Trans Product Research Articles

A DFT mechanistic study on [4 + 3] cycloaddition reactions of oxyallyl cations and five-membered cyclopentadiene derivatives

The mechanism and stereo-selectivity of [4 + 3] cycloaddition reaction involving oxyallyl cations and five-membered cyclodienes (cyclopentadiene, furan and thiophene) for the construction of seven-membered cycloadducts has been studied with DFT at B3LYP/6-311G∗∗ level. The reaction can go through a concerted addition pathway via compact or extended transition states, or through a stepwise pathway. The concerted pathway is slightly favored kinetically (by 4 kcal/mol), via the compact transition state for furan and thiophene and the extended transition state for cylopentadiene, leading to a cis-endo product (W-configuration). Even though the stepwise addition pathway is not completely ruled out, it is not selective as the formation of the trans and cis-endo products through stepwise addition are very close in energy. Generally, the cycloadduct with the U configuration is more stable than the W and sickle configurations, and thus the kinetically-favored W conformer is expected to flip into the themodynamically-favored U conformer.

Bimetallic Substituted Ceria: An Alternative Approach to Ligand-Free Heck-Mizoroki Cross-Coupling Reactions

This work describes Ce0.89Zr0.03Pd0.08O2-δ as a heterogeneous catalyst for Heck-Mizoroki reactions. The material was synthesised by urea-assisted solution combustion to give a zirconium-stabilised cerium fluorite structure, with a fraction of palladium incorporated into the host structure. Characterisation techniques included ICP-OES, P-XRD and electron microscopy. The catalyst illustrated a high TOF of 1860 h−1 for the cross-coupling of iodobenzene with methyl acrylate, when trimethylamine (TEA) was used as a base and dimethylformamide (DMF) as the solvent at 130 °C. To establish the activity of coupling pairs, screening was limited to aryliodobenzenes, with various electronic properties, to determine the influence of aryliodobenzene electronic density on the trans product yield. Electron-donating substituents showed good yields, while electron-withdrawing groups had lower yields. Furthermore, various classes of electron-deficient olefins were screened to determine any effect on the trans product yield. Electron-deficient olefins showed higher yields with regard to the trans product than neutral styrene.

A single amino acid substitution in the FAD-binding domain causes the inactivation of Propionibacterium Acnes isomerase.

We previously demonstrated the efficient production of trans 10, cis 12-conjugated linoleic acid (t10c12-CLA) in Lactococcus lactis by ectopically expressing a Propionibacterium acnes isomerase (pai) gene and also mentioned that a recombinant strain was unable to accumulate t10c12-CLA product, despite the normal transcription. Here, the molecular analysis indicated that this mutated strain harbors a pai gene with a single-nucleotide mutation converting GC50A to GTA, leading to a corresponding change of Alanine residue into Valine. The expression of the reverse mutation resulted in the recovery for enzyme activity. Site-directed mutagenesis indicated that the codon usage of Val17 was not responsible for the enzyme inactivation in the Ala17Val mutation. Western blot analysis revealed that the recombinant PAI protein was not detectable in the His tag-marked Ala17Val mutant. It is, therefore, reasonable to assume that Ala17 residue is critical for PAI functionality.Abbreviations: pai: propionibacterium acnes isomerase; CLA: conjugated linoleic acid; t10c12-CLA: trans 10, cis 12-CLA; LA: linoleic acid (18:2n-6); FAD: flavin adenine dinucleotide.

Synthetic Strategies for Trapping the Elusive trans-Dirhodium(II,II) Formamidinate Isomer: Effects of Cis versus Trans Geometry on the Photophysical Properties.

