BIS(LIGAND) RHENIUM(V) AND TECHNETIUM(V) COMPLEXES OF 2 NATURALLY-OCCURRING BINDING MOIETIES (OXAZOLINE AND THIAZOLINE)

Attempts to prepare tris(ligand) metal complexes of technetium in inte rmediate oxidation states with potentially bidentate oxazoline- and th iazoline-containing ligands were unsuccessful; when pertechnetate was reduced in the presence of excess ligand, TcO2 . xH(2)O was produced. Instead, by reaction with preformed M . O cores, a series of oxotechne tium(V) and oxorhenium(V) complexes of the formula MOXL(2) (M = Re, X = Br; M = Tc, X = Cl) and HL = 2-(2'-hydroxyphenyl)-2-oxazoline (Hot), 2-(2'-hydroxy-3'-methylphenyl)-2-oxazoline (Hmoz), 2-(2'-hydroxypheny l)-2-thiazoline (Hthoz), and 2-(2'-hydroxyphenyl)-2-benzoxazoline (Hhb o) have been prepared. These compounds have been characterized by a va riety of techniques including single-crystal X-ray diffraction. Crysta ls of Hthoz (C9H9NOS) are monoclinic, with space group P2(1)/n, a = 7. 5342(6) Angstrom, b = 12.2187(6) Angstrom, c = 9.3942(8) Angstrom, bet a = 94.233(7)degrees, and Z = 4; those of TcOCl(thoz)(2) (C18H16CIN2O3 S2Tc) are monoclinic, with space group P2(1)/n, a = 16.506(1)Angstrom, b = 7.664(1) Angstrom, 16.3216(6) Angstrom. beta = 111.154(4)degrees. and Z = 4; those of ReOBr(oz)(2) (C18H16BrN2O5Re) are orthorhombic, w ith space group Pbca, a = 12.864(2) Angstrom, b = 25.369(2) Angstrom, c = 11.025(2) Angstrom, and Z = 8. The structures were solved by direc t (Hthoz) or Patterson (metal complexes) methods and were refined by f ull-matrix Last-squares procedures to R = 0.033, 0.032, and 0.028 for 1600, 3152, and 2651 reflections with I greater than or equal to 3 sig ma(I), respectively. In the two complexes, the geometry around the met als is distorted octahedral with the halide ligands in each bound cis, and one phenolate oxygen from one ligand in each bound trans to the m etal-ore linkage. In ReOBr(oz)(2), the two oxazoline nitrogens are coo rdinated trans to one another; in TcOCl(thoz)(2), the two thiazoline n itrogens are found cis to one another.