Giant Keplerate molecule Fe30 - the first octopole magnet

The multipole expansion technique is applied to one of the largest magnetic molecules, Fe30. The molecule's dipole, toroid and quadrupole magnetic moments are equal to zero (in the absence of magnetic field) so the multipole expansion starts from the octopole moment. Probably the Fe30 molecule is the most symmetrical magnetic body synthesized so far. The magnetization process is considered theoretically in different geometries. Some components of the octopole moment experience a jump while the magnetization rises linearly up to its saturation value. An elementary octopole moment consisting of four magnetic dipoles is proposed as a hint for designing of an experiment for measurement of octopole magnetic moment components.Comment: 7 pages, 9 figure

Mechanistic Study of the Oxidation of a Methyl Platinum(II) Complex with O_2 in Water: Pt^(II)Me-to-Pt^(IV)Me and Pt^(II)Me-to-Pt^(IV)Me_2 Reactivity

The mechanism of oxidation by O_2 of (dpms)Pt^(II)Me(OH_2) (1) and (dpms)Pt^(II)Me(OH)^− (2) [dpms = di(2-pyridyl)methanesulfonate] in water in the pH range of 4–14 at 21 °C was explored using kinetic and isotopic labeling experiments. At pH ≤ 8, the reaction leads to a C_1-symmetric monomethyl Pt^(IV) complex (dpms)Pt^(IV)Me(OH)_2 (5) with high selectivity ≥97%; the reaction rate is first-order in [Pt^(II)Me] and fastest at pH 8.0. This behavior was accounted for by assuming that (i) the O_2 activation at the Pt^(II) center to form a Pt^(IV) hydroperoxo species 4 is the reaction rate-limiting step and (ii) the anionic complex 2 is more reactive toward O_2 than neutral complex 1 (pK_a = 8.15 ± 0.02). At pH ≥ 10, the oxidation is inhibited by OH^– ions; the reaction order in [Pt^(II)Me] changes to 2, consistent with a change of the rate-limiting step, which now involves oxidation of complex 2 by Pt^(IV) hydroperoxide 4. At pH ≥ 12, formation of a C_1-symmetric dimethyl complex 6, (dpms)Pt^(IV)Me_2(OH), along with [(dpms)Pt^(II)(OH)_2]^− (7) becomes the dominant reaction pathway (50–70% selectivity). This change in the product distribution is explained by the formation of a C_s-symmetric intermediate (dpms)Pt^(IV)Me(OH)_2 (8), a good methylating agent. The secondary deuterium kinetic isotope effect in the reaction leading to complex 6 is negligible; k_H/k_D = 0.98 ± 0.02. This observation and experiments with a radical scavenger TEMPO do not support a homolytic mechanism. A S_N2 mechanism was proposed for the formation of complex 6 that involves complex 2 as a nucleophile and intermediate 8 as an electrophile

The first detailed δ¹³С<inf>оrg</inf>record in Permo-Triassic boundary deposits in the Kolyma–Omolon region (Northeast Asia)

© 2017, Pleiades Publishing, Ltd. We have obtained the first detailed δ 13 С org record in Permian-Triassic boundary sediments in deepwater facies in Northeast Asia (Kolyma–Omolon region, Balygychan Basin). Our data show good convergence both with the Setorym River section (South Verkoyansk region), where the Permian-Triassic boundary has been determined approximately, and with a number of other sections of Permian-Triassic boundary sediments in the Boreal and Tethyan Superrealms, in particular, in the Buchanan Lake section in Arctic Canada, the Festningen section on Spitsbergen, the Wadi Shahha section on the Arabian Peninsula, and published sections in the Dolomites

New results of U–Pb SHRIMP dating of zircons from upper Wuchiapingian (Upper Permian) deposits in northeastern Russia

© 2017, Pleiades Publishing, Ltd. The first results are presented for U-Pb SHRIMP-II dating of zircons from the upper part of the Khivachian regional horizon (stage) of the Regional Stratigraphic Scale (RSS) of the Permian in northeastern Russia. The obtained isotope age of 255 ± 2 Ma is close to that of the present boundary between the Wuchiapingian and Changhsingian stages of the Permian system in the International Stratigraphic Scale (254.1 Ma). Based on the distribution of bivalves—Intomodesma spp. and Claraioides aff. primitivus (Yin)—in the sections considered, their relations to the stratigraphic positions of the samples considered and dated formerly, and in view of the interregional correlation of recent δ 13 С org data for clayey rocks, one may assume with certainty that most of the regional zone of Intomodesma costatum corresponds to the upper part of the Wuchiapingian stage. Here, the Changhsingian stage in northeastern Asia complies only with the uppermost part of this zone within the I. postevenicum subzone and, partially, of Otoceras layers within the Otoceras concavum zone

