GROUP-13 TETRAAZAMACROCYCLIC COMPLEXES - THE SYNTHESIS AND CHARACTERIZATION OF THE MONOMETHYL-ALUMINUM(III) AND DIMETHYL-ALUMINUM(III) AND GALLIUM(III) COMPLEXES OF THE 2 TETRAAZAMACROCYCLIC LIGANDS OMTAA(2-) 5,9,14,18-TETRAAZA-DIBENZO[A,H]-CYCLOTETRADECENE), AND TMTAA(2-) -5,9,14,18-TETRAAZA-DIBENZO[A,H]CYCLOTETRADECENE), AND THE CRYSTAL-STRUCTURE OF [MEGA(OMTAA)]

Reactions of the tetraazamacrocyclic ligands H(2)tmtaa (I) and H(2)omt aa (II) with AlMe(3) and GaMe(3) give the dimethyl metal complexes [M( 2)Al(Htmtaa)] (III) and [Me(2)Ga(Homtaa)] (IV), respectively. On heati ng, (III) and (IV) lose an additional molecule of methane to form quan titatively the respective monomethyl derivatives [MeAl(tmtaa)] (V) and [MeGa(omtaa)] (VI). These new macrocyclic complexes have been charact erised by H-1 and C-13 NMR, by FAB mass spectrometry and by elemental analyses. A single crystal X-ray diffraction study of VI reveals a fiv e coordinate square-pyramidal coordination geometry, and the usual sad dle-shape observed for this type of ligand. The gallium(III) lies 0.65 6(1) Angstrom above the mean plane of the four nitrogen atoms, with Ga -C 1.966(3) and Ga-N (average) 2.03(1) Angstrom.