摘要:
A series of neutral salicylaldiminato MID complexes, Pd(Me)(Ph-CH=N-R')[3-Bu-t-2-(O)C6H3-CH=N-2,6-di-Pr-i-C6H3] (R = CH3, n-Pr, tert-Bu, Ph, benzyl) (3a-3e) and Pd(Me)[2(CH=N-t-Bu)-Py][3-Bu-t-2-(O)C6H3-CH=N-2,6-di-Pr-i-C6H: I (4), have been synthesized and characterized. The structures of complexes 3a, 3c-3e, and 4 have been confirmed by X-ray analysis. NMR studies utilizing 3c indicate that the insertion of CO into the Pd-Me bond occurs through a five-coordinate intermediate. The acyl compounds in turn undergo imine insertion. The neutral complexes 3a-3e show moderate catalytic activity for the polymerization of methyl acrylate at ambient temperature. However, a radical rather than vinyl insertion mechanism appears to be operative.