Palladium(II) compounds with planar chirality. X-Ray crystal structures of (+)-(R)-[{(η5-C5H4)–CHN–CH(Me)–C10H7}Fe(η5-C5H5)] and (+)-(Rp,R)-[Pd{[(Et–CC–Et)2(η5-C5H3)–CHN–CH(Me)–C10H7]Fe(η5-C5H5)}Cl]

A wide variety of planar chiral cyclopalladated compounds of general formulae [Pd{[(η⁵-C₅H₃)–CHN–CH(Me)–C₁₀H₇]Fe(η⁵-C₅H₅)}Cl(L)] (with L=py-d₅ or PPh₃), [Pd{[(η⁵-C₅H₃)–CHN–CH(Me)–C₁₀H₇]Fe(η⁵-C₅H₅)}(acac)] or [Pd{[(R¹–CC–R²)₂(η⁵-C₅H₃)–CHN–CH(Me)–C₁₀H₇]Fe(η⁵-C₅H₅)}Cl] (with R¹=R²=Et; R¹=Me, R²=Ph; R¹=H, R²=Ph; R¹=R²=Ph; R¹=R²=CO₂Me or R¹=CO₂Et, R²=Ph) are reported. The diastereomers {(R_p,R) and (S_p,R)} of these compounds have been isolated by either column chromatography or fractional crystallization. The free ligand (R)-(+)-[{(η⁵-C₅H₄)–CHN–CH(Me)–C₁₀H₇}Fe(η⁵–C₅H₅)] (1) and compound (+)-(R_p,R)-[Pd{[(Et–CC–Et)₂(η⁵-C₅H₃)–CHN–CH(Me)–C₁₀H₇]Fe(η⁵-C₅H₅)}Cl] (7a) have also been characterized by X-ray diffraction. Electrochemical studies based on cyclic voltammetries of all the compounds are also reported.     

1H-, 13C-UND 31P-NMR-SPEKTROSKOPISCHE UNTERSUCHUNGEN AN BIS-(DIALKOXYTHIOPHOSPHORYL)-UND-(DIALKOXYPHOSPHORYL)-SULFANEN UND-POLYSULFANEN

Abstract

Compounds of the following structure

(R¹O)₂(X)P[sbnd]Y–P(X)(OR²)₂

(X = O, Y = S_n (n = 1–4), R¹ = R² = Me, iPr;

X = S, Y = S_n (n = 1–4), R¹, R² = Me, Et, iPr, iBu;

X = S, Y = S-Se-S, S-Te-S, R¹ = R² = Me

were prepared and their NMR spectra were analysed. Depending on the number of sulfur atoms, bonded between the phosphorus atoms, typical ranges of the P-P coupling constants were found for the different sulfanes investigated: ²J_PP from-10 to-20 Hz, ³J_PP less than 3 Hz, ⁴J_PP from +10 to +13 Hz and ⁵J_PP less than 1 Hz. For the small vicinal coupling constants and the relatively large values of ⁴J_PP different possibilities of their interpretation are given.     

N–O-Bindungsspaltung in O-silylierten Oximen bei der Reaktion mit einem Titanocen-Alkin-Komplex

N–O Bond Cleavage in O-silylated Oximes by Reaction with a Titanocene-Alkyne Complex Cp₂Ti(Me₃SiC₂SiMe₃) 1 reacts with alicyclic and aliphatic O-silylated ketoximes of type R¹R²C=NOSiMe₃ ( 2 : R¹R² = (CH₂)₅; 3 : R¹ = R² = Me) under N–O bond breaking to the titanocene complexes Cp₂Ti(OSiMe₃)(N=CR¹R²) 6 (R¹R² = (CH₂)₅) and 7 (R¹ = R² = Me). The structure of 6 was obtained by X-ray crystal structure analysis ( 6 : triclinic, space group P1, Z = 2, a = 9.486(1), b = 9.865(1), c = 12.305(2) Å, α = 107.19(1), β = 96.08(1), γ = 111.08(1)°).     