The cis- and trans-dirhodium(II,II) complexes cis-[Rh2(μ-DTolF)2(μ-np)(MeCN)4][BF4]2 (1; DTolF = N,N'-di-p-tolylformamidinate and np = 1,8-naphthyridine), cis- and trans-[Rh2(μ-DTolF)2(μ-qxnp)(MeCN)3][BF4]2 [2 and 3, respectively, where qxnp = 2-(1,8-naphthyridin-2-yl)quinoxaline], and trans-[Rh2(μ-DTolF)2(μ-qxnp)2][BF4]2 (4) were synthesized and characterized. A new synthetic methodology was developed that consists of the sequential addition of π-accepting axially blocking ligands to favor formation of the first example of a bis-substituted formamidinate-bearing trans product. Isolation of the intermediates 2 and 3 provides insight into the mechanistic requirements for obtaining 4 and the cis analogue, cis-[Rh2(μ-DTolF)2(μ-qxnp)2][BF4]2 (5). Density functional theory calculations provide support for the synthetic mechanism and proposed intermediates. The metal/ligand-to-ligand charge-transfer (ML-LCT) absorption maximum of the trans complex 4 at 832 nm is red-shifted by 1173 cm-1 and exhibits shorter lifetimes of the 1ML-LCT and 3ML-LCT excited states, 3 ps and 0.40 ns, respectively, compared to those of the cis analogue 5. The shorter excited-state lifetimes of 4 are attributed to the longer Rh-Rh bond of 2.4942(8) Å relative to that in 5, 2.4498(2) Å. A longer metal-metal bond reflects a decreased overlap of the Rh atoms, which leads to more accessible metal-centered excited states for radiationless deactivation. The 3ML-LCT excited states of 4 and 5 undergo reversible bimolecular charge transfer with the electron donor p-phenylenediamine when irradiated with low-energy light. These results indicate that trans isomers are a source of unexplored tunability for potential p-type semiconductor applications and, given their distinct geometric arrangement, constitute useful building blocks for supramolecular architectures with potentially interesting photophysical properties.

Antioxidant and anti-isomerization effects of sesamol and resveratrol on high oleic acid peanut oil

In the present study, the protective effects of sesamol and resveratrol on high oleic acid peanut oil were investigated. Different amounts of sesamol, resveratrol, and their combinations were added to the high oleic acid peanut oil to investigate the antioxidant effect and anti-isomerization effect to prevent cis to trans isomerization of double bonds. Rancimat results showed that the oil had the longest oxidation inducing time after adding 0.08% sesamol or 0.06% resveratrol (v/v). Thermogravimetric analysis suggested that when sesamol and resveratrol were added at 0.08% and 0.04% (v/v), the oxidation decomposition temperature was the highest. Schaal oven experiments indicated that the addition of sesamol and resveratrol could significantly reduce the peroxide content of high oleic acid peanut oil. The total fatty acid content in the oil samples increased significantly after high temperature treatment at 180 °C or 240 °C, and three new thermal isomerization trans products were measured (C18:1-9t, C18:2-9c,12t, C18:2-9t,12c). Meanwhile, the addition of sesamol (0.08%, v/v) or resveratrol (0.06%, v/v) significantly reduced the content of unsaturated fatty acid. For high oleic acid peanut oil heated to 180 °C, sesamol and resveratrol showed a better inhibitory effect on the production of trans-oleic acid than when heating at 240 °C.

