302-04-5Relevant articles and documents
Photoredox chemistry in the synthesis of 2-aminoazoles implicated in prebiotic nucleic acid synthesis
Liu, Ziwei,Wu, Long-Fei,Bond, Andrew D.,Sutherland, John D.
supporting information, p. 13563 - 13566 (2020/11/17)
Prebiotically plausible ferrocyanide-ferricyanide photoredox cycling oxidatively converts thiourea to cyanamide, whilst HCN is reductively homologated to intermediates which either react directly with the cyanamide giving 2-aminoazoles, or have the potential to do so upon loss of HCN from the system. Thiourea itself is produced by heating ammonium thiocyanate, a product of the reaction of HCN and hydrogen sulfide under UV irradiation. This journal is
Water-Soluble α-Amino Acid Complexes of Molybdenum as Potential Antidotes for Cyanide Poisoning: Synthesis and Catalytic Studies of Threonine, Methionine, Serine, and Leucine Complexes
Gretarsdottir, Johanna M.,Hambley, Trevor W.,Jonsdottir, Sigridur,Lewis, William,Suman, Sigridur G.
, p. 18190 - 18204 (2020/12/22)
Water-soluble complexes are desirable for the aqueous detoxification of cyanide. Molybdenum complexes with α-amino acid and disulfide ligands with the formula K[(L)Mo2O2(μ-S)2(S2)] (L = leu (1), met (2), thr (3), and ser (4)) were synthesized in a reaction of [(DMF)3MoO(μ-S)2(S2)] with deprotonated α-amino acids; leu, met, thr, and ser are the carboxylate anions of l-leucine, l-methionine, l-threonine, and l-serine, respectively. Potassium salts of α-amino acids (leu (1a), met (2a), thr (3a), and ser (4a)) were prepared as precursors for complexes 1-4, respectively, by employing a nonaqueous synthesis route. The ligand exchange reaction of [Mo2O2(μ-S)2(DMF)6](I)2 with deprotonated α-amino acids afforded bis-α-amino acid complexes, [(L)2Mo2O2(μ-S)2] (6-8). A tris-α-amino acid complex, [(leu)2Mo2O2(μ-S)2(μ-leu + H)] (5; leu + H is the carboxylate anion of l-leucine with the amine protonated), formed in the reaction with leucine. 5 crystallized from methanol with a third weakly bonded leucine as a bridging bidentate carboxylate. An adduct of 8 with SCN - coordinated, 9, crystallized and was structurally characterized. Complexes 1-4 are air stable and highly water-soluble chiral molecules. Cytotoxicity studies in the A549 cell line gave IC50 values that range from 80 to 400 μM. Cyclic voltammetry traces of 1-8 show solvent-dependent irreversible electrochemical behavior. Complexes 1-4 demonstrated the ability to catalyze the reaction of thiosulfate and cyanide in vitro to exhaustively transform cyanide to thiocyanate in less than 1 h.
Thiophosphate - A Versatile Prebiotic Reagent?
Ritson, Dougal J.,Xu, Jiangfeng,Sutherland, John D.
, p. 64 - 67 (2016/12/27)
Described are our preliminary studies on the reactivity of thiophosphate in a setting which correlates with the cyanosulfidic systems chemistry we have previously reported. Thiophosphate adds to various nitrile groups giving the corresponding thioamides in a highly efficient manner and the mechanistic implications are briefly discussed. Thiophosphate can also act as a phosphorylating agent, which was demonstrated with adenosine. The prebiotic availability of thiophosphate must be questioned, but if a plausible synthesis can be found, the advantages it would bring to the field of prebiotic chemistry appear to be highly beneficial.
Synthesis and Structure of Nitride-Bridged Uranium(III) Complexes
Chatelain, Lucile,Scopelliti, Rosario,Mazzanti, Marinella
supporting information, p. 1784 - 1787 (2016/03/01)
The reduction of the nitride-bridged diuranium(IV) complex Cs[{U(OSi(OtBu)3)3}2(-N)] affords the first example of a uranium nitride complex containing uranium in the +III oxidation state. Two nitride-bridged complexes containing the heterometallic fragments Cs2[UIII?-N?-UIV] and Cs3[UIII?-N?-UIII] have been crystallographically characterized. The presence of two or three Cs+ cations binding the nitride group is key for the isolation of these complexes. In spite of the fact that the nitride group is multiply bound to two uranium and two or three Cs+ cations, these complexes transfer the nitride group to CS2 to afford SCN- and uranium(IV) disulfide.
Mechanism of decomposition of the human defense factor hypothiocyanite near physiological pH
Kalmar, Jozsef,Woldegiorgis, Kelemu L.,Biri, Bernadett,Ashby, Michael T.
