The preparation of 4-oxo-N-aryl-4H-1-benzopyran-2-acetamides by the condensation/cyclization of trilithiated acetoacetanilides with lithiated methyl salicylates

Several acetoacetanilides were trilithiated in excess lithium diisopropylamide, and the resulting polylithiated intermediates were regioselectively condensed with lithiated methyl salicylates followed by acid cyclization to substituted 4-oxo-N-aryl-4H-1-benzopyran-2-acetamides (benzopyranone-2-acetamides).     

Synthesis and Characterization of a New Quasi-One-Dimensional Copper(II) Phosphate, Ba(2)Cu(PO(4))(2)

Crystals of Ba(2)Cu(PO(4))(2) have been grown in a low-temperature eutectic flux of 32% KCl and 68% CuCl (mp = 140 degrees C). The X-ray single-crystal structure analysis shows that this barium copper(II) phosphate crystallizes in a monoclinic lattice with a = 12.160(4) ?, b = 5.133(4) ?, c = 6.885(4) ?, beta = 105.42(4) degrees, and V = 414.3(4) ?(3); C2/m (No. 12); Z = 2. The structure has been refined by the least-squares method to a final solution with R = 0.020, R(w) = 0.026, and GOF = 1.05. The framework of the title compound consists of [Cu(PO(4))(2)](infinity) linear chains with Ba(2+) cations residing between these parallel chains. The chains are composed of an array of Cu(2+) cations that are doubly bridged by PO(4) anions. Each pair of bridging PO(4) tetrahedra are in a staggered configuration above and below the CuO(4) square plane, resulting in a linear chain with a long Cu---Cu separation distance, 5.13 ? ( identical withb). This quasi-one-dimensional framework is unusual among the Cu(2+)-based phosphates. Magnetic susceptibility data shows Curie-Weiss paramagnetic behavior in the range of ca. 190-300 K and a possible antiferro-to-ferromagnetic transition at approximately 8 K. In this paper, the synthesis, structure, and properties of the title compound are presented. A structural comparison to a closely related vanadyl (VO)(2+) phosphate, Ba(2)(VO)(PO(4))(2).H(2)O, as well as Na(2)CuP(2)O(7) will be discussed.     

Comparative properties of siloxane vs phosphonate monolayers on a key titanium alloy

A direct comparison of surface loading, interface shear strength, and interface hydrolytic stability was made between a phosphonate and two siloxane monolayers formed on the native oxide surface of Ti-6Al-4V. Surface loading for the phosphonate was ca. four times greater (on a nanomole/area basis) than for the siloxanes; mechanical strengths per surface-bound molecule were comparable, but the hydrolytic stability (pH 7.5) of the siloxanes was poor. These results suggest that phosphonate monolayer interfaces are more desirable than comparable siloxane ones for applications where such interfaces contact even slightly alkaline water.     

Free radical-mediated vinyl amination: access to N,N-dialkyl enamines and their beta-stannyl and beta-thio derivatives

[reaction: see text] The first examples of free radical-mediated vinyl amination are described by nonconventional vinyl radical addition to azomethine nitrogen. This new vinyl amination protocol is mild and provides convenient synthetic access to nonstabilized N,N-dialkyl enamines and tandem bond-forming processes.     

New approach to Ru(II) pincer ligand chemistry. Bis(tert-butylaminomethyl)pyridine coordinated to ruthenium(II)

Reaction of 2,6-bis-(tBuNHCH2)2NC5H3 ("N2py") with RuCl2(PPh3)3 gives two isomers of Ru(N2py)Cl2(PPh3), 5, while reaction with RuCl2(DMSO)4 (DMSO = Me2SO) gives isomerically pure Ru(N2py)Cl2(DMSO), whose structure is reported. The PPh3 of 5 can be replaced by CO, P(OPh)3, or pyridine. The chlorides in Ru(N2py)Cl2(CO) can both be replaced by F3CSO3-. Isomer structure preferences are discussed, and the reaction of Ru(N2py)Cl2(pyridine) with O2 gives apparent oxidation of N2py to give the diimine.     

Na(4)Mn(0.5)P(0.5)O(5): Synthesis of a Novel Mixed-Metal Manganese(VII)/Phosphorus(V) Oxide via Hydroxide Flux

Vibrant blue crystals of Na(4)Mn(0.5)P(0.5)O(5) were synthesized via a sodium hydroxide flux. The X-ray structural analysis showed that this sodium manganese(VII) phosphorous oxide crystallizes in an orthorhombic lattice with a = 8.967(3) ?, b = 7.291(3) ?, c = 8.090(3) ?: Pnma (No. 62); Z = 4. The manganese and phosphorus cations equally share one crystallographic site and are tetrahedrally coordinated. The (Mn,P)O(4) tetrahedra are held together by sodium cations via Na-O bonds forming an ionic solid, [Na(4)O](2+)[(Mn(0.5)P(0.5))O(4)](2)(-). The synthesis, structure, thermal property and infrared spectroscopy of the title compound are presented in this paper.     

