Polyarylaminophosphazene copolymers

A series of polyarylaminophosphazene copolymers have been prepared and are described. In each preparation, two arylamines were allowed to competitively react with polydichlorophosphazene, and the substituent ratios of the resulting copolymers, determined by high-temperature ¹H-NMR spectroscopy, generally reflect expected steric and electronic effects on the relative reactivities of the arylamines studied. The copolymers have intrinsic viscosities of 0.64–1.25 dl/g, glass transition temperatures of 75–104°C, and decomposition temperatures of 220–260°C. These properties, which are comparable to those of polyarylaminophosphazene homopolymers, are discussed in regard to what they may reflect about the structure of the polymers.     

Reactions of DI-η5-cyclopentadienyltricarbonyltriphenylphosphinediiron; an improved synthesis of the cyclopentadienylcarbonyliron tetramer

The compound (C₅H₅)₂Fe₂(CO)₃PPh₃, previously obtained by the photolysis of (C₅H₅)₂Fe₂(CO)₄ with PPh₃, may also be obtained by reflluxing these same reactants in benzene. The compound was isolated in pure form by means of low temperature column chromatography. It is unstable in solution in the absence of added PPh₃. Solid samples also are unstable over long periods of time. Decomposition in solution is complete within one hour at 80° yielding a mixture of (C₅H₅)₂Fe₂(CO)₄ and (C₅H₅)₄Fe₄(CO)₄. This reaction is suppressed by excess PPh₃. Heating a mixture of (C₅H₅)₂Fe₂(CO)₃PPh₃ and P(OEt)₃ gives a nearly quantitative yield of (C₅H₅)₂Fe₂(CO)₃P(OEt)₃. Refluxing a xylene solution of (C₅H₅)₂Fe₂(CO)₄ containing a slight molarr excess of PPh₃ for 7 h results in the isolation of (C₅H₅)₄Fe₄(CO)₄ in 56% yield, making this reaction by far the most convenient method for the preparation, in gram quantities, of this transition metal cluster.     

Lewis-Base Adducts of Group 11 Metal(I) Compounds. LXXVI Structural Studies in the Copper(I) Halide : Norbornadiene System

The structural characterizations of some copper(I) halide (CuX) adducts with norbornadiene (nbd) are recorded. CuCl : nbd (1:1)₄ (a redetermination), (2:1)_2(|), are systems both based around Cu₄Cl₄ cubane-type cluster arrays. CuBr : nbd (7:3)_(|)( 0.5 MeOH), a complex polymer with 3-symmetry, is believed to be the complex previously described as an adduct of 2:1 stoichiometry. Attempts to obtain an iodide counterpart have resulted in the definition of an ephemeral adduct CuI : MeCN (3:2)_(|). 0.5 C₇H₈ in which, remarkably, the nbd is uncoordinated; the complex is a polymer, related to the [AgX(quinoline)]_(|) (X = Cl, Br) saddle polymer.     

Gyromagnetic ratios of low-lying rotational states in156, 158, 160Gd

Transient-field precessions were measured simultaneously for levels in the ground-state bands of^{156, 158, 160}Gd as ions of these nuclei traversed a thin polarized Fe foil. Relative g-factors of levels up to 6 ₁ ⁺ were deduced, those of the 4 ₁ ⁺ levels being determined with greatest precision. In contrast with the conclusions of the recent report by Alzner et al. [1], our results are consistent with g(4 ₁ ⁺ ) having the same value in all three isotopes and imply g(2 ₁ ⁺ )=g(4 ₁ ⁺ ) in¹⁵⁶Gd, consistent with nuclear structure models.