Ga. Ardizzoia et al., PYRAZOLATO METAL-COMPLEXES - SYNTHESIS, CHARACTERIZATION AND X-RAY CRYSTAL-STRUCTURES OF RHENIUM(I) DERIVATIVES, EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, (10), 1998, pp. 1503-1511
The mononuclear complexes [Re(CO)(3)(Hpz)(2)Br] (1) and [Re(CO)(3)(Hdm
pz)(2)Br] (2) were obtained by treating [Re(CO)(5)Br] with pyrazole (H
pz) or 3,5-dimethylpyrazole (Hdmpz). Complex 1 reacted with triethylam
ine affording a mixture of the ionic dinuclear derivative (Et3NH)[Re-2
(CO)(6)(pz)(2)Br] (3) and of the mononuclear species [Re(CO)(3)(Hpz)(2
)(pz)] (4). Complex 4 was obtained in a pure form by carrying out the
reaction in the presence of excess free pyrazole. Treatment of 4 with
pyridine afforded the [Re(CO)(3)(py) (Hpz)(pz)] species (6). The analo
gues of 4 and 6 with Hdmpz, i.e. [Re(CO)(3)(Hdmpz)(2)(dmpz)] (7) and [
Re(CO)(3)(py) (Hdmpz)(dmpz)] (8) were also synthesized. All species we
re characterized in solution by H-1-NMR spectroscopy, while the crysta
l structures of complexes 1, 3, 4 and 6 were determined by single-crys
tal X-ray diffraction analysis. The [(CO)(3)Re(mu-pz)(2)(mu-Br)Re(CO)3
](-) anion represents the first structurally characterized species con
taining rhenium(I) atoms bridged by mu-pyrazolate ligands.