, p. 19911 - 19921 (2012/01/31)
Relatively little is known about the reaction chemistry of the human defense factor hypothiocyanite (OSCN-) and its conjugate acid hypothiocyanous acid (HOSCN), in part because of their instability in aqueous solutions. Herein we report that HOSCN/OSCN- can engage in a cascade of pH- and concentration-dependent comproportionation, disproportionation, and hydrolysis reactions that control its stability in water. On the basis of reaction kinetic, spectroscopic, and chromatographic methods, a detailed mechanism is proposed for the decomposition of HOSCN/OSCN- in the range of pH 4-7 to eventually give simple inorganic anions including CN -, OCN-, SCN-, SO32-, and SO42-. Thiocyanogen ((SCN)2) is proposed to be a key intermediate in the hydrolysis; and the facile reaction of (SCN) 2 with OSCN- to give NCS(=O)SCN, a previously unknown reactive sulfur species, has been independently investigated. The mechanism of the aqueous decomposition of (SCN)2 around pH 4 is also reported. The resulting mechanistic models for the decomposition of HOSCN and (SCN) 2 address previous empirical observations, including the facts that the presence of SCN- and/or (SCN)2 decreases the stability of HOSCN/OSCN-, that radioisotopic labeling provided evidence that under physiological conditions decomposing OSCN- is not in equilibrium with (SCN)2 and SCN-, and that the hydrolysis of (SCN)2 near neutral pH does not produce OSCN-. Accordingly, we demonstrate that, during the human peroxidase-catalyzed oxidation of SCN-, (SCN)2 cannot be the precursor of the OSCN- that is produced.
Kinetics and mechanism of the comproportionation of hypothiocyanous acid and thiocyanate to give thiocyanogen in acidic aqueous solution
Nagy, Peter,Lemma, Kelemu,Ashby, Michael T.
, p. 285 - 292 (2008/10/09)
The kinetics of comproportionation of hypothiocyanous acid (HOSCN) and thiocyanate (SCN-) to give thiocyanogen ((SCN)2) in acidic aqueous solutions have been determined by double-mixing stopped-flow UV spectroscopy. Hypothiocyanite (OSCN-) was generated at pH 13 by oxidation of excess SCN- with hypobromite (OBr), followed by a pH jump to acidic conditions ([H+] = 0.20-0.46 M). The observed pseudo-first-order rate constants exhibit first-order dependencies on [H +] and [SCN-] with overall third-order kinetics. The corresponding kinetics of hydrolysis of (SCN)2 have also been examined. Under conditions of high (and constant) [H+] and [SCN -], the kinetics exhibit second-order behavior with respect to [(SCN)2] and complex inverse dependences on [H+] and [SCN-]. Under conditions of low [H+] and [SCN -], the kinetics exhibit first-order behavior with respect to [(SCN)2] and independence with respect to [H+] and [SCN-]. We attribute this behavior to a shift in the rate-limiting step from disproportionation of HOSCN (second-order dependency on [(SCN) 2]) to rate-limiting hydrolysis (first-order dependency on [(SCN)2]). Thus, we have determined the following equilibrium constant by the kinetic method: (SCN)2 + H2O ? HOSCN + SCN- + H+; Khyd = [HOSCN][SCN -][H+]/[(SCN)2] = Khyd/k comp = 19.8(±0.7) s-1/ 5.14(±0.07) × 103 M-2 s-1 = 3.9 × 10-3 M2.
Dinuclear zinc complexes of phenol-based "end-off" compartmental ligands: Synthesis, structures and phosphatase-like activity
Abe,Izumi,Ohba,Yokoyama,Okawa
, p. 85 - 95 (2007/10/03)
The phenol-based compartmental ligands of the "end-off" type, 2,6-bis{N-[2-(dimethylamino)ethyl]iminomethyl})-4-methylphenol (HL1), 2-{N-[2-(dimethylamino)ethyl]iminomethyl}-6-{N-methyl-N-[2-(dimethylamino) ethyl]aminomethyl}-4-bromophenol (HL2), 2,6-bis{2-[(2-pyridyl)ethyl]iminomethyl}-4-methylphenol (HL3) and 2-[N,N-di(2-pyridylmethyl)aminomethyl]-6-{N-[2-(dimethylamino)ethyl] iminomethyl}-4-methylphenol (HL4), have formed dinuclear zinc complexes: [Zn2(L1)(AcO)2]PF6 (1), [Zn2(L1)(NCS)3] (2), [Zn2(L2)(AcO)2]PF6 (3), [Zn2(L2)(NCS)3] (4), [Zn2(L3)-(AcO)2]PF6 (5), [Zn2(L3)(NCS)3] (6), [Zn2(L4)(AcO)2]C104 (7), [Zn2(L4)(AcO)(NCS)2] (8) and [Zn2(L4)(NCS)3] (9). The crystal structures of 1, 5·(DMF)0.5(2-PrOH)0.5, 7·CHCl3, 8·(2-PrOH) and 9·3CHCl3 have been determined. Complexes 1 and 5·(DMF)0.5(2-PrOH)0.5 have a di-μ-acetato-μ-phenolato-dizinc(II) core comprised of two square-pyramidal Zn centers. 7·CHCl3 has a similar dinuclear core, but it is comprised of one square-pyramidal Zn and one pseudo-octahedral Zn. 8·(2-PrOH) has a μ-acetato-μ-phenolato-dizinc(II) core with a unidentate thiocyanato-N group on each Zn. 9·3CHCl3 exists in two different crystals: one has a μ-thiocyanato-N-μ-phenolato-dizinc(II) core, whereas the other has a μ-phenolato-dizinc(II) core. The diacetato complexes, 1, 3, 5 and 7, are stable in solution. Hydrolytic activities of the complexes toward tris(p-nitrophenyl) phosphate (TNP) have been studied in aqueous DMF by means of UV-visible spectroscopic and 31P NMR methods. Complexes 1, 3 and 5 have an activity to hydrolyze TNP into bis(p-nitrophenyl) hydrogenphosphate (HBNP) in aqueous DMF. In contrast, 7 showed little hydrolytic activity toward TNP in aqueous DMF.