Synthese und spektroskopische Charakterisierung einiger Pentacarbonylwolfram(0)‐Komplexe mit monound bicyclischen Phosphiran‐Liganden: Kristallstruktur von [{(Me3Si)2HCPC(H)H–C(H)Ph}W(CO)5]

Synthesis and Spectroscopic Characterisation of some Pentacarbonyltungsten(0) Complexes with Mono‐ and Bicyclic Phosphirane Ligands: Crystal Structure of [{(Me₃Si)₂HCPC(H)H–C(H)Ph}W(CO)₅] The tungsten(0) complex [{(Me₃Si)₂HCPC(Ph)=N}W(CO)₅] ( 1 ) reacts upon heating with alkene derivatives 2 , 6 , 8 , and 10 in toluene to form benzonitrile and the complexes [{(Me₃Si)₂HCPC(R¹,R²)–C(R³,R⁴}W(CO)₅] ( 4 , 7 a , b , 9 a , b , 11 a , b ) ( 4 (trans): R¹,R³ = Ph, R²,R⁴ = H, 7 a , b (cis, meso and rac): R¹,R³ = Ph, R²,R⁴ = H, 9 a , b (RR und SS): R¹ = Ph, R²,R³,R⁴ = H, 11 a , b : R¹=R³ = (CH₂)₄, R²,R⁴ = H). Spectroscopic and mass spectrometric data are discussed. The structure of the complex 9 a was determined by X‐ray single crystal structure analysis showing characteristic data for the phosphirane ring such as a narrow angle at phosphorus (49,2(2)°), different P–C distances (P–C(6) 182,1(5) and P–C(7) 185,2(4) pm) and 152,9(6) pm for the basal C–C bond.     

Metal Ions in Biological Systems: Vol. 11: Metal Complexes as Anticancer Agents.: General Editor: Helmut Sigel,multi-author work as listed below. Marcel Dekker,Inc., New York, 1980, xx + 427 pages,S.Fr.115 (≈£35), ISBN 0-8247-1004-5.

Treatment of methylene dioximes (I) with palladium(II) chloride gives [(R¹R²C=NO)₂CH₂]PdCl₂ (II), their ¹H NMR spectra exhibit resonances due to one of the methylene protons in remarkably lower fields (σ 8.99—8.28 ppm). X-ray analysis of IIb (R¹ = R² = n-Pr) shows that the ligand has boat-like conformation in which the distance between the Pd and the H atom of the OCH₂O-group is 2.46 Å, being much less than expected for the sum of the Van der Waals radii.     

Synthesis and Structural Investigation of Brightly Colored Organoammonium Violurates

Nine new organoammonium violurates [R¹R²R³NH][C₄H₂N₃O₄] [R¹ = R² = H, R³ = c‐C₃H₅ ( 2 ), R³ = tBu ( 3 ), R³ = adamantyl ( 4 ), R³ = C₆H₂Me₂‐4,5‐NH₂‐2 ( 5 ); R¹ = H, R² = R³ = Et ( 6 ), iPr ( 7 ); R¹ = H, R²/R³ = (–CH₂–)₄ ( 8 ); R¹ = R² = R³ = Et ( 9 ); R¹ = R² = Me, R³ = (CH₂)₂NMe₂ ( 10 )] were prepared by treatment of violuric acid ( 1 ) with a variety of primary, secondary, and tertiary amines. With the exception of orange 5 , all these violurate salts form bright blue or blue‐purple crystalline solids. The acidic triethylammonium violurate [NHEt₃]H[C₄H₂N₃O₄]₂ · H₂O ( 9a ) was isolated in the form of red‐violet, plate‐like crystals by the reaction of violuric acid hydrate with triethylamine in a molar ratio of 2:1 in ethanol. All compounds were fully characterized by their IR and NMR (¹H, ¹³C) data as well as elemental analyses. X‐ray crystal structures determinations of 2 , 7 , and 9a revealed supramolecular self‐assembly through networks of N–H ··· N and N–H ··· O hydrogen bonds in the crystalline state.     

