Crystalline Complex
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Author(s):  
Ilia Garkul ◽  
Andrey Zadesenets ◽  
Evgeny Filatov ◽  
Iraida Baidina ◽  
Sergey Tkachev ◽  
...  

New coordination compounds trans-bis(oxalato)diaquarhodiate sodium dihydrate Na[Rh(H2O)2Ox2]·2H2O (crystallizes in two polymorphic forms NaRh-1 and NaRh-2), trans-bis(oxalato)hydroxoaquarhodiate sodium tetrahydrate Na2[Rh(H2O)(OH)Ox2]·4H2O (Na2Rh) and trans-bis(oxalato)diaquarhodic acid tetrahydrate (H3O)[Rh(H2O)2Ox2]·4H2O (HRh) are synthesized. The compounds are characterized by IR spectroscopy, elemental analysis and single crystal X-ray diffraction. NaRh-1, NaRh-2 and Na2Rh crystallize in space group P 1. Trans-bis(oxalato)diaquarhodic acid exists not only in solution, but can also crystallize as a tetrahydrate (space group C2/c). The formation of various species in solution of rhodium hydroxide in oxalic acid and their redistribution were studied using 103Rh NMR spectroscopy.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jacek Malinowski ◽  
Dagmara Jacewicz ◽  
Artur Sikorski ◽  
Mariusz Urbaniak ◽  
Przemysław Rybiński ◽  
...  

AbstractThe contemporary search for new catalysts for olefin oligomerization and polymerization is based on the study of coordinating compounds and/or organometallic compounds as post-metallocene catalysts. However known catalysts are suffered by many flaws, among others unsatisfactory activity, requirement of high pressure or instability at high temperatures. In this paper, we present a new catalyst i.e. the crystalline complex compound possesing high catalytic activity in the oligomerization of olefins, such as 2-chloro-2-propen-1-ol and ethylene under very mild conditions (room temperature, 0.12 bar for ethylene oligomerization, atmospheric pressure for 2-chloro-2-propen-1-ol oligomerization). New material—Cat-CrNP ([nitrilotriacetato-1,10-phenanthroline]chromium(III) tetrahydrate) has been obtained as crystalline form of the nitrilotriacetate complex compound of chromium(III) with 1,10-phenanthroline and characterized in terms of its crystal structure by the XRD method and by multi-analytical investigations towards its physicochemical propeties The yield of catalytic oligomerization over Cat-CrNP reached to 213.92 g · mmol−1 · h−1· bar−1 and 3232 g · mmol−1 · h−1 · bar−1 for the 2-chloro-2-propen-1-ol and ethylene, respectively. Furthemore, the synthesis of Cat-CrNP is cheap, easy to perform and solvents used during preparation are environmentally friendly.


Author(s):  
V. P. Baryshok ◽  
E. A. Zel'bst

To examine the effect of 5s2 lone electron pair of antimony atom on the reaction of antimony trifluoride and triethanolamine in the presence of sodium methylate, the crystal structure of the reaction product -2-fluoro-6-(2-hydroxyethyl)-1,3-dioxa-6-aza-2-stibacy-cylooctane (1-fluoro-2-hydrostibatrane) FSb (OCH2CH2)2NCH2CH2OH) was confirmed. In the compound structure, the hydrogen atom of the 2-hydtoxyethyl group of each molecule forms an intermolecular hydrogen bond with the oxygen atom of one of the five-membered SbOCH2CH2N half-cycles in a neighbouring molecule. A geometry of both five-member N-C-C-O-Sb heterocycles, end-capped by transannular N→Sb bond in the 1-fluoro-2-hydrostibatrane molecule, is almost identical. C-O, C-C, N-C interatomic distances and valence angles in two endocyclic units (NCCOSb) are comparable to those observed in RSi(OCH2CH2)3N silatranes. A coordination polyhedron of the Sb atom can be represented as a transition from a bisphenoid to Sb(O3)N trigonal pyramid, with a nitrogen atom at the apex and three oxygen atoms in the base. The N→Sb transannular coordinate bond length is 2.402(4) Å, which is 0.40 Å greater than the Sb-N covalent bond standard length. The Sb-F bond (1.997(4) Å) is 0.12 Å longer than that in the SbF3 molecule, and insignificantly shorter than that of the Sb-Fax (2.028(3) Å) in the SbF3Gly crystalline complex. The fluorine atom substantially strays from the N→Sb axis to the direction of O(1) and O(2) atoms. The oxygen atom of the 2-hydroxyethyl group lies at a distance of 2.899(3) A from that of Sb, intermediate between the valence bond length and the sum of the Van der Waals radii of these atoms. Combined with the F atom position, one can assume the 1-fluoro-2-hydrostibatrane crystal structure as a “frozen” state of the SNi(Sb) type nucleophilic attack of the oxygen atom, uncompleted because of its repulsion by the 5s2 lone electronic pair of antimony atom.


