Kinetics and Mechanism of Formation and Acid–Catalyzed Decomposition of the [Co(NH3)4CO3]+ Complex Cation in Aqueous Solution

It has been found that the kinetics of acid‐catalyzed hydrolysis of the [Co(NH₃)₄CO₃]⁺ cation follows the rate law –d ln [complex]/d t = k₁K[H⁺]/(1+K[H⁺]) (5 °C < T < 25 °C; 0.0543M < [HClO₄] < 2.7M and I = 1.0M (NaClO₄). The reaction course consists of a rapid pre‐equlibrium protonation followed by a rate determining ring opening process and the subsequent fast release of monodentate carbonato ligand. The changes of the absorbance for the acidic aqueous solution of the [Co(NH₃)₄CO₃]⁺ complex ion proceeded at relevant wavelength in the UV‐Vis region and time course of these changes were analysed according to a programme “Glint” for the consecutive first – order reaction with two experimental rate constants k_fast and k_slow. Finally, the aquation mechanism has been proposed and the effect of ligand coordination mode (bidentate carbonato anion) on complex reactivity has been discussed.     

Proton magnetic resonance studies of compounds with bridgehead nitrogen atoms—XX: The NMR spectra and stereochemistry of some hexahydropyrido[2, 1-c] [1, 4] oxazin-3(4H)-ones and related compounds

A series of substituted hexahydropyrido [2,1-c] [1,4] oxazin-3(4H)-ones has been synthesised, and the configurations of these bicyclic lactones assigned utilising chemical and spectral data. All the compounds adopt trans-fused conformations and the conformation of the lactone ring is discussed with reference to the magnitude of the geminal coupling constant of the N? CH₂? C(O)? O protons, and the vicinal couplings between the angular proton and the methylene protons adjacent to the ring oxygen atom. The lactone ring conformation is shown to differ slightly from the half chair conformation described for some monocyclic δ -lactones. The synthesis and NMR spectra of some related compounds possessing the bridgehead N? CH₂? C(O)? O system are discussed and these compounds are also shown to adopt a trans-fused ring conformation.     

SrPtIn,Sr2Pt3In4, and Ca2Au3In4 – Alkaline Earth Compounds with Complex Three-Dimensional [PtIn], [Pt3In4], and [Au3In4] Polyanions

Single phase SrPtIn, Sr₂Pt₃In₄ and Ca₂Au₃In₄ were prepared by high-frequency melting of the elements in water-cooled glassy carbon crucibles. X-ray diffraction of powders and single crystals yielded Pnma, oP12, a = 758.57(9) pm, b = 451.52(6) pm, c = 846.0(2) pm, wR2 = 0.0937, 467 F² values, 20 variables for SrPtIn, P62m, hP36, a = 1465.9(2) pm, c = 448.24(6) pm, wR2 = 0.0722, 1059 F² values, 44 variables for Sr₂Pt₃In₄ and Pnma, oP36, a = 1463.6(4) pm, b = 443.23(9) pm, c = 1272.3(2) pm, wR2 = 0.0694, 1344 F² values, 56 variables for Ca₂Au₃In₄. SrPtIn adopts the TiNiSi type structure. The indium atoms have a distorted tetrahedral platinum coordination. These InPt_4/4 tetrahedra are edge- and corner-shared, forming a three-dimensional [PtIn] polyanion in which the strontium atoms are embedded. Sr₂Pt₃In₄ crystallizes with the Hf₂Co₄P₃ type structure with the more electronegative platinum atoms occupying the phosphorus sites while the indium atoms are located on the cobalt positions. Ca₂Au₃In₄ is a new site occupancy variant of the YCo₅P₃ type. Gold atoms occupy the phosphorus sites and indium the cobalt sites, but one cobalt site is occupied by calcium atoms leading to the composition Ca₂Au₃In₄. Common geometrical motifs of both structures are condensed, platinum(gold)-centered trigonal prisms formed by the alkaline earth and indium atoms. The platinum (gold) and indium atoms form complex three-dimensional [Pt₃In₄] and [Au₃In₄] polyanions, respectively. The alkaline earth cations are located in distorted hexagonal tubes.     

