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depend strongly on solution conditions, there is little reason to expect much similarity between UOzz+-ATP complexes and monatomic cation-ATP complexes in which all three phosphate groups are involved, since ligands attached to the uranyl ion are restricted to positions close to its equatorial plane. On the other hand, one might look for relationships between UOzz+-ATP chelates and those monatomic cation-ATP complexes, like Cu2+-ATP, in which only two phosphate groups are involved, but it is apparent that much more extensive and systematic studies, e.g., over wider pH and concentration ranges, are needed for systems containing monatomic cations than are now available. It is of interest to this point that BrintzingerZ9 in 1961 claimed that his pH titrations showed involvement of the ribose hydroxyl group in the complexation of Mn2+, Co2+, Ni2+, Znz+, and Cu2+ by ATP in basic solution. However, he believed that, unlike the binding in our suggested UOz2+-ATP structures, there was an intervening water molecule attached by its oxygen atom to the metal and by hydrogen bridges to the two ribose hydroxyl oxygens.(29) H. Brintzinger, Helu. Chim. Acta, 44, 1199 (1961). and Ni2+ interact simultaneously with all three phosphateThe latter two ions were studied only at p H 8.5-9. At pH -7 all four paramagnetic ions bind to the adenine ring of ATP also,2",2bb the latter three all the time they are bound to the phosphate."'To resolve apparent disagreement between these conclusions and previous ultravioletz6 and temperature-jump27 studies which involved solutions containing only M ATP, Sternlicht, et U E . ,~~ performed nmr experiments on Mnz+-ATP solutions with only = 5 X M ATP. These authors claim to have shown that at low ATP concentration, = 5 X M , primarily 1 : 1 complexes are present, but that 1 : 2 complexes predominate at high ATP concentration, =0.1 M , i.e., with only = M Mn2+ in each case. Sternlicht, et al., believe that in the 1 :2 complex the Mn2+ binds simultaneously to the phosphate of one nucleotide and to the adenine of the second nucleotide, but that the metal is bound only to the phosphate in the 1 : 1 complex.Abstract: The boron nuclear spin coupling constant of the triphenylboron anion radical is positive. The assignment of coupling constants to the ortho, meta, and para protons has been confirmed by a study of the tris(p-deu-teriopheny1)-and tris(3,5-dideuteriophenyl)boron esr spectra. The lines corresponding to mB = f 3/? are selectively broadened either by incomplete averaging of the anisotropic hyperfine coupling or by an unidentified reaction that modulates the boron coupling constant. Prolonged reaction of triphenylboron anion radical with alkali metals in DME degrades it to biphenyl anion radical, both halves of which comefrom the same triphenylboron. The behavior o f tris(p-chlorophenyl)boron, tris(p-methoxyphenyl)boron, tris(p-dimethylaminophenyl)boron, tris(p-tolyl)boron, several trialkylborons, diphenylboron chloride, and dimesitylboron fluoride with alkali metals is also described.ost triarylbor...

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The preparation and compatibilizing ability of heteroarm star-shaped block copolymers (6 and 8) composed of polystyrene and nylon 6 units diverged from the phosphazene core were investigated. The heteroarm star-shaped copolymers were prepared by a partial coupling reaction of the acid chloride of hexakis(4-carboxyphenoxy)cyclotriphosphazene [4, (4-ClCOC6H4O)6N3P3] with polystyrene having a terminal amino group (PSt−NH2) or poly(styryllithium), followed by the ring-opening polymerization of ε-caprolactam (ε-CL) with the residual carboxyl group in the phosphazene core. The coupling reaction of telechelic PSt−NH2 and poly(styryllthium) with 4 occurs smoothly to give carboxyphenoxycyclotriphosphazenes carrying 2.2−4.7 polystyrene chains, 5 and 7, respectively. The polymerization of ε-CL with hexakis(4-carboxyphenoxy)cyclotriphosphazene [2, (4-HOOCC6H4O)6N3P3] showed that all carboxyl groups participate in the initiation of polymerization to give hexaarmed star-shaped polymers. This implies that the residual carboxyl groups in 5 and 7 could also initiate the polymerization of ε-CL. The molecular weights of copolymers obtained from the polymerization of ε-CL with 5 and 7 are in agreement with those of calculated values, suggesting the formation of heteroarm star-shaped block copolymers with phosphazene core (6 and 8). When these copolymers were used as a compatibilizer of an immiscible blend, poly(2,6-dimethylphenylene oxide) (PPO) and nylon 6, DSC profiles showed a single transition temperature that shifted to lower temperature from the T g of PPO. The SEM photograph indicates that PPO disperses regularly and finely with 0.3 μm size in the nylon domain. Furthermore, the tensile strength and elongation at break of ternary blends increased with increasing the copolymer content. These results indicate that the effective penetration of each block sequence of the heteroarm star-shaped copolymers into the blend components is operative, that is, these copolymers act as an excellent compatibilizer for PPO/nylon 6 blends.

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