Synthesis and Characterization of N-Substituted Polyether-Block-Amide Copolymers.

A series of N-substituted polyether-block-amide (PEBA-X%) copolymers were prepared by melt polycondensation of nylon-6 prepolymer and polytetramethylene ether glycol at an elevated temperature using titanium isopropoxide as a catalyst. The structure, thermal properties, and crystallinity of PEBA-X% were investigated using nuclear magnetic resonance spectroscopy, Fourier-transform infrared spectroscopy, differential scanning calorimetry, wide angle X-ray diffraction, and thermogravimetric analysis. In general, the crystallinity, melting point, and thermal degradation temperature of PEBA-X% decreased as the incorporation of N-methyl functionalized groups increased, owing to the disruption caused to the structural regularity of the copolymer. However, in N-acetyl functionalized analogues, the crystallinity first dropped and then increased because of a new γ form arrangement that developed in the microstructure. After the cross-linking reaction of the N-methyl-substituted derivative, which has electron-donating characteristics, with poly(4,4'-methylenebis(phenyl isocyanate), the decomposition temperature of the resulting polymer significantly increased, whereas no such improvements could be observed in the case of the electro-withdrawing N-acetyl-substituted derivative, because of the incompleteness of its cross-linking reaction.

Synthesis and catalytic application of magnesium complexes bearing pendant indolyl ligands.

Three novel indole-based ligand precursors [HIndPh(R), R = methoxy, HIndPh(OMe) (); thiomethoxy, HIndPh(SMe) (); and N,N'-dimethylamino, HIndPh(NMe2) ()] have been synthesized via Sonogashira and cyclization reactions with moderate to high yield. Reactions of these ligand precursors with 0.6 equivalent of Mg(n)Bu2 in THF afforded the magnesium bis-indolyl complexes , respectively. All the ligand precursors and related magnesium complexes have been characterized by NMR spectroscopy and elemental analyses. The molecular structures are reported for compounds and . Under optimized conditions, compound demonstrates efficient catalytic activities towards the ring opening polymerization of l-lactide and ε-caprolactone in the presence of BnOH.

Palladacycles bearing tridentate CNS-type benzamidinate ligands as catalysts for cross-coupling reactions.

Three pendant benzamidines, [Ph-C(=NC(6)H(5))-{NH(E)}] [E = -(CH(2))(2)SMe (1); -(CH(2))(2)S(t)Bu (2); -o-C(6)H(4)SMe (3)], are described. Reactions of 1, 2 or 3 with one molar equivalent of Pd(OAc)(2) in CH(2)Cl(2) give the palladacyclic complexes, [Ph-C{-NH(η(1)-C(6)H(4))}{=N(E)}]Pd(OAc) [E = -(CH(2))(2)SMe (4); -(CH(2))(2)S(t)Bu (5); -o-C(6)H(4)SMe (6)], as mononuclear palladium complexes respectively. A minor product described as 5', {[Ph-C{-N(C(6)H(5))}{-N(CH(2))(2)S(t)Bu}]Pd(OAc)}(2), was isolated as benzamidinate-bridged dinuclear palladium complex upon recrystallizing from Et(2)O/hexane solution. Treatment of 1, 2 or 3 with one molar equivalent of PdCl(2) in the presence of NEt(3) in CH(2)Cl(2) gives the palladacyclic complexes, [Ph-C{-NH(η(1)-C(6)H(4))}{=N(E)}]PdCl [E = -(CH(2))(2)SMe (7); -(CH(2))(2)S(t)Bu (8); -o-C(6)H(4)SMe (9)], as mononuclear palladium complexes respectively. The crystal and molecular structures are reported for compounds 5, 5' and 6-8. The application of these palladacyclic complexes to the Suzuki and Heck coupling reactions was examined.

Synthesis and catalytic application of aluminium anilido-pyrazolate complexes.

