The synthesis and properties of some new metallodibenzotetraaza[14]annulenes

Abstract

Several new metallodibenzotetraaza[14]annulenes have been prepared that exhibit unique coordination chemistry. The ligands utilized in these new complexes are 1,8-dihydrodibenzo(b,i)(1,4,8,11)tetraaza[14]-annulene (C₁₈H₁₆N₄ or H₂TAA) and 1,8-dihydro-5,7,12,14-tetramethyl-dibenzo(b,i)(1,4,8,11)tetraaza[14]annulene(C₂₂H₂₄N₄ or H₂TMTAA). Properties of some of these new compounds have been studied. Bimetallic dibenzotetraaza[14]annulene complexes of rhenium have been prepared by the reaction of stoichiometric quantities of Re₂(CO)₁₀ and the ligand in refluxing decalin. These compounds, [Re(CO)₃]₂TAA and [Re(CO)₃]₂TMTAA, were purified via column chromatography. X-ray diffraction studies on [Re(CO)₃]₂TAA show that the tricarbonyl rhenium (I) moieties are on opposite faces of the TAA ligand. The metal-metal interatomic distance is 3.345 Å, and the TAA macrocycle is highly distorted from planarity. Preliminary x-ray results on a [Re(CO)₃]₂TMTAA crystal show that the tricarbonyl rhenium (I) moieties reside on the same side of the TMTAA ligand. The Re-Re interatomic distance is approximately 4.11 Å. ...