Symmetry ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 696
Author(s):  
M. T. Cardoso ◽  
B. Feijóo ◽  
A. P. G. Castro ◽  
F. J. Ribeiro ◽  
P. R. Fernandes

Cataract is a disease opacifying the crystalline, leading to a blurred vision and ultimately to blindness. With an aging population, the incidence of cataract is increasing, as well as the number of treatments. The solution available is its complete removal, followed by an implant of an intraocular lens (IOL). Although the post-operative complications on cataract surgeries have been decreasing in general, the bag-IOL complex dislocation is still an issue, probably being the most serious complication under this procedure. In this work, an axisymmetric Finite Element (FE) modelling strategy of the crystalline complex during the process of accommodation under cataract surgery is proposed. The goal was to understand the influence of biomechanical alterations promoted by the IOL on bag-IOL dislocation after surgery. An increase of force and stress in the zonules was verified in the pseudophakic eye compared to the complete eye, which could explain why zonules break years after surgery, leading to the bag-IOL dislocation. The axisymmetric FE model proposed in this work is innovative in this field, which still lacks detailed research, and can be an important complement for the clinical and biomechanical work on the crystalline complex.


2021 ◽  
Author(s):  
Konstantinos Soukis ◽  
Daniel Stockli

<p>The birth and death of oceanic areas have often proved to involve contemporaneous destruction of previously created and evolved oceanic domains and the initiation of new ones in back-arc areas. As a result, several and often competing geodynamic processes, have been taking place at the same time, thus creating a complex tectonostratigraphy.</p><p>The Attic-Cycladic Crystalline Complex (ACCC), in the Aegean Sea (Greece), the outcome of the formation and destruction of Paleotethyan and Tethyan oceanic domains, is one such case. Four major units have been identified in the ACCC. These are from top to bottom, the complex Upper Cycladic Nappe, the Cycladic Blueschist Unit, the pre-alpine Cycladic Basement, and the Basal Unit. The present-day configuration has resulted from an Eocene stage of subduction and metamorphism under blueschist to eclogite facies and an Oligocene-Miocene exhumation and metamorphic core complex formation, through a combination of contractional and extensional mechanisms. Original relations between these four units have been obscured from the Cenozoic tectonometamorphic processes and several conflicting views have been expressed in the literature, regarding the nature of the Cycladic Blueschist domain, the relation between the Cycladic Blueschist Unit and the Cycladic Basement.</p><p>In this paper, we make a reconstruction of the domain, from which the Cycladic Blueschist Unit originated, based on a synthesis of structural, tectonostratigraphic, geochemical, and geochronological data. Through this reconstruction, we attempt to reconcile existing controversies and differences of views in the literature and to highlight the major structures that controlled the main features and geological evolution of this remarkable area.</p>


2021 ◽  
Vol 29 (1) ◽  
pp. 6-15 ◽  
Author(s):  
Zdeněk Dolníček ◽  
Jana Ulmanová

An interesting ore mineralization containing Pb-Bi minerals, present in a thin layer parallel with schistosity of the host amphibolite, was newly recognized in the Libodřice quarry near Kolín (Kutná Hora Crystalline Complex, Czech Republic). The disseminations of ore minerals are formed especially by pyrrhotite and chalcopyrite, less pyrite and accessory galena, native bismuth, cosalite, bismuthinite and joséite-B. The equilibrium textural relationships of rock-forming silicates and main sulphides indicate that the ore assemblage underwent metamorphic recrystallization together with the host rock, however, indications of younger local re-equilibrations under changed physico-chemical conditions (especially temperature, fugacity of sulphur, fugacity of oxygen) were also observed. The presence of polysynthetic lamellae in chalcopyrite suggests for its origin/re-crystallization at temperatures above 550 °C. Sporadic cosalite, stable at temperatures below 425 °C, was probably precursor of pseudomorphs today formed by galena and native bismuth. Pseudomorphs originated at temperatures below 271 °C probably due to local decrease of sulphur fugacity caused by growth of associated pyrrhotite. The local sulphurisation of small amount of native bismuth to bismuthinite and small part of pyrrhotite to pyrite finished the process of ore evolution. The presence of elevated contents of Te, Se and Ni in the studied mineralization confirms the source of these elements in the host rock environment, which was presupposed on the basis of earlier mineralogical study of Alpine-type veins in the area of the Kutná Hora Crystalline Complex.