Abstracting Otherwise: In Search for a Common Strategy of Arts and Computing

Abstracting Otherwise: In Search for a Common Strategy of Arts and Computing Goda Klumbytė (bio) and Loren Britton (bio) “Abstraction” in digital culture and in the arts is a contested term. As a technical concept in computing, it refers to the process of managing complexity through modeling and selective hiding or condensing of information and plays a key role in the development of software and computing architectures. In the arts, particularly in the West, abstraction is intertwined with histories of image-making, from the medium of photography to the movement of Impressionism and beyond, and it is often posited within a (false) binary of abstraction vs. representation. In the Western arts canon, abstraction after the invention of photography also tends to exclude certain artists that are marked as not artists, such as self-taught artists, women artists, craft artists, disabled artists, POC artists, and other others.1 In the digital culture, abstraction invokes the move away from matter and corporeality. Characteristic of the Western rationality, while also knitted into the understanding of the digital itself, it thus can be said to similarly reproduce the exclusion of those who are seen as too corporeal, too particular.2 Our own thinking on abstraction is the result of a slow burn of working through translations and attempting to find a common language between our different disciplines. Translations between us necessarily take place in and between our modes of praxis, namely, critical-theory-informed analysis of computing and collaborative interdisciplinary art-making. In our work together, we began [End Page 19] experimenting with thinking from our fields about the potential of abstraction as a strategy for composing a plane of relations and intensities—of doing abstraction differently. In this experimental, thoughts-in-progress text, we reflect on different discourses that we inhabit and attempt to propose some intersections where a common vocabulary could be formed. Click for larger view View full resolution Figure 1. Loren Britton, Mouth Translations (2019). Marker on paper (23.4 × 16.5 in.). Courtesy of the Artist, Share Alike. Relying on trans*feminist, critical computing, new materialist perspectives as well as relational ontologies, we approach abstraction between arts and computing and investigate its potential through a theoretical lens stemming from the aforementioned bodies of thought as well as our own practices. By situating abstraction in the histories of Western science and philosophy, as well as the history of Western painting, we are exploring how this term can be reconfigured and rethought in a way that would leave space for the imaginary and for the configuration of unexpected elements, while maintaining responsibility in its construction and refraining from erasure, straightforward extraction, or disappearing peoples. [End Page 20] Our work engages intersemiotic translation as a metaphor for how to think between disciplines, understood as the act of translating one language to another while keeping in mind the political and culturally embedded process that can impact both the originating and receiving cultures.3 Intersemiotic translation often carries a source text or artifact across the sign systems and creates a likeness between different cultures. This approach recognizes that there are multiple possible versions of source and target texts and can help inform why there may be preconceptions or biases embedded in any translational work. This is a kind of translation that attempts to remain accountable to its source and destination by giving a network of reference points spoken, physical, and cited to form the way that thinking is constructed. Our starting point for experimenting with assembling a common ground begins with the question: What are the connections between concepts that operate in different disciplines—such as “abstraction” in computing and in the arts? How does abstraction (computational/artistic) relate to matter and matter-reality? What kind of implications does this have for arts, and what kind of political potential can it open up? In investigating these questions, we suggest to rethink abstraction as a process of production and manipulation of trans*re*lationalities. Taking theoretical thought as a meeting venue for our collaborative questioning, we introduce trans*re*lationality as a new concept that entails coagulation of the terms transing, translating, and relating, and discuss its theoretical inheritances. Finally, we propose that rethinking...

Annulation of Oxime-Ether Tethered Donor-Acceptor Cyclopropanes.

Novel oxime-ether tethered cyclopropanes, when exposed to Yb(OTf)3 and heat, annulate to generate hydropyrrolo-oxazines products that can be taken to their respective pyrrolidines via hydrogenative N-O bond cleavage. The hydropyrrolo-oxazines are generated in a diastereoselective manner isolating the cis or trans product based on the temperature of the reaction. 20 examples of selective cis and trans hydropyrrolo-oxazines were generated in high yields by temperature control.

Hydroboration of Alkenes and Alkynes Employing Earth‐Abundant Metal Catalysts

AbstractIron complexes [BIAN]Fe(I)(η6‐toluene) (M1) and [BIAN]FeCl2 (M2) (BIAN=bis(2,6‐diisopropylaniline)acenaphthene) were found to be viable catalysts for the regioselective hydroboration of alkynes and alkenes. The hydroboration of alkynes and alkenes in the presence of HBpin and an activator at 70 °C afforded linear vinyl and alkyl boronic esters, respectively. Selectivity up to 98% was observed for alkyl boronic esters and exclusive formation of trans product was observed for vinyl boronic esters.

1,3-Chlorine Shift to a Vinyl Cation: A Combined Experimental and Theoretical Investigation of the E-Selective Gold(I)-Catalyzed Dimerization of Chloroacetylenes.

