Nose Structure Delineation of Bouguer Anomaly as the Interpretation Basis of Probable Hydrocarbon Traps: a Case Study on the Mainland Area of Northwest Java Basin

DOI: 10.17014/ijog.v7i3.144Two important aspects in the exploration of oil and gas are technology and exploration concepts, but the use of technology is not always suitable for areas with geological conditions covered by young volcanic sediments or limestone. The land of the Northwest Java Basin is mostly covered by young volcanic products, so exploration using seismic methods will produce less clear image resolution. To identify and interpret the subsurface structure and the possibility of hydrocarbon trap, gravity measurements have been carried out. Delineation of nose structures of a Bouguer anomaly map was used to interpret the probability of hydrocarbon traps. The result of the study shows that the gravity anomalies could be categorized into three groups : low anomaly (< 34 mgal), middle anomaly (34 - 50 mgal), and high anomaly (> 50 mgal). The analysis of Bouguer anomaly indicates that the low anomaly is concentrated in Cibarusa area as a southern part of Ciputat Subbasin, and in Cikampek area. The result of delineation of the Bouguer anomaly map shows the nose structures existing on Cibinong-Cileungsi and Pangkalan-Bekasi Highs, while delineation of residual anomaly map shows the nose structures occurs on Cilamaya-Karawang high. Locally, the gas fields of Jatirangon and Cicauh areas exist on the flank of the nose structure of Pangkalan-Bekasi High, while the oil/gas field of Northern Cilamaya is situated on the flank of the nose structure of Cilamaya-Karawang High. The concept of fluid/gas migration concentrated on nose structures which are delineated from gravity data can be applied in the studied area. This concept needs to be tested in other oil and gas field areas

Mononuclear Single-Molecule Magnets: Tailoring the Magnetic Anisotropy of First-Row Transition-Metal Complexes

Magnetic anisotropy is the property that confers to the spin a preferred direction that could be not aligned with an external magnetic field. Molecules that exhibit a high degree of magnetic anisotropy can behave as individual nanomagnets in the absence of a magnetic field, due to their predisposition to maintain their inherent spin direction. Until now, it has proved very hard to predict magnetic anisotropy, and as a consequence, most synthetic work has been based on serendipitous processes in the search for large magnetic anisotropy systems. The present work shows how the property can be predicted based on the coordination numbers and electronic structures of paramagnetic centers. Using these indicators, two Co^II complexes known from literature have been magnetically characterized and confirm the predicted single-molecule magnet behavior

Huge Magnetic Anisotropy in a Trigonal-Pyramidal Nickel(II) Complex

The work presented herein shows the experimental and theoretical studies of a mononuclear nickel­(II) complex with the largest magnetic anisotropy ever reported. The zero-field-splitting <i>D</i> parameter, extracted from the fits of the magnetization and susceptibility measurements, shows a large value of −200 cm^–1, in agreement with the theoretical value of −244 cm^–1 obtained with the CASPT2–RASSI method

Mononuclear Single-Molecule Magnets: Tailoring the Magnetic Anisotropy of First-Row Transition-Metal Complexes

Magnetic anisotropy is the property that confers to the spin a preferred direction that could be not aligned with an external magnetic field. Molecules that exhibit a high degree of magnetic anisotropy can behave as individual nanomagnets in the absence of a magnetic field, due to their predisposition to maintain their inherent spin direction. Until now, it has proved very hard to predict magnetic anisotropy, and as a consequence, most synthetic work has been based on serendipitous processes in the search for large magnetic anisotropy systems. The present work shows how the property can be predicted based on the coordination numbers and electronic structures of paramagnetic centers. Using these indicators, two Co^II complexes known from literature have been magnetically characterized and confirm the predicted single-molecule magnet behavior

Theoretical Study of Exchange Coupling in 3d-Gd Complexes: Large Magnetocaloric Effect Systems

Polynuclear 3d transition metal-Gd complexes are good candidates to present large magnetocaloric effect. This effect is favored by the presence of weak ferromagnetic exchange interactions that have been investigated using methods based on Density Functional Theory. The first part of the study is devoted to dinuclear complexes, focusing on the nature and mechanism of such exchange interactions. The presence of two bridging ligands is found more favorable for ferromagnetic coupling than a triple-bridged assembly, especially for complexes with small M–O···O–Gd hinge angles. Our results show the crucial role of the Gd 5d orbitals in the exchange interaction while the 6s orbital seems to have a negligible participation. The analysis of the atomic and orbital spin populations reveals that the presence of spin density in the Gd 5d orbital is mainly due to a spin polarization effect, while a delocalization mechanism from the 3d orbitals of the transition metal can be ruled out. We propose a numerical DFT approach using pseudopotentials to calculate the exchange coupling constants in four polynuclear first-row transition metal-Gd complexes. Despite the complexity of the studied systems, the numerical approach gives coupling constants in excellent agreement with the available experimental data and, in conjunction with exact diagonalization methods (or Monte Carlo simulations), it makes it possible to obtain theoretical estimates of the entropy change due to the magnetization/demagnetization process of the molecule

