Cobalt-Assisted Condensation of 2-Butanone Oxime and Acetone: Synthesis and X-ray Structure of the Novel Acetaldiimine Complex [CoI2{((CH3CH2)(CH3)C=NO)2C(CH3)2}]

Oxazolidine Nitroxide Transformation in a Coordination Sphere of the Ln3+ Ions

Upon the interaction of the hydrated lanthanide(III) salts found in acetonitrile solution with a tripodal paramagnetic compound, 4,4-dimethyl-2,2-bis(pyridin-2-yl)-1,3-oxazolidine-3-oxyl (Rad), functionalized by two pyridyl groups, three neutral, structurally characterized complexes with diamagnetic polydentate ligands—[Dy(RadH)(hbpm)Cl₂], [Yb₂(ipapm)₂(NO₃)₄], and [Ce₂(ipapm)₂(NO₃)₄(EtOAc)₂]—were obtained. These coordination compounds are minor uncolored crystalline products, which were formed in a reaction mixture due to the Rad transformation in a lanthanide coordination sphere, wherein the processes of its simultaneous disproportionation, hydrolysis, and condensation proceed differently than in the absence of Ln ions. The latter fact was confirmed by the formation of the structurally characterized product of the oxazolidine nitroxide transformation during its crystallization in toluene solution. Such a conversion in the presence of 4f elements ions is unique since no similar phenomenon was observed during the synthesis of the 3d-metal complexes with Rad.

Synthesis, characterization and properties of tetra((1-hydroxyimino-methylnaphthalen-2-yloxy)methyl)ethene and its homo-dinuclear metal complexes: a combined experimental and theoretical investigation

Tetra((1-hydroxyiminomethylnaphthalen-2-yloxy)methyl)ethene (THIMNYOME), H(4)L, was synthesized by the agents of 2-hydroxy-1-naphtaldehyde, tetra(bromomethyl)ethene and hydroxylamine hydrochloride in two steps. Characterization of THIMNYOME and its dinuclear complexes was made by elemental analyses, IR, (1)H- and (13)C NMR, UV-vis, electrospray ionisation mass spectra, molar conductivities and magnetic susceptibility measurements. In the light of these results, it was suggested that the ligand coordinate to each metal atom by the two ether oxygen, two nitrogen atoms of oxime imine (CN) and an axial oxygen of perchlorate to form pseudo square-pyramidal complexes with Ni(II), Cu(II) and Zn(II). Molar conductivity measurements reveal that all the complexes are non-electrolytes. In addition, the full geometric optimization of the tetraoxime ligand (4) has been made by the B3LYP/6-31G(d) level in order to establish a stable conformation. Additionally, all the complex structures have been studied in the B3LYP/LANL2DZ level. NBO charge distribution and the characteristics of frontier molecular orbitals of these complexes have also been investigated in order to see the electrons movement between ligand and metal atom in the same level.

Oxazoles XXII. The Cobalt(II) Coordination Chemistry of 2-(ortho-Anilinyl)-4,4-dimethyl-2-oxazoline: Syntheses, Properties, and Solid-State Structural Characterization

Ethanol solutions of the cobalt(ii) halides react with an excess of 2-(ortho-anilinyl)-4,4-dimethyl-2-oxazoline (1: i.e. 2-(2′-anilinyl)-4,4-dimethyl-4,5-dihydro-1,3-oxazole) to give isolable κ2-N,N′-bonded species of 1 in good to excellent yields. The complexes CoX2(1-κ2-N,N′)·(H2O) n have been isolated for X = Cl (2: n = 1/2), X = Br and I (3 and 4, respectively; n = 0); the solid-state structures (X-ray) are in accordance with those suggested by UV-visible spectroscopy and conductivity measurements (i.e. non-ionic complexes with a pseudo-tetrahedral coordination motif around Co). In contrast, reaction of excess 1 with Co(NCS)2 forms the octahedral (UV-visible, X-ray) bis-isothiocyanato complex Co(NCS-κ1-N′)2(1-κ2-N,N′)2 (5) with cis-oriented NCS groups and trans-disposed oxazolines. Calculations at the PM3(tm) level of theory suggest that this isomer is close in energy to the four other possible (gas-phase) isomers. Treatment of ethanol solutions of hydrated cobaltous nitrate with excess 1 yields a material analyzed as [Co(NO3)(1)(H2O)2](NO3) (6a) and a small amount (less than 1%) of a second complex (6b); the latter has been characterized (X-ray) as the hydrated octahedral complex [Co(NO3-κ1-O)(1-κ2-N,N′)2(OH2)](NO3). In this case, the nitrato and aqua groupings are located cis to one another and trans to the coordinated –NH2 groups. Complex 6a is surmised to have a [Co(NO3-κ2-O,O′)2(1-κ2-N,N′)(OH2)2]NO3 structure. Cobalt compounds 2–5 and 1 have also been screened for their antifungal properties against Aspergillus niger, Aspergillus flavus, Candida albicans, and Saccharomyces cerevisiae but were found to be inactive in this regard.