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The Pd‐catalysed decarboxylative asymmetric allylic alkylation (DAAA) has been applied to the enantioselective synthesis of sterically hindered benzofuran‐3(2H)‐one‐derived α‐aryl‐β‐keto esters employing the (R,R)‐ANDEN phenyl Trost ligand. A range of substrates were synthesised, employing previously developed aryllead triacetate methodology to install various aryl groups. The resulting α‐aryl‐α‐allyl benzofuran‐3(2H)‐one DAAA products were obtained in moderate to high yields and in enantioselectivities of up to 96 % ee, with the best results observed for substrates containing a di‐ortho‐substitution pattern on the aryl ring as well as naphthyl‐containing substrates. [ABSTRACT FROM AUTHOR]

Three new methoxide-bridged Cu(II) dimers are reported: tetrakis(2-methylpyrazine)di(μ-methoxy)diperchloratodicopper(II) (1), tetrakis(2-amino-5-iodopyridine)dibromide-di-μ-methoxydicopper(II) tetramethanol (2) and catena[(2-amino-5-methylpyridine)μ-bromido-μ-methoxycopper(II) (3). The compounds were characterized by single-crystal X-ray diffraction and variable temperature magnetic measurements. All three compounds crystallize in the triclinic space group P-1, and the dimers lie across a crystallographic inversion center. The dimers in 3 are further bridged into an alternating chain motif via semi-coordinated Cu(II)/Br interactions. All three compounds exhibit strong antiferromagnetic interactions with J/kB = −348(8) K for 1, and the exchange in 2 and 3 being too strong to estimate from the available data. The magnetic data for 1-3 are dominated by trace paramagnetic impurities at temperatures below 200 K. Correlation of the structures with the observed magnetic behavior is proposed. [ABSTRACT FROM AUTHOR]

Pyrido-phenanthrolin-7-one compounds are structural analogues of the cytotoxic alkaloid, ascididemin, and would be expected to have interesting biological activities. Synthetic strategies are reported for a novel simple route to form this class of ligand. 1,10-Phenanthrolin-5,6-dione reacts with L -phenylalanine alkyl esters and their para-substituted analogues to form both a phenanthroline–oxazine and a pyrido-phenanthrolin-7-one product. The nature of the major product is dependent on the electronic properties of the para substituent. Successful metal coordination to the pyrido-phenanthrolin-7-one ligand is also presented. [ABSTRACT FROM AUTHOR]

Abstract: High‐valent Ni oxidants have been implicated in hydrocarbon oxidation catalysis, however, little is understood about the properties of these oxidants. Herein, a family of NiII complexes supported by a pyridinedicarboxamidate ligand and different ancillary ligands was synthesized. The series spans coordination numbers 4, 5, and 6, and contains neutral, mono‐ and di‐anionic donor types. X‐ray crystallography and magnetic measurements showed that the 4‐coordinate complexes were square planar and low spin (S=0) and the 5‐ and 6‐coordinate were intermediate spin (S=1). The NiII complexes could be oxidized by one electron to form a series of metastable NiIII species. EPR analysis confirmed their description as S= 1 / 2 NiIII compounds with signal shape and hyperfine coupling dependent on the coordination environment. The oxidation of phenols by the NiIII species was probed, providing evidence for a correlation between oxidizing power and electron‐donating properties of the supporting ligands. Critically, we found that the pyridinedicarboxamidate ligand may be a non‐innocent proton acceptor in the oxidation reactions. [ABSTRACT FROM AUTHOR]