Diorganophosphinoalkyl-dimethylzinnchloride: Synthese,struktur und reaktionsverhalten

Phosphinoalkylchlorostannanes of the type Me₂Sn(Cl)(CH₂)_nPR¹R² (n = 2,3) (I–VIII) are synthesized by a redistribution reaction of the tetraorganostannanes Me₃Sn(CH₂)_nPR¹R² (n = 2,3) with trimethyltin chloride. In non-coordinating solvents the tin atom in I–IV is tetracoordinated, whereas NMR data indicate an intramolecular SnP interaction for V–VIII. In the solid state compound III exists as an 1:1 adduct with trimethyltin chloride. With methyl iodide compounds I–VIII form the phosphonium stannates Me₂SnCl) (I) (CH₂)_nP+R¹R²Me (XI–XIII). Compounds I–VIII are suitable starting materials for the synthesis of the tin hydrides Me₂Sn(H)(CH₂)_nPR¹R² (XIV–XVI) and the distannanes [Me₂Sn(CH₂)_nPR¹R²]₂ (XVII–XIX). The reaction of I–VIII with sodium in liquid ammonia or with lithium in THF, respectively, yields solutions of the corresponding alkali stannides Me₂Sn(M)(CH₂)_nPR¹R² (M = Li, Na).     

Nucleophilic substitution reactions of acetylides on substituted tricarbonyl(η6-fluoroarene)chromium and reactions of tricarbonyl[η6-(2-trimethylsilylethynyl)toluene]chromium and tricarbonyl[η6-(p-ethynyl-phenylethynyl)benzene]chromium with dicobalt octacarbonyl

Nucleophilic substitution reactions of various acetylides on substituted tricarbonyl(η⁶-fluoroarene)chromiums were pursued. The reaction presumably underwent a more complicated mechanism rather than the direct substitution on the fluorine-bearing carbon. The organometallic compounds (η⁶-C₆H₃R¹R²R³)Cr(CO)₃ (R¹: CC–C₆H₄CH₃, R²: o-Me, R³: H (5a), R¹: CC–C₆H₄CH₃, R²: o-OMe, R³: H (6a), R¹: CC–C₆H₄CH₃, R²: m-OMe, R³: H (6b), R¹: CCPh, R²: o-Me, R³: o-OMe (8b), R¹: CCPh, R²: m-Me, R³: m-OMe (8c), R¹: CCSiMe₃, R²: o-Me, R³: H (9a), R¹: CC–C₆H₄CCH, R²: H, R³: H (12), R¹: CC–C₆H₄CCH, R²: o-Me, R³: H (13)) as well as the organometallic dimmer [{(η⁶-o-Me-C₆H₄)Cr(CO)₃(di-ethynyl)] (di-ethynyl: CC–C₆H₄CC (14)) have been synthesized from nucleophilic substitution reactions of tricarbonyl(η⁶-fluoroarene)(chromium) compounds with suitable acetylides. The products have been characterized by spectroscopic means. In addition, (8b) and (8c) were characterized by X-ray diffraction studies. Further reactions of (9a) and (12) with appropriate amount of Co₂(CO)₈ yielded μ-alkyne bridged bimetallic complexes, Co₂(CO)₆{μ-Me₃SiCC–(o-tolueneCr(CO)₃} (10) and (Co₂(CO)₆)₂{μ-HCC–C₆H₄–CC–(benzene)Cr(CO)₃)}(15), respectively. Both (10) and (15) were characterized by spectroscopic means as well as single crystal X-ray crystallography. The core of these molecules is quasi-tetrahedron containing a Co₂C₂ unit. A two-dicobalt-fragments coordinated di-enyls complex, (Co₂(CO)₆)₂{μ-HCC–C₆H₄–CC–H} (17), was synthesized from the reaction of 1,3-diethynylbenzene with Co₂(CO)₈. Crystallographic studies of (17) also show that it exhibits a distorted Co₂C₂ quasi-tetrahedral geometry.     

