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

Shedding Light on the Single-Molecule Magnet Behavior of Mononuclear Dy^III Complexes

General requirements for obtaining Dy^III single-molecule magnets (SMM) were studied by CASSCF+RASSI calculations on both real and model systems. A set of 20 Dy^III complexes was considered using their X-ray crystal structure for our calculations. Theoretical results were compared with their experimental slow relaxation data, and general conclusions about the calculated key parameters related with SMM behavior are presented. The effect of the coordination geometry and nature of ligands is discussed based on calculations on real and model systems. We found two different patterns to exhibit SMM behavior: the first one leads to the largest axial anisotropy in complexes showing heterolepticity of the ligand environment (more important than symmetric requirements), while the second one corresponds to sandwich-shaped complexes with a smaller anisotropy. Thus, most existing mononuclear zero-field SMMs adopting a heteroleptic coordination mode mixing neutral and anionic ligands present the same pattern in the electrostatic potential induced by their ligands, with a lower potential island related to the presence of neutral ligands inside a high potential background related with anionic groups. The existence of different electrostatic regions caused by the ligands induces a preferential orientation to reduce the electron repulsion for the electron density of the Dy^III cations, resulting in the magnetic anisotropy

Coherent Transport through Spin-Crossover Single Molecules

Coherent quantum transport calculations were performed for high- and low-spin states of a mononuclear Fe^II complex showing spin-crossover behavior using density functional theory methods combined with the non-equilibrium Green functions procedure. The high-spin state has a larger conductivity than the low-spin state; furthermore, it behaves as a spin filter, giving a β-polarized current

Theoretical Modeling of the Ligand-Tuning Effect over the Transition Temperature in Four-Coordinated Fe^II Molecules

Spin-crossover molecules are systems of great interest due to their behavior as molecular level switches, which makes them promising candidates for nanoscale memory devices, among other applications. In this paper, we report a computational study for the calculation of the transition temperature (<i>T</i>_1/2), a key physical quantity in the characterization of spin-crossover systems, for the family of tetracoordinated Fe^II transition-metal complexes of generic formula [PhB­(MesIm)₃­FeNPR₁R₂R₃]. Our calculations correctly reproduce the experimentally reported decrease in the <i>T</i>_1/2 with an increasing size of the phosphine and allow for the prediction of the <i>T</i>_1/2 in new members of the family that are not reported so far. More importantly, further insight into the factors that control the fine-tuning of the <i>T</i>_1/2 can be obtained by direct analysis of the underlying electronic structure in terms of the relevant molecular orbitals

Electronic and Steric Control of the Spin-Crossover Behavior in [(Cp^R)₂Mn] Manganocenes

A computational study of the spin-crossover behavior in the family [(Cp^R)₂Mn] (R = Me, ^<i>i</i>Pr, ^<i>t</i>Bu) is presented. Using the OPBE functional, the different electronic and steric effects over the metal’s ligand field are studied, and trends in the spin-crossover-temperature (<i>T</i>_1/2) behavior are presented in terms of the cyclopentadienyl (Cp) ligand functionalization. Our calculations outlined a delicate balance between both electronic and steric effects. While an increase in the number of electron-donating groups increases the spin-crossover temperature (<i>T</i>_1/2) to the point that the transition is suppressed and only the low-spin state is observed, steric effects play an opposite role, increasing the distance between the Cp rings, which in turns shifts <i>T</i>_1/2 to lower values, eventually stabilizing the high-spin state. Both effects can be rationalized by exploring the electronic structure of such systems in terms of the relevant d-based molecular orbitals

Structures, Magnetochemistry, Spectroscopy, Theoretical Study, and Catechol Oxidase Activity of Dinuclear and Dimer-of-Dinuclear Mixed-Valence Mn^IIIMn^II Complexes Derived from a Macrocyclic Ligand

