Syntheses and properties of Re(III) complexes derived from hydrotris(I-pyrazolyl)methanes:: molecular structure of [ReCl2(HCpz3)(PPh3)][BF4]

The complexes [ReCl2{N2C(O)Ph}(Hpz)(PPh3)(2)] (1) (Hpz = pyrazole), [ReCl2{(N2CO)Ph}(Hpz)(2)(PPh3)] (2), [ReCl2(HCpz(3))(PPh3)][BF4] (3) and [ReCl2(3,5-MeHpz)(3)(PPh3)]Cl (4) were obtained by treatment of the chelate [ReCl2{eta(2)-N,O-N2C(O)Ph}(PPh3)(2)] (0) with hydrotris(1-pyrazolyl)methane HCpz(3) (1,3), pyrazole Hpz (1,2), hydrotris(3,5-dimethyl-1-pyrazolyl)methane HC(3,5-Me(2)pz)(3) (4) or dimethylpyrazole 3,5-MeHpz (4). Rupture of a C(sp(3))-N bond in HCpz(3) or HC(3,5-Me(2)pz)(3), promoted by the Re centre, has occurred in the formation of 1 or 4, respectively. All compounds have been characterized by elemental analyses, IR and NMR spectroscopy, FAB-MS spectrometry, cyclic voltammetry and, for 1 center dot CH2O2 and 3, also by single crystal X-ray analysis. The electrochemical E-L Lever parameter has been estimated, for the first time, for the HCpz(3) and the benzoyldiazenide NNC(O)Ph ligands. (c) 2004 Elsevier B.V. All rights reserved.