New molybdenum(V) complexes based on the {Mo2O4}(2+) structural core with esters or anions of malonic and succinic acid

摘要

A series of malonato complexes of molybdenum(V) was prepared by reacting (PyH)(5)[MOOCl4(H2O)](3)Cl-2 or (PyH) [MoOBr4] with malonic acid (H(2)mal) or a half-neutralized acid, hydrogen malonate (Hmal(-)), at ambient conditions: (PyH)(3)[Mo2O4Cl4(mu(2)-Hmal)] CH3CN (1), (PyH)(3)[Mo2O4Br4(mu(2)-Hmal)] center dot CH3CN (2), (PyH)(2)[Mo2O4Cl(eta(2)-mal)(mu(2)-Hmal)Py] (3), (3,5-LutH)(2)(H3O) [Mo2O4(eta(2)-mal)(2)(mu(2)-Hmal)] (4), (PyH)[Mo2O4Cl2(mu(2)-Memal)Py-2] (5), (3,5-LutH)[Mo2O4Cl2(mu(2)-Memal)(3,5-Lut)(2)] (6), (PyH)[Mo2O4Cl2(mu(2)-Etmal)Py-2] (7), (3,5-LutH)[Mo2O4Cl2(mu(2)-Prmal)(3,5-Lut)(2)] (8) and [{Mo2O4(mu(2)-Memal)Py-2}(2)(mu(2)-OCH3)(2)] (9) (where Py=pyridine, C5H5N; PyH+ = pyridinium cation, C5H5NH+; 3,5-Lut = 3,5-lutidine, C7H9N; 3,5-LutH(+) = 3,5-lutidinium cation, C7H9NH+; mal(2-) = malonate, -OOCCH2COO-; Memal(-) = monomethyl malonate, -OOCCH2COOCH3; Etmal(-) = monoethyl malonate, -OOCCH2COOC2H5 and Prmal(-) monopropyl malonate, -OOCCH2COOC2H7 The complex anions of compounds 1-8 have a common structural feature: a dinuclear, singly metal-metal bonded {Mo2O4}(2+) core with the carboxylate moiety of the malonato ligand coordinated in a syn-syn bidentate bridging manner to the pair of metal atoms. The remaining four coordination sites of the {Mo2O4}(2+) core are occupied with halides in 1 and 2, with halides/pyridine ligands in 5-8, with a pair of bidentate malonate ions in 4 and with the combination of all in 3. The neutral molecules of 9 consist of two {Mo2O4}(2+) cores linked with a pair of methoxide ions into a chain-like, tetranuclear cluster. An esterification of malonic acid was observed to take place in the reaction mixtures containing alcohols. Solvothermal reactions with malonic acid carried out at 115 degrees C produced anionic acetato complexes as found in (PyH)[Mo2O4Cl2(mu(2)-OOCCH3)Py-2] (.) Py (10), (PyH)[Mo2O4Cl2(mu(2)-OOCCH3)Py-2] (11), (3,5-LutH)[Mo2O4Cl2(mu(2)-OOCCH3)(3,5-Lut)(2)] (12) and (4-MePyH)(3)[Mo2O4Cl2(mu(2)-OOCCH3)(4-MePy)(2)](2)Cl (13) (4-MePy = 4-methylpyridine, C6H7N). The acetate coordinated in the syn-syn bidentate bridging mode in all. Reactions of (PyH)(5)[MOOCl4(H2O)](3)Cl-2 with succinic acid (H(2)suc) at ambient conditons resulted in a complex with a half-neutralized acid, (PyH)[Mo2O4Cl2(mu(2)-Hsuc)Py-2] center dot Py (14) (Hsuc = hydrogen succinate, -OOC(CH2)(2)COOH), while those carried out at 115 degrees C in a tetranuclear succinato complex, (4-MePyH)(2)[{Mo2O4Cl2(4-MePy)(2)}(2)(mu(4)-suc)] (15) (suc(2-) = succinate, -OOC(CH2)(2)COO-). The tetranuclear anion of 15 consists of two {Mo2O4}(2+) cores covalently linked with a tetradentate succinato ligand. The compounds were fully characterized by infrared vibrational spectroscopy, elemental analyses and X-ray diffraction studies. (c) 2006 Elsevier B.V. All rights reserved.