catena‐Poly[[copper(II)‐μ‐2‐[bis­(2‐pyridylmeth­yl)amino]butyrato‐κ4N,N′,N′′,O:κO′] perchlorate]

The copper(II) ion in the syn–anti carboxyl­ate‐bridged one‐dimensional zigzag chain title complex, {[Cu(C₁₆H₁₈N₃O₂)]ClO₄}_n, exhibits a distorted trigonal–bipyramidal environment. Two N atoms and one carboxyl­ate O atom of the ligand form the basal plane, while the axial positions are filled by an N atom of the ligand and one O atom belonging to the carboxyl­ate group of an adjacent mol­ecule. The crystal packing is enhanced by C—H⋯O(perchlorate) hydrogen bonds.     

Critical factors for high-performance physically adsorbed (dynamic) polymeric wall coatings for capillary electrophoresis of DNA

Physically adsorbed (dynamic) polymeric wall coatings for microchannel electrophoresis have distinct advantages over covalently linked coatings. In order to determine the critical factors that control the formation of dynamic wall coatings, we have created a set of model polymers and copolymers based on N,N-dimethylacrylamide (DMA) and N,N-diethylacrylamide (DEA), and studied their adsorption behavior from aqueous solution as well as their performance for microchannel electrophoresis of DNA. This study is revealing in terms of the polymer properties that help create an "ideal" wall coating. Our measurements indicate that the chemical nature of the coating polymer strongly impacts its electroosmotic flow (EOF) suppression capabilities. Additionally, we find that a critical polymer chain length is required for polymers of this type to perform effectively as microchannel wall coatings. The effective mobilities of double-stranded (dsDNA) fragments within dynamically coated capillaries were determined in order to correlate polymer hydrophobicity with separation performance. Even for dsDNA, which is not expected to be a strongly adsorbing analyte, wall coating hydrophobicity has a deleterious influence on separation performance.     

Bonding and redox properties of [Os(3)(CO)(9)(tmbp)(L)] (tmbp=4,4',5,5'-tetramethyl-2,2'-biphosphinine; L=CO, PPh(3)) clusters with an unprecedented electron-deficient metallic core and doubly bridging biphosphinine dianion

Herein we describe in detail the bonding properties and electrochemical behavior of the first known triosmium carbonyl clusters with a coordinated redox-active ligand 4,4',5,5'-tetramethyl-2,2'-biphosphinine (tmbp), the phosphorus derivative of 2,2'-bipyridine. The clusters investigated were [Os(3)(CO)(10)(tmbp)] (1) and its derivative [Os(3)(CO)(9)(PPh(3))(tmbp)] (2). The crystal structures of both clusters are compared with those of relevant compounds; they served as the basis for density functional theory (DFT and time-dependent DFT) calculations. The experimental and theoretical data reveal an unexpected and unprecedented bridging coordination mode of tmbp, with each P atom bridging two metal atoms. The tmbp ligand is formally reduced by transfer of two electrons from the triangular cluster core that consequently lacks one of the metal-metal bonds. Both 1 and 2 therefore represent 50e(-) clusters with a coordinated 8e(-) donor, [tmbp](2-). The HOMO and LUMO of 1 and 2 possess a predominant contribution from different pi*(tmbp) orbitals, implying that the lowest energy excited state possesses a significant intraligand character. This is in agreement with the photostability of these clusters. DFT calculations also predict the experimentally observed structure of 1 to be the most stable one in a series of several plausible structural isomers. Stepwise two-electron electrochemical reduction of 1 and 2 results in dissociation of CO and PPh(3), respectively, and formation of the [Os(3)(CO)(9)(tmbp)](2-) ion. The initially produced radical anions of the parent clusters, in which the odd electron is predominantly localized on the tmbp ligand, are sufficiently stable at low temperatures and can be observed with IR spectroelectrochemistry. The electron-deficiency of the cluster core in 1 permits facile electrocatalytic substitution of a CO ligand by tertiary phosphane and phosphite donors.     

