Thermal Deamination-anation in Cobalt(III) Thiocyanate Complexes. Novel decarbonylation of the equatorial amide ligand

The solid state thermal behavior of trans-[Co(bpb)(amine)2]NCS⋅H2O complexes where (bpb)=[N,N'-bis(2-pyridinecarboxamido-N)-1,2-benzene], and amine=pyrrolidine (prldn)(1), and benzylamine (bzlan) (2), and trans-[Co(bpb)(piperidine)2]ClO4⋅H2O (3) (mixed with KSCN), has been studied using thermoanalytical techniques, infrared spectroscopy, and pyrolysis coupled to both infrared and mass spectrometry, PY/FTIR and PY/MS. The deamination-anation reaction is clearly observed for all three complexes. The estimated values of E a for the deamination-anation are: E a(1)=246.8 kJ mol−1, E a(2)=255.7 kJ mol−1, E a(3)=234.7 kJmol−1. The trend in E a values is rationalized based on the ligand field strength of the amines and the structural effects. A novel decarbonylation of the amide CO group from the equatorial ligand is observed after the release of one amine molecule. This process has been monitored for complex (1) by FTIR in the carbonyl region and by mass spectrometry for the detection of CO2 at 280°C. The activation energy of this process is estimated for complex (1) (662.5 kJ mol−1). The reaction scheme for the observed reactions is propose

Intrachain antiferromagnetic exchange in a 1D branched-chain built of two different copper(II) centres interlinked by end-on azido and phenoxo bridges: electron density map, electrochemical and magnetic properties

A 1D, end-on azido- and phenoxo-bridged, coordination polymer, [Cu-2(mu-NAPPR)(mu(1,1)-N-3)(2)](n) (1), (NAPPR(2-) = 1,3-bis(naphthylideneimino) propane dianion), was synthesized and characterized. The 1D branched-chain is built of two types of slightly different, square-pyramidal, Cu(II) ions with different sets of donor atoms. Temperature-and field-dependent magnetic analyses reveal an antiferromagnetic interaction between copper centres in the main chain (Cu-2) mediated by EO-azide bridges along the chain. The interaction between the copper centres Cu1 (in the branches of the main chain) and Cu-2 is very weak and is included by means of an own Weiss constant theta'. The electron density map of 1 from synchrotron data shows that the d(x2-y2) orbitals of Cu-2 are not well described by the procrystal model, a difference which might be meaningful for the magnetic properties. Cyclic voltammetry studies show two different redox waves with a large difference between the redox potentials of the two types of copper centres (1.21 V). The resulting data are consistent with the crystal structure of this complex determined by single crystal X-ray diffraction

Inhibitive effect of sodium (E)-4-(4-nitrobenzylidenamino) benzoate on the corrosion of some metals in sodium chloride solution

The inhibition performance of a novel anionic carboxylic Schiff base, sodium (E)-4-(4-nitrobenzylideneamino)benzoate (SNBB), was investigated for various metals, namely low carbon steel F111, pure iron and copper, in neutral 10 mM NaCl solution. Potentiodynamic polarization, scanning vibrating electrode technique (SVET), quantum chemical (QC) calculation, and molecular dynamics (MD) simulation were employed. The potentiodynamic polarization data showed that SNBB acts as an effective corrosion inhibitor for both iron and F111 steel, but it is not effective for the copper. In situ spatially-resolved SVET maps evidenced a major change in surface reactivity for Fe and F111 steel immersed in 10 mM aqueous solution in the absence and in the presence of SNBB. Featureless ionic current density distributions were recorded in the presence of SNBB at both their spontaneous open circuit potential (OCP) and under mild anodic polarization conditions, while major ionic flows were monitored above the metals in the absence of SNBB. On the basis of computer simulations, it is proposed that SNBB produces a stable chelate film on iron and steel surfaces that accounts for the good corrosion inhibition efficiency observed. The different inhibition efficiencies of SNBB molecules on the iron and copper was attributed to the special chemical structure of SNBB molecule and its different chelation ability with the released metal ions on the metal surface. The QC calculations also confirmed the high corrosion inhibition efficiency of SNBB. The MD simulation indicated higher binding energy of SNBB on iron surface compared to that of copper surface. The interaction mode of SNBB on iron and F111 steel surfaces corresponds to a mixed chemical and physical adsorption, and it obeys the Langmuir isother

Solid state kinetic parameters and mechanism for deamination-anation of trans-[Co(III)(acacen)(amine)2]NCS

NRC publication: Ye