3He NMR studies on helium–pyrrole,helium–indole,and helium–carbazole systems: a new tool for following chemistry of heterocyclic compounds

The ³He nuclear magnetic shieldings were calculated for free helium atom and He–pyrrole, He–indole, and He–carbazole complexes. Several levels of theory, including Hartree–Fock (HF), Second‐order Møller‐Plesset Perturbation Theory (MP2), and Density Functional Theory (DFT) (VSXC, M062X, APFD, BHandHLYP, and mPW1PW91), combined with polarization‐consistent pcS‐2 and aug‐pcS‐2 basis sets were employed. Gauge‐including atomic orbital (GIAO) calculated ³He nuclear magnetic shieldings reproduced accurately previously reported theoretical values for helium gas. ³He nuclear magnetic shieldings and energy changes as result of single helium atom approaching to the five‐membered ring of pyrrole, indole, and carbazole were tested. It was observed that ³He NMR parameters of single helium atom, calculated at various levels of theory (HF, MP2, and DFT) are sensitive to the presence of heteroatomic rings. The helium atom was insensitive to the studied molecules at distances above 5 Å. Our results, obtained with BHandHLYP method, predicted fairly accurately the He–pyrrole plane separation of 3.15 Å (close to 3.24 Å, calculated by MP2) and yielded a sizable ³He NMR chemical shift (about ?1.5 ppm). The changes of calculated nucleus‐independent chemical shifts (NICS) with the distance above the rings showed a very similar pattern to helium‐3 NMR chemical shift. The ring currents above the five‐membered rings were seen by helium magnetic probe to about 5 Å above the ring planes verified by the calculated NICS index. Copyright © 2014 John Wiley & Sons, Ltd.     

PtCl3(C2H4)]-[AmH]+ complexes containing chiral secondary amines: use as chiral derivatizing agents for the enantiodiscrimination of unsaturated compounds by 195Pt NMR spectroscopy and NMR stereochemical investigation.

Ionic complexes [PtCl3(C2H4)]-[AmH]+, containing chiral secondary amines, constitute a versatile class of chiral derivatizing agents (CDAs) for the enantiomeric purity determination of chiral unsaturated compounds via 195Pt NMR spectroscopy. The NMR conformational analysis allows us to search for the stereochemical basis of their enhanced versatility.     

31P solid state NMR studies of metal selenophosphates containing [P2Se6]4-, [P4Se10]4-, [PSe4]3-, [P2Se7]4-, and [P2Se9]4- ligands

31P solid-state nuclear magnetic resonance (NMR) spectra of 12 metal-containing selenophosphates have been examined to distinguish between the [P(2)Se(6)](4-), [PSe(4)](3-), [P(4)Se(10)](4-), [P(2)Se(7)](4-), and [P(2)Se(9)](4-) anions. There is a general correlation between the chemical shifts (CSs) of anions and the presence of a P[bond]P. The [P(2)Se(6)](4-) and [P(4)Se(10)](4-) anions both contain a P[bond]P and resonate between 25 and 95 ppm whereas the [PSe(4)](3-), [P(2)Se(7)](4-), and [P(2)Se(9)](4-) anions do not contain a P[bond]P and resonate between -115 and -30 ppm. The chemical shift anisotropies (CSAs) of compounds containing [PSe(4)](3-) anions are less than 80 ppm, which is significantly smaller than the CSAs of any of the other anions (range: 135-275 ppm). The smaller CSAs of the [PSe(4)](3-) anion are likely due to the unique local tetrahedral symmetry of this anion. Spin-lattice relaxation times (T(1)) have been determined for the solid compounds and vary between 20 and 3000 s. Unlike the CS, T(1) does not appear to correlate with P-P bonding. (31)P NMR is also shown to be a good method for impurity detection and identification in the solid compounds. The results of this study suggest that (31)P NMR will be a useful tool for anion identification and quantitation in high-temperature melts.     

Comparative study of vibrational spectra of Rb4LiH3(SO4)4, K4LiH3(SO4)4, K4LiH3(SeO4)4, Na5H3(SeO4)4.2H2O and Na2SeO4.H2SeO3.H2O crystals. Polarized infrared and Raman studies

Vibrational spectra of M4LiH3(XO4)4 family, where M=K, Rb, X=S, Se together with Na5H3(SeO4)4.2H2O and Na2SeO4.H2SeO3.H2O crystals were compared. Similarities and differences are described. The spectroscopic manifestation of the presence of hydrogen bonds is discussed. Position of the bands corresponding to bending type of vibrations (in-plane and out-of plane) of hydrogen bonds is analyzed in the function of temperature. Small dynamic splitting of the bands due to weak interactions between ions is noticed.     