A series of 10-[(4-halo-2,6-diisopropylphenyl)imino]- phenanthren-9-ones and derivatives of the phenanthrene-9,10- dione ligand have been synthesised and structurally characterised to explore two types of noncovalent interactions, namely the influence of the steric bulk upon the resulting C-H···π and π-stacking interactions and halogen bonding. Selected noncovalent interactions have additionally been analysed by DFT and AIM techniques. No halogen bonding has been observed in these systems, but X lone pair···π, C-H···O=C and C-H···π interactions are the prevalent ones in the halogenated systems. Removal of the steric bulk in N-(2,4,6-trimethylphenyl)-9,10-iminophenanthrenequinone affords different noncovalent interactions, but the C-H···O=C hydrogen bonds are observed. Surprisingly, in N-(2,6-dimethylphenyl)-9,10-iminophenanthrenequinone and N-(phenyl)-9,10-iminophenanthrenequinone these C-H···O=C hydrogen bonds are not observed. However, they are observed in the related 2,6-di-tert-butylphenanthrene-9,10- dione. The π-interactions in dimers extracted from the crystal structures have been analysed by DFT and AIM. Spectroscopic investigations are also presented and these show only small perturbations to the O=C-C=N fragment. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Chemistry is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Comproportionation reactions between MnCl2 and KMnO4 in the presence of arsonate or phosphonate ligands promote the cation-assisted assembly of high-nuclearity, wheel-shaped or toroidal {Mn8} (1) and {Mn24} (2) complexes; the closely corresponding reaction systems provide insights into the complexation behaviour of homologous phosphonate/arsonate ligand species. [ABSTRACT FROM AUTHOR]

The synthesis of five new 2,6-bis(1,2,3-triazol-4-yl)pyridine (btp) ligands is described: the self-assembly behaviour of the tri-methyl ester, 1, with Eu(iii) showed the formation of a luminescent 1 : 3 Eu : btp complex, Eu13, which was studied in solution and in the solid state; while the tri-carboxylic acid, 2, formed a hydrogel and its corresponding complex Eu23, gave rise to a strongly red luminescent healable metallogel. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Chemistry is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Fluorine-containing ligands 2,3,5,6-tetrafluoro-1,4-bis(imidazol-1-yl-methyl)benzene (1) and 2,3,5,6-tetrafluoro-1,4-bis(2-methylimidazol-1-yl-methyl)benzene (2) were prepared and coordinated with AgNO3, Co(ClO4)2·6H2O, and Cd(NO3)2·4H2O, respectively, to form the following structures: 3D channel polymer [Ag2(1)2(NO3)2·H2O·MeOH]n (3), 2D sheet polymer [Co(1)3(ClO4)2]n (4), 1D chain polymer [Cd(1)3(NO3)2·4H2O]n (5), and a 2D herringbone sheet polymer [Ag(2)NO3·1.5MeOH]n (6). The solid-state crystal structures of 3–6 were studied by single-crystal X-ray crystallography. [ABSTRACT FROM AUTHOR]

Two types of polymeric copper(II) complexes, [Cu(trifac)2(4-tfmpda)]2 (1), and [Cu2(hfa)4(4-tfmpda)] (2) were obtained from the reaction of bis(fluorinated-acetylacetonato)copper(II) complexes with 4-(trifluoromethyl)-1,2-phenylenediamine[4-tfmpda] in methylene chloride. 1 crystallizes in the monoclinic space group P2(1)/c, with a=7.840(2) A˚, b=11.659(3) A˚, c=22.843(6) A˚, V=2075.1(9) A˚3, and Z=2 with R=0.0474. 2 crystallizes in the triclinic space group P1¯, with a=11.644(3) A˚, b=12.599(4) A˚, c=15.171(4) A˚, V=1924.5(10) A˚3, and Z=2 with R=0.0686. 1 exists as a 1-D infinite polymeric chain where 4-tfmpda is linked by weak coordination bonds around two copper(II) centers, while 2 is a 1-D polymer formed by hydrogen bonds and very weak Cu⋯Cu interactions. [Copyright &y& Elsevier]

Demonstrates the synthesis of a homologous series of heavier element dipnictenes 2,6Ar2H3C6E=EC6H3-2,6-Ar2, where E= P, As, Sb, Bi. Stabilization of the double-bonded dipnictenes by meta-terphenyl ligands; Structural characterization of the compounds by H and C nuclear magnetic resonance spectroscopy.

