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.

EFFECTS OF Mg2+ AND Co2+ ON CELL DIVISION AND NUCLEOLAR CYCLE DURING MITOSIS IN ROOT TIP CELLS OF ALLIUM CEPA

Effects of Mg2+ and Co2+ on cell division and the nucleolar cycle during mitosis in root tip cells of Allium cepa were studied. The concentrations used of magnesium sulphate and cobaltous nitrate were in the range of 10−7–10−1M. The results showed that both Mg and Co can, at higher concentration, have a toxic effect on cell division comprising c-mitosis and lagging chromosomes, anaphase bridges, and chromosome stickiness. Excessive Mg and Co can also induce some silver-stained particles similar to nucleoli, which are scattered around the chromosome or in the cytoplasm during metaphase and anaphase. The possible mechanism behind this phenomenon is briefly discussed.

Chemical and spectroscopic studies in metal β-diketonates. II. Nitration of metal β-diketonates

Bis(3-nitropentane-2,4-dionato)-beryllium(II), -copper(II), and - palladium(II); tris(3-nitropentane-2,4-dionato)-aluminium(III), - chromium(III), -manganese(III), -iron(III), and -cobalt(III); tetrakis(3-nitropentane-2,4-dionato)zirconium(IV); and tris (3-nitro- 1,3-diphenylpropane-1,3-dionato)-aluminium(III) and -chromium(III) have been prepared by the nitration of the respective metal chelates of acetylacetone and 1,3-diphenylpropane-1,3-dione. Ferric nitrate, cobaltous nitrate, and nickel nitrate have been used as nitrating agents for the first time. The nitro chelates have also been prepared by a direct, single-step process using metal nitrates, acetic anhydride, and the ligands. In several cases, metal replacement reactions have been observed to be taking place in conjunction with nitration under nitration reaction conditions. Infrared, ultraviolet, and visible electronic spectra have been recorded and are discussed.