Search results for "Cyanide"
showing 10 items of 180 documents
A Simple Complex on the Verge of Breakdown: Isolation of the Elusive Cyanoformate Ion
2014
Cyanide Hitches a Ride Cyanide is a by-product of the biosynthesis of ethylene in plants and it has been somewhat puzzling how the ion is safely removed before it can shut down enzymatic pathways by coordination to catalytic iron centers. A proposed mechanism has implicated the cyanoformate ion—essentially, a weak adduct of cyanide and carbon dioxide—as the initial product, although its lifetime was uncertain. Murphy et al. (p. 75 ; see the Perspective by Alabugin and Mohamed ) crystallized this previously elusive adduct and found that its solution-phase stability varies inversely with the dielectric properties of the medium. The results bolster a picture in which the adduct shuttles the cy…
Crystal structure of a low-spin poly[di-μ3-cyanido-di-μ2-cyanido-bis(μ2-2-ethylpyrazine)dicopper(I)iron(II)]
2019
In the title metal–organic framework, [Fe(C6H8N2)2{Cu(CN)2}2] n , the low-spin FeII ion lies at an inversion centre and displays an elongated octahedral [FeN6] coordination environment. The axial positions are occupied by two symmetry-related bridging 2-ethylpyrazine ligands, while the equatorial positions are occupied by four N atoms of two pairs of symmetry-related cyanide groups. The CuI centre is coordinated by three cyanide carbon atoms and one N atom of a bridging 2-ethylpyrazine molecule, which form a tetrahedral coordination environment. Two neighbouring Cu atoms have a short Cu...Cu contact [2.4662 (7) Å] and their coordination tetrahedra are connected through a common edge between…
Crystal structure of catena-poly[[[(2-ethoxypyrazine-κN)copper(I)]-di-μ2-cyanido] [copper(I)-μ2-cyanido]]
2019
The title compound, {[Cu(EtOpz)(CN)2][CuCN]}n, where EtOpz is 2-ethoxypyrazine, is a two-dimensional polymeric copper complex with different coordination environments of the two CuI ions. One Cu atom is coordinated to the 2-ethoxypyrazine molecule and two bridging cyanide ligands, equally disordered over two sites. The second Cu atom is coordinated by two disordered over two sites bridging cyanide groups. Two copper–cyanide chains are connected through Cu⋯Cu contact.
A Germanium Isocyanide Complex Featuring (n → π*) Back-Bonding and Its Conversion to a Hydride/Cyanide Product via C-H Bond Activation under Mild Con…
2012
Reaction of the diarylgermylene Ge(ArMe6)2 [ArMe6 = C6H3-2,6-(C6H2-2,4,6-(CH3)3)2] with tert-butyl isocyanide gave the Lewis adduct species (ArMe6)2GeCNBut, in which the isocyanide ligand displays a decreased C–N stretching frequency consistent with an n → π* back-bonding interaction. Density functional theory confirmed that the HOMO is a Ge–C bonding combination between the lone pair of electrons on the germanium atom and the C–N π* orbital of the isocyanide ligand. The complex undergoes facile C–H bond activation to produce a new diarylgermanium hydride/cyanide species and isobutene via heterolytic cleavage of the N–But bond. peerReviewed
Characterization of a Double Metal Cyanide (DMC)-Type Catalyst in the Polyoxypropylation Process: Effects of Catalyst Concentration
2014
The alkaline catalysts commonly applied to alkoxylation are characterized by a limited spectrum of activity caused by an irreversible termination of the polyether chains. The presented results show that double metal cyanide (DMC) catalysts reduce or eliminate the aforementioned adverse rearrangement of hydroxyl groups. Moreover, DMC catalysts indicate high activity at low concentrations (ppm range), as expressed by high polymerization rates. It was demonstrated that decreased concentrations of DMC catalyst irreversibly influence its reactivity and the dispersity of the obtained products, as exemplified by the production and determination of selected polyoxypropylenediols at different concen…
Following Hydrogen Cyanide in the Valencian Country (1907-1933): Risk, Accidents and Standards in Fumigation
2019
Abstract Pests had represented a major problem in agriculture for centuries, but the huge changes in the food chain around the late nineteenth century intensified their effects in a totally unprecedented way and many new chemical substances were introduced in the attempt to control them. In this paper I will focus on the implementation of hydrogen cyanide, a highly toxic pesticide which has not received particular consideration from researchers to date. I shall analyse the introduction of this pesticide in the Valencian Country and focus on the attention given to the safety of workers and consumers. I aim to examine the role of the poison in its different uses and analyse the impact of each…
Enzymatic Determination in Serum of Lathyritic and Prednisone-treated Lathyritic Rats
1966
WHILE a remarkably raised serum-level of transaminases and aldolase is found in dermatomyositis, such augmentation, as a rule, is not found in cases of severe muscular involvement of scleroderma and disseminated lupus erythematosus (acutus)1–3.
Magneto-structural correlations in discrete $Mn^{II}‐W^V$ cyano‐bridged assemblies with polyimine ligands
2010
We present the magneto-structural correlations for two novel discrete cyano-bridged assemblies based on cationic complexes of manganese(II) with diimine ligands and octacyanotungstate(V) ions. The crystal structure of [Mn II (terpy)(dmf)-(H 2 O) 2 ][Mn II (terpy)(H 2 O)(dmf)(μ-NC)W V (CN) 7 ] 2· 6H 2 O (1) (terpy = 2,2';6',2"-terpyridine, dmf = dimethylformamide) contains dinuclear {Mn II W V } - cyano-bridged anions, while the crystal structure of [Mn II (phen) 3 ] 2 [MnII(phen) 2 (μ-NC) 2 -W V (CN) 6 ] 2 (ClO 4 ) 2 ·9H 2 O (2) (phen = 1,10-phenanthroline) is built of tetranuclear {Mn II 2 W V 2} 2- square anions. Intramolecular Mn-W magnetic interactions through the cyano bridges are repr…
Diversity of Isomerization Patterns and Protolytic Forms in Aminocarbene PdII and PtII Complexes Formed upon Addition of N,N′-Diphenylguanidine to Me…
2017
Reaction of the palladium(II) and platinum(II) isocyanide complexes cis-[MCl2(CNR)2] [M = Pd, R = C6H3(2,6-Me2) (Xyl), 2-Cl-6-MeC6H3, cyclohexyl (Cy), t-Bu, C(Me)2CH2(Me)3 (1,1,3,3-tetramethylbuth-1-yl abbreviated as tmbu); M = Pt, R = Xyl, 2-Cl-6-MeC6H3, Cy, t-Bu, and tmbu] with N,N′-diphenylguanidine (DPG) leads to DPG-derived metal-bound deprotonated acyclic diaminocarbene (ADC) species. This reaction occurs via a two-step process, involving the initial coupling of the guanidine with one of the isocyanides and leading to deprotonated monocarbene monochelated species, while the next addition grants the deprotonated bis-carbene bis-chelated metal compounds. DPG behaves as nucleophile, depr…
Global urban environmental change drives adaptation in white clover
2022
Made available in DSpace on 2022-04-28T19:52:06Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-03-18 Urbanization transforms environments in ways that alter biological evolution. We examined whether urban environmental change drives parallel evolution by sampling 110,019 white clover plants from 6169 populations in 160 cities globally. Plants were assayed for a Mendelian antiherbivore defense that also affects tolerance to abiotic stressors. Urban-rural gradients were associated with the evolution of clines in defense in 47% of cities throughout the world. Variation in the strength of clines was explained by environmental changes in drought stress and vegetation cover that varied am…