Temperature dependence of (SCN)2?- in water at 25-400°C: Absorption spectrum, equilibrium constant, and decay
Wu, Guozhong,Katsumura, Yosuke,Muroya, Yusa,Lin, Mingzhang,Morioka, Tomomi
, p. 4933 - 4939 (2007/10/03)
The temperature dependence of the absorption spectrum of the formation and decay of (SCN)2?-, a well-characterized dimer anion, was investigated at temperatures from 25 to 400°C. The absorption peak was found to shift to longer wavelength with temperature (red shift), from 470 nm at 25°C to 510 nm at 400°C. The equilibrium constants K1 and K2 for the reactions SCNOH?- SCN? + OH- and SCN? + SCN- ? (SCN)2?-, respectively, were found to decrease with temperature. Due to the considerable decrease of K2 with temperature, a rise in temperature shifts the reaction in favor of SCN?, so the observed yield of (SCN)2?- at high temperatures is strongly dependent on the SCN- concentration. As the SCN? concentration could be as high as or even higher than the (SCN)2?- concentration at high temperatures, a pseudo-first-order decay of SCN? has to be taken into consideration to account for the overall decay of (SCN)2?-. Using the kinetic parameters obtained in this work and available in the literature, the decay profiles of (SCN)2?- can be well reproduced for any temperature and KSCN concentration considered. A combination of the simulation and the experimental results reveals a decrease of ∈max of (SCN)2?- with temperature; the degree is ～30percent for a rise from 25 to 400°C.
Thiocyanogen as an intermediate in the oxidation of thiocyanate by hydrogen peroxide in acidic aqueous solution
Figlar,Stanbury
, p. 5089 - 5094 (2008/10/08)
The kinetics of the reaction of H2O2 with excess SCN- in acidic media was studied by use of Ti(IV) as an indicator for the concentration of H2O2. Pseudo-first-order behavior was realized by this method, and these data confirm the acid-catalyzed rate law and rate constant reported some 40 years ago for this reaction under conditions of excess H2O2. Under the same conditions except without Ti(IV), repetitive-scan spectra reveal the formation and decay of an intermediate that absorbs in the UV. In the proposed mechanism, HOSCN is produced in the first step and it is converted rapidly to (SCN)2 through its equilibrium reaction with SCN-. The observed intermediate is believed to be (SCN)2, which decays on a longer time scale. Excellent global fits of this mechanism to the repetitive-scan data are obtained with rate constants constrained by the Ti(IV) data and published previously in our study of the ClO2/SCN- reaction. These fits yield a spectrum for (SCN)2 that is characterized by λ(max) = 297 nm and ε297 = 147.M-1 cm-1, in fine agreement with our prior report.
Substitution kinetics of the aqua ligand in [Re(NO)(H2O)(CN)4]2- by the monodentate nucleophiles SCN-, N3- and thiourea and the X-ray crystal structure of (AsPh4)2[Re(NO)(SC(NH2)2)(CN) 4]
Smith, John,Purcell, Walter,Lamprecht, Gert J.,Roodt, Andreas
, p. 1389 - 1395 (2008/10/09)
The substitution reactions between [Re(NO)(H2O)(CN)4]2- and the nucleophiles SCN-, N3- and thiourea revealed that both the aqua and the hydroxo ligands are substituted with respective rate constants of 3.6(1) × 10-3 and 1.57(5) × 10-3 M-1 s-1 at 40°C in the case of SCN-. The pKa1 was spectrophotometrically determined as 9.90(2) at 25°C and kinetically as 9.50(4) at 40°C with NCS- as the incoming nucleophile. The (AsPh4)2[Re(NO)(SC(NH2)2)(CN) 4] complex was isolated as the product for the reaction between [Re(NO)(H2O)(CN)4]2- and thiourea and its X-ray crystal structure determined. The Re - NO and N - O bond lengths are 1.736(11) and 1.146(13) A, respectively, while the Re - S bond distance is 2.503(4) A. The thiourea is bonded cis with respect to the nitrosyl group.