Bis[(2-diphenylphosphino)phenyl]mercury: a P-donor ligand and precursor to mixed metal-mercury (d(8)-d(10)) cyclometalated complexes containing 2-C(6)H(4)PPh(2)

Treatment of HgCl(2) with 2-LiC(6)H(4)PPh(2) gives [Hg(2-C(6)H(4)PPh(2))(2)] (1), whose phosphorus atoms take up oxygen, sulfur, and borane to give the compounds [Hg[2-C(6)H(4)P(X)Ph(2)](2)] [ X = O (3), S (4), and BH(3) (5)], respectively. Compound 1 functions as a bidentate ligand of wide, variable bite angle that can span either cis or trans coordination sites in a planar complex. Representative complexes include [HgX(2) x 1] [X = Cl (6a), Br (6b)], cis-[PtX(2) x 1] [X = Cl (cis-7), Me (9), Ph (10)], and trans-[MX(2) x 1] [X = Cl, M = Pt (trans-7), Pd (8), Ni (11); X = NCS, M = Ni (13)] in which the central metal ions are in either tetrahedral (6a,b) or planar (7-11, 13) coordination. The trans disposition of 1 in complexes trans-7, 8, and 11 imposes close metal-mercury contacts [2.8339(7), 2.8797(8), and 2.756(8) A, respectively] that are suggestive of a donor-acceptor interaction, M --> Hg. Prolonged heating of 1 with [PtCl(2)(cod)] gives the binuclear cyclometalated complex [(eta(2)-2-C(6)H(4)PPh(2))Pt(mu-2-C(6)H(4)PPh(2))(2)HgCl] (14) from which the salt [(eta(2)-2-C(6)H(4)PPh(2))Pt(mu-2-C(6)H(4)PPh(2))(2)Hg]PF(6) (15) is derived by treatment with AgPF(6). In 14 and 15, the mu-C(6)H(4)PPh(2) groups adopt a head-to-tail arrangement, and the Pt-Hg separation in 14, 3.1335(5) A, is in the range expected for a weak metallophilic interaction. A similar arrangement of bridging groups is found in [Cl((n)Bu(3)P)Pd(mu-C(6)H(4)PPh(2))(2)HgCl] (16), which is formed by heating 1 with [PdCl(2)(P(n)()Bu(3))(2)]. Reaction of 1 with [Pd(dba)(2)] [dba = dibenzylideneacetone] at room temperature gives [Pd(1)(2)] (19) which, in air, forms a trigonal planar palladium(0) complex 20 containing bidentate 1 and the monodentate phosphine-phosphine oxide ligand [Hg(2-C(6)H(4)PPh(2))[2-C(6)H(4)P(O)Ph(2)]]. On heating, 19 eliminates Pd and Hg, and the C-C coupled product 2-Ph(2)PC(6)H(4)C(6)H(4)PPh(2)-2 (18) is formed by reductive elimination. In contrast, 1 reacts with platinum(0) complexes to give a bis(aryl)platinum(II) species formulated as [Pt(eta(1)-C-2-C(6)H(4)PPh(2))(eta(2)-2-C(6)H(4)PPh(2))(eta(1)-P-1)]. Crystal data are as follows. Compound 3: monoclinic, P2(1)/n, with a = 11.331(3) A, b = 9.381(2) A, c = 14.516 A, beta = 98.30(2) degrees, and Z = 2. Compound 6b x 2CH(2)Cl(2): triclinic, P macro 1, with a = 12.720(3) A, b = 13.154(3) A, c = 12.724(2) A, alpha = 92.01(2) degrees, beta = 109.19(2) degrees, gamma = 90.82(2) degrees, and Z = 2. Compound trans-7 x 2CH(2)Cl(2): orthorhombic, Pbca, with a = 19.805(3) A, b = 8.532(4) A, c = 23.076(2) A, and Z = 4. Compound 11 x 2CH(2)Cl(2): orthorhombic, Pbca, with a = 19.455(3) A, b = 8.496(5) A, c = 22.858(3) A, and Z = 4. Compound 14: monoclinic, P2(1)/c, with a = 13.150(3) A, b = 12.912(6) A, c = 26.724(2) A, beta = 94.09(1) degrees, and Z = 4. Compound 20 x C(6)H(5)CH(3).0.5CH(2)Cl(2): triclinic, P macro 1, with a = 13.199(1) A, b = 15.273(2) A, c = 17.850(1) A, alpha = 93.830(7), beta = 93.664(6), gamma = 104.378(7) degrees, and Z = 2.     

