SYNTHESIS AND CHARACTERIZATION OF ALKYLALUMINUM AND ALKYLGALLIUM DERIVATIVES OF 2-(METHYLTHIO) AND 2-METHOXYPHENOL - CRYSTAL-STRUCTURES OF THE DIMERIC COMPLEXES [R2M(MU-OC6H4-2-ECH3)]2 (M=AL, E=S, R=ME, ISO-BU, M=AL, E=O, R=ET, ISO-BU, M=GA, E=O, R=ME) FEATURING 5-COORDINATE METAL CENTERS

2-(Methylthio)- and 2-methoxyphenol react in a 1:1 ratio with trialkylaluminum derivative R3Al (R = Me, Et, i-Bu) or trimethylgallium to yield [R2M(mu-OC6H4-2-ECH3)]2 species (M = Al, E = S, R = Me (1a), Et (1b), i-Bu (1c); M = Al, E = O, R = Me (2a), Et (2b), i-Bu (2c); M = Ga, E = O, R = Me (3)) and the corresponding alkane, RH, in high yield. The resulting phenoxides have been characterized by H-1 and C-13 NMR spectroscopy, and the structures of 1a, 1c, 2b, 2c, and 3 were determined by single-crystal X-ray diffraction techniques. 1a was assigned to the triclinic cell system, space group P1BAR (No. 2), with cell constants a = 9.828 (2) angstrom, 6 = 13.547 (2) angstrom, c = 14.164 (2) angstrom, alpha = 62.15 (1)-degrees, beta = 87.26 (1)-degrees, gamma = 75.05 (2)-degrees, and Z = 3 (dimers). The structure was refined to a final R = 6.20% (R(w) = 6.33%) based on 2735 (F(o) greater-than-or-equal-to 3.0-sigma(F)) observed reflections. 1c was assigned to the triclinic cell system, space group P1BAR (No. 2), with cell constants a = 9.408 (2) angstrom, b = 9.796 (4) angstrom, c = 10.509 (5) angstrom, alpha = 83.66 (4)-degrees, beta = 68.69(3)-degrees, gamma = 66.07 (3)-degrees, and Z = 1 (dimer). The structure was refined to a final R = 3.5% (R(w) = 3.8%) based on 1563 (F(o) greater-than-or-equal-to 3.0-sigma(F)) observed reflections. 2b was assigned to the monoclinic cell system, space group P2(1)/n (No. 14), with cell constants a = 7.9733 (9) angstrom, b = 9.3984 (8) angstrom, c = 15.935 (1) angstrom, beta = 101.06 (1)-degrees, and Z = 2 (dimers). The structure was refined on 1232 (F(o) greater-than-or-equal-to 3.0-sigma(F)) observed reflections to a final R = 3.83% (R(w) = 4.15%). 2c was assigned to the monoclinic cell system, space group P2(1)/c (No. 14), with cell constants a = 9.037 (2) angstrom, b = 19.427 (3) angstrom, c = 9.332 (2) angstrom, beta = 100.71 (1)-degrees, and Z = 2 (dimers). The structure was refined to a final R = 3.52% (R(w) = 3.47%) based on 1808 (F(o) greater-than-or-equal-to 3.0-sigma(F)) observed reflections. 3 crystallizes in the orthorhombic cell system, space group P(cab) (nonstandard setting of space group No. 61), with cell constants a = 6.845 (2) angstrom, b = 15.994 (6) angstrom c = 18.722 (6) angstrom, and Z = 4 (dimers). The structure was refined to a final R = 4.32% (R(w) = 4.62%) based on 1022 (F(o) greater-than-or-equal-to 3.0-sigma(F)) observed reflections. The 2-(methylthio)- and 2-methoxyphenyl groups in the dimer are in the same plane as the Al2O2 ring and are oriented in an anti fashion with respect to one another. The Al-S distances in 1a and 1c are long with an average value of 2.76 angstrom, comparable to those found in simple addition compounds. The molecular units of 2b, 2c, and 3 are similar. In the case of the aluminum complexes, 2b and 2c, the average Al-O coordinate bond distance is 2.25 angstrom. For the gallium complex, 3, the Ga-O coordinate bond distance is 2.52 angstrom. Examination of the variable-temperature NMR spectra of 1a, 2b, and 3 shows no dramatic changes occur as a result of change in temperature. However, the chemical shifts of both the metal alkyl groups and of the ER units change in a linear fashion. This is interpreted in terms of rapid rotation on the NMR time scale of the -C6H4-2-EMe group around the O-C bond. The observed chemical shift is a weighted average of the ''free- and -bound' species.