Development of new ligands for fac-M(OH2)3(CO)3+ (M = Re, 99mTc) led the investigation with S-(pyridin-2-ylmethyl)- L-cysteine, 1. The ligand 1 has potential to coordinate with the metal through three different tridentate modes: tripodal through cysteine (O,N,S) and two linear involving the S-pyridyl and cysteine (O,S,Npy, N,S,Npy). From the reaction with 1, two species were observed in the 1H NMR, where the primary product was the linear fac-Re(N,S, Npy-1)(CO)3, 2a, complex. To identity the coordination mode of the minor product, functionalized analogues of 1 were prepared from S-(pyridln-2-ylmethyl)-Boc-L-cysteine-methyl ester, 3, with orthogonal protecting groups on the C terminus (methyl ester) in S-(pyridin-2-ylmethyl)-L-cysteine methyl ester, 4, or N terminus (Boc) in S-(pyridin2-ylmethyl)-Boc-L-cysteine, 6, that specifically directed the coordination mode of fac-M(H20)3(CO)3+ to either N,S, Npy or O,S,Npy, respectively. Two diastereomers [fac-Re(CO)3(N,S,Npy-4)]+, 5a and 5b, were observed and independently characterized by X-ray structure analysis and NMR in high yield with 4. Surprisingly, the O,S,Npy Re complex with ligand 6 was not observed and simplified versions, 3-(pyridin-2-ylmethylthio) propanoic acid, 7, and 2-(pyridin-2-ylmethylthio)acetic acid, 8, were investigated. Ligand 7 did not yield the desired linear tridentate O,S,Npy product. However, the shorter ligand 8 formed fac-Re(CO)3(O,S,Npy-8), 9, in high yield. 99mTc labeling studies were conducted and yielded similar results to the rhenium complex and effective (>99%) at 10-5 M ligand concentration. [ABSTRACT FROM AUTHOR]

Abstract: Cu(OTf)2(2-mepyz)2(H2O)2 (2-mepyz=2-methylpyrazine; OTf− = =triflate), 1, and Cu(OTf)2(H2O)2(pyz) (pyz=pyrazine), 2, consist of monomeric and polymeric structures, respectively. Both compounds contain octahedral Cu(II) metal centers surrounded by trans-coordinated OTf−, H2O, and diazines, either 2-mepyz in the case of 1 or pyz in 2. In 1, O–H⋯O(triflate) hydrogen bonds link CuO4N2 monomers into quasi-1D chains which are joined via O–H⋯N interactions to afford a three-dimensional (3D) network. Pyz ligands in 2 link CuO4N2 octahedra into linear chains similar to Cu(NO3)2(pyz). Magnetically, neither 1 or 2 show indications for long-range magnetic ordering (LRO) above 2K. Least-squares fits of the magnetic susceptibility data, χ(T), to a Bonner–Fisher uniform chain model gave 2J/k B =−0.005(1) and −6.0(1)K for compounds 1 and 2, respectively, indicative of negligible and moderate antiferromagnetic coupling between spin-1/2 Cu(II) ions. Inter-chain magnetic interactions seem to be negligible for both systems. [Copyright &y& Elsevier]

Graphical abstract Several metal complexes of a benzimidazole Schiff base were prepared and characterised showing moderate DNA binding as intercalators and interesting activity against Gram positive and negative bacteria. Abstract The benzimidazole derivative (E)-2-((4-(1 H -benzo[ d ]imidazol-2-yl)phenylimino)methyl)-4-bromo phenol and the corresponding Zn(II), Ni(II), Cu(II), and Pd(II) complexes were prepared. The synthesized ligand and complexes were fully characterized and the ligand structure confirmed by single crystal X-ray diffraction analysis. The ability of this compound and its complexes to bind to DNA was first investigated with DNA thermal denaturation experiments, in general showing weak interactions. Additionally, UV–Vis absorption spectroscopy was used to assess the binding to DNA and the corresponding binding constants (K b) were calculated suggesting an intercalative mode of binding for the benzimidazole ligand. All compounds were screened for their antibacterial activity and the Ni(II) complex showed promising results against all bacterial strains (Gram positive and Gram negative) while the rest of the compounds showed activity against selective strains. [ABSTRACT FROM AUTHOR]