Family of Carboxylate- and Nitrate-diphenoxo Triply Bridged Dinuclear Ni^IILn^III Complexes (Ln = Eu, Gd, Tb, Ho, Er, Y): Synthesis, Experimental and Theoretical Magneto-Structural Studies, and Single-Molecule Magnet Behavior

Seven acetate-diphenoxo triply bridged M^II-Ln^III complexes (M^II = Ni^II and Ln^III = Gd, Tb, Ho, Er, and Y; M^II = Zn^II and Ln^III = Ho^III and Er^III) of formula [M­(μ-L)­(μ-OAc)­Ln­(NO₃)₂], one nitrate-diphenoxo triply bridged Ni^II–Tb^III complex, [Ni­(μ-L)­(μ-NO₃)­Tb­(NO₃)₂]·2CH₃OH, and two diphenoxo doubly bridged Ni^II-Ln^III complexes (Ln^III = Eu, Gd) of formula [Ni­(H₂O)­(μ-L)­Ln­(NO₃)₃]·2CH₃OH have been prepared in one pot reaction from the compartmental ligand <i>N</i>,<i>N</i>′,<i>N</i>″-trimethyl-<i>N</i>,<i>N</i>″-bis­(2-hydroxy-3-methoxy-5-methylbenzyl)­diethylenetriamine (H₂L). Moreover, Ni^II-Ln^III complexes bearing benzoate or 9-anthracenecarboxylate bridging groups of formula [Ni­(μ-L)­(μ-BzO)­Dy­(NO₃)₂] and [Ni­(μ-L)­(μ-9-An)­Dy­(9-An)­(NO₃)₂]·3CH₃CN have also been successfully synthesized. In acetate-diphenoxo triply bridged complexes, the acetate bridging group forces the structure to be folded with an average hinge angle in the M­(μ-O₂)­Ln bridging fragment of ∼22°, whereas nitrate-diphenoxo doubly bridged complexes and diphenoxo-doubly bridged complexes exhibit more planar structures with hinge angles of ∼13° and ∼2°, respectively. All Ni^II-Ln^III complexes exhibit ferromagnetic interactions between Ni^II and Ln^III ions and, in the case of the Gd^III complexes, the <i>J</i>_NiGd coupling increases weakly but significantly with the planarity of the M–(O)₂–Gd bridging fragment and with the increase of the Ni–O–Gd angle. Density functional theory (DFT) theoretical calculations on the Ni^IIGd^III complexes and model compounds support these magneto-structural correlations as well as the experimental <i>J</i>_NiGd values, which were found to be ∼1.38 and ∼2.1 cm^–1 for the folded [Ni­(μ-L)­(μ-OAc)­Gd­(NO₃)₂] and planar [Ni­(H₂O)­(μ-L)­Gd­(NO₃)₃]·2CH₃OH complexes, respectively. The Ni^IIDy^III complexes exhibit slow relaxation of the magnetization with Δ/<i>k</i>_B energy barriers under 1000 Oe applied magnetic fields of 9.2 and 10.1 K for [Ni­(μ-L)­(μ-BzO)­Dy­(NO₃)₂] and [Ni­(μ-L)­(μ-9-An)­Dy­(9-An)­(NO₃)₂]·3CH₃CN, respectively

Family of Carboxylate- and Nitrate-diphenoxo Triply Bridged Dinuclear Ni^IILn^III Complexes (Ln = Eu, Gd, Tb, Ho, Er, Y): Synthesis, Experimental and Theoretical Magneto-Structural Studies, and Single-Molecule Magnet Behavior