2020 ◽  
pp. 1-8
Author(s):  
Ferdinando Bosi ◽  
Alessandra Altieri ◽  
Fernando Cámara ◽  
Marco E. Ciriotti

Abstract A green tourmaline sample from the Tzarevskoye uranium–vanadium deposit, close to the Srednyaya Padma deposit, Lake Onega, Karelia Republic, Russia, has been found to be the second world-occurrence of Cr-rich vanadio-oxy-dravite in addition to the Pereval marble quarry, Sludyanka crystalline complex, Lake Baikal, Russia, type-locality. From the crystal-structure refinement and chemical analysis, the following empirical formula is proposed: X(Na0.96K0.02□0.02)Σ1.00Y(V1.34Al0.68Mg0.93Cu2+0.02Zn0.01Ti0.01)Σ3.00Z(Al3.19Cr1.36V0.03Mg1.42)Σ6.00(TSi6O18)(BBO3)3V(OH)3W[O0.60(OH)0.23F0.17]Σ1.00. Together with the data from the literature, a compositional overview of Al–V–Cr–Fe3+-tourmalines is provided by using [6]Al–V–Cr–Fe3+ diagrams for tourmaline classification. These diagrams further simplify the tourmaline nomenclature as they merge the chemical information over the octahedrally-coordinated sites (Y and Z) by removing the issues of uncertainty associated with cation order–disorder across Y and Z. Results show the direct identification of tourmalines by using the chemical data alone.


2020 ◽  
Vol 61 (8) ◽  
Author(s):  
Lukáš Ackerman ◽  
Jana Kotková ◽  
Renata Čopjaková ◽  
Jiří Sláma ◽  
Jakub Trubač ◽  
...  

Abstract The Lu–Hf isotope system and Sr–Nd–Hf–Os isotope systematics of mantle rocks are capable of unravelling the early processes in collision belts, especially in a hot subduction context where the Sm–Nd and U–Pb systems in crustal rocks are prone to resetting owing to high temperatures and interaction with melts during exhumation. To improve models of the Devonian–Carboniferous evolution of the Bohemian Massif, we investigated in detail mafic and ultramafic rocks (eclogite, pyroxenite, and peridotite) from the ultrahigh-pressure and ultrahigh-temperature Kutná Hora Crystalline Complex (KHCC: Úhrov, Bečváry, Doubrava, and Spačice localities). Petrography, multiphase solid inclusions, major and trace element compositions of rocks and minerals, and radiogenic isotopic data document contrasting sources and protoliths as well as effects of subduction-related processes for these rocks. The Úhrov peridotite has a depleted composition corresponding to the suboceanic asthenospheric mantle, whereas Bečváry and Doubrava peridotites represent lithospheric mantle that underwent melt refertilization by basaltic and SiO2-undersaturated melts, respectively. Multiphase solid inclusions enclosed in garnet from Úhrov and Bečváry peridotites represent trapped H2O ± CO2-bearing metasomatizing agents and Fe–Ti-rich melts. The KHCC eclogites either formed by high-pressure crystal accumulation from mantle-derived basaltic melts (Úhrov) or represent a fragment of mid-ocean ridge basalt-like gabbroic cumulate (Spačice) and crustal-derived material (Doubrava) both metamorphosed at high P–T conditions. The Lu–Hf age of 395 ± 23 Ma obtained for the Úhrov peridotite reflects garnet growth related to burial of the asthenospheric mantle during subduction of the oceanic slab. By contrast, Spačice and Doubrava eclogites yield younger Lu–Hf ages of ∼350 and 330 Ma, respectively, representing mixed ages as demonstrated by the strong granulite-facies overprint and trace element zoning in garnet grains. We propose a refined model for the Early Variscan evolution of the Bohemian Massif starting with the subduction of the oceanic crust (Saxothuringian ocean) and associated oceanic asthenospheric mantle (Úhrov) beneath the Teplá–Barrandian at ≥380 Ma, which was responsible for melt refertilization of the associated mantle wedge (Bečváry, Doubrava). This was followed by continental subduction (∼370–360 Ma?) accompanied by the oceanic slab break-off and incorporation of the upwelling asthenospheric mantle into the Moldanubian lithospheric mantle and subsequent coeval exhumation of mantle and crustal rocks at ∼350–330 Ma.


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