Metal-catalyzed dimerization reactions of terminal acetylenes are well known in the literature. However, only a few examples of the dimerization of halogen-substituted acetylenes are described. The products of the latter metal-catalyzed dimerization are the branched head-to-tail enynes. The formation of the corresponding linear head-to-head enynes has not been reported yet. Herein, we demonstrate by means of quantum chemical methods and experiments that the head-to-head dimerization of chloroarylacetylenes can be achieved via mono gold catalysis. Under the optimized conditions, a clean and complete conversion of the starting materials is observed and the dimeric products are obtained up to 75% NMR yield. A mechanistic investigation of the dimerization reaction reveals that the branched head-to-tail vinyl cation is energetically more stable than the corresponding linear head-to-head cation. However, the latter can rearrange by an unusual 1,3-chlorine shift, resulting in the highly stereoselective formation of the trans product, which corresponds to the gold complex of the head-to-head E-enyne. The activation barrier for this rearrangement is extremely low (ca. 2 kcal/mol). As the mono gold-catalyzed dimerization can be conducted in a preparative scale, this simple synthesis of trans-1,2-dichloroenynes makes the gold(I)-catalyzed head-to-head dimerization of chloroarylacetylenes an attractive method en route to more complex conjugated enyne systems and their congeners.

Demystifying trans*+ voice education: The Transgender Singing Voice Conference

Trans*+ is an inclusive, expansive, and fluid term that refers to a population that encompasses people who are transgender, third gender, non-gender, two-spirit or any other identity that is not cisgender. Trans*+ topics are often considered taboo or exotic, which manifests in society as an enforced ignorance that creates a shroud of mystery around the trans*+ community. While music educators’ attitudes toward working with trans*+ students are generally positive, many educators are not sure how to teach trans*+ singers. This case study on the Transgender Singing Voice Conference 2017, an academic and pedagogical gathering, explores the issues of importance identified by conference attendees and how the conference format addressed those issues. Data analysis identified important themes of interest related to the vocal production, pedagogy, physiology, and identity of trans*+ singers. An overwhelming majority (95%) of participants stated they acquired new knowledge at the conference. Representation and intersectionality were topics not adequately addressed according to the attendees. Findings indicate that trans*+ attendees and allies were empowered due to the demystification of trans*+ experiences. The conference provided a space for trans*+ singers to learn about their voices and for their allies to gather resources.

Selective Photocatalytic C-F Borylation of Polyfluoroarenes by Rh/Ni Dual Catalysis Providing Valuable Fluorinated Arylboronate Esters.

A highly selective and general photocatalytic C-F borylation protocol that employs a rhodium biphenyl complex as a triplet sensitizer and the nickel catalyst [Ni(IMes)2] (IMes = 1,3-dimesitylimidazoline-2-ylidene) for the C-F bond activation and defluoroborylation process is reported. This tandem catalyst system operates with visible (blue, 400 nm) light and achieves borylation of a wide range of fluoroarenes with B2pin2 at room temperature in excellent yields and with high selectivity. Direct irradiation of the intermediary C-F bond oxidative addition product trans-[NiF(ArF)(IMes)2] leads to very fast decomposition when B2pin2 is present. This destructive pathway can be bypassed by indirect excitation of the triplet states of the nickel(II) complex via the photoexcited rhodium biphenyl complex. Mechanistic studies suggest that the exceptionally long-lived triplet excited state of the Rh biphenyl complex used as the photosensitizer allows for efficient triplet energy transfer to trans-[NiF(ArF)(IMes)2], which leads to dissociation of one of the NHC ligands. This contrasts with the majority of current photocatalytic transformations, which employ transition metals as excited state single electron transfer agents. We have previously reported that C(arene)-F bond activation with [Ni(IMes)2] is facile at room temperature, but that the transmetalation step with B2pin2 is associated with a high energy barrier. Thus, this triplet energy transfer ultimately leads to a greatly enhanced rate constant for the transmetalation step and thus for the whole borylation process. While addition of a fluoride source such as CsF enhances the yield, it is not absolutely required. We attribute this yield-enhancing effect to (i) formation of an anionic adduct of B2pin2, i.e., FB2pin2-, as an efficient, much more nucleophilic {Bpin-} transfer reagent for the borylation/transmetalation process, and/or (ii) trapping of the Lewis acidic side product FBpin by formation of [F2Bpin]- to avoid the formation of a significant amount of NHC-FBpin and consequently decomposition of {Ni(NHC)2} species in the reaction mixture.