Preparation of poly(biphenylene vinylene) type polymers by Ni‐promoted polycondensation and their basic optical properties

Ni(0)‐complex promoted dehalogenation polymerization of 1,2‐bis(4‐bromophenyl)ethylene derivatives gave poly(p‐biphenylene vinylene) type polymers, [—C₆H₂R—CR² = CR²—C₆H₂R—)_n (P(R¹,H) and P(H,R²) ], having substituents (R¹ = Me, Et, CHMe₂, and n‐C₈H₁₇, R² = Me, Et, n‐C₆H₁₃, n‐C₁₁H₂₃, and Ph) at the benzene ring or vinylene group in 90–99% yields. The polymers were soluble in organic solvents such as CHCl₃, dimethylformamide, and tetrahydrofuran, and gave M_n of 2.4–5.3 × 10³ in gel permeation chromatography analysis. The absorption peak of the polymers appeared at a longer wavelength than that of the corresponding monomers by about 30 nm due to the expansion of the π‐conjugation system. The polymers were photoluminescent in solutions and in their films, emitting blue or green light. P(R¹,H)s gave higher quantum yields (Φ = 0.35–0.51) than P(H,R²) s in CHCl₃. P(H,R²) s showed a large Stokes shift (9600–13,500 cm⁻¹) in their photoluminescence. Single‐layer and multilayer light emitting diodes using vacuum deposited thin film of P(H,Ph) were prepared. Polymers with long alkyl substituents formed an ordered structure in the solid state as judged from their XRD patterns. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1493–1504, 2000     

Elementorganische Amin/Imin-Verbindungen,XXXI. Cyclometallierung bei N-tert-Butyl-Phosphor-Stickstoff-Iridiumkomplexen

Element-Organic Amine/Imine Compounds, XXXI. - Cyclometallation with N-tert-Butyl-Phosphorus-Nitrogen Iridium Complexes The interaction of R¹R²N–PNR³ ( 1 ) (R¹  SiMe₃, tBu, iC₃H₇; R²  R³  SiMe₃, tBu) with [M(COD)(μ-Cl)]₂ ( 2 ), M  Rh, Ir, affords the amino(imino)phosphane complexes 3 , whose PN bond adds methanol with formation of the diamidophosphite complexes 4 . Already below 0°C the iridium compounds of 4 undergo cyclometallation of a tBu methyl group (R²) with formation of the hydrido-iridium metallaheterocycles 5 . The structures of 4b and 5a are elucidated by X-ray analyses.     

Zur umsetzung von trimethylsilyl-methylen-dimethylsulfuran mit carbonylverbindungen : Reaktionen mit organosiliziumverbindungen, 1. mitt.

The first step in the reaction of trimethylsilylmethylene-dimethylsulfurane 1 (prepared from (CH₃)₃SiCH₂S?(CH₃)₂ī with 1 equivalent (CH₃)₃COK) with carbonyl compounds (R¹)(R²)CHCOCH₂R³2 leads Peterson-like way to the non-isolable vinylsulfoniumdimethylsilanolate-intermediate B or its recombined product A. Depending on the reaction conditions and the nature of the substituents R¹, R² and R³ there exist five different pathways to the end products 3–7. Frequently one can find an elimination of trimethylsilanole followed by a 2,3-sigmatropic rearrangement of an allyl-substituted methylene - sulfurane - intermediate to the 2,3,3 - trialkyl - 5 -thiahex -1 - enes 3 [CH₃SCH₂C(R¹)(R²)C(CH₂R³)=CH₂]. Sometimes this formation of 3 is suppressed by means of two equivalents of (CH₃)₃COK. In this case demethylation of the assumed precursor B arises yielding the E,Z-vinylsulfides 4 [CH₃SCH=C(CH₂R³)(CHR¹R²)], whereas the formation of the methylthiomethyl-dialkylcar-binoles 5 [CH₃SCH₂C(OH)(CH₂R³)(CHR¹R²)] can be explained by the demethylation of the precursor A. Treatment with five equivalents of (CH₃)₃COK yields in one case the 2,2,5,7 - tetramethyl - 5 - hydroxy - 3 - oxaoctane (7a) as

a consequence of a extrusion of dimethylsulfide. Frequently also epoxides of type 6 [CH₂-C(CH₂R³)(CHR¹R²)] can be isolated. Their formation is compared with the well-known preparation of epoxides by the dimethylsulfonium-methylide on the one and dimethylsulfoxoniummethylide on the other side.     

