Mixed Allyl Research Articles

Frontispiece: Mixed Allyl Rare‐Earth Borohydride Complexes: Synthesis, Structure, and Application in (Co‐)Polymerization Catalysis of Cyclic Esters

Such rare-earth (RE) complexes (RE=La, Nd, Sm, Y, Sc) contain allyl and borohydride groups that are both potential initiators towards the ring-opening polymerization of cyclic esters. They display high activity towards homo- and co-polymerization of l-LA and ϵ-CL, producing a wide range of copolymers. The borohydride moiety is shown to preferentially initiate the polymerization. For more information see the Full Paper by F. Bonnet, M. Visseaux et al. on page 15644 ff.

Mixed Allyl Rare-Earth Borohydride Complexes: Synthesis, Structure, and Application in (Co-)Polymerization Catalysis of Cyclic Esters.

A series of new trivalent rare-earth allyl-borohydride complexes with the formula [RE(BH4 )2 (C3 H5 )(thf)x ] (RE=Sc (1), x=2; RE=Y (2) and La (3), x=3) were synthesized by reaction of the corresponding rare-earth trisborohydrides [RE(BH4 )3 (thf)x ] with half an equivalent of bis(allyl)magnesium. The complexes were fully characterized by determining their X-ray structure. Similar to their previously described Nd (4) and Sm (5) analogues, these complexes display a monomeric structure with two terminal trihapto BH4 groups, one π-η3 allyl ligand, three THF molecules for complexes 2 and 3, and two THF molecules for complex 1. The catalytic behavior of complexes 1-5 toward the ring-opening polymerization (ROP) of l-lactide (l-LA) and ϵ-caprolactone (ϵ-CL) was assessed. The Nd complex featured the best activity toward l-LA (turnover frequency (TOF)=1300 h-1 ) and the order was Nd>La>Sm>Y>Sc. Complexes 1-3 were found very active for the ROP of ϵ-CL (TOF=166 000 h-1 ), which is in line with the already established exceptionnally high performance of complexes 4 and 5. With both monomers, it was shown that the borohydride moiety was the preferentially initiating group, rather than the allyl one. The random copolymerization of l-LA and ϵ-CL was performed with complexes 1-5, in the absence or in the presence of benzyl alcohol as a chain-transfer agent, affording copolymers with ϵ-caprolactone up to 62 % inserted. The copolymers synthesized display a variety of microstructures, that is, blocky, random, or quasi-alternating.

Mixed Allyl–Borohydride Lanthanide Complexes: Synthesis of Ln(BH4)2(C3H5)(THF)3 (Ln = Nd, Sm), Characterization, and Reactivity toward Polymerization

New mixed allyl–borohydrido lanthanide complexes Ln(BH4)2(C3H5)(THF)3 (Ln = Nd (1), Sm (2)) could be prepared in good yield by reacting Ln(BH4)3(THF)3 (Ln = Sm, Nd) with 1/2 equiv of Mg(C3H5)2(THF)x. X-ray structure analysis revealed monomeric structures with two terminal BH4 ligands, one π-allyl ligand, and three THF molecules. In an assessment of isoprene polymerization, 1 afforded trans-1,4-polyisoprene in good yield, as a single component or in combination with Mg cocatalyst. Both 1 and 2 were found to be extremely active toward e-caprolactone polymerization.

A Practical Synthesis of Mixed Allyl and Allenesulfinates

A new, general, and efficient method for the preparation of mixed sulfoxylates (ROSOR') by treatment of symmetrical dialkoxy disulfides (ROSSOR) with alcohols at room temperature has been found. Subsequent spontaneous [2,3]-sigmatropic rearrangements of mixed sulfoxylates such as alkyl allyl and alkyl propargyl sulfoxylates afford mixed alkyl allyl and alkyl allenesulfinates in good yield. The latter are not readily available by other routes.

Ether formation from allylic alcohols catalyzed by samarium trichloride

The behaviour of various allylic alcohols in the presence of catalytic amounts of SmCl 3 (by heating in 1,2-dichloroethane) has been studied. Diallyl ethers are obtained in many cases in good yields. Mixed allyl alkyl ethers are also prepared if 2–5 equivalents of an aliphatic alcohol is present. The reactions are interpreted as proceeding through a pseudo allylic carbonium intermediate initiated by a preliminary complexation of the allyl hydroxyl to the samarium ion.

Molybdenum, tungsten, and manganese carbonyl compounds incorporating novel tridentate chelating dimethyl(1-pyrazolyl)(ethanolamino)gallate ligands

The coordinating properties of the tridentate tris-chelating ligand, [Me2Ga(OCH2CH2NH2)(N2C3H3)]−, and its three methyl substituted derivatives (methyl substitution on the amino nitrogen and the 3,5 positions of the pyrazolyl ring) have been studied in a series of molybdenum, tungsten, and manganese carbonyl compounds. Mixed allyl carbonyl and nitrosyl carbonyl compounds of both molybdenum and tungsten have been characterized, and a series of tricarbonyl manganese compounds studied. All the complexes are monomeric octahedral species having the tris-chelating ligands in fac coordination. Steric factors influence the arrangement of the three remaining groups in the mixed octahedral complexes (i.e. allyl carbonyl and nitrosyl carbonyl derivatives) and particular site preferences are inferred from spectroscopic measurements.

The optical-mechanical properties of polymers based on mixed allyl esters of dicarboxylic acids at low temperatures

The optical-mechanical properties of polymers based on mixed allyl esters of dicarboxylic acids have been investigated in relation to their chemical structure in the temperature range 150–300°K. Possible versions of segmental mobility in the glass-like state are considered, and the size of contributions on the part of the elastic and Gough deformation components have been estimated.

Optical and mechanical properties of polymers based on bis-(p-carballyloxyphenyl) esters of aliphatic and aromatic dibasic acids

A study was made of the heat stability and optical and mechanical properties of polymers based on mixed allyl esters of dicarboxylic acids in relation to chemical structure. Possible damage to three dimensional network and the effect of defects on deformation and optical sensitivity of polymers was examined.

Formation of mixed allyl esters during reaction of higher olefins with palladium chloride in anhydrous carboxylic acid solutions

Formation of mixed allyl esters during reaction of higher olefins with palladium chloride in anhydrous carboxylic acid solutions