Seven acetate-diphenoxo triply bridged M^II-Ln^III complexes (M^II = Ni^II and Ln^III = Gd, Tb, Ho, Er, and Y; M^II = Zn^II and Ln^III = Ho^III and Er^III) of formula [M­(μ-L)­(μ-OAc)­Ln­(NO₃)₂], one nitrate-diphenoxo triply bridged Ni^II–Tb^III complex, [Ni­(μ-L)­(μ-NO₃)­Tb­(NO₃)₂]·2CH₃OH, and two diphenoxo doubly bridged Ni^II-Ln^III complexes (Ln^III = Eu, Gd) of formula [Ni­(H₂O)­(μ-L)­Ln­(NO₃)₃]·2CH₃OH have been prepared in one pot reaction from the compartmental ligand <i>N</i>,<i>N</i>′,<i>N</i>″-trimethyl-<i>N</i>,<i>N</i>″-bis­(2-hydroxy-3-methoxy-5-methylbenzyl)­diethylenetriamine (H₂L). Moreover, Ni^II-Ln^III complexes bearing benzoate or 9-anthracenecarboxylate bridging groups of formula [Ni­(μ-L)­(μ-BzO)­Dy­(NO₃)₂] and [Ni­(μ-L)­(μ-9-An)­Dy­(9-An)­(NO₃)₂]·3CH₃CN have also been successfully synthesized. In acetate-diphenoxo triply bridged complexes, the acetate bridging group forces the structure to be folded with an average hinge angle in the M­(μ-O₂)­Ln bridging fragment of ∼22°, whereas nitrate-diphenoxo doubly bridged complexes and diphenoxo-doubly bridged complexes exhibit more planar structures with hinge angles of ∼13° and ∼2°, respectively. All Ni^II-Ln^III complexes exhibit ferromagnetic interactions between Ni^II and Ln^III ions and, in the case of the Gd^III complexes, the <i>J</i>_NiGd coupling increases weakly but significantly with the planarity of the M–(O)₂–Gd bridging fragment and with the increase of the Ni–O–Gd angle. Density functional theory (DFT) theoretical calculations on the Ni^IIGd^III complexes and model compounds support these magneto-structural correlations as well as the experimental <i>J</i>_NiGd values, which were found to be ∼1.38 and ∼2.1 cm^–1 for the folded [Ni­(μ-L)­(μ-OAc)­Gd­(NO₃)₂] and planar [Ni­(H₂O)­(μ-L)­Gd­(NO₃)₃]·2CH₃OH complexes, respectively. The Ni^IIDy^III complexes exhibit slow relaxation of the magnetization with Δ/<i>k</i>_B energy barriers under 1000 Oe applied magnetic fields of 9.2 and 10.1 K for [Ni­(μ-L)­(μ-BzO)­Dy­(NO₃)₂] and [Ni­(μ-L)­(μ-9-An)­Dy­(9-An)­(NO₃)₂]·3CH₃CN, respectively

A Mn^II₆Mn^III₆ Single-Strand Molecular Wheel with a Reuleaux Triangular Topology: Synthesis, Structure, Magnetism, and DFT Studies

The use of the anion of 3-methyl-1,3,5-pentanetriol (mpt^3–) in manganese carboxylate chemistry has afforded the new Mn^II/III₁₂ cluster [Mn^II₆Mn^III₆(mpt)₆(CH₃CO₂)₁₂(py)₆]·3CH₃CN (<b>1</b>·3CH₃CN). Complex <b>1</b> was isolated in moderate yield by the reaction of Mn­(CH₃CO₂)₂·4H₂O and H₃mpt in a 2.6:1 molar ratio in a solvent mixture of acetonitrile and pyridine. The structure of <b>1</b> consists of alternating [Mn^II₂(CH₃CO₂)₃(py)]⁺ and [Mn^III₂(μ-OR)₂(CH₃CO₂)­(py)]³⁺ dimeric units (three of each dimer), linked at each end by two alkoxo and one acetate bridges; the mpt^3– ligands adopt the η²:η²:η²:μ₄ coordination mode. The overall metal topology of this new Mn₁₂ wheel resembles a guitar plectrum, or a Reuleaux triangle. Complex <b>1</b> displays an unprecedented structural topology, being the first example of a Mn^II₆Mn^III₆ wheel constructed from alternating homovalent dimers and the only known Mn₁₂ loop with the trigonal symmetry of a Reuleaux triangle (all other reported loops were ellipsoids). Variable-temperature, solid-state direct- and alternating-current magnetization studies were carried out on complex <b>1</b>, revealing the presence of antiferromagnetic exchange interactions between the metal ions in the molecule, which lead to a spin ground-state value <i>S</i> = 0; the exchange coupling parameters <i>J</i> were calculated using density functional theory employing a hybrid B3LYP functional