Permian diamictites in northeastern Asia: Their significance concerning the bipolarity of the late Paleozoic ice age

© 2015 Elsevier B.V. Despite a lack of detailed sedimentologic analyses, diamictites in the Middle Permian Atkan Formation were previously interpreted as glaciomarine and glacially-influenced marine deposits. This interpretation allowed this unit to play a prominent role in paleoclimatic and biogeographical reconstructions associated with presumed bipolar glaciation during the late Paleozoic ice age (LPIA). In this sense, the LPIA is considered to be a close analog to bipolar glaciation and climate change during the Cenozoic. Here, results are presented that challenge the glacigenic interpretation for these strata and negate interpretations of the bipolar nature of the LPIA. The 400 to 1500-m-thick Atkan Formation was deposited in back-arc basins associated with activity of the Okhotsk-Taigonos volcanic arc along the leading edge of Pangea as it drifted across the North Polar Circle. The occurrence of tuffs, volcanic clasts, and glass shards indicate derivation from a nearby arc. Cooling and solidification of some clasts during sedimentation is suggested by the occurrence of clasts with embayments and protrusions that extend into the surrounding matrix, clasts with columnar-like jointing, and alteration of the matrix surrounding some clasts. CA-TIMS dating of tuff zircons indicate a late Capitanian age, which is consistent with fossils within the strata. Bedded diamictites deposited as debrites dominate. These diamictites, which occur as tens of m thick downlapping packages that thicken then thin upward, were deposited as prograding and abandoning sediment gravity-flow fans. Chaotic and folded strata formed as slumps. Graded sandstones and conglomerates were deposited as turbidites, and mudstones were deposited as mudflows, low-density turbidites, and hemipelagic deposits. Striated clasts and outsized clasts piercing bedding were not observed in the study area. Strata above and below the Atkan Formation contain abundant graded beds and deep-water trace fossils indicating deposition as turbidites. The combination of debrites, turbidites, slumps, volcanic grains (clasts, glass, and tuffs), and an absence of glacigenic indicators suggest that Atkan strata were deposited in deep-water basins associated with the development of the volcanic arc rather than due to glacial activity. These findings are significant as they require reconsideration of current views of LPIA glaciation and suggest that ice sheets were limited to Gondwana

Mechanism of O_2 Activation and Methanol Production by (Di(2- pyridyl)methanesulfonate)Pt^(II)Me(OH_n)^((2−n)−) Complex from Theory with Validation from Experiment

The mechanism of the (dpms)Pt^(II)Me(OH_n)^((2–n)−) oxidation in water to form (dpms)Pt^(IV)Me(OH)_2 and (dpms)Pt_(IV)Me_2(OH) complexes was analyzed using DFT calculations. At pH 12. The pH-independent Pt-to-Pt methyl transfer involves the isomeric methyl Pt(IV)–OOH species with the methyl group trans to the sulfonate. This methyl Pt(IV)–OOH complex is more stable and more reactive in the Pt-to-Pt methyl-transfer reaction as compared to its isomer with the methyl group trans to the pyridine nitrogen. A similar structure–reactivity relationship is also observed for the S_N2 functionalization to form methanol by two isomeric (dpms)Pt^(IV)Me(OH)_2 complexes, one featuring the methyl ligand trans to the sulfonate group and another with the methyl trans to the pyridine nitrogen. The barrier to functionalize the former isomer with the CH_3 group trans to the sulfonate group is 2–9 kcal/mol lower. The possibility of the involvement of Pt(III) species in the reactions studied was found to correspond to high-barrier reactions and is hence not viable. It is concluded that the dpms ligand facilitates Pt(II) oxidation both enthalpically and entropically

The model and the planning method of volume and variety assessment of innovative products in an industrial enterprise

In the long term, the innovative development strategy efficiency is considered as the most crucial condition for assurance of economic system competitiveness in market conditions. It determines the problem relevance of such justification strategies with regard to specific systems features and conditions of their operation. The problem solution for industrial enterprises can be based on mathematical models of supporting the decision-making on the elements of the innovative manufacturing program. An optimization model and the planning method of innovative products volume and variety are suggested. The feature of the suggested model lies in the nonlinear nature of the objective function. It allows taking into consideration the law of diminishing marginal utility. The suggested method of optimization takes into account the system features and enables the effective implementation of manufacturing capabilities in modern conditions of production organization and sales in terms of market saturation

C–H Functionalization Reactivity of a Nickel–Imide

This article discusses C-H functionalization reactivity of a Nickel-Imide