Iron(III)-catalyzed selective direct olefination of dihydropyrimidinone with aromatic aldehyde

Herein, we describe a practical approach for direct vinylogous aldol condensation of Biginelli product for carbon–carbon double bond formation at methyl group of 6-methyl dihydropirimidinone by using hydrated ferric chloride. With aromatic aldehydes, the method yields stereoselectively trans products. The olefination reaction is applicable with aldehyde without chelating (with Fe III) functional group. DHPMs with carboxylate ester and arylidene at C-6 methyl are not known. The method opens up a new avenue for the synthesis of a wide variety of DHPMs. The olefin products were subjected to dihydroxylation reaction. SYNOPSIS A convenient and facile C6-olefination at methyl centre of dihydropyrimidinones (DHPMs) has been observed in acetonitrile in the presence of hydrated $$\hbox {FeCl}_{3}$$ . The method is simple, inexpensive, and stereoselectively trans.

Technetium and Rhenium Schiff Base Compounds for Nuclear Medicine: Syntheses of Rhenium Analogues to 99mTc-Furifosmin.

Rhenium, the third-row congener of technetium, is often used to develop the macroscopic chemistry of potential 99mTc diagnostic radiopharmaceuticals. The rhenium analogues to 99mTc-furifosmin are being developed for potential radiotherapy of multidrug-resistant tumors. Complexes of the form trans-[MIII(PR3)2(N2O2-Schiff base)]+ are of interest for the potential imaging and treatment of multidrug-resistant tumors. Reaction of the tetradentate Schiff ligand 4,4'-[(1 E,1' E)-[ethane-1,2-diylbis(azanylylidene)]bis(methanylylidene)]bis(2,2,5,5-tetramethyl-2,5-dihydrofuran-3-ol) (tmf2enH2) with the M(V) starting materials ( nBu4N)[TcOCl4] and ( nBu4N)[ReOCl4] gave the monomeric products trans-[TcOCl(tmf2en)] and trans-[ReOCl(tmf2en)], respectively. Reduction of in situ formed trans-[ReOCl(tmf2en)] by various tertiary phosphines yielded disubstitued Re(III) products of the general type trans-[ReIII(PR3)2(tmf2en)]+. The rhenium(III) compounds were found to be water-soluble and stable in aqueous solution. Reversible ReIII/ReIV and ReIII/ReII redox processes were observed at about 0.8-0.9 and -0.65 to -0.8 V, respectively, for each of the rhenium(III) species. Reaction of in situ formed trans-TcOCl(tmf2en) with triethylphosphine yielded the reduced, disubstituted trans-[Tc(PEt3)2(tmf2en)]PF6. A reversible TcIII/TcII redox couple was observed for the technetium(III) species, about 200 mV less negative than their rhenium(III) analogues, in addition to an irreversible TcIII/TcIV process. All compounds were characterized using conventional spectroscopic techniques, single-crystal X-ray crystallography, and cyclic voltammetry.

Synthesis of Enantiomerically Pure 3-Substituted Piperazine-2-acetic Acid Esters as Intermediates for Library Production.

The piperazine heterocycle is broadly exploited in FDA-approved drugs and biologically active compounds, but its chemical diversity is usually limited to ring nitrogen substitutions, leaving the four carbon atoms underutilized. Using an efficient six-step synthesis, chiral amino acids were transformed into 3-substituted piperazine-2-acetic acid esters as diastereomeric mixtures whose cis and trans products (dr 0.56 → 2.2:1, respectively) could be chromatographically separated. From five amino acids (both antipodes) was obtained a complete matrix of 20 monoprotected chiral 2,3-disubstituted piperazines, each as a single absolute stereoisomer, all but one in multigram quantities. In keeping with our overall purpose of constructing more Csp3-enriched compound libraries for drug discovery, these diverse and versatile piperazines can be functionalized on either nitrogen atom, allowing them to be used as scaffolds for parallel library synthesis and as intermediates for the production of novel piperazine compounds.