A series of aluminium complexes containing anilido-pyrazolate ligands is described. Reactions of four anilido-pyrazolate ligand precursors, HNPhPz, HNPhTriMePz, HNPhOMePz, or HNPhSMePz [HNPhPz = ortho-C6H4(NH-phenyl)(1-pyrazole); HNPhTriMePz = ortho-C6H4(NH-2,4,6-trimethylphenyl)(1-pyrazole); HNPhOMePz = ortho-C6H4(NH-2-methoxyphenyl)(1-pyrazole); HNPhSMePz = ortho-C6H4(NH-2-methylthiophenyl)(1-pyrazole)], with one molar equivalent of AlMe3 in toluene give the aluminium dimethyl complexes, (NArPz)AlMe2 [Ar = phenyl, (NPhPz)AlMe2 (1); Ar = 2,4,6-trimethylphenyl, (NPhTriMePz)AlMe2 (2); Ar = 2-methoxyphenyl, (NPhOMePz)AlMe2 (3); Ar = 2-methylthiophenyl, (NPhSMePz)AlMe2 (4)], respectively. The molecular structures are reported for compounds 1 and 3. Their catalytic activities toward the ring opening polymerisation reaction of -caprolactone in the presence of BnOH are also under investigation.

Magnesium complexes containing bis-amido-oxazolinate ligands as efficient catalysts for ring opening polymerisation of L-lactide.

A series of magnesium bis(amido-oxazolinate) complexes have been described. Reactions of six amido-oxazolinate ligand precursors, HNC(2)(Me)Oxa, HNC(2)(OMe)Oxa, HNC(2)(StBu)Oxa, HNPhOxa, HNPh(OMe)Oxa or HNPh(SMe)Oxa, with half molar equivalent of Mg(n)Bu(2) in hexane yield the magnesium bis(amido-oxazolinate) complexes, (NC(2)(E)Oxa)(2)Mg [C(2)(E) = propyl, (NC(2)(Me)Oxa)(2)Mg (1); C(2)(E) = 2-methoxyethyl, (NC(2)(OMe)Oxa)(2)Mg (2); C(2)(E) = 2-tert-butylthioethyl, (NC(2)(StBu)Oxa)(2)Mg (3)], or magnesium bis(anilido-oxazolinate) complexes, (NArOxa)(2)Mg [Ar = phenyl, (NPhOxa)(2)Mg (4); Ar = 2-methoxyphenyl, (NPh(OMe)Oxa)(2)Mg (5); Ar = 2-methylthiophenyl, (NPh(SMe)Oxa)(2)Mg (6)], respectively. The molecular structures are reported for compounds 1, 2, 5 and 6. Their catalytic activities toward the ring opening polymerisation of L-lactide in the presence of benzyl alcohol are also under investigation.

Zinc anilido-oxazolinate complexes as initiators for ring opening polymerization.

Three new anilido-oxazolines, ortho-C(6)H(4)(NHAr')(4,4-dimethyl-2-oxazoline) [Ar'=2,4,6-trimethylphenyl, HNPh(TriMe)Oxa (1); 2,6-diisopropylphenyl, HNPh(DiiPr)Oxa (2); 2-methoxyphenyl, HNPh(OMe)Oxa (3)], have been prepared. Reactions of 1 or 2 with one molar equivalent of ZnEt(2) in tetrahydrofuran or hexane solution give the zinc ethyl complexes (NPh(TriMe)Oxa)ZnEt (4) and (NPh(DiiPr)Oxa)ZnEt (5). The dinuclear zinc benzyloxide complexes, [(NAr'Oxa)Zn(mu-OBn)](2), [Ar'=2,4,6-trimethylphenyl, (6); 2-methoxyphenyl, (7)], were synthesized by the reaction of 4 with one molar equivalent of benzyl alcohol in tetrahydrofuran solution (for 6) or by treatment of with 3 one molar equivalent of ZnEt(2) in tetrahydrofuran solution followed by the addition of one molar equivalent of benzyl alcohol (for 7). The molecular structures are reported for compounds 6 and 7. Their catalytic activities toward the ring opening polymerization reactions are under investigation.