STRUCTURE OF SO-5,10,15,20-TETRAPHENYLPORPHYRINATO)GALLIUM(III) - GA(TPP)(OAC)

The title compound, Ga(tpp)(OAc), crystallizes in the space group P2(1 )/n with a = 10.628(2), b = 16.176(2), c = 20.750(2) Angstrom, beta = 92.64(2)degrees, and Z = 4. The gallium atom has a square-pyramidal co ordination geometry formed by the four nitrogen atoms of the porphyrin ato group (Np) and the acetate ion. The geometry around the gallium ce nter of the Ga(tpp)(OAc) molecule has Ga-O(1) = 1.874(4) Angstrom and average Ga-Np(porphyrin nitrogen) = 2.056(4) Angstrom. The acetate gro up is unidentately coordinated to the gallium (III) atom. Ga-71 NMR sp ectroscopy provides a complementary method for investigation of the ac etate ligand. Combining the calculated value of tau(c), 29.0 ps, with the measured Ga-71 quadrupolar relaxation time, T-1Q = 11.1 mu s, the quadrupole coupling constant of Ga-71 is 28.1 MHz. This further suppor ts that Ga is covalently coordinated to the acetate and tpp in Ga(tpp) (OAc). The methyl and carbonyl carbons of the acetate group are separa tely located at 20.4 and 168.8 ppm at 24 degrees C for the Ga(tpp)(OAc ).