Features of a flexible backbone in the coordination compounds of a dioximeligand: The characterization of supramolecular and dinuclear metal complexes

The grinding of a 2:1 molar ratio mixture of isonitrosoacetylacetone and 1, 3-diaminopropan-2-ol led to formation of the tribasic ligand (H3L), (1) wit h two oxime groups and a flexible alcoholic backbone. The 1 :2 molar ratio reaction of (1) with CuX2 produced the planar dinuclear complexes LCu2(X) n H(2)O; X = acetate (2), phenylacetate (3), formate (4), monochloroacetate ( 5), dichloroacetate (6), trichloroacetate (7), benzoate (8), and p-hydroxyb enzoate (9); n = 1 for (2) and (8); n = 2 for (3)-(7); and n=4 for (9). The copper(II) ions are bridged by the carboxylate and the alcoholic oxygen. T he strong antiferromagnetic interactions in (2)-(9) are impeded in (5)-(7) by the chloroacetate bridge withdrawing electron density from the carboxyla te. The latter bridge is replaced by picrate in the 1:1 molar ratio reactio n of (2) with picric acid (10). The 1:1 molar ratio reaction of (1) with co pper(II) acetate produced the tetranuclear [HLCu](2)[LCu2(OAc)] . 5H(2)O (1 1), whereas the 2:1 molar ratio reaction, similar to the reaction which led to (8), produced HLCu (12). The latter complex reacted (1 : 1 molar ratio) with either copper(II) acetate or nickel(II) acetate to produce complexes (2) and the heterodinuclear LNiCu(OAc) . 2H(2)O (13), respectively. Similar reactions with (11) gave the same complexes (2) and (13). The acid adducts of (9) with p-hydroxybenzoic acid (14) and LCu2(X) . HX (15); X = p-aminob enzoic acid were isolated. The cobalt(II) analogue of the mononuclear (12), HLCo . 2H(2)O (16) was obtained from the 1:1 molar reaction of (1) with co balt(II) acetate. The supramolecular structure of (11), (12) and (16) took place via intermolecular hydrogen bonding of the alcoholic proton with the oximato oxygen of the adjacent molecule which mediated electron density and allowed for a magnetic exchange interaction. The suggested structures of t he ligand and metal complexes are in accordance with analytical, spectral a nd magnetic moment data.