A convenient synthesis of (E)-conjugated polyene sulfonyl derivatives with excellent stereospecificity

A highly selective synthesis of conjugated polyene sulfonyl derivatives is described via the elimination of disulfonyl chloride with readily accessible raw material dihaloalkane. The protocol offers a convenient way to form sulfonamides, sulfonates and even sulfones. Furthermore, this method was manipulated under mild condition with simple operation in high yield to afford only trans products.

Unexpected Alkene Isomerization during Iterative Cross-Coupling To Form Hindered, Electron-Deficient Trienes.

An iterative cross-coupling approach to conjugated trienes was explored as part of a planned stereoselective synthesis of bicyclic terpenes. Using a bifunctional bromoboronate building block, sequential Suzuki coupling reactions were employed to provide a conjugated trienone target containing a tetrasubstituted alkene. During the final cross-coupling step, an unexpected alkene isomerization was observed to give less hindered trans products. Examination of different substrates determined that conjugation to a ketone withdrawing group was responsible for isomerization, rather than steric hindrance of the tetrasubstituted alkene.

Synthesis of Enantiomerically Pure 6-Substituted-Piperazine-2-Acetic Acid Esters as Intermediates for Library Production.

The piperazine heterocycle is broadly exploited in FDA-approved drugs and biologically active compounds, but its chemical diversity is usually limited to ring nitrogen substitutions, leaving the four carbon atoms underutilized. Using an efficient four-step synthesis, chiral amino acids were transformed into 6-substituted piperazine-2-acetic acid esters as diastereomeric mixtures whose cis and trans products could be chromatographically separated. From six amino acids (both antipodes), a complete matrix of 24 monoprotected chiral 2,6-disubstituted piperazines was obtained, each as a single absolute stereoisomer in multigram quantities. These diverse and versatile piperazines can be functionalized on either nitrogen atom, allowing them to be used as scaffolds for parallel library synthesis or intermediates for the production of novel piperazine compounds.

Gold‐Catalyzed Highly Regioselective Coupling Reaction between Alkynes and Aldehydes for the Synthesis of Conjugated Enones

AbstractAn efficient AuCl3/AgSbF6‐catalysed enone synthesis from coupling of alkynes and aldehydes has been presented. The present reaction is very effective, simple and mild and has wide range of substrate scope. Both aryl (electron rich and electron deficient) and aliphatic aldehydes and terminal and internal arylalkynes participated smoothly in the reaction and provided exclusively trans product. This simple reaction can be coupled with other gold catalysed transformations which involve enones as substrates for further development.

Synthesis, characterization and antimicrobial studies of cadmium(II) complexes with a tetraazamacrocycle ( $$\hbox {L}_{\mathrm{B}}$$ L B ) and its cyanoethyl N-pendent derivative $$(\hbox {L}_{\mathrm{BX}}$$ ( L BX )

