Abstract
Well structurally characterized bis(mu-halo)-bis[(diamine)copper(I)] complexes [LCuX](2); L = TMED, tetramethylethylenediamine, X = Cl, Br or I and L = TEED, tetraethylethylenediamine, or TMPD, tetramethylpropane-diamine, X = Cl, react quantitatively with tetrachloro-1,2-benzoquinone (TClBQ) as two electron oxidizing agent in O-2-free CH2Cl2 or PhNO2 to form a dimeric [LCuX](2)Cat (Cat = catechol) as indicated by cryoscopic measurements. Infrared spectra was in agreement with total reduction of TClBQ to the corresponding catechol. Electronic spectra indicated a dimeric distorted five coordinate Cu(II) and EPR spectra suggested a square pyramidal arrangement around the Cu(II) centers in [LCuX](2)Cat. The ligand field strength for diamine ligand was higher for the five member chelating ring (TMED) relative to the six membered one (TMPD). Electrochemical reduction of Cu centers in [LCuX](2)Cat were irreversible and occurred at a less negative potential when X = I.