Decarbonylative ether dissection by iridium pincer complexes

A unique chain-rupturing transformation that converts an ether functionality into two hydrocarbyl units and carbon monoxide is reported, mediated by iridium(i) complexes supported by aminophenylphosphinite (NCOP) pincer ligands. The decarbonylation, which involves the cleavage of one C–C bond, one C–O bond, and two C–H bonds, along with formation of two new C–H bonds, was serendipitously discovered upon dehydrochlorination of an iridium(iii) complex containing an aza-18-crown-6 ether macrocycle. Intramolecular cleavage of macrocyclic and acyclic ethers was also found in analogous complexes featuring aza-15-crown-5 ether or bis(2-methoxyethyl)amino groups. Intermolecular decarbonylation of cyclic and linear ethers was observed when diethylaminophenylphosphinite iridium(i) dinitrogen or norbornene complexes were employed. Mechanistic studies reveal the nature of key intermediates along a pathway involving initial iridium(i)-mediated double C–H bond activation.

A unique chain-rupturing transformation that converts an ether functionality into two hydrocarbyl units and carbon monoxide is reported.     

Morphology of adsorbed polymers and solid surface wettability

The adsorption of a polyacrylamide (MW 14600) and two polysaccharides (MW 9260 and 706 x 10(3)) onto model silica surfaces of different hydrophobicities was investigated. In all cases, adsorption adhered to the Freundlich isotherm, reflecting the heterogeneous character of the solid substrates. The latter strongly influenced the character of the adsorbed polymer, with morphologies from chainlike structures to thin films and patches being observed. Surface roughness, polymer type, and molecular weight also play roles in controlling adsorbed polymer morphology. Surface wettability is strongly influenced by the thickness of the adsorbed layer.     

Single-molecule magnets: novel Mn(8) and Mn(9) carboxylate clusters containing an unusual pentadentate ligand derived from pyridine-2,6-dimethanol

The reactions of the Mn(III)(3) and Mn(II)Mn(III)(2) complexes [Mn(3)O(O(2)CEt)(6)(py)(3)][ClO(4)] and [Mn(3)O(O(2)CEt)(6)(py)(3)] with pyridine-2,6-dimethanol (pdmH(2)) afford the mixed-valence Mn(II)(6)Mn(III)(2) octanuclear complex [Mn(8)O(2)(py)(4)(O(2)CEt)(8)(L)(2)][ClO(4)](2) (1) and the Mn(II)(7)Mn(III)(2) enneanuclear complex [Mn(9)(O(2)CEt)(12)(pdm)(pdmH)(2)(L)(2)] (2), respectively. Both compounds contain a novel pentadentate ligand, the dianion of (6-hydroxymethylpyridin-2-yl)-(6-hydroxymethylpyridin-2-ylmethoxy)methanol (LH(2)), which is the hemiacetal formed in situ from the Mn-assisted oxidation of pdmH(2). Complex 1 crystallizes in the monoclinic space group P2(1)/n with the following cell parameters at -160 degrees C: a = 16.6942(5) A, b = 13.8473(4) A, c = 20.0766(6) A, beta = 99.880(1) degrees, V = 4572.27 A(3), and Z = 2, R (R(w)) = 4.78 (5.25). Complex 2.0.2MeCN crystallizes in the triclinic space group Ponemacr; with the following cell parameters at -157 degrees C: a = 12.1312(4) A, b = 18.8481(6) A, c = 23.2600(7) A, alpha = 78.6887(8) degrees, beta = 77.9596(8) degrees, gamma = 82.3176(8) degrees, V = 5076.45 A(3), and Z = 2, R (R(w)) = 4.12 (4.03). Both complexes are new structural types comprising distorted-cubane units linked together, albeit in two very different ways. In addition, complex 2 features three distinct binding modes for the chelating ligands derived from deprotonated pdmH(2). Complexes 1 and 2 were characterized by variable-temperature ac and dc magnetic susceptibility measurements and found to possess spin ground states of 0 and 11/2, respectively. Least-squares fitting of the reduced magnetization data gave S = 11/2, g = 2.0, and D = -0.11 cm(-1) for complex 2, where D is the axial zero-field splitting parameter. Direct current magnetization versus field studies on 2 at <1 K show hysteresis behavior at <0.3 K, establishing 2 as a new single-molecule magnet. Magnetization decay measurements gave an effective barrier to magnetization relaxation of U(eff) = 3.1 cm(-1) = 4.5 K.