A series of lanthanide complexes, {[CpCo(P=O(OR)₂)₃]₂Ln(H₂O)x}⁺Cl⁻ (Ln = Nd, 3; Eu, 4; Tb, 5; Yb, 6; R = Et, a; R = Ph, b) bearing two cobalt metalloligands were prepared. Electrospray mass spectrometry and thermogravimetric analysis suggest that the cations are either solvent-free or contain very weakly bound water molecules. The related complex {[CpCo(P=O(OPh)₂)₃]₂Yb}⁺ [CoCl₃(THF)]⁻, 7, was crystallographically characterized, and the cation in this case was confirmed to be 6-coordinate and solvent-free. Ligand exchange rates between the d0- and d60-isotopomers of 3a--6a and 5b were determined in acetonitrile by electrospray mass spectrometry. The ligand exchange rate was found to increase by almost 4 orders of magnitude from the smallest (Yb, 6a, k = 0.3 M-1 s-1) to largest ion (Nd, 3a, >2500 M-1 s-1) in acetonitrile. Additionally, the ligand exchange rate increased rapidly for 5a (Tb) with increasing water concentration from 30 M-1 s-1 in pure acetonitrile to 268 s-1 in 50:50 (v/v) acetonitrile/water. Changing the phosphite substituent had no significant impact on the rate of ligand exchange for 5b (R = Ph) relative to 5a (R = Et). [ABSTRACT FROM AUTHOR]

Abstract: The fac-Re(OH2)3(CO)3 + moiety was investigated with a known bidentate ligand, acetylactone (acac) and amine based ligands in a 2+1 and tridentate approach. In the 2+1 approach, the fac-Re(CO)3(acac)(OH2) was reacted with ethylamine to yield the monomer version fac-Re(CO)3(acac)(NH2Et), 1. Based on the Schiff base condensation of a ketone and a primary amine, a tridentate ligand approach for fac-Re(OH2)3(CO)3 + utilizing the reactivity of acac and diamine ligands (1,2 ethylene, 1,3 propylene, 1,4 butylene) was explored in a didactic manner: 1) an in situ ligand synthesis approach reacting fac-Re(CO)3(acac)(OH2) with the diamine (2+2=3) or 2) direct complexation of fac-Re(OH2)3(CO)3 + with the prepared ligand. The results observed with rhenium complexes were characterized by standard chemical analysis and X-ray analysis. [Copyright &y& Elsevier]

Abstract: The (M=Re, 99mTc) moiety was investigated with a known bidentate ligand, acetylacetone (acac) and imidazole based ligands in a 2+1 and tridentate approach. In the 2+1 approach, the fac-Re(CO)3(acac)(OH2) was reacted with imidazole or 1-methylimidazole to yield a unique anionic μ-bridging imidazol-1-ide dimer fac-[(imidazol-1-ide)-bis-(fac-acetylacetonatotricarbonylrhenium (I)], 1, or the monomer version fac-M(CO)3(acac)(1-methylimidazole), 2, respectively. Based on the Schiff base condensation of a ketone and a primary amine, a tridentate ligand approach for utilizing the reactivity of acac and histamine was explored in a didactic manner: (1) an in situ ligand synthesis approach reacting fac-M(CO)3(acac)(OH2) with histamine (2+2=3) that led to the formation of an unexpected dimer μ-acachistimine, compound, 3, or (2) direct complexation of with the prepared ligand acachistimine, 4, to yield the monomer product fac-M(CO)3(acachistimine), 5. The results observed with rhenium complexes characterized by standard chemical analysis and X-ray analysis correlated with the radioactive experiments conducted with . [ABSTRACT FROM AUTHOR]