Selective transport of zinc and copper ions by synthetic ionophores using liquid membrane technology

This work highlights the role of synthetic carrier (ionophore) in the separation of heavy metal ions. A new series of ionophores; 4,4′-nitrophenyl-azo-O,O′-phenyl-3,6,9-trioxaundecane-1,10-dioate (R₁), bis[4,4′nitro-phenylazo-naphthyl-(2,2-dioxydiethylether)] (R₂) 1,8-bis-(2-naphthyloxy)-3,6-dioxaoctane (R₃), 1,11-bis-(2-naphthyloxy)-3,6,9-trioxaunde-cane (R₄), 1,5-bis-(2-naphthyloxy)-3-oxa-pentane (R₅) have been synthesized and used as extractant as well as carrier for the transport of various metal ions (Na⁺, K⁺, Mg²⁺, Ni²⁺, Cu²⁺ and Zn²⁺) through liquid membranes. Effect of various parameters such as metal ion concentration, ionophore concentration, liquid–liquid extraction, back extraction, comparison of transport efficiency of BLM and SLM and different membrane support (hen’s egg shell and PTFE) have been studied. In BLM ionophores (R₂–R₅) transport Zn⁺ at greater extent and the observed trend for the transport of Zn²⁺ is R₂?>?R₄?>?R₃?>?R₅ respectively. Further transport efficiency is increased in SLM. In egg shell membrane ionophores (R₂–R₅) transport Zn⁺ due to their non-cyclic structure and pseudo cavity formation while ionophore R₁ transports Cu²⁺ ions at greater extent due to its cyclic structure and cavity size. Among the membrane support used egg shell membrane is found best for the transport of zinc ions because of its hydrophobic nature and exhibits electrostatic interactions between positively charged zinc ions and –COOH group of egg shell membrane. Thus structure of ionophores, hydrophobicity and porosity of the membrane support plays important role in separation of metal ions.     

Carbon-13 n.m.r. study of 31P?13C spin–spin coupling constants in dichloro- and monochloro-vinyl phosphate derivatives

Carbon-13 chemical shifts and J(PC) coupling constants of 29 vinyl phosphate derivatives are presented. In the series of compounds (R₁O)₂P(O)OC¹(R)?C²X₂ (where 3 in R indicates the first carbon of the R₂ substituent) large differences were found between the ³J(P, O, C-1, C-3) and ³J(P, O, C-1, C-2) coupling constants of the chlorinated (X?CI) and the unsubstituted (X?H) derivatives. A possible explanation of this phenomenon is given on the basis of Jameson's s bond character theory. Strong stereospecificity of ³J(P, O, C-1, C-3) coupling constants was observed in the series of compounds (R₁O)₂ P(O)OC¹(R)?C²HR₃. Coupling constants varied between 3.2–4.9 Hz in the E isomers, while peaks could not be resolved in the Z isomers. The ³J(P, O, C-1, C-2) coupling constants were regularly 20–30% greater in the Z than in the E isomers.     

Titanium complexes bearing amine bis(phenolate) ligands: Synthesis,structure and catalysis in ring‐opening polymerization of lactide