Preparation,Structure and Properties of the One-Dimensional Polymeric Complex Na2[AlW3O4(O2CEt)8]2

Abstract

The heterometallic polymeric cluster Na₂[AlW₃O₄ (O₂CEt)₈]₂ (1) has been prepared by reaction of W(CO)₆ and NaWO₄·2H₂O with AlCl₃ at 120°C in propionic anhydride and characterized by X-ray crystallography, with the following crystal data: triclinic, space group P1, a = 12.205(5), b = 13.032(4), c = 13.925(3) Å, α = 90.21(3)°, β = 109.53(5)°, γ = 117.26(6)°, V = 1822.8(1)ų, Z = 1, R = 0.038 and R_w = 0.101. The structure consists of two triangular [W₃O₄(O₂CEt)₈]^4? cluster unit, which act as polydenate ligands to link Al³⁺ and Na⁺ ions forming a one–dimensional chain structure. IR spectra show characteristic [W₃O₄]⁴⁺ bands at 746–815 cm^?1. Thermal analysis reveals that the complex is air stable up to 250°C. Cluster 1 decomposes in hot aqueous 2 M HCl solution to produce discrete [W₃O₄]⁴⁺ units.     

Chemotherapeutic agents. IX. Synthesis and pesticidal activities of bis[4-aryl/alkyl-1, 2, 4-triazoline-5-thione-3-yl]alkanes and 1 -Aryl/alkyl-3-[4-(4-aryl/alkyl-1, 2, 4-triazoline-5-thione-3-yl)phenyl]thiourea and related compounds

Various bis[4-aryl/alkyl-1, 2, 4-triazoline-5-thione-3-yl]alkanes ( 3 ) were prepared from base cyclization of bis thiosemicarbazide 2 and transformed into sulphides by reaction with different alkyl halides in alkaline medium. These compounds were further oxidised to sulphones 5 with acidic potassium permanganate. 1-Aryl-3-[4-(4-aryl/alkyl-1, 2, 4-triazoline-3-thione-5-yl)phenyl]thioureas ( 8 ) were prepared in two steps from p-aminophenylhydrazide ( 6 ) and aryl/alkylisothiocyanates. Alkylation of 8 with different alkyl halides yielded exclusively sulphides 9 . Some sulphides 12 and Mannich bases 13 from 5-(p-fluorophenyl)-1, 3, 4-oxadiazol-2-thione ( 11 ) were also prepared to evaluate their pesticidal activities. All the prepared compounds were screened for pesticidal activities but none of them exhibited any significant activity.     

Macro-, Micro-, Nano- and Crystal Structures of a Homodinuclear Complex [NH3（ CH2）3NH3]2{Na2[（C6H4O2）2]（C6H4O2H）2}

A homodinuclear complex （NH3CH2CH2CH2NH3）2 {Na2[（C6H4O2）2] （C6H4O2H）2} （1） has been synthesized by a solution-based self-assembly route. It crystallized in monoclinic system with space group P21/c. Every sodium ion coordinates in a tetragonal prism fashion with two O atoms of a terminal chelating catecholate ligand and three O atoms from two bridging catecholate ligands. Two neighboring NaO5 tetragonal prisms are edge-shared and centrosymmetric with regard to the inversion center to form a binuclear cluster {Na2[（C6H4O2）2]（C6H4OOH）2}^4- anion. The complex anions were aligned parallelly by n-n interaction and linked with the protonated 1,3-propylenediamine through hydrogen bonds which were assembled into a multi-lamellar structure with channels. The crystal exhibits rectangular geometry with an interior triangle hollow structure under optical microscopy. And the scanning electron microscopy （SEM） indicates that the wall of the tubes shows multi-lamella morphologies. Further, the transmission electron microscopy （TEM） reveals that the crystal is composed of multi-lamellar nano-tubes with diameters less than 100 nm. The molecular structure of the complex was compared with that of its isomer complex 2.     

Mercury-199 NMR studies of thiacrown and related macrocyclic complexes: the crystal structures of [Hg(18S6)](PF6)2 and [Hg(9N3)2](ClO4)2