An isomeric ligand, $$\hbox {L}_{\mathrm{B}}$$ of 3,10-C-meso- $$\hbox {Me}_{8}$$ [14]ane on alkylation reaction with excess acrylonitrile resulted in a stereoselective product trans-(3S,5S,10R,12R)-N1,N8-bis(2-cyanoethyl)-C-meso-derivative, $$\hbox {L}_{\mathrm{BX}}$$ . Reaction of $$\hbox {L}_{\mathrm{B}}$$ with Cd( $$\hbox {ClO}_{4})_{2}\cdot 4\hbox {H}_{2}\hbox {O}$$ in methanol gave the octahedral complex, [Cd( $$\hbox {L}_{\mathrm{B}})$$ ( $$\hbox {ClO}_{4})_{2}$$ ] whereas interaction of the ligand $$\hbox {L}_{\mathrm{BX}}$$ with Cd( $$\hbox {NO}_{3})_{2}\cdot 4\hbox {H}_{2}\hbox {O}$$ in methanol yielded a square pyramidal mononitratocadmium(II) nitrate complex, [Cd( $$\hbox {L}_{\mathrm{BX}})$$ ( $$\hbox {NO}_{3})$$ ]( $$\hbox {NO}_{3})$$ and an octahedral dinitratocadmium(II) complex, [Cd( $$\hbox {L}_{\mathrm{BX}})$$ ( $$\hbox {NO}_{3})_{2}$$ ]. The complexes, [Cd( $$\hbox {L}_{\mathrm{B}})$$ ( $$\hbox {ClO}_{4})_{2}$$ ] and [Cd( $$\hbox {L}_{\mathrm{BX}})$$ ( $$\hbox {NO}_{3})_{2}$$ ] underwent axial substitution reactions with KCNS and KBr to produce octahedral diisothiocyanatocadmium(II) complexes, [Cd( $$\hbox {L}_{\mathrm{B}})$$ (NCS) $$_{2}$$ ] and [Cd( $$\hbox {L}_{\mathrm{BX}})$$ (NCS) $$_{2}$$ ] and octahedral dibromidocadmium(II) complexes, [Cd( $$\hbox {L}_{\mathrm{B}})\hbox {(Br)}_{2}$$ ] and [Cd( $$\hbox {L}_{\mathrm{BX}})\hbox {(Br)}_{2}$$ ], respectively; whereas, [Cd( $$\hbox {L}_{\mathrm{BX}})$$ ( $$\hbox {NO}_{3})$$ ]( $$\hbox {NO}_{3})$$ underwent axial addition with KCl, simultaneous axial substitution and anion exchange with KCNS and simultaneous axial addition, substitution and anion exchange with $$\hbox {NaClO}_{4}\cdot 6\hbox {H}_{2}\hbox {O}$$ to produce octahedral [Cd( $$\hbox {L}_{\mathrm{BX}})$$ ( $$\hbox {NO}_{3})$$ Cl], square planar octahedral [Cd( $$\hbox {L}_{\mathrm{BX}})$$ ( $$\hbox {H}_{2}\hbox {O}$$ ) $$_{2}$$ ]( $$\hbox {ClO}_{4})_{2}$$ , respectively. The newly prepared compounds have been characterized by different analytical and spectroscopic methods. The antibacterial activities of the ligands, metal salts and complexes have been tested against two selected gram positive bacteria and two gram negative bacteria.

Ruthenium Carbene Complexes Analogous to Grubbs-I Catalysts Featuring Germylenes as Ancillary Ligands

Reactions of the first-generation Grubbs’ catalyst trans-[RuCl2(CHPh)(PCy3)2] (1) with the amidinatogermylenes Ge(tBu2bzam)R (R = tBu (L1), CH2SiMe3 (L2); tBu2bzam = N,N′-bis(tertbutyl)benzamidinate) have allowed the isolation and full characterization of the first specimens of Grubbs-type carbene complexes featuring heavier tetrylenes as ancillary ligands, namely, the disubstituted derivatives trans-[RuCl2(CHPh)(L1)2] (3) and cis-[RuCl2(CHPh)(L2)2] (7), which curiously differ in the arrangement of their germylene ligands. DFT calculations have revealed that the different volumes of L1 and L2 (the former is larger than the latter) are responsible for the different stereochemistry of 3 and 7. NMR-monitoring of the reaction solutions has allowed the observation of the monosubstituted intermediates trans-[RuCl2(CHPh)(L)(PCy3)] (L = L1 (2), L2 (5)) and their evolution to either the disubstituted final product (for L1) trans-[RuCl2(CHPh)(L1)2] (3) or the short-lived disubstituted intermediate (for L2) trans-[RuCl2(CHPh)(L2)2] (6). Complex 7 arises from a trans-to-cis isomerization of intermediate 6. As olefin metathesis catalysts, both 3 and 7 promoted the ring-closing metathesis of diethyl 2,2-diallylmalonate and the ring-opening metathesis polymerization of norbornene, but their catalytic activity decreased with the reaction time, indicating catalyst decomposition.