Monomeric bis(isopropoxy) titanium complexes LTi(Oⁱ Pr)₂ (L =  ─ OC₆H₂–4‐R¹–6‐R²–2‐CH₂N[(CH₂)₂N(R³)₂]CH₂–4‐R⁴–6‐R⁵‐C₆H₂O ─ , R¹ = R² = ^t Bu, R³ = Et, R⁴ = R⁵ = Cl, (L¹)Ti(Oⁱ Pr)₂; R¹ = R² = Me, R³ = Et, R⁴ = R⁵ = Me, (L²)Ti(Oⁱ Pr)₂; R¹ = R² = ^t Bu, R³ = Et, R⁴ = OMe, R⁵ = ^t Bu, (L³)Ti(Oⁱ Pr)₂; R¹ = R⁴ = OMe, R³ = Et, R² = R⁵ = ^t Bu, (L⁴)Ti(Oⁱ Pr)₂; R¹ = R² = ^t Bu, R³ = Me, R⁴ = OMe, R⁵ = ^t Bu, (L⁵)Ti(Oⁱ Pr)₂) supported by amine bis(phenolate) ligands were synthesized and characterized using NMR spectroscopy and elemental analysis. The solid‐state structure of (L³)Ti(Oⁱ Pr)₂ was determined using single‐crystal X‐ray diffraction. (L^1–5)Ti(Oⁱ Pr)₂ were all found to initiate the ring‐opening polymerization of l ‐lactide and rac ‐lactide in a controlled manner at 110–160°C. As shown by kinetic studies, (L¹)Ti(Oⁱ Pr)₂ polymerized l ‐lactide faster than did (L^2–5)Ti(Oⁱ Pr)₂. In addition, good number‐average molecular weight and narrow polydispersity index (1.00–1.71) of polymers were also obtained. The microstructure of the polymers and a possible mechanism of coordination–insertion of polymerization were evidenced by MALDI‐TOF and ¹H NMR spectra of the polylactides.     

Quasi‐living copolymerization of ethylene with 1‐hexene by heteroligated (salicylaldiminato β‐enaminoketonato) titanium complexes

A series of heteroligated (salicylaldiminato)(β‐enaminoketonato)titanium complexes [3‐Bu^t‐2‐OC₆H₃CH = N(C₆F₅)] [PhN = C(R₁)CHC(R₂)O]TiCl₂ [ 3a : R₁ = CF₃, R₂ = ^tBu; 3b : R₁ = Me, R₂ = CF₃; 3c : R₁ = CF₃, R₂ = Ph; 3d : R₁ = CF₃, R₂ = C₆H₄Ph(p ); 3e : R₁ = CF₃, R₂ = C₆H₄Ph(o ); 3f : R = CF₃, R₂ = C₆H₄Cl(p ); 3g : R₁ = CF₃; R₂ = C₆H₃Cl₂(2,5); 3h : R₁ = CF₃, R₂ = C₆H₄Me(p )] were investigated as catalysts for ethylene (co)polymerization. In the presence of modified methylaluminoxane as a cocatalyst, these complexes showed activities about 50%–1000% and 10%–100% higher than their corresponding bis(β‐enaminoketonato) titanium complexes for ethylene homo‐ and ethylene/1‐hexene copolymerization, respectively. They produced high or moderate molecular weight copolymers with 1‐hexene incorporations about 10%–200% higher than their homoligated counterpart pentafluorinated FI‐Ti complex. Among them, complex 3b displayed the highest activity [2.06 × 10⁶ g/mol_Ti?h], affording copolymers with the highest 1‐hexene incorporations of 34.8 mol% under mild conditions. Moreover, catalyst 3h with electron‐donating group not only exhibited much higher 1‐hexene incorporations (9.0 mol% vs. 3.2 mol%) than pentafluorinated FI‐Ti complex but also generated copolymers with similar narrow molecular weight distributions (M _w/M _n = 1.20–1.26). When the 1‐hexene concentration in the feed was about 2.0 mol/L and the hexene incorporation of resultant polymer was about 9.0 mol%, a quasi‐living copolymerization behavior could be achieved. ¹H and ¹³C NMR spectroscopic analysis of their resulting copolymers demonstrated the possible copolymerization mechanism, which was related with the chain initiation, monomer insertion style, chain transfer and termination during the polymerization process. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017 , 55 , 2787–2797     

