Template Synthesis of a Tetraaza Macrocycle Which Involves Benzaldehyde Rather Than Formaldehyde as a Building Block. Isolation and Structure Determination of the Open-Chain Schiff Base Intermediate Complex

The classical formaldehyde building block has been replaced by the bulkier benzaldehyde in the Cu(II) template synthesis of the cyclam-like tetraaza macrocycle of type 1, in which nitroethane operated as locking fragment. The synthetic pathway involves three distinct steps: (i) Schiff base condensation of the metal-free open-chain tetramine; (ii) Cu(II) coordination and preorientation of the Schiff base; (iii) nucleophilic attack by the deprotonated nitroethane fragment and formation of the macrocyclic complex. Both the Schiff base Cu(II) complex and the Cu(II) macrocyclic complex were isolated in a crystalline form and their molecular structures were determined: {N-[2-((E)-benzylideneamino)ethyl]-N'-[2-((Z)-benzylideneamino)ethyl]propane-1,3-diamine}copper(II) nitrate: triclinic, space group P&onemacr;, with a = 12.296(5) ?, b = 10.787(6) ?, c = 10.547(7) ?, V = 1161(1) ?(3), and Z = 2 (R = 0.055, R(w) = 0.061); [(5R,6S,7S)-6-methyl-6-nitro-5,7-diphenyl-1,4,8,11-tetraazacyclotetradecane]copper(II) perchlorate: monoclinic, space group P2(1)/n, with a = 15.246(5) ?, b = 23240(7) ?, c = 8.540(4) ?, V = 2980(2) ?(3), and Z = 4 (R = 0.095, R(w) = 0.095). This allowed us to define mechanistic details of the macrocyclization process. It is suggested that the same three-step pathway takes place in the much easier and faster one-pot template syntheses of cyclam-like macrocyles, which involve formaldehyde as a building block.     

Causal loop diagrams as a de-escalation technique

Escalation of commitment, the tendency of decision makers to keep on investing in losing courses of action, has been shown to be a costly decision bias that affects many areas of decision making. Even though escalation is a widely studied phenomenon, there has been comparatively little research on how to avoid this bias. The present study focuses on de-escalation of commitment and proposes that causal loop diagrams (CLDs) can help to decrease escalating commitment to a failing course of action. By means of an experiment, this study shows that using a CLD decreases escalation tendencies.     

An unusual open cubane structure in a mu(1,1)-azido- and alkoxo-bridged tetranuclear copper(II) complex, [Cu4L2(mu(1,1)-N3)2].5H2O (H3L = N,N'-(2-Hydroxylpropane-1,3-diyl)bis-salicylideneimine)

A new end-on (EO) azido-bridged tetranuclear copper(II) complex [Cu(4)L(2)(mu(1,1)-N(3))(2)].5H(2)O derived from the ligand H(3)L (N,N'-(2-hydroxylpropane-1,3-diyl)bis-salicylideneimine) has been synthesized. Its X-ray structure shows an unusual Cu(4)O(2)N(2) open cubane core in which four copper(II) atoms are connected two by two through two mu(1,1)-azido species and three by three through two alkoxo bridges. The magnetic susceptibility data is dominated by strong antiferromagnetic interactions associated with the alkoxides and weak ferromagnetic interactions arising from the azides, in agreement with magneto-structural correlations found in the literature relative to such bridges in Cu(II) complexes.     

Influence of structural disorder on low-temperature behavior of penetration depth in electron-doped high-TC thin films

The results of Hall probe magnetic measurements in the vicinity of a DyBCO tape carrying transport or magnetization currents at 77 K were used in the inverse calculation to obtain the current distribution across the tape width. Two different methods of the inverse problem calculation were used and the results compared. The transport current applied in the absence of the external magnetic field was stepwise increased and the determined current distribution was compared with that predicted by Brandt and Indenbom. The predicted convex shape of the current distribution in the central tape section was proved. Contrary to the prediction, we have observed a drop of the current at the tape edges. This result supports the conclusions of the loss measurements in YBCO tapes [O. Tsukamoto, Supercond. Sci. Technol. 18 (5) (2005) 596]. We also mapped the magnetic field in the vicinity of the tape carrying induced magnetization currents in the absence of the transport current and determined the corresponding current distribution. Superposition of the self magnetic field and a homogeneous external magnetic field (36 mT) flattens the magnetization current distribution evidently.     

Bis(2,2′-biimidazoline)bis(isothiocyanato)Metal(II) compounds. Synthesis,characterization and lattice hydrogen bonding for Metal = Mn(II) and Ni(II)

The synthesis, characterization and X-ray structures of two compounds with the general formula trans-M(biz)₂(NCS)₂ (in which biz = 2,2′-biimidazoline and M = Mn(II) for compound 1 and Ni(II) for compound 2) are reported. Both compounds crystallize in the triclinic space group P-1 with a = 8.393(5), b = 8.946(5), c = 7.659(5) Å, α = 104.440(5), β = 106.880(5), γ = 66.180(5)^∘, V = 497.7(5) ų, Z = 1 for compound 1 and a = 8.155(2), b = 8.8190(10), c = 7.480(2) Å, α = 102.259(15), β = 106.135(13), γ = 67.706(14)^∘, V = 474.7(2) ų, Z = 1 for compound 2.Both metal ions show octahedral coordination with the four nitrogen atoms of two biz ligands in the equatorial plane and the two nitrogen atoms of two isothiocyanate anions in the axial positions. The M–N≡C angles are 166.5(2) and 167.7(2) for compounds 1 and 2, respectively. These values are in the usually obtained range for trans-isothiocyanate coordinated compounds. The sulfur atom of each isothiocyanate anion acts as acceptor for the hydrogen bond with the NH group of the biz ligands. In the IR spectrum the vibrations of the thiocyanate anion are observed at 2090 and 776 cm⁻¹ for compound 1 and at 2108 and 778 cm⁻¹ for compound 2, and these values are typical for linear-bond isothiocyanate complexes of transition metals.