Unusual Metalloporphyrin Complexes of Rhenium and Technetium
TEXAS A AND M UNIV COLLEGE STATION DEPT OF CHEMISTRY
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Monometallic and bimetallic porphyrin complexes of rhenium and technetium were synthesized. Visible spectroscopy indicates that first the monometallic and then the bimetallic porphyrin complex is formed. The monometallic complex of rhenium can further react with either Re2CO10 or Tc2CO10 to form the homo- and heterodinuclear metalloporphyrin complexes. Structural data for the homodinuclear metalloporphyrin complexes of both rhenium and technetium were obtained by single crystal X-ray diffraction. Both the rhenium and technetium homodinuclear porphyrins are centrosymmetric complexes having two metals bonded to the porphyrin, one above and one below the plane of the macrocycle while the porphyrin macrocycle is highly distorted. Proton magnetic resonance spectra gave evidence for the proposed structures. A fluxional character of both Re and Tc monometallic porphyrin complexes was observed by variable-temperature pmr spectral studies. A novel thermal disproportionation of H-MPTcCO3 was also observed.
- Organic Chemistry