| Abstract |
New (E/Z)-2-(2-(1-cyano-2-methoxy-2-oxoethylidene)hydrazinyl)benzoic acid (H2L4) and known sodium 2-(2-(dicyanomethylene)hydrazinyl)benzenesulfonate (NaHL1), 2-(2-(dicyano-methylene)hydrazinyl)benzoic acid (H2L2), and sodium (E/Z)-2-(2-(1-cyano-2-methoxy-2-oxoethylidene)hydrazinyl)benzenesulfonat e (NaHL3) were used in the template synthesis of a series of CuII and CoII complexes [Cu(H2O)(2)L-1a].H2O (1), [Cu(H2O)(3-pyon)L-1b].H2O (2), [Cu(H2O)(4-pyon)L-1b] (3), [Co(H2O)((CH3)(2)NCHO)(mu-L-2a)](2).(CH3)(2)NCHO (4), [Cu-3(mu 3-OH)(NO3)(CH3OH)(mu(2)-X)3(mu(2)-HL3)] (5), [Cu(H2O)(py)L-3].H2O (6), [Cu(H2O)2(mu-L-4)](6).6H(2)O (7), [Cu(2-cnpy(b))2(L-1b)2].2H(2)O (8), [Cu(2-cnpy(a))2(L-1a)2].2H(2)O (9), and [Cu(H2O)(4-cnpy)(L-1a)2] (10), where 3-pyon = 1-(pyridin-3-yl)ethanone, 4-pyon = 1-(pyridin-4-yl)ethanone, py = pyridine, HX = syn-2-pyridinealdoxime, 4-cnpy = 4-cyanopyridine; 2-cnpya, 2-cnpyb, L-1a, L-1b, L-2a are the ligands derived from nucleophilic attack of methanol (a) or water (b) on a cyano group of 2-cyanopyridine (2-cnpy), L-1 or L-2, respectively, giving the corresponding iminoesters (2-cnpya, L-1a or L-2a) or carboxamides (2-cnpyb or L-1b). An auxiliary ligand, namely syn-2-pyridinealdoxime or pyridine, acting cooperatively with the metal ion (CuII in this case), induced an E/Z isomerization of the H2L4 ligand; the E- and Z-isomers were isolated separately and fully characterized (compounds 9 and 10, respectively). A one-pot activation of nitrile groups in different molecules was achieved in the syntheses of 8 and 9. Complexes 110 are catalyst precursors for the solvent-free microwave (MW)-assisted selective oxidation of secondary alcohols to the corresponding ketones, with typical yields in the 2999\% range (TOFs up to 4.94 x 103 h1) after 30 min of MW irradiation. |
