Substituent effect on torsional barriers in N,N′-dibenzylhydrazobenzenes.

Substituted hydrazobenzenes were prepared and their barriers to rotation measured by DNMR spectroscopy and correlated with σ^? substituent constants with a reaction constant ?₃₀₀ = ?1.09.     

The chemistry of polycyclic arene imine. VI. 1-[N,N-di-(2-propenyl)-9-phenanthreneamine-10-yl]-1a,9b-dihydrophenanthro[9,10-b]azirine an unusual allylation product of phenanthrene 9,10-imine

Phenanthrene 9,10-imine (1) was shown to react with allyl bromide and 50% aqueous sodium hydroxide under phase transfer catalysis conditions to give the title compound 3 as the only product. The starting imine 1 is assumed to undergo initially bis alkylation to form an N,N-di-(2-propenyl)phenanthrene 9,10-iminium salt (4) which, in turn, is attacked by a deprotonated phenanthrene imine anion (5). The structure of 3 has been determined by a single crystal X-ray diffraction analysis.     

Halogeno-coordinated iron corroles

The first full assignment of (1)H NMR chemical shifts for iron corroles and the first synthesis of a series of (halogeno)iron corroles reveal very large effects of the axial ligands on the corresponding spectra, which apparently reflect differences in the relative importance of metal-to-corrole and corrole-to-metal pi-donation. These findings pave the way for a thorough analysis of the electronic structures of such complexes.     

Kantorovich-Bernstein polynomials

A gap between saturation and direct-converse theorems for Kantoro-vich-Bernstein polynomials will be closed for a steady rate of convergence. The present theorems unify the above-mentioned results. Furthermore, it is shown that for steady rates our converse results are an improvement on both weak-type converse theorems and strong-weak-type converse theorems for the Kantorovich-Bernstein polynomials.Communicated by George G. Lorentz.AMS classification: 41A27, 41A36, 41A40.     

One-Pot Synthesis of Dihalo(porphyrinato)osmium(IV) Complexes. Evidence for Monohalo(carbonyl)osmium(III) Intermediates

trans-Dichloro-, trans-dibromo-, and trans-diiodoosmium(IV) tetraarylporphyrins were obtained by extremely facile synthetic routes directly from the reactions of the corresponding (carbonyl)osmium(II) complexes with CCl(4), CBr(4), and CI(4), respectively. At short reaction times, appreciable amounts of intermediates-one for each reaction-were observed by spectroscopic investigations. These intermediates were shown to be (carbonyl)(halo)(porphyrinato)osmium(III) complexes by independent preparation of an authentic (carbonyl)(bromo)(porphyrinato)osmium(III) complex, which was identical to the reaction intermediate in the reaction of CBr(4) and very similar to those of the other reactions. This provided strong evidence for the reaction mechanism, two stepwise one-electron oxidations of the metal ion. The relatively strong binding of carbon monoxide to osmium(III) is proposed to be an important factor in avoiding dimerization of the reaction intermediates.