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Synthesis and Structure of Barium Complex Containing 2, 2, 6, 6-Tetramethyl-3, 5-heptanedionate and 1, 10-Phenanthroline Ligands
Abstract
The title complex Ba (thd) 2(phen) 2 (thd = 2, 2, 6, 6-tetramethyl-2, 5-heptanedionate, phen = 1, 10-phenanthroline) (C 46H 54O 4N 4Ba, M r = 864.29) was prepared by the reaction of barium dichloride dihydrate with 2, 2, 6, 6-tetramethyl-3, 5-hep-tanedione and 1, 10-phenanthroline in DME(DME = MeOCH 2CH 2OMe) and was characterized by X-ray diffraction analysis. The title complex crystallized in monoclinic system, space group P2 1/n (# 14) with a = 12.542(2), b = 19.881(3), c = 18.253(3) Å, β = 105.50(1)°, V = 4385(1) Å 3, Z = 4, D c = 1.309g/cm 3, F(000) = 1784.00, μ = 9.50cm -1, The final R = 0.033 and R w, = 0.043 for 5728 observed reflections with I≥3σ(I). The crystal structure shows the β-diketonate ligand coordinated to barium with a delocalized π bond. The mean bond distances of Ba - N and Ba - O are 2.949 Å and 2.657 Å, respectively.
The complexes of 2-(Pyrazol-1′-yl) pyridine with Ni (II), Pd(II) and Pt (II) are reported. Stability constants were carried out by Job's method of continuous variation. The complexes were characterized on the basis of analytical data for metal determination by atomic absorption, elemental analysis, spectroscopic evidence and qualitative analysis by x-ray diffraction. The ligand forms a 1:1 complex with these metals.
In the molecular structure of the title complex, [Cu(C10H9O2)Cl(C5H14N2)], the CuII atom is in a distorted square-pyramidal geometry, coordinated by two O atoms of a benzoylacetonate ligand and two N atoms of a 3-(dimethylamino)propylamine ligand in the basal plane, while a Cl atom occupies the apical position.
The reaction of barium metal with Hthd in dry pentane results in the tetranuclear complex Ba4(thd)8 (I), which can be sublimed in vacuo. Using Hthd, containing a small amount of pivalic acid, the pentanuclear chelate Ba5(thd)9(piv) (II) was isolated. Crystal structure determination shows the rhomboid arrangement of barium atoms in I and square Ba4 units combined with Ba3 triangles in a common side in II. All thd ligands in I are monochelating and differ only by the number of additional OBa bonds. In structure II, besides this type of coordination, a new bichelating coordination mode of β-diketonate ligands has been found.
The synthetic condition and thermal properties of Ba(DPM)2 (bis-dipivaloylmethanato-barium), Ba(DIVM)2 (bis-diisovalerylmethanato-barium), and Ba(DBM)2 (bis-dibutyrylmethanato-barium) were investigated. It was found from NMR analysis that ligands of DPM, DIVM and DBM could be prepared as intended. The yield values of Ba(DIVM)2 and Ba(DBM)2 were about three times larger than that of Ba(DPM)2. It was clarified from thermal properties measured using thermogravimetry (TG) that volatilization of Ba(DPM)2 was higher than that of Ba(DIVM)2 and Ba(DBM)2, however, melting points of Ba(DIVM)2 and Ba(DBM)2 were slightly lower than that of Ba(DPM)2. The volatilization of Ba(DPM)2, Ba(DIVM)2 and Ba(DBM)2, exposed to the air for only one week, decreased. The stability of Ba(DPM)2(Phen)2, Ba(DIVM)2(Phen)2 and Ba(DBM)2(Phen)2, which were prepared by addition of phenanthroline to Ba(DPM)2, Ba(DIVM)2 and Ba(DBM)2, was superior to that of mother barium chelates.
The title compound consists of an octahedron of barium atoms connected together by dpm and aqua ligands in which the O22− group, bridging the six metal atoms, has a long OO bond.
Several of the beta-diketonate metal complexes used for metal organic chemical vapor deposition (MOCVD) of thin-film superconductors have been characterized by thermogravimetric analysis, mass spectrometry, and gas chromatography/mass spectrometry. The volatility of the alkaline-earth-metal chelates has been studied, and it has been determined that one reason the alkaline-earth-metal chelates are less volatile than other metal beta-diketonates is that they exist as oligomers. For example, one barium beta-diketonate chelate consists of a cluster of five metal ions bridged by beta-diketonate carbonyl oxygens and water molecules. It has also been found that the addition of uncomplexed (protonated) beta-keto enolate ligand to the carrier gas stream greatly improves the gas chromatographic behavior of these alkaline-earth-metal chelates, probably owing to adduct formation accompanying the dissociation of the oligomers. The results of these studies, as well as the implications for using these chelates together with auxiliary ligands for MOCVD, will be discussed.