Polysulfonylamine. VII. Aliphatische Trisulfonylamine

Polysulfonyl Amines. VII. Aliphatic Trisulfonyl Amines The compounds N(SO₂R¹)₂(SO₂R²) with R¹ = R² = CH₃ ( 2a ), R¹ = R² = C₂H₅ ( 2b ) and R¹ = CH₃, R² = C₂H₅ ( 2c ) are prepared by cleavage of aminostannanes (CH₃)₃SnN(SO₂R¹)₂ with sulfonyl chlorides R²SO₂Cl. A simple synthesis of 2a from AgN(SO₂CH₃)₂ and CH₃SO₂Cl is described. From the vibrational spectra of 2a , evidence is obtained for a planar NS₃ group in this compound. X-ray structure determinations of 2b and HN(SO₂C₂H₅)₂ ( 3 ) are reported. In 2b , the NS₃ group is approximately planar (S? N? S bond angles 119.0 ± 0.6°, sum of bond angles at N 356.9°); the S? N bond lengths of ca. 173 pm indicate a bond order of 1. In compound 3 , the nitrogen atom has a planar coordination (S? N? S angle 125.3°, sum of bond angles at N 359.3°), the S? N bond lengths of ca. 165 pm correlate with a bond order of 1.3? 1.4.     

Synthesis,characterization, and biocide activity of new dithiocarbamate-based complexes of In(III), Ga(III), and Bi(III) – Part III

In this work, we describe the syntheses, characterization, and antifungal activity of [In{S₂CNR(R¹)}₃] (1), [Ga{S₂CNR(R¹)}₃] (2), [Bi{S₂CNR(R¹)}₃] (3), [In{S₂CNR(R²)}₃] (4), [Ga{S₂CNR(R²)}₃] (5), and [Bi{S₂CNR(R²)}₃] (6) {R?=?Me; R¹?=?CH₂CH(OMe)₂; and R²?=?2-methyl-1,3-dioxolane}. All complexes have been characterized using infrared and ¹H and ¹³C spectroscopy, and the structures of 1, 3, 4, and 6 have been authenticated by X-ray diffraction. The In(III)–dithiocarbamate bonding scheme depicts a distorted octahedral with asymmetric In(III)–S bonds and S–In–S angles. A pentagonal bipyramid is observed for the corresponding Bi(III) complexes with intermolecular Bi–S associations through the lone pair of electrons. The antifungal activities of 1–6 have been screened against Aspergillus niger, Aspergillus parasiticus, and Penicillium citrinum, and the results have been compared with those of nystatin and miconazole nitrate, as control drugs.     

Unprecedented Reaction Pathway of Sterically Crowded Calcium Complexes: Sequential C−N Bond Cleavage Reactions Induced by C−H Bond Activations

Five bis(quinolylmethyl)‐(1H ‐indolylmethyl)amine (BQIA) compounds, that is, {(quinol‐8‐yl‐CH₂)₂NCH₂(3‐Br‐1H ‐indol‐2‐yl)} ( L¹H ) and {[(8‐R³‐quinol‐2‐yl)CH₂]₂NCH(R²)[3‐R¹‐1H ‐indol‐2‐yl]} ( L^2–5H ) ( L²H : R¹=Br, R²=H, R³=H; L³H : R¹=Br, R²=H, R³=i Pr; L⁴H : R¹=H, R²=CH₃, R³=i Pr; L⁵H : R¹=H, R²=n Bu, R³=i Pr) were synthesized and used to prepare calcium complexes. The reactions of L^1–5H with silylamido calcium precursors (Ca[N(SiMe₂R)₂]₂(THF)₂, R=Me or H) at room temperature gave heteroleptic products ( L^{1, 2} )CaN(SiMe₃)₂ ( 1 , 2 ), ( L^{3, 4} )CaN(SiHMe₂)₂ ( 3 a , 4 a ) and homoleptic complexes ( L^{3, 5} )₂Ca ( D3 , D5 ). NMR and X‐ray analyses proved that these calcium complexes were stabilized through Ca⋅⋅⋅C−Si, Ca⋅⋅⋅H−Si or Ca⋅⋅⋅H−C agostic interactions. Unexpectedly, calcium complexes (( L^3–5 )CaN(SiMe₃)₂) bearing more sterically encumbered ligands of the same type were extremely unstable and underwent C−N bond cleavage processes as a consequence of intramolecular C−H bond activation, leading to the exclusive formation of (E )‐1,2‐bis(8‐isopropylquinol‐2‐yl)ethane.     