The mixed-ligand complex [Ni(dppp)(PPh2NBz2)](BF4)2, 3, (where PPh2NBz2 is 1,5-dibenzyl-3,7- diphenyl-1,5-diaza-3,7-diphosphacyclooctane and dppp is 1,3-bis(diphenylphosphino)propane) has been synthesized. Treatment of this complex with H2 and triethylamine results in the formation of the Ni0 complex, Ni(dppp)(PPh2NBz2), 4, whose structure has been determined by a single-crystal X-ray diffraction study. Heterolytic cleavage of H2 by 3 at room temperature forms [HNi(dppp)(PPh2NBz(μ-H)NBz](BF4)2, 5a, in which one proton interacts with two nitrogen atoms of the cyclic diphosphine ligand and a hydride ligand is bound to nickel. Two intermediates are observed for this reaction using low-temperature NMR spectroscopy. One species is a dihydride, [(H)2Ni(dppp)(PPh2NBz2)](BF4)2, 5b, and the other is [Ni(dppp)(PPh2NBz2H2)](BF4)2, 5c, in which both protons are bound to the N atoms in an endo geometry with respect to nickel. These two species interconvert via a rapid and reversible intramolecular proton exchange between nickel and the nitrogen atoms of the diphosphine ligand. Complex 3 is a catalyst for the electrochemical oxidation of H2 in the presence of base, and new insights into the mechanism derived from low-temperature NMR and thermodynamic studies are presented. A comparison of the rate and thermodynamics of H2 addition for this complex to related catalysts studied previously indicates that for NiII complexes containing two diphosphine ligands, the activation of H2 is favored by the presence of two positioned pendant bases. [ABSTRACT FROM AUTHOR]

Reaction of [NEt4]2[ReBr3(CO)3] with 24-pentanedione (acac) yields a complex of the type fac-Re(acac)(0H2)(CO)3 (1) under aqueous conditions. 1 was further reacted with a monodentate ligand (pyridine) to yield a fac-Re(acac)(pyridine)(CO)3 complex (2). Complex 1 was found to react with primary amines to generate a Schiff base (imine) in aqueous solutions. When a mixed-nitrogen donor bidentate ligand, 2-(2-aminoethyl)pyridine, that has different coordination affinities for fac-Re(acac)(0H2)(CO)3 was utilized, a unique tridentate ligand was formed in situ utilizing a metal-assisted Schiff base formation to yield a complex fac-Re(CO)3(3[(2- phenylethyl)imino]-2-pentanone) (3). Tridentate ligand formation was found to occur only with the Re-coordinated acac ligand. Reactions of acac with fac-Re(CO)3Br(2-(2-aminoethyl)pyridine) (4) or a mixture of [NEt4]2[ReBr3(CO)3], acac, and 2-(2-aminoethyl)pyridine did not yield the formation of complex 3 in water; [ABSTRACT FROM AUTHOR]

Using a mixed-ligand synthetic scheme, we create a family of quasi-two-dimensional antiferromagnets, namely, [Cu(HF2)(pyz)2]ClO4 [pyz = pyrazine], [CuL2(pyz)2](ClO4)2 [L = pyO = pyridine-N-oxide and 4-phpy-O = 4-phenylpyridine-N-oxide. These materials are shown to possess equivalent two-dimensional [Cu(pyz)2]2+ nearly square layers, but exhibit interlayer spacings that vary from 6.5713 to 16.777 Å, as dictated by the axial ligands. We present the structural and magnetic properties of this family as determined via x-ray diffraction, electron-spin resonance, pulsed- and quasistatic-field magnetometry and muon-spin rotation, and compare them to those of the prototypical two-dimensional magnetic polymer Cu(pyz)2(ClO4)2. We find that, within the limits of the experimental error, the two-dimensional, intralayer exchange coupling in our family of materials remains largely unaffected by the axial ligand substitution, while the observed magnetic ordering temperature (1.91 K for the material with the HF2 axial ligand, 1.70 K for the pyO and 1.63 K for the 4-phpy-O) decreases slowly with increasing layer separation. Despite the structural motifs common to this family and Cu(pyz)2(ClO4)2, the latter has significantly stronger two-dimensional exchange interactions and hence a higher ordering temperature. We discuss these results, as well as the mechanisms that might drive the long-range order in these materials, in terms of departures from the ideal S=1/2 two-dimensional square-lattice Heisenberg antiferromagnet. In particular, we find that both spin-exchange anisotropy in the intralayer interaction and interlayer couplings (exchange, dipolar, or both) are needed to account for the observed ordering temperatures, with the intralayer anisotropy becoming more important as the layers are pulled further apart. [ABSTRACT FROM AUTHOR]