Synthesis, characterization and study of the redox properties of rhenium(V) diolates

Rhenium(V) diolate complexes of the type [ReO(diolate){eta(3)-B(pz)(4)}] (diolate=OCH(CH3)CH2O2- (3), OCH(CH3)CH(CH3)O2- (4), OC(CH3)(2)C(CH3)(2)O2- (5), OCH2CH2CH2O2- (6), OC6H10O2- (7) and OCH2CH2CH2CH2O2- (8)) have been obtained by reacting [ReO{eta(3)-B(pz)(4))(OMe)(2)] (1) with the corresponding diols, in CH2Cl2, or by one-step preparation using [ReOCl3(PPh3)(2)], K[B(pz)(4)] and the respective diols. These compounds have been characterized by elemental analyses, IR, H-1 NMR spectroscopy and, in some cases, by mass spectrometry. The redox properties of these and related complexes were studied by cyclic voltammetry and by controlled potential electrolysis. The synthesis and characterization of the paramagnetic complex [ReCl3{eta(3)-B(pz)(4)}] (11) isolated during these studies is also described, as well as the X-ray structural analysis of 1: monoclinic space group P2(1)/c with cell parameters n=10.539(2), b=13.556(2), c=12.153(2) Angstrom, beta=92.04(2)degrees, V=1735.2(5) Angstrom(3), Z=4. (C) 1998 Elsevier Science S.A.