‐bis(amido)‐appended dimethylthio‐tetrathiafulvalene. The compound is an uncommon example in which TTF radicals directly coordinate to the copper( II ) halide by the amido group. Crystal structure analysis shows that it is a unique coordination bond/H‐bond/S ··· S stacking cooperative system with two radicals and two paramagnetic transition metal ions, TTF + · –Cu II –Cu II –TTF + · . In the structure of 1 , the DMT‐TTF units form dimers with very strong S ··· S interactions. The Cu II –O(amide) distance of the coordination bond is 2.271(2) Å and the S ··· S stacking distances between the radicals are in the range 3.345–3.489 Å. The metal–metal ions are mildly antiferromagnetically coupled (2 J 1 =–58.4 cm –1 ), while the radical pairs are strongly antiferromagnetically coupled (2 J 2 > –1000 cm –1 ).(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)