Pyrazolato metal complexes: Synthesis, characterization and X-ray crystal structures of polynuclear organometallic Re-Mn derivatives

By reacting [Re(CO)(3)(Hpz)(2)(pz)] (Hpz = pyrazole) with [Mn(CO)(5)Br] in toluene in the presence of Et3N, the dinuclear complex [(CO)(3)Re(pz)(3)Mn(CO)(3)](Et3NH) (1) was obtained. The reaction of 1 with molecular oxygen affords the tetranuclear compound [(CO)(3)Re(pz)(3)Mn(O)(3)Mn(pz)(3)Re(CO)(3)](Et3NH)(2) (3) or the trinuclear compound [(CO)(3)Re(pz)(3)Mn(pz)(3)Re(CO)(3)] (Et3NH)(2) (5) depending on the experimental conditions. Complexes 1, 3 and 5 were characterized in the solid state by single crystal X-ray diffraction analysis and were showed to contain Re ... Mn interactions Linked by and tris-mu(2)-pyrazolato bridges. In 5, a short [2.397(4) Angstrom] tris(mu(2)-oxo)bridged Mn-IV-Mn-IV contact is found, leading to strong antiferromagnetic coupling of the d(3) ions. The homometalllic species [(CO)(3)Mn(pz)(3)Mn(CO)(3)]-(Et3NH) (2) was also prepared and found to be isostructural with 1.