2‐Chloro‐4,5‐dihydroimidazole,Part X. Revisiting route to N‐heteroarylimidazolidin‐2‐ones

The ureidation reactions of 2‐ and 4‐picoline N‐oxides with 2‐chloro‐4,5‐dihydroimidazole are described. A mechanism of novel thioureidation reaction of 4‐picoline N‐oxide with 2‐(4,5‐dihydro‐1H‐imidazol‐2‐ylthioxy)‐4,5‐dihydro‐1H‐imidazole is proposed. Structural assignment is confirmed by ¹H and ¹³C nmr as well as by X‐ray crystallography.     

Synthesis and properties of new soluble aromatic polyamides and polyimides on the basis of N,N′‐bis(3‐aminobenzoyl)‐N,N′‐diphenyl‐1,4‐phenylenediamine

A new N‐phenylated amide (N‐phenylamide) unit containing aromatic diamine, N,N′‐bis(3‐aminobenzoyl)‐N,N′‐diphenyl‐1,4‐phenylenediamine, was prepared by the condensation of N,N′‐diphenyl‐1,4‐phenylenediamine with 3‐nitrobenzoyl chloride, followed by catalytic reduction. Two series of organosoluble aromatic poly(N‐phenylamide‐imide)s and poly(N‐phenylamide‐amide)s with inherent viscosities of 0.58–0.82 and 0.56–1.21 dL/g were prepared by a conventional two‐stage method and the direct phosphorylation polycondensation, respectively, from the diamine with various aromatic dianhydrides and aromatic dicarboxylic acids. All polyimides and polyamides are amorphous and readily soluble in many organic solvents such as N,N‐dimethylacetamide and N‐methyl‐2‐pyrrolidone. These polymers could be solution cast into transparent, tough, and flexible films with high tensile strengths. These polyimides and polyamides had glass‐transition temperatures in the ranges of 230–258 and 196–229 °C, respectively. Decomposition temperatures of the polyimides for 10% weight loss all occurred above 500 °C in both nitrogen and air atmospheres. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2564–2574, 2002     

Diaquabis(1,3‐propanediamine‐κ2N,N′)nickel(II) bis(sulfanilate)

The title compound, [Ni(C₃H₁₀N₂)₂(H₂O)₂](C₆H₆NO₃S)₂, contains alternating layers of sulfanilate anions and di­aqua­bis(1,3‐propane­di­amine)­nickel(II) cations. The Ni atom lies on an inversion centre and is hexacoordinated by the 1,3‐propane­di­amine ligands, which function as N,N′‐bidentate ligands, and the water mol­ecules, which are in a trans arrangement. The sulfanilate anions are arranged in layers, with the sulfonate and amine groups directed towards opposite sides of the layer. The structure is stabilized by a network of hydrogen bonding between the O and N atoms of the sulfanilate anions, the water mol­ecules, and the N atoms of the 1,3‐propane­di­amine ligands.     

New [g]-fused [1,2,4]triazolo[1,5-c]pyrimidines: Synthesis of pyrido[3,2-e] and [4,3-e][1,2,4]triazolo[1,5-c]pyrimidine,pyrimido[5,4-e][1,2,4]triazolo[1,5-c]pyrimidine and [1,2,4]triazolo[1,5-c]pteridine derivatives

A number of 2-aryl-substituted pyrido[3,2-e] and [4,3-e][1,2,4]triazolo[1,5-c]pyrimidines and [1,2,4]triazolo[1,5-c]pteridines 11,12a,b,e , their corresponding 5-carbonyl derivatives 7,8a,b,e and some pyrimido[5,4-e][1,2,4]triazolo[1,5-c]pyrimidin-5-ones 7,8c,d have been synthesized, according to different pathways. The new tricyclic heterocycles were prepared with the aim of studying their possible benzodiazepine receptors affinity.     

Heterocyclen aus α-nitroolefinen. XI . 1,2-oxazine aus α-nitroolefinen und β-dicarbonylverbindungen

Dihydro-1,2-oxazines 8 and 12-oxazines 12 are formed by the reaction of the nitronic acids of the adducts of α-nitroolefins and β-dicarbonyl compounds ( 6 ) by two ways: A ) The nitronic acids 6 are heated in a boiling solution of urea in ethanol or methanol. B ) The nitronic acids 6 are reduced with an aqueous solution of ammoniachloride and sodium sulfide. ¹H-nmr and ¹³C-nmr investigations prove the constitutions. The mechanism is discussed.