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|Title: ||Monomeric, tetrameric, and polymeric copper di-tert-butyl phosphate complexes containing pyridine ancillary ligands|
|Authors: ||MURUGAVEL, R|
|Keywords: ||ammonium hexaaquacopper(ii) sulfate|
|Issue Date: ||2004|
|Publisher: ||AMER CHEMICAL SOC|
|Citation: ||INORGANIC CHEMISTRY, 43(3), 945-953|
|Abstract: ||The reaction of di-tert-butyl phosphate (((BuO)-Bu-t)(2)P(O)(OH), dtbp-H) with copper acetate in the presence of pyridine (py) and 2,4,6-trimethylpyridine (collidine) has been investigated. Copper acetate reacts with dtbp-H in a reaction medium containing pyridine, DOC, THF, and CH3OH to yield a one-dimensional polymeric complex [Cu(dtbP)(2)(py)(2)(mu-OH2)](n) (1) as blue hollow crystalline tubes. The copper atoms in 1 are octahedral and are surrounded by two terminal phosphate ligands, two pyridine molecules, and two bridging water molecules. The mu-OH2 ligands that are present along the elongated Jahn-Teller axis are responsible for the formation of the one-dimensional polymeric structure. Recrystallization of 1 in a DMSO/THF/CH3OH mixture results in the reorganization of the polymer and its conversion to a more stable tetranuclear copper cluster [Cu-4(mu(3)-OH)(2)(dtbP)(6)(py)(2)] (2) in about 60% yield. The molecular structure of 2 is made up of a tetranuclear core [Cu-4(mu(3)-OH)(2)] which is surrounded by six bidentate bridging dtbp ligands. While two of the copper atoms are pentacoordinate with a tbp geometry, the other two copper atoms exhibit a pseudooctahedral geometry with five normal Cu-O bonds and an elongated Cu-O linkage. The pentacoordinate copper centers bear an axial. pyridine ligand. The short Cu...Cu nonbonded distances in the tetranuclear core of 2 lead to magnetic ordering at low temperature with an antiferromagnetic coupling at similar to20 K (J(p) = -44 cm(-1), J(c) = -66 cm(-1), g = 2.25, and p = 0.8%). When the reaction between di-tert-butyl phosphate (dtbp-H) and copper acetate was carried out in the presence of collidine, large dark-blue crystals of monomeric copper complex [Cu(dtbP)(2)(collidine)(2)] (3) formed as the only product. A single-crystal X-ray diffraction study of 3 reveals a slightly distorted square-planar geometry around the copper atom. Thermogravimetric analysis of 1-3 revealed a facile decomposition of the coordinated ligands and dtbp to produce a copper phosphate material around 500 degreesC. An independent solid-state thermolysis of all the three complexes in bulk at 500-510 degreesC for 2 days produced copper pyrophosphate Cu2P2O7 along with small quantities of Cu(PO3)(2) as revealed by DR-UV spectroscopic and PXRD studies.|
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