We wish to report the first measurements of (199)Hg NMR chemical shift data for a series of homoleptic Hg(II) complexes with thiacrown ligands and related aza and mixed thia/aza macrocycles. In mercury(II) complexes containing trithiacrown through hexathiacrown ligands, we observed (199)Hg NMR chemical shifts in the range of -298 to -1400 ppm. Upfield chemical shifts in these NMR spectra are seen whenever (a) the number of thioether sulfur donors in the complex is decreased, (b) a thioether sulfur donor is replaced by a secondary nitrogen donor, and (c) the size of the macrocycle ring increases without a change in the nature or number of the donor atoms. Changes in noncoordinating anions, such as hexafluorophosphate and perchlorate, have little effect on the (199)Hg chemical shift. For several complexes, we observed (3)J((199)Hg-(1)H) coupling in the range of 50-100 Hz, the first example of proton-mercury coupling through a C-S thioether bond. Also, we obtained unusual upfield (13)C NMR chemical shifts for methylene resonances in several of the thiacrown complexes which correspond to distortions within the five- and six-membered chelate rings bound to the mercury ion. We report the X-ray crystal structure of the complex [Hg(18S6)](PF(6))(2) (18S6 = 1,4,7,10,13,16-hexathiacyclooctadecane). The molecule crystallizes in the rare trigonal space group Pm1 with hexakis(thioether) coordination around the Hg(II) center confirming previous X-ray photoemission spectroscopic data on the compound. The lack of an observable (199)Hg NMR signal for the complex is the result of the identical length (2.689(2) Angstroms) of all six Hg-S bonds. We additionally report the X-ray structure of the complex [Hg(9N3)(2)](ClO(4))(2) (9N3 = 1,4,7-triazacyclononane) which shows hexakis(amine) coordination of the 9N3 to form a distorted trigonal prismatic structure. Solution dissociation of the one of the 9N3 ligands from the mercury ion is confirmed by multinuclear NMR experiments. For six-coordinate macrocyclic Hg(II) complexes, N6 donor sets have a preference for trigonal prisms while S6 donor sets favor octahedral structures.     

Syntheses of benzomorphan and related compounds. Part 1. Synthesis of N-substituted-l,2,3,4,5,6-hexahydro-8-hydroxy-2,6-methano-6,11-dimethyl-3-benzazocine [studies on the syntheses of heterocyclic compounds. Part CCLXXXII ]

A modified synthesis of pentazocine, l,2,3,4,5,6-hexahydro-8-hydroxy-2,6-methano-6, H-dimethyl-3-(3-methyl-2-butenyl)-3-benzazocine (III), has been achieved and catalytic hydro-genation has been found to be effective for the debenzylation of quaternary ammonium salts.     

Proton magnetic resonance studies of compounds with bridgehead nitrogen atoms: XXXII—The 1H n.m.r. spectra and stereochemistry of 4-aryl-1,6,7,11b-tetrahydro-2H,4H-[1,3]oxazino[4,3-a]isoquinoline, 4-aryl-1,2,6,7,12,12b-hexahydro-4H-[1,3]oxazino[3′,4′:1,2]pyrido[3,4-b]indole and of related systems

cis(4-H,11b-H)-4-Aryl-1,6,7,11b-tetrahydro-2H,4H-[1,3]oxazino [4,3-a]isoquinoline and the related thiazino compound preferentially adopt in solution the O (or S) inside cis-conformation in contrast to cis(1-H,4a-H)-1-arylperhydropyrido[1,2-c][1,3]oxazine which adopts the trans fused conformation. 1-(β-Hydroxy-ethyl)-1,2,3,4-tetrahydro-β-carboline condenses with benzaldehyde to give the 1,3-oxazine derivative rather than the dimeric structure reported in the literature.     

Spectral, analytical, thermal, and antimicrobial studies of novel sodium 2-[4(2-hydroxy-3-izopropylaminopropoxy)phenyl]acetamide (atenolol) dithiocarbamate and its divalent transition metal complexes

Atenolol dithiocarbamate (ADTC) and its complexes with Cu(II), Co(II), Ni(II), Zn(II), and Cd(II) have been synthesized. These newly synthesized products have been characterized by elemental analyses (C, H, N, and S), thermal (thermogravimetry (TG) and differential thermal analyses (DTA)) as well as by spectral (UV, IR, and NMR (¹H)) studies. The stability constants (β) of metal complexes of ADTC have been determined by UV-Vis data in solutions in DMSO. The antimicrobial activities of the metal complexes have been screened in vitro against ten bacteria. The text was submitted by the authors in English.     

Aqueous spray-drying synthesis of alluaudite Na2+2xFe2−x(SO4)3 sodium insertion material: studies of electrochemical activity,thermodynamic stability,and humidity-induced phase transition

Journal of Solid State Electrochemistry - In pursuit of high-energy density sodium insertion materials, polyanionic frameworks can be designed with tuneable high-voltage operation stemming from...     