Binukleare Nickel(II)‐Komplexe mit Oxalamidinaten als Brückenliganden: Synthese und Strukturen von Verbindungen mit planarer,tetraedrischer, tetragonal‐pyramidaler und oktaedrischer Koordination

Binuclear Nickel(II) Complexes with Oxalamidinates as Bridging Ligands: Synthesis and Struktures of Compounds with Planar, Tetrahedral, Tetragonal‐pyramidal, and Octahedral Coordination Oxalamidines R¹–NH–C(=NR²–C(=NR²)–NH–R¹ react selectively with Ni(acac)₂ under formation of the planar complexes [(acac)Ni(oxalamidinate)Ni(acac)]. Two crystal structures of the binuclear complexes with R = R′ = Ph ( 1 ) or p‐tolyl ( 2 ) show that the bridging oxalamidinates bind as bidendate ligands at each Nickel(II) atom. In contrast, the more sterically demanding fragment (Ph₃P)NiBr can only coordinate at sterically less demanding oxalamidinates to form complexes of the type [(Ph₃P)NiBr]₂(oxalamidinate) with tetrahedral coordination of Ni^II found by X‐ray analyses. Oxalamidines containing additional donor atoms in the side arms react very different, but in each case under formation of binuclear complexes, such as [(acac)₂Ni]₂( H₂E ) ( 8 ) (with R¹: –(CH₂)₃PPh₂, R²: p‐tolyl) in which the oxalamidine acts as bidentate neutral P,N‐ligand and the Ni^II atom has an octahedral environment. H₂F (with R¹: –(CH₂)₃PPh₂, R²: Mesityl), however, yields the planar complex [(acac)Ni]₂( F ) ( 9 ) with dianionic oxalamidinate under elimination of acetylacetone. There is no coordination of the donor groups of the side arms in the solid state of complex 9 , in contrast to the analogous binuclear complex [(acac)Ni]₂( H ) 10 (R¹: –CH₂–CH₂‐2‐pyridyl, R²: Mesityl). In this complex a distorted tetragonal‐pyramidal coordination of Ni^II is achieved. 2 reacts with an excess of LiCH₃ under elimination of the oxalamidinate to form the cluster compound Li₄(THF)₄Ni₂Me₈ in very good yields, while 9 yields the THF poorer cluster Li₂(THF)₂Li₂Ni₂Me₈ under similar conditions.     

Dissociation constants of 2‐azidoethanamines in aqueous solution

Aqueous‐phase dissociation constants (K_a) for the conjugate acids of a series of 2‐azidoethanamine bases: R¹N(R²)CH₂CH₂N₃ ( 1 , R¹ = CH₃, R² = H; 2 , R¹ = CH₃, R² = CH₃; 3 , R¹ = CH₂CH₃, R² = CH₂CH₃; 4 , R¹/R² =  CH₂CH₂CH₂CH₂ ; 5 , R¹/R² =  CH₂CH₂OCH₂CH₂ ; 6 , R¹ = CH₂CH₃, R² = CH₂CH₂N₃) were measured and found to fall between those for analogous unfunctionalized and cyano‐functionalized ethanamines. To explore the possibility of a relationship existing between the constants and molecular geometry, a theoretically based study was conducted. In it, the Gibbs free energies of aqueous‐phase (equilibrium) conformers of the bases and their conjugate acids were determined via a density functional theory/polarizable continuum model method. The results indicate that an attractive interaction between the amine and azide groups that underlies the lowest‐energy gas‐phase conformer of 2 is negated in an aqueous environment by solvent–solute interactions. The magnitudes of the free energy changes of solvation and −TS (entropic) energies of the conformers of the 2‐azidoethanamines and their conjugate acids are observed to correlate with the magnitude of the separation between the conformers' amine and azide groups. However, those correlations are not by themselves sufficient to predict the relative free energies of a molecule's conformers in an aqueous environment. That insufficiency is due to the influence of the correlations being mitigated by three other parameters that arise within the thermodynamic framework employed to compute the observable. The nature of those parameters is discussed. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010