The work in this paper presents syntheses, characterization, magnetic properties (experimental and density functional theoretical), catecholase activity, and electrospray ionization mass spectroscopic (ESI-MS positive) studies of two mixed-valence dinuclear Mn^IIIMn^II complexes, [Mn^IIIMn^IIL­(μ-O₂CMe)­(H₂O)₂]­(ClO₄)₂·H₂O·MeCN (<b>1</b>) and [Mn^IIIMn^IIL­(μ-O₂CPh)­(MeOH)­(ClO₄)]­(ClO₄) (<b>2</b>), and a Mn^IIIMn^IIMn^IIMn^III complex, [{Mn^IIIMn^IIL­(μ-O₂CEt)­(EtOH)}₂(μ-O₂CEt)]­(ClO₄)₃ (<b>3</b>), derived from the Robson-type macrocycle H₂L, which is the [2 + 2] condensation product of 2,6-diformyl-4-methylphenol and 2,2-dimethyl-1,3-diaminopropane. In <b>1</b> and <b>2</b> and in two Mn^IIIMn^II units in <b>3</b>, the two metal centers are bridged by a bis­(μ-phenoxo)-μ-carboxylate moiety. The two Mn^II centers of the two Mn^IIIMn^II units in <b>3</b> are bridged by a propionate moiety, and therefore this compound is a dimer of two dinuclear units. The coordination geometry of the Mn^III and Mn^II centers are Jahn–Teller distorted octahedral and distorted trigonal prism, respectively. Magnetic studies reveal weak ferro- or antiferromagnetic interactions between the Mn^III and Mn^II centers in <b>1</b> (<i>J</i> = +0.08 cm^–1), <b>2</b> (<i>J</i> = −0.095 cm^–1), and <b>3</b> (<i>J</i>₁ = +0.015 cm^–1). A weak antiferromagnetic interaction (<i>J</i>₂ = −0.20 cm^–1) also exists between the Mn^II centers in <b>3</b>. DFT methods properly reproduce the nature of the exchange interactions present in such systems. A magneto-structural correlation based on Mn–O bridging distances has been proposed to explain the different sign of the exchange coupling constants. Utilizing 3,5-di-<i>tert</i>-butyl catechol (3,5-DTBCH₂) as the substrate, catecholase activity of all the three complexes has been checked in MeCN and MeOH, revealing that all three are active catalysts with <i>K</i>_cat values lying in the range 7.5–64.7 h^–1. Electrospray ionization mass (ESI-MS positive) spectra of the complexes <b>1</b>–<b>3</b> have been recorded in MeCN solutions, and the positive ions have been well characterized. ESI-MS positive spectrum of complex <b>1</b> in presence of 3,5-DTBCH₂ has also been recorded, and a positive ion, [Mn^IIIMn^IIL­(μ-3,5-DTBC^2–)]⁺, having most probably a bridging catecholate moiety has been identified

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

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

Ferro- to Antiferromagnetic Crossover Angle in Diphenoxido- and Carboxylato-Bridged Trinuclear Ni^II₂–Mn^II Complexes: Experimental Observations and Theoretical Rationalization

Three new trinuclear heterometallic Ni^II–Mn^II complexes have been synthesized using a [NiL] metalloligand, where H₂L = <i>N,N</i>′-bis­(salicylidene)-1,3-propanediamine. The complexes [(NiL)₂Mn­(OCnn)₂(CH₃OH)₂]·CH₃OH (<b>1</b>), [(NiL)₂Mn­(OPh)₂(CH₃OH)₂]­[(NiL)₂Mn­(OPh)₂]·H₂O (<b>2</b>), and [(NiL)₂Mn­(OSal)₂(CH₃OH)₂]·2­[NiL] (<b>3</b>) (where OCnn = cinnamate, OPh = phenylacetate, OSal = salicylate) have been structurally characterized. In all three complexes, in addition to the double phenoxido bridge, the two terminal Ni^II atoms are linked to the central Mn^II by means of a <i>syn-syn</i> bridging carboxylate, giving rise to a linear structure. Complexes <b>1</b> and <b>2</b> with Ni–O–Mn angles of 97.24 and 96.43°, respectively, exhibit ferromagnetic interactions (<i>J</i>_Ni–Mn = +1.38 and +0.50 cm^–1, respectively), whereas <b>3</b> is antiferromagnetic (<i>J</i>_Ni–Mn = −0.24 cm^–1), having an Ni–O–Mn angle of 98.51°. DFT calculations indicate that there is a clear magneto-structural correlation between the Ni–O–Mn angle and <i>J</i>_Ni–Mn values, which is in agreement with the experimental results