NMR 3J(C1,H3) couplings in 1‐X‐bicyclo[1.1.1]pentanes. FPT–DFT and NBO studies of hyperconjugative interactions and heavy atom substituent effects

In this work a rationalization of the very large substituent effects on ³J(C₁,H₃) couplings in 1‐X‐bicyclo[1.1.1]pentanes is presented. The Fermi contact contribution to such couplings was calculated in a series of 13 X‐derivatives within the DFT–B3LYP framework using the finite perturbation theory. Core electrons for atoms beyond the Second Row were taken into account using effective core potentials. Calculated couplings are in very good agreement with experimental values. The role played by hyperconjugative interactions involving bonds or antibonds belonging to the coupling pathway are studied using the NBO approach. Heavy atom contribution to substituent effects on ³J(C₁,H₃) couplings was estimated as small. This contrasts notably with trends observed in the corresponding ¹³C substituent chemical shifts, SCSs. The latter were estimated comparing for X=Cl, Br, I, SnMe₃, calculated SCSs with their experimental values. Such estimations are in line with explicit calculations of the spin‐orbit contribution reported in the literature for smaller compounds. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 1615–1621, 2001     

The role of the atomic charges on the ligands and platinum(II) in affecting the cis and trans influences in [PtXL(PPh3)2]+ complexes (X = NO3, Cl, Br, I; L = 4-substituted pyridines, amines, PPh3). A 31P NMR and DFT investigation

One bond Pt-P coupling constants (1)J(PtP) of a series of cationic complexes [PtXL(PPh(3))(2)](+) (X = NO(3), Cl, Br, I; L = 4-Z-pyridines, Z = electron withdrawing or releasing groups, 4a-k; or X = Cl, L = NH(3), PhCH(2)NH(2) and (i)PrNH(2), 5a-c) have been used to establish the trans and cis influence sequences of X and pyridines. The crystal structure of compound 4f(BF(4)) with Z = (t)Bu has been resolved. In the pyridine complexes 4a-d (Z = H, variable X), both the trans and cis influence series of the anionic ligands X decrease along the same sequence I > Br > Cl > NO(3), as previously found for [PtX(PPh(3))(3)](+) (X = NO(3), Cl, Br, I, 3a-d), however in 4a-d the cis influence turns out to be more important than the trans. On the contrary, in [PtCl(4-Z-py)(PPh(3))(2)](+) (4b,e-k) the sequence of the trans influence of the 4-Z-pyridines is opposite to that of the cis, the latter being Z = CN > CHO > Br > PhCO > H > Me > (t)Bu > NH(2), i.e. the most basic pyridine gives rise to the lowest cis influence. This correlation was found to hold also for complexes 5a-c (L = amines). All the observed trends have been fully reproduced by B3LYP/def2-SVP DFT calculations, by looking at the relevant optimized bond lengths of selected complexes of type 3, 4 and 5. Subsequent evaluation of the atomic charges, by resorting to two independent methods, i.e., the Natural Bond Order analysis of the wavefunction and the Bader's Quantum Theory of Atoms in Molecules, allowed for rationalization of the origin of the cis and trans influences. The negative charge on the nitrogen atoms of free pyridines becomes more negative upon protonation and even more so when coordinated to the [PtCl(PPh(3))(2)](+) moiety. The least negatively charged nitrogen atom of coordinated pyridines is that of 4-CN-py (the highest cis influencing pyridine derivative), which gives rise to the lowest positive charge on Pt, confirming the relationship between the lowering of the charge on the metal ion and a high cis influence. The trans influence can be described in terms of competition between the charges on the two trans donor atoms. In contrast with the behaviour of pyridines, the positive charge on the phosphorous atom of free PPh(3) increases upon coordination to Pt(II), moreover the PPh(3) ligands acquire a substantial positive charge, thus efficiently delocalising the charge of the cationic complex.     

The reaction between 3,3-bis(methoxyphenyl)-3H-naphtho[2,1-b]pyran and 1,3-bis(methoxyphenyl)-1H-naphtho[2,1-b]pyran, 2,2-diphenyl-2H-chromen and 2,4-diphenyl-4H-chromen,and related compounds

The reaction between 3,3-bis(methoxyphenyl)-3H-naphtho[2,1-b]pyran and 1,3-bis(methoxyphenyl)-1H-naphtho[2,1-b]pyran under acid conditions gives a 7a,15a-dihydro-7a,15-bis(methoxyphenyl)-16-[2,2-bis(methoxyphenyl)-l-vinyl]dinaphtho-[2,1-b:2,1-g]-4H,5